Abstract: Objective　To investigate the effect of miR-146a on cisplatin sensitivity of nasopharyngeal carcinoma HNE-1 / DDP cells and its possible mechanism.　Methods　The experiment was divided into three groups: a blank control group, a negative control group and a mimics-miR-146a group. MTT assay was used to detect the proliferation inhibition of cells after different treatments. Annexin V-FITC / PI assay was used to detect apoptosis. Western blot was used to detect the relative expression levels of cyclin CCNJ, MRP1, P-gp. RT-qPCR was used to detect the relative expression level of CCNJ mRNA.　Results  Compared with other two groups, the survival rate, the relative protein expression levels of MRP1, P-gp, CCNJ and the relative expression level of CCNJ mRNA of mimics-miR-146a reduced, while the apoptosis rate increased. There were statistical differences in the survival rate, the relative protein expression levels of MRP1, P-gp, CCNJ, the relative expression level of CCNJ mRNA and the apoptosis rate among the three groups (P<0.05).　Conclusions　miR-146a can increase the sensitivity of HNE-1/DDP to DDP which mechanism may be through miR-146a inhibiting the expression of CCNJ to regulate downstream proteins MRP1,P-gp,and then to reduce cell resistance.

Key words: Nasopharyngeal carcinoma, 　Drug resistance, 　Micro RNA, 　Cisplatin, 　Cyclin protein