miRNA expression profile of vulvar squamous cell carcinoma and identification of the oncogenic role of miR-590-5p.

MicroRNAs (miRNAs), a class of small non-coding RNA molecules, are associated with a variety of human cancers. Currently, little data are available regarding miRNA expression in vulvar squamous cell carcinoma (VSCC); the mechanism of action of miRNAs in VSCC still requires investigation. The aim of the present study was to investigate the miRNA expression profile in VSCC using a miRCURY™ LNA array. The expression levels of selected miRNAs were quantified by RT-qPCR. The relationship between miR-590-5p expression and clinical pathology was assessed. The expression levels of crucial transforming growth factor-β (TGF-β) and Smad pathway factors were detected. We further investigated the role of miR-590-5p via in vitro studies in the A431 human VSCC cell line. A total of 157 miRNAs showed significantly altered expression in this type of carcinoma. Of particular interest, miR-590-5p, miR-182-5p and miR-183-5p were upregulated, and miR-603, miR-103a-3p and miR-107 were downregulated. A positive relationship was found between miR-590-5p expression and lymph node metastasis. In VSCC, TGFβ1 and TGFβ2 were significantly overexpressed and TGFβRII and Smad4 were significantly underexpressed at both the RNA and protein levels. In A431 cells, overexpression of miR-590-5p promoted proliferation, migration and G1-S phase transition and downregulated TGFβRII. The knockdown of TGFβRII by siRNA promoted malignant behaviours in the A431 cells. In conclusion, we present the miRNA expression profile in VSCC, and our findings suggest that the upregulation of miR-590-5p promotes cellular malignant behaviours via the target gene TGFβRII.