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World J Gastroenterol. Oct 7, 2007; 13(37): 4955-4959
Published online Oct 7, 2007. doi: 10.3748/wjg.v13.i37.4955
Effects of ethanol on hepatic cellular replication and cell cycle progression
Dahn L Clemens
Dahn L Clemens, Department of Internal Medicine, University of Nebraska Medical Center and Veterans Affairs Medical Center, Omaha, Nebraska 68105, United States
Author contributions: All authors contributed equally to the work.
Supported by the National Institutes of Health Grant RO1 AA11291 and the Department of Veterans Affairs
Correspondence to: Dahn L Clemens, PhD, Department of Internal Medicine, University of Nebraska Medical Center and Veterans Affairs Medical Center, Omaha, Nebraska 68105, United States. dclemens@unmc.edu
Telephone: +1-402-3468800-3738 Fax: +1-402-4490604
Received: June 30, 2007
Revised: July 17, 2007
Accepted: July 26, 2007
Published online: October 7, 2007
Abstract

Ethanol is a hepatotoxin. It appears that the liver is the target of ethanol induced toxicity primarily because it is the major site of ethanol metabolism. Metabolism of ethanol results in a number of biochemical changes that are thought to mediate the toxicity associated with ethanol abuse. These include the production of acetaldehyde and reactive oxygen species, as well as an accumulation of nicotinamide adenine dinucleotide (NADH). These biochemical changes are associated with the accumulation of fat and mitochondrial dysfunction in the liver. If these changes are severe enough they can themselves cause hepatotoxicity, or they can sensitize the liver to more severe damage by other hepatotoxins. Whether liver damage is the result of ethanol metabolism or some other hepatotoxin, recovery of the liver from damage requires replacement of cells that have been destroyed. It is now apparent that ethanol metabolism not only causes hepatotoxicity but also impairs the replication of normal hepatocytes. This impairment has been shown to occur at both the G1/S, and the G2/M transitions of the cell cycle. These impairments may be the result of activation of the checkpoint kinases, which can mediate cell cycle arrest at both of these transitions. Conversely, because ethanol metabolism results in a number of biochemical changes, there may be a number of mechanisms by which ethanol metabolism impairs cellular replication. It is the goal of this article to review the mechanisms by which ethanol metabolism mediates impairment of hepatic replication.

Keywords: Cyclin-dependent kinases; Cell cycle; Liver regeneration; Ethanol metabolism; Acetaldehyde; Alcoholic liver disease