Low doses of UVB or UVA induce chromosomal aberrations in cultured human skin cells.
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 gamma 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 gamma 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 gamma 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.
Emri
G
G
Department of Dermatology, University Medical School, Debrecen, Hungary.
Wenczl
E
E
Van Erp
P
P
Jans
J
J
Roza
L
L
Horkay
I
I
Schothorst
A A
AA
D002453:Cell Cycle / Q000528:radiation effects; D002478:Cells, Cultured; D002869:Chromosome Aberrations / Q000502:physiology*; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000528:radiation effects; D005434:Flow Cytometry / Q000379:methods; D005720:Gamma Rays; D006801:Humans; D007834:Lasers; D008544:Melanocytes / Q000528:radiation effects; D048629:Micronuclei, Chromosome-Defective / Q000528:radiation effects; D011829:Radiation Dosage; D012867:Skin / Q000166:cytology* / Q000528:radiation effects*; D013472:Sunlight / Q000009:adverse effects; D013997:Time Factors; D014466:Ultraviolet Rays