目的：探究miR-145影响鼻咽癌细胞增殖可能的机制。方法：采用Real-time PCR法检测鼻咽癌细胞株CNE-1、CNE-2、CNE-2Z和鼻咽部永生化上皮细胞株NP69中miR-145和c-Myc的mRNA表达水平，Western blotting法检测c-Myc的蛋白表达水平，双萤光素酶报告基因实验检测miR-145与基因c-Myc的关系。分别将miR-Negative control、miR-145 mimics和si-NC、si-c-Myc转染进入CNE-1细胞，采用Real-time PCR及Western blotting法检测转染效果，CCK-8法检测转染后细胞的增殖情况，以及碘化丙啶（IP）染色流式细胞术检测细胞周期情况。结果： miR-145在鼻咽癌细胞系中明显低表达。转染miR-145后明显抑制CNE-1细胞的增殖\[3 d: （1.03±0.02） vs （1.21 ± 0.02）, P<0.05\]；\[ 4 d: （1.79±0.02） vs （2.09±0.07）, P<0.01\]和导致G1期阻滞\[（79.57±1.47）% vs （69.98±1.16）%，P<0.05\]。miR-145可以直接作用于c-Myc的3’UTR区域，抑制c-Myc的转录和表达。c-Myc下调可明显抑制CNE-1细胞的增殖\[3 d: （0.80±0.02） vs （1.02±0.01）, P<0.01\]；\[4 d: （1.68±0.4） vs （1.92±0.07）, P<0.01\]，并致G1期阻滞\[（63.73± 1.81）% vs （54.10±2.26）%，P<0.05\]。结论： miR-145通过靶向作用于c-Myc的3’UTR区来抑制鼻咽癌细胞的增殖，对更深入探索鼻咽癌的诊断和治疗有着重要意义。

Objective:The aim of this study was to investigate the possible mechanisms underlying the effect of miR-145 on the proliferation in nasopharyngeal carcinoma (NPC) cells.Methods: Protein and mRNA levels of miR-145 and c-Myc mRNA and protein were determined in 3 NPC cell lines (CNE-1, CNE-2 and CNE-2Z) and one immortalised nasopharyngeal epithelial cell line (NP69) by Western blotting and Real-time PCR respectively. To evaluate the effect of miR-145 on c-Myc transcript and proliferation in NPCs, CNE-1 cells were transfected with microRNA mimics and small interfering RNA using LipofectamineTM 2000. Transfectants were subjected to proliferative activity assessment using Cell Counting Kit-8 assay and cell cycle arrest analysis by propyliodide organism (PI) staining.Results: The expression of miR-145 in was down regulated but c-Myc expression was up-regulated in all NPC cell lines studied as compared with NP69 cells. After Transfection of miR-145 mimics resulted in significant growth-suppression(P<0.01) and a significant increase in cell cycle arrest in G1 phase (P<0.05). Knock down of c-Myc significantly inhibited CNE-1 cell proliferation (P<001), and resulted in increased accumulation of CNE-1 cells in G1 phase (P<0.05). Furthermore, miR-145 inhibited c-Myc expression in CNE-1 cells by directly affecting the 3’ untranslated region (3' UTR) of the c-Myc gene. Conclusion: miR-145 may inhibit NPC cell proliferation, possibly through a direct effect on the c-Myc 3’ UTR region. This observation may have significant implications in the diagnose and treatment of NPC.

江苏省高校自然科学基金资助项目（No. 14KJB310017）；苏州市国际科技合作计划国际技术引进与合作创新基金资助项目（No. SH201209）