Pretreatment with Low-density Carbon Ions Induces Enhanced Mutation Induction in Normal Human Fibroblasts Following Irradiation with Acute X Rays.

Abstract

We have been studying cellular responses in normal human fibroblasts exposed to low-density high LET radiations. This year we focused on the induction of genomic instability in mutation induction detected with a 6-thioguanie resistant clone targeted on hprt locus. Cells were pretreated with either low-density carbon ions (~1mGy/7h) or low-dose ¹³⁷Cs gamma rays (~0.9mGy/7h) before following irradiation with X-ray challenging doses. There observed no difference in mutation frequency at 1.5Gy of X-ray challenging dose between un-pretreated and gamma-ray pre-treated cells. On the other hand, it was around 7 times higher in carbon-ion pretreated cells than in un-pretreated cells. The results suggest that the pretreatment of low-density carbon ions induce genomic instability in mutation induction.