HIGH-LEVELS OF DIPYRIMIDINE DIMERS ARE INDUCED IN HUMAN SKIN BY SOLAR-SIMULATING UV-RADIATION

UV light is considered an important contributor to skin cancer, but me thods have been lacking to quantify specific UV-induced lesions in hum an skin irt situ, We applied a newly developed P-32-postlabeling techn ique to measure specific UV-induced cyclobutane dimers and 6-4 dipyrim idine lesions in the skin of healthy volunteers. At a dose of 400 J/m( 2), solar-simulated radiation caused at Least 20 cyclobutane dimers/10 (6) nucleotides, which is much higher than any known DNA adducts induc ed by specific external chemical exposure in human target tissues. Thi s may explain why patients with DNA repair syndromes, such as xeroderm a pigmentosum, preferentially develop skin cancer, We applied the P-32 -postlabeling technique to study rates of DNA repair in healthy indivi duals. The obtained data indicated a base sequence dependence of the r epair process, The applied method has potential for the study of DNA r epair as a determinant of individual susceptibility to skin cancer.