miR-139-5p and inhibits invasion and metastasis of hepatoma cells by targeting TGF-β1

Objective To investigate the molecular mechanism of miR-139-5p targeting transforming growth factor-β1 (TGF-β1) in the regulation of epithelial mesenchymal transition (EMT), thus inhibiting invasion and metastasis of hepatoma cells. Methods Bioinformatics methods were used to determine whether miR-139-5p was the best binding miRNA of TGF-β1. Correlation between the TGF-β1 expression as detected by immunohistochemistry and Western blot, and the miR-139-5p level by qRT-PCR in 56 hepatoma tissues and 20 normal tissues, respectively, was analyzed. The relationship between the miR-139-5p level as detected by qRT-PCR, and TGF-β1, E-cadherin and Vimentin by Western blot in the high and low metastatic hepatoma cell lines were investigated. In recombinant cell lines, whether miR-139-5p could bind to the 3`UTR site of TGF-β1 was evaluated, and the effect on invasive ability after modulating miR-139-5p level was also tested by the transwell method. Results A total of 20 miRNAs were found to be able to bind with TGF-β1 by bioinformatics methods and among these mRNAs, miR-139-5p was the best target miRNA with the highest specificity and strongest stability to bind TGF-β1. The positive expression rates of TGF-β1 in hepatoma tissues and adjacent normal liver tissues were 80.4%(45/56) and 15.0%(3/20), respectively, (P<0.05). There were significant differences on the expressions of TGF-β1, E-cadherin and Vimentin among the different metastatic cell lines (all P<0.05). After miR-139-5p was transfected into hepatoma cells, miR-139-5p could bind to the 3`UTR site of TGF-β1, resulting in downregulating TGF-β1 expression. When compared to the other three groups, the cell line with a high expression of miR-139-5p had a significantly lower count of invasive cells (53±4/ high magnification field) (P<0.05). Conclusion miRNA-139-5p could specifically bind to the 3`UTR site of TGF-β1 and regulate the EMT signaling pathway, thus suppressing invasion and metastasis of hepatoma cells. Key words: miRNA; Hepatoma; Invasion and metastasis; Transforming growth factor-β1; Epithelial-mesenchymal transition signaling pathway