title: Elevated glutathione level does not protect against chronic alcohol mediated apoptosis in recombinant human hepatoma cell line VL-17A over-expressing alcohol metabolizing enzymes--alcohol dehydrogenase and Cytochrome P450 2E1.
abstract: Chronic consumption of alcohol leads to liver injury. Ethanol-inducible Cytochrome P450 2E1 (CYP2E1) plays a critical role in alcohol mediated oxidative stress due to its ability to metabolize ethanol. In the present study, using the recombinant human hepatoma cell line VL-17A that over-expresses the alcohol metabolizing enzymes-alcohol dehydrogenase (ADH) and CYP2E1; and control HepG2 cells, the mechanism and mode of cell death due to chronic ethanol exposure were studied. Untreated VL-17A cells exhibited apoptosis and oxidative stress when compared with untreated HepG2 cells. Chronic alcohol exposure, i.e., 100 mM ethanol treatment for 72 h caused a significant decrease in viability (47%) in VL-17A cells but not in HepG2 cells. Chronic ethanol mediated cell death in VL-17A cells was predominantly apoptotic, with increased oxidative stress as the underlying mechanism. Chronic ethanol exposure of VL-17A cells resulted in 1.1- to 2.5-fold increased levels of ADH and CYP2E1. Interestingly, the level of the antioxidant GSH was found to be 3-fold upregulated in VL-17A cells treated with ethanol, which may be a metabolic adaptation to the persistent and overwhelming oxidative stress. In conclusion, the increased GSH level may not be sufficient enough to protect VL-17A cells from chronic alcohol mediated oxidative stress and resultant apoptosis.
authors.affiliation: Life Science Division, AU-KBC Research Centre, MIT Campus of Anna University, Chromepet, Chennai 600 044, India.
authors.forename: Karthikeyan
authors.initials: K
authors.lastname: Chandrasekaran
authors.forename: Kavitha
authors.initials: K
authors.lastname: Swaminathan
authors.forename: S Mathan
authors.initials: SM
authors.lastname: Kumar
authors.forename: Suvro
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Dahn L
authors.initials: DL
authors.lastname: Clemens
authors.forename: Aparajita
authors.initials: A
authors.lastname: Dey
mesh_terms: D000426:Alcohol Dehydrogenase / Q000378:metabolism; D000428:Alcohol Drinking / Q000009:adverse effects; D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D000431:Ethanol / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D005978:Glutathione / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000431:Ethanol; D000426:Alcohol Dehydrogenase; D019392:Cytochrome P-450 CYP2E1; D005978:Glutathione