Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jan 7, 2015; 21(1): 196-213
Published online Jan 7, 2015. doi: 10.3748/wjg.v21.i1.196
FoxM1 overexpression promotes epithelial-mesenchymal transition and metastasis of hepatocellular carcinoma
Fan-Di Meng, Ji-Chao Wei, Kai Qu, Zhi-Xin Wang, Qi-Fei Wu, Ming-Hui Tai, Hao-Chen Liu, Rui-Yao Zhang, Chang Liu
Fan-Di Meng, Ji-Chao Wei, Kai Qu, Zhi-Xin Wang, Ming-Hui Tai, Hao-Chen Liu, Rui-Yao Zhang, Chang Liu, Department of Hepatobiliary Surgery, the First Affiliated Hospital, School of Medicine, Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
Qi-Fei Wu, Department of Thoracic Surgery, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an 710061, Shaanxi Province, China
Author contributions: Meng FD performed the majority of the experiments and wrote the manuscript; Wei JC, Qu K, Wang ZX, Tai MH and Liu HC provided vital reagents and analytical tools; Zhang RY modified the language of the article; Wu QF edited the manuscript; Liu C designed the study and provided financial support for the experiments.
Supported by The National Natural Science Foundation of China, No. 30872482 and No. 81072051
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: Chang Liu, MD, PhD, Professor, Department of Hepatobiliary Surgery, the First Affiliated Hospital, School of Medicine, Xi’an Jiaotong University, 277 West Yan-ta Road, Xi’an 710061, Shaanxi Province, China. liuchangdoctor@163.com
Telephone: +86-29-82653900 Fax: +86-29-82653905
Received: July 2, 2014
Peer-review started: July 3, 2014
First decision: July 21, 2014
Revised: August 19, 2014
Accepted: October 15, 2014
Article in press: October 15, 2014
Published online: January 7, 2015
Processing time: 188 Days and 13.5 Hours
Abstract

AIM: To investigate the expression of forkhead box protein M1 (FoxM1) in the process of epithelial mesenchymal transition in hepatocellular carcinoma (HCC) and its role in metastasis.

METHODS: FoxM1 and E-cadherin expression in HCC tissue microarray specimens was evaluated by immunohistochemical staining, and statistical methods were applied to analyze the correlation between FoxM1 and epithelial-mesenchymal transition (EMT). Kaplan-Meier analysis of the correlation between the FoxM1 expression level and recurrence or overall survival of HCC patients was performed. The expression of FoxM1, E-cadherin and snail homologue 1 (SNAI1) in HCC cell lines was evaluated by real-time reverse transcription-polymerase chain reaction and Western blot. Hepatocyte growth factor (HGF) was used to induce EMT and stimulate cell migration in HCC cells. The expression of FoxM1 and SNAI1 was regulated by transfection with plasmids pcDNA3.1 and siRNAs in vitro. The occurrence of EMT was evaluated by Transwell assay, morphologic analysis and detection of the expression of EMT markers (E-cadherin and vimentin). Luciferase and chromatin immunoprecipitation assays were used to evaluate whether SNAI1 is a direct transcriptional target of FoxM1.

RESULTS: FoxM1 expression was increased significantly in HCC compared with para-carcinoma (10.7 ± 0.9 vs 8.2 ± 0.7, P < 0.05) and normal hepatic (10.7 ± 0.9 vs 2.7 ± 0.4, P < 0.05) tissues. Overexpression of FoxM1 was correlated with HCC tumor size, tumor number, macrovascular invasion and higher TNM stage, but was negatively correlated with E-cadherin expression in microarray specimens and in cell lines. FoxM1 overexpression was correlated significantly with HCC metastasis and EMT. In vitro, we found that FoxM1 plays a key role in HGF-induced EMT, and overexpression of FoxM1 could suppress E-cadherin expression and induce EMT changes, which were associated with increased HCC cell invasiveness. Next, we confirmed that FOXM1 directly binds to and activates the SNAI1 promoter, and we identified SNAI1 as a direct transcriptional target of FOXM1. Moreover, inhibiting the expression of SNAI1 significantly inhibited FoxM1-mediated EMT.

CONCLUSION: FoxM1 overexpression promotes EMT and metastasis of HCC, and SNAI1 plays a critical role in FoxM1-mediated EMT.

Keywords: Forkhead box protein M1; Epithelial-mesenchymal transition; Hepatocellular carcinoma; Snail homolog 1; E-cadherin

Core tip: Epithelial-mesenchymal transition (EMT) has emerged as a pivotal event affecting cancer invasion and metastasis, and forkhead box protein M1 (FoxM1) may regulate the EMT phenotype of pancreatic cancer cells by activation of mesenchymal cell markers. The present study demonstrated that FoxM1 plays a pivotal role in EMT and metastasis of hepatocellular carcinoma (HCC). Immunohistochemical analysis indicated that FoxM1 overexpression correlated significantly with HCC metastasis and EMT. In vitro, we found that FoxM1 plays a key role in HGF-induced EMT, and overexpression of FoxM1 could suppress E-cadherin expression and induce EMT changes by increasing snail homologue 1 expression.