Brief Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Dec 21, 2012; 18(47): 7070-7078
Published online Dec 21, 2012. doi: 10.3748/wjg.v18.i47.7070
Connective tissue growth factor is overexpressed in human hepatocellular carcinoma and promotes cell invasion and growth
Ming Xiu, Ya-Hui Liu, David R Brigstock, Fang-Hui He, Rui-Juan Zhang, Run-Ping Gao
Ming Xiu, Fang-Hui He, Rui-Juan Zhang, Run-Ping Gao, Department of Hepatic-Biliary-Pancreatic Medicine, First Hospital, Jilin University, Changchun 130021, Jilin Province, China
Ya-Hui Liu, Department of Hepatic-Biliary-Pancreatic Surgery, First Hospital, Jilin University, Changchun 130021, Jilin Province, China
David R Brigstock, the Research Institute at Nationwide Children’s Hospital, Columbus, OH 43205, United States
David R Brigstock, Division of Pediatric Surgery, Department of Surgery, the Ohio State University, Columbus, OH 43205, United States
Author contributions: Xiu M, He FH and Zhang RJ performed the majority of the experiments; Liu YH contributed the study design, data collection; Gao RP designed the study and wrote the manuscript; Brigstock DR co-ordinated the study and edited the manuscript; Xiu M and Liu YH contributed equally to the paper.
Supported by National Natural Scientific Foundation, No. 30872236, 81070370, to Gao RP; and NIH 5R01AA016003, to Brigstock DR
Correspondence to: Run-Ping Gao, Professor, Department of Hepatic-Biliary-Pancreatic Medicine, First Hospital, Jilin University, 71 Xinmin Avenue, Changchun 130021, Jilin Province, China. gao_runping@yahoo.com
Telephone: +86-431-88783929 Fax: +86-431-85612468
Received: July 17, 2012
Revised: November 13, 2012
Accepted: November 24, 2012
Published online: December 21, 2012
Abstract

AIM: To determine the expression characteristics of connective tissue growth factor (CTGF/CCN2) in human hepatocellular carcinoma (HCC) in histology and to elucidate the roles of CCN2 on hepatoma cell cycle progression and metastasis in vitro.

METHODS: Liver samples from 36 patients (who underwent hepatic resection for the first HCC between 2006 and 2011) and 6 normal individuals were examined for transforming growth factor β1 (TGF-β1) or CCN2 mRNA by in situ hybridization. Computer image analysis was performed to measure integrated optimal density of CCN2 mRNA-positive cells in carcinoma foci and the surrounding stroma. Fibroblast-specific protein-1 (FSP-1) and E-cadherin were examined to evaluate the process of epithelial to mesenchymal transition, α-smooth muscle actin and FSP-1 were detected to identify hepatic stellate cells, and CD34 was measured to evaluate the extent of vascularization in liver tissues by immunohistochemical staining. CCN2 was assessed for its stimulation of HepG2 cell migration and invasion using commercial kits while flow cytometry was used to determine CCN2 effects on HepG2 cell-cycle.

RESULTS: In situ hybridization analysis showed that TGF-β1 mRNA was mainly detected in connective tissues and vasculature around carcinoma foci. In comparison to normal controls, CCN2 mRNA was enhanced 1.9-fold in carcinoma foci (12.36 ± 6.08 vs 6.42 ± 2.35) or 9.4-fold in the surrounding stroma (60.27 ± 28.71 vs 6.42 ± 2.35), with concomitant expression of CCN2 and TGF-β1 mRNA in those areas. Epithelial-mesenchymal transition phenotype related with CCN2 was detected in 12/36 (33.3%) of HCC liver samples at the edges between carcinoma foci and vasculature. Incubation of HepG2 cells with CCN2 (100 ng/mL) resulted in more of the cells transitioning into S phase (23.85 ± 2.35 vs 10.94 ± 0.23), and induced a significant migratory (4.0-fold) and invasive (5.7-fold) effect. TGF-β1-induced cell invasion was abrogated by a neutralizing CCN2 antibody showing that CCN2 is a downstream mediator of TGF-β1-induced hepatoma cell invasion.

CONCLUSION: These data support a role for CCN2 in the growth and metastasis of HCC and highlight CCN2 as a potential novel therapeutic target.

Keywords: Connective tissue growth factor; Hepatocellular carcinoma; Hepatoma cell line; Migration; Invasion