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Data sharing statement: No additional unpublished data are available.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
ARTICLE HIGHLIGHTS
Research background

Activation of hepatic stellate cells (HSCs) contributes to liver fibrosis and portal hypertension, and it is a therapeutic target for the treatment of chronic liver diseases (CLDs). Previous studies have demonstrated that metformin has a wide range of pharmacological activities beyond its antidiabetic effects. It may therefore represent a potent therapeutic approach to CLDs, but the mechanisms underlying its effects are still unclear.

Research motivation

This study was performed to investigate the effect of metformin on activated HSCs and clarify its molecular mechanisms.

Research objectives

The inhibitory effects of metformin on the activation, proliferation, motility, contraction, extracellular matrix (ECM) secretion of HSCs and HSC-based angiogenesis were evaluated. We also characterized its underlying mechanisms with a focus on AMPK and downstream AKT/mTOR and ERK signaling pathways.

Research methods

The effect of metformin on activated HSCs were investigated in vivo and in vitro. A fibrotic mouse model was treated with or without metformin, and the effect of metformin on liver fibrosis was evaluated. The HSC cell line LX-2 was used for in vitro studies. The effect of metformin on cell proliferation was detected by CCK8 assay. Cell motility was measured by scratch tests and Transwell assays. Collagen gel contraction assays were performed to assess the effect of metformin on cell contraction. Expression of α-SMA, collagen type I, and fibronectin was determined by Western blot analysis. We also analyzed the effect of metformin on HSC-based angiogenesis in both PDGF and hypoxic conditions. The phosphorylation levels of AMPK, AKT, mTOR, and ERK were measured by Western blot analysis. We also used the indicated pharmacologic inhibitors and agonists to confirm our findings.

Research results

Metformin decreased the activation of HSCs, reduced the deposition of ECM, and inhibited angiogenesis in fibrotic mice. PDGF-BB promoted the fibrogenic response of HSCs, while metformin inhibited the activation, proliferation, migration, and contraction of HSCs, reduced their secretion of ECM, and decreased HSC-based angiogenesis. These inhibitory effects were mediated by inhibition of the Akt/mTOR and ERK pathways via the activation of AMPK.

Research conclusions

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

Research perspective

This study investigated the inhibitory effect of metformin on activated HSCs and the possible signaling pathways involved. The results strongly confirmed the potential use of metformin for the treatment of CLDs. In future studies, we will provide more evidence for the use of metformin, especially in the treatment of portal hypertension. The effect of metformin on liver sinusoidal endothelial cells will also be analyzed.