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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Cell Dev. Biol.</journal-id>
<journal-title>Frontiers in Cell and Developmental Biology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Cell Dev. Biol.</abbrev-journal-title>
<issn pub-type="epub">2296-634X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="publisher-id">1191074</article-id>
<article-id pub-id-type="doi">10.3389/fcell.2023.1191074</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Cell and Developmental Biology</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Single cell and bulk transcriptome analysis identified oxidative stress response-related features of Hepatocellular Carcinoma</article-title>
<alt-title alt-title-type="left-running-head">Zhang et al.</alt-title>
<alt-title alt-title-type="right-running-head">
<ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fcell.2023.1191074">10.3389/fcell.2023.1191074</ext-link>
</alt-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Zhang</surname>
<given-names>Shuqiao</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="author-notes" rid="fn001">
<sup>&#x2020;</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1391341/overview"/>
</contrib>
<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Li</surname>
<given-names>Xinyu</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="author-notes" rid="fn001">
<sup>&#x2020;</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1511898/overview"/>
</contrib>
<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Zheng</surname>
<given-names>Yilu</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="author-notes" rid="fn001">
<sup>&#x2020;</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Liu</surname>
<given-names>Jiahui</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/906881/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Hu</surname>
<given-names>Hao</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1000605/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Zhang</surname>
<given-names>Shijun</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1224059/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Kuang</surname>
<given-names>Weihong</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1150359/overview"/>
</contrib>
</contrib-group>
<aff id="aff1">
<sup>1</sup>
<institution>First Affiliated Hospital of Guangzhou University of Chinese Medicine</institution>, <institution>Guangzhou University of Chinese Medicine</institution>, <addr-line>Guangzhou</addr-line>, <addr-line>Guangdong</addr-line>, <country>China</country>
</aff>
<aff id="aff2">
<sup>2</sup>
<institution>Department of Hematology</institution>, <institution>The Seventh Affiliated Hospital</institution>, <institution>Sun Yat-sen University</institution>, <addr-line>Guangzhou</addr-line>, <addr-line>Guangdong</addr-line>, <country>China</country>
</aff>
<aff id="aff3">
<sup>3</sup>
<institution>Department of Traditional Chinese Medicine</institution>, <institution>The First Affiliated Hospital</institution>, <institution>Sun Yat-sen University</institution>, <addr-line>Guangzhou</addr-line>, <addr-line>Guangdong</addr-line>, <country>China</country>
</aff>
<aff id="aff4">
<sup>4</sup>
<institution>Guangdong Key Laboratory for Research and Development of Natural Drugs</institution>, <institution>Dongguan Key Laboratory of Chronic Inflammatory Diseases</institution>, <institution>School of Pharmacy</institution>, <institution>The First Dongguan Affiliated Hospital of Guangdong Medical University</institution>, <institution>Guangdong Medical University</institution>, <addr-line>Dongguan</addr-line>, <addr-line>Guangdong</addr-line>, <country>China</country>
</aff>
<author-notes>
<fn fn-type="edited-by">
<p>
<bold>Edited by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/1924503/overview">Yu-Chih Chen</ext-link>, University of Pittsburgh Medical Center, United States</p>
</fn>
<fn fn-type="edited-by">
<p>
<bold>Reviewed by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/1248703/overview">Carmela De Marco</ext-link>, Magna Gr&#xe6;cia University of Catanzaro, Italy</p>
<p>
<ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/668120/overview">Luis Enrique Gomez-Quiroz</ext-link>, Autonomous Metropolitan University, Mexico</p>
</fn>
<corresp id="c001">&#x2a;Correspondence: Shijun Zhang, <email>zhshjun@mail.sysu.edu.cn</email>; Weihong Kuang, <email>kuangwh@gdmu.edu.cn</email>
</corresp>
<fn fn-type="equal" id="fn001">
<label>
<sup>&#x2020;</sup>
</label>
<p>These authors have contributed equally to this work</p>
</fn>
</author-notes>
<pub-date pub-type="epub">
<day>28</day>
<month>09</month>
<year>2023</year>
</pub-date>
<pub-date pub-type="collection">
<year>2023</year>
</pub-date>
<volume>11</volume>
<elocation-id>1191074</elocation-id>
<history>
<date date-type="received">
<day>21</day>
<month>03</month>
<year>2023</year>
</date>
<date date-type="accepted">
<day>18</day>
<month>09</month>
<year>2023</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2023 Zhang, Li, Zheng, Liu, Hu, Zhang and Kuang.</copyright-statement>
<copyright-year>2023</copyright-year>
<copyright-holder>Zhang, Li, Zheng, Liu, Hu, Zhang and Kuang</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<p>
<bold>Background:</bold> Hepatocellular Carcinoma (HCC) is a common lethal digestive system tumor. The oxidative stress mechanism is crucial in the HCC genesis and progression.</p>
<p>
<bold>Methods:</bold> Our study analyzed single-cell and bulk sequencing data to compare the microenvironment of non-tumor liver tissues and HCC tissues. Through these analyses, we aimed to investigate the effect of oxidative stress on cells in the HCC microenvironment and identify critical oxidative stress response-related genes that impact the survival of HCC patients.</p>
<p>
<bold>Results:</bold> Our results showed increased oxidative stress in HCC tissue compared to non-tumor tissue. Immune cells in the HCC microenvironment exhibited higher oxidative detoxification capacity, and oxidative stress-induced cell death of dendritic cells was attenuated. HCC cells demonstrated enhanced communication with immune cells through the MIF pathway in a highly oxidative hepatoma microenvironment. Meanwhile, using machine learning and Cox regression screening, we identified PRDX1 as a predictor of early occurrence and prognosis in patients with HCC. The expression level of PRDX1 in HCC was related to dysregulated ribosome biogenesis and positively correlated with the expression of immunological checkpoints (PDCD1LG2, CTLA4, TIGIT, LAIR1). High PRDX1 expression in HCC patients correlated with better sensitivity to immunotherapy agents such as sorafenib, IGF-1R inhibitor, and JAK inhibitor.</p>
<p>
<bold>Conclusion:</bold> In conclusion, our study unveiled variations in oxidative stress levels between non-tumor liver and HCC tissues. And we identified oxidative stress gene markers associated with hepatocarcinogenesis development, offering novel insights into the oxidative stress response mechanism in HCC.</p>
</abstract>
<kwd-group>
<kwd>oxidative stress</kwd>
<kwd>Hepatocellular carcinoma</kwd>
<kwd>single-cell transcriptome</kwd>
<kwd>immune microenvironment</kwd>
<kwd>prognosis</kwd>
</kwd-group>
<custom-meta-wrap>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Cancer Cell Biology</meta-value>
</custom-meta>
</custom-meta-wrap>
</article-meta>
</front>
<body>
<sec id="s1">
<title>1 Introduction</title>
<p>Hepatocellular Carcinoma (HCC), the most prevalent malignant tumor of the digestive system, is the world&#x2019;s third cause of mortality from cancer (<xref ref-type="bibr" rid="B20">Ganesan and Kulik, 2023</xref>). Chronic alcohol consumption, diabetes or obesity, metabolic syndromes, and infection by Hepatitis B virus are key factors responsible for HCC progression, which promotes cirrhosis, ultimately HCC (<xref ref-type="bibr" rid="B39">Mittal and El-Serag, 2013</xref>; <xref ref-type="bibr" rid="B33">Kim and Viatour, 2020</xref>; <xref ref-type="bibr" rid="B74">Zhang et al., 2023</xref>). Now, therapeutic options for HCC are evolving from surgical treatments such as liver transplantation, surgical resection, percutaneous ablation, and radiotherapy to diversified immunotherapeutic strategies (<xref ref-type="bibr" rid="B66">Vogel et al., 2022</xref>). However, the efficacy of immunotherapy for HCC still needs to be improved and faces significant challenges. It has an association with the microenvironment of HCC.</p>
<p>The HCC microenvironment is mainly composed of cellular components such as tumor cells, tumor-infiltrating lymphocytes, and tumor-associated neutrophils, as well as noncellular components such as cytokines and chemokines (<xref ref-type="bibr" rid="B3">Anderson and Simon, 2020</xref>). The microenvironment of HCC differs greatly from that of normal liver tissues, in which inflammation is one of the leading environmental cues that mediate tumorigenesis. It has been demonstrated that acute and chronic inflammation can induce oxidative stress in the liver. During this process, hepatocytes become affected by reactive oxygen species (ROS) generated from electron leakage from mitochondrial electron transport, leading to the activation of oncogenic pathways (<xref ref-type="bibr" rid="B64">Takaki and Yamamoto, 2015</xref>). The interactions among the HCC microenvironment are also rather complex. ROS in the environment can promote malignant transformation via excessive activation of cell growth, differentiation, and survival signaling pathways such as PI3K/Akt/mTOR, and MAPK/ERK (<xref ref-type="bibr" rid="B1">Aboelella et al., 2021</xref>).</p>
<p>Oxidative stress is a circumstance that occurs when there is an imbalance between the oxidative and antioxidant effects within tissues (<xref ref-type="bibr" rid="B19">Forman and Zhang, 2021</xref>). It is not only one of the major causes of hepatic inflammatory diseases but intimately associated with the generation and progression of HCC (<xref ref-type="bibr" rid="B55">Sasaki, 2006</xref>). Our study analyzed the effect of oxidative stress on cells in the microenvironment by combining single-cell and bulk sequencing data from the non-tumor liver and HCC tissues and identified oxidative stress-related genes that have a critical impact on the survival of HCC patients.</p>
</sec>
<sec sec-type="materials|methods" id="s2">
<title>2 Materials and methods</title>
<sec id="s2-1">
<title>2.1 Data acquisition</title>
<p>Raw single-cell transcriptome profiling data for ten HCC patients from two relevant sites, primary tumor (HCC01T, HCC02T, HCC03T, HCC04T, HCC05T, HCC06T, HCC07T, HCC08T, HCC09T, and HCC10T) and adjacent non-tumor liver (HCC03N, HCC04N, HCC05N, HCC06N, HCC07N, HCC08N, HCC09N, and HCC10N), was achieved from GSE149614 dataset in Gene Expression Omnibus (GEO) database (<ext-link ext-link-type="uri" xlink:href="https://www.ncbi.nlm.nih.gov/geo/">https://www.ncbi.nlm.nih.gov/geo/</ext-link>). Bulk RNA-seq data of HCC patients were collected as follows, TCGA-LIHC dataset from The Cancer Genome Atlas (<ext-link ext-link-type="uri" xlink:href="https://portal.gdc.cancer.gov/repository">https://portal.gdc.cancer.gov/repository</ext-link>) database, HCCDB18 dataset from Integrative Molecular Database of Hepatocellular Carcinoma (<ext-link ext-link-type="uri" xlink:href="http://lifeome.net/database/hccdb/download.html">http://lifeome.net/database/hccdb/download.html</ext-link>) database, and GSE datasets (GSE76427, GSE54236, GSE36376, GSE69715, GSE121248, GSE107170, and GSE45267) from GEO database. 110 normal liver samples RNA-seq data were retrieved from Genotype-Tissue Expression (GTEx, <ext-link ext-link-type="uri" xlink:href="https://gtexportal.org/home/">https://gtexportal.org/home/</ext-link>) database. The samples information in all data sets can be seen in <xref ref-type="sec" rid="s11">Supplementary Table S1</xref>.</p>
</sec>
<sec id="s2-2">
<title>2.2 Data processing</title>
<p>We used &#x201c;Seurat&#x201d; packages (<xref ref-type="bibr" rid="B25">Hao et al., 2021</xref>) in R software to process the single cell data. Gene number, relative hemoglobin, and mitochondrial and ribosomal abundance (<xref ref-type="sec" rid="s11">Supplementary Figure S1</xref>), indicating that the cellular readouts were comparable between samples and no transcriptional batch effects were observed. Cells with &#x3c;1,500 or &#x3e;20,000 detected genes containing mitochondrial genome &#x3e;5% were excluded. Indicating that the cellular readouts were comparable between samples and no transcriptional batch effects were observed. Cells with &#x3c;2,500 or &#x3e;20,000 detected genes containing mitochondrial genome &#x3e;4% were excluded. Next, single-cell data were normalized, and variable genes were hunted by the &#x201c;SCTransform&#x201d; method. After, 20 most powerful principal components were found by PCA analysis (<xref ref-type="sec" rid="s11">Supplementary Figure S2</xref>). Further dimension reduction of those principal components was proceeded by the UMAP method to visualize cell distribution. Cell types of principal components were annotated by &#x201c;CellMarker&#x201d; (<ext-link ext-link-type="uri" xlink:href="http://xteam.xbio.top/CellMarker/">http://xteam.xbio.top/CellMarker/</ext-link>) and &#x201c;PanglaoDB&#x201d; (<ext-link ext-link-type="uri" xlink:href="https://panglaodb.se/">https://panglaodb.se/</ext-link>) databases. Cell-cell communication were conducted by &#x201c;CellChat&#x201d; R package. In addition, Bulk RNA-sequencing expression datasets were normalized by log2 (FPKM&#x2b;1) through &#x201c;limma&#x201d; package in R.</p>
</sec>
<sec id="s2-3">
<title>2.3 Pathway analysis</title>
<p>The verified pathways containing gene sets provided in the Molecular Signatures database were utilized by Gene Set Variation Analysis (GSEA) (<xref ref-type="bibr" rid="B40">Mo et al., 2003</xref>) to analyze the biological functions of single-cell data. Gene-related differential expression biological processes in transcriptome data were analyzed by single-sample Gene Set Variation Analysis (ssGSEA) (<xref ref-type="bibr" rid="B53">Rooney et al., 2015</xref>; <xref ref-type="bibr" rid="B73">Zhang et al., 2021b</xref>). Metascape (a gene annotation and analysis resource, <ext-link ext-link-type="uri" xlink:href="https://metascape.org/">https://metascape.org/</ext-link>) and molecular complex detection (MCODE) (<xref ref-type="bibr" rid="B44">Osterman et al., 2020</xref>) methods analyzed oxidative stress-related genes&#x2019; interactions and functional pathways.</p>
</sec>
<sec id="s2-4">
<title>2.4 Analysis of cell&#x2013;cell communications</title>
