鼻咽癌、肺腺癌和乳腺腺癌细胞XRCC4基因保守性研究

The study on the homology of XRCC4 gene in CNE,SPC-A1 and MCF-7 cell lines.

目的 研究不同人类肿瘤细胞 XRCC4基因的保守性 ,探讨其与肿瘤放射敏感性的关系。方法 常规集落形成方法测定人类肿瘤鼻咽鳞癌 (CNE)、肺腺癌 (SPC- A1)和乳腺腺癌 (MCF- 7)不同剂量照射后的细胞存活率 ,采用聚合酶链式反应和克隆技术测定三种细胞 XRCC4基因序列 ,分析它们的保守性变化和突变对基因产物亲疏水性的影响。结果 三种细胞存活参数比较存在较大差异 ,CNE细胞较 SPC- A1和 MCF- 7细胞显示出较高的放射敏感性。CNE、 SPC- A1和 MCF- 7细胞 XRCC4基因同源性分别为 :99.94 %、 99.97%和 99% ,存在包括碱基插入、缺失和颠换等突变形式。其中 ,CNE和 MCF- 7细胞 6 bp的 TTCTAG插入突变导致的氨基酸序列变化影响该基因产物的亲疏水结构。结论 XRCC4基因产物在非同源性末端连接途径中起重要的协调作用 ,CNE和 MCF- 7细胞该基因的同源性低于 SPC- A1细胞 ,两者的 6 bp插入突变是影响肿瘤细胞 DNA双链断裂损伤修复能力和肿瘤放射敏感性的因素之一。

Objective To investigate the conservation of XRCC4 gene in CNE,SPC A1 and MCF 7 cell lines and discuss the relationship between this conservation and the radiosensitivity for human tumor cells.Mathods A nasopharyngeal(CNE)?a lung adenocarcinoma(SPC A1) and a breast adenocarcinoma(MCF 7) cell lines were used to assess for cell survival parameter after radiations,Polymerase chain response and cloning and sequencing technique were applied to determine the sequence of XRCC4 gene in three cell lines,then analyzing their conservative changes and mutations resulting in outcomes of these products.Results The survival fractions of three cell lines were different,it suggest that CNE cell line were more radiosensitive than SPC A1 and MCF 7 cell lines.In CNE,SPC A1 and MCF 7 cell lines,the homology of XRCC4 gene were:99 94%,99 97% and 99%,respectively,mutations including insertion and transition,6bp insertions(TTCTAG) lead to altering amino acid by others and changing the hydrophicityhydrophobicity of these products in CNE and SPC A1 cell lines.Conclusions The conservations of encoding regions of XRCC4 gene of nonhomologous DNA end joining pathway in CNE and MCF 7 cell lines are lower than in SPC A1 cell line.Therefore,mutations of 6bp insertions may is one of changing ability of repairing double strand breaks and the outcome of radiotherapy for human tumor.