ObjectiveTo investigate the clinical significance of microRNA375(miR375) expression in nasopharyngeal carcinoma (NPC) and its impact on NPC cells.Methods67 NPC specimens and 53 chronic pharyngitis specimens were collected. Realtime fluorescence quantitative polymerase chain reaction (qRTPCR) was used to detect the expression of miR375 in the specimens, CNE1, CNE2, C6661 and NP69 (an immortalized nasopharyngeal epithelial cells line) cells lines. All the cells were transfected with miR375 mimics or inhibitors respectively. Cell proliferation was detected by CCK8 assay kit and cell migration by transwell assay. Bioinformatics software was adopted to predict the target gene of miR375, and the expression of the target gene was verified by Western blot and dual luciferase assay.ResultsThe expression of miR375 in NPC specimens was markedly downregulated compared to that in the chronic pharyngitis tissues (P<0.05). The expression level of miR375 was correlated with the size, lymph node metastasis and clinic stage of tumor (all P<0.05), but had no correlation with the patients' age, gender and smoking history, histologic type and differentiation degree of the tumor (all P>0.05). The expression levels of miR375 in the 4 types of NPC cells were significantly lower than that in the NP69 cell (all P<0.05). After overexpression of miR375, proliferation and migration abilities of C6661 cell were significantly lower than those of the chronic pharyngitis tissues (both P<0.05), and NLK expression was downregulated. After suppression of miR375, the abilities of CNE1 cell were significantly higher than those of the chronic pharyngitis tissues (both P<0.05), and NLK expression was upregulated. The miR375 targeted regulation on the NLK directly.ConclusionThe expression of miR375 is downregulated in NPC, which is correlated with the size, regional lymph node involvement and clinic stage of the tumor. miR375 may inhibit the proliferation and migration of NPC cells by downregulating its target NLK gene.