Depression of mutation induced with near ultraviolet light (UV-B) by vitamin C

Abstract

We have found long-lived radicals(LLR) with long half-time (T1/2 is over 20 hr) in X-irradiated cells, previously. LLR is a cause of mutation, but it is not a cause of cell death. Therefore, LLR may contribute to cancer and senescence through mutation. Recently, we also found that LLR was induced in a cell irradiated with UV-B. In this experiment, we examined whether vitamin C could scavenge LLR induced by UV-B, and whether it could depress induction of mutation. Actually, the cells were treated with 5mM of vitamin C both for 2 hr before X-irradiation and for 2hr from 20min after X-irradiation. Vitamin C didn't affect the survival of cells exposed to UV-B, which indicates that vitamin C didn't scavenge active short life time radicals but LLR. However, both pre- and post-treatment with vitamin C reduced mutation frequency in the UV-irradiated cells. These results suggest that LLR are involved in the induction of mutation by UV-B light.