MicroRNA-378g enhanced radiosensitivity of NPC cells partially by targeting protein tyrosine phosphatase SHP-1.

Purpose: To investigate the influence of microRNA-378g (miR-378g) on radiosensitivity and metastasis of nasopharyngeal carcinoma cells and study how miR-378g regulated Src homology region 2 domain-containing phosphatase-1 (SHP-1) expression.

Materials And Methods: Polymerase chain reaction (PCR) was used to detect the expression level of miR-378g and SHP-1 mRNA in different nasopharyngeal carcinoma (NPC) cell lines. MiR-378g mimics were transfected into NPC cells and radiosensitivity was determined by colony formation assay. Cell apoptotic rate was determined by flow cytometry analysis. Cell invasion was examined by transwell assay. SHP-1 transcriptional activity was examined by luciferase assay. SHP-1 expression level was determined by Western blot. Lentivirus containing SHP-1 gene and miR-378g mimics were co-transfected into NPC cells and radiosensitivity and metastasis were detected by colony formation assay and transwell assay again.

Results: Expression of miR-378g and SHP-1 mRNA was negatively correlated in NPC cell lines. MiR-378g mimics enhanced radiosensitivity, promoted apoptosis and decreased invasion in NPC cells. SHP-1 expression was inhibited by miR-378g mimics. Luciferase reporter assay showed that miR-378g directly targeted SHP-1 by binding to 3' untranslated region (3'UTR) of SHP-1 mRNA. Overexpression of SHP-1 partially inversed the effect of miR-378g mimics on radiosensitivity, but had no effect on cell invasion.

Conclusion: MiR-378g enhanced radiosensitivity partially by targeting SHP-1 in NPC cells. Cell invasion was also partially inhibited by miR-378g, but the effect was not mediated by SHP-1.