<p>CellChat (<xref ref-type="bibr" rid="B31">Jin et al., 2021</xref>) toolkit in R enables the analysis and interpretation of cell-cell communication within complex biological systems. Using CellChat, the gene expression profiles are analyzed to identify ligand-receptor pairs between different cell types. CellChat provides a comprehensive database of known ligand-receptor interactions, which is used to identify potential communication channels between cell types. It evaluates the significance of ligand-receptor pairs in cell-cell interactions using correlation analysis (<xref ref-type="bibr" rid="B13">Cowen et al., 2017</xref>; <xref ref-type="bibr" rid="B52">Ronen and Akalin, 2018</xref>; <xref ref-type="bibr" rid="B62">Szklarczyk et al., 2019</xref>). Once the ligand-receptor pairs are identified, CellChat analyzes the signaling pathways associated with these interactions. We utilize information from the secreted signaling pathways database (<xref ref-type="bibr" rid="B32">Jin et al., 2020</xref>) in CellChat to determine the ligand-receptor interactions in intercellular communication.</p>
</sec>
<sec id="s2-5">
<title>2.5 Screening and evaluation of oxidative stress response-related gene markers with diagnostic value by multiple machine learning algorithms</title>
<p>Due to the relatively small number of non-tumor liver tissue samples in TCGA-LIHC dataset compared to HCC samples, we used &#x201c;Sva&#x201d; package to merge the normalized GTEX dataset with the TCGA dataset and remove batch effects. The two datasets after removal of batch effects are shown in <xref ref-type="sec" rid="s11">Supplementary Figure S3</xref>. Model building was based on the oxidative stress-related genes expression profile of merged dataset. The samples in the merged dataset were randomly split into training sets and test sets in the proportion 7:3, respectively. First, we applied machine learning algorithms, including extreme gradient boosting (XGB) (<xref ref-type="bibr" rid="B35">Li et al., 2023</xref>), support vector machine (SVM) (<xref ref-type="bibr" rid="B30">Huang et al., 2023</xref>), generalized linear model (GLM) (<xref ref-type="bibr" rid="B68">Wang et al., 2023</xref>), and random forest (RF) (<xref ref-type="bibr" rid="B60">Su et al., 2023</xref>), to create models that screened for significant oxidative stress-related gene feature variables. All machine learning methods used default settings to generate models. The grid search function in the &#x201c;caret&#x201d; R package was used to modify model parameters automatically, which were tested using 5-fold cross-validation. Secondly, we interpreted the four machine learning models obtained above using the explaining features function of the &#x201c;Dalex&#x201d; R package. The explaining features, including model performance analysis and variable importance analysis, were then used to analyze the four models described above. Model performance analysis visualized the performance distribution of the four models. The models&#x2019; cumulative residual and box plot distribution diagrams were drawn, respectively. The variable importance analyzes the relative importance of different variables in the model to the model&#x2019;s prediction. It explains the impact of missing the variable on the prediction value of the response variable through the root mean square error loss function. Thirdly, the area under the curve was obtained by receiver operating characteristic curves (ROC) analysis to identify the best machine-learning model. The top six significant variable features from the optimal model were considered diagnostic gene markers for predicting the occurrence of HCC. Finally, for clinical usability, we used these diagnostic gene markers to conduct nomogram model construction and to judge their prediction error from the actual situation through the calibration curves. Additionally, the prediction performance of the diagnostic gene markers was examined by seven external independent cohorts, including GSE76427, GSE54236, GSE36376, GSE69715, GSE121248, GSE107170, and GSE45267.</p>
</sec>
<sec id="s2-6">
<title>2.6 Prognostic value analysis of PRDX1 in HCC</title>
<p>We further analyzed six oxidative stress-related gene markers (GPX4, HMOX1, PRDX1, FOS, PRDX5, and TXN) with the diagnostic value, which from the machine learning analysis steps. To judge whether they also play a role in predicting the prognosis of HCC patients. Univariate and multivariate Cox regression analyses were performed for these six genes based on survival and gene expression information of HCC patients in the TCGA cohort. After screening, PRDX1 was correlated with the prognostic survival status of HCC patients. The patients with HCC were then classified into high and low-expression groups by median cut-off value, using Kaplan-Meier survival estimate (KM) and time-dependent ROC analysis to assess whether PRDX1 was a prognostic factor. The survival analysis results were finally validated using an independent HCCDB18 cohort.</p>
</sec>
<sec id="s2-7">
<title>2.7 Correlation analysis between PRDX1 and immune microenvironment of HCC</title>
<p>To explore the correlation of PRDX1 with the immune microenvironment in HCC. We used six algorithms [CIBERSORT (<xref ref-type="bibr" rid="B11">Chen et al., 2018</xref>), CIBERSOR-ABS (<xref ref-type="bibr" rid="B67">Wang et al., 2020</xref>), QUANTISEQ (<xref ref-type="bibr" rid="B47">Plattner et al., 2020</xref>), MCP-counter (<xref ref-type="bibr" rid="B72">Zhang et al., 2021a</xref>), XCELL (<xref ref-type="bibr" rid="B4">Aran et al., 2017</xref>), and TIMER (<xref ref-type="bibr" rid="B36">Li et al., 2017</xref>)] for immune cell infiltration analyses to assess HCC individuals with the different expression level of PRDX1. Differences in immune function between different PRDX1 expression groups were then analyzed using the &#x201c;GSVA&#x201d; package.</p>
</sec>
<sec id="s2-8">
<title>2.8 Statistical analysis</title>
<p>The analyses of our study were all employed by R 4.1.1 software. Analyses used a false discovery rate (FDR) &#x3c; 0.05 from the <italic>p</italic>-value, which was adjusted by the Bonferroni method. <xref ref-type="fig" rid="F1">Figure 1</xref> displays a flow chart outlining our study.</p>
<fig id="F1" position="float">
<label>FIGURE 1</label>
<caption>
<p>Flow chart of our study.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g001.tif"/>
</fig>
</sec>
</sec>
<sec sec-type="results" id="s3">
<title>3 Results</title>
<sec id="s3-1">
<title>3.1 Landscape of the cell composition in non-tumor and HCC tissues</title>
<p>The GSE149614 dataset was utilized for single-cell analysis in our study. After quality control for scRNA-seq data, we filtered out 28,687 cells in tumor-adjacent noncancerous tissues (control) and 34,414 cells in HCC tissues for further study. We characterized the cellular landscape using cell classification marker genes identified in previous studies (<xref ref-type="bibr" rid="B52">Ronen and Akalin, 2018</xref>) (<xref ref-type="sec" rid="s11">Supplementary Figure S4</xref>). Following, seven cell types, including dendritic cells, gamma delta T cells, mucosal&#x2212;associated invariant T cells, T memory cells, B cells, and hepatocytes or malignant hepatocyte cells, were identified from the landscape (<xref ref-type="fig" rid="F2">Figure 2A</xref>). When we compared cell type proportions (<xref ref-type="fig" rid="F2">Figure 2B</xref>) between non-tumor liver tissues and HCC tissues, we discovered that the ratio of mucosal-associated invariant T cell, T memory cell, and gamma delta T cell in HCC tissues were significantly decreased. In contrast, the proportion of B cells increased in HCC tissues.</p>
<fig id="F2" position="float">
<label>FIGURE 2</label>
<caption>
<p>Single-cell profiling of HCC and adjacent non-tumor samples. <bold>(A)</bold> UMAP distribution of cell types in HCC <italic>versus</italic> non-tumor (control) tissues. <bold>(B)</bold> Contrasting differences in cell ratios in the two tissues.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g002.tif"/>
</fig>
</sec>
<sec id="s3-2">
<title>3.2 Oxidative stress of cell clusters between non-tumor and HCC samples</title>
<p>To investigate the oxidative stress characteristics of non-malignant samples and HCC samples, oxidative stress AUC (oxidative stress scoring for each cell) was generated based on the expression profile of genes in oxidative stress response collected from the Molecular Signatures database, which summarized genes involved in oxidative stress from validated experimental studies (<xref ref-type="sec" rid="s11">Supplementary Table S2</xref>). The AUCell R package was used to determine each cell line&#x2019;s oxidative stress AUC activity based on the differential expression level of oxidative stress-related genes in each cell type. Cells expressing higher oxidative stress AUC values in HCC samples were mainly in T memory cells, dendritic cells, and malignant hepatocytes, colored in yellow (<xref ref-type="fig" rid="F3">Figures 3A, B</xref>). As mucosal-associated invariant T cell, T memory cell, and gamma delta T cell clusters were remarkably decreased in the non-tumor group, colored in purple. It can be seen that the oxidative stress AUC of the cells was generally higher in the HCC samples than in the non-tumor liver tissues of the control group in the boxplot (<xref ref-type="fig" rid="F3">Figure 3C</xref>). This means that cells in the HCC microenvironment experienced more severe oxidative stress than non-tumor tissues.</p>
<fig id="F3" position="float">
<label>FIGURE 3</label>
<caption>
<p>Oxidative stress AUC of cell clusters between the HCC and non-tumor tissues. <bold>(A)</bold> UMAP plot of oxidative stress AUC in non-tumor tissues. <bold>(B)</bold> UMAP plot of oxidative stress AUC in HCC tissues. <bold>(C)</bold> Comparison of oxidative stress AUC of cell clusters between non-tumor tissues and HCC tissues.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g003.tif"/>
</fig>
<p>Gene set enrichment analyses were performed to explore the biological processes changes of these cell clusters. In the group of HCC, antigen processing via the MHC class II route and extrinsic apoptosis of T memory cells were triggered. Immune cell receptor pathways were blocked in T memory cells <xref ref-type="sec" rid="s11">Supplementary Figure S5A</xref>). In mucosal-associated invariant T cells from the tumor group, peptidase activity, catabolic process, and cellular response to stress were elevated, and innate immune response, adaptive immune response, and defense response were suppressed (<xref ref-type="sec" rid="s11">Supplementary Figure S5B</xref>). The biological function analysis results revealed that the microtubule-based process, apoptotic process, and response to heat were remarkably activated, while the immune response regulating cell surface receptor signaling pathway and cell recognition were inhibited in the gamma delta T cells of the HCC group (<xref ref-type="sec" rid="s11">Supplementary Figure S5C</xref>). The metabolic process was enhanced in dendritic cells of the HCC group, but the response to growth factor, regulation of lymphocyte activation, and cell activation were repressed (<xref ref-type="sec" rid="s11">Supplementary Figure S5D</xref>). The response to endothelial reticulum stress and monocarboxylic acid metabolic process were greatly stimulated in the B cells of the tumor group, whereas cytoplasmic translation and biosynthetic process were significantly suppressed (<xref ref-type="sec" rid="s11">Supplementary Figure S5E</xref>). Compared to non-tumor hepatocytes, malignant hepatocytes have markedly active cell proliferation and differentiation pathways, including ribonucleoprotein complex subunit organization, electron transport chain, and aerobic respiration. In addition, malignant hepatocytes exhibited suppressed lymphocyte activation, immunological response, and defensive response (<xref ref-type="sec" rid="s11">Supplementary Figure S5F</xref>).</p>
</sec>
<sec id="s3-3">
<title>3.3 Comparison of cell-cell communication between adjacent non-tumor tissues and HCC</title>
<p>Since there were apparent differences in the levels of oxidative stress between HCC cells and adjacent non-tumor tissue cells, we further compared the situations of intercellular communication in the two tissues. According to the preliminary clustered cell-cell communication network analysis results, the interaction strength and net number of interactions between malignant hepatocytes cells and immune cells communication were superior to those between non-tumor hepatocytes cells and immune cells (<xref ref-type="fig" rid="F4">Figures 4A, B</xref>; <xref ref-type="sec" rid="s11">Supplementary Figure S6</xref>). Next, we performed a Laplacian clustering analysis of signaling pathways involved in intercellular communication based on functional and structural similarities (<xref ref-type="fig" rid="F4">Figures 4C, D</xref>). Herein we focus on the functional similarity (two signaling pathways or two ligand-receptor pairs with similar roles) of intercellular communication. Inflammation and immune cell chemotaxis signaling pathways (such as IFN&#x2212;II, TNF, IL16, IL10, and CXCL) were included in groups 1 and 2. In group 3, MIF, MK, FN1, and Galectin pathways for communication and migration between immune cells and malignant hepatocytes cells. Group 4 mainly involved the intra and exocrine pathways (ANGPTL, GDF) in HCC. Our analysis of signaling pathways in cell populations identified three synergistic patterns of efferent (<xref ref-type="fig" rid="F4">Figure 4E</xref>) and afferent signaling (<xref ref-type="fig" rid="F4">Figure 4F</xref>). The inflammation pathways were the synergistic efferent signaling pathways of T memory cells of adjacent non-tumor tissue and gamma delta T cells, T memory cells, mucosal-associated invariant T cells, and B cells from both tissues. In efferent immune inflammatory response pathways, dendritic cells of adjacent non-tumor tissue and T memory cells of HCC tissue communicate synergistically. Inflammatory pathways were coordinately afferent in T memory cells of adjacent non-tumor tissue, B cells, gamma delta T cells, and mucosal&#x2212;associated invariant T cells. Dendritic cells of adjacent non-tumor tissue and T memory cells of HCC tissue had synergistic immune chemotactic afferent pathways. Tumor growth and differentiation pathways were coordinately afferent in malignant hepatocytes cells.</p>
<fig id="F4" position="float">
<label>FIGURE 4</label>
<caption>
<p>Intracellular communication between HCC and immune cells. <bold>(A)</bold> Interaction of cells in adjacent non-tumor tissue and HCC tissue. The thickness of the line indicates the number of connections or interaction strength, and the arrow indicates the direction of communication. <bold>(B)</bold> Heatmaps displayed the number and strength of the interactions. <bold>(C)</bold> Functional similarity or <bold>(D)</bold> structural similarity classification of shared communication pathways between cells. <bold>(E)</bold> Patterns of functional similarities signaling of secretory cells outcoming or <bold>(F)</bold> incoming to target cells.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g004.tif"/>
</fig>
