Celastrol induces caspase-dependent apoptosis of hepatocellular carcinoma cells by suppression of mammalian target of rapamycin.

Abstract

To investigate the efficacy of celastrol treatment of hepatocellular carcinoma (HCC) cells in vitro and in vivo and to propose a mechanism of action. A human HepG2 liver cancer cell line and a xenograft tumor model were used to investigate the effects of celastrol on HCC in vitro and in vivo. A CCK-8 kit was used to detect cell viability. Flow cytometry and terminal-deoxynucleoitidyl transferase mediated nick end labeling staining were used to detect apoptosis. Western blotting and immunohistochemistry were used to detect the expression of cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9, cleaved-PARP, mammalian target of rapamycin (mTOR), and p-mTOR. Hematoxylin-eosin staining was used to observe the tissue morphology. Celastrol decreased the viability of HepG2 cells and induced apoptosis. Western blot assays indicated that celastrol up-regulated cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9, and cleaved-PARP by inhibiting the phosphorylation of mTOR in HepG2 cells. Moreover, celastrol inhibited the tumor growth in a xenograft model. Celastrol also induced caspase-dependent apoptosis (up-regulation of cleaved-caspase- 3, -8, -9, and cleaved-PARP) and inhibited the activation of mTOR in vivo. Celastrol induces caspase-dependent apoptosis in HCC cells by inhibiting the activation of mTOR.