TY - JOUR
T1 - Proteasome inhibition potentiates CYP2E1-mediated toxicity in HepG2 cells
AU - Pérez, María José
AU - Cederbaum, Arthur I.
N1 - Funding Information:
Abbreviations: ROS, reactive oxygen species; AA, arachidonic acid; BSO, buthionine sulfoximine; GSH, glutathione; PUFA, polyunsaturated fatty acids; MEM, minimal essential medium; Fe-NTA, Fe-nitrilotriacetic acid; MTT, 3(4,5-dimethylthiazole-2-yl) 2,5-diphenyltetrazolium bromide; MDA, malondialdehyde; TBARS, thiobarbituric acid reactive substances; PI, propidium iodide; Rh123, rhodamine 123; MG115, Cbz-leu-leu-norvalinal; MG132, Cbz-leu-leu-leucinal; ALLN, acetyl-leu-leu-norleucinal. From the Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, NY. Received January 14, 2003; accepted March 9, 2003. Supported by USPHS grants AA07311 and AA03312 from The National Institute on Alcohol Abuse and Alcoholism. Address reprint requests to: Arthur I. Cederbaum, Ph.D., Department of Pharmacology and Biological Chemistry, Box 1603, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029. E-mail: [email protected]; fax: 212-996-7214. Copyright © 2003 by the American Association for the Study of Liver Diseases. 0270-9139/03/3706-0025$30.00/0 doi:10.1053/jhep.2003.50228
PY - 2003/6/1
Y1 - 2003/6/1
N2 - Chronic ethanol consumption causes increased oxidative damage in the liver. Induction of CYP2E1 is one pathway involved in how ethanol produces oxidative stress. Ethanol can cause protein accumulation, decreased proteolysis, and decreased proteasome activity. The objective of this study was to investigate the effect of inhibition of the proteasome activity on CYP2E1-dependent toxicity. HepG2 cells over-expressing CYP2E1 (E47 cells) were treated with arachidonic acid (AA) plus iron, agents important in development of alcoholic liver injury and which are toxic to E47 cells by a mechanism dependent on CYP2E1, oxidative stress, and lipid peroxidation. Addition of various proteasome inhibitors was associated with significant potentiation of the loss of cell viability caused by AA plus iron. Potentiation of toxicity was associated with increased oxidative damage as reflected by an increase in lipid peroxidation and accumulation of oxidized and nitrated proteins in E47 cells and an enhanced decline in mitochondrial membrane potential. Antioxidants prevented the loss of viability and the potentiation of this loss of viability by proteasome inhibition. CYP2E1 levels were elevated about 3-fold by the proteasome inhibitors. Inhibition of proteasome activity also potentiated toxicity of AA alone and toxicity after treatment to remove glutathione (GSH). Similar results were found in hepatocytes from pyrazole-treated rats with high levels of CYP2E 1. In conclusion, proteasome activity plays an important role in modulating CYP2E1-mediated toxicity in HepG2 cells by regulating CYP2E1 levels and by removal of oxidized proteins. Such interactions may be important in CYP2E1-catalyzed toxicity of hepatotoxins and in alcohol-induced liver injury.
AB - Chronic ethanol consumption causes increased oxidative damage in the liver. Induction of CYP2E1 is one pathway involved in how ethanol produces oxidative stress. Ethanol can cause protein accumulation, decreased proteolysis, and decreased proteasome activity. The objective of this study was to investigate the effect of inhibition of the proteasome activity on CYP2E1-dependent toxicity. HepG2 cells over-expressing CYP2E1 (E47 cells) were treated with arachidonic acid (AA) plus iron, agents important in development of alcoholic liver injury and which are toxic to E47 cells by a mechanism dependent on CYP2E1, oxidative stress, and lipid peroxidation. Addition of various proteasome inhibitors was associated with significant potentiation of the loss of cell viability caused by AA plus iron. Potentiation of toxicity was associated with increased oxidative damage as reflected by an increase in lipid peroxidation and accumulation of oxidized and nitrated proteins in E47 cells and an enhanced decline in mitochondrial membrane potential. Antioxidants prevented the loss of viability and the potentiation of this loss of viability by proteasome inhibition. CYP2E1 levels were elevated about 3-fold by the proteasome inhibitors. Inhibition of proteasome activity also potentiated toxicity of AA alone and toxicity after treatment to remove glutathione (GSH). Similar results were found in hepatocytes from pyrazole-treated rats with high levels of CYP2E 1. In conclusion, proteasome activity plays an important role in modulating CYP2E1-mediated toxicity in HepG2 cells by regulating CYP2E1 levels and by removal of oxidized proteins. Such interactions may be important in CYP2E1-catalyzed toxicity of hepatotoxins and in alcohol-induced liver injury.
UR - http://www.scopus.com/inward/record.url?scp=0038580392&partnerID=8YFLogxK
U2 - 10.1053/jhep.2003.50228
DO - 10.1053/jhep.2003.50228
M3 - Article
C2 - 12774019
AN - SCOPUS:0038580392
SN - 0270-9139
VL - 37
SP - 1395
EP - 1404
JO - Hepatology
JF - Hepatology
IS - 6
ER -