title: Fangchinoline induces autophagic cell death via p53/sestrin2/AMPK signalling in human hepatocellular carcinoma cells.
abstract: OBJECTIVE
  Fangchinoline is a novel anti-tumour agent with little known of its cellular and molecular mechanisms of action. Here we have investigated the mode of cell death induced by fangchinoline and its underlying mechanism in two human hepatocellular carcinoma cell lines, HepG2 and PLC/PRF/5.
  
  
  METHODS
  Apoptosis and autophagy were monitored in fangchinoline-treated HepG2 and PLC/PRF/5 cells by histological methods. The signal transduction pathways involved in activation of autophagy were examined, using immunoblotting, real-time PCR and siRNA techniques.
  
  
  RESULTS
  Fangchinoline did not induce apoptosis in HepG2 and PLC/PRF/5 cells but triggered, dose-dependently, autophagy, an alternative mode of cell death which may contribute to fangchinoline's anti-tumour action. Nuclear translocation of p53 was involved in induction of autophagy by fangchinoline, followed by selective transactivation of the autophagy-related gene sestrin2 and initiation of the autophagic process. Signalling by the AMP-activated protein kinase was also involved as a downstream target of sestrin2 and induced mTOR-independent autophagic cell death in both cell lines. siRNA for Atg 5 or pharmacological block of p53 abolished fangchinoline-induced autophagy and inhibition of autophagy switched cell death to apoptosis in these cells, suggesting that cell death is irreversible once autophagy is induced by fangchinoline.
  
  
  CONCLUSIONS
  Fangchinoline is a highly specific agent inducing autophagic cell death in hepatocellular carcinoma cells with a novel mechanism, which elucidates the potential of fangchinoline to potentiate programmed cell death in cancer cells.
authors.affiliation: School of Chinese Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.forename: Weidong
authors.initials: W
authors.lastname: Pan
authors.forename: Meifen
authors.initials: M
authors.lastname: Zhu
authors.forename: Maosheng
authors.initials: M
authors.lastname: Zhang
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Hao
authors.forename: Guangyi
authors.initials: G
authors.lastname: Liang
authors.forename: Yibin
authors.initials: Y
authors.lastname: Feng
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D044182:Benzylisoquinolines / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D011506:Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D000084622:Sestrins
chemical_list: D055372:AMP-Activated Protein Kinases; D000970:Antineoplastic Agents; D044182:Benzylisoquinolines; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011506:Proteins; D058570:TOR Serine-Threonine Kinases; D016159:Tumor Suppressor Protein p53; C512709:DRAM1 protein, human; C465398:SESN2 protein, human; D000084622:Sestrins; C495901:TP53 protein, human; C060802:fangchinoline; C546842:MTOR protein, human