中文摘要：

目的应用pSilence APE1“敲低”HOS细胞APE1的表达，观察pSilence APE1联合中子放疗对HOS细胞生长抑制的协同作用并探讨其机制。方法用脂质体将pSilence APEI质粒导人HOS细胞，“敲低”HOS细胞中APE1的表达，同时给予^252Cf中子射线照射，MTT法绘出细胞存活曲线，克隆形成分析测算D37值和剂量修饰系数（DMF），彗星分析法检测照射后细胞的DNA损伤情况，并用流式细胞仪检测细胞凋亡。结果由克隆形成分析得到对照质粒与转染pSilence APE1质粒的HOS细胞经^257Cf中子照射后的D37值为3．02和2．42，DMF值为1．43。以上2组HOS细胞以200、500和1000cGy3个剂量^252Cf子射线照射后，碱性彗星尾力矩分别是6．146±0．741、19．918±1．574、31．885±1．192和7．997±0．542、25．238±1．185、39．191±1．052（P〈0．01）；细胞凋亡率是4．00、5．91、9．63和5．68、7．55、13．51（P〈0．05）。结论pSilence APE1能显著提高HOS细胞对中子射线的敏感性，促进DNA损伤和细胞凋亡。pSilence APE1基因联合中子放疗可能成为今后骨肉瘤治疗的新方法。

英文摘要：

Objective To knock down APE1 gene expression in HOS cells, and explore its antitumor effects in combination with ^252Cf neutron radiotherapy. Methods pSilence APE1 siRNA plasmid was transfected into HOS cells by SuperFect Transfection liposome. The transfected HOS cells were irradiated by 252 Cf neutron, then MTT assay, clone formation assay and alkaline comet assay were used to detect the radiobiological reaction, and cell apoptosis was detected with flow cytometry. Results The D37 value was 3.02 vs. 2.42 in the control and transfected HOS cells respectively after irradiation with 252 Cf neutron, the DMF value is 1.43. The tail moments and cell apoptosis rate at 200, 500 and 1000 cGy showed significant difference between the two groups （ P 〈 0.05）. Conclusions pSilence APE1 may significantly sensitize the neutron radiotherapy of the HOS cells, and enhance DNA damage and cell apoptosis. Therefore, the gene therapy with pSilence APE1 combined 252 Cf neutron radiotherapy may be a promising approach to therapy of human osteosarcoma in the future.