Targeting DNA Methyltransferases with a Pemetrexed–Mitomycin C Combination in Bladder Cancer

Objective: The goal of this study was to investigate the efficacy and underlying mechanisms of combined treatment with pemetrexed and mitomycin-C for metastatic bladder cancer. Pemetrexed reduces cancer cell proliferation by impairing DNA and RNA biosynthesis, whereas mitomycin-C induces cytotoxicity through disruption of DNA. Materials and Methods: The cytotoxic effects of the pemetrexed–mitomycin-C combination was evaluated in human bladder cancer cells (UM-UC-3) via Annexin V/PI-based flow cytometric analysis, followed by evaluation of DNMT1 mRNA and protein levels. Statistical analyses were performed using independent t-tests. Results: The combined treatment significantly induced apoptosis in bladder cancer cells at low concentrations, demonstrating a pronounced synergistic effect. Moreover, the combination markedly suppressed DNMT1 mRNA expression and protein levels, indicating inhibition of aberrant DNA methylation mechanisms associated with cancer progression. Conclusion: These results indicate that co-treatment with pemetrexed and mitomycin-C holds therapeutic potential in metastatic bladder cancer and may inform future efforts to design DNMT1-targeted inhibitory strategies.