miR-331-3p Inhibits Proliferation and Promotes Apoptosis of Nasopharyngeal Carcinoma Cells by Targeting elf4B-PI3K-AKT Pathway.

Background: The incidence of nasopharyngeal carcinoma is increasing gradually, but the pathogenesis is not completely clear. MicroRNA, a highly conserved endogenous noncoding small molecule RNA, plays an essential role in the regulation of gene expression and is a hotspot in cancer research worldwide. Objectives: Although previous studies have confirmed that the abnormal expression of microRNAs is closely related to the progression of nasopharyngeal carcinoma, the role of miRNA-331-3p in nasopharyngeal carcinoma has not been studied. The purpose of this study was to explore the role and mechanism of miRNA-331-3p in the progression of nasopharyngeal carcinoma. Materials and Methods: Real-time quantitative reverse transcription polymerase chain reaction was performed to detect the expression of miRNA-331-3p in nasopharyngeal carcinoma clinical samples and cell lines (CNE-1 and 5-8F cells). After overexpression of miRNA-331-3p in CNE-1 cells, cell proliferation was measured by Cell Counting Kit-8 assay, cell invasion was detected by Transwell assay, and apoptosis was tested by flow cytometry. In addition, the dual-luciferase reporter assay was used to identify the target gene of miRNA-331-3p and Western blotting was performed to measure the relative protein expression. Results: The expression of miRNA-331-3p in nasopharyngeal carcinoma clinical samples and cells was decreased significantly. Overexpression of miRNA-331-3p markedly inhibited the proliferation and invasion of CNE-1 cells and promoted cell apoptosis. Moreover, overexpression of miRNA-331-3p reduced the expression of target gene elF4B, leading to inhibition of the phosphorylation of Phosphoinositide 3-kinase (PI3K) and Serine/ threonine kinase (AKT). Conclusion: miRNA-331-3p inhibited cell proliferation and induced cell apoptosis in nasopharyngeal carcinoma by targeting elF4B gene and then blocked the PI3K-AKT signaling pathway.