Alcohol consumption permanently damages DNA in stem cells, which in turn increases the risk of developing cancer, warns a study led by a scientist of Indian origin.
Much of the previous research that analyzes the precise ways in which alcohol causes cancer has been done in cell cultures. However, in the new study, the researchers used mice to show how exposure to alcohol leads to permanent genetic damage.
Scientists at the MRC Molecular Biology Laboratory at the University of Cambridge in the United Kingdom gave dilute alcohol, chemically known as ethanol, to mice. They then used chromosomal analysis and DNA sequencing to examine the genetic damage caused by acetaldehyde, a harmful chemical that occurs when the body processes alcohol. The researchers discovered that acetaldehyde can break down and damage the DNA inside the blood stem cells, causing the rearrangement of the chromosomes and permanent alteration of the DNA sequences within these cells.
“Some cancers develop because of DNA damage in the stem cells,” said Professor Ketan Patel of the Molecular Biology Laboratory at MRC. “While some damage happens by chance, our findings suggest that drinking alcohol can increase the risk of this damage,” said Patel, lead author of the study published in the journal Nature.
It is important to understand how the DNA model within the stem cells is damaged because when healthy stem cells become defective, they can lead to cancer, the researchers said. The new findings help us understand how alcohol consumption increases the risk of developing seven types of cancer, including common types such as breast and bowel cancer, they said.
The study also examined how the body tries to protect itself from the harm caused by alcohol. The first line of defense is a family of enzymes called aldehyde dehydrogenases (ALDH). These enzymes break down the harmful acetaldehyde into acetate, which our cells can use as an energy source. Around the world, millions of people, particularly those in Southeast Asia, lack these enzymes or have defective versions of them, according to the researchers. When they drink, acetaldehyde builds up and causes a reddened complexion, and it also causes them discomfort, they said.
In the study, when mice lacking the critical ALDH enzyme (ALDH2) were given alcohol, four times more DNA damage occurred in their cells compared to mice with the fully functional ALDH2 enzyme. The second line of defense used by cells is a variety of DNA repair systems that, most of the time, allow them to repair and reverse different types of DNA damage.
However, they do not always work and some people carry mutations, which means that their cells can not carry out these repairs effectively. “Our study highlights that not being able to process alcohol effectively can lead to an even greater risk of alcohol-related harm and, therefore, certain cancers,” Patel said. “But it is important to remember that systems of alcohol elimination and DNA repair are not perfect and alcohol can cause cancer in different ways, even in people whose defense mechanisms are intact,” he added.