The investigation of TRPM2 ion channel's role on autophagic pathways in human prostate cancer PC-3 cell line

Prostate cancer is one of the leading health problems among men in the world. Recently, it has been shown that also autophagic pathways are contribute to its ethiopathogenesis. Intracellular calcium levels described as key regulator of autophagy is regulated by calcium channels. TRPM2, a calcium channel, has function in oxidative stress mediated apoptosis. Although, it has been shown H2O2, one of reactive oxygen species, activates both TRPM2 and autophagy, it is not known whether TRPM2 has a role in oxidative stress-mediated autophagic pathways. In this study, it is aimed to investigate the role of TRPM2 on autophagic pathways in prostate cancer PC-3 cell line. In PC-3 cell line, H2O2 was applied for activation of apoptotic and autophagic pathways and TRPM2. TRPM2, autophagic and apoptotic activites were blocked through siRNA, 3-MA and z-VAD-fmk, respectively. mRNA expression profiles of genes related with TRPM2, autophagy and apoptosis was demonstrated by quantitative RT-PCR. AO-EB staining was performed to determine the autophagic activity. It was determined that H2O2 application led to decreased the cell viability and application of z-VAD-fmk+H2O2 caused more cell death compared to 3-MA+H2O2 application. It was detected that H2O2 application-induced cell death was slightly more than application of TRPM2-siRNA+H2O2. It was determined that the expressions of BAX and TP73 apoptotic genes were significantly increased the exposure to H2O2, TRPM2-siRNA+H2O2, 3-MA+H2O2, TRPM2-siRNA+3-MA+H2O2 applications compared to control. It was found that the exposure to z-VAD-fmk+H2O2 was increased expression of genes, involving in the autophagic process. It was detected that autophagic gene expressions in TRPM2-siRNA+z-VAD-fmk+H2O2 application were similar to the control. Our data suggest that, H2O2, generally, is activator for both autophagic and apoptotic pathways and performs this effect as the TRPM2 mediated. Furthermore it emphasizes that while TRPM2-siRNA application suppressing H2O2-induced autophagic pathways, activates apoptotic pathways. Consequently; in order to clarify the fully role of TRPM2 in the autophagic pathways, more detailed molecular genetic studies should be done.