<p>Further, by comparing outgoing and incoming interaction strength in non-tumor and HCC tissues, we identified significant changes in the signals sent or received by T memory cells, B cells, and malignant hepatocytes (<xref ref-type="fig" rid="F5">Figure 5A</xref>). The memory T cells and B cells in the control group mainly served as signal receivers in cell communication, while the memory T cells and B cells in HCC mainly served as signal transmitters. In HCC, malignant hepatocytes send a higher intensity of intercellular communication signals than non-neoplastic hepatocytes in the control group. The dot plot visually represents the dominant senders and receivers of intercellular communication. The <italic>X</italic> and <italic>Y</italic>-axes correspond to the total outgoing and incoming communication probabilities, respectively, for each cell group. The size of the dots indicates the number of inferred links associated with each cell block, considering both outgoing and incoming interactions. Larger dots indicate a higher number of links. The colors of the dots differentiate between different cell groups, allowing for identification and comparison. Interestingly, we discovered that only the MIF pathway was significantly enriched in non-neoplastic and neoplastic contexts (<xref ref-type="fig" rid="F5">Figure 5B</xref>). Each cell cluster exhibited significant MIF pathway communication in incoming (<xref ref-type="fig" rid="F5">Figure 5C</xref>) and outgoing (<xref ref-type="fig" rid="F5">Figure 5D</xref>) modes under non-tumor and HCC conditions. In light of the above findings, we further investigated the communication between HCC cells and hepatocytes or immune cells through receptor-ligand interaction studies (<xref ref-type="fig" rid="F5">Figure 5E</xref>). The results indicated that malignant hepatocytes and immune cells, including B cells, dendritic cells, gamma delta T cells, mucosal&#x2212;associated invariant T cells, and T memory cells interact via CD74-CXCR4. Second, HCC cells interact with dendritic cells, gamma delta T cells, mucosal&#x2212;associated invariant T cells, and T memory cells through CD74<sup>&#x2212;</sup>CD44. However, no relevant communication between HCC cells and adjacent non-tumor hepatocytes has been found in MIF signaling. Strikingly, MIF communication was significantly more potent in the HCC environment than in the non-tumor environment (<xref ref-type="fig" rid="F6">Figures 6A, B</xref>). The width of the edges in the graph is determined by the number of interactions, which reflects the number of ligand-receptor pairs involved in the communication between two interacting cell clusters. A wider edge indicates a higher number of interactions between the cells. In the HCC state of the MIF signaling pathway (<xref ref-type="fig" rid="F6">Figure 6C</xref>), malignant hepatocytes serve as signal senders. Gamma delta T cells, mucosal&#x2212;associated invariant T cells, and T memory cells were recipients. Dendritic cells and mucosal&#x2212;associated invariant T cells act as mediators. B cells and mucosal&#x2212;associated invariant T cells were the influencers. In contrast, non-neoplastic hepatocytes in the non-tumor state communicate significantly much weaker with immune cells (<xref ref-type="fig" rid="F6">Figures 6D&#x2013;F</xref>).</p>
<fig id="F5" position="float">
<label>FIGURE 5</label>
<caption>
<p>Intercellular communication signaling changes between non-tumor tissue and HCC tissue. <bold>(A)</bold> Cells&#x2019; outgoing and incoming interaction strength was analyzed in non-neoplastic and HCC environments. The difference in the size of the dots in the two environments represents the set of cells that have changed sending or receiving signals. <bold>(B)</bold> The information flow changes of signaling pathways between non-tumor and HCC status. <bold>(C)</bold> Incoming and <bold>(D)</bold> outcoming signaling expression differences of cell clusters under the two environments are demonstrated by heatmaps. <bold>(E)</bold> HCC cells have significant ligand-receptor interactions of MIF pathway with immune cells.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g005.tif"/>
</fig>
<fig id="F6" position="float">
<label>FIGURE 6</label>
<caption>
<p>MIF signaling pathway changes between the non-tumor environment and the HCC environment. <bold>(A,B)</bold> Network diagrams of malignant hepatocyte cells communicating with immune cells through ligand receptors of MIF signaling pathway. <bold>(C)</bold> Functional roles in cell-cell communication played by cells in HCC status. The darker the color, the more deterministic the role is. <bold>(D,E)</bold> Network diagrams of non-tumor hepatocyte cells communicating with immune cells through ligand receptors of MIF signaling pathway. <bold>(F)</bold> Functional roles in cell-cell communication played by cells in non-tumor status. The darker the color, the more deterministic the role is.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g006.tif"/>
</fig>
</sec>
<sec id="s3-4">
<title>3.4 Identification of oxidative stress response-related hub genes in HCC</title>
<p>Next, differentially expressed oxidative stress response-related genes (DEGs) of each cell type between non-tumor samples and HCC samples were marked in the volcano and bar plot (<xref ref-type="sec" rid="s11">Supplementary Figures S7A, B</xref>; <xref ref-type="sec" rid="s11">Supplementary Table S3</xref>). These DEGs were further subjected to MCODE analysis to screen hub genes of oxidative stress response in the pathogenesis of HCC. The MCODE analysis determined that HMOX1, POR, SOD1, PRDX6, P4HB, GPX4, PRDX3, PRDX5, JUN, PRDX2, TXN, FOS, and PRDX1 were the oxidative stress-related hub genes among DEGs (<xref ref-type="fig" rid="F7">Figure 7A</xref>). Metascape analysis further revealed that the genes HMOX1, POR, JUN, and FOS play a role in regulating the p53 pathway as hub genes. Other hub genes regulate oxidative stress response through the ROS pathway. All the DEGs were associated with the ROS pathway, TNFA signaling via NFKB, apoptosis, hypoxia, and mTORC1 signaling pathway (<xref ref-type="fig" rid="F7">Figure 7B</xref>). This analysis provided evidence of the involvement of these genes in critical biological processes of HCC. Using cBioPortal (<xref ref-type="bibr" rid="B10">Cerami et al., 2012</xref>; <xref ref-type="bibr" rid="B21">Gao et al., 2013</xref>) tools in the TCGA cohort, we further investigated the mutational landscape of these 13 hub genes in HCC. Chromosome mapping revealed that chromosomes 1 and 19 contain the most significant number of dysregulated oxidative stress-related hub genes in HCC. In contrast, no X and Y chromosomes contain dysregulated oxidative stress-related hub genes (<xref ref-type="fig" rid="F7">Figure 7C</xref>). We analyzed the somatic cell mutation spectrum of 366 patients with HCC to determine the mutation rate of these hub genes. Among the hub genes in HCC patients, PRDX6, P4HB, and POR showed the most significant amplified genetic alteration rates of 9%, 5%, and 1.9%, respectively. PRDX1 displayed a high structural variation rate of 5%. It was observed that FOS had a deep deletion rate of 1.3%. The remaining hub genes exhibited minimal mutation rates below 0.5% in HCC patients (<xref ref-type="fig" rid="F7">Figure 7D</xref>). These findings shed light on the mutational landscape of the hub genes associated with oxidative stress response in HCC, highlighting specific genes with significant genetic alterations.</p>
<fig id="F7" position="float">
<label>FIGURE 7</label>
<caption>
<p>The hallmark pathways and genetic alterations analysis of the oxidative stress-related DEGs in HCC. <bold>(A)</bold> PPI network for hub genes related to oxidative stress among DEGs. Hub genes were colored green and blue. <bold>(B)</bold> The hallmark pathways enrichment analysis of the oxidative stress-related DEGs. <bold>(C)</bold> Circular visualization of chromosomal positions of 13 hub genes. <bold>(D)</bold> The genetic alteration profiles of the 13 hub genes.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g007.tif"/>
</fig>
</sec>
<sec id="s3-5">
<title>3.5 Screening and verification of diagnostic markers</title>
<p>Since the oxidative stress response level was significantly different between non-tumor tissues and HCC tissue cells, based on the bulk transcript data, we further analyzed the diagnostic value of oxidative stress response-related hub genes by four machine learning models (RF, SVM, XGB, GLM). The RF and SVM models performed the lowest residual values (<xref ref-type="fig" rid="F8">Figures 8A, B</xref>). Meanwhile, the top 10 ranked gene variables in the four machine learning models were filtered out by root mean square error (<xref ref-type="fig" rid="F8">Figure 8C</xref>). By visual ROC analysis, the RF and SVM models also had the highest AUC (0.981) in 5-fold cross-validation (<xref ref-type="fig" rid="F8">Figure 8D</xref>). Then, in conjunction with these outcomes, six oxidative stress response-related gene markers (GPX4, HMOX1, PRDX1, FOS, PRDX5, and TXN) with the highest diagnostic value were chosen from the RF and SVM model (<xref ref-type="sec" rid="s11">Supplementary Table S4</xref>). Further, we constructed a diagnostic nomogram based on these six gene markers to test their clinical decision-making efficiency in predicting the early occurrence of HCC (<xref ref-type="fig" rid="F9">Figure 9A</xref>). The calibration curve analysis showed that the accuracy of the nomogram model in predicting the occurrence risk of HCC was very close to the actual sample probability (<xref ref-type="fig" rid="F9">Figure 9B</xref>). The decision curve analysis reveals that this nomogram is highly accurate with a considerable net benefit (<xref ref-type="fig" rid="F9">Figure 9C</xref>). Additionally, the effectiveness of our nomogram model and gene markers has been verified in seven external datasets by ROC analysis (GSE76427, AUC: 0.935; GSE54236, AUC: 0.828; GSE36376, AUC: 0.963; GSE69715, AUC: 1.000; GSE121248, AUC: 0.974; GSE107170, AUC: 0.883; GSE45267, AUC: 0.974; Training cohort, AUC: 0.993) (<xref ref-type="fig" rid="F9">Figure 9D</xref>, <xref ref-type="sec" rid="s11">Supplementary Figure S8</xref>). The differences in single-cell levels of these six genes between non-neoplastic and malignant hepatocytes were consistent with the transcriptome analysis (<xref ref-type="fig" rid="F9">Figures 9E, F</xref>). Additionally, we investigated the expression of these genes in immunohistochemical pathological sections from The Human Protein Atlas (<ext-link ext-link-type="uri" xlink:href="http://www.proteinatlas.org/">www.proteinatlas.org/</ext-link>) and found that they were highly expressed, further supporting their potential as biomarkers (<xref ref-type="sec" rid="s11">Supplementary Figure S9</xref>). These results suggested that these six gene diagnostic markers can effectively identify early-stage HCC individuals.</p>
<fig id="F8" position="float">
<label>FIGURE 8</label>
<caption>
<p>Machine learning model construction and evaluation. <bold>(A)</bold> Each machine learning model&#x2019;s cumulative residual distribution. <bold>(B)</bold> Boxplots were used to display the residuals of machine learning models. The red dot shows the residuals&#x2019; root mean square. <bold>(C)</bold> Genes that are significant in machine learning models. <bold>(D)</bold> ROC analysis for four machine learning models in the testing cohort.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g008.tif"/>
</fig>
<fig id="F9" position="float">
<label>FIGURE 9</label>
<caption>
<p>Machine learning-based nomogram model validation. <bold>(A)</bold> Building a nomogram to forecast the risk of HCC. <bold>(B)</bold> Calibration curve analysis for nomogram. <bold>(C)</bold> Decision curve analysis for nomogram. <bold>(D)</bold> ROC analysis for the nomogram model in testing and training cohorts. <bold>(E)</bold> Expression of six gene signatures in non-neoplastic hepatocytes. <bold>(F)</bold> Expression of six gene signatures in malignant hepatocytes.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g009.tif"/>
</fig>
</sec>
<sec id="s3-6">
<title>3.6 Oxidative stress response-related diagnostic marker PRDX1 was associated with prognosis in HCC</title>
<p>We further performed survival analysis for the six oxidative stress-related diagnostic gene markers from above steps to observe their associations with HCC prognostic progression. Among them, the expression levels of HMOX1, PRDX1, and TXN were significantly related to overall survival in univariate Cox regression analysis of the TCGA-LIHC cohort (<italic>p</italic> &#x3d; 0.004, <italic>p</italic> &#x3c; 0.001, <italic>p</italic> &#x3d; 0.029, respectively). Meanwhile, in the HCCDB18 cohort, PRDX1 and PRDX5 were markedly linked with HCC individuals&#x2019; overall survival rate by univariate cox regression analysis (<italic>p</italic> &#x3d; 0.018, <italic>p</italic> &#x3d; 0.018, respectively). Based on multivariate cox regression in two cohorts (<xref ref-type="sec" rid="s11">Supplementary Table S5</xref>), PRDX1 was identified to be the independent prognostic predictor for HCC (TCGA-LIHC: <italic>p</italic> &#x3c; 0.001, Hazard ratio &#x3d; 1.715, 95%Confidence interval &#x3d; 1.326&#x2013;2.217; HCCDB18: <italic>p</italic> &#x3d; 0.018, Hazard ratio &#x3d; 1.787, 95%Confidence interval &#x3d; 1.104&#x2013;2.892). Thus, PRDX1 was selected for further research.</p>
</sec>
<sec id="s3-7">
<title>3.7 Validation of the prognostic value of PRDX1 in HCC</title>
<p>Depending on median cut-off values, HCC patients in TCGA-LIHC and HCCDB18 were divided into high and low PRDX1 expression groups. The overall survival of HCC patients in the high PRDX1 group was considerably worse than that of patients in the low PRDX1 group, as shown by Kaplan-Meier analysis (<xref ref-type="fig" rid="F10">Figures 10A, B</xref>). We also found that HCC patients with high expression of PRDX1 have much worse progress-free intervals and disease-specific survival status (<xref ref-type="sec" rid="s11">Supplementary Figure S10</xref>). This tendency of HCC patients was also visible in the survival plot (<xref ref-type="fig" rid="F10">Figures 10C, D</xref>). In univariate cox analysis with clinicopathological characteristics, the PRDX1 was significantly related to the overall survival of HCC patients (TCGA-LIHC: Hazard ratio &#x3d; 2.449, 95%Confidence interval &#x3d; 1.452&#x2013;4.129, <italic>p</italic> &#x3c; 0.001; HCCDB18: Hazard ratio &#x3d; 2.988, 95%Confidence interval &#x3d; 1.462&#x2013;6.098, <italic>p</italic> &#x3d; 0.003) (<xref ref-type="fig" rid="F10">Figures 10E, G</xref>). Multivariate cox regression determined that the PRDX1 was an independent predictive factor for patients&#x2019; prognoses among clinicopathological characteristics (TCGA-LIHC: Hazard ratio &#x3d; 2.395, 95%Confidence interval &#x3d; 1.394&#x2013;4.115, <italic>p</italic> &#x3d; 0.002; HCCDB18: Hazard ratio &#x3d; 2.413, 95%Confidence interval &#x3d; 1.193&#x2013;4.881, <italic>p</italic> &#x3d; 0.014) (<xref ref-type="fig" rid="F10">Figures 10F, H</xref>). At the same time, the prognostic prediction power (AUC) for the PRDX1 in 1 year, 2&#xa0;years, and 3 years in the ROC analysis of two cohorts was relative satisfaction (<xref ref-type="fig" rid="F10">Figures 10I, J</xref>). Furthermore, a nomogram was created to evaluate the prognosis status of HCC patients by incorporating clinicopathological characteristics, including grade, stage, age, gender, and the expression profile of PRDX1 (<xref ref-type="fig" rid="F10">Figure 10L</xref>). The ideal fitting degree of the calibration curves to the observed values validated the accuracy of nomogram in predicting HCC patients&#x2019; outcomes (<xref ref-type="fig" rid="F10">Figures 10M, N</xref>). Moreover, we found the expression level of PRDX1 was consistently high in most HCC cell lines by Cancer Cell Line Encyclopedia (<ext-link ext-link-type="uri" xlink:href="https://sites.broadinstitute.org/ccle">https://sites.broadinstitute.org/ccle</ext-link>) (<xref ref-type="fig" rid="F10">Figure 10K</xref>). As a result, as an independent prognostic factor, PRDX1 has high clinical value in assessing the progression of HCC patients.</p>
