title: The tumor-initiating and -promoting effects of ionizing radiations in mouse skin.
abstract: The tumor-initiating and -promoting effects of ionizing radiation were tested, using mouse skin as the target organ and 90Sr-90Y beta-rays as the source of radiation. Neither single 2400 rad beta-irradiation followed by repetitive treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) nor single pretreatment with 7,12-dimethylbenz[alpha]anthracene (DMBA) followed by repetitive 470 rad beta irradiation produced tumors above the level of significance within a period of 210 days, while a positive control, DMBA + TPA, yielded a high incidence of papilloma in a shorter period. DMBA exerted an action antagonistic to beta-rays in the induction of malignant tumors. It is concluded that the tumor-enhancing activity of repetitive radiation is qualitatively different from the promoting activity of TPA.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D003043:Cocarcinogenesis; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D011839:Radiation, Ionizing; D012878:Skin Neoplasms / Q000209:etiology*; D013755:Tetradecanoylphorbol Acetate
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene; D013755:Tetradecanoylphorbol Acetate