title: Autophagy-related gene 7 (ATG7) and reactive oxygen species/extracellular signal-regulated kinase regulate tetrandrine-induced autophagy in human hepatocellular carcinoma.
abstract: Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the broadly used Chinese medicinal herb Stephaniae tetrandrae, exhibits potent antitumor effects and has the potential to be used as a cancer chemotherapeutic agent. We previously reported that high concentrations of tetrandrine induce apoptosis in liver cancer cells. Here, we found that in human hepatocellular carcinoma (HCC) cells, a low dose of tetrandrine (5 μm) induced the expression of LC3-II, resulted in the formation of acidic autophagolysosome vacuoles (AVOs), and caused a punctate fluorescence pattern with the GFP-LC3 protein, which all are markers for cellular autophagy. Tetrandrine induced the production of intracellular reactive oxygen species (ROS), and treatment with ROS scavengers significantly abrogated the tetrandrine-induced autophagy. These results suggest that the generation of ROS plays an important role in promoting tetrandrine-induced autophagy. Tetrandrine-induced mitochondrial dysfunction resulted in ROS accumulation and autophagy. ROS generation activated the ERK MAP kinase, and the ERK signaling pathway at least partially contributed to tetrandrine-induced autophagy in HCC cells. Moreover, we found that tetrandrine transcriptionally regulated the expression of autophagy related gene 7 (ATG7), which promoted tetrandrine-induced autophagy. In addition to in vitro studies, similar results were also observed in vivo, where tetrandrine caused the accumulation of ROS and induced cell autophagy in a tumor xenograft model. Interestingly, tetrandrine treatment also induced autophagy in a ROS-dependent manner in C. elegans muscle cells. Therefore, these findings suggest that tetrandrine is a potent autophagy agonist and may be a promising clinical chemotherapeutic agent.
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan 430072.
authors.forename: Ke
authors.initials: K
authors.lastname: Gong
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan 430072.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan 430072.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhan
authors.affiliation: College of Pharmacy, Wuhan University, Wuhan 430071, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Pharmacy, Wuhan University, Wuhan 430071, China.
authors.forename: Zebo
authors.initials: Z
authors.lastname: Huang
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan 430072. Electronic address: whli@whu.edu.cn.
authors.forename: Wenhua
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000493:pharmacokinetics*; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D000071193:Autophagy-Related Protein 7; D044182:Benzylisoquinolines / Q000737:chemistry / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects* / Q000235:genetics; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D031609:Stephania tetrandra / Q000737:chemistry; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D044764:Ubiquitin-Activating Enzymes / Q000096:biosynthesis* / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D044182:Benzylisoquinolines; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D017382:Reactive Oxygen Species; C009438:tetrandrine; D048049:Extracellular Signal-Regulated MAP Kinases; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes