Authors: Ghanayem, Burhan I.; Hoffler, Undi

Source: Current Drug Metabolism, Volume 8, Number 7, October 2007 , pp. 728-749(22)

Publisher: Bentham Science Publishers

Abstract:

Cytochromes P450 (CYPs) comprise a number of enzyme subfamilies responsible for the oxidative metabolism of a wide range of therapeutic agents, environmental toxicants, mutagens, and carcinogens. In particular, cytochrome P450 2E1 (CYP2E1) is implicated in the oxidative bioactivation of a variety of small hydrophobic chemicals including a number of epoxide-forming drugs and environmentally important toxicants including urethane, acrylamide, acrylonitrile, benzene, vinyl chloride, styrene, 1-bromopropane, trichloroethylene, dichloroethylene, acetaminophen, and butadiene. Until recently, chemical modulators (inducers and inhibitors) were used in order to characterize the enzymatic basis of xenobiotic metabolism and the relationships between CYP-mediated bioactivation and chemical-induced toxicity/carcinogenicity. With the advent of genetically engineered knockout mice, the ability to evaluate the roles of specific CYPs in the metabolism of xenobiotics has become more attainable. The main focus of the current review is to present studies that characterized the enzymatic, metabolic, and molecular mechanisms of toxicity, genotoxicity, and carcinogenicity of various xenobiotics using Cyp2e1-/- mice. Data presented in this review demonstrated that the most comprehensive studies using Cyp2e1-/- mice, encompassing the entire paradigm of metabolism to toxicity, genotoxicity, and carcinogenicity were possible when a substrate was primarily metabolized via CYP2E1 (e.g. urethane and acrylamide). In contrast, when multiple CYP enzymes were prevalent in the oxidation of a particular substrate (e.g.: trichloroethylene, methacrylonitrile, crotononitrile), investigating the relationships between oxidative metabolism and biological activity became more complicated and required the use of chemical modulators. In conclusion, the current review showed that Cyp2e1-/- mice are a valuable animal model for the investigation of the metabolic and molecular basis of toxicity, genotoxicity, and carcinogenicity of xenobiotics.

Keywords: cytochrome P inducers; polymorphisms; Urethane; vinyl carbamate epoxide; cell cycle genes; acetaminophen

Document Type: Research article

Publication date: 2007-10-01

More about this publication?

• Current Drug Metabolism aims to cover all the latest and outstanding developments in drug metabolism and disposition. The journal serves as an international forum for the publication of timely reviews in drug metabolism. Current Drug Metabolism is an essential journal for academic, clinical, government and pharmaceutical scientists who wish to be kept informed and up-to-date with the latest and most important developments. The journal covers the following areas:
  
  In vitro systems including CYP-450; enzyme induction and inhibition; drug-drug interactions and enzyme kinetics; pharmacokinetics, toxicokinetics, species scaling and extrapolations; P-glycoprotein and transport carriers; target organ toxicity and interindividual variability; drug metabolism and disposition studies; extrahepatic metabolism; phase I and phase II metabolism; recent developments for the identification of drug metabolites and adducts.

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