title: Prevention of chemically induced two-stage skin carcinogenesis in mice by systemic effects of ultraviolet irradiation.
abstract: Systemic effects of UVB irradiation (280 to 320 nm) have been shown to enhance subsequent carcinogenesis induced by UV irradiation or by high doses of benzo[a]pyrene. In the present study, we asked whether the systemic effects of UVB irradiation would influence subsequent chemical tumorigenesis induced by the initiation-promotion protocol. A group of B6D2F1/J mice were irradiated dorsally with five 30-min treatments per week for 11.5 weeks. The irradiation source was a bank of six unfiltered Westinghouse FS40 sun lamps. One week later, irradiated and unirradiated mice were initiated ventrally with 100 micrograms of 7,12-dimethylbenz[a]anthracene. Four days later, ventral 12-O-tetradecanoylphorbol-13-acetate treatments were begun. After 20 weeks of promotion, there were 75% fewer tumors per mouse in the irradiated mice than in unirradiated mice. Thus, systemic effects of UVB irradiation resulted in inhibition of chemical carcinogenesis induced with an initiation-promotion protocol.
authors: Department of Radiation Oncology, University of Arizona College of Medicine, Tucson 85724.
authors: H L
authors: HL
authors: Gensler
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000378:metabolism; D003043:Cocarcinogenesis; D051379:Mice; D012867:Skin / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D014466:Ultraviolet Rays
chemical_list: D002117:Calcitriol