X-ray Induction of Persistent Hypersensitivity to Mutation

Abstract

The progeny of x-irradiated V79 cells are hypersensitive to PUVA-(8-methoxypsoralen plus longwave ultraviolet light) induced mutation at the locus for hypoxanthine-guanine phosphoribosyl transferase. This hypersensitivity is most evident at low doses of pUVA that do not induce mutation in non-x-irradiated cells. The hypersensitivity is evoked by x-irradiation delivered as a single dose or as multiple fractions over a long period and persists for at least 108 days of exponential growth. This radiation-induced hypersensitivity to subsequent mutation is a new phenomenon that may be relevant to multistage carcinogenesis.