Decreased DNA repair activity in sunburn cells

Abstract

The pathogenesis of the formation of sunburn cells is unknown. Based on autoradiographic methods the unscheduled DNA repair synthesis of UV-induced thymin dimers was investigated in vivo in sunburn cells and in irradiated but histologically normal stratum spinosum cells. The results show a significant lower number of sparsly labeled cells in the sunburn cell-population (13.2±2.5; mean) when compared to the population of normal stratum spinosum cells (57.8±7.5; mean). These data indicate that the population of those epidermal cells, which become manifest as sunburn cells 24 h after UV exposure exhibit a reduced DNA repair of UV induced thymine dimers immediately after UV irradiation. Nuclear factors thus seem to play at least some role in the origin of sunburn cells. Die Pathogenese der Entstehung von Sonnenbrandzellen ist unbekannt. Die nicht schematisierte (unscheduled) DNA-Synthese von UV-induzierten Thymindimeren wurde in Sonnenbrandzellen sowie in UV-bestrahlten, aber histologisch unauffälligen Stratum spinosum-Zellen autoradiographisch in vivo untersucht. Es fand sich die Zahl locker markierter Zellen innerhalb der Sonnenbrandzellen-Population (13,2±2,5; Mittelwert) gegenüber der Zahl locker markierter Zellen in der Population normaler Stratum spinosum-Zellen (57,8±7,5; Mittelwert) signifikant vermindert. Die Resultate deuten darauf hin, daß die Population jener Epidermalzellen, die 24 h nach UV-Bestrahlung zu Sonnenbrandzellen werden, kurz nach der UV-Exposition eine verminderte DNS-Reparatur von Thymindimeren aufweist.