title: Transactivation of the TIEG1 confers growth inhibition of transforming growth factor-β-susceptible hepatocellular carcinoma cells.
abstract: OBJECTIVE
  To investigate the role of transforming growth factor (TGF)-β-inducible early gene 1 (TIEG1) in TGF-β-induced growth inhibition in hepatocellular carcinoma (HCC) cells.
  
  
  METHODS
  Human hepatocyte and HCC cell lines with varied susceptibilities to TGF-β1 were tested by methylthiazoletetrazolium (MTT) assay. The expression changes of Smad2, Smad3, Smad4, Smad7, TIEG1 and TIEG2 gene following treatment with TGF-β1 in a TGF-β-sensitive hepatocyte cell line (MIHA), a TGF-β-sensitive hepatoma cell line (Hep3B) and two TGF-β-insensitive hepatoma cell lines (HepG2 and Bel7404) were examined. SiRNA targeting TIEG1 was transfected into Hep3B cells and the sensitivity of cells to TGF-β1 was examined. Overexpression of TIEG1 was induced by lentiviral-mediated transduction in TGF-β1-resistant hepatoma cell lines (Bel7404 and HepG2). MTT assay and 4',6-Diamidino-2-phenylindole staining were used to identify cell viability and apoptosis, respectively. The expression level of stathmin was measured by reverse transcriptase polymerase chain reaction and Western-blotting analysis, and stathmin promoter activity by TIEG1 was monitored by a luciferase reporter gene system.
  
  
  RESULTS
  TIEG1 was significantly upregulated by TGF-β1 in the TGF-β1-sensitive HCC cell line, Hep3B, but not in the resistant cell lines. The suppression of TIEG1 by siRNAs decreased the sensitivity of Hep3B cells to TGF-β1, whereas the overexpression of TIEG1 mediated growth inhibition and apoptosis in TGF-β1-resistant HCC cell lines, which resembled those of TGF-β1-sensitive HCC cells treated with TGF-β1. Our data further suggested that stathmin was a direct target of TIEG1, as stathmin was significantly downregulated by TIEG1 overexpression, and stathmin promoter activity was inhibited by TIEG1 in a dose-dependent manner.
  
  
  CONCLUSIONS
  Our data suggest that transactivation of TIEG1 conferred growth inhibition of TGF-β-susceptible human HCC cells.
authors.affiliation: Laboratory of Internal Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou 325000, Zhejiang Province, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang
authors.forename: Yiu-Kay
authors.initials: YK
authors.lastname: Lai
authors.forename: Jin-Fang
authors.initials: JF
authors.lastname: Zhang
authors.forename: Chu-Yan
authors.initials: CY
authors.lastname: Chan
authors.forename: Gang
authors.initials: G
authors.lastname: Lu
authors.forename: Marie Cm
authors.initials: MC
authors.lastname: Lin
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: He
authors.forename: Ji-Cheng
authors.initials: JC
authors.lastname: Li
authors.forename: Hsiang-Fu
authors.initials: HF
authors.lastname: Kung
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D051765:Early Growth Response Transcription Factors / Q000502:physiology*; D022781:Hepatocytes / Q000187:drug effects; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000502:physiology*; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000473:pathology; D011401:Promoter Regions, Genetic; D051785:Smad Proteins / Q000378:metabolism; D050777:Stathmin / Q000235:genetics; D015533:Transcriptional Activation; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
chemical_list: D051765:Early Growth Response Transcription Factors; C098111:KLF10 protein, human; D051741:Kruppel-Like Transcription Factors; D051785:Smad Proteins; D050777:Stathmin; D053773:Transforming Growth Factor beta1