title: Differential features of sister-chromatid exchange responses to ultraviolet radiation and caffeine in xeroderma pigmentosum lymphoblastoid cell lines.
abstract: Sister-chromatid exchange (SCE) induced by ultraviolet (UV) irradiation and viability after UV irradiation were studied in lymphoblastoid cell lines derived from 7 patients with xeroderma pigmentosum (XP) and 6 normal donors. UV irradiation caused significant increases of SCEs in both XP and normal cells. In 3 XP cell lines, which were deficient in unscheduled DNA synthesis (UDS) and sensitive to the killing effect of UV, very high SCE frequencies were observed after UV irradiation. Cells from a patient with the De Sanctis-Cacchione syndrome were the most sensitive to UV in terms of both SCE induction and cell killing. In 2 of 4 UDS-proficient XP cell lines tested, the incidences of UV-induced SCEs were similar to those in normal cell lines, but in 2 other UDS-proficient lines from 2 XP patients with skin cancer, the frequencies of UV-induced SCEs were significantly higher than in normal cells. Continuous post-UV treatment with 1 mM caffeine markedly enhanced UV-induced SCEs in 3 of 4 UDS-proficient XP cell lines but had only slight effects on cells from the 4th UDS-proficient XP patient and from normal individuals.
mesh_terms: D002110:Caffeine / Q000494:pharmacology*; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D003434:Crossing Over, Genetic / Q000528:radiation effects*; D004247:DNA / Q000096:biosynthesis; D004260:DNA Repair / Q000528:radiation effects; D006801:Humans; D008214:Lymphocytes; D012854:Sister Chromatid Exchange / Q000187:drug effects / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics*
chemical_list: D002110:Caffeine; D004247:DNA