Long non-coding RNAs and JAK/STAT signaling pathway regulation in colorectal cancer development

Colorectal cancer (CRC) is one of the main fatal cancers. Cell signaling such as Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling substantially influences the process of gene expression and cell growth. Long non-coding RNAs (lncRNAs) play regulatory roles in cell signaling, cell proliferation, and cancer fate. Hence, lncRNAs can be considered biomarkers in cancers. The inhibitory or activating effects of different lncRNAs on the JAK/STAT pathway regulate cancer cell proliferation or tumor suppression. Additionally, lncRNAs regulate immune responses which play a role in immunotherapy. Mechanisms of lncRNAs in CRC via JAK/STAT regulation mainly include cell proliferation, invasion, metastasis, apoptosis, adhesion, and control of inflammation. More profound findings are warranted to specifically target the lncRNAs in terms of activation or suppression in hindering CRC cell proliferation. Here, to understand the lncRNA cross-talk in CRC through the JAK/STAT signaling pathway, we collected the related in vitro and in vivo data. Future insights may pave the way for the development of novel diagnostic tools, therapeutic interventions, and personalized treatment strategies for CRC patients.


JAK/STAT and colorectal cancer
The sensing, cytokine receptor binding, and phosphorylation of the JAK/STAT pathway lead to related gene regulation.The activation of STATs results in the transcriptional regulation of immune responses, apoptosis, inflammation, proliferation, and angiogenesis.Genetic mutations in the JAK-STAT pathway lead to aberrant activation, even without the cytokine induction, which results in persistent activation and tumorigenesis.For instance, persistent overexpression of STAT5 occurs in the neoplasia stage.It was revealed that circular RNA circSPARC promotes the invasion of CRC cells via JAK/STAT pathway regulation (Wang J. et al., 2021).A previous study showed that activating transcription factor 1 (ATF1) was associated with CRC progression via regulating the JAK/STAT, TNF, and Wnt pathways.ATF1 was also associated with the two lncRNAs PVT1 and CCAT1, which played a role in the exacerbation of CRC (Wang H. et al., 2021).CCAT5 also upregulates STAT3 in CRC (Wang et al., 2020).The ADAM10-JAK-STAT signaling pathway can also be regulated by miR-365a-3p, thus inhibiting CRC cell proliferation (Hong et al., 2020).STAT3 also mediates the activation and infiltration of tumor-specific T cells.A bibliometric analysis deciphered a myriad of lncRNAs associated with CRC progression, invasion, and metastasis (He and Wu, 2023).The downregulation of STAT3 by miR-34a inhibits CRC cell metastasis.In addition, interactions between CASC2, miR-18a, PIAS3 (an mRNA molecule), and the STAT3 signaling pathway caused CRC cell multiplication and tumor development (Huang et al., 2016a).
Low immune response and immune evasion lead to cancer cell multiplication, invasion, and metastasis.Although various lncRNAs (such as Neat1 and RUNX3) (Pandey et al., 2022) have participated in immunosuppression in cancers, some of them have exhibited immunostimulatory properties (Eptaminitaki et al., 2021).lncRNAs are of significance in the multiplication and activation of CD4 + and CD8 + T cells and NK cells (Li et al., 2021).MHC-I and immunogenicity of tumor (LIMIT) is an lncRNA, which provokes the expression of the MHC-I gene via detachment of heat shock factor-1 (HSF1) and HSP90 proteins.RNA-guided CRISPR activation results in MHC-I overexpression, T-cell recruitment, and checkpoint blockade response (Li et al., 2021).lncRNA AFAP1-AS1 increases PD-1 molecule expression in nasopharyngeal carcinoma (Tang et al., 2017).lncRNA Olfr29-ps1 targets miR-214-3p, which decreases MDSC activity and differentiation mediated by MyD88 (Shang et al., 2019).lncRNA RP11705C15 provokes efficient immune responses against NSCLC cells following anti PD-1 immunotherapy (Xu et al., 2018).lncRNA MIR-155HG is also associated with the overall survival (OS) of patients suffering from various cancers (Li et al., 2016).lncRNA Flicr impairs the Treg functions and, hence, enhances the immune responses.CD8 + T-cell activation is mediated by NKILA, Morrbid, and GM16343.In addition, MM2P enhances macrophage activation.HOTAIRM1 and MALAT1 preclude MDSC-mediated immunosuppression.GAS5, RP11-222K-16.2,IFNG-AS1, and lnc-CD56 enhance NK cell activity.In hepatocellular carcinoma, FENDRR hinders the activity and multiplication of Tregs.lnc-BM regulates macrophage recruitment into the brain and HCC TME.In NSCLC, linc EPHA6-1 enhances NK cell cytotoxicity.In lung adenocarcinoma, NKX2-1-AS1 inhibits PDL-1 expression.Furthermore, lncRNAs GAS5 and RP11-291B-21.2enhance the responses to trastuzumab and durvalumab, respectively.An in silico study demonstrated that high expression levels of two lncRNAs SNHG1 and SNHG7 (using GEO analysis and GSEA) in HCC tissue were associated with the expression of various immunerelated genes.These genes were mainly related to infiltration and checkpoint inhibitors (Chen E. et al., 2022).The combination of locked nucleic acid (LNA)-ASOs and LINK-A lncRNA has suppressed breast cancer progression (Hu Q. et al., 2019).Moreover, the incorporation of lncRNA into CAR T cells has played the role of an adjuvant in the regulation of T-cell apoptosis and suppressed tumor immune evasion and enhanced the immunotherapy (Huang et al., 2018).

