title: Ultraviolet A does not induce melanomas in a Xiphophorus hybrid fish model.
abstract: We examined the wavelength dependence of ultraviolet (UV) ra-diation (UVR)-induced melanoma in a Xiphophorus backcross hybrid model previously reported to be susceptible to melanoma induction by ultraviolet A (UVA) and visible light. Whereas ultraviolet B (UVB) irradiation of neonates yielded high frequencies of melanomas in pigmented fish, UVA irradiation resulted in melanoma frequencies that were not significantly different from unirradiated fish. Spontaneous and UV-induced melanoma frequencies correlated with the degree of pigmentation as expected from previous studies, and the histopathology phenotypes of the melanomas were not found in significantly different proportions in UV-treated and -untreated tumor-bearing fish. Our results support the conclusion that a brief early-life exposure to UVB radiation causes melanoma formation in this animal model. These data are consistent with an essential role for direct DNA damage, including cyclobutane dimers and (6-4) photoproducts, in the etiology of melanoma.
authors.affiliation: Department of Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX 78957, USA. dmitchel@mdanderson.org
authors.forename: David L
authors.initials: DL
authors.lastname: Mitchell
authors.forename: André A
authors.initials: AA
authors.lastname: Fernandez
authors.forename: Rodney S
authors.initials: RS
authors.lastname: Nairn
authors.forename: Rachel
authors.initials: R
authors.lastname: Garcia
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Paniker
authors.forename: David
authors.initials: D
authors.lastname: Trono
authors.forename: Howard D
authors.initials: HD
authors.lastname: Thames
authors.forename: Irma
authors.initials: I
authors.lastname: Gimenez-Conti
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D003532:Cyprinodontiformes; D006824:Hybridization, Genetic; D008546:Melanoma, Experimental / Q000209:etiology* / Q000473:pathology; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000473:pathology; D010858:Pigmentation / Q000528:radiation effects*; D012878:Skin Neoplasms / Q000209:etiology* / Q000473:pathology; D014466:Ultraviolet Rays