Decoding the Role of Macrophage LAP3 in Lung Cancer – Integration of Single-Cell Technologies and Machine Learning Reveals an Orchestrating Immunometabolic Circuit at the Tumor-Epithelial Interface

yunlong dong¹Zhibin Fei¹Xuanguang Li²Hongsheng Guo³Wencheng Zhang¹Hongjie Zhao^1*Mengmeng Jiang^3*Xu Chang^4*Guangshun Wang^1*

• ¹天津市宝坻区人民医院, 天津市, China
• ²Tianjin Medical University General Hospital, Tianjin, China
• ³Tianjin University Central Hospital, Tianjin, China
• ⁴Shandong First Medical University Cancer Hospital, Jinan, China

.Background: Amino acid metabolism plays a crucial role in shaping tumor–immune crosstalk in non–small cell lung cancer (NSCLC). However, the key cellular mediators that translate metabolic states into intercellular signals remain poorly defined. Methods: We integrated single-cell RNA-seq with spatial transcriptomics to map immunometabolic architecture. Transcriptional co-variation was decomposed into amino-acid metabolic programs using Nonnegative Matrix Factorization (NMF); spatial deconvolution localized programs and cell types in tissue. Myeloid populations were subclustered to resolve macrophage states. Functional assays tested LAP3 overexpression (OE-LAP3) in A549/PC9 cells (qRT-PCR, Western blot, CCK-8, colony formation, wound-healing, Transwell) and a nude-mouse subcutaneous mouse model. Results: Integrative single-cell and spatial transcriptomic analyses revealed that tumor epithelial and myeloid cells dominate the NSCLC microenvironment and exhibit lineage-specific activation of amino acid metabolic programs. Notably, LAP3 was selectively enriched in both tumor epithelium and a distinct macrophage subset. Spatial mapping localized this LAP3-high macrophage state to epithelial–myeloid interfaces, where it functions as a signaling hub, actively secreting chemokines, cytokines, adhesion molecules, and extracellular matrix (ECM) components.To test whether LAP3 plays a causal role in tumor behavior, we established stable LAP3-overexpressing A549 and PC9 cell lines, confirming robust upregulation at both mRNA and protein levels. Functionally, LAP3 overexpression significantly suppressed proliferation—evident in CCK-8 time-course and colony formation assays—and impaired motility and invasiveness, as shown by delayed wound healing and reduced cell migration/invasion in Transwell assays. Most importantly, these effects translated in vivo: LAP3-overexpressing xenografts formed markedly smaller tumors in nude mice. Conclusions:LAP3 appears to functionally link amino acid catabolism to immune communication in NSCLC, defining an epithelial–macrophage immunometabolic niche where metabolic activity may shape the immune contexture. Its overexpression is associated with attenuated malignant phenotypes and heightened immune engagement, suggesting a potential dual role in restraining tumor aggressiveness and fostering an immune-responsive microenvironment. While these findings support LAP3 as a candidate biomarker for patient stratification and provide a rationale for combining metabolic modulation with immunotherapy, further mechanistic and clinical validation remains necessary.