In vitro genotoxicity of ethanol and acetaldehyde in human lymphocytes and the gastrointestinal tract mucosa cells.

The influence of ethanol and acetaldehyde on DNA in human lymphocytes, gastric mucosa (GM) and colonic mucosa (CM) was investigated by using the comet assay. All kinds of cells were exposed to ethanol and acetaldehyde in two regimens: the cells were incubated with either chemical and analysed or they were exposed first to ethanol, washed and then exposed to acetaldehyde and analysed. Lymphocytes were exposed to ethanol at final concentrations of 30 mM and acetaldehyde at 3 mM. GM cells were incubated with ethanol at 1 M and acetaldehyde at 100 mM. CM cells were exposed to ethanol at 10 mM and acetaldehyde at 100 mM. In combined exposure, the cells were subsequently exposed to ethanol and acetaldehyde at all combination of the concentrations of the agents. Ethanol caused DNA strand breaks, which were repaired during 4 hr, except when this agent was applied in GM cells at a concentration of 1 M. A dose-dependent decrease in the tail moment of all types of acetaldehyde-treated cells was observed. Similar results were obtained when a recognized DNA crosslinking agent, formaldehyde, was used. These results suggest that acetaldehyde may form crosslinks with DNA. These crosslinks were poorly repaired. CM cells showed the highest sensitivity of all cell types to ethanol than lymphocytes and GM cells. There were no differences in the sensitivity to acetaldehyde of all the cell types. Our results clearly indicate that ethanol and acetaldehyde can contribute to cancers of the digestive tract.