The induction of DNA strand breaks in normal human skin fibroblasts exposed to solar ultraviolet radiation.
The levels of apparent DNA single-strand breaks (ssb) were measured, following a 0-20 h incubation of normal human skin fibroblasts exposed to the solar uv wavelengths produced by a fluorescent sunlamp. The ssb were determined using the alkaline elution assay, which was performed either without proteinase K (proK) or in its presence, so as to eliminate any DNA-protein crosslinks that may be present in the cells. Cells were irradiated with either 3 kJ/m2 of sunlamp uv greater than 295 nm, 150 kJ/m2 of sunlamp uv greater than 315 nm, or 150 kJ/m2 of sunlamp uv greater than 320 nm. These treatments resulted in the production of 5-10 ssb/10(10) Da. For the two shorter wavelength irradiations, the levels of ssb decreased rapidly upon incubation of the cells. However, when the elutions were performed using proK, the number of ssb increased about twofold following a 2-4 h incubation. In contrast, the levels of ssb decreased in the sunlamp uv greater than 320 nm irradiated cells for elutions performed with or without proK. These results suggest that under certain irradiation conditions, ssb are formed in cells upon incubation, which are hidden by the crosslinking of protein to DNA.
Rosenstein
B S
BS
Department of Radiation Medicine, Box G, Brown University, Providence, Rhode Island 02912.
D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000528:radiation effects*; D005347:Fibroblasts / Q000528:radiation effects; D006801:Humans; D066298:In Vitro Techniques; D012867:Skin / Q000166:cytology / Q000528:radiation effects*; D013472:Sunlight; D014466:Ultraviolet Rays
D004277:DNA, Single-Stranded