P53 ACCUMULATION IN THE ORGANS OF LOW-DOSE X-RAY-IRRADIATED MICE

In order to search for the direct evidence of cellular response to low -dose radiation, we investigated wild-type p53 protein accumulation in several organs of mice after exposure to low doses of X-rays. Signifi cant p53 accumulation within 24 h was observed in the mouse adrenal gl ands and pancreas after X-ray irradiation at 25 cGy and 50 cGy, but no t at 100 cGy. In addition, differential p53 accumulation was also obse rved in the hypophysis, thymus, skin, lung, bone marrow and liver at d ifferent doses. In contrast, we observed no accumulation of p53 protei n in the spleen, testis or kidney at any dose used in this experiment. The p53 accumulation induced by low-dose X-rays in mice was organ-spe cific. It is suggested that cell type and interactions with other sign al transduction pathways of the hormone system, immune system and/or n ervous system may contribute to the variable induction of p53 by low-d ose X-ray irradiation. The association of organ-specific p53 response with radiosensitivity and cancer incidence by radiation in each organ was discussed.