miR-639 is associated with advanced cancer stages and promotes proliferation and migration of nasopharyngeal carcinoma

Early detection of nasopharyngeal carcinoma (NPC) is of vital importance for improving prognosis and survival rates. MicroRNA (miRNA) are a class of short and non-coding RNA molecules that are capable of inhibiting the translation of mRNA of target genes. Previous studies have revealed that miRNA are involved in tumorigenesis and cancer development. The RNase-resistance of circulating miRNA have made them valuable non-invasive biomarkers, and has therefore drawn particular attention to their therapeutic potential. The aim of the present study was to investigate the expression of the previously uncharacterized miR-639 in NPC. In a study population of 139 patients, higher expression of miR-639 was associated with metastasis, more advanced cancer stages, and lower disease-free survival rates. In vitro experiments involving transfection of human NPC C666-1 and NPC/HK1 cell lines with miR-639 mimics and antagomir indicated that overexpressing miR-639 promoted cell proliferation and migration, suppression of miR-639 inhibited proliferation and migration. The present study provides evidence that miR-639 is differentially expressed in NPC tissues of varying cancer stages, and suggests that quantifying circulating miR-639 may be of importance for non-invasive diagnosis and prognostic evaluation, and may have potential therapeutic utility.