<fig id="F10" position="float">
<label>FIGURE 10</label>
<caption>
<p>Survival analysis of PRDX1 in the two cohorts. TCGA-LIHC cohort <bold>(A,C,E,F,L,I,M)</bold>, HCCDB18 cohort <bold>(B,D,G,H,J,N)</bold>. <bold>(A,B)</bold> Kaplan&#x2013;Meier survival analysis result. <bold>(C,D)</bold> Survival status plots of HCC patients in the two cohorts. <bold>(E)</bold> Univariate independent Cox analysis for PRDX1 in TCGA-LIHC cohort. <bold>(F)</bold> Multivariate independent Cox analysis for PRDX1 in TCGA-LIHC cohort. <bold>(G)</bold> Univariate independent Cox analysis for PRDX1 in the HCCDB18 cohort. <bold>(H)</bold> Multivariate independent Cox analysis for PRDX1 in the HCCDB18 cohort. <bold>(I,J)</bold> Time-dependent ROC analysis for PRDX1 in HCC patients. <bold>(K)</bold> Expression profile of PRDX1 in various HCC cell lines. <bold>(L)</bold> The predictive nomogram. <bold>(M)</bold> Calibration curves of nomogram model of the TCGA-LIHC cohort. <bold>(N)</bold> Calibration curves of nomogram model of the HCCDB18 cohort.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g010.tif"/>
</fig>
</sec>
<sec id="s3-8">
<title>3.8 Identification pathways and biological functions of PRDX1 in HCC</title>
<p>Gene set enrichment analyses were conducted in HCC, and PRDX1 was found to be mainly involved in digestion, ribonucleoprotein complex biogenesis, ribosome biogenesis, gene silencing by RNA, and smooth muscle cell differentiation (<xref ref-type="sec" rid="s11">Supplementary Figures S11A, B</xref>). Furthermore, we explored the PRDX1-related specific biological process activation status in HCC patients. In the bubble plot, the activated PRDX1-related pathways in HCC patients mainly have ribosome biogenesis, ribonucleoprotein complex biogenesis, ncRNA processing, cellular glucuronidation, uronic acid metabolic process, snRNA processing, and regulation of programmed necrotic cell death (<xref ref-type="sec" rid="s11">Supplementary Figure S11C</xref>). In contrast, PRDX1-related pathways, including vascular-associated smooth muscle cell differentiation, smooth muscle cell differentiation, IL-6 mediated signaling pathway, endosome to plasma membrane protein transport, gene silencing by RNA, and negative regulation of transporter activity, were suppressed in HCC patients.</p>
</sec>
<sec id="s3-9">
<title>3.9 Correlation between PRDX1 and immune microenvironment in HCC</title>
<p>By integrating multiple immune cell infiltration analysis methods (Timer, Cibersort, Cibersort&#x2212;abs, Quantise, Mcpcounter, and Xcell), the abundances of immune cells, incorporated CD4<sup>&#x2b;</sup> T memory resting cell, CD4<sup>&#x2b;</sup> T central memory cell, Tregs, neutrophils, myeloid dendritic cell, and NK cells, were markedly enriched in the high-PRDX1 group than the low-PRDX1 group. Non-immune cells, such as endothelial cells, and cancer-associated fibroblast, were also significantly enriched in the high-PRDX1 group (<xref ref-type="fig" rid="F11">Figure 11A</xref>; <xref ref-type="sec" rid="s11">Supplementary Figure S12</xref>). From ESTIMATE algorithm analysis results, the immunological score and estimated score (tumor purity) of HCC patients with PRDX1 high expression were relatively high than those with low expression (<xref ref-type="fig" rid="F11">Figure 11B</xref>). Afterward, the group with high PRDX1 expression held significant T cell exclusion and microsatellite instability (MSI) (<xref ref-type="fig" rid="F11">Figures 11C, D</xref>). Meanwhile, the level of PRDX1 expression linked positively with HCC tumor mutational burden (TMB) (<xref ref-type="fig" rid="F11">Figure 11E</xref>). Moreover, using Human Protein Atlas database (<ext-link ext-link-type="uri" xlink:href="http://www.proteinatlas.org/">http://www.proteinatlas.org/</ext-link>), we discovered immunohistochemical staining intensity of PRDX1 of the HCC sample was considerably higher than the normal liver sample (<xref ref-type="fig" rid="F11">Figure 11F</xref>). Immune functions, including APC co-inhibition, HLA, MHC class I, and para-inflammation, were active in the HCC patients with high PRDX1 expression. At the same time, type II IFN response was more active in the group with low PRDX1 expression (<xref ref-type="fig" rid="F12">Figure 12A</xref>).</p>
<fig id="F11" position="float">
<label>FIGURE 11</label>
<caption>
<p>Analysis for immune landscape in two PRDX1 expression groups (&#x2a;: <italic>p</italic> &#x3c; 0.05; &#x2a;&#x2a;: <italic>p</italic> &#x3c; 0.01; &#x2a;&#x2a;&#x2a;: <italic>p</italic> &#x3c; 0.001). <bold>(A)</bold> The infiltration of immune cells in high- and low-PRDX1 HCC patients. <bold>(B)</bold> Differences in the immune, stromal, and ESTIMATE scores between low- and high-PRDX1 groups. <bold>(C)</bold> T cell exclusion score was different between the two groups. <bold>(D)</bold> Microsatellite instability was different between the two groups. <bold>(E)</bold> The correlation between the TMB and PRDX1 expression level in HCC. <bold>(F)</bold> Immunohistochemical staining intensity for PRDX1 in normal liver tissue and HCC tissue.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g011.tif"/>
</fig>
<fig id="F12" position="float">
<label>FIGURE 12</label>
<caption>
<p>The immune response and immune therapies differences between low-PRDX1 and high-PRDX1 groups (&#x2a;: <italic>p</italic> &#x3c; 0.05; &#x2a;&#x2a;: <italic>p</italic> &#x3c; 0.01; &#x2a;&#x2a;&#x2a;: <italic>p</italic> &#x3c; 0.001). <bold>(A)</bold> Immune functions analysis in two PRDX1 expression groups. <bold>(B)</bold> Differences of immune checkpoint expression between low- and high-PRDX1 groups. <bold>(C)</bold> The correlation between the expression level of immune checkpoints and PRDX1 in HCC. <bold>(D)</bold> The targeting drug sensitivity in low- and high-PRDX1 groups.</p>
</caption>
<graphic xlink:href="fcell-11-1191074-g012.tif"/>
</fig>
<p>Following, we explored the relationships between immune checkpoints and HCC patients in different PRDX1 expression groups. HCC patients in the high-PRDX1 group had elevated immune checkpoints, incorporating PDCD1LG2, CTLA4, TIGIT, LAIR1, CD86, CD47, TNFRSF9, TNFRSF18 and TNFRSF4 than the patients in the low-PRDX1 group (<xref ref-type="fig" rid="F12">Figure 12B</xref>). Increased expression levels of immune checkpoints were positively correlated with the expression of PRDX1 (<xref ref-type="fig" rid="F12">Figure 12C</xref>). It implied that HCC patients with high PRDX1 expression might benefit more from immune checkpoint inhibitor therapies. To explore suitable drugs for HCC patients with high expression of PRDX1, we used the oncoPredict R package in testing the sensitivity of drugs between two groups with differing PRDX1 expression levels, based on Cancer Therapeutics Response Portal (<ext-link ext-link-type="uri" xlink:href="http://portals.broadinstitute.org/ctrp.v2.1/">http://portals.broadinstitute.org/ctrp.v2.1/</ext-link>) and Genomics of Drug Sensitivity in Cancer (<ext-link ext-link-type="uri" xlink:href="https://www.cancerrxgene.org/">https://www.cancerrxgene.org/</ext-link>) databases (<xref ref-type="fig" rid="F12">Figure 12D</xref>). From the results, HCC patients in the high PRDX1 expression group exhibited greater sensitivity to twelve drugs, including Sorafenib (multi-kinase inhibitor), Linsitinib (IGF-1R inhibitor), JAK inhibitor (AZ960), ERK inhibitor (ERK 2440), Mitochondrial inhibitor (Dihydrorotenone), IKK inhibitor (BMS-345541), IRAK4 inhibitor (IRAK4_4710), SYK inhibitor (Entospletinib), TGF-&#x3b2; Receptor I/II inhibitor (LY2109761), MCL-1 inhibitor (AZD5991), KRAS (G12C) inhibitor, and I&#x2212;BET inhibitor (I-BET-762), than patients with low PRDX1 expression group. These pharmaceuticals could be beneficial in treating HCC patients with high PRDX1 expression.</p>
</sec>
</sec>
<sec sec-type="discussion" id="s4">
<title>4 Discussion</title>
<p>This present study systematically elucidated the differences in oxidative stress levels between the microenvironment of HCC tissues and the environment of non-tumor tissues as assessed by the AUCell score of the oxidative stress response. The results revealed that oxidative stress response of cells was higher in HCC than in the non-tumor state. Among them, the increased level of oxidative stress response in memory T cells was most notable in the setting of HCC, where antigen processing by oxidative stress and presentation of exogenous peptide antigens via MHC class II was enhanced, and extrinsic apoptosis induced by oxidative stress was also enhanced, but lymphocyte activation function and antigen receptor-mediated signaling pathways were suppressed. This indicated that oxidative stress of immune cells may be a means through which HCC escapes the immune system. In the HCC microenvironment, oxidative stress-induced cell death was attenuated in dendritic cells compared with other immune cells, indicating that it may have a stronger intracellular antioxidant capacity. Current evidence (<xref ref-type="bibr" rid="B29">Hu et al., 2021</xref>) shows that oxidative stress is indispensable for dendritic cell functional activation, and ROS-mediated DNA oxidation can enhance immune recognition by dendritic cells, which as a metabolic regulator, can promote STING-dependent dendritic cells&#x2019; antitumor immune responses. Clinical treatments with antioxidant intervention may reduce the antitumor activity of dendritic cells. Meanwhile, comparative analysis results between the intercellular communication situation in the HCC microenvironment and that in the non-tumor tissue environment showed that malignant cells communicated more significantly with immune cells through the MIF pathway. Suggesting that more intense levels of oxidative stress in the tumor microenvironment induced MIF secretion to promote HCC cell survival and immunosuppression.</p>
<p>Oxidative stress, a state of oxidative and antioxidant imbalance in the body when it undergoes excessive accumulation of harmful stimuli such as reactive oxygen species, is a critical factor in liver disease progression and hepatocarcinogenesis (<xref ref-type="bibr" rid="B7">Bartsch and Nair, 2006</xref>). Several studies have found that the level of oxidative stress in various tumors, such as gastric carcinoma, colon carcinoma, and esophageal carcinoma, is significantly higher than that in non-tumor tissues or healthy tissues, confirming a close relationship between oxidative stress and cancer formation or progression (<xref ref-type="bibr" rid="B15">Dalle-Donne et al., 2006</xref>; <xref ref-type="bibr" rid="B2">Agarwal et al., 2012</xref>; <xref ref-type="bibr" rid="B6">Bai et al., 2022</xref>). It has been summarized that under various pathological conditions, oxidative stress could be induced by ROS generated from electron leakage through mitochondrial electron transport in liver disease, thereby damaging hepatocytes, promoting pathological polyploidization, triggering inflammation, and leading to the activation of oncogenic pathways (<xref ref-type="bibr" rid="B55">Sasaki, 2006</xref>; <xref ref-type="bibr" rid="B12">Cichoz-Lach and Michalak, 2014</xref>; <xref ref-type="bibr" rid="B28">Higgs et al., 2014</xref>; <xref ref-type="bibr" rid="B56">Satapati et al., 2016</xref>).</p>
<p>Redox reactions are fundamental processes underpinning critical cellular functions like oxidative phosphorylation for energy production (<xref ref-type="bibr" rid="B42">Nath and Villadsen, 2015</xref>). Furthermore, redox changes are instrumental in cell signaling, modulating the activities of enzymes, receptors, and transcription factors through the redox state of specific cysteine residues (<xref ref-type="bibr" rid="B43">Navarro-Yepes et al., 2014</xref>). Differentiating between normal redox fluctuations and oxidative stress is nuanced and multifaceted. This distinction hinges on intricate factors, including the type of ROS, their subcellular localization, and the duration of exposure. It is important to note that transient increases in ROS during immune responses or cellular differentiation are often essential for these processes and do not constitute oxidative stress (<xref ref-type="bibr" rid="B18">Forman et al., 2010</xref>). Cellular redox balance is maintained through the collaborative efforts of enzymatic and non-enzymatic antioxidants (<xref ref-type="bibr" rid="B24">Halliwell and Gutteridge, 1986</xref>). The equilibrium between ROS and antioxidants dictates whether a redox shift remains adaptive or evolves into oxidative stress. Defining oxidative stress lacks a universal threshold due to its context-dependent nature. Researchers (<xref ref-type="bibr" rid="B48">Pouvreau, 2014</xref>; <xref ref-type="bibr" rid="B70">Wu et al., 2019</xref>; <xref ref-type="bibr" rid="B71">Zaidieh et al., 2019</xref>) have employed various indicators such as the glutathione redox ratio, ROS concentrations, or specific oxidative damage products. These thresholds can differ based on cell types, tissues, and disease conditions. Transitioning from a redox change to oxidative stress carries profound biological implications. Oxidative stress can damage lipids, proteins, and nucleic acids, resulting in mutations, cellular dysfunction, and the initiation of inflammatory cascades (<xref ref-type="bibr" rid="B26">Harrington et al., 2023</xref>).</p>
