AQP1 Suppresses Clear Cell Renal Cell Carcinoma via Epigenetic Silencing and TNF-Mediated Apoptosis

Clear cell renal cell carcinoma (ccRCC) is notorious for its clinical unpredictability. While Aquaporin-1 (AQP1) is a major water channel in healthy kidneys, its specific role and regulatory mechanisms in ccRCC remain unclear. Using bioinformatics analysis of 610 TCGA-KIRC patients (RNA sequencing and DNA methylation), single-cell transcriptomics of 27,402 cells, and experimental validation (CCK-8, scratch, Transwell, and xenograft assays, with Western blotting, HE staining, and immunohistochemistry), we systematically characterized AQP1 expression, regulation, and function. AQP1 was significantly downregulated in ccRCC via promoter hypermethylation, with single-cell analysis confirming tumor cell-specific loss. Low AQP1 correlated with worse prognosis; multivariate Cox regression identified AQP1 as an independent protective factor (HR = 0.510, p < 0.001), and a prognostic nomogram showed good predictive accuracy for 1-, 3-, and 5-year survival. AQP1 overexpression suppressed proliferation, migration, invasion, and xenograft growth, accompanied by upregulation of TNF-α, TNFRSF1A, Bax, and Cleaved Caspase-3 and reduced Vimentin, suggesting activation of TNF-related pro-apoptotic signaling. AQP1 is epigenetically silenced in ccRCC and suppresses tumor growth via TNF-mediated apoptosis, establishing it as an independent prognostic biomarker and candidate therapeutic target.