JAK/STAT pathway targeting in immunotherapies
The enhanced expression of cytokines and their receptors mainly result in the aberrant regulation of JAK1/2, STAT1, STAT3, STAT5, and STAT6, causing inflammation and cancer development, cancer recurrence, and decreased overall survival.JAK1 and STAT3 are necessary for T-cell activation.Hence, the impairment in the system affects efficient cancer cell combating and even leads to T-cell lymphoma (Waldmann and Chen, 2017).INF-JAK/STAT pathway targeting can provide efficient outcomes in immunotherapy and radiotherapy, considering sufficient strength and duration of treatment.JAK1 signaling has participated in PDL-1-mediated melanoma immunotherapy (Luo et al., 2018;Shi and Bonner, 2021).Moreover, JAK/STAT targeting, particularly of combination therapy, is promising for glioblastoma treatment (Ou A. et al., 2021;Shi and Bonner, 2021).STAT3 activation suppresses immune cells and targets interleukin-6 (IL-6), which activates MDSCs and shifts Th1/Th2 balance to Th2 type.Therefore, JAK/STAT inhibitors are promising for cancer therapy (Sabaawy and Zeeshan, 2021).The suppression of STAT5, an activator of CD4+/CD25+ Tregs, can activate immune cells such as NK cells (Gotthardt et al., 2016).Targeting JAK/STAT signals leads to the inhibition of chronic inflammation, anti-tumor cell suppression, and more effective cancer therapy (Sabaawy et al., 2021).The human microbiota may affect the expression of lncRNAs, such as HOTAIR, LINC00491, KCNQ1OT1, and LINC00355, by CRC cells (Yang et al., 2020;Khodaii et al., 2022).RPS6, PMAIP1, BCL2, and FAM129A genes were associated with immune cell infiltration (Tan et al., 2021).
LINC00691 has regulated the JAK/STAT pathway and led to gastric cancer cell proliferation and invasion, which was confirmed using MKN-45 and HGC-27 cell lines and bioinformatics study, gene expression, luciferase gene reporter, Western blot, and in vivo (BALB/c nude mice) analyses (Liang et al., 2020).The inhibitor ruxolitinib could reverse the LINC00691 effects.

Long non-coding RNAs and JAK/STAT regulation in colorectal cancer
It was observed that lncRNA RP11-468E2.5 exerted anticancer effects against CRC via apoptosis induction and precluding angiogenesis in silico, in vitro (tissue samples from 169 patients), and in vivo.lncRNA RP11-468E2.5 targeted the JAK/STAT signaling pathway via inhibition of STAT5 and STAT6.RP11-468E2.5 targeting using siRNA reversed the effects and inhibited apoptosis.Moreover, lncRNA LINC01116 has accelerated CRC progression via regulation of miR-9-5p/STMN1 and interleukin-6 receptor (IL-6R) (Bi et al., 2020b).LINC01116 exhibited a high expression level in CRC tissues, and its knockdown could hinder cancer progression.LINC01116 has also promoted cancer cell proliferation and migration (Xu et al., 2021).On the other hand, lncRNA AB073614 has exerted mesenchymal CRC cell tumorigenesis via JAK/STAT3 pathway regulation.It was highly expressed in CRC tissue, and its suppression in SW480 and HCT116 cells hindered the cell proliferation and invasion via expression of E-cadherin and occludin proteins.The phosphorylated STAT3 expression was also mitigated.lncRNA AB073614 has also decreased tumor growth, invasion, and metastasis; cell cycle arrest; and promotion of apoptosis.Other roles included regulation of EMT and Wnt-β catenin pathway (Liao et al., 2019;Liao et al., 2021;Yang et al., 2021).
lncRNA LINC00346 has been associated with CRC cell proliferation and invasion, Bcl-2 increase, and caspase-3 and Bax downregulation in HT29 and LoVo CRC cells.Its silencing was associated with apoptosis induction and inhibition of cancer progression via inhibiting the JAK/STAT signaling pathway.Interestingly, tofacitinib (JAK1 inhibitor) could reverse its cancer-promoting effects (Li and Wen, 2020).Moreover, triptolide, an inhibitor of JAK1 and phosphorylated STAT3, hindered the proliferation of CRC cells (Wang et al., 2009).Zhang L. et al. (2021) assessed 72 CRC and 36 adjacent normal tissues and revealed that lncRNA TPT1-AS1 facilitates CRC progression and metastasis through upregulation of JAK/ STAT3 and FAK pathways by the expression of tumor protein translationally controlled 1 (TPT1).Additionally, in vivo findings revealed CRC cell proliferation by clone formation and tumor size/weight assay in nude mice.Chen et al. (2020)showed that the HOXA11-AS/miR-149-3p axis caused CRC cell proliferation and HCT116 cell migration.They also demonstrated that, with HOXA11-AS being its molecular sponge, miR-149-3p could lead to increased E-cadherin expression (Table 1; Figure 3).HOTAIR is another lncRNA overexpressed in CRC and promotes tumor growth and metastasis.HOTAIR interacts with the JAK-STAT pathway by binding to STAT3, leading to its activation and subsequent promotion of CRC cell proliferation and invasion (Liu et al., 2019).UCA1 is upregulated in CRC and activates the JAK-STAT pathway.UCA1 promotes CRC cell proliferation, migration, and invasion by enhancing STAT3 phosphorylation and nuclear translocation (Liu et al., 2021).GAS5 is downregulated in CRC and acts as a tumor suppressor.GAS5 inhibits the JAK-STAT pathway by interacting with JAK2 and preventing its phosphorylation.This leads to decreased STAT3 activation and suppression of CRC cell growth and invasion (Lin et al., 2022;Shakhpazyan et al., 2023).
MALAT1 is upregulated in CRC and has been implicated in promoting tumor growth and metastasis.MALAT1 activates the JAK-STAT pathway by interacting with STAT3 and enhancing its phosphorylation, thereby contributing to CRC progression.

