Original Article
Copyright ©2014 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 7, 2014; 20(21): 6523-6533
Published online Jun 7, 2014. doi: 10.3748/wjg.v20.i21.6523
IGFBPrP1 induces liver fibrosis by inducing hepatic stellate cell activation and hepatocyte apoptosis via Smad2/3 signaling
Yun Zhang, Qian-Qian Zhang, Xiao-Hong Guo, Hai-Yan Zhang, Li-Xin Liu
Yun Zhang, Department of Gastroenterology and Hepatology, First Hospital of Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
Qian-Qian Zhang, Xiao-Hong Guo, Hai-Yan Zhang, Li-Xin Liu, Department of Gastroenterology and Hepatology, First Hospital of Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
Qian-Qian Zhang, Xiao-Hong Guo, Hai-Yan Zhang, Li-Xin Liu, Experimental Centre of Science and Research, The First Clinical Hospital of Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
Qian-Qian Zhang, Xiao-Hong Guo, Hai-Yan Zhang, Li-Xin Liu, Key Laboratory of Cell Physiology, Provincial Department of the Ministry of Education, Shanxi Medical University, Taiyuan 030001, Shanxi Province, China
Author contributions: Liu LX designed the study; Zhang Y analyzed the data and wrote the paper; Zhang QQ, Guo XH and Zhang HY performed the experiments.
Supported by National Natural Science Foundation of China, No. 30871146 and No. 81141049; and Shanxi Provincial Key Scientific Research Projects for the Returned Scholars, 2012-4
Correspondence to: Li-Xin Liu, Professor, Department of Gastroenterology and Hepatology, First Hospital of Shanxi Medical University, Xinjiannan Rd 56, Taiyuan 030001, Shanxi Province, China. lixinliu6@hotmail.com
Telephone: +86-351-4639075  Fax: +86-351-8263169
Received: November 11, 2013
Revised: January 14, 2014
Accepted: February 20, 2014
Published online: June 7, 2014
Abstract

AIM: To investigate the role and mechanism of insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) in the development of liver fibrosis.

METHODS: An in vitro model using hepatic stellate cell (HSC)-T6 cells and an in vivo model of rat liver overexpressing IGFBPrP1 were established using an IGFBPrP1-expressing recombinant adenovirus. The expression of IGFBPrP1 was examined by immunofluorescence, and the expression of collagen I and fibronectin was measured by real-time reverse transcription-polymerase chain reaction and Western blot analysis. The expression of Smad2/3 and p-Smad2/3 was examined by Western blot and immunohistochemistry. A shSmad3-expressing recombinant adenovirus (AdshSmad3) was designed and used to knockdown the Smad3 gene in HSC-T6 cells and rat liver fibrosis transfected with IGFBPrP1. The expression of collagen I, fibronectin, and α-smooth muscle actin (α-SMA) was determined by Western blot analysis and immunohistochemistry. Hepatocyte apoptosis was assessed using TUNEL assay.

RESULTS: IGFBPrP1 overexpression induced collagen deposition and up-regulated the expression of α-SMA and p-Smad2/3, and AdshSmad3 inhibited IGFBPrP1-stimulated p-Smad2/3 activation and the expression of α-SMA, collagen I and fibronectin in HSC-T6 cells. Similarly, increased hepatocyte apoptosis (38.56% ± 3.42% vs 0.24% ± 0.03%, P < 0.05), α-SMA positive stained cells (29.84% ± 1.36% vs 5.83% ± 1.47%, P < 0.05), and increased numbers of Smad3 (35.88% ± 2.15% vs 10.24% ± 1.31%, P < 0.05) and p-Smad2/3 positive cells (28.87% ± 2.73% vs 8.23% ± 0.98%, P < 0.05) were detected in the livers of IGFBPrP1-overexpressing rats compared with the control group. Moreover, AdshSmad3 reduced IGFBPrP1-stimulated Smad3 expression and attenuated α-SMA expression (29.84% ± 1.36% vs 8.23% ± 1.28%, P < 0.05), hepatocyte apoptosis (38.56% ± 3.42% vs 6.75% ± 0.52%, P < 0.05), and both collagen I and fibronectin deposition in the livers of AdIGFBPrP1-treated rats.

CONCLUSION: IGFBPrP1 induces liver fibrosis by mediating the activation of hepatic stellate cells and hepatocyte apoptosis in a Smad3-dependent mechanism.

Keywords: Insulin-like growth factor binding protein-related protein 1, Liver fibrosis, Hepatic stellate cells, Hepatocyte apoptosis, Smad pathway

Core tip: This study investigated the role and mechanism of insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) in liver fibrosis using an adenovirus vector carrying IGFBPrP1 or a small interfering RNA targeting Smad3. We found that overexpression of IGFBPrP1 induced liver fibrosis by mediating hepatocyte apoptosis and hepatic stellate cells activation. We also identified the important role of the IGFBPrP1-Smad pathway in the regulation of IGFBPrP1 action in the development of liver fibrosis, and this pathway is a potential therapeutic target for liver fibrosis.