The prosurvival role of autophagy in resveratrol-induced cytotoxicity in GH3 cells

: In a previous study, we reported that resveratrol exerts antitumor effects through the estrogen receptor in prolactinoma. The autophagy/lysosomal degradation pathway plays an important role in damage control and energy efficiency. In this study, we investigated the involvement of autophagy and the related signaling pathways in resveratrol-induced apoptosis of GH3 cells. We demonstrate that resveratrol inhibits cell proliferation and induces apoptosis in a dose-dependent manner in GH3 cells. The cleavage of PARP was also observed, and the activation of caspase-3 and caspase-8 was detected. Consistent with this finding, the inhibition of caspase activation effectively attenuated resveratrol-induced cell apoptosis. In addition, the decreased level of Bcl-2 was also observed. The induction of autophagy was confirmed by the detection of the formation of autophagic vacuoles, and the increase in microtubule-associated protein 1 light chain 3 (LC3)-II and beclin-1 levels, two hallmarks of autophagy. Pre-treatment with bafilomycin A1 or 3-methyladenine, inhibitors of autophagy, enhanced the resveratrol-mediated caspase activation and cell death. Moreover, resveratrol induced the activation of ERK1/2, as well as the downregulation of Akt and mTOR phosphorylation. Taken together, these findings indicate that resveratrol induces caspase-dependent apoptosis and decreases Bcl-2 levels. In addition, resveratrol-induced autophagy is regulated by the PI3K/Akt/mTOR and ERK1/2 pathways. Furthermore, the inhibition of autophagy increases the cytotoxicity of resveratrol to GH3 cells.