miR-210 regulates esophageal cancer cell proliferation by inducing G2/M phase cell cycle arrest through targeting PLK1

micro (mi)RNAs are short regulatory RNAs that negatively modulate protein expression at the post-transcriptional level, and are being considered as novel therapeutic targets for the treatment of cancer. In the present study, an elevated expression level of circulating miR-210 was observed in patients with esophageal squamous cell carcinoma (ESCC) for the first time, to the best of our knowledge, and the induction of miR-210 under hypoxic conditions in ESCC was confirmed. Cell counting kit-8 assay and bromodeoxyuridine incorporation assay indicated that miR-210 markedly inhibited the proliferation of ESCC cells. In addition, the effect of miR-210 on the cell cycle was examined. Transfection of miR-210 resulted in a significant increase in the proportion of cells in G(2)/M phase. Polo-like kinase 1 (PLK1) was investigated as a candidate target of miR-210, which is a critical regulator. of cell cycle transmission at multiple levels. It was demonstrated that miR-210 reduced the levels of PLK1 protein by binding the 3' untranslated region of its mRNA. The results of the present study demonstrated that miR-210 inhibited the proliferation of ESCC cells by inducing G2/M phase cell cycle arrest, and these effects of miR-210 were mediated by the targeting of PLK1.