Effect of age on the formation and repair of UV photoproducts in human skin in situ.
Ultraviolet radiation (UVR)-induced photoproducts can be measured by a number of methods. The newly developed 32P-postlabelling method is feasible in molecular epidemiological studies due to its sensitivity, specificity and little amount DNA needed. We applied the 32P-postlabelling method to investigate the induction and repair of photoproducts (cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts) after UVR in human skin in situ and studied the effects of age, skin type and gender. The study included 30 subjects aged 32-78 years. The photoproduct induction levels varied 7- to 15-fold between the individuals tested. All four types of photoproducts were induced at a higher frequency in the older population (>/=50 years) than in the younger population (<50 years). Individuals with skin type I and II had a higher CPD induction frequency than individuals with skin type III and IV. In both cases, the differences in thymidylyl (3'-5') thymidylyl (3'-5')-2'-deoxycytidine induction reached statistical significant levels (p<0.05). Photoproduct repair rates 24 h and 48 h after UV irradiation showed a large inter-individual variation. No clear effects of age, skin type or gender on DNA repair could be detected. Our data suggest that UV-induced DNA photoproduct levels increase with age.
Xu
G
G
Department of Biosciences, Karolinska Institute, S-14157, Huddinge, Sweden. guogang.xu@csb.ki.se
Snellman
E
E
Bykov
V J
VJ
Jansen
C T
CT
Hemminki
K
K
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D001706:Biopsy; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000032:analysis / Q000528:radiation effects; D004260:DNA Repair / Q000502:physiology* / Q000528:radiation effects; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010761:Phosphorus Radioisotopes; D011740:Pyrimidine Dimers / Q000032:analysis / Q000378:metabolism*; D012044:Regression Analysis; D012737:Sex Factors; D012867:Skin / Q000737:chemistry / Q000166:cytology / Q000528:radiation effects*; D014466:Ultraviolet Rays
D010761:Phosphorus Radioisotopes; D011740:Pyrimidine Dimers; C058406:pyrimidine-pyrimidone dimer; D004247:DNA