The recovery of mammalian cells treated with methyl methanesolfonate, nitrogen mustard or UV light. II. The importance of DNA repair prior to the initiation of S phase.
CHO cells were synchronized 2 G1 phase and treated with UV light or HN2. These treatments resulted in a dose-dependent reduction in the rate of DNA replication and cell survival. Holding UV-irradiated cells in G1 phase (in HU medium) for an additional 10 h prior to their release into S phase did not assist recovery as measured by either of these criteria. The survival of cells treated with HN2 was also not enhanced by this recovery period. However, following 2 X 10(-5) M HN2 the rate of DNA replication increased from 30% to 70% of the control level when the period in HU medium was extended to 14 h. The induction of cross-links following HN2 treatment of asynchronous cells was shown to be dose dependent. Subsequent incubation in fresh medium resulted in complete recovery within 20 h at concentrations of HN2 up to 10(-5) M, and at 2 X 10(-5) M HN2, 75% of the cross-links were removed at 14 h post treatment.
D000818:Animals; D002453:Cell Cycle; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000235:genetics*; D004260:DNA Repair / Q000187:drug effects*; D004261:DNA Replication / Q000187:drug effects; D005260:Female; D007399:Interphase; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D009588:Nitrogen Mustard Compounds / Q000494:pharmacology; D010053:Ovary / Q000166:cytology
D009588:Nitrogen Mustard Compounds; D004247:DNA; D008741:Methyl Methanesulfonate