Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Feb 21, 2018; 24(7): 819-832
Published online Feb 21, 2018. doi: 10.3748/wjg.v24.i7.819
Metformin attenuates motility, contraction, and fibrogenic response of hepatic stellate cells in vivo and in vitro by activating AMP-activated protein kinase
Zhen Li, Qian Ding, Li-Ping Ling, Ying Wu, Dong-Xiao Meng, Xiao Li, Chun-Qing Zhang
Zhen Li, Qian Ding, Li-Ping Ling, Ying Wu, Dong-Xiao Meng, Xiao Li, Chun-Qing Zhang, Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan 250021, Shandong Province, China
Zhen Li, Li-Ping Ling, Ying Wu, Dong-Xiao Meng, Xiao Li, Shandong Provincial Engineering and Technological Research Center for Liver Disease Prevention and Control, Jinan 250021, Shandong Province, China
Author contributions: Li Z, Ding Q, Ling LP, Wu Y and Meng DX performed the study; Li Z, Ding Q and Li X collected and analyzed the data and edited the manuscript; Li Z and Zhang CQ designed the study and wrote the manuscript.
Supported by National Natural Science Foundation of China, No. 81370590.
Institutional review board statement: The study was reviewed and approved by the Institutional Review Board of Shandong Provincial Hospital Affiliated to Shandong University.
Institutional animal care and use committee statement: The consent procedure and study protocol were approved by the Animal Medical Ethics Committee of Shandong Provincial Hospital Affiliated to Shandong University (No. 2017-228).
Conflict-of-interest statement: The authors declare no conflict of interest related to this manuscript.
Data sharing statement: No additional unpublished data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Chun-Qing Zhang, PhD, Chief Doctor, Department of Gastroenterology, Shandong Provincial Hospital Affiliated to Shandong University, 324 Jingwu Weiqi Road, Jinan 250021, Shandong Province, China. zhangchunqing_sdu@163.com
Telephone: +86-531-68773293 Fax: +86-531-87906348
Received: November 21, 2017
Peer-review started: November 21, 2017
First decision: December 6, 2017
Revised: December 12, 2017
Accepted: December 26, 2017
Article in press: December 26, 2017
Published online: February 21, 2018
Processing time: 79 Days and 23.9 Hours
Abstract
AIM

To investigate the effect of metformin on activated hepatic stellate cells (HSCs) and the possible signaling pathways involved.

METHODS

A fibrotic mouse model was generated by intraperitoneal injection of carbon tetrachloride (CCl4) and subsequent treatment with or without metformin. The level of fibrosis was detected by hematoxylin-eosin staining, Sirius Red staining, and immunohistochemistry. The HSC cell line LX-2 was used for in vitro studies. The effect of metformin on cell proliferation (CCK8 assay), motility (scratch test and Transwell assay), contraction (collagen gel contraction assay), extracellular matrix (ECM) secretion (Western blot), and angiogenesis (ELISA and tube formation assay) was investigated. We also analyzed the possible signaling pathways involved by Western blot analysis.

RESULTS

Mice developed marked liver fibrosis after intraperitoneal injection with CCl4 for 6 wk. Metformin decreased the activation of HSCs, reduced the deposition of ECM, and inhibited angiogenesis in CCl4-treated mice. Platelet-derived growth factor (PDGF) promoted the fibrogenic response of HSCs in vitro, while metformin inhibited the activation, proliferation, migration, and contraction of HSCs, and reduced the secretion of ECM. Metformin decreased the expression of vascular endothelial growth factor (VEGF) in HSCs through inhibition of hypoxia inducible factor (HIF)-1α in both PDGF-BB treatment and hypoxic conditions, and it down-regulated VEGF secretion by HSCs and inhibited HSC-based angiogenesis in hypoxic conditions in vitro. The inhibitory effects of metformin on activated HSCs were mediated by inhibiting the Akt/mammalian target of rapamycin (mTOR) and extracellular signal-regulated kinase (ERK) pathways via the activation of adenosine monophosphate-activated protein kinase (AMPK).

CONCLUSION

Metformin attenuates the fibrogenic response of HSCs in vivo and in vitro, and may therefore be useful for the treatment of chronic liver diseases.

Keywords: Hepatic stellate cell; Intrahepatic vascular resistance; Angiogenesis; Contraction; Liver fibrosis; Adenosine monophosphate-activated protein kinase

Core tip: Activation of hepatic stellate cells (HSCs) contributes to liver fibrosis and portal hypertension. In this study, we examined the effect of metformin on activated HSCs in vivo and in vitro. Metformin decreased the activation of HSCs, reduced the deposition of extracellular matrix (ECM), and inhibited angiogenesis in CCl4-treated mice. Moreover, metformin inhibited the activation, proliferation, motility, and contraction of activated HSCs, reduced the secretion of ECM, and decreased HSC-based angiogenesis, thus providing a new therapeutic approach to the treatment of liver fibrosis and portal hypertension.