Painkillers for Colon Cancer, Too

Painkillers aren't just for pain anymore as research has shown new uses for them in the fight against heart disease, stroke and Parkinson's disease. In one of the latest findings, researchers have discovered how certain non-steroidal anti-inflammatory drugs, or NSAIDs (pronounced EN seds), Celebrex®, COX-2 inhibitors, can actually reduce the risk of colon cancer and perhaps treat it.

Scientists have long known that colon cancer tissues contain high levels of the enzyme cyclooxygenase-2 (COX-2), the same enzyme causing inflammatory reactions and pain in our bodies. They have now tested some of the COX-2 blocking compounds for their ability to kill or inhibit the growth of colon cancer.

At the University of California, Irvine, Dr. Andrezej Tarnawski and his group looked into human colon cancer cells and discovered that a substance called prostaglandin E2, or PGE2, which is produced by the COX-2 enzyme, stimulates the growth and reproduction of cells, particularly cancer cells.

Paving the way for new cancer drugs

"Understanding how prostaglandins cause cancer growth and how their effects can be blocked will pave the way for development of new anticancer medicines," says Tarnawski, chief of the UCI College of Medicine division of gastroenterology and of the Veterans Administration Medical Center.

The COX-2 enzyme is produced in cancer cells by a specific gene. Certain drugs may suppress the enzyme directly, such as COX-2 inhibitors and Celebrex, which are popular arthritis pain relievers. Or, perhaps drugs will be developed to prevent or block activation of the gene. Tarnawski's work appeared in the journal Nature-Medicine.

Black tea also may hold the key

Joining Tarnawski in the quest for anti-cancer drugs based on the COX-2 model is Kuang Yu Chen of Rutgers University in New Brunswick, N.J. Chen has been studying the group of compounds called polyphenols found in black tea. Black tea is another substance that has shown in numerous studies to have a protective effect against some human cancers.

With the research by Tarnawski in place, Chen finds black tea's "secret weapon" may be the polyphenol known as theaflavin-3'-monogallate, or TF-2. As it turns out, there is a TF-2 and COX-2 gene connection.

"(Black tea) shows very interesting properties" against colon cancer cells by leaving normal cells unharmed, while cancer cells "commit suicide" in droves," Chen says. By adding tea-derived TF-2 to both healthy cells and colorectal cancer cells in laboratory experiments, Chen's group found that while normal cells grew in the presence of TF-2, cancer cells died.

Using this information, the Rutgers team found that TF-2 acts to suppress the activity of the COX-2 gene. The COX-2 gene has been the focus of intense research because the gene helps trigger the inflammation process by producing the COX-2 enzyme. This discovery is an important step in events that can change normal cells into cancer cells. Furthermore, according to Chen, the relationship between COX-2 and colon cancer has been "very well established."

Pharmaceutical companies are using this new information to develop agents that will either inhibit the COX-2 gene or the COX-2 enzyme itself. Chen believes the secret may actually lie in black tea. Though polyphenols exist in many other foods, such as green tea and grape skins, their effect against cancer cells are "less dramatic," Chen says.

The same grape skin polyphenol, known as resveratrol, has been shown to be the helpful ingredient responsible for the cardiovascular benefits found in red wine and, to a lesser extent, in grape juice. Chen's group has modified the grape skin polyphenols in the lab and greatly enhanced their cancer-killing effect.

"By rationally modifying the chemical structure of nutraceuticals (such as grape skin polyphenols), we can actually improve on nature," Chen says.

While research shows a link between taking NSAIDs and COX-2 inhibitors and a lower cancer risk, doctors at this time are not recommending people take the painkillers to prevent cancer. More research is needed.

However, you might try black tea. Purdue University researchers say that the equivalent of drinking more than four cups a day can slow or prevent the growth of cancer cells in the laboratory. The researchers tested the effects of both green tea and black tea on cancer cells, but the effects in the human body have yet to be determined.

Sources:

Dollinger M, Rosenbaum, EH, Tempero M., et al. Everyone's Guide to Cancer Therapy, Fourth Edition, Kansas City, Missouri: Andrews McMeel Publishing, 2002.

This article was reviewed and updated June 2007.