• Acetaldehyde;
  • DNA Adducts;
  • Alcohol Dehydrogenase;
  • Hepatocellular Carcinoma;
  • Breast Cancer;
  • N2-Ethyldeoxyguanosine

Background:  We recently reported that exposure of human cells in vitro to acetaldehyde resulted in the activation of the Fanconi anemia–breast cancer susceptibility (FA-BRCA) DNA damage response network.

Methods:  To determine whether intracellular generation of acetaldehyde from ethanol metabolism can cause DNA damage and activate the FA-BRCA network, we engineered HeLa cells to metabolize alcohol by expression of human alcohol dehydrogenase (ADH) 1B.

Results:  Incubation of HeLa-ADH1B cells with ethanol (20 mM) resulted in acetaldehyde accumulation in the media, which was prevented by co-incubation with 4-methyl pyrazole (4-MP), a specific inhibitor of ADH. Ethanol treatment of HeLa-ADH1B cells produced a 4-fold increase in the acetaldehyde–DNA adduct and N2-ethylidene-dGuo and also resulted in the activation of the FA-BRCA DNA damage response network, as indicated by a monoubiquitination of FANCD2 and phosphorylation of BRCA1. Ser 1524 was identified as 1 site of BRCA1 phosphorylation. The increased levels of DNA adducts, FANCD2 monoubiquitination, and BRCA1 phosphorylation were all blocked by 4-MP, indicating that acetaldehyde, rather than ethanol itself, was responsible for all 3 responses. Importantly, the ethanol concentration we used is within the range that can be attained in the human body during social drinking.

Conclusions:  Our results indicate that intracellular metabolism of ethanol to acetaldehyde results in DNA damage, which activates the FA-BRCA DNA damage response network.