目的：探索抑制Polo样激酶1（Polo-like kinase 1，PLK1）对鼻咽癌（nasopharyngeal carcinoma，NPC）细胞CNE-1和CNE-2辐射敏感性的影响。方法：分别运用siRNA和小分子抑制剂BI2536抑制CNE-1和CNE-2细胞内PLK1的表达或磷酸化，通过MTT法检测抑制PLK1对NPC细胞增殖能力的影响，流式细胞技术检测对细胞周期和凋亡的影响，细胞免疫荧光检测对辐射后DNA损伤位点的影响，克隆形成实验及曲线拟合计算对辐射后细胞放射生物参数和放射增敏比（sensitization enhancement ratio，SER）的影响。结果：与对照组相比，抑制PLK1可以明显抑制NPC细胞增殖，并诱导细胞发生G2-M期阻滞和有丝分裂灾难。抑制NPC细胞PLK1联合射线辐射后，NPC细胞克隆形成能力下降（CNE-1：P<0.05；CNE-2:P<0.05），且随着BI2536浓度的增大克隆形成能力下降更加明显（CNE-1：P<0.05；CNE-2:P<0.05）；细胞生存分数明显降低（均P<005）；核中γ-H2AX位点数目明显增加（P<0.05）；细胞凋亡率显著升高（均P<0.05）；siR-PLK1转染CNE-1和CNE-2后SER分别为1.1988和1.3198，BI2536处理CNE-1和CNE-2后SER分别为1.5508和1.2028。结论：抑制PLK1可以抑制NPC细胞增殖，诱导发生细胞周期阻滞和有丝分裂灾难，并能显著提高NPC细胞辐射敏感性。

Objective:To explore effect of inhibiting Polo-like kinase 1 (PLK1) on radiosensitivity of nasopharyngeal carcinoma (NPC) CNE-1 and CNE-2 cell lines. Methods: Using small interfering RNA (siRNA) and small molecule inhibitor BI2536 to inhibit expression and phosphorylation of PLK1 in the CNE-1 and CNE-2 cells respectively. Effect of inhibiting PLK1 on proliferation ability of the NPC cells was tested by MTT assay. Flow cytometry assay was used to detect effect of the inhibition on cell cycle and apoptosis of the NPC cells and immuno fluorescence assay was used to assess the effect of damage sites of DNA in the NPC cells after radiation. Clone formation experiment and curve fitting assay were used to calculate radiation parameters and sensitization enhancement radio (SER) of the NPC cells after radiation. Results: Compared with the control group, inhibition of PLK1 in the NPC cells reduced proliferation of the NPC cells and, induced G2-M arrest and mitotic catastrophe of the NPC cells. Inhibition of PLK1 in the NPC cells combined with irradiation significantly decreased ability of cell colony formation in the NPC cells (CNE-1:P<0.05, CNE-2:P<0.05), and with increasing concentration of the B12536, the ability of cell colony formation in the NPC more pronounced declined (CNE-1:P<0.05, CNE-2:P<0.05). In addition, Inhibition of PLK1 in the NPC cells combined with irradiation reduced the cell survival fraction, increased the number of γ-H2AX loci in nucleus of the cells, and accelerated apoptosis rate of the cells obviously (all P<0.05). SER of the CNE-1 and the CEN2 cells were 1.1988 and 1.3198 respectively after transfection of them with siR-PLK1. And SER of the CNE-1 and the CEN-2 cells were 1.5508 and 1.2028 respectively after treatment of them with the B12536. After treatment of the CEN-1 and the CEN-2 cells with the B12536. Conclusion: Inhibition of PLK1 could suppress infiltration of the NPC cells, induce cell-cycle arrest and mitotic catastrophe, and significantly enhance radiosensitivity of the NPC cells.

国家自然科学基金资助项目（No. 81572964,No.81274508）;广东省自然科学基金资助项目（No.2014A030313289）;广东省教育厅科研资助项目（No.2013KJCX0038）