Over 700,000 people worldwide died from colorectal cancer in 2010, up from 500,000 in 1990, making it the fourth leading cause of cancer death behind lung, stomach and liver.
Remarkably, your household bottle of aspirin – in addition to relieving the common headache – protects against colorectal cancer based on several clinical trials over the past few decades. Though its effect is clear, how exactly aspirin prevents colon cancer has remained murky.
Who cares how it works as long as it saves lives, right?
Well, it turns out that long-term daily use of aspirin carries risks of internal bleeding of the stomach and brain, kidney failure, and certain types of strokes. So unraveling what exactly aspirin does to fend off tumors is an important step to finding new drugs with fewer side effects.
Earlier this week, scientists at University of Pittsburgh Cancer Institute (UPCI) reported that they’ve unlocked the secrets of aspirin’s tumor-killing powers. In their study, published in the Proceedings of the National Academy of Sciences (PNAS), the UPCI team shows that aspirin prevents colon cancer by orchestrating the death of stem cells in the intestine that carry a dangerous mutation.
Most colorectal cancers initially crop up with a mutation in a gene called APC. The APC protein is a so-called tumor suppressor, which acts to keep a lid on any uncontrolled cell division, an early step to tumor growth. So a bad APC gene leads to a faulty APC protein and, in turn, the potential for normal intestinal cells to become cancerous. The intestine has a rich source of stem cells, which are particularly vulnerable to this mutation since stem cells already possess the ability for unlimited cell growth.
The research team compared colorectal tumor samples from patients who had taken aspirin to those who had not. Using these samples in animal studies, the researchers showed that aspirin triggers cell suicide in intestinal stem cells that carry the APC mutation, effectively killing off the cells with the potential of feeding tumor growth. Healthy intestinal cells, on the other hand, are left unscathed by aspirin.
With this important discovery of cell suicide, or programmed cell death in scientific jargon, as the instigator of aspirin’s ability to prevent colon cancer, the research team finds themselves at an exciting new starting line to find drugs for cancer patients with less harmful side effects.
As the senior author Lin Zhang states in a university press release:
“We want to use our new understanding of this mechanism as a starting point to design better drugs and effective cancer prevention strategies for those at high risk of colon cancer.”