title: UV light from 290 to 325 nm, but not broad-band UVA or visible light, augments the formation of melanocytic nevi in a guinea-pig model for human nevi.
abstract: We have previously described a guinea-pig model where pigmented nevi similar to human nevi can be produced by application of low-dose topical 7,12-dimethylbenzanthracene (DMBA) followed by solar-simulated light. Five groups of guinea-pigs were used to test the effect of various spectral bands of solar-simulated light on low-dose DMBA-induced melanocytic nevi. Animals were irradiated with either UVB to near UVA2 (290-325 nm), UVA, visible light, full solar spectrum or no irradiation three times per wk for 12 mo to determine the broad-band effect of nevi-inducing irradiation. There was a significant increase in nevi/animal in the UVB-treated group (mean 1.53) compared with all groups (versus UVA 0.3, p<0.001; versus visible light 0.24, p<0.001; versus full spectrum (UVB+UVA+visible) 0.68, p=0.02; versus control (nil irradiation) 0.37, p=0.01). No differences in skin thickness were found between any group (p=0.11). In conclusion, we present a report of the active waveband of melanocytic nevi induction; where UVB to near UVA2 is the likely responsible waveband. Furthermore, because there was a significant decrease in nevi/animal receiving the full solar spectrum compared with the UVB group, it is possible that broad-band UVA and or visible light may be inhibitory wavebands for nevi induction.
authors.affiliation: Sydney Melanoma Diagnostic Centre, Sydney Cancer Institute, Royal Prince Alfred Hospital and Faculty of Medicine, University of Sydney, NSW 2006, Australia. scott.menzies@email.cs.nsw.gov.au
authors.forename: Scott W
authors.initials: SW
authors.lastname: Menzies
authors.forename: Gavin E
authors.initials: GE
authors.lastname: Greenoak
authors.forename: Chandrika M
authors.initials: CM
authors.lastname: Abeywardana
authors.forename: Kerry A
authors.initials: KA
authors.lastname: Crotty
authors.forename: Michael E
authors.initials: ME
authors.lastname: O'Neill
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002273:Carcinogens; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D008027:Light; D009508:Nevus, Pigmented / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D012867:Skin / Q000473:pathology / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D002273:Carcinogens; D015127:9,10-Dimethyl-1,2-benzanthracene