辐射致大鼠平滑肌细胞HPRT基因第7/8外显子突变分析

目的探讨辐射剂量与平滑肌细胞HPRT基因变异的关系,提供放射预防血管再狭窄的基础实验依据.方法不同剂量的放射性核素188Re内辐射平滑肌细胞后,应用6-TG筛选分离HPRT变异细胞,采用PCR-SSCP技术进行HPRT基因7/8外显子的变异分析.结果辐射后平滑肌细胞HPRT基因突变率为(5.5～13)×10-6;91株HPRT突变细胞克隆中,14.3%呈现7/8外显子缺失,16.5%呈现点突变,7/8外显子总变异率为30.8%;辐射剂量与HPRT基因突变率、第7/8外显子的总变异率及外显子缺失率呈正相关.结论辐射所致DNA分子的损伤,包括基因片段的缺失、断裂及点突变与辐射剂量呈正相关.

Analysis of mutation induced by radiation in HPRT gene exon 7/8 of rat smooth muscles cells

Objective To investigate the relationship between radiation dose and HPRT gene locus mutation in rat smooth muscle cells,and provide a molecular basis for prevention of blood vessel restenosis after PTCA. Methods The smooth muscle cells cultured in vitro were irradiated by radionuclide ¹⁸⁸Re with different doses.HPRT gene mutation colonies were selected and isolated by 6-thioguanine.Analysis of mutation in exon 7/8 of HPRT gene were accomplished by polymerase chain reaction and single-strand conformation polymorphism. Results The HPRTgene mutation frequency of rat smooth muscle cells that were irradiated by radionuclide ¹⁸⁸Re ranged from 55×10^-6 to 13×10^-6. of 91 HPRT gene mutation colonies,13 contained exon 7/8 deletion and 15 had point mutation.The exon 7/8 mutation frequency was 308%.There was significant relationship between radiation dose and mutation frequency of HPRTgene and exon 7/8. Conclusions The DNA damage and gene mutation induced by radiation was the basis of proliferation inhibition and apoptosis of smooth muscle cells.