Pepper Compound Effective in Fighting Gut Tumors

A compound in chili pepper can reduce risk of colorectal tumors, a new study suggests.

According to researchers at the University of California, San Diego School of Medicine, dietary capsaicin - a compound in peppers - can activate a receptor in the cells lining the intestines. Chronic activation of these ion-channels or receptors leads to lower risk of colorectal tumors.

TRPV1 - the receptor used in the study - was originally discovered in sensory neurons. The ion channel detects heat, acidity and spicy chemicals in the environment.

"These are all potentially harmful stimuli to cells," said Eyal Raz, MD, professor of Medicine and senior author of the study, according to a news release. "Thus, TRPV1 was quickly described as a molecular 'pain receptor.' This can be considered to be its conventional function, which all takes place in the nervous system."

Now, researchers have found that the epithelial cells of the intestines also express TPRV1. In these cells, TPRV1 is activated by epidermal growth factor receptor or EGFR. The cell lining of the intestines is replaced every four to six days. EGFR is associated with cell proliferation in the intestines.

According to researchers, unchecked activity of EGFR can lead to excess cell proliferation, which could lead to tumor formation.

The team found that TRPV1, which is actually activated by EGFR, initiates a negative feedback and turns off the activity of EGFR, meaning that with no TRPV1 the cells would continue to grow and spread. This is exactly what happened in test mice that were devoid of TRPV1. The researchers found that these mice had higher-than-normal rates of intestinal tumor growths

"A basic level of EGFR activity is required to maintain the normal cell turnover in the gut," said Petrus de Jong, MD, first author of the study. "However, if EGFR signaling is left unrestrained, the risk of sporadic tumor development increases."

The researchers maintain that currently there is no evidence that directly links TRPV1 with tumor growth. The team said that more research is needed to establish this association.

Capsaicin is already used in topical pain-relievers. The irritants in capsaicin overwhelm the neurons that detect pain, leaving them unable to send pain signals to the brain. Several studies have shown that capsaicin is somewhat effective in reducing pain in people suffering from cancers, mouth sores or diabetic neuropathy.

The team also administered capsaicin to mice models that were prone to developing gastrointestinal tract tumors. Scientists found that several tumors were suppressed in the mice and the animals' lifespan extended by 30 percent.

The study is published in The Journal of Clinical Investigation.