Bioinformatics analysis and experimental validation confirm COL6A3 as a promising target for renal cell carcinoma therapy.

Kidney cancer is a prevalent urogenital malignancy, with renal cell carcinoma (RCC) accounting for over 90% of cases. Despite the rising incidence and the primary use of surgery as a treatment, mortality rates remain high, highlighting an urgent need for effective therapeutic strategies. Collagen VI alpha 3 (COL6A3), an isoform of collagen VI, is known to play a key role in the pathogenesis of diabetes and obesity. However, its expression pattern, clinicopathological features, prognostic significance, and immune-related associations in RCC remain largely unexplored. Therefore, the aim of this study is to elucidate the biological function of COL6A3 in RCC, specifically exploring its role in the tumor immune microenvironment and the PI3K-AKT signaling pathway, to identify a novel therapeutic target. We investigated COL6A3 expression and associated clinical outcomes using online databases, including Tumor Immune Estimation Resource (TIMER), Gene Expression Profiling Interactive Analysis 2 (GEPIA2), and University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN), along with multiple R packages. Furthermore, tumor immune infiltration and immunotherapeutic responses, and chemotherapeutic sensitivities were computationally evaluated. Subsequently, biological functions were validated using Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), Cell Counting Kit-8 (CCK-8), colony formation, 5-ethynyl-2'-deoxyuridine (EdU), wound healing, and Transwell assays, and in vivo xenograft models. Our analysis revealed that COL6A3 expression was significantly upregulated in RCC tissues. High COL6A3 expression correlated with poor clinical prognosis and malignant progression. In vitro and in vivo experiments further demonstrated that COL6A3 promoted malignant behaviors, including proliferation and metastasis, in renal cancer cell lines by modulating the PI3K-AKT signaling pathway. Crucially, microenvironment profiling indicated that low COL6A3 expression was characterized by an enrichment of anti-tumor effector cells, specifically CD8+ T cells and activated natural killer (NK) cells. Predictive modeling further suggested that patients with elevated COL6A3 levels might exhibit reduced responsiveness to immune checkpoint inhibitors (ICIs). Conversely, these high-expressing tumors were predicted to be highly susceptible to specific targeted agents, notably tyrosine kinase and mTOR inhibitors. These findings indicate that COL6A3 acts as an oncogenic driver and a potential immunosuppressive indicator, serving as a novel prognostic biomarker and therapeutic target. This dual role offers new insights for stratifying patients and developing tailored immunotherapeutic and targeted therapies for renal cancer.