Navigation Links
Colon cancer shuts down receptor that could shut it down
Date:4/13/2009

AUGUSTA, Ga. Though a high-fiber diet has long been considered good for you and beneficial in staving off colon cancer, Medical College of Georgia researchers have discovered a reason why: roughage activates a receptor with cancer-killing potential.

Researchers report in the April issue of Cancer Research that the GPR109A receptor is activated by butyrate, a metabolite produced by fiber-eating bacteria in the colon. The receptor puts a double-whammy on cancer by sending signals that trigger cell death, or apoptosis, and shutting down a protein that causes inflammation, a precursor to cancer.

"We know the receptor is silenced in cancer but it's not like the gene goes away," says Dr. Vadivel Ganapathy, corresponding author and chair of the Department of Biochemistry and Molecular Biology in the MCG School of Medicine.

Cancer shuts down the receptor by chemically modifying its gene through a process called DNA methylation. It's a typical MO for cancer to turn genes off to suit its purpose which is why DNA methylation inhibitors already are under study for a variety of cancers.

But cancer patients likely also need something to ensure the receptor gets activated by butyrate, such as eating more roughage or, more likely, getting mega doses of butyrate or a compound with similar properties, Dr. Ganapathy says.

One of those activators, niacin, a B-complex vitamin, led to his discovery of the relationship between butyrate and GPR109A. Research teams at GlaxoSmithKline and the University of Heidelberg, Germany in 2003 showed cloned GPR109A mediated the protective cardiovascular effect of niacin, but was activated only if niacin levels in the blood were 1,000 times normal levels. That got the German research team to search for alternative activators of the receptor, resulting in identification of beta-hydroxybutyrate as a natural receptor activator. The same study showed butyrate also could activate the receptor but with much less potency. That got Dr. Ganapathy thinking about a place where butyrate levels were already high the colon which led to his discovery that the receptor was also on colon cells.

Butyrate plays other protective roles in colon cancer. In 2004, MCG researchers identified a gene, SLC5A8, that transports butyrate inside cells where it inhibits the enzyme HDAC, which gets upregulated in cancer to produce the uncontrolled cell growth that is a disease hallmark.

"If you block HDAC, you can kill the cancer cell," Dr. Ganapathy says.

Several synthetic HDAC inhibitors are under study for a variety of cancers at institutions such as the MCG Cancer Center. Unfortunately, just like the newly found GPR109A receptor, cancer also silences the SLC5A8 butyrate transporter. In his current study, the researcher found the receptor was silenced in 15 of 18 colon cancer patients.

"Colon cancer does not want butyrate produced by bacteria to come inside so it silences the transporter. It also does no want butyrate to act on the cell from the outside so it silences the receptor," Dr. Ganapathy says. "It does not want to have anything to do with butyrate."

Because the compounds that reactivate the receptor also reactivate the transporter, finding a way to mitigate cancer's attempts to silence the genes would create a two-prong attack against the cancer.

Mega doses of butyrate reportedly taste bad. But Dr. Ganapathy believes taking large amounts of niacin, something many patients already do for high cholesterol, is a good substitute. In fact, he wants to move ahead with clinical trials that compare the course of colon cancer patients who eat a high fiber diet or receive butyrate or niacin therapy along with taking DNA methylation inhibitors that keep GPR109A open for business.

He also wants to determine if his theory that inflammation also suppresses the receptor holds true. "We think receptor activation by butyrate suppresses inflammation, thereby suppressing progression of inflamed cells into cancer cells." If he's correct, targeting the receptor also may provide a new treatment for inflammatory bowel disease.


'/>"/>

Contact: Toni Baker
tbaker@mcg.edu
706-721-4421
Medical College of Georgia
Source:Eurekalert  

Related medicine news :

1. Diet high in meat, fat and refined grains linked to risk for colon cancer recurrence, death
2. Coloring Compound in Fruits, Veggies May Cut Colon Cancer Risk
3. Gastroenterology sets standards for CT colonography
4. Experts Compare Colon Cancer Treatment Outcomes
5. Doctors Office Outreach Boosts Colon Cancer Screening
6. Jefferson researchers find personalized interventions key to improving colon cancer screening rates
7. Molecular profiling can accurately predict survival in colon cancer patients
8. Study Links Coronary Disease, Colon Cancer
9. Fecal Blood Tests Effective at Spotting Colon Cancer
10. Produce for Better Health Foundation Releases Statement on Study Saying Fruit & Vegetable Consumption Not Strongly Associated With Colon Cancer Risk
11. Study makes progress in zoning in on biomarkers for better colon cancer treatment
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Colon cancer shuts down receptor that could shut it down
(Date:6/24/2016)... ... June 24, 2016 , ... Marcy was in a crisis. Her son James, eight, was out ... family verbally and physically. , “When something upset him, he couldn’t control his emotions,” remembers ... would throw rocks at my other children and say he was going to kill them. ...
(Date:6/24/2016)... MIAMI, Fla. (PRWEB) , ... June 24, 2016 , ... ... Florida Trend magazine’s 2016 Legal Elite. The attorneys chosen by their peers for this ... of Florida. , Seven Greenberg Traurig Shareholders received special honors as members of this ...
(Date:6/24/2016)... ... June 24, 2016 , ... Comfort Keepers® of San ... Society and the Road To Recovery® program to drive cancer patients to and from ... adults to ensure the highest quality of life and ongoing independence. Getting to ...
(Date:6/24/2016)... ... ... People across the U.S. are sharpening their pencils and honing their writing ... which patients and their families pay tribute to a genetic counselor by nominating him ... Genetic Counselors (NSGC) Annual Education Conference (AEC) this September. , In April, Genome ...
(Date:6/24/2016)... ... June 24, 2016 , ... The ... recognize Dr. Barry M. Weintraub as a prominent plastic surgeon and the network’s ... the world, and the most handsome men, look naturally attractive. Plastic surgery should ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... , June 24, 2016  Arkis BioSciences, ... less invasive and more durable cerebrospinal fluid treatments, ... funding.  The Series-A funding is led by Innova ... Fund, and other private investors.  Arkis, new financing ... instrumentation and the market release of its in-licensed ...
(Date:6/23/2016)...  In a startling report released today, National Safety Council ... a comprehensive, proven plan to eliminate prescription opioid overdoses. ... states are tackling the worst drug crisis in recorded U.S. history, ... Kentucky , New Mexico , ... the 28 failing states, three – Michigan , ...
(Date:6/23/2016)... Bracket , a leading clinical trial technology and specialty ... Bracket eCOA (SM) 6.0, at the 52 nd ... in Philadelphia , Pennsylvania.  A demonstration of ... its kind to fully integrate with RTSM, will be held ... a flexible platform for electronic clinical outcomes assessments that is ...
Breaking Medicine Technology: