Molecular mechanism of Smac gene enhancing the induction of chemotherapeutic drug on bladder cancer apoptosis

Objective To investigate the enhancing effect and molecular mechanism of Smac gene on the apoptosis induced by chemotherapeutic drug in the bladder cancer cell line T24. Methods The Smac gene was transfected into bladder cancer cell line T24 through the induction of liposome.The intrinsic Smac,XIAP,caspase 3 expression levels were detected by immunocytochemistry and RT PCR.The in vitro cellular growth activities were assayed by MTT colorimetry; the apoptosis rate was assayed by the flowcytometry. Results In comparison with the control cells, the apoptosis rate of T24 cells induced by mitomycin C was enhanced by transfected Smac gene.The apoptosis rates of T24 cells were 18.84% and 10.72% by treatment of 0.05 mg/ml and 0.005 mg/ml mitomycin C;while after Smac gene transfection the rates were 33.52%and 26.24%. There were significant differences between the transfected groups and the control groups ( P 10.05, P 20.01).Accordingly the level of XIAP was down regulated and caspase 3 was up regulated.The differences were significant ( P 0.05). Conclusions The Smac can inhibit IAPs,enhance caspase activity and the apoptosis rate of T24 cells induced by mitomycin C,which provides useful experimental evidence for bladder cancer therapy.