Suppressive effects of microRNA-16 on the proliferation, invasion and metastasis of hepatocellular carcinoma cells

Abstract

miR-16 is known to be abnormally expressed in hepatocellular carcinoma (HCC) cells, and the overexpression of miR-16 inhibits the proliferation, invasion and metastasis of various cancer cells. MicroRNAs (miRNAs or miRs) are closely related to the proliferation, invasion and metastasis of HCC. The present study aimed to explore the effects of miR-16 on the proliferation, invasion and metastasis of HCC cells, and to elucidate the mechanisms involved. A cell line with moderate levels of miR-16 expression was selected from the SMMC-7721, HepG2, SK-Hep-1 and Huh-7 HCC cells and validated by reverse transcription-PCR (RT-PCR). The effects of miR-16 on HCC cell viability were determined by MTT assay; cell migration and invasion were determined by Transwell cell invasion assay, and apoptosis was determined by flow cytometery (FCM). Western blot analysis was used to measure the expression levels of the apoptosis-related proteins, Bax, Bcl-2, matrix metalloproteinase (MMP)-2, MMP-9, as well as to examine epithelial-mesenchymal transition (EMT), and E-cadherin, vimentin, and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway-related protein expression. The mRNA expression levels of miR-16 were highest in the SMMC-7721 cells and lowest in the SK-Hep-1 and Huh-7 cells; moderate levels were observed in the HepG2 cells. The HepG2 cell line was selected as the cell line for use in the follow-up experiments, where we measured cell viability, and the expression of PI3k/Akt, Bax, Bcl-2, MMP-2 and MMP-9, and E-cadherin and vimentin. miR-16 overexpression significantly inhibited the proliferation, invasion and metastasis of the HepG2 cells, as shown by western blot anlaysis. This was achieved through the upregulation of Bax expression, the downregulation of Bcl-2 expression and the decrease in the expression of MMP-2 and MMP-9. In addition the epxression of E-cadherin increased and vimentin expression decreased. miR-16 overexpression inhibited PI3K expression and Akt phosphorylation. The results of this study suggest that the overexpression of miR-16 inhibits the proliferation, invasion and metastasis of HepG2 HCC cells, and that these effects are associated with the PI3K/Akt signaling pathway.