The cytotoxic effect,cell cycle perturbations and apoptosis by gemcitabine in human bladder cancer lines

Background and purpose:Gemcitabine is effective as single-agent in the treatment of bladder cancer,but the mechanisms for the induction of apoptosis by gemcitabine is not clear.This study was aimed at determining the molecular mechanisms and the efficacy of gemcitabine.Methods:BIU-87,5637,T24 and EJ bladder cancer cell lines were cultured.The cytotoxic activity and apoptosis were analyzed by MTT and Annexin-V assay as well as DNA cytometry,respectively.The effects on the cell cycle were assessed by flow cytometry of propidium iodide.The expressions of genes of bcl-2,bax,p53 and Caspase3 were determined by flow cytometry immunofluorescence.Results:Gemcitabine inhibited cell proliferation in dose dependent manner.G_(2)/M arrest(83.94% and 85.46%) could be observed,especially obvious 5637 and EJ cell lines,after cell incubation with gemcitabine.The apoptosis percentages were 4.8%,11.7%,23.3% 12 hr,24 hr and 48 hr after 5637 cells exposure to 1μg/ml gemcitabine.The expressions of p53 and bcl-2 were not influenced,whereas the expressions of bax and Caspase3 were increased in a time-dependent manner after cells exposure to gemcitabine.The Annexin-V positive cells were significantly increased in dose-dependent way.Conclusions:Gemcitabine could inhibit cell proliferation,especially bladder cancer cells with the phenotype of low grade and shorter doubling time.Gemcitabine could arrest cells at G2/M phase and induce apoptosis possibly through the pathway of bcl-2/bax in bladder cancer cell lines.