title: Hepatitis C virus core protein down-regulates p21(Waf1/Cip1) and inhibits curcumin-induced apoptosis through microRNA-345 targeting in human hepatoma cells.
abstract: BACKGROUND
  Hepatitis C virus (HCV) has been reported to regulate cellular microRNAs. The HCV core protein is considered to be a potential oncoprotein in HCV-related hepatocellular carcinoma, but HCV core-modulated cellular microRNAs are unknown. The HCV core protein regulates p21(Waf1/Cip1) expression. However, the mechanism of HCV core-associated p21(Waf1/Cip1) regulation remains to be further clarified. Therefore, we attempted to determine whether HCV core-modulated cellular microRNAs play an important role in regulating p21(Waf1/Cip1) expression in human hepatoma cells.
  
  
  METHODS
  Cellular microRNA profiling was investigated in core-overexpressing hepatoma cells using TaqMan low density array. Array data were further confirmed by TaqMan real-time qPCR for single microRNA in core-overexpressing and full-length HCV replicon-expressing cells. The target gene of microRNA was examined by reporter assay. The gene expression was determined by real-time qPCR and Western blotting. Apoptosis was examined by annexin V-FITC apoptosis assay. Cell cycle analysis was performed by propidium iodide staining. Cell proliferation was analyzed by MTT assay.
  
  
  RESULTS
  HCV core protein up- or down-regulated some cellular microRNAs in Huh7 cells. HCV core-induced microRNA-345 suppressed p21(Waf1/Cip1) gene expression through targeting its 3' untranslated region in human hepatoma cells. Moreover, the core protein inhibited curcumin-induced apoptosis through p21(Waf1/Cip1)-targeting microRNA-345 in Huh7 cells.
  
  
  CONCLUSIONS
  HCV core protein enhances the expression of microRNA-345 which then down-regulates p21(Waf1/Cip1) expression. It is the first time that HCV core protein has ever been shown to suppress p21(Waf1/Cip1) gene expression through miR-345 targeting.
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Tzu-Yue
authors.initials: TY
authors.lastname: Shiu
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Huang
authors.forename: Yu-Lueng
authors.initials: YL
authors.lastname: Shih
authors.forename: Heng-Cheng
authors.initials: HC
authors.lastname: Chu
authors.forename: Wei-Kuo
authors.initials: WK
authors.lastname: Chang
authors.forename: Tsai-Yuan
authors.initials: TY
authors.lastname: Hsieh
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D045744:Cell Line, Tumor; D003474:Curcumin / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics*; D015536:Down-Regulation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D016174:Hepacivirus / Q000378:metabolism / Q000502:physiology; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics*; D058990:Molecular Targeted Therapy; D014758:Viral Core Proteins / Q000378:metabolism*
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; C561417:MIRN345 microRNA, human; C543350:MIRN93 microRNA, human; D035683:MicroRNAs; D014758:Viral Core Proteins; C069130:nucleocapsid protein, Hepatitis C virus; D003474:Curcumin