Metabolism and genotoxicity of 4,4'-oxydianiline is dependent on N-acetyltransferase 2 genetic polymorphism.

4,4'-oxydianiline (ODA) is an environmental aromatic amine reasonably anticipated to be a human carcinogen. We investigated ODA genotoxicity and oxidative stress modified by N-acetyltransferase 2 (NAT2) genetic polymorphism in yeast and DNA repair deficient (UV5) Chinese hamster ovary cells (CHO) expressing human NAT2*4 (rapid acetylator allele) or human NAT2*5B (slow acetylator allele) and in cryopreserved human hepatocytes from rapid, intermediate, or slow NAT2 acetylator genotypes. N-acetylation of ODA was both concentration- and time-dependent and significantly higher in yeast and CHO cells expressing NAT2*4 versus NAT2*5B. ODA-induced DNA damage response and reactive oxygen species (ROS/RNS) were significantly higher, while intracellular reduced glutathione (GSH) and oxidized glutathione (GSSG) ratio or mitochondrial integrity were significantly lower in CHO cells expressing NAT2*4 than NAT2*5B. Dose- and NAT2 phenotype-dependent responses also were observed in human cryopreserved human hepatocytes. Our findings have important implications for precise risk assessments following exposures to ODA and azo dye precursors.