A recent study completed by the Medical Research Council (MRC) Laboratory of Molecular Biology in Cambridge suggests a novel reason for why alcohol consumption increases the risk of cancer. In a study published in Nature on 3 January 2018, the Cancer Research UK-funded experiment found that alcohol consumption causes DNA damage in stem cells. In particular, the DNA of haematopoietic stem cells (blood stem cells) are adversely affected by alcohol consumption.
Previous studies that have investigated the carcinogenic effects of alcohol used cell cultures for their experiments. The experiment conducted by the MRC laboratory adopted a novel approach and exposed live mice instead of cultures to ethanol. After chromosome analysis and DNA sequencing of the mice’s genetic information, the team noticed permanent chromosome alterations in the blood stem cells. In particular, the acetaldehyde produced by the body upon consuming alcohol breaks the double-stranded DNA and causes chromosome rearrangements. These mutations increase the risk of cancer because the stem cells become faulty.
The MRC laboratory experiment also observed the role of the enzyme aldehyde dehydrogenase (ALDH) in the body’s response to alcohol. They noticed that mice lacking a functioning ALDH enzyme had four times as much DNA damage as those who did. This confirms our understanding that ALDH is one way the body mitigates the effects of alcohol; ALDH converts acetaldehyde into acetate, which the body uses as energy.
The insight into ALDH’s function in the body compliments our current understanding of the enzyme. For example, a large portion of South East Asians, who on average have lower alcohol tolerances, lack functional versions of ALDH enzymes. This study may also suggest that, based off of one’s inherited ability to produce ALDH enzymes, some individuals may be more prone to the carcinogenic effects of alcohol than others.
Lastly, the study did recognize that cells have DNA repair systems. However, not everyone carries a seamless DNA repair system, as they can often be lost due to chance mutations. Further, with substantial enough alcohol exposure, these systems may fail (as they did with the mice) and result in DNA damage.
The study did not conclude whether such DNA damage was hereditary, as the lab only looked at blood stem cells. Nevertheless, Cancer Research UK has publicized this study as a compelling reason to control alcohol intake and consume in moderation.