<p>The basal oxidative state is a cornerstone of cellular biology, serving as a linchpin in cellular signaling. ROS act as vital signaling molecules when present in controlled quantities, participating in cell proliferation, differentiation, and apoptosis processes (<xref ref-type="bibr" rid="B5">Bae et al., 2011</xref>). Key transcription factors like NF-&#x3ba;B and Nrf2, which modulate inflammation and antioxidant defenses, are sensitive to redox changes. Across diverse cell types and organelles, the basal oxidative state exhibits variations. For example, renowned for their redox activity, mitochondria meticulously regulate ROS production and elimination to optimize their function (<xref ref-type="bibr" rid="B51">Rigoulet et al., 2011</xref>). Typically, intracellular ROS concentrations fall within the picomolar to low nanomolar range, underscoring the necessity for precise regulation (<xref ref-type="bibr" rid="B22">Gupta et al., 2014</xref>). Cells employ a complex network of antioxidant systems to preserve the basal oxidative state. This network encompasses enzymatic antioxidants and non-enzymatic antioxidants. These antioxidants collaborate to scavenge surplus ROS and uphold redox equilibrium. Departures from the basal oxidative state can have far-reaching consequences for cellular processes. Elevated ROS levels can lead to oxidative damage to biomolecules, inducing DNA mutations, protein misfolding, and lipid peroxidation. Conversely, an overly reduced environment can disrupt redox-sensitive signaling pathways, impair immune responses, and contribute to disease pathogenesis (<xref ref-type="bibr" rid="B41">Nakamura et al., 1997</xref>). Dysregulation of redox balance underpins a multitude of pathological conditions. Chronic oxidative stress is implicated in cancer. A comprehensive understanding of and interventions targeting the basal oxidative state hold profound clinical implications for disease management and prevention.</p>
<p>To further explore the possible impact of oxidative stress levels on cellular crosstalk, we contrasted the strength of intercellular communication in a non-tumor environment with low <italic>versus</italic> a tumor environment with higher levels of oxidative stress. Interestingly, in an analysis of intercellular communication, this study found that the communication strength between malignant and immune cells in the MIF pathway was significantly greater in the setting of HCC with higher levels of oxidative stress than in the setting of non-tumor hepatocytes. MIF is a pleiotropic cytokine overexpressed in many tumors and has pro-inflammatory and tumor-promoting activities (<xref ref-type="bibr" rid="B9">Bucala, 2012</xref>). Studies have shown that MIF can affect the migration of tumor cells and inhibit immune cell infiltration into tumor tissue, affecting tumor cells and tumor stroma through multiple mechanisms (<xref ref-type="bibr" rid="B59">Simpson et al., 2012</xref>; <xref ref-type="bibr" rid="B46">Pasupuleti et al., 2014</xref>). There were evidences that a variety of immune and non-immune cells, including T cells, macrophages, dendritic cells, and epithelial cells, upon stimulation by noxious factors such as hypoxia and UV irradiation, secretes MIF (<xref ref-type="bibr" rid="B54">Sakamoto et al., 2002</xref>; <xref ref-type="bibr" rid="B58">Simons et al., 2011</xref>; <xref ref-type="bibr" rid="B27">Heise et al., 2012</xref>; <xref ref-type="bibr" rid="B37">Merk et al., 2012</xref>). Currently, it is unclear how MIF is modulated in tumor. The complexity of MIF in cancer emphasizes the necessity of gaining a deeper understanding of its biological function. <xref ref-type="bibr" rid="B23">Gupta et al. (2016)</xref> found that the regulation of p53 did not induce MIF secretions in renal, breast, and lung cancerous cells, but oxidative stress was a mediator of the stimulator of MIF secretions. The CD74<sup>&#x2212;</sup>CD44 receptor complex and the chemokine receptor CXCR4 activated MIF signaling, which in different types of cells activates both anti-apoptotic and pro-survival pathways via MAPK, Akt, and SRC pathways (<xref ref-type="bibr" rid="B34">Leng et al., 2003</xref>; <xref ref-type="bibr" rid="B57">Shi et al., 2006</xref>; <xref ref-type="bibr" rid="B8">Bernhagen et al., 2007</xref>; <xref ref-type="bibr" rid="B38">Mitchell and Yaddanapudi, 2014</xref>). <xref ref-type="bibr" rid="B63">Takahashi et al. 1(998)</xref> found that inhibition of endogenous MIF expression could slow the growth rate of tumor cells, and knockdown of MIF inhibited HCC cells proliferation. <xref ref-type="bibr" rid="B69">Wirtz et al. (2021)</xref> experimentally demonstrated that inhibition of the MIF/CD74 axis, which induces HCC cell death and activates ERK, can reduce the number of tumors and the proliferation rate. These are consistent with our findings. Although some progress has been made in the current study on MIF regulation of immune responses and inflammatory responses in cancer, its biological functions related to oxidative stress need to be further explored.</p>
<p>Based on the close relationship between oxidative stress and tumorigenesis and the significant difference in oxidative stress between HCC tissues and HCC tissues, we analyzed the hub genes of oxidative stress-related DEGs in cells to provide more clues for clinical decision-making. The thirteen oxidative stress-related hub genes are HMOX1, POR, SOD1, PRDX6, P4HB, GPX4, PRDX3, PRDX5, JUN, PRDX2, TXN, FOS, and PRDX1. They were significantly enriched in TNF, apoptosis, hypoxia, and mTOR pathways, in addition to their significant expression in ROS pathways. Previous studies have revealed that machine learning with multivariate analysis, which considers the correlations between factors, has a lower error rate than univariate analysis and can vastly boost the precision of forecasting tumor susceptibility (<xref ref-type="bibr" rid="B14">Cruz and Wishart, 2007</xref>; <xref ref-type="bibr" rid="B45">Painuli et al., 2022</xref>). In this study, we included four machine learning models (RF, GLM, SVM, and XGB) validated to have robust classification ability (<xref ref-type="bibr" rid="B65">Tan et al., 2014</xref>; <xref ref-type="bibr" rid="B50">Rigatti, 2017</xref>; <xref ref-type="bibr" rid="B75">Zopluoglu, 2019</xref>; <xref ref-type="bibr" rid="B16">de Melo et al., 2022</xref>). Since the RF <italic>versus</italic> SVM model had the equal highest predictive power (AUC &#x3d; 0.981) in the test cohort, we selected the utmost important six feature gene variables (GPX4, HMOX1, PRDX1, FOS, PRDX5, and TXN) in both models. Then we constructed a nomogram model for the clinical diagnosis of HCC based on these six genes. In both the calibration curves and the evaluation in three external validation sets (AUC &#x3d; 0.974, 0.883, 0.974), our nomogram model effectively predicted HCC. Therefore, the nomogram obtained by screening six oxidative stress-related genes through multiple machine learning algorithms was a reliable indicator for evaluating the pathological outcomes of patients, providing new insights into the potential role of oxidative stress in the clinical diagnosis of HCC.</p>
<p>In a further analysis, we found that PRDX1, among these six oxidative stress-related genes in the nomogram, was strongly associated with the prognosis of HCC and could contribute to judging the prognosis of HCC patients. Individuals with HCC who had high PRDX1 expression exhibited shorter overall survival, progression-free interval, and disease-specific survival time. Additionally, we found that PRDX1 was ubiquitously highly expressed in multiple liver cancer cell lines. PRDX1 is a multifunctional protein involved in cell proliferation, differentiation, and apoptosis that belongs to the peroxidase family and whose function in cancer is not well understood (<xref ref-type="bibr" rid="B61">Sun et al., 2022</xref>). It has been shown that overexpressed PRDX1 can activate toll-like receptor4, mTOR pathway, and TGF-&#x3b2;1 promotes tumor development and progression (<xref ref-type="bibr" rid="B49">Riddell et al., 2012</xref>). The single gene functional GSEA analysis of PRDX1 in HCC patients revealed a strong association between PRDX1 and the digestive system. PRDX1-related regulation of ribosome biogenesis, ncRNA processing, and snRNA processing was hyperactivated in HCC patients. In contrast, the PRDX1-associated IL-6-mediated signaling pathway, RNA gene silencing, and negative regulation of transporter activity were suppressed. Recent evidence (<xref ref-type="bibr" rid="B17">Elhamamsy et al., 2022</xref>) has revealed that ribosome biogenesis is a central process that promotes cell survival and stress-adaptive responses, collectively triggering tumor initiation and metastasis through ribosome modification. Cancer cells contain specialized oncogenic ribosomes that promote the translational program of oncogenes, regulate cellular functions and promote metabolic restructuring, increasing the risk of malignancy. Inferring low expression of PRDX1 may have an inhibitory effect on tumor progression.</p>
<p>For now, there are relatively few studies on the involvement of PRDX1 in the immunological microenvironment of HCC, which was analyzed by bioinformatics in our study. In the tumor microenvironment, HCC patients with low PRDX1 expression had more significant infiltration levels of M0 macrophages, M1 macrophages, CD4<sup>&#x2b;</sup> Th1 cells, CD4<sup>&#x2b;</sup> Th2 cells, myeloid dendritic cells, monocytes, and lymphoid progenitor cells. Whereas the endothelial cells and cancer associated fibroblasts were more abundant in the poor prognosis PRDX1 high expressing HCC patient population. Microsatellite instability, tumor mutational burden, and T cell exclusion are more pronounced in HCCs with high PRDX1 expression. Relevant immune functions APC co-inhibition, MHC class &#x2160;, and para-inflammation were more active in patients with high PRDX1 expression. Type &#x2161; INF response was more active in the low PRDX1 expression patient group. The expression levels of immune checkpoints (as PDCDL1G2, LAIR1, CTLA4, TIGIT) were positively correlated with the expression level of PRDX1. Our analysis of the potential role of PRDX1 in clinical therapeutic intervention revealed that HCC patients with high PRDX1 expression were susceptible to immunotherapy agents such as sorafenib, JAK inhibitor, IRAK4 inhibitor, and TGF-&#x3b2; Receptor I/II inhibitor, SKY inhibitor, and ERK inhibitor have a high degree of sensitivity. These findings indicated that PRDX1 is a prospective biomarker for predicting the prognosis and guiding treatment decisions for HCC.</p>
<p>However, this study relying on single-cell data from public databases have limitations that constraints on sample size and cell numbers and incomplete coverage of cell types and conditions. Therefore, the results may be affected by the inherent bias in case selection. Further large-scale prospective studies and <italic>in vivo</italic> and <italic>in vitro</italic> experiments were required.</p>
</sec>
<sec sec-type="conclusion" id="s5">
<title>5 Conclusion</title>
<p>In conclusion, our study unveiled variations in oxidative stress levels between non-tumor liver and HCC tissues. And we identified oxidative stress gene markers associated with hepatocarcinogenesis development, offering novel insights into the oxidative stress response mechanism in HCC.</p>
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<sec sec-type="data-availability" id="s6">
<title>Data availability statement</title>
<p>The original contributions presented in the study are included in the article/<xref ref-type="sec" rid="s11">Supplementary Material</xref>, further inquiries can be directed to the corresponding authors.</p>
</sec>
<sec id="s7">
<title>Author contributions</title>
<p>SqZ and XL collected and analyzed the data, wrote the manuscript. YZ and HH analyzed the data and reviewed the manuscript. SqZ, XL, JL, SjZ, and WK designed the study and revised the manuscript. All authors contributed to the article and approved the submitted version.</p>
</sec>
<sec id="s8">
<title>Funding</title>
<p>This study was supported by The National Natural Science Foundation of China (Nos 81903967, 82104647), Postdoctoral Science Foundation of China (No. 2021M700964), Discipline Construction Project of Guangdong Medical University (4SG23006G), and Guangdong Provincial Bureau of Traditional Chinese Medicine (20213011).</p>
</sec>
<sec sec-type="COI-statement" id="s9">
<title>Conflict of interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec sec-type="disclaimer" id="s10">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<sec id="s11">
<title>Supplementary material</title>
<p>The Supplementary Material for this article can be found online at: <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fcell.2023.1191074/full#supplementary-material">https://www.frontiersin.org/articles/10.3389/fcell.2023.1191074/full&#x23;supplementary-material</ext-link>
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<ref-list>
<title>References</title>
<ref id="B1">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Aboelella</surname>
<given-names>N. S.</given-names>
</name>
<name>
<surname>Brandle</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Kim</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Ding</surname>
<given-names>Z. C.</given-names>
</name>
<name>
<surname>Zhou</surname>
<given-names>G.</given-names>
</name>
</person-group> (<year>2021</year>). <article-title>Oxidative stress in the tumor microenvironment and its relevance to cancer immunotherapy</article-title>. <source>Cancers (Basel)</source> <volume>13</volume>, <fpage>986</fpage>. <pub-id pub-id-type="doi">10.3390/cancers13050986</pub-id>
</citation>
</ref>
<ref id="B2">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Agarwal</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Aponte-Mellado</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Premkumar</surname>
<given-names>B. J.</given-names>
</name>
<name>
<surname>Shaman</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Gupta</surname>
<given-names>S.</given-names>
</name>
</person-group> (<year>2012</year>). <article-title>The effects of oxidative stress on female reproduction: A review</article-title>. <source>Reprod. Biol. Endocrinol.</source> <volume>10</volume>, <fpage>49</fpage>. <pub-id pub-id-type="doi">10.1186/1477-7827-10-49</pub-id>
</citation>
</ref>
<ref id="B3">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Anderson</surname>
<given-names>N. M.</given-names>
</name>
<name>
<surname>Simon</surname>
<given-names>M. C.</given-names>
</name>
</person-group> (<year>2020</year>). <article-title>The tumor microenvironment</article-title>. <source>Curr. Biol.</source> <volume>30</volume>, <fpage>R921</fpage>&#x2013;<lpage>R5</lpage>. <pub-id pub-id-type="doi">10.1016/j.cub.2020.06.081</pub-id>
</citation>
</ref>
<ref id="B4">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Aran</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Hu</surname>
<given-names>Z.</given-names>
</name>
<name>
<surname>Butte</surname>
<given-names>A. J.</given-names>
</name>
</person-group> (<year>2017</year>). <article-title>xCell: digitally portraying the tissue cellular heterogeneity landscape</article-title>. <source>Genome Biol.</source> <volume>18</volume>, <fpage>220</fpage>. <pub-id pub-id-type="doi">10.1186/s13059-017-1349-1</pub-id>
</citation>
</ref>
<ref id="B5">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bae</surname>
<given-names>Y. S.</given-names>
</name>
<name>
<surname>Oh</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Rhee</surname>
<given-names>S. G.</given-names>
</name>
<name>
<surname>Yoo</surname>
<given-names>Y. D.</given-names>
</name>
</person-group> (<year>2011</year>). <article-title>Regulation of reactive oxygen species generation in cell signaling</article-title>. <source>Mol. Cells</source> <volume>32</volume>, <fpage>491</fpage>&#x2013;<lpage>509</lpage>. <pub-id pub-id-type="doi">10.1007/s10059-011-0276-3</pub-id>
