NHEJ基因保守性缺陷与放射敏感性的关系研究

Study on relationship between conservation of NHEJ system and radiosensitivity

目的:研究DNA双链断裂非同源性末端连接系统(NHEJ)保守性与敏感性的关系,寻找NHEJ系统基因的关键突变与肿瘤放射敏感性的关系。方法:采用聚合酶链式反应和克隆技术测定CNE、SPC-A1和MCF-7肿瘤细胞株与DNA双链损伤修复有关的NHEJ系统各基因的功能区序列,梯度比较和分析它们的功能区变化,模拟和比较突变产物亲疏水性差异。结果:CNE细胞中,NHEJ系统的终极基因LigaseⅣ存在与放射敏感性相关的突变,其氨基酸替换:313aaHis→Arg、538aaGly→Arg、579aaLys→Arg和585aaAsn→Ser影响产物蛋白结构。结论:在放射敏感性与NHEJ系统基因保守性和功能关系方面,LigaseⅣ的突变影响较大,与肿瘤细胞DNA双链断裂损伤修复能力和肿瘤放疗疗效直接相关。

Objective： To investigate the relation between conservation and sensitivity of NHEJ system of broken DNA double strains, and to find relationship between critical mutations of NHEJ system and radiosensitivity of tumor cells. Methods： Polymerase chain reaction and cloning and sequencing technique were used to determine the sequences of NHEJ＇s genes in CNE, SPC-1 AND MCF cell lines related with repair of DNA lesions in tumor cells, then gradient analyzed their conservative changes, and modulated and compared the protein productions and their hydrophicity-hydrophobicity related with these changes of NHEJ＇s genes. Results： LigaseⅣ gene of NHEJ system in CNE cells was found mutations related to radiosensitivity, which occurred substitution of amino acids including 313aa His→Arg, 538aa Gly→Arg, 579aa Lys→Arg and 585 aa Asn→Ser, and thus resulted in structural alteration of associated proteins. Conclusion ： In the relationship between the conservation and function of NHEJ system and radiosensitivity, Ligase Ⅳ＇s mutations are critical, which related directly to the repair ability of DNA double strains lesions , and thus impact the outcome of radiosensitivity and radiotherapy of human tumors.