Detection of mammalian cell mutagens in urine from carcinogen-dosed mice

Urine from drug-treated rodents was tested directly in the L5178Y TK+/-leads to TK-/- gene mutation assay for the induction of trifluorothymidine-resistant (TFTR) mutants. 18-h urine samples collected from male CD-1 mice which had been treated with either 2-aminofluorene, cyclophosphamide, or lucanthone were incubated with beta-glucuronidase, then added directly to cultures of L5178Y TK+/- mouse lymphoma cells for 3 h. All 3 urine sources produced significant, dose-dependent increases in the frequency of TFTR mutants compared to normal urine or saline controls. When these same chemicals were tested directly as mutagens in L5178Y TK+/- cells, lucanthone and, to a lesser extent, cyclophosphamide were positive both with or without metabolic activation; and aminofluorene was only positive with activation. These results indicate that the urinary metabolites of aminofluorene, cyclophosphamide, and either the parental molecule or urinary metabolites of lucanthone can readily be detected as mutagens in a mammalian cell assay.