DNA EXCISION REPAIR IN ULTRAVIOLET-IRRADIATED NORMAL AND MALIGNANTLY TRANSFORMED MOUSE EPIDERMAL-CELL CULTURES

  • 1 January 1977
    • journal article
    • research article
    • Vol. 37  (6) , 1611-1617
Abstract
Pyrimidine dimer production and excision were studied in UV irradiated primary cultures of epidermal cells derived from perinatal mouse skin and in an in vitro malignantly transformed epidermal cell line. Dimer production increased linearly with UV dose level for both cell types. At any given UV dose level, there were 20% fewer thymine containing dimers induced in the primary cultures compared to the transformed cell line. The reduced dimer yield in the primary cultures was attributed to the multilayer structure (3 cell layers) of these cultures. The primary cultures excised no more than 10% of the original dimers in a 24 h period, while the malignantly transformed cells excised 34%. Nonsemiconservative DNA repair synthesis was also studied as a function of dimer yields in the first 3 h after irradiation. When the levels of repair replication in both cell types were compared at equal yields of UV induced dimers, the malignantly transformed cells exhibited a higher level of repair than the primary epidermal cells. There was no difference in the kinetics of repair replication between the 2 cell types at a UV dose level of 10 J/m2 over the first 6 h after irradiation.