Rottlerin-induced autophagy leads to apoptosis in bladder cancer cells

It has been well-established that apoptosis contributes to cancer cell death; however, the role of autophagy in cancer cell death remains unclear. The aim of the present study was to investigate the effects of rottlerin, a traditional Indian medicine, on cell growth inhibition and autophagy in EJ human bladder carcinoma cells in vitro. Cell viability, measured by MTT assay, was found to be suppressed in a dose- and time-dependent manner. In addition, apoptosis was significantly increased in cells treated with rottlerin, as indicated by increased annexin V-fluorescein isothiocyanate/propidium iodide staining and changes in the cell cycle distribution that indicated blockage at G1 phase. Rottlerin treatment also enhanced the activation of autophagy, with increased expression of microtubule-associated protein 1 light chain 3 (LC3)-II and the appearance of autophagosomes. The increased level of LC3-II and autophagosomes suggests that autophagy may contribute to apoptosis in these cells. In addition, no apparent alterations in the levels of pro-caspase-3, cleaved caspase-3, total poly (ADP ribose) polymerase (PARP) and cleaved-PARP were observed in cells treated with rottlerin, which indicates that caspases may not serve a key role during the process of apoptosis induced by rottlerin. Therefore, the results of the present study indicate that rottlerin promotes apoptosis and arrests the cell cycle in EJ cells, which may be caused by autophagy activation.