Role and mechanism of miR-4778-3p and its targets NR2C2 and Med19 in cervical cancer radioresistance.

The aim of this study was to investigate the effect of miR-4778-3p on the radiosensitivity of cervical cancer cells and to elucidate the underlying mechanism. Tissue samples were collected from eight patients with cervical cancer prior to chemoradiotherapy. MicroRNA chip analyses, RT-PCR, gene transfection, CCK8, wound healing and Transwell assays, colony-forming assay, western blot, and the Dual-Luciferase Reporter Assay System were used to evaluate the role of miR-4778-3p in cervical cancer radiosensitivity and its relationships with target molecules NR2C2 and Med19. Thirty-two differentially expressed miRNA molecules (fold-change > 2; p < 0.05) associated with cervical cancer radioresistance were identified. The expression of miR-4778-3p was significantly lower in recurrent or metastatic patients than in control subjects. In vitro studies using radioresistant HeLa and SiHa cervical cancer cell lines showed that miR-4778-3p upregulation significantly inhibited cell proliferation, invasiveness, and migration after irradiation. There was also a significant increase in apoptosis and a significant decrease in the proportion of cells at the G2/M phase. Further, miR-4778-3p upregulation led to increased expression of apoptosis-related molecules, such as Bax, Caspase-3, Caspase-8, and Caspase-9. Reporter gene assays showed that miR-4778-3p bound specifically to NR2C2 and Med19 and negatively regulated their expression. Thus, miR-4778-3p reduces the vitality, proliferation, and migration of radioresistant cervical cancer cells and may regulate the radiosensitivity of cervical cancer by targeting and regulating NR2C2 and Med19 expression.