miR-4270 Modulates the Irradiation-Sensitivity of Nasopharyngeal Carcinoma Cells through Modulation of p53 in Vivo

The lowered sensitivity to irradiation considerably impacted on the prognosis of nasopharyngeal carcinoma treatments. This study aimed to explore the functions of miR-4270 in nasopharyngeal carcinoma. Bioinformatic analysis was performed online accessing GSE139164 dataset to screen the top 30 differential microRNAs in nasopharyngeal carcinoma patients with radio-sensitivity. Cancer cell lines, 6-10B and 5-8F, were cultured and measured for expression of miR-4270 and TP53 (the gene of the tumor suppressor protein p53) with the normal nasopharyngeal epithelial cells as a control. The miR-4270 expression was regulated in cells via the introduction of miR-4270 inhibitor or mimic in different concentrations (25, 50, 100 nmol/L). Targetscan predicted the target of miR-4270 and the bindings while luciferase was used to confirm this. CCK8 methods were used to evaluate the irradiation sensitivity of the cells after exposure to increasing X-Ray irradiation. RT-PCR detected the RNA expression and Western blot examined the protein expression of p53. Flow cytometry detected the cell apoptosis rates respectively. miR-4270 is among the top differential microRNAs between the radio-sensitive and -resistant patients. In vivo, miR-4270 expression was lower in cancer cell lines. The inhibition of miR-4270 raised the cell sensitivity to irradiation. miR-4270 negatively mediated TP53 and targeted TP53. Additionally, p53 increased cell sensitivity to irradiation and modulated by miR-4270 in nasopharyngeal carcinoma cells. In conclusion, this study first reports that miR-4270 is lower in the radio-sensitive patients and modulated the irradiation-sensitivity of nasopharyngeal carcinoma cells through modulation of p53 in vivo.