Activity of Class I, II, III, and IV Alcohol Dehydrogenase (ADH) Isoenzymes and Aldehyde Dehydrogenase (ALDH) in Esophageal Cancer

Background/Aims Ethanol consumption is associated with an increased risk of esophageal cancer. The carcinogenic compound is acetaldehyde, the product of ethanol metabolism. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the main enzymes involved in ethanol metabolism, which leads to generation of acetaldehyde. In this study the activity of ADH isoenzymes and ALDH in esophageal cancer were compared with the activity in normal tissue. Methods For measurement of the activity of class I and II ADH isoenzymes and ALDH activity fluorimetric methods were employed. Total ADH activity and activity of class III and IV isoenzymes was measured by the photometric method. Samples were taken from 59 esophageal cancer patients (27 adenocarcinoma, 32 squamous cell cancer). Results The total activity of ADH and activity of class IV ADH were significantly higher in cancer cells than in healthy tissues. The other tested classes of ADH showed a tendency toward higher activity in cancer than in normal cells. Differences between the activity of enzymes of drinkers and non-drinkers in both cancer and healthy tissue were not significant. Conclusion Increased ADH IV activity may be a factor intensifying carcinogenesis, because of the increased ability to form acetaldehyde from ethanol.