Zhuang Liang, Liu Fei, Peng Ping, Xiong Huihua, Qiu Hong, Fu Xiugen, Xiao Zhiping, Huang Xiaoyuan
Cancer Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.
Oncol Lett. 2018 Jan;15(1):147-154. doi: 10.3892/ol.2017.7304. Epub 2017 Oct 31.
Cisplatin chemotherapy in combination with radiotherapy is the primary therapeutic strategy for the treatment of cervical cancer; however, the underlying molecular mechanism for cisplatin radiosensitization remains unknown. The aim of the present study was to investigate the effect of Ku80, a DNA double-strand break (DSB) repair protein, on cisplatin radiosensitization in cervical cancer. The pre-established Ku80 suppression cervical cancer cell line HeLa/Ku80-siRNA and the normal HeLa cell line underwent 6 MV X-ray irradiation (6 Gy) individually or in combination with 5 µg/ml cisplatin treatment. Alterations in apoptosis, the cell cycle and γH2AX expression were detected. Following irradiation individually and combined with cisplatin, compared with normal HeLa cells, HeLa/Ku80-siRNAexhibited an increased rate of apoptosis (P<0.05). It was identified that the earlier cisplatin was administered following irradiation, the higher the rate of apoptosis. Cell cycle analysis indicated that, following irradiation combined with cisplatin, the cells were arrested in G and S phase rather than in G/M phase following irradiation alone. Microscopic imaging of immunofluorescence staining and western blotting identified that HeLa/Ku80-siRNA cells exhibited more γH2AX foci remaining following treatment with irradiation and cisplatin, particularly in the group treated with 6 Gy irradiation for 1 h together with 23 h of exposure to cisplatin. Irradiation in combination with cisplatin promoted the apoptosis of HeLa cells in association with the inhibition of Ku80, and it was identified that the earlier cisplatin was administered following irradiation, the more apoptosis was induced. This maybe because irradiation combined with cisplatin is able to arrest cells in G and S phase to rapidly repair damaged DNA, and the lack of Ku80 induces the inability to repair DSB, resulting in increased apoptosis. The results of the present study suggest that Ku80 may be a potent molecular target in cisplatin radiosensitization.
顺铂化疗联合放疗是治疗宫颈癌的主要治疗策略；然而，顺铂放射增敏的潜在分子机制仍不清楚。本研究的目的是探讨DNA双链断裂（DSB）修复蛋白Ku80对宫颈癌顺铂放射增敏的影响。预先建立的Ku80抑制性宫颈癌细胞系HeLa/Ku80-siRNA和正常HeLa细胞系分别接受6 MV X射线照射（6 Gy）或联合5 μg/ml顺铂处理。检测细胞凋亡、细胞周期和γH2AX表达的变化。单独照射和顺铂联合照射后，与正常HeLa细胞相比，HeLa/Ku80-siRNA细胞凋亡率增加（P<0.05）。结果表明，照射后越早给予顺铂，凋亡率越高。细胞周期分析表明，顺铂联合照射后，细胞停滞在G期和S期，而不是单独照射后的G/M期。免疫荧光染色和蛋白质印迹的显微镜成像显示，HeLa/Ku80-siRNA细胞在照射和顺铂处理后残留更多的γH2AX灶，特别是在6 Gy照射1 h并暴露于顺铂23 h的处理组中。顺铂联合照射促进HeLa细胞凋亡与Ku80的抑制有关，并且发现照射后越早给予顺铂，诱导的凋亡越多。这可能是因为顺铂联合照射能够使细胞停滞在G期和S期以快速修复受损DNA，而Ku80的缺失导致无法修复DSB，从而导致凋亡增加。本研究结果表明，Ku80可能是顺铂放射增敏的有效分子靶点。
