Abstract: OBJECTIVE:To investigate the apoptotic effects and underlying molecular mechanisms of Celastrus orbiculatus(C.orbiculatus) extract in human hepatocellular carcinoma cells.METHODS:Human hepatocellular carcinoma cells(HCCLM6) were treated with C.orbiculatus extract(COE) at different nontoxic concentrations(10,20,40,80,and 160 μg/mL).The effect of COE on HC-CLM6 viability was examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assays.Cellular apoptosis following COE treatment was assessed by flow cytometry and western blot analysis.RESULTS:COE significantly inhibited cell viability and induced apoptosis of HCCLM6 cells in a dose-dependent manner.Apoptosis was accompanied by increased Bax expression and decreased Bcl-2 expression.In addition,COE treatment led to the release of cytochrome c,activation of caspase-3,and cleavage of poly(ADP-ribose) polymerase(PARP).Furthermore,activation of extracellular signal-regulated kinase(ERK),p38 kinase,and c-Jun N-terminal kinase(JNK) phosphorylation,and down-regulation of Akt phosphorylation was observed.CONCLUSION:COE induces mitochondrial-mediated,caspase-dependent apoptosis in HCCLM6 cells,which might be attributed to the activation of mitogen-activated protein kinase(MAPK) and inhibition of Akt signaling pathways.These data suggest that COE may be a potential treatment for human hepatocellular carcinoma.

Key words: Celastrus, Apoptosis, Carcinoma,hepatocellular, Mitochondria, Caspases, Mitogen-activated protein kinase