Effect of recombinant human programmed cell death 5 protein on cell apoptosis of human bladder cancer cell line BIU87 induced by cisplatin and its mechanism

Objective To observe the effect of recombinant human programmed cell death 5 (rhPDCD5) protein on the apoptosis of human bladder cancer cell line BIU87 induced by cisplatin(DDP) and to investigate its mechanism. Methods Inhibition rates of bladder cancer cell line BIU87 intervened by rhPDCD5 protein and/or DDP with different concentrations were tested by cell counting kit-8(CCK-8). The morphological changes of cells were detected by Hoechst 33342 staining.The cells apoptosis rates were examined by flow cytometry.The changes of expression of the cysteinyl aspartate specific proteinase-3 (Caspase-3)and B-cell lymphoma/Leukemia-2(bcl-2) were measured by Western blotting analysis. Results CCK-8 showed that rhPDCD5 protein or/and DDP could inhibit the proliferation of BIU87 cells effectively.Hoechst 33342 staining showed that the positive cells rate of cells treated with rhPDCD5 protein and DDP(31. 62±2. 33)% was obviously higher than that only treated with rhPDCD5 protein(9. 61± 0. 42)% or DDP(14. 12±0. 24)%, the difference was significant(F= 221. 42, P<0. 01).The flow cytometry(FCM)showed that the apoptosis rate of cells treated with rhPDCD5 protein and DDP(58. 74± 3. 48)% was obviously increased than that only treated with rhPDCD5 protein(18. 84±1. 23)% or DDP (21. 25±2. 27)%, the difference was significant(F= 228. 93, P<0. 01).Compared with the group only treated with rhPDCD5 protein or DDP, the expression of Caspase-3 of the group treated with rhPDCD5 protein and DDP was significantly up-regulated(F= 12. 60, P<0. 01)and the expression of bcl-2 was significantly down-regulated(F= 12. 20,P<0. 01). Conclusion rhPDCD5 protein can induce the apoptosis of BIU87 cells,and accelerate the apoptosis of BIU87 cells induced by DDP.rhPDCD5 protein may reduce the expression of bcl-2 protein and increase activation of Caspase-3 to play its role in promoting apoptosis. Key words: Programmed cell death 5; Cisplatin; Bladder neoplasm; Apoptosis