SULFOTRANSFERASE-MEDIATED DNA-BINDING OF N-HYDROXYARYLAMINES(AMIDE) IN LIVER CYTOSOLS FROM HUMAN AND EXPERIMENTAL-ANIMALS

Characteristics of cytosolic sulfotransferase-mediated binding of carcinogenic N-hydroxyarylamines(amide) have been investigated and compared among experimental animal species and humans in vitro. Human cytosols exhibited significant sulfating activities towards 2-hydroxyamino-6-methyldipyrido[1,2-a:3',2'-d]imidazole (N-hydroxy-Glu-P1), N-hydroxy-2-aminonuorene (N-hydroxy-AF) and N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF), but had no detectable activity toward 2-hydroxyamino-3-methylimidazo[4,5-f]quinoline (N-hydroxy-IQ). Although the extent of the covalent binding of these N-hydroxyarylamines(amide) differed significantly among individuals, clear correlations were observed among the sulfation of N-hydroxyarylamines (amide) and also with p-nitrophenol sulfation. Hepatic cytosols from mouse, rat, guinea-pig, hamster, rabbit, dog and monkey also mediated the binding of N-hydroxy-Glu-P-1, N-hydroxy-AF and N-hydroxy-AAF, while only rat cytosols showed detectable DNA binding of N-hydroxy-IQ. Among the species examined, rat showed the highest capability for activating these N-hydroxyarylamines(amides). Significant sex-related differences were detected in rat, dog and monkey for all substrates examined, except N-hydroxy-IQ. Clear correlations were observed in the animal species between N-hydroxyarylamines(amide), but not with p-nitrophenol. Using an ion-exchange chromatographic system, sulfating activity of p-nitrophenol in human livers was separated into two fractions and the PAPS-dependent DNA binding of N-hydroxy-AF was supported mainly by the later fraction. On Western blots, an immunoreactive protein was detected in these fractions using an antibody raised against rat hepatic N-hydroxy-AAF sulfotransferase. The band was also detected in human hepatic cytosols with considerable individual variation in their amounts. These results indicate the involvement of a closely related form(s) of sulfotransferase in the PAPS-mediated activation of N-hydroxyarylamines(amide) in human as well as in the experimental animal species.