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Open Access Highly Accessed Research article

MicroRNA-26b inhibits epithelial-mesenchymal transition in hepatocellular carcinoma by targeting USP9X

Gang Shen1, Ye Lin2, Xuewei Yang3, Jing Zhang1, Zhe Xu4 and Hongyun Jia5*

Author Affiliations

1 Department of interventional Radioloby and Vascular Anomalies, Affilated Guangzhou women and children’s medical center of Guangzhou Medical University, Guangzhou, China

2 Department of general surgery, Guangdong Gerernal Hospital, Guangzhou, China

3 Department of Hepatobiliary Surgery, the second affiliated hospital of Guangzhou Medical University, Guangzhou, China

4 Department of Pediatric Surgery, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China

5 Department of clinical examination, the second affiliated hospital of Guangzhou Medical University, Guangzhou, China

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BMC Cancer 2014, 14:393  doi:10.1186/1471-2407-14-393

Published: 2 June 2014

Abstract

Background

Metastasis is responsible for the rapid recurrence and poor survival of malignancies. Epithelial-mesenchymal transition (EMT) has a critical role in metastasis. Increasing evidence indicates that EMT can be regulated by microRNAs (miRNAs). The aim of this study was to investigate the role of miR-26b in modulating epithelial-mesenchymal transition (EMT) in hepatocellular carcinoma (HCC), as well as to identify its underlying mechanism of action.

Methods

The expression level of miR-26b was assessed in multiple HCC cell lines (HepG2, MHCC97H, Hep3B, MHCC97L, HCCC9810, BEL-7402, Huh7 and QGY-7703), as well as in liver tissue from patients with HCC. Follow-up studies examined the effects of a miR-26b mimic (increased expression) and a miR-26b inhibitor (decreased expression) on markers of EMT, wound healing and cell migration. The molecular target of miR-26b was also identified using a computer algorithm and confirmed experimentally.

Results

MiR-26b expression was decreased in HCC cell lines and was inversely correlated with the grade of HCC. Increased expression of miR-26b inhibited the migration and invasiveness of HCC cell lines, which was accompanied by decreased expression of the epithelial marker E-cadherin and increased expression of the mesenchymal marker vimentin, at both the mRNA and protein expression levels. A binding site for miR-26b was theoretically identified in the 3′UTR of USP9X. Further studies revealed that overexpression of miR-26b repressed the endogenous level of USP9X protein expression. Overexpression of miR-26b also repressed Smad4 expression, whereas its inhibition elevated Smad4 expression.

Conclusions

Taken together, our results indicate that miR-26b were inhibited in HCC. In HCC cell lines, miR-26b targeted the 3′UTR of USP9X, which in turn affects EMT through Smad4 and the TGF-β signaling pathway. Our analysis of clinical HCC samples verifies that miR-26b also targets USP9X expression to inhibit the EMT of hepatocytes. Thus, miR-26b may have some effects on the EMT of HCC cells.

Keywords:
miR-26; USP9X; Epithelial-mesenchymal transition; Hepatocellular carcinoma