Abstract
p53 is a tumor suppressor protein. It is shown that over 50% of all human tumors carry inactivating mutations in the p53 gene. In contrast to human leukemia MOLT-4 cells (p53 wild-type) which develop apoptosis after X-irradiation, mouse leukemic M10 cells (p53 mutant) undergo necrosis (Nakano and Shinohara, 1994). In addition, mild hyperthermia induces apoptosis in M10 cells (Nakano et al. 1997). In the present study M10 cells were transfected with wild-type p53 cDNA vector using DMRIE-C reagent. The stable transfectants were cloned by the colony formation in the presence of puromycin These transfectants were examined by PCR analysis and Western blot analysis. The loss of cell viability was determined by the dye exclusion test. The fraction of the transfectants stained with erythrosine B was low in unirradiated state, and was increased dramatically within 24h of incubation after 10 Gy-irradiation, while only a slight increase was observed for M10 cells. The increase of dead cells was dependent on X-ray doses. These results suggest that transfection of wild p53 to mutant p53-tumor cells is effective for radiosensitization.
