α-粒子诱发人BEP2D恶性转化细胞的亚克隆及DNA链断裂修复研究

SUB-CLONING OF MALIGNANT TRANSFORMANTS OF BEP2D INDUCED BY α-PARTICLES AND THEIR CAPACITY OF REJOINING DNA DOUBLE-STRAND BREAKS

目的 :建立α 粒子诱发人支气管上皮细胞 (BEP2D)恶性转化细胞的克隆细胞系 ,研究其核型和DNA链断裂修复能力。方法 :1.5Gyα 粒子照射的BEP2D细胞传 35代后接种裸鼠成瘤 ,取出瘤细胞进行亚克隆 ,挑出单个克隆扩大培养 ,G带显示分析细胞核型 ,脉冲电场凝胶电泳法检测DNA双链断裂。结果 :亚克隆了 5个恶性转化细胞系 (RP35T 1, 2 , 4 , 5 , 6 ) ,核型基本与BEP2D细胞相近 ,但有着不同的染色体缺失 ,其中 2株细胞 (RP35T 2和RP35T 4 )多倍体高达 40 %,明显高于BEP2D细胞。恶性转化细胞RP35T 1和RP35T 4的DNA双链断裂重接修复缺陷。结论 :建立了α 粒子诱发人BEP2D恶性转化细胞的克隆细胞系 ,DNA链断裂修复缺陷可能是α 粒子致癌的一个重要特点。

Purpose: To subclone the malignant transformants of human bronchial epithelial cell line (BEP2D) induced by α-particles and to analyse their karyotypes and capacity of rejoining DNA double-strand breaks(DSB). Methods: Tumor cells were isolated from nude mice bearing malignant transformed cells(passage 35 cells of 1.5 Gy of α-particles-irradiated BEP2D and were subcloned in vitro. Trypsin/Giemsa banding of chromosomes and pulsed field gel electrophoresis were used to analyse karyotypes and DNA repair respectively. Results: Five individual malignant transformed cell lines(RP35T-1,-2,-4,-5,-6) were subcloned. Multi-locus chromosome deletions were shown in these malignant transformed cell lines as well as the parental line BEP2D. The ratio of polyploids of RP35T-2 and RP35T-4 cells was about 40% and was higher than that of PEB2D cells(5%), The other three lines showed the same polyploid levels as the parental cell line. The capacity of rejoining DSB in RP35T-1 and RP35T-4 cell lines was obviously deficient. Conclusion: Five malignant transformed cell lines were subcloned. The deficiency of DNA DSB repair could be an important characteristic of α-particle-induced carcinogenesis.