title: Hellebrigenin induces cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells through inhibition of Akt.
abstract: Hellebrigenin, one of bufadienolides belonging to cardioactive steroids, was found in skin secretions of toads and plants of Helleborus and Kalanchoe genera. In searching for natural constituents with anti-hepatoma activities, we found that hellebrigenin, isolated from traditional Chinese medicine Venenum Bufonis, potently reduced the viability and colony formation of human hepatocellular carcinoma cells HepG2, and went on to explore the underlying molecular mechanisms. Our results demonstrated that hellebrigenin triggered DNA damage through DNA double-stranded breaks and subsequently induced cell cycle G2/M arrest associated with up-regulation of p-ATM (Ser(1981)), p-Chk2 (Tyr(68)), p-CDK1 (Tyr(15)) and Cyclin B1, and down-regulation of p-CDC25C (Ser(216)). It was also found that hellebrigenin induced mitochondrial apoptosis, characterized by Bax translocation to mitochondria, disruption of mitochondrial membrane potential, release of cytochrome c into cytosol and sequential activation of caspases and PARP. In addition, Akt expression and phosphorylation were inhibited by hellebrigenin, whereas Akt silencing with siRNA significantly blocked cell cycle arrest but enhanced apoptosis induced by hellebrigenin. Activation of Akt by human insulin-like growth factor I (hIGF-I) could obviously attenuate hellebrigenin-induced cell death. In summary, our study is the first to report the efficacy of hellebrigenin against HepG2 and elucidated its molecular mechanisms including DNA damage, mitochondria collapse, cell cycle arrest and apoptosis, which will contribute to the development of hellebrigenin into a chemotherapeutic agent in the treatment of liver cancer.
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Li-Juan
authors: LJ
authors: Deng
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Li-Ping
authors: LP
authors: Hu
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Qun-Long
authors: QL
authors: Peng
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Xiao-Lin
authors: XL
authors: Yang
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Liang-Liang
authors: LL
authors: Bai
authors: School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors: Anita
authors: A
authors: Yiu
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Yong
authors: Y
authors: Li
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China.
authors: Hai-Yan
authors: HY
authors: Tian
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China. Electronic address: chyewc@gmail.com.
authors: Wen-Cai
authors: WC
authors: Ye
authors: Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, China. Electronic address: dmzhang701@foxmail.com.
authors: Dong-Mei
authors: DM
authors: Zhang
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002018:Bufanolides / Q000494:pharmacology* / Q000627:therapeutic use; D016203:CDC2 Protein Kinase; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000201:enzymology; D059447:Cell Cycle Checkpoints / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D064447:Checkpoint Kinase 2 / Q000378:metabolism; D020552:Comet Assay; D056744:Cyclin B1 / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004249:DNA Damage / Q000502:physiology; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000201:enzymology; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020687:cdc25 Phosphatases / Q000378:metabolism
chemical_list: D002018:Bufanolides; C534699:CCNB1 protein, human; D056744:Cyclin B1; C001330:hellebrigenin; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D051057:Proto-Oncogene Proteins c-akt; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; D018844:Cyclin-Dependent Kinases; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases
keywords: Akt; Apoptosis; Cell cycle; DNA damage; Hellebrigenin; Hepatocellular carcinoma