Role of the human N-acetyltransferase 2 genetic polymorphism in metabolism and genotoxicity of 4, 4′-methylenedianiline

  • Raúl A. Salazar-González
  • Xiaoyan Zhang
  • Mark A. Doll
  • Angeliki Lykoudi
  • David W. HeinEmail author


4, 4′-Methylenedianiline (MDA) is used extensively as a curing agent in the production of elastomers and is classified as reasonably anticipated to be a human carcinogen based on sufficient evidence in animal experiments. Human N-acetyltransferase 1 (NAT1) and 2 (NAT2) catalyze the N-acetylation of aromatic amines and NAT2 is subjected to a common genetic polymorphism in human populations separating individuals into rapid, intermediate, and slow acetylator phenotypes. Although MDA is known to undergo N-acetylation to mono- and di-acetyl metabolites, very little is known regarding whether this metabolism is subject to the NAT2 genetic polymorphism. We investigated the N-acetylation of MDA by recombinant human NAT1, NAT2, genetic variants of NAT2, and cryoplateable human hepatocytes obtained from rapid, intermediate and slow acetylators. MDA N-acetylation was catalyzed by both recombinant human NAT1 and NAT2 exhibiting a fivefold higher affinity for human NAT2. N-acetylation of MDA was acetylator genotype dependent as evidenced via its N-acetylation by recombinant human NAT2 genetic variants or by cryoplateable human hepatocytes. MDA N-acetylation to the mono-acetyl or di-acetyl-MDA was highest in rapid, lower in intermediate, and lowest in slow acetylator human hepatocytes. MDA-induced DNA damage in the human hepatocytes was dose-dependent and also acetylator genotype dependent with highest levels of DNA damage in rapid, lower in intermediate, and lowest in slow acetylator human hepatocytes under the same MDA exposure level. In summary, the N-acetylation of MDA by recombinant human NAT2 and cryopreserved human hepatocytes support an important role for the NAT2 genetic polymorphism in modifying MDA metabolism and genotoxicity and potentially carcinogenic risk.


Human N-acetyltransferase 4, 4′-Methylenedianiline NAT2 polymorphism Genotoxicity Carcinogenic risk 



We appreciate our collaboration with BioIVT in providing cryoplateable human hepatocytes. The research was supported in part by USPHS grants P20-GM113226 and P42-ES023716. The authors gratefully acknowledge the contribution of the Erasmus+ International Credit Mobility program for faculty and student exchanges funded by the European Union. A preliminary report of this work was presented at the annual meeting of the Society of Toxicology, Baltimore, Maryland, March 2019.

Compliance with ethical standards

Conflict of interest

The authors declare no conflicts of interest.


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© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Pharmacology and Toxicology and James Graham Brown Cancer CenterUniversity of Louisville School of MedicineLouisvilleUSA
  2. 2.Department of Clinical PharmacologyADC TherapeuticsMurray HillUSA

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