MiR-224-5p Targeting OCLN Promotes the Proliferation, Migration, and Invasion of Clear Cell Renal Cell Carcinoma Cells

A number of studies reported that miR-224-5p is involved in a variety of cancer-related cellular processes, yet its physiological role in clear cell renal cell carcinoma (ccRCC) remains unclear. In order to clarify the function of miR-224-5p in ccRCC, real-time quantitative-PCR was conducted to compare the expression of miR-224-5p in human normal renal tubular epithelial cell lines and ccRCC cell lines first, and a strikingly upregulated expression was observed in ccRCC cell lines. Inhibition of miR-224-5p expression by microRNA inhibitors could inhibit the proliferation, migration, and invasion of ccRCC cells. Besides, it was validated by dual-luciferase assay in which miR-224-5p directly targeted OCLN gene. The expression of OCLN was downregulated in ccRCC cells, and overexpression of miR-224-5p could inhibit the mRNA and protein expression levels of OCLN. Overexpression of OCLN could reduce the proliferation, migration, and invasion of ccRCC cells, while overexpressed miR-224-5p could partially reverse that inhibitory effect. Therefore, the promotive effect of miR-224-5p on the proliferation, invasion, and migration of ccRCC cell lines was at least partly due to the inhibition of OCLN expression. These findings highlighted the important function of miR-224-5p, which was promoting cell proliferation, migration, and invasion by downregulating OCLN, in the pathogenesis of ccRCC, and provided a potential treatment strategy.