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Low doses of UVB or UVA induce chromosomal aberrations in cultured human skin cells

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Author: Emri, G. · Wenczl, E. · Erp, P. van · Jans, J. · Roza, L. · Horkay, I. · Schothorst, A.A.
Type:article
Date:2000
Institution: Centraal Instituut voor Voedingsonderzoek TNO
Source:The Journal of Investigative Dermatology, 3, 115, 35-440
Identifier: 87321
doi: doi:10.1046/j.1523-1747.2000.00057.x
Keywords: Nutrition · Human fibroblasts · Human melanocytes · Micronuclei · Skin cancer · 1,6 diphenyl 1,3,5 hexatriene · Ethidium bromide · Cell kinetics · Chromosome aberration · Fibroblast · Flow cytometry · Human · Human cell · Ionizing radiation · Priority journal · Skin carcinogenesis · Skin disease · Ultraviolet radiation · Cell Cycle · Cells, Cultured · Chromosome Aberrations · Dose-Response Relationship, Radiation · Fibroblasts · Flow Cytometry · Gamma Rays · Humans · Lasers · Melanocytes · Micronuclei, Chromosome-Defective · Radiation Dosage · Skin · Sunlight · Time Factors · Ultraviolet Rays

Abstract

Chromosomal defects are frequently present in malignant and premalignant skin disorders; however, it is not known whether ultraviolet radiation from sunlight plays a role in their induction. To obtain information on the ability of ultraviolet A and ultraviolet B to induce chromosomal aberrations, cultured melanocytes and fibroblasts were exposed to physiologic doses of ultraviolet A or ultraviolet B and, for comparison, to γ rays. As a measure of chromosomal aberrations, the formation of micronuclei was determined. To obtain sufficient statistical data on induced micronuclei and cell kinetics, a flow cytometry method has been modified and applied. The flow cytometry method analysis is based on staining the DNA with ethidium bromide and the cell membranes with 1,6-diphenyl-1,3,5,-hexatriene. We observed dose-dependent micronuclei formation after γ or ultraviolet B irradiation in both cell types and also for ultraviolet A in fibroblasts. The yield of micronuclei induced in fibroblasts by ultraviolet A was only a factor 15 smaller than that induced by ultraviolet B (313 nm). The results indicate that 10 kJ per m2 (equivalent to 1 minimal erythema dose) of ultraviolet B and 150 kJ per m2 of ultraviolet A (0.2 minimal erythema dose) can induce 1% of micronuclei in fibroblasts, equivalent to the induction due to 0.6 Gy of γ radiation. In conclusion, physiologic doses of sunlight can induce chromosomal aberrations at a level comparable with that observed after exposure to approximately 1 Gy of ionizing radiation. Therefore, sunlight can be considered a potential inducer of chromosomal aberrations in skin cells, which may contribute to skin carcinogenesis.