5-Azacytidine-induced 6-thioguanine resistance at the gpt locus in AS52 cells: cellular response.

Treatment of AS52 cells with 5-azacytidine resulted in an induction of 6-thioguanine-resistant [6TG] colonies, which reached a maximum by an expression time of 9 days. Dose responses for both cytotoxicity and mutation induction were determined following treatment with 5-azacytidine. At 20 microM treatment, 5-azacytidine exposure resulted in about 50% survival. Mutant frequency reached a maximum of 10 microM. At concentrations between 10 and 20 microM, 5-azacytidine was a potent mutagen but did not exhibit a dose response. Although many compounds both induce cell death and affect the growth rate of cells, 5-azacytidine specifically induced cell death and did not affect the doubling time of the surviving treated cell population.