The significance of DNA damage in the cell cycle sensitivity of Chinese hamster ovary cells to bleomycin.

Chinese hamster ovary cells have been treated with bleomycin at various stages in the cell cycle. Mitotic cells, which exhibit least survival, show the greatest amount of DNA strand breakage and a marked inhibition of DNA replication in the subsequent S phase. Strand-rejoining experiments suggest that this is primarily due to differences in the amount of damage produced in the DNA but does not exclude the possibility that cells at the various cell stages also differ in their ability to repair this damage. DNA breakage also occurs in cells incubated in bleomycin at 4 degrees.