电离辐射诱导骨肉瘤细胞DNA损伤修复蛋白APE1线粒体定位研究

Mitochondrial translocation of DNA damage and repair protein APE1 in human osteosarcoma cell after ionizing radiation

目的探讨电离辐射诱导骨肉瘤细胞脱嘌呤／脱嘧啶核酸内切酶（apurinic／aprimidinic endonuclease 1，APE1）线粒体定位表达情况，为进一步研究线粒体DNA修复在骨肉瘤放射治疗抵抗中的作用提供依据。方法应用激光共聚焦显微术和Western blot观察正常对照组和12Gy X线照射后不同时相点骨肉瘤细胞株HOS细胞中APE1线粒体定位情况。结果对照组、12Gy X射线处理后1、2、3h APE1和线粒体有共定位现象，APE1细细胞质／细胞核荧光强度比值分别为：（0．78±0．04）、（1．04±0．03）、（1．14±0．05）、（1．80±0．38）。Western blot亦证实线粒体内APE1蛋白表达增高。结论放射后早期APE1向细胞质线粒体移位，从1～3h逐渐增高，提示APE1可能在电离辐射后骨肉瘤细胞线粒体DNA损伤修复中发挥重要作用。

Objective To investigate mitochondrial localization of apurinic/aprimidinic endonuclease/redox factor-1 （APE1） in human osteosarcoma cells after ionizing radiation （IR）, shedding light on further study of the role of mitochondrial DNA repair in resistance to radiotherapy for osteosarcoma. Methods The mitochondrial localization of APE1 in untreated human osteoblast sarcoma （HOS） cells and HOS cells exposed to 12 Gy X-ray was observed by laser confocal microscopy, then confirmed by Western blot. Results APE1 in untreated HOS cells and HOS cells exposed to 12 Gy X-ray for 1,2, 3 h could translocate to mitochondria, and the cytoplasm/nucleus fluorescent intensity values were （0.78±0.04）, （ 1.04±0.03 ）, （ 1.14±0.05 ）, （ 1.80±0.38 ）, respectively. Mitochondrial APE1 protein increasing in time course was also confirmed by Western blot. Conclusion APE1 can shift from nuclus to mitochondria at early stage after IR treatment, and increase within time-course, suggesting APE1 may play a crucial role in mitochondrial DNA repair of osteosarcoma cells after IR.