</citation>
</ref>
<ref id="B6">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bai</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Tan</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>An</surname>
<given-names>Z.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>Y.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Quantitative estimation of intracellular oxidative stress in human tissues</article-title>. <source>Brief. Bioinform</source> <volume>23</volume>, <fpage>bbac206</fpage>. <pub-id pub-id-type="doi">10.1093/bib/bbac206</pub-id>
</citation>
</ref>
<ref id="B7">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bartsch</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Nair</surname>
<given-names>J.</given-names>
</name>
</person-group> (<year>2006</year>). <article-title>Chronic inflammation and oxidative stress in the genesis and perpetuation of cancer: role of lipid peroxidation, DNA damage, and repair</article-title>. <source>Langenbecks Arch. Surg.</source> <volume>391</volume>, <fpage>499</fpage>&#x2013;<lpage>510</lpage>. <pub-id pub-id-type="doi">10.1007/s00423-006-0073-1</pub-id>
</citation>
</ref>
<ref id="B8">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bernhagen</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Krohn</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Lue</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Gregory</surname>
<given-names>J. L.</given-names>
</name>
<name>
<surname>Zernecke</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Koenen</surname>
<given-names>R. R.</given-names>
</name>
<etal/>
</person-group> (<year>2007</year>). <article-title>MIF is a noncognate ligand of CXC chemokine receptors in inflammatory and atherogenic cell recruitment</article-title>. <source>Nat. Med.</source> <volume>13</volume>, <fpage>587</fpage>&#x2013;<lpage>596</lpage>. <pub-id pub-id-type="doi">10.1038/nm1567</pub-id>
</citation>
</ref>
<ref id="B9">
<citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname>Bucala</surname>
<given-names>R.</given-names>
</name>
</person-group> (<year>2012</year>). <source>The MIF handbook. Singapore</source>. <publisher-loc>Hackensack, NJ.</publisher-loc>: <publisher-name>World Scientific</publisher-name>.</citation>
</ref>
<ref id="B10">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Cerami</surname>
<given-names>E.</given-names>
</name>
<name>
<surname>Gao</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Dogrusoz</surname>
<given-names>U.</given-names>
</name>
<name>
<surname>Gross</surname>
<given-names>B. E.</given-names>
</name>
<name>
<surname>Sumer</surname>
<given-names>S. O.</given-names>
</name>
<name>
<surname>Aksoy</surname>
<given-names>B. A.</given-names>
</name>
<etal/>
</person-group> (<year>2012</year>). <article-title>The cBio cancer genomics portal: an open platform for exploring multidimensional cancer genomics data</article-title>. <source>Cancer Discov.</source> <volume>2</volume>, <fpage>401</fpage>&#x2013;<lpage>404</lpage>. <pub-id pub-id-type="doi">10.1158/2159-8290.CD-12-0095</pub-id>
</citation>
</ref>
<ref id="B11">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Chen</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Khodadoust</surname>
<given-names>M. S.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>C. L.</given-names>
</name>
<name>
<surname>Newman</surname>
<given-names>A. M.</given-names>
</name>
<name>
<surname>Alizadeh</surname>
<given-names>A. A.</given-names>
</name>
</person-group> (<year>2018</year>). <article-title>Profiling tumor infiltrating immune cells with CIBERSORT</article-title>. <source>Methods Mol. Biol.</source> <volume>1711</volume>, <fpage>243</fpage>&#x2013;<lpage>259</lpage>. <pub-id pub-id-type="doi">10.1007/978-1-4939-7493-1_12</pub-id>
</citation>
</ref>
<ref id="B12">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Cichoz-Lach</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Michalak</surname>
<given-names>A.</given-names>
</name>
</person-group> (<year>2014</year>). <article-title>Oxidative stress as a crucial factor in liver diseases</article-title>. <source>World J. Gastroenterol.</source> <volume>20</volume>, <fpage>8082</fpage>&#x2013;<lpage>8091</lpage>. <pub-id pub-id-type="doi">10.3748/wjg.v20.i25.8082</pub-id>
</citation>
</ref>
<ref id="B13">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Cowen</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Ideker</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Raphael</surname>
<given-names>B. J.</given-names>
</name>
<name>
<surname>Sharan</surname>
<given-names>R.</given-names>
</name>
</person-group> (<year>2017</year>). <article-title>Network propagation: A universal amplifier of genetic associations</article-title>. <source>Nat. Rev. Genet.</source> <volume>18</volume>, <fpage>551</fpage>&#x2013;<lpage>562</lpage>. <pub-id pub-id-type="doi">10.1038/nrg.2017.38</pub-id>
</citation>
</ref>
<ref id="B14">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Cruz</surname>
<given-names>J. A.</given-names>
</name>
<name>
<surname>Wishart</surname>
<given-names>D. S.</given-names>
</name>
</person-group> (<year>2007</year>). <article-title>Applications of machine learning in cancer prediction and prognosis</article-title>. <source>Cancer Inf.</source> <volume>2</volume>, <fpage>117693510600200</fpage>&#x2013;<lpage>117693510600277</lpage>. <pub-id pub-id-type="doi">10.1177/117693510600200030</pub-id>
</citation>
</ref>
<ref id="B15">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Dalle-Donne</surname>
<given-names>I.</given-names>
</name>
<name>
<surname>Rossi</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Colombo</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Giustarini</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Milzani</surname>
<given-names>A.</given-names>
</name>
</person-group> (<year>2006</year>). <article-title>Biomarkers of oxidative damage in human disease</article-title>. <source>Clin. Chem.</source> <volume>52</volume>, <fpage>601</fpage>&#x2013;<lpage>623</lpage>. <pub-id pub-id-type="doi">10.1373/clinchem.2005.061408</pub-id>
</citation>
</ref>
<ref id="B16">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>de Melo</surname>
<given-names>M. B.</given-names>
</name>
<name>
<surname>Daldegan-Bueno</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Menezes Oliveira</surname>
<given-names>M. G.</given-names>
</name>
<name>
<surname>de Souza</surname>
<given-names>A. L.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Beyond ANOVA and MANOVA for repeated measures: advantages of generalized estimated equations and generalized linear mixed models and its use in neuroscience research</article-title>. <source>Eur. J. Neurosci.</source> <volume>56</volume>, <fpage>6089</fpage>&#x2013;<lpage>6098</lpage>. <pub-id pub-id-type="doi">10.1111/ejn.15858</pub-id>
</citation>
</ref>
<ref id="B17">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Elhamamsy</surname>
<given-names>A. R.</given-names>
</name>
<name>
<surname>Metge</surname>
<given-names>B. J.</given-names>
</name>
<name>
<surname>Alsheikh</surname>
<given-names>H. A.</given-names>
</name>
<name>
<surname>Shevde</surname>
<given-names>L. A.</given-names>
</name>
<name>
<surname>Samant</surname>
<given-names>R. S.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Ribosome biogenesis: A central player in cancer metastasis and therapeutic resistance</article-title>. <source>Cancer Res.</source> <volume>82</volume>, <fpage>2344</fpage>&#x2013;<lpage>2353</lpage>. <pub-id pub-id-type="doi">10.1158/0008-5472.CAN-21-4087</pub-id>
</citation>
</ref>
<ref id="B18">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Forman</surname>
<given-names>H. J.</given-names>
</name>
<name>
<surname>Maiorino</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Ursini</surname>
<given-names>F.</given-names>
</name>
</person-group> (<year>2010</year>). <article-title>Signaling functions of reactive oxygen species</article-title>. <source>Biochemistry</source> <volume>49</volume>, <fpage>835</fpage>&#x2013;<lpage>842</lpage>. <pub-id pub-id-type="doi">10.1021/bi9020378</pub-id>
</citation>
</ref>
<ref id="B19">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Forman</surname>
<given-names>H. J.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>H.</given-names>
</name>
</person-group> (<year>2021</year>). <article-title>Targeting oxidative stress in disease: promise and limitations of antioxidant therapy</article-title>. <source>Nat. Rev. Drug Discov.</source> <volume>20</volume>, <fpage>689</fpage>&#x2013;<lpage>709</lpage>. <pub-id pub-id-type="doi">10.1038/s41573-021-00233-1</pub-id>
</citation>
</ref>
<ref id="B20">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ganesan</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Kulik</surname>
<given-names>L. M.</given-names>
</name>
</person-group> (<year>2023</year>). <article-title>Hepatocellular carcinoma: new developments</article-title>. <source>Clin. Liver Dis.</source> <volume>27</volume>, <fpage>85</fpage>&#x2013;<lpage>102</lpage>. <pub-id pub-id-type="doi">10.1016/j.cld.2022.08.004</pub-id>
</citation>
</ref>
<ref id="B21">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Gao</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Aksoy</surname>
<given-names>B. A.</given-names>
</name>
<name>
<surname>Dogrusoz</surname>
<given-names>U.</given-names>
</name>
<name>
<surname>Dresdner</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Gross</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Sumer</surname>
<given-names>S. O.</given-names>
</name>
<etal/>
</person-group> (<year>2013</year>). <article-title>Integrative analysis of complex cancer genomics and clinical profiles using the cBioPortal</article-title>. <source>Sci. Signal</source> <volume>6</volume>, <fpage>pl1</fpage>. <pub-id pub-id-type="doi">10.1126/scisignal.2004088</pub-id>
</citation>
</ref>
<ref id="B22">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Gupta</surname>
<given-names>R. K.</given-names>
</name>
<name>
<surname>Patel</surname>
<given-names>A. K.</given-names>
</name>
<name>
<surname>Shah</surname>
<given-names>N.</given-names>
</name>
<name>
<surname>Chaudhary</surname>
<given-names>A. K.</given-names>
</name>
<name>
<surname>Jha</surname>
<given-names>U. K.</given-names>
</name>
<name>
<surname>Yadav</surname>
<given-names>U. C.</given-names>
</name>
<etal/>
</person-group> (<year>2014</year>). <article-title>Oxidative stress and antioxidants in disease and cancer: A review</article-title>. <source>Asian Pac J. Cancer Prev.</source> <volume>15</volume>, <fpage>4405</fpage>&#x2013;<lpage>4409</lpage>. <pub-id pub-id-type="doi">10.7314/apjcp.2014.15.11.4405</pub-id>
</citation>
</ref>
<ref id="B23">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Gupta</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Pasupuleti</surname>
<given-names>V.</given-names>
</name>
<name>
<surname>Du</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Welford</surname>
<given-names>S. M.</given-names>
</name>
</person-group> (<year>2016</year>). <article-title>Macrophage migration inhibitory factor secretion is induced by ionizing radiation and oxidative stress in cancer cells</article-title>. <source>PLoS One</source> <volume>11</volume>, <fpage>e0146482</fpage>. <pub-id pub-id-type="doi">10.1371/journal.pone.0146482</pub-id>
</citation>
</ref>
<ref id="B24">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Halliwell</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Gutteridge</surname>
<given-names>J. M.</given-names>
</name>
</person-group> (<year>1986</year>). <article-title>Oxygen free radicals and iron in relation to biology and medicine: some problems and concepts</article-title>. <source>Arch. Biochem. Biophys.</source> <volume>246</volume>, <fpage>501</fpage>&#x2013;<lpage>514</lpage>. <pub-id pub-id-type="doi">10.1016/0003-9861(86)90305-x</pub-id>
</citation>
</ref>
<ref id="B25">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Hao</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Hao</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Andersen-Nissen</surname>
<given-names>E.</given-names>
</name>
<name>
<surname>Mauck</surname>
<given-names>W. M.</given-names>
<suffix>3rd</suffix>
</name>
<name>
<surname>Zheng</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Butler</surname>
<given-names>A.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>Integrated analysis of multimodal single-cell data</article-title>. <source>Cell</source> <volume>184</volume>, <fpage>3573</fpage>&#x2013;<lpage>3587.e29</lpage>. <pub-id pub-id-type="doi">10.1016/j.cell.2021.04.048</pub-id>
</citation>
</ref>
<ref id="B26">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Harrington</surname>
<given-names>J. S.</given-names>
</name>
<name>
<surname>Ryter</surname>
<given-names>S. W.</given-names>
</name>
<name>
<surname>Plataki</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Price</surname>
<given-names>D. R.</given-names>
</name>
<name>
<surname>Choi</surname>
<given-names>A. M. K.</given-names>
</name>
</person-group> (<year>2023</year>). <article-title>Mitochondria in health, disease, and aging</article-title>. <source>Physiol. Rev.</source> <volume>103</volume>, <fpage>2349</fpage>&#x2013;<lpage>2422</lpage>. <pub-id pub-id-type="doi">10.1152/physrev.00058.2021</pub-id>
</citation>
</ref>
<ref id="B27">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Heise</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Vetter-Kauczok</surname>
<given-names>C. S.</given-names>
</name>
<name>
<surname>Skazik</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Czaja</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Marquardt</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Lue</surname>
<given-names>H.</given-names>
</name>
<etal/>
</person-group> (<year>2012</year>). <article-title>Expression and function of macrophage migration inhibitory factor in the pathogenesis of UV-induced cutaneous nonmelanoma skin cancer</article-title>. <source>Photochem Photobiol.</source> <volume>88</volume>, <fpage>1157</fpage>&#x2013;<lpage>1164</lpage>. <pub-id pub-id-type="doi">10.1111/j.1751-1097.2012.01108.x</pub-id>
</citation>
</ref>
<ref id="B28">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Higgs</surname>
<given-names>M. R.</given-names>
</name>
<name>
<surname>Chouteau</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Lerat</surname>
<given-names>H.</given-names>
</name>
</person-group> (<year>2014</year>). <article-title>&#x27;Liver let die&#x27;: oxidative DNA damage and hepatotropic viruses</article-title>. <source>J. Gen. Virol.</source> <volume>95</volume>, <fpage>991</fpage>&#x2013;<lpage>1004</lpage>. <pub-id pub-id-type="doi">10.1099/vir.0.059485-0</pub-id>
</citation>
</ref>
<ref id="B29">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Hu</surname>
<given-names>Z.</given-names>
</name>
<name>
<surname>Teng</surname>
