环磷酰胺诱导永生化人支气管上皮细胞恶性转化过程中的基因突变

Gene mutation in the oncogenic transformation process of immortalized human bronchial epithelial cells induced by cyclophosphamide

环磷酰胺 (CP)是国际癌症研究署确认的人类I组致癌原 ,目前缺乏适宜的人类细胞模型开展致癌相关的细胞和分子机理的研究 .本室已经进行了CP诱导永生化人支气管上皮细胞 (BEAS 2B)恶性转化的工作 ,建立了CP的癌前转化细胞 (BEAS CP) ,以此为细胞模型 ,本实验运用聚合酶链式反应单链构象多态性和序列分析的方法进行了细胞转化进程中基因突变的动态分析 .分别关注了p5 3基因第5～ 8,p16基因第 1～ 2和ki ras基因第 1外显子的突变情况 .研究结果表明 :BEAS CP细胞存在p16基因第 1外显子多位点和ras基因第 1外显子单位点的碱基突变 ,晚代龄的转化细胞没有测到p5 3基因的突变 .综上实验结果认为 :p16基因突变可能与BEAS CP细胞周期的增殖性改变有关 ,ki ras基因的突变则可能具有转化启动效应 。

Previous paper has described the neoplastic transformation of immortalized nontumorigenic human bronchial epithelial cells(BEAS 2B) induced by cyclophosphamide(CP, BEAS CP). Oncogene and tumor suppressor gene mutations are known to associate with cell transformation. In order to investigate gene alterations of BEAS CP cells, using the established transformation model consisted of BEAS 2B and BEAS CP cells, analysis of p53, p16 and ki ras genes mutations were made. The results were revealed as follows: detection of p16 mutation disclosed an A→G transition at the 70th nucleotide. A single G and A deletion occurred at the 75th and the 78th nucleotides of non codon region adjacent to exon 1, respectively. Analysis of ki ras gene showing a CAG→GAG transversion at codon 25 causes a glutamine to glutamic acid exchange. These results hinted that p16 gene mutations may play an important role in the BEAS 2B cell cycle alterations and the ki ras mutation may have the transformation initiation effect. A mixed role for p16 and ki ras mutations in CP mediated carcinogenesis therefore can be confirmed.