环磷酰胺诱导TK6细胞TK基因杂合性丢失的实验研究

Loss of Heterozygosity Induced by Cyclophosphamide at tk Locus in Human Lymphoblastoid Cell Line TK6

目的 应用人类淋巴母细胞TK6研究环磷酰胺(CP)遗传毒性分子机理。方法 CP+S9体外染毒TK6细胞4 h后检测细胞相对存活率、tk位点突变频率并进行TK基因缺失突变体杂合性丢失(L OH)的分析。结果 环磷酰胺染毒导致TK 6细胞相对存活率下降,TK基因突变频率上升,并呈现剂量-反应关系。正常及缓慢生长突变集落倍增时间分别为(14 .6±1.74 ) h及(35 .8±3.78) h。环磷酰胺诱导产生半合子L OH的比例(5 0 % )是对照(2 0 .7% )的2 .4倍。结论 环磷酰胺对TK基因较大范围的损伤是导致基因突变的主要原因。

Objective Human lymphoblastoid cell line TK6 was used to investigate TK gene mutation frequency and the loss of heterozygosity (LOH) induced by cyclophosphamide (CP). Methods Relative survival ,mutation frequency at tk locus induced by CP (+S9)after 4 h treatment were detected. DNA isolated from mutants in the control culture and CP treatment group was analyzed for LOH. Results Exposure to CP for 4 h decreased relative survival, induced TK gene mutation in a dose-dependent manner. Doubling time of normally and slowly growing mutants was (14.6±1.74) h and (35.8±3.78) h respectively. The percentage of hemizygous LOH in CP-induced mutants (50%) was 2.4 times than that of the control (20.7%). Conclusion Great damage to TK gene is the main cause of mutation induced by CP in TK6 cells.