Wednesday, January 20, 2016

Researchers investigate why obesity can trigger bowel cancer



"Excess calories 'turn off a hormone in the intestine that blocks colon cancer'," the Mail Online reports.
Obesity is a known risk factor for bowel cancer (also known as colorectal cancer). There is evidence that a diet rich in processed meats, which contain the potentially cacogenic compound nitrates, increases bowel cancer risk. However, it is unclear why other high-calorie diets also increase risk.
This latest study, conducted in genetically engineered mice, found that obesity caused by a diet rich in fats or carbohydrates "silenced" a hormone called guanylin. This, in turn, led to the turning off of a receptor called guanylyl cyclase C (GUCY2C) found on cells that line the bowel. Receptors are specialised structures designed to respond to specific chemical signals.
Turning off this receptor was associated with tumour growth, as the GUCY2C receptor, when working properly, is designed to prevent abnormal cell growth. Further study confirmed this by showing that using a drug to increase production of guanylin reversed the effects of the high-calorie diet and prevented tumour growth.
The obvious question is: could a similar drug be effective in obese humans thought to be at high risk of developing bowel cancer? The simple answer is: we just don't know yet.
It is unwise to assume that the results of an animal study will transfer over to people; we are not biologically identical.
However, the study does provide a route – looking at ways to activate the GUCY2C receptor in humans – for further, hopefully fruitful, research in the area.

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