Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. May 7, 2012; 18(17): 2035-2042
Published online May 7, 2012. doi: 10.3748/wjg.v18.i17.2035
Transactivation of the TIEG1 confers growth inhibition of transforming growth factor-β-susceptible hepatocellular carcinoma cells
Lei Jiang, Yiu-Kay Lai, Jin-Fang Zhang, Chu-Yan Chan, Gang Lu, Marie CM Lin, Ming-Liang He, Ji-Cheng Li, Hsiang-Fu Kung
Lei Jiang, Laboratory of Internal Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou 325000, Zhejiang Province, China
Yiu-Kay Lai, Department of Life Science, National Tsing Hua University, Hsinchu 30013, Taiwan
Jin-Fang Zhang, Chu-Yan Chan, Ming-Liang He, Hsiang-Fu Kung, Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Shatin 999077, Hong Kong, China
Gang Lu, Marie CM Lin, Brain Tumor Centre and Division of Neurosurgery, Department of Surgery, The Chinese University of Hong Kong, Shatin 999077, Hong Kong, China
Ji-Cheng Li, Institute of Cell Biology, Zhejiang University, Hangzhou 310058, Zhejiang Province, China
Author contributions: Jiang L, Chan CY, Lin MCM, He ML, Li JC and Kung HF designed the research; Jiang L, Zhang JF and Lu G performed the research; Jiang L, Lai YK, Lin MCM, He ML, Li JC and Kung HF analyzed the data; Jiang L, Lai YK and Chan CY wrote the paper.
Supported by Hong Kong Research Grant Council, No. 467109, 467507; the Scientific Research Fund of Zhejiang Provincial Education Department, No. Y200906317; the Wenzhou Science and Technology Bureau Program, No. Y20100017;Qianjiang Talents Project of Zhejiang Province, No.2011R10058
Correspondence to: Hsiang-Fu Kung, Professor, Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Shatin 999077, Hong Kong, China. hkung@cuhk.edu.hk
Telephone: +852-26037743 Fax: +852-29944988
Received: April 7, 2011
Revised: November 12, 2011
Accepted: February 26, 2012
Published online: May 7, 2012
Abstract

AIM: 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.

CONCLUSION: Our data suggest that transactivation of TIEG1 conferred growth inhibition of TGF-β-susceptible human HCC cells.

Keywords: Growth inhibition; Hepatocellular carcinoma; Stathmin; Transforming growth factor-β; Transforming growth factor-β-inducible early gene 1