Defective DNA repair in cultured melanocytes from xeroderma pigmentosum patients.
The DNA repair of ultraviolet (UV)-induced damages in primary cultured melanocytes from xeroderma pigmentosum (XP) patients and normal subjects were studied by measuring unscheduled DNA synthesis (UDS) on autoradiographs. Melanocytes were cultured in alpha-minimum essential medium (alpha-MEM) supplemented with 10% fetal calf serum (FCS), 12-O-tetradecanoyl-phorbol-13 acetate (TPA), and geneticin. The levels of UDS in XP melanocytes were compared with those in normal melanocytes. In both normal and XP melanocytes, post-UV-UDS increased dose-dependently at doses of 5-10 J/m2. XP melanocytes exhibited various levels of defect in DNA repair, depending on the type of XP. Melanocytes from XP-A patients displayed very low levels of UDS, only 6.2-8.4% that of the normal melanocytes. However, UDS values in melanocytes from intermediate groups, XP-D, XP-E, and XP-F, were relatively high, 37.2-53.5% of the control in XP-D, 50.0-66.5% in XP-E, and 38.2-46.7% in XP-F, respectively. Melanocytes from XP-variant patients exhibited almost normal levels of UDS, 87.7-91.6% of those from normal subjects. The levels of UDS in XP melanocytes were very similar to those in fibroblasts isolated from the same specimens.
Yamaguchi
J
J
Department of Dermatology, School of Medicine, Tokyo Medical and Dental University, Japan.
Mamada
A
A
Kondo
S
S
Satoh
Y
Y
D000293:Adolescent; D000328:Adult; D001345:Autoradiography; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000096:biosynthesis / Q000528:radiation effects; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D008297:Male; D008544:Melanocytes / Q000378:metabolism*; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics*
D004247:DNA