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 G(0)/G(1)-phase arrest and apoptotic cell death. In addition, G(0)/G(1) 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. (c) 2008 WJG. All rights reserved.