Cisplatin-induced cytotoxicity, apoptosis, and DNA damage were reduced in cisplatin-resistant urothelial carcinoma (UC) (T24/R) cells. (A) Parent T24 and cisplatin-resistant UC cell lines (T24/R) were treated with various concentrations of cisplatin (10–40 μM) for 24 h. Cell viability was assessed using the MTT assay. * p < 0.05 as compared T24/R cells with T24 cells. (B) Cells were exposed to cisplatin (20 μM) and DMSO for 24 h. Apoptotic cells were analyzed through FACS flow cytometry with propidium iodide and annexin V-FITC staining. Data are presented as means ± SD, * p < 0.05 as compared with T24/R. (C) Cell lysates were harvested, and the expression of a DNA damage marker (phospho-histone H2A.X, Ser139) was assessed using western blot analysis. All results shown are representative of at least three independent experiments.