title: Induction of 5,6-ring-saturated thymine bases in NIH-3T3 cells by phorbol ester-stimulated macrophages: role of reactive oxygen intermediates.
abstract: Because oxygen intermediates secreted by inflammatory leukocytes are postulated to play a role in potentiating carcinogenesis, we investigated the ability of macrophages to induce oxidative DNA damage in eukaryotic cells. Murine macrophages, obtained from sites of inflammation and stimulated with 12-O-tetradecanoylphorbol-15-acetate, induced the formation of 5,6-ring-saturated thymine bases in the DNA of cocultured NIH-3T3 cells; macrophages or 12-O-tetradecanoylphorbol-15-acetate alone did not induce such alterations. Reagent H2O2, at concentrations produced by macrophages in the ambient medium (i.e., approximately 10(-5) M), induced saturated thymines in the target cells in a dose-dependent manner. The reaction between reagent H2O2 and cellular DNA was rapid, reaching maximum levels in 30 min, and similar amounts of saturated thymines were induced at 4 degrees or 37 degrees. The 3T3 targets were able to repair the saturated thymines rapidly (i.e., over 70% of the lesion was removed in 2 hr). Catalase completely inhibited macrophage-mediated induction of saturated thymines, although superoxide dismutase enhanced induction. Taken together, the data indicate that macrophages exposed to phorbol diesters can induce a specific, quantifiable lesion in the DNA of bystander eukaryotic cells and that reactive oxygen species from the macrophages participate in producing the lesion.
mesh_terms: D000818:Animals; D002374:Catalase / Q000494:pharmacology; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D003872:Dermatitis / Q000473:pathology; D006861:Hydrogen Peroxide / Q000378:metabolism; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D010100:Oxygen / Q000378:metabolism*; D010704:Phorbols / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity*; D013941:Thymine / Q000378:metabolism*
chemical_list: D010704:Phorbols; D004247:DNA; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D013755:Tetradecanoylphorbol Acetate; D013941:Thymine; D010100:Oxygen