Contributions of human enzymes in carcinogen metabolism

Chem Res Toxicol. 2012 Jul 16;25(7):1316-83. doi: 10.1021/tx300132k. Epub 2012 May 10.


Considerable support exists for the roles of metabolism in modulating the carcinogenic properties of chemicals. In particular, many of these compounds are pro-carcinogens that require activation to electrophilic forms to exert genotoxic effects. We systematically analyzed the existing literature on the metabolism of carcinogens by human enzymes, which has been developed largely in the past 25 years. The metabolism and especially bioactivation of carcinogens are dominated by cytochrome P450 enzymes (66% of bioactivations). Within this group, six P450s--1A1, 1A2, 1B1, 2A6, 2E1, and 3A4--accounted for 77% of the P450 activation reactions. The roles of these P450s can be compared with those estimated for drug metabolism and should be considered in issues involving enzyme induction, chemoprevention, molecular epidemiology, interindividual variations, and risk assessment.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Carcinogens / metabolism*
  • Chemoprevention
  • Cytochrome P-450 Enzyme System / metabolism
  • Enzymes / metabolism*
  • Humans
  • Inactivation, Metabolic
  • Risk Assessment


  • Carcinogens
  • Enzymes
  • Cytochrome P-450 Enzyme System