Epigenetic silencing of miR-141 via core promoter methylation is associated with short-term bladder cancer...

Alterations in DNA methylation represent one of the earliest molecular events in bladder tumorigenesis and are strongly associated with treatment efficacy and prognosis. Herein, we investigated DNA methylation landscape of MIR141 promoter and elucidated its clinical relevance in bladder cancer (BlCa) patients. miRNA-seq was performed to analyze miRNA profile in bladder tumors. Expression analysis of miR-141-3p and methylation profiling of MIR141 promoter were performed in 15 patient-derived xenografts (PDXs) mouse models, and in our screening patients' cohort (n = 133). TCGA-BLCA (n = 412) was used as independent validation cohort. Survival analysis was performed employing tumor relapse/progression as clinical endpoints in non-muscle-invasive BlCa (NMIBC; TaT1), and mortality in muscle-invasive BlCa (MIBC; T2-T4) patients. Internal validation was conducted through bootstrap analysis, and the clinical benefit of the findings was evaluated using decision curve analysis. miRNA-seq highlighted miR-141-3p as one of the most significantly downregulated miRNAs in muscle-invasive and high-grade tumors, while PDXs, TCGA-BLCA and screening cohort revealed its robust epigenetic regulation through MIR141 core promoter methylation. Consistent with miR-141-3p loss, hypermethylation of MIR141 core promoter was associated with advanced stage and high-grade tumors, reduced survival in PDXs, and significantly higher risk of TaT1 patients for short-term progression to muscle-invasive disease. Multivariate models highlighted MIR141 promoter hypermethylation as independent predictor for NMIBC short-term progression, displaying superior clinical benefit in patients' prognostication. Overall, MIR141 core promoter methylation results in miR-141-3p loss in bladder tumors and correlates with patients' poor treatment outcome, offering improved risk-stratification and addressing prognostic heterogeneity beyond traditional markers.