Bioinformatics Analysis Reveals Epigenetic Regulation of COL5A2 by Tumor-Suppressive miRNAs miR-101-3p and miR-29c-3p as a Potential Molecular Mechanism in Lung Adenocarcinoma

Background: Collagen type V alpha 2 (COL5A2) is an important regulator of tumor progression and metastasis in various tumors. microRNAs (miRNAs), key post-transcriptional regulators of gene expression, can act as tumor suppressors or oncogenes. Dysregulated miRNA is closely associated with tumor development and progression. This study aimed to investigate COL5A2 expression across different tumors and to investigate its prognostic, immune cell infiltration, and miRNA associations. Methods: We used the TIMER database to assess COL5A2 expression across various tumor types and tumor-infiltrating immune cells. The UALCAN database was used to study the associations between COL5A2 expression and tumor stages, while overall survival results were obtained using the Kaplan–Meier plotter. We identified tumor suppressor miRNAs predicted to regulate COL5A2 expression in different tumors using the miRNet database and evaluated correlations between their expression levels, COL5A2 expression, and patient survival using the StarBase database. Results: COL5A2 was significantly upregulated in 12 tumors, and the upregulated COL5A2 expression was associated with altered immune cell infiltration and worse overall survival in lung and stomach adenocarcinoma. A total of 29 tumor suppressor miRNAs were identified as potential regulators of COL5A2 expression. We found that hsa-miR-101-3p and hsa-miR-29c-3p were downregulated in lung adenocarcinoma and negatively correlated with COL5A2 expression, and their downregulated expression was associated with unfavorable prognosis. Conclusions: COL5A2 and its regulatory miRNAs, hsa-miR-101-3p and hsa-miR-29c-3p, may represent potential diagnostic and prognostic biomarkers and modulators of the tumor immune microenvironment in lung adenocarcinoma. These results warrant further experimental validation and future evaluation in the context of Sustainable Development Goal (SDG) 3-aligned cancer control strategies.