the role of rad51 protein in radioresistance of spheroid model of du145 prostate carcinoma cell line

background: rad51 is a protein with critical role in double strand break repair. down-regulation of this protein has a significant effect in radiosensitivity of some cell lines like prostate carcinoma. compared to monolayer cell culture model, the spheroids are more resistant to radiation. the aim of the current study was to determine the rad51 protein level in du145 spheroids, and monolayer cells before and after exposure to gamma irradiation. materials and methods: in the present study, western blot was used to determine the level of rad51 protein in du145 cell line grown as monolayer and spheroid. results: western blot analysis showed that in the spheroid cells, rad51 had an elevated level before and after radiation in comparison with monolayer cells. higher doses of radiation induced elevated expression of rad51 protein in both culture models. the level of at protein after exposure to gamma rays had been timedependent. conclusion: rad51 might act as a mediator of radiation resistance in tumor cells. repression of rad51 activity could be a prominent strategy to overcome radiation resistance of tumors. iran. j. radiat. res., 2009 7 (1): 19-25