DNA adductomics for the investigation of alcohol-related DNA damage

Silvia BALBO, University of Minnesota, United States

1 Masonic Cancer Center, University of Minnesota, Minneapolis MN, USA

Alcohol consumption increases the risk of head and neck and esophageal cancers. Despite this clear association, the underlying mechanisms of alcohol-induced carcinogenesis remain unclear. Alcohol–derived acetaldehyde seems to play a role in this process. Acetaldehyde is a genotoxic and carcinogenic compound that induces DNA modifications. If not eliminated or repaired, these modifications can result in miscoding events that can lead to misregulation of normal cellular growth control mechanisms and ultimately may result in cancer formation. Traditionally, the standard LC-MS methodology used for DNA adduct measurement focuses on the investigation of small numbers of anticipated DNA adducts based on a priori assumptions regarding their formation from specific exposures or chemicals. This approach does not account for the complexity of in vivo DNA adduct formation resulting from endogenous sources such as oxidative stress, lipid peroxidation or aberrant metabolism, or as a result of exposure to complex mixtures of chemicals which cannot be completely anticipated or predicted. To address this limitation, we have developed a high resolution/accurate mass data dependent-constant neutral loss-MS3 methodology for DNA adductomics using ion trap-orbital trap technology, to screen for all DNA modifications simultaneously. We have successfully tested our method on mixtures of standards and applied it to oral cell DNA samples collected from individuals exposed to 0.07% blood alcohol level and compared to controls. Our method allowed for the detection of the expected DNA adducts resulting from acetaldehyde but also of a number of unknown DNA adducts that have not been previously identified and investigated, confirming the ability of our DNA adductomic approach to characterize the DNA damage deriving from alcohol exposure. Our comprehensive DNA adductomic approach contributes to the development of new tools needed to investigate alcohol-related carcinogenesis, elucidate its mechanisms and ultimately generate instruments to help prevention.