<given-names>X. L.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Yu</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Ding</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Yi</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>SENP3 senses oxidative stress to facilitate STING-dependent dendritic cell antitumor function</article-title>. <source>Mol. Cell</source> <volume>81</volume>, <fpage>940</fpage>&#x2013;<lpage>952.e5</lpage>. <pub-id pub-id-type="doi">10.1016/j.molcel.2020.12.024</pub-id>
</citation>
</ref>
<ref id="B30">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Huang</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Yuan</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Zhao</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Han</surname>
<given-names>Q.</given-names>
</name>
<name>
<surname>Yan</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Yuan</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2023</year>). <article-title>Gene signature developed for predicting early relapse and survival in early-stage pancreatic cancer</article-title>. <source>BJS Open</source> <volume>7</volume>, <fpage>zrad031</fpage>. <pub-id pub-id-type="doi">10.1093/bjsopen/zrad031</pub-id>
</citation>
</ref>
<ref id="B31">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Jin</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Guerrero-Juarez</surname>
<given-names>C. F.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Chang</surname>
<given-names>I.</given-names>
</name>
<name>
<surname>Ramos</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Kuan</surname>
<given-names>C. H.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>Inference and analysis of cell-cell communication using CellChat</article-title>. <source>Nat. Commun.</source> <volume>12</volume>, <fpage>1088</fpage>. <pub-id pub-id-type="doi">10.1038/s41467-021-21246-9</pub-id>
</citation>
</ref>
<ref id="B32">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Jin</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Nie</surname>
<given-names>Q.</given-names>
</name>
</person-group> (<year>2020</year>). <article-title>scAI: an unsupervised approach for the integrative analysis of parallel single-cell transcriptomic and epigenomic profiles</article-title>. <source>Genome Biol.</source> <volume>21</volume>, <fpage>25</fpage>. <pub-id pub-id-type="doi">10.1186/s13059-020-1932-8</pub-id>
</citation>
</ref>
<ref id="B33">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Kim</surname>
<given-names>E.</given-names>
</name>
<name>
<surname>Viatour</surname>
<given-names>P.</given-names>
</name>
</person-group> (<year>2020</year>). <article-title>Hepatocellular carcinoma: old friends and new tricks</article-title>. <source>Exp. Mol. Med.</source> <volume>52</volume>, <fpage>1898</fpage>&#x2013;<lpage>1907</lpage>. <pub-id pub-id-type="doi">10.1038/s12276-020-00527-1</pub-id>
</citation>
</ref>
<ref id="B34">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Leng</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Metz</surname>
<given-names>C. N.</given-names>
</name>
<name>
<surname>Fang</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Donnelly</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Baugh</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2003</year>). <article-title>MIF signal transduction initiated by binding to CD74</article-title>. <source>J. Exp. Med.</source> <volume>197</volume>, <fpage>1467</fpage>&#x2013;<lpage>1476</lpage>. <pub-id pub-id-type="doi">10.1084/jem.20030286</pub-id>
</citation>
</ref>
<ref id="B35">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Li</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>F.</given-names>
</name>
<name>
<surname>Niu</surname>
<given-names>Q.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Yu</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>P.</given-names>
</name>
<etal/>
</person-group> (<year>2023</year>). <article-title>A molecular classification of gastric cancer associated with distinct clinical outcomes and validated by an XGBoost-based prediction model</article-title>. <source>Mol. Ther. Nucleic Acids</source> <volume>31</volume>, <fpage>224</fpage>&#x2013;<lpage>240</lpage>. <pub-id pub-id-type="doi">10.1016/j.omtn.2022.12.014</pub-id>
</citation>
</ref>
<ref id="B36">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Li</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Fan</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Traugh</surname>
<given-names>N.</given-names>
</name>
<name>
<surname>Chen</surname>
<given-names>Q.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>J. S.</given-names>
</name>
<etal/>
</person-group> (<year>2017</year>). <article-title>Timer: A web server for comprehensive analysis of tumor-infiltrating immune cells</article-title>. <source>Cancer Res.</source> <volume>77</volume>, <fpage>e108</fpage>&#x2013;<lpage>e110</lpage>. <pub-id pub-id-type="doi">10.1158/0008-5472.CAN-17-0307</pub-id>
</citation>
</ref>
<ref id="B37">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Merk</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Mitchell</surname>
<given-names>R. A.</given-names>
</name>
<name>
<surname>Endres</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Bucala</surname>
<given-names>R.</given-names>
</name>
</person-group> (<year>2012</year>). <article-title>D-Dopachrome tautomerase (D-DT or MIF-2): doubling the MIF cytokine family</article-title>. <source>Cytokine</source> <volume>59</volume>, <fpage>10</fpage>&#x2013;<lpage>17</lpage>. <pub-id pub-id-type="doi">10.1016/j.cyto.2012.03.014</pub-id>
</citation>
</ref>
<ref id="B38">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Mitchell</surname>
<given-names>R. A.</given-names>
</name>
<name>
<surname>Yaddanapudi</surname>
<given-names>K.</given-names>
</name>
</person-group> (<year>2014</year>). <article-title>Stromal-dependent tumor promotion by MIF family members</article-title>. <source>Cell Signal</source> <volume>26</volume>, <fpage>2969</fpage>&#x2013;<lpage>2978</lpage>. <pub-id pub-id-type="doi">10.1016/j.cellsig.2014.09.012</pub-id>
</citation>
</ref>
<ref id="B39">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Mittal</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>El-Serag</surname>
<given-names>H. B.</given-names>
</name>
</person-group> (<year>2013</year>). <article-title>Epidemiology of hepatocellular carcinoma: consider the population</article-title>. <source>J. Clin. Gastroenterol.</source> <volume>47</volume>, <fpage>S2</fpage>&#x2013;<lpage>S6</lpage>. <pub-id pub-id-type="doi">10.1097/MCG.0b013e3182872f29</pub-id>
</citation>
</ref>
<ref id="B40">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Mootha</surname>
<given-names>V. K.</given-names>
</name>
<name>
<surname>Lindgren</surname>
<given-names>C. M.</given-names>
</name>
<name>
<surname>Eriksson</surname>
<given-names>K. F.</given-names>
</name>
<name>
<surname>Subramanian</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Sihag</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Lehar</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2003</year>). <article-title>PGC-1alpha-responsive genes involved in oxidative phosphorylation are coordinately downregulated in human diabetes</article-title>. <source>Nat. Genet.</source> <volume>34</volume>, <fpage>267</fpage>&#x2013;<lpage>273</lpage>. <pub-id pub-id-type="doi">10.1038/ng1180</pub-id>
</citation>
</ref>
<ref id="B41">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Nakamura</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Nakamura</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Yodoi</surname>
<given-names>J.</given-names>
</name>
</person-group> (<year>1997</year>). <article-title>Redox regulation of cellular activation</article-title>. <source>Annu. Rev. Immunol.</source> <volume>15</volume>, <fpage>351</fpage>&#x2013;<lpage>369</lpage>. <pub-id pub-id-type="doi">10.1146/annurev.immunol.15.1.351</pub-id>
</citation>
</ref>
<ref id="B42">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Nath</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Villadsen</surname>
<given-names>J.</given-names>
</name>
</person-group> (<year>2015</year>). <article-title>Oxidative phosphorylation revisited</article-title>. <source>Biotechnol. Bioeng.</source> <volume>112</volume>, <fpage>429</fpage>&#x2013;<lpage>437</lpage>. <pub-id pub-id-type="doi">10.1002/bit.25492</pub-id>
</citation>
</ref>
<ref id="B43">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Navarro-Yepes</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Burns</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Anandhan</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Khalimonchuk</surname>
<given-names>O.</given-names>
</name>
<name>
<surname>del Razo</surname>
<given-names>L. M.</given-names>
</name>
<name>
<surname>Quintanilla-Vega</surname>
<given-names>B.</given-names>
</name>
<etal/>
</person-group> (<year>2014</year>). <article-title>Oxidative stress, redox signaling, and autophagy: cell death versus survival</article-title>. <source>Antioxid. Redox Signal</source> <volume>21</volume>, <fpage>66</fpage>&#x2013;<lpage>85</lpage>. <pub-id pub-id-type="doi">10.1089/ars.2014.5837</pub-id>
</citation>
</ref>
<ref id="B44">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Osterman</surname>
<given-names>T. J.</given-names>
</name>
<name>
<surname>Terry</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Miller</surname>
<given-names>R. S.</given-names>
</name>
</person-group> (<year>2020</year>). <article-title>Improving cancer data interoperability: the promise of the minimal common oncology data elements (mCODE) initiative</article-title>. <source>JCO Clin. Cancer Inf.</source> <volume>4</volume>, <fpage>993</fpage>&#x2013;<lpage>1001</lpage>. <pub-id pub-id-type="doi">10.1200/CCI.20.00059</pub-id>
</citation>
</ref>
<ref id="B45">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Painuli</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Bhardwaj</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Kose</surname>
<given-names>U.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Recent advancement in cancer diagnosis using machine learning and deep learning techniques: A comprehensive review</article-title>. <source>Comput. Biol. Med.</source> <volume>146</volume>, <fpage>105580</fpage>. <pub-id pub-id-type="doi">10.1016/j.compbiomed.2022.105580</pub-id>
</citation>
</ref>
<ref id="B46">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Pasupuleti</surname>
<given-names>V.</given-names>
</name>
<name>
<surname>Du</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Gupta</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Yeh</surname>
<given-names>I. J.</given-names>
</name>
<name>
<surname>Montano</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Magi-Galuzzi</surname>
<given-names>C.</given-names>
</name>
<etal/>
</person-group> (<year>2014</year>). <article-title>Dysregulated D-dopachrome tautomerase, a hypoxia-inducible factor-dependent gene, cooperates with macrophage migration inhibitory factor in renal tumorigenesis</article-title>. <source>J. Biol. Chem.</source> <volume>289</volume>, <fpage>3713</fpage>&#x2013;<lpage>3723</lpage>. <pub-id pub-id-type="doi">10.1074/jbc.M113.500694</pub-id>
</citation>
</ref>
<ref id="B47">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Plattner</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Finotello</surname>
<given-names>F.</given-names>
</name>
<name>
<surname>Rieder</surname>
<given-names>D.</given-names>
</name>
</person-group> (<year>2020</year>). <article-title>Deconvoluting tumor-infiltrating immune cells from RNA-seq data using quanTIseq</article-title>. <source>Methods Enzym.</source> <volume>636</volume>, <fpage>261</fpage>&#x2013;<lpage>285</lpage>. <pub-id pub-id-type="doi">10.1016/bs.mie.2019.05.056</pub-id>
</citation>
</ref>
<ref id="B48">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Pouvreau</surname>
<given-names>S.</given-names>
</name>
</person-group> (<year>2014</year>). <article-title>Genetically encoded reactive oxygen species (ROS) and redox indicators</article-title>. <source>Biotechnol. J.</source> <volume>9</volume>, <fpage>282</fpage>&#x2013;<lpage>293</lpage>. <pub-id pub-id-type="doi">10.1002/biot.201300199</pub-id>
</citation>
</ref>
<ref id="B49">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Riddell</surname>
<given-names>J. R.</given-names>
</name>
<name>
<surname>Maier</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Sass</surname>
<given-names>S. N.</given-names>
</name>
<name>
<surname>Moser</surname>
<given-names>M. T.</given-names>
</name>
<name>
<surname>Foster</surname>
<given-names>B. A.</given-names>
</name>
<name>
<surname>Gollnick</surname>
<given-names>S. O.</given-names>
</name>
</person-group> (<year>2012</year>). <article-title>Peroxiredoxin 1 stimulates endothelial cell expression of VEGF via TLR4 dependent activation of HIF-1&#x3b1;</article-title>. <source>PLoS One</source> <volume>7</volume>, <fpage>e50394</fpage>. <pub-id pub-id-type="doi">10.1371/journal.pone.0050394</pub-id>
</citation>
</ref>
<ref id="B50">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Rigatti</surname>
<given-names>S. J.</given-names>
</name>
</person-group> (<year>2017</year>). <article-title>Random forest</article-title>. <source>J. Insur Med.</source> <volume>47</volume>, <fpage>31</fpage>&#x2013;<lpage>39</lpage>. <pub-id pub-id-type="doi">10.17849/insm-47-01-31-39.1</pub-id>
</citation>
</ref>
<ref id="B51">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Rigoulet</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Yoboue</surname>
<given-names>E. D.</given-names>
</name>
<name>
<surname>Devin</surname>
<given-names>A.</given-names>
</name>
</person-group> (<year>2011</year>). <article-title>Mitochondrial ROS generation and its regulation: mechanisms involved in H(2)O(2) signaling</article-title>. <source>Antioxid. Redox Signal</source> <volume>14</volume>, <fpage>459</fpage>&#x2013;<lpage>468</lpage>. <pub-id pub-id-type="doi">10.1089/ars.2010.3363</pub-id>
</citation>
</ref>
<ref id="B52">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ronen</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Akalin</surname>
<given-names>A.</given-names>
</name>
</person-group> (<year>2018</year>). <article-title>netSmooth: network-smoothing based imputation for single cell RNA-seq</article-title>. <source>F1000Res</source> <volume>7</volume>, <fpage>8</fpage>. <pub-id pub-id-type="doi">10.12688/f1000research.13511.3</pub-id>
</citation>
</ref>
<ref id="B53">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Rooney</surname>
<given-names>M. S.</given-names>
</name>
<name>
<surname>Shukla</surname>
<given-names>S. A.</given-names>
</name>
<name>
<surname>Wu</surname>
<given-names>C. J.</given-names>
</name>
<name>
<surname>Getz</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Hacohen</surname>
<given-names>N.</given-names>
</name>
</person-group> (<year>2015</year>). <article-title>Molecular and genetic properties of tumors associated with local immune cytolytic activity</article-title>. <source>Cell</source> <volume>160</volume>, <fpage>48</fpage>&#x2013;<lpage>61</lpage>. <pub-id pub-id-type="doi">10.1016/j.cell.2014.12.033</pub-id>
