title: PTEN Activation by DNA Damage Induces Protective Autophagy in Response to Cucurbitacin B in Hepatocellular Carcinoma Cells.
abstract: Cucurbitacin B (Cuc B), a natural product, induced both protective autophagy and DNA damage mediated by ROS while the detailed mechanisms remain unclear. This study explored the mechanism of Cuc B-induced DNA damage and autophagy. Cuc B decreased cell viability in concentration- and time-dependent manners. Cuc B caused long comet tails and increased expression ofγ-H2AX, phosphorylation of ATM/ATR, and Chk1/Chk2. Cuc B induced autophagy as evidenced by monodansylcadaverine (MDC) staining, increased expression of LC3II, phosphorylated ULK1, and decreased expression of phosphorylated AKT, mTOR. Cuc B induced apoptosis mediated by Bcl-2 family proteins and caspase activation. Furthermore, Cuc B induced ROS formation, which was inhibited by N-acetyl-L-cysteine (NAC). NAC pretreatment dramatically reversed Cuc B-induced DNA damage, autophagy, and apoptosis. Cuc B-induced apoptosis was reversed by NAC but enhanced by 3-methyladenine (3-MA), chloroquine (CQ), and silencing phosphatase and tensin homolog (PTEN). 3-MA and CQ showed no effect on Cuc B-induced DNA damage. In addition, Cuc B increased PTEN phosphorylation and silence PTEN restored Cuc B-induced autophagic protein expressions without affecting DNA damage. In summary, Cuc B induced DNA damage, apoptosis, and protective autophagy mediated by ROS. PTEN activation in response to DNA damage bridged DNA damage and prosurvival autophagy.
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Science, University of Macau, Macau.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Niu
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Science, University of Macau, Macau.
authors.forename: Wen
authors.initials: W
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Science, University of Macau, Macau.
authors.forename: Jin-Jian
authors.initials: JJ
authors.lastname: Lu
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
authors.forename: Dik-Lung
authors.identifier: 0000-0002-9515-340X
authors.initials: DL
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Science, University of Macau, Macau.
authors.forename: Chung-Hang
authors.identifier: 0000-0003-2988-3786
authors.initials: CH
authors.lastname: Leung
authors.affiliation: Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China.
authors.forename: Lixia
authors.initials: L
authors.lastname: Pei
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Science, University of Macau, Macau.
authors.forename: Xiuping
authors.identifier: 0000-0003-2675-7645
authors.initials: X
authors.lastname: Chen
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects*; D004249:DNA Damage; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D009363:Neoplasm Proteins / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology*
chemical_list: D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species; D014315:Triterpenes; C041246:cucurbitacin B; D051059:PTEN Phosphohydrolase