Sunday, December 24, 2006

Green Tea Targets Cancer

New Research Finds More Effective Than Cancer Drugs Against Cancer-Sparking Protein Found Throughout the Body

WASHINGTON, DC – Speaking at an international conference on diet and cancer, researchers funded by the American Institute for Cancer Research (AICR) presented evidence that a major component in green tea may short-circuit the cancer process in a striking new way that scientists had not foreseen.

“We have determined that a unique quirk of biochemistry allows green tea’s protective effects to extend to many different kinds of cells,” said Dr. Thomas A. Gasiewicz, a Professor of Environmental Medicine at the University of Rochester Medical Center. “In fact, the active green tea substance – called EGCG – seems to target one protein that is particularly common throughout our bodies, and it does so with a degree of precision that cancer drugs still aren’t able to match.”

The protein in question is called HSP90, which is present at higher levels in many cancer cells. Scientists believe that in some circumstances, HSP90 helps to trigger the cascade of events that eventually leads to cancer.

When EGCG binds to this protein, however, it helps prevent these events from happening. This is important, because HSP90 is found throughout our bodies, in many different cells and tissues.
“If further research confirms that EGCG’s ability to bind to such a basic and pervasive protein enables it to extend its protective effect throughout our bodies, it explains a scientific mystery,” said Gasiewicz. “Studies that track the diets of human subjects over several years – particularly studies conducted in Asia, where green tea consumption is common – have associated regular usage of green tea with lower risk for cancers that are vastly different from one another.”

EGCG Does What Cancer Drugs Can’t Do…Yet

The protein called HSP90 is essentially a “helper” or “chaperone” protein, in that it exists to
help stabilize other proteins and keep them together. Because it has to bind to so many different proteins it is present, in varying amounts, in all of our cells. In fact, it is referred to as a “promiscuous protein” because it is so pervasive.

But scientists have recently discovered that cancer cells tend to have higher levels of HSP90 than healthy cells. This has led scientists to try to develop pharmaceutical means to block HSP90, to keep it from sending the specific biochemical signals that can trigger cancer. So far, they have been unable to perfect a drug that is both highly specific and easy to administer.
What the AICR researchers have discovered is that the active substance in green tea already does what drugs still can’t do: “EGCG targets HSP90, binds directly to it, and keeps it from passing on signals that can start the cancer process,” said Gasiewicz. “As a result, potentially harmful genes are less likely to get turned on, and the cascade of events leading to cancer is cut off before it begins.”

The fact that EGCG binds directly to a protein that is found everywhere in the body suggests that it may be able to provide effective and simultaneous cancer protection in vastly different tissues and organs, Gasiewicz said.

Tea May Cut Ovarian Cancer Risk

Freshly brewed teas contain more natural antioxidants than processed teas.

New research suggests drinking tea may help lower the risk of ovarian cancer. Swedish researchers have found evidence that drinking a couple of cups of tea every day might help reduce the risk of developing ovarian cancer.

The study involved 61,057 Swedish women who answered a questionnaire about their diets and then were tracked for an average of 15 years through 2004.

During that time, 301 women developed ovarian cancer. Those who reported drinking two or more cups of tea a day were 46 percent less likely to develop the disease than women who drank no tea. Drinking less than two cups also appeared to help, but not as much.
The researchers did not break out the results by tea types, but most of the tea drinkers consumed black tea. Both black and green tea contain polyphenols - substances thought to block cell damage that can lead to cancer.

Previous studies on whether tea might help prevent various kinds of cancer have yielded conflicting results. Researchers Susanna Larsson and Alicja Wolk of the Karolinska Institute in Stockholm said more research is needed to sort out the inconsistencies.

Their study was published in Monday's Archives of Internal Medicine. "If these findings are real, they'd be important because ovarian cancer is the fourth leading cause of cancer death in women," said Marji McCullough, a nutritional epidemiologist at the American Cancer Society.
Ovarian cancer is diagnosed in more than 20,000 U.S. women yearly. On average, U.S. women face about a 1-in-58 chance of developing the disease. It is hard to detect early because its symptoms, including abdominal bloating, indigestion and urinary urgency, can be vague and mimic less serious conditions.What's not clear from this study is which type of tea is best. Sixty-eight percent of the women who took part reported drinking mainly black tea at least once a month. Previous research has suggested that green, black, and other teas all contain the antioxidants thought to be beneficial.