Chromatid Breakage: Differential Effect of Inhibitors of DNA Synthesis during G2 Phase

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Science  06 Oct 1972:
Vol. 178, Issue 4056, pp. 62
DOI: 10.1126/science.178.4056.62


The cell cycle specificity of chromatid breakage induced by inhibitors of DNA synthesis depends on the mechanism of drug action. 5-Hydroxy-2-formylpyridine thiosemicarbazone, hydroxyurea, and guanazole, compounds that inhibit ribonucleotide reductase, do not cause chromatid breakage during G2 phase. In contrast, two active antitumor agents, arabinosylcytosine and 5-azacytidine, which are either incorporated into polynucleotides or affect DNA polymerase, produce chromatid breakage during G2 phase. All of these agents except guanazole also induce breakage in S phase.