Repair of indirectly induced DNA damage in human skin fibroblasts treated with N-hydroxy-2-naphthylamine.

The DNA lesions induced by active oxygen species generated from N-hydroxy-2-naphthylamine were quantitated by the alkaline elution technique as single-strand breaks using cultured human-skin fibroblasts. When cells were treated at 20 degrees C for 2 h with 0-25 microM carcinogen, the lesions increased biphasically with the concentration; the increase was slight below 10 microM while it was much larger and dose-dependent above this concentration. The dose response was similar for normal and xeroderma pigmentosum fibroblasts of complementation group A. There was no difference in the repair rate of single-strand breaks formed in these fibroblasts. The rates of repair of single strand breaks induced by N-hydroxy-2-naphthylamine and hydrogen peroxide were similar but slower than that of the repair of gamma-ray-induced single-strand breaks.