Effect of the metal chelating agent o-phenanthroline on the DNA and chromosome damage induced by bleomycin in Chinese hamster ovary cells.

A 30-min pulse treatment with bleomycin to Chinese hamster ovary cells in culture produces DNA degradation and chromosomal aberrations in a dose-dependent manner. Bleomycin also induces a long-lasting effect on the cell cycle producing a lengthening of two or more cycles after the treatment. The presence of o-phenanthroline, which chelates metal ions, totally inhibits DNA cleavage and the appearance of chromosome aberrations while partially correcting the lengthening of the cell cycle. These findings suggest that an important cellular target for bleomycin is the DNA. Chromosomal aberrations are a secondary effect resulting from DNA cleavage. On the other hand, the increase in the duration of the cell cycle is probably induced by DNA degradation and, perhaps, by damage to other cellular structures.