DNA repair in mouse embryo fibroblasts. II. Responses of nontransformed, preneoplastic and tumorigenic cells to ultraviolet irradiation.
Ultraviolet light-induced excision repair, as measured by single-strand DNA-break accumulation in the presence of hydroxyurea and 1-beta-D-arabinofuranosylcytosine, undergoes an apparent decline concomitant with spontaneous transformation of mouse cells in vitro. This decline is seen in preneoplastic transformed cells as well as tumorigenic cells, suggesting that it is an early event in transformation. The difference between nontransformed and transformed mouse cells in apparent incision rates is greatest at short times after irradiation when nontransformed cells show a transient phase of rapid incision. No gross differences in the effects of UV on replicative DNA synthesis, bulk RNA synthesis, cell proliferation or clonal survival in nontransformed and transformed cells were seen, in spite of the reduced incision capacity of the latter. Taken together the results suggest that transformed cells are capable of growth in the presence of significantly increased amounts of DNA damage. A decreased ability of nontumorigenic cells to remove DNA lesions, coupled with unrestricted growth, may be responsible for genetic alterations which increase the probability of a cell becoming tumorigenic.
D000818:Animals; D002455:Cell Division / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D002471:Cell Transformation, Neoplastic / Q000473:pathology / Q000528:radiation effects*; D004247:DNA / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D004261:DNA Replication / Q000528:radiation effects*; D004273:DNA, Neoplasm / Q000528:radiation effects; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects; D051379:Mice; D014466:Ultraviolet Rays
D004273:DNA, Neoplasm; D004247:DNA