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Oxidative stress mediated toxicity exerted by ethanol-inducible CYP2E1.
Toxicol Appl Pharmacol. 2005 Sep 01; 207(2 Suppl):70-6.TA

Abstract

Induction of CYP2E1 by ethanol is one of the central pathways by which ethanol generates a state of oxidative stress in hepatocytes. To study the biochemical and toxicological actions of CYP2E1, our laboratory established HepG2 cell lines which constitutively overexpress CYP2E1 and characterized these cells with respect to ethanol toxicity. Addition of ethanol or an unsaturated fatty acid such as arachidonic acid or iron was toxic to the CYP2E1-expressing cells but not control cells. This toxicity was associated with elevated lipid peroxidation and could be prevented by antioxidants and inhibitors of CYP2E1. Apoptosis occurred in the CYP2E1-expressing cells exposed to ethanol, arachidonic acid, or iron. Removal of GSH caused a loss of viability in the CYP2E1-expressing cells even in the absence of added toxin or pro-oxidant. This was associated with mitochondrial damage and decreased mitochondrial membrane potential. Low concentrations of iron and arachidonic acid synergistically interacted with CYP2E1 to produce cell toxicity, suggesting these nutrients may act as priming or sensitizing agents to alcohol-induced liver injury. Surprisingly, CYP2E1-expressing cells had elevated GSH levels, due to transcriptional activation of glutamate cysteine ligase. Similarly, levels of catalase, alpha-, and microsomal glutathione transferase were also increased, suggesting that upregulation of these antioxidant genes may reflect an adaptive mechanism to remove CYP2E1-derived oxidants. Using co-cultures, interaction between CYP2E1-derived diffusible mediators to activate collagen production in hepatic stellate cells was found. While it is likely that several mechanisms contribute to alcohol-induced liver injury, the linkage between CYP2E1-dependent oxidative stress, mitochondrial injury, stellate cell activation, and GSH homeostasis may contribute to the toxic action of ethanol on the liver. HepG2 cell lines overexpressing CYP2E1 may be a valuable model to characterize the biochemical and toxicological properties of CYP2E1.

Authors+Show Affiliations

Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA.No affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Review

Language

eng

PubMed ID

16019049

Citation

Wu, Defeng, and Arthur I. Cederbaum. "Oxidative Stress Mediated Toxicity Exerted By Ethanol-inducible CYP2E1." Toxicology and Applied Pharmacology, vol. 207, no. 2 Suppl, 2005, pp. 70-6.
Wu D, Cederbaum AI. Oxidative stress mediated toxicity exerted by ethanol-inducible CYP2E1. Toxicol Appl Pharmacol. 2005;207(2 Suppl):70-6.
Wu, D., & Cederbaum, A. I. (2005). Oxidative stress mediated toxicity exerted by ethanol-inducible CYP2E1. Toxicology and Applied Pharmacology, 207(2 Suppl), 70-6.
Wu D, Cederbaum AI. Oxidative Stress Mediated Toxicity Exerted By Ethanol-inducible CYP2E1. Toxicol Appl Pharmacol. 2005 Sep 1;207(2 Suppl):70-6. PubMed PMID: 16019049.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oxidative stress mediated toxicity exerted by ethanol-inducible CYP2E1. AU - Wu,Defeng, AU - Cederbaum,Arthur I, PY - 2004/07/15/received PY - 2005/01/10/revised PY - 2005/01/10/accepted PY - 2005/7/16/pubmed PY - 2008/10/2/medline PY - 2005/7/16/entrez SP - 70 EP - 6 JF - Toxicology and applied pharmacology JO - Toxicol Appl Pharmacol VL - 207 IS - 2 Suppl N2 - Induction of CYP2E1 by ethanol is one of the central pathways by which ethanol generates a state of oxidative stress in hepatocytes. To study the biochemical and toxicological actions of CYP2E1, our laboratory established HepG2 cell lines which constitutively overexpress CYP2E1 and characterized these cells with respect to ethanol toxicity. Addition of ethanol or an unsaturated fatty acid such as arachidonic acid or iron was toxic to the CYP2E1-expressing cells but not control cells. This toxicity was associated with elevated lipid peroxidation and could be prevented by antioxidants and inhibitors of CYP2E1. Apoptosis occurred in the CYP2E1-expressing cells exposed to ethanol, arachidonic acid, or iron. Removal of GSH caused a loss of viability in the CYP2E1-expressing cells even in the absence of added toxin or pro-oxidant. This was associated with mitochondrial damage and decreased mitochondrial membrane potential. Low concentrations of iron and arachidonic acid synergistically interacted with CYP2E1 to produce cell toxicity, suggesting these nutrients may act as priming or sensitizing agents to alcohol-induced liver injury. Surprisingly, CYP2E1-expressing cells had elevated GSH levels, due to transcriptional activation of glutamate cysteine ligase. Similarly, levels of catalase, alpha-, and microsomal glutathione transferase were also increased, suggesting that upregulation of these antioxidant genes may reflect an adaptive mechanism to remove CYP2E1-derived oxidants. Using co-cultures, interaction between CYP2E1-derived diffusible mediators to activate collagen production in hepatic stellate cells was found. While it is likely that several mechanisms contribute to alcohol-induced liver injury, the linkage between CYP2E1-dependent oxidative stress, mitochondrial injury, stellate cell activation, and GSH homeostasis may contribute to the toxic action of ethanol on the liver. HepG2 cell lines overexpressing CYP2E1 may be a valuable model to characterize the biochemical and toxicological properties of CYP2E1. SN - 1096-0333 UR - https://www.unboundmedicine.com/medline/citation/16019049/Oxidative_stress_mediated_toxicity_exerted_by_ethanol_inducible_CYP2E1_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0041-008X(05)00357-1 DB - PRIME DP - Unbound Medicine ER -