ABT-737, a Bcl-2 family inhibitor, has a synergistic effect with apoptosis by inducing urothelial carcinoma cell necroptosis

ABT-737 is a recently reported inhibitor of members of the Bcl-2 family of apoptosis regulators. However, to the best of our knowledge, its necroptosis-inducing function in bladder cancer has not yet been researched. Thus, the present study aimed to investigate whether this Bcl-2 family inhibitor can induce both apoptosis and necroptosis of urothelial carcinoma cells. The proliferation and survival of urothelial carcinoma cell lines treated with a combination of both Z-VAD-FMK as a pan-caspase inhibitor and ABT-737 were assessed in vitro. Z-DNA binding protein 1 (ZBP1), receptor-interacting protein (RIP)1 and RIP3 were knocked down using small interfering RNA in urothelial carcinoma cell lines. The protein expression levels of ZBP1, RIP1 and RIP3 following cell transfection were measured via western blot analysis. Cell viability was determined using an MTT assay. Cell invasion was examined using cell invasion assays. The expression levels of necroptosis-related proteins, high mobility group box 1, ZBP1, mixed-lineage kinase domain-like protein (MLKL) and RIP3, were measured via western blotting. It was found that ABT-737 inhibited the proliferation and invasion of bladder cancer cells by inducing cell necrosis. The data demonstrated that ZBP1 and RIP3 have main roles in the cell necrosis induced by ABT-737. In addition, RIP3 and ZBP1, without interacting with RIP1, directly induced MLKL-mediated programmed cell necrosis. Thus, understanding how urothelial carcinoma cells react to Bcl-2 family inhibitors may accelerate the discovery of drugs to treat bladder cancer.