Ultraviolet A does not induce melanomas in a Xiphophorus hybrid fish model.
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.
Mitchell
David L
DL
Department of Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX 78957, USA. dmitchel@mdanderson.org
Fernandez
André A
AA
Nairn
Rodney S
RS
Garcia
Rachel
R
Paniker
Lakshmi
L
Trono
David
D
Thames
Howard D
HD
Gimenez-Conti
Irma
I
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