Chaga mushroom （Inonotus obliquus） induces G0/G1 arrest and apoptosis in human hepatoma HepG2 cells

AIM： To investigate the anti-proliferative and apoptotic effects of Chaga mushroom （Inonotus obliquus） water extract on human hepatoma cell lines, HepG2 and Hep3B cells. METHODS： The cytotoxicity of Chaga extract was screened by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide （MTT） assay. Morphological observation, flow cytometry analysis, Western blot were employed to elucidate the cytotoxic mechanism of Chaga extract. RESULTS： HepG2 cells were more sensitive to Chaga extract than Hep3B cells, as demonstrated by markedly reduced cell viability. Chaga extract inhibited the cell growth in a dose-dependent manner, which was accompanied with G0/G1-phase arrest and apoptotic cell death. In addition, G0/G1 arrest in the cell cycle was closely associated with down-regulation of p53, pRb, p27, cyclins D1, D2, E, cyclin-dependent kinase （Cdk） 2, Cdk4, and Cdk6 expression. CONCLUSION： Chaga mushroom may provide a new therapeutic option, as a potential anticancer agent, in the treatment of hepatoma.