</citation>
</ref>
<ref id="B54">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Sakamoto</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Fujie</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Isomura</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Kaga</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Kohgo</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Yamada</surname>
<given-names>N.</given-names>
</name>
<etal/>
</person-group> (<year>2002</year>). <article-title>Secretion of macrophage migration inhibitory factor differs from interleukin-6 in hydrogen peroxide- and LPS-stimulated human fibroblasts</article-title>. <source>Int. Immunopharmacol.</source> <volume>2</volume>, <fpage>1123</fpage>&#x2013;<lpage>1131</lpage>. <pub-id pub-id-type="doi">10.1016/s1567-5769(02)00063-2</pub-id>
</citation>
</ref>
<ref id="B55">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Sasaki</surname>
<given-names>Y.</given-names>
</name>
</person-group> (<year>2006</year>). <article-title>Does oxidative stress participate in the development of hepatocellular carcinoma?</article-title> <source>J. Gastroenterol.</source> <volume>41</volume>, <fpage>1135</fpage>&#x2013;<lpage>1148</lpage>. <pub-id pub-id-type="doi">10.1007/s00535-006-1982-z</pub-id>
</citation>
</ref>
<ref id="B56">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Satapati</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Kucejova</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Duarte</surname>
<given-names>J. A.</given-names>
</name>
<name>
<surname>Fletcher</surname>
<given-names>J. A.</given-names>
</name>
<name>
<surname>Reynolds</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Sunny</surname>
<given-names>N. E.</given-names>
</name>
<etal/>
</person-group> (<year>2016</year>). <article-title>Mitochondrial metabolism mediates oxidative stress and inflammation in fatty liver</article-title>. <source>J. Clin. Investig.</source> <volume>126</volume>, <fpage>1605</fpage>. <pub-id pub-id-type="doi">10.1172/JCI86695</pub-id>
</citation>
</ref>
<ref id="B57">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Shi</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Leng</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Du</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Li</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2006</year>). <article-title>CD44 is the signaling component of the macrophage migration inhibitory factor-CD74 receptor complex</article-title>. <source>Immunity</source> <volume>25</volume>, <fpage>595</fpage>&#x2013;<lpage>606</lpage>. <pub-id pub-id-type="doi">10.1016/j.immuni.2006.08.020</pub-id>
</citation>
</ref>
<ref id="B58">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Simons</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Grieb</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Hristov</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Pallua</surname>
<given-names>N.</given-names>
</name>
<name>
<surname>Weber</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Bernhagen</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2011</year>). <article-title>Hypoxia-induced endothelial secretion of macrophage migration inhibitory factor and role in endothelial progenitor cell recruitment</article-title>. <source>J. Cell Mol. Med.</source> <volume>15</volume>, <fpage>668</fpage>&#x2013;<lpage>678</lpage>. <pub-id pub-id-type="doi">10.1111/j.1582-4934.2010.01041.x</pub-id>
</citation>
</ref>
<ref id="B59">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Simpson</surname>
<given-names>K. D.</given-names>
</name>
<name>
<surname>Templeton</surname>
<given-names>D. J.</given-names>
</name>
<name>
<surname>Cross</surname>
<given-names>J. V.</given-names>
</name>
</person-group> (<year>2012</year>). <article-title>Macrophage migration inhibitory factor promotes tumor growth and metastasis by inducing myeloid-derived suppressor cells in the tumor microenvironment</article-title>. <source>J. Immunol.</source> <volume>189</volume>, <fpage>5533</fpage>&#x2013;<lpage>5540</lpage>. <pub-id pub-id-type="doi">10.4049/jimmunol.1201161</pub-id>
</citation>
</ref>
<ref id="B60">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Su</surname>
<given-names>Z.</given-names>
</name>
<name>
<surname>Li</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Fu</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Wu</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Feng</surname>
<given-names>X.</given-names>
</name>
</person-group> (<year>2023</year>). <article-title>Improved prognostic prediction model for liver cancer based on biomarker data screened by combined methods</article-title>. <source>Math. Biosci. Eng.</source> <volume>20</volume>, <fpage>5316</fpage>&#x2013;<lpage>5332</lpage>. <pub-id pub-id-type="doi">10.3934/mbe.2023246</pub-id>
</citation>
</ref>
<ref id="B61">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Sun</surname>
<given-names>H. H.</given-names>
</name>
<name>
<surname>Li</surname>
<given-names>Y. L.</given-names>
</name>
<name>
<surname>Jiang</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Yin</surname>
<given-names>X. H.</given-names>
</name>
<name>
<surname>Jin</surname>
<given-names>X. L.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>PRDX1 influences the occurrence and progression of liver cancer by inhibiting mitochondrial apoptosis pathway</article-title>. <source>Cell J.</source> <volume>24</volume>, <fpage>657</fpage>&#x2013;<lpage>664</lpage>. <pub-id pub-id-type="doi">10.22074/cellj.2022.8159</pub-id>
</citation>
</ref>
<ref id="B62">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Szklarczyk</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Gable</surname>
<given-names>A. L.</given-names>
</name>
<name>
<surname>Lyon</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Junge</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Wyder</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Huerta-Cepas</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2019</year>). <article-title>STRING v11: protein-protein association networks with increased coverage, supporting functional discovery in genome-wide experimental datasets</article-title>. <source>Nucleic Acids Res.</source> <volume>47</volume>, <fpage>D607</fpage>&#x2013;<lpage>D13</lpage>. <pub-id pub-id-type="doi">10.1093/nar/gky1131</pub-id>
</citation>
</ref>
<ref id="B63">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Takahashi</surname>
<given-names>N.</given-names>
</name>
<name>
<surname>Nishihira</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Sato</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Kondo</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Ogawa</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Ohshima</surname>
<given-names>T.</given-names>
</name>
<etal/>
</person-group> (<year>1998</year>). <article-title>Involvement of macrophage migration inhibitory factor (MIF) in the mechanism of tumor cell growth</article-title>. <source>Mol. Med.</source> <volume>4</volume>, <fpage>707</fpage>&#x2013;<lpage>714</lpage>. <pub-id pub-id-type="doi">10.1007/bf03401765</pub-id>
</citation>
</ref>
<ref id="B64">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Takaki</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Yamamoto</surname>
<given-names>K.</given-names>
</name>
</person-group> (<year>2015</year>). <article-title>Control of oxidative stress in hepatocellular carcinoma: helpful or harmful?</article-title> <source>World J. Hepatol.</source> <volume>7</volume>, <fpage>968</fpage>&#x2013;<lpage>979</lpage>. <pub-id pub-id-type="doi">10.4254/wjh.v7.i7.968</pub-id>
</citation>
</ref>
<ref id="B65">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Tan</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Pu</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Zheng</surname>
<given-names>B.</given-names>
</name>
</person-group> (<year>2014</year>). <article-title>Optimization of breast mass classification using sequential forward floating selection (SFFS) and a support vector machine (SVM) model</article-title>. <source>Int. J. Comput. Assist. Radiol. Surg.</source> <volume>9</volume>, <fpage>1005</fpage>&#x2013;<lpage>1020</lpage>. <pub-id pub-id-type="doi">10.1007/s11548-014-0992-1</pub-id>
</citation>
</ref>
<ref id="B66">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Vogel</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Meyer</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Sapisochin</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Salem</surname>
<given-names>R.</given-names>
</name>
<name>
<surname>Saborowski</surname>
<given-names>A.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Hepatocellular carcinoma</article-title>. <source>Lancet</source> <volume>400</volume>, <fpage>1345</fpage>&#x2013;<lpage>1362</lpage>. <pub-id pub-id-type="doi">10.1016/S0140-6736(22)01200-4</pub-id>
</citation>
</ref>
<ref id="B67">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Wang</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Sebra</surname>
<given-names>R. P.</given-names>
</name>
<name>
<surname>Sfakianos</surname>
<given-names>J. P.</given-names>
</name>
<name>
<surname>Allette</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Yoo</surname>
<given-names>S.</given-names>
</name>
<etal/>
</person-group> (<year>2020</year>). <article-title>A reference profile-free deconvolution method to infer cancer cell-intrinsic subtypes and tumor-type-specific stromal profiles</article-title>. <source>Genome Med.</source> <volume>12</volume>, <fpage>24</fpage>. <pub-id pub-id-type="doi">10.1186/s13073-020-0720-0</pub-id>
</citation>
</ref>
<ref id="B68">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Wang</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Yu</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Qiu</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>X.</given-names>
</name>
<etal/>
</person-group> (<year>2023</year>). <article-title>A generalized non-linear model predicting efficacy of neoadjuvant therapy in HER2&#x2b; breast cancer</article-title>. <source>iScience</source> <volume>26</volume>, <fpage>106330</fpage>. <pub-id pub-id-type="doi">10.1016/j.isci.2023.106330</pub-id>
</citation>
</ref>
<ref id="B69">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Wirtz</surname>
<given-names>T. H.</given-names>
</name>
<name>
<surname>Saal</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Bergmann</surname>
<given-names>I.</given-names>
</name>
<name>
<surname>Fischer</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Heinrichs</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Brandt</surname>
<given-names>E. F.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>Macrophage migration inhibitory factor exerts pro-proliferative and anti-apoptotic effects via CD74 in murine hepatocellular carcinoma</article-title>. <source>Br. J. Pharmacol.</source> <volume>178</volume>, <fpage>4452</fpage>&#x2013;<lpage>4467</lpage>. <pub-id pub-id-type="doi">10.1111/bph.15622</pub-id>
</citation>
</ref>
<ref id="B70">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Wu</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Sedgwick</surname>
<given-names>A. C.</given-names>
</name>
<name>
<surname>Sun</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Bull</surname>
<given-names>S. D.</given-names>
</name>
<name>
<surname>He</surname>
<given-names>X. P.</given-names>
</name>
<name>
<surname>James</surname>
<given-names>T. D.</given-names>
</name>
</person-group> (<year>2019</year>). <article-title>Reaction-based fluorescent probes for the detection and imaging of reactive oxygen, nitrogen, and sulfur species</article-title>. <source>Acc. Chem. Res.</source> <volume>52</volume>, <fpage>2582</fpage>&#x2013;<lpage>2597</lpage>. <pub-id pub-id-type="doi">10.1021/acs.accounts.9b00302</pub-id>
</citation>
</ref>
<ref id="B71">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zaidieh</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Smith</surname>
<given-names>J. R.</given-names>
</name>
<name>
<surname>Ball</surname>
<given-names>K. E.</given-names>
</name>
<name>
<surname>An</surname>
<given-names>Q.</given-names>
</name>
</person-group> (<year>2019</year>). <article-title>ROS as a novel indicator to predict anticancer drug efficacy</article-title>. <source>BMC Cancer</source> <volume>19</volume>, <fpage>1224</fpage>. <pub-id pub-id-type="doi">10.1186/s12885-019-6438-y</pub-id>
</citation>
</ref>
<ref id="B72">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zhang</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Li</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Tang</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Kuang</surname>
<given-names>W.</given-names>
</name>
</person-group> (<year>2021a</year>). <article-title>Inflammation-related long non-coding RNA signature predicts the prognosis of gastric carcinoma</article-title>. <source>Front. Genet.</source> <volume>12</volume>, <fpage>736766</fpage>. <pub-id pub-id-type="doi">10.3389/fgene.2021.736766</pub-id>
</citation>
</ref>
<ref id="B73">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zhang</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Li</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Tang</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Kuang</surname>
<given-names>W.</given-names>
</name>
</person-group> (<year>2021b</year>). <article-title>The pyroptosis-related gene signature predicts the prognosis of hepatocellular carcinoma</article-title>. <source>Front. Mol. Biosci.</source> <volume>8</volume>, <fpage>781427</fpage>. <pub-id pub-id-type="doi">10.3389/fmolb.2021.781427</pub-id>
</citation>
</ref>
<ref id="B74">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zhang</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Zheng</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Li</surname>
<given-names>X.</given-names>
</name>
<name>
<surname>Hu</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Kuang</surname>
<given-names>W.</given-names>
</name>
</person-group> (<year>2023</year>). <article-title>Cellular senescence-related gene signature as a valuable predictor of prognosis in hepatocellular carcinoma</article-title>. <source>Aging (Albany NY)</source> <volume>15</volume>, <fpage>3064</fpage>&#x2013;<lpage>3093</lpage>. <pub-id pub-id-type="doi">10.18632/aging.204658</pub-id>
</citation>
</ref>
<ref id="B75">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zopluoglu</surname>
<given-names>C.</given-names>
</name>
</person-group> (<year>2019</year>). <article-title>Detecting examinees with item preknowledge in large-scale testing using extreme gradient boosting (XGBoost)</article-title>. <source>Educ. Psychol. Meas.</source> <volume>79</volume>, <fpage>931</fpage>&#x2013;<lpage>961</lpage>. <pub-id pub-id-type="doi">10.1177/0013164419839439</pub-id>
</citation>
</ref>
</ref-list>
</back>
</article>