Ethanol feeding of micropigs alters methionine metabolism and increases hepatocellular apoptosis and proliferation |
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| Institution: | 1. Department of Pediatric Respiratory Medicine, Wilhelmina Children''s Hospital, University Medical Center, Utrecht University, Utrecht, EA 3584, the Netherlands;2. Regenerative Medicine Utrecht, University Medical Center, Utrecht University, Utrecht, CT 3584, the Netherlands;3. Center for Lysosomal and Metabolic Diseases, Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, GD 3015, the Netherlands;4. Department of Pulmonology, Erasmus MC, University Medical Center, Rotterdam, GD 3015, the Netherlands;5. Haga Teaching Hospital, The Hague, CH 2545, the Netherlands;6. Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, XZ 6525, the Netherlands;7. Maastricht University Medical Center, Maastricht, HX 6229, the Netherlands;8. Amsterdam University Medical Center, location AMC, Amsterdam, AZ 1105, the Netherlands;9. University of Groningen, University Medical Center Groningen, Beatrix Children''s Hospital, Department of Pediatric Pulmonology and Pediatric Allergology, Groningen, the Netherlands;10. University of Groningen, University Medical Center Groningen, Groningen Research Institute for Asthma and COPD (GRIAC), Groningen, the Netherlands;11. Division of Medicinal Chemistry, Vrije Universiteit Amsterdam, Amsterdam, HZ 1081, the Netherlands;12. Centre for Living Technologies, Alliance TU/e, WUR, UU, UMC Utrecht, Princetonlaan 6, Utrecht, CB 3584, the Netherlands |
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| Abstract: | Chronic alcoholism is associated with increased cancer risk that may be related to ethanol-induced alterations in methionine and deoxynucleotide metabolism. These metabolic relationships were studied in micropigs fed diets for 12 months that contained 40% ethanol or cornstarch control with adequate folate. Ethanol feeding altered methionine metabolism without changing mean terminal liver folate levels. After initial equilibration to diet, ethanol feeding significantly increased monthly serum homocysteine levels while reducing serum methionine levels over the time course of the experiment. After 12 months, hepatic methionine synthase activity and the ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH) were significantly reduced in ethanol-fed animals, whereas the ratio of liver deoxyuridine triphosphate (dUTP) to deoxythymidine triphosphate (dTTP) was increased and correlated inversely with methionine synthase activity. These findings were associated with increased frequency of hepatocytes with apoptotic bodies and positivity for proliferating cell nuclear antigen (PCNA) in livers from ethanol-fed minipigs. These studies suggest that chronic ethanol feeding perturbs methionine metabolism by impairment of methionine synthase activity, resulting in deoxynucleoside triphosphate (dNTP) imbalance, increased apoptosis, and regenerative proliferation. These biochemical alterations may provide a promoting environment for carcinogenesis during long-term ethanol exposure. (Hepatology 1996 Mar;23(3):497-505) |
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