Inter-individual variation in the mutagenic activation of 2-acetylaminofluorene by human liver in relation to animal metabolic models

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Abstract
A relatively large, reproducible inter-individual variation was found in the ability of 17 human liver S9 samples to mediate the mutagenicity of 2-acetylaminofluorene (2AAF) in Salmonella typhimurium strain TA98. In an animal model, variation in metabolic activation of 2AAF did not appear to relate to the phenotype of debrisoquine 4-hydroxylase since hepatic S9 from poor and extensive metabolizer phenotypes (female DA and female Wistar rat, respectively) mediated the mutagenicity of this aromatic amide equally well. Approximately onethird of human liver samples exhibited an ability to detoxify 2AAF in a modified bacterial mutagenicity assay in a manner similar to that shown by guinea pig (but not rat or rabbit) S9. However, only in 2/14 human preparations was the detoxification inhibited by 8-hydroxyquinoline which has previously been recognized as an inhibitor of a detoxifying ‘transoxygenation’ in guinea pig liver. The results support a growing body of evidence for inter-individual variation in human carcinogen metabolism which may be important in determining susceptibility to chemical carcinogenesis.