The mice were given diluted alcohol, known as ethanol. Following this a
chromosomal analysis and
were performed to analyze the changes
in the mice DNA.
‘In individuals with deficiency or mutated aldehyde dehydrogenase enzyme, the DNA damage increases up to four times.’
When alcohol is consumed and processed by the body, acetaldehyde, a harmful
chemical is produced as a result. This, the study has found can break DNA bonds
within blood stem cells. Breaking
of bonds can result in rearrangement of chromosomes and alteration of the
genetic material, causing permanent damage to cells. These altered stem cells
can lead to cancer if the basic properties are altered.
The study shows how alcohol based DNA changes can increase
the risk for 7 different types of cancer including breast
and bowel cancer
which are very common.
role of aldehyde dehydrogenases
Professor Ketan Patel, lead author of the study said:
"Some cancers develop due to DNA damage in stem cells. While some damage
occurs by chance, our findings suggest that drinking
can increase the risk of this damage."
A class of enzymes called aldehyde dehydrogenases (ALDH) is
the first line of defence to protect the body from the negative effects of
alcohol. They break down acetaldehyde into acetates which can be used up by
cells as a source of energy.
However millions of people, especially those in South East
Asia lack this class of enzymes or have non-functional copies as a result of
mutation. In these individuals, regular consumption of alcohol causes problems
as the harmful by-product cannot be broken down due to lack of enzymes.
In the study, when mice that had mutated ALDH enzyme were
given alcohol, there were four times as much DNA damage in their cells compared
to mice with functioning enzyme.
Professor Patel concludes, "Our study highlights that
not being able to process alcohol effectively can lead to an even higher risk
of alcohol-related DNA damage and therefore certain cancers
. But it's
important to remember that alcohol clearance and DNA repair systems are not
perfect and alcohol can still cause cancer in different ways, even in people
whose defence mechanisms are intact."
- Juan I. Garaycoechea, Gerry P. Crossan, Frédéric Langevin, Lee Mulderrig, Sandra Louzada, Fentang Yang, Guillaume Guilbaud, Naomi Park, Sophie Roerink, Serena Nik-Zainal, Michael R. Stratton, Ketan J. Patel. Alcohol and endogenous aldehydes damage chromosomes and mutate stem cells. Nature, 2018; DOI: 10.1038/nature25154