September 16, 2011

Alcohol Linked to Breast and Liver Cancer

(Ivanhoe Newswire) -- Next time you reach for a drink, you may need to consider side effects other than a rough morning. A new study that will be published in the December 2011 issue of Alcoholism: Clinical & Experimental Research has established a link between alcohol metabolism and DNA damage that may cause breast and liver cancers.

Alcohol is known to be carcinogenic to humans in the upper aero digestive tract, liver, colon, and the female breast.

"Although the link between drinking alcohol and certain types of cancers was first established in the 1980s, the existence of such a relationship did not prove that alcohol itself caused the cancers," Phillip J. Brooks, program director in the Division of Metabolism and Health Effects at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) was quoted as saying.

"More recent evidence, however, has confirmed that alcohol - more specifically, ethanol - is carcinogenic to humans at several body sites," Brooks added.

When alcohol is metabolized in the human body, it is converted to acetaldehyde, a chemical that is structurally similar to formaldehyde. Acetaldehyde can cause DNA damage, trigger chromosomal abnormalities in cell culture studies, and act as an animal carcinogen.

"In most people, acetaldehyde is quickly converted to acetate, a relatively harmless substance, by an enzyme called aldehyde dehydrogenase 2 (ALDH2). However, approximately 30 percent of East Asians are unable to metabolize alcohol to acetate due to a genetic variant in the ALDH2 gene, and have a greatly elevated risk of esophageal cancer from alcohol drinking," Brooks was quoted as saying.

The study exposed human cells to alcohol concentrations equivalent to levels found in the body during social drinking. The cells were engineered to metabolize alcohol into acetaldehyde by an enzyme found in human liver and breast tissue.

When cells divide they replicate DNA. "However, when the DNA is damaged, replication cannot continue," Brooks explained, "The Fanconic anemia-breast cancer (FA-BRCA) network is a collection of proteins that responds to DNA damage by coordinating DNA repair or helping the replication machinery to bypass the DNA damage, thereby allowing replication to continue. In the human body, the FA-BRCA network seems to be particularly important in protecting against breast cancer."

"We found that the cells converted the alcohol into acetaldehyde, and that this resulted in increased levels of acetaldehyde-DNA damage," Brooks was quoted as saying. He added that the cells also activated the FA-BRCA network.

"While our work shows acetaldehyde plays a role in alcohol related liver and breast cancer, more studies in animals and humans will be necessary to prove such a role," Brooks stated.

He added that the relationship between alcohol metabolism, the FA-BRCA network, and human health will likely be a very important area of study in the future.

SOURCE: Alcoholism: Clinical & Experimental Research, published December 2011