Distinct adaptive strategies to cisplatin, vinblastine and gemcitabine in a panel of chemoresistant bladder cancer cell lines

Aim: Urinary bladder cancer (UBC) often develops chemoresistance, reducing treatment effectiveness. This study aimed to investigate diverse molecular mechanisms underlying acquired resistance by establishing and characterizing a comprehensive panel of UBC cell lines resistant to common chemotherapeutics. Methods: Fifteen UBC cell lines were examined: three parental lines (RT-112, TCC-SUP, UMUC-3) and twelve derived sublines adapted to cisplatin, vinblastine, or gemcitabine. Drug sensitivity was assessed using the SRB assay. Resistance mechanisms were explored via quantitative real-time PCR (targeting genes including ABCB1, dCK, hENT1, ECHDC1, TUBB3), Western blotting (assessing proteins such as p21, Cyclin B, and Mcl-1), and biochemical assessment of glutathione levels and redox state. Results: The adapted sublines exhibited distinct resistance profiles and cross-resistance patterns. Gene expression and protein analyses revealed drug- and lineage-specific alterations, involving factors such as p21, Cyclin B, and Mcl-1. Changes in glutathione metabolism were also associated with resistance. Notably, no single, universal mechanism accounted for resistance across the entire panel. Conclusion: UBC cells develop diverse, context-dependent adaptive strategies to resist cisplatin, vinblastine, and gemcitabine. These findings highlight the complexity of chemoresistance mechanisms. The characterized cell line panel represents a valuable resource for future studies aimed at understanding and overcoming drug resistance in bladder cancer, suggesting that personalized therapeutic approaches may be necessary.