title: Dulxanthone A induces cell cycle arrest and apoptosis via up-regulation of p53 through mitochondrial pathway in HepG2 cells.
abstract: Natural products derived from plants provide a rich source for development of new anticancer drugs. Dulxanthone A was found to be an active cytotoxic component in Garcinia cowa by bioactivity-directed isolation. Studies to elucidate the cytotoxic mechanisms of dulxanthone A showed that dulxanthone A consistently induced S phase arrest and apoptosis in the most sensitive cell line HepG2. Furthermore, p53 was dramatically up-regulated, leading to altered expression of downstream proteins upon dulxanthone A treatment. Cell cycle related proteins, such as cyclin A, cyclin B, cyclin E, cdc-2, p21 and p27 were down-regulated. Some apoptosis correlated proteins were also altered following the drug treatment. Bcl-2 family members PUMA was up-regulated while Bcl-2 and Bax were down-regulated. However, the expression ratio of Bax/Bcl-2 was increased. This resulted in the release of cytochrome C from the mitochondria to the cytosol. Concurrently, Apaf-1 was stimulated with p53 by dulxanthone A. In result, cytochrome C, Apaf-1 and procaspase-9 form an apoptosome, which in turn triggered the activation of caspase-9, caspase-3 and downstream caspase substrates. Lamin A/C and PARP were down-regulated or cleaved, respectively. Moreover, cell cycle arrest and apoptosis in HepG2 cells induced by dulxanthone A were markedly inhibited by siRNA knockdown of p53. In summary, dulxanthone A is an active cytotoxic component of G. cowa. It induces cell cycle arrest at lower concentrations and triggers apoptosis at higher concentrations via up-regulation of p53 through the intrinsic mitochondrial pathway in HepG2 cells. Dulxanthone A is therefore likely a promising preventive and/or therapeutic agent against Hepatoma.
authors.affiliation: Children's Hospital Informatics Program at Harvard- MIT Division of Health Sciences and Technology, Children's Hospital Boston, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Ze
authors.initials: Z
authors.lastname: Tian
authors.forename: Jie
authors.initials: J
authors.lastname: Shen
authors.forename: Annie P
authors.initials: AP
authors.lastname: Moseman
authors.forename: Quanli
authors.initials: Q
authors.lastname: Yang
authors.forename: Junshan
authors.initials: J
authors.lastname: Yang
authors.forename: Peigen
authors.initials: P
authors.lastname: Xiao
authors.forename: Erxi
authors.initials: E
authors.lastname: Wu
authors.forename: Isaac S
authors.initials: IS
authors.lastname: Kohane
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D029760:Garcinia / Q000737:chemistry; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D010936:Plant Extracts; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D020169:Caspases