Future prospects
In recent years, there has been a growing body of research that has shed light on the significant contribution of non-coding RNAs to the pathogenesis of different types of cancers (Wu J. et al., 2022;Gao et al., 2022;Liu et al., 2023;Xie et al., 2023).Specifically, lncRNAs and the JAK-STAT pathway have emerged as pivotal factors in the initiation and advancement of CRC (Li B. et al., 2022).The understanding of the biological functions and mechanisms of lncRNAs in cancer is essential for future studies to succeed in early diagnosis (as biomarkers) and achievement of appropriate therapeutic options (Dai et al., 2017;Xie et al., 2022).RNA sequencing revealed several lncRNAs as CRC biomarkers including CRCAL-1-4 (Yamada et al., 2018).The traits and pathophysiology of various cancers have been related to lncRNAs which can be considered "genetic debris" prognostic or diagnostic biomarkers.Their specific therapy is possible considering tissue-specific expression.Discovering lncRNA cross-talk and its effects on CRC progression is also helpful in understanding regulatory mechanisms.Consequently, these verification aspects contribute to the guide of inhibitory or activating drugs/compounds.As the detection of lncRNA expression is convenient in patients' samples, they can be considered biomarkers of diagnosis or prognosis of cancers/ disease type.The minimal side effects due to the lncRNA targeting in cancers (for oncogenic circuit blocking), lncRNAbased cancer therapy such as restricted expression is promising.Cancer-suppressing lncRNA expression can be enhanced using various approaches such as nanovectors.The knockout of lncRNAs using CRISPR-CAS9 is another approach for cancer therapy, which has reduced metastasis and increased the survival rate of mice (Zhuo et al., 2019).Targeting of the JAK/ STAT pathway can lead to the activation of anti-tumor immune cells, and combination therapies are promising in this regard (Sabaawy et al., 2021).In addition, functional characterization of lncRNAs, identification of lncRNA biomarkers, therapeutic targeting of lncRNAs, elucidating the cross-talk between lncRNAs and the JAK-STAT pathway, and integration of lncRNAs and the JAK-STAT pathway into personalized medicine open new avenues in future.

Conclusion
lncRNAs play substantial roles in the regulation of cancerdriving pathways, and their roles have been recently demonstrated in the field of oncology.lncRNAs can be considered for cancer theranostic aims.By unveiling the biological roles of lncRNAs in the regulation of epithelial cell proliferation and mechanisms of development to neoplasia and more, cancer diagnosis will face a promising future when lncRNA radiotracing technology comes to clinical use.The understanding of lncRNA interactions or their cross-talk is also important for efficient precluding of cancer development.Several lncRNAs play a role as oncogenic or tumor-suppressor agents via regulation of JAK/STAT signaling.Hence, the targeting of this pathway is crucial for efficacious CRC anti-tumor therapy.

FIGURE 1
FIGURE 1 lncRNA expression changes in cancers.

FIGURE 2
FIGURE 2Mechanisms of lncRNAs in cellular pathway regulation in cancers.
TABLE1 lncRNA level changes and their mechanisms in CRC conditions.