MOLECULAR ANALYSIS OF RADIATION-INDUCED MUTATION IN EXON 7/8 OF RAT HPRT GENE

Objective To investigate the relationship between the radiation dose and the HPRT gene lo-cus mutation in rat smooth muscle cells, and provide the molecular basis for prevention of restenosis after percutaneous transluminal coronary angioplasty (PTC4). Methods The smooth muscle cells cultured in vitro were irradiated by radionuclide 188Re in different doses. HPRT gene mutation colonies were selected and isolatedby 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 HPRT gene mutation frequency of rat smooth muscle cells that were irradiated by radionuclide 188Re ranged from 5.5× 10-6 to 13 ×10-6. Of 91 HPRT gene mutation colonies, 13 (14.3%) contained exon 7/8 deletion and 15(16.5%) had point mutation.The exon 7/8 mutation frequency was 30.8% . There were significant relationships between radiation dose and mutation frequency of HPRT gene and exon 7/8 . Conclusion The DNA damage and gene mutation inducedby radiation has positive relationship with radiation dose, and is a basis of proliferation inhibition and apopto-sis of smooth muscle cells.

Objective:To investigate the relationship between the radiation dose and the HPRT gene lo-cus mutation in rat smooth muscle cells,and provide the molecular basis for prevention of restenosis after per-cutaneous transluminal coronary angioplasty(PTCA).Methods:The smooth muscle cells cultrued in vittro were irradiated by radionuclide^188Re in 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 reac-tion and single-strand conformation polymorphism.Results:The HPRT gene mutation frequency of rat smooth muscle cells that were irradiated by radionuclide^188Re ranged from 5.5×10^-6to 13×10^-6.Of 91 HPRT gene mutation colonies,13(14.3%)contained exon 7/8 deletion and 15(16.5%) had point mutation.The exon 7/8 mutation frequency was 30.8%.Three were significant relationships between radiation dose and mutation frequency of HPRT gene and exon 7/8.Conclusion:The DNA damage and gene mutation induced by radiation has positive relationship with radiation dose,and is a basis of proliferation inhibition and apopto-sis of smooth muscle cells.