Fat Gene Linked to Colon Cancer

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Gene for Fat Hormone Affects Colon Cancer Risk

By Daniel J. DeNoon
WebMD Health News

Reviewed By Louise Chang, MD

Sept. 30, 2008 -- A fat hormone gene is linked to colon cancer, researchers find.

The finding provides part of the answer to a big question: What triggers colon cancer?

To get at this question, Boris Pasche, MD, PhD, and colleagues followed a trail of clues that implicates adiponectin, a hormone made only by fat cells.

• Colon cancer cells have more adiponectin receptors than do normal gut cells.
• People with the highest adiponectin levels have a 47% lower risk of colon cancer than do people with the lowest adiponectin levels.
• Obese people have decreased adiponectin levels.
• Obese people have an increased risk of colon cancer.

The researchers looked at five common variants of the adiponectin gene and five common variants of the gene for the adiponectin receptor.

They first analyzed adiponectin genes from about 1,100 people of Ashkenazi Jewish ancestry, including 441 colon cancer patients. This population is at particularly high risk of colon cancer. Three adiponectin gene variants, and one adiponectin receptor gene variant, affected colon cancer risk.

The researchers then analyzed the same gene variants in 199 colon cancer patients and 199 matched controls in mixed-ethnicity Chicago-area residents. Only one variant of the adiponectin gene was linked to colon cancer, but it was the same as one of the variants in the first study and reduced the risk of colon cancer by the same amount.

When the studies were combined, the gene variant cut colon cancer by 27%.

"Now, for the first time, we see a gene in these fat cells is linked to colon cancer," Pasche says.

Evadnie Rampersaud, PhD, research assistant professor at the University of Miami's Institute for Human Genomics, says it's an important finding. Rampersaud was not involved in the Pasche study.

"What is unique is this is the first time anybody has identified a genetic variation, a location within the adiponectin gene, that they can link to colon cancer," Rampersaud tells WebMD. "That is pretty amazing."

What excites Pasche and Rampersaud isn't the specific gene variant linked to colon cancer. What's much more interesting is that this variant points to a specific region of the adiponectin gene that affects colon cancer -- and, very likely, other types of cancer as well.

"This opens the door for more research," Pasche says.

Pasche and colleagues report their findings in the Oct. 1 issue of The  Journal of the American Medical Association.

SOURCES: Kaklamani, V.G. TheJournal of the American Medical Association, Oct. 1, 2008; vol 300: pp 1523-1531. Boris Pasche, MD, PhD, director, division of hematology/oncology; associate director for translational research, Comprehensive Cancer Center, University of Alabama at Birmingham. Evadnie Rampersaud, PhD, research assistant professor, Miami Institute for Human Genomics, University of Miami Miller School of Medicine.

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