0155 GMT November 28, 2020
Colon cancer samples were taken from 281 patients and compared with non-cancerous colon tissue from the same patients.
The researchers found that production of the hormone guanylin was decreased by 100-1,000 times in 85% of the colon cancers tested.
Guanylin is a locally acting hormone - it acts on the same cells it is produced by. The hormone activates a receptor called GUCY2C, which is important for helping skin cells replenish the lining of the gut.
The skin of the gut is replenished about every 3 days. If the signals that replenish the skin are unable to maintain cell division, say the researchers, then it becomes more likely that cell division will be irregular and lead to cancer.
When there are low levels of guanylin, the colon cells produce more GUCY2C receptors to try and catch any possible guanylin signal. However, with no hormone signal to catch, the receptors are unable to maintain the health and normal function of their cells.
An additional finding from the team was that patients over the age of 50 produced much less guanylin in their non-cancerous cells than younger patients. The researchers think this could explain why older people are at such increased risk for colon cancer.
"The fact that the vast majority of cancers stop producing this hormone leads us to believe that guanylin may be driving the growth of the tumors," says senior author Dr. Scott Waldman, chair of the Department of Pharmacology & Experimental Therapeutics and the Samuel MV Hamilton Professor at Thomas Jefferson University.
Waldman says that, if the team's findings are confirmed, "We could prevent colon cancer by giving patients hormone replacement therapy with guanylin."
Next, the team will test whether hormone replacement is a viable therapy to prevent the development or growth of colon cancer in mice. The researchers also want to further understand how guanylin maintains the normal health of colon cells.
Earlier this year, we looked at a study from Washington University School of Medicine in St. Louis, MO, and Vanderbilt University Medical Center in Nashville, TN, which found that a protein - PLAC8 - triggers a change in normal cells in the lining of the colon that accommodates the spread of colon cancer.
Other research in 2014 examined how gut bacteria may provide an "incubating" environment for tumor development. The researchers behind that study found that proteins produced by some gut bacteria actively suppress the DNA repair proteins of cells in the guts. Because the cells are unable to repair normally, an accumulation of mutations in the cells leads to cancer.