title: Atg5 siRNA inhibits autophagy and enhances norcantharidin-induced apoptosis in hepatocellular carcinoma.
abstract: Cantharidin is a terpenoid isolated from Chinese blister beetles, and norcantharidin (NCTD) is a demethylated analog of cantharidin. It has been reported that cantharidin and norcantharidin have anticancer activities. Growing evidence suggests that inhibiting autophagy can induce apoptosis in the human hepatoma cell line HepG2. The objective of the present study was to determine whether inhibition of autophagy enhances NCTD-induced apoptosis in HepG2 cells. HepG2 cells were cultured in DMEM containing NCTD. Autophagy was upregulated in the presence of HBSS media supplemented with Ca2+ and Mg2+ and 10 mM HEPES and downregulated in the presence of 3-methyladenine (3-MA) and Atg5 siRNA. Autophagy, cell viability, and the expression of apoptotic proteins were assessed in HepG2 cells. Our data showed that cell apoptosis generally increased after norcantharidin treatment in HepG2 cells. Expression of LC3-II, an autophagosome marker, increased when cells were treated with HBSS media. It also increased cell viability. However, in the presence of 3-MA and Atg5 siRNA, autophagy was inhibited, LC3-II expression decreased and cell apoptosis increased. There was increased expression of Bax, cytochrome c, cleaved caspase-3, caspase-9 and PARP and the mitochondrial membrane potential was disrupted. Additionally, increased apoptosis was accompanied by increased reactive oxygen species (ROS) production. NCTD has anticancer activity, and Atg5 siRNA-mediated downregulation of autophagy enhanced its anticancer actions due to ROS generation and activation of the mitochondrial apoptosis pathway.
authors.affiliation: Department Of Gastroenterology 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Xuanxuan
authors.initials: X
authors.lastname: Xiong
authors.affiliation: Department Of Gastroenterology 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Mingbo
authors.initials: M
authors.lastname: Wu
authors.affiliation: Department Of Gastroenterology 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Oncological Surgery 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), The Tumor Research Institute of the Southeast University (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.affiliation: Department Of Gastroenterology 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Bo
authors.initials: B
authors.lastname: Lu
authors.affiliation: Department Of Gastroenterology 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Yonggao
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department Of Gastroenterology 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Tian
authors.initials: T
authors.lastname: Zhou
authors.affiliation: Department of Oncological Surgery 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), The Tumor Research Institute of the Southeast University (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Guo
authors.affiliation: Key Laboratory of Living Donor Liver Transplantation, Ministry of Public Health, Department of Liver Transplantation Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.
authors.forename: Rui
authors.initials: R
authors.lastname: Peng
authors.affiliation: Key Laboratory of Living Donor Liver Transplantation, Ministry of Public Health, Department of Liver Transplantation Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.
authors.forename: Xiangcheng
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Oncological Surgery 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), The Tumor Research Institute of the Southeast University (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Qingzhong
authors.initials: Q
authors.lastname: Tian
authors.affiliation: Department of Oncological Surgery 2, Xuzhou City Central Hospital, The Affiliated Hospital of the Southeast University Medical School (Xuzhou), The Tumor Research Institute of the Southeast University (Xuzhou), Xuzhou, Jiangsu 221009, P.R. China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D001343:Autophagy / Q000187:drug effects; D000071187:Autophagy-Related Protein 5; D015153:Blotting, Western; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D005455:Fluorescent Antibody Technique; D055785:Gene Knockdown Techniques; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection
chemical_list: C502778:ATG5 protein, human; D000970:Antineoplastic Agents; D000071187:Autophagy-Related Protein 5; D019086:Bridged Bicyclo Compounds, Heterocyclic; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C069741:norcantharidin