miR-4295 promotes epithelial to mesenchymal transition and human nasopharyngeal carcinoma invasion by directly targeting PTEN

Objective To investigate the possible functions and mechanism of miR-4295 in metastasis of human nasopharyngeal carcinoma (NPC). Methods We tested the expression of miR-4295 in the NPC cell lines by reverse transcriptase polymerase chain reaction (QPCR); packing retrovirus of pMSCV-puro and pMSCV-miR-4295 to infect 5-8F cells to establish stable cell lines. We tested the invasion and migration ability of cells by Transwell invasion assay, wound healing assay, and 3-D culture. Western blot (WB) and QPCR were used to test the E-Cadherin, Fibronectin, and Vimentin expression between 5-8F/miR-4295 and 5-8F/vector at both mRNA and protein levels; luciferase activity report was used to verify the target of miRNA. Results We found the miR-4295 had obviously higher expression in 5-8F cell. Transwell invasion assay, wound healing assay, and 3-D culture in matrigel found that the migration and invasion ability of 5-8F were strongly promoted by stable overexpression of miR-4295. Western blot and QPCR analysis showed that the expression level of epithelial markers E-cadherin in 5-8F/miR-4295 was downregulated, while the expression of mesenchymal markers Fibronectin and Vimentin were upregulated. PTEN was identified by luciferase reporter as a direct target of miR-4295. Its expression was downregulated by miR-4295. Furthermore, the results showed that the expression of miR-4295 was inversely correlated with the expression of PTEN protein. Conclusion miR-4295 might promote epithelial to mesenchymal transition (EMT) and human nasopharyngeal carcinoma metastasis by PTEN in vitro. Key words: miR-4295; PTEN; Epithelial to mesenchymal transition (EMT); Nasopharyngeal carcinoma (NPC); Cell migration and invasion