抄録
In this study, we examined whether X-ray-induced gene deletion at the HPRT locus induces delayed instability in X-chromosome. SV40-immortalized normal human fibroblasts, GM638, were irradiated with 3 Gy of X-rays, and the HPRT mutants were isolated in the medium containing 60 µM of 6-thioguanine. The molecular structure of the HPRT mutations was determined by multiplex polymerase chain reaction of the eight exons of the HPRT gene. The size of deletions in total HPRT deletion mutants were determined by PCR amplification using sequence tagged site (STS) primers. Delayed chromosomal instability in X-chromosome was analyzed by whole human X-chromosome paint FISH. GM638 and spontaneous mutants, which showed no detectable change in the HPRT gene, did not induce X-chromosomal rearrangements, however, 3 Gy-induced mutants with large deletion showed delayed instability involving X-chromosome. These results suggest that ionizing radiation-induced large deletion is involved in initiation and perpetuation of radiation-induced genomic instability. [J Radiat Res 44:442 (2003)]
