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August 12, 2005

Green Tea Inhibits Invasive Behavior of Breast Cancer Cells.

Topics: Medicine

Green tea continues to be a topic of interest for researchers, and for good reason. Numerous epidemiological studies have suggested that consumption of green tea may decrease the risk of cancer, and the chemopreventive effect of green tea polyphenols (GTP) has been demonstrated through the inhibition of cell proliferation and angiogenesis in cell culture and animal models of breast cancer.

Metastasis of breast cancer is the major reason for the high mortality of breast cancer patients and is directly linked to the invasive behavior of breast cancer cells. Cancer metastasis consists of several interdependent processes including cancer cell adhesion, cancer cell migration, and invasion of cancer cells.

In a study reported in the journal "Nutrition and Cancer," researchers evaluated the effect of green tea polyphenols on human breast cancer cells, and showed that in addition to inhibiting cell growth, green tea polyphenols also suppressed the invasive behavior of MDA-MB-231 breast cancer cells (Human Caucasian breast adenocarcinoma cell line). They found that the anti-invasive effects of the green tea polyphenols were the result of the inhibition of constitutively active transcription factors AP-1(activator protein-1) and NF-kappaB, which further suppressed secretion of urokinase plasminogen activator (uPA) from breast cancer cells.

Based on their results, it appears tht the treatment of the cells with green tea polyphenols resulted in the inhibition of formation of signaling complexes responsible for cell adhesion and migration and cell invasion. The researcher's results indicate that green tea polyphenols may possibly contribute to the anticancer effects of green tea by inhibiting the invasive behavior of cancer cells.

But whether you're interested in the anti-cancer benefits of green tea(although the FDA recently suggested no cancer benefit - there is a plethora of solid basic research to indicate otherwise, including the work discussed in this post) or just interested in green tea because you like the taste, there are a many health benefits that accompany a regular habit of green tea. In fact, in addition to the anti-cancer benefit (studies have found an association between consuming green tea and a reduced risk for several cancers, including, skin, breast, lung, colon, esophageal, and bladder) there is research indicating that the antioxidants in green tea lower total cholesterol levels as well as improve the ratio of good (HDL) cholesterol to bad (LDL) cholesterol, help in diabetes, heart disease and stroke, plus help in age-related and brain degeneration diseases.

So why is green tea getting all the attention in the science world? Mainly because of the antioxidant epigalloctechin-3 gallate ( EGCG ) that is preserved in green tea, but lost in oolong and black varieties when fermented. Antioxidants are thought to prevent free radicals. Whenever a free radical reacts with a non-radical, a chain reaction is initiated until two free radicals react and then terminate the propagation with a 2-electron bond, with each radical contributing its single unpaired electron. The free radicals of special interest in aging are the oxygen free radicals (OH., H., O2.-). These free radicals often take an electron away from a "target" molecule to pair with their single free electron; this is what is commonly termed "oxidation." The term "reactive oxygen species" is used to refer to these oxidants and the oxygen free radicals.

In the human body, oxidized free radicals are believed to cause tissue damage at the cellular level, causing damage to our DNA, mitochondria (the powerhouse of the cell), and cell membrane, and have often been referred to as one of the causes attributed to aging, cancer, heart disease, and other human ailments. While the production of free radicals is a normal part of metabolism at the cellular level, things such as excessive alcohol intake, smoking, and various chemical exposures only serve to increase the amount of free radicals present in the body. To prevent free radical damage the body has a defense system of antioxidants, which are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged (as in Vitamin C), or seek out and scavenge free radicals (as in Vitamin E ).

Research has indicated that one of the main antioxidants found in green tea ( epigalloctechin 3-gallate a.k.a. EGCG ) has been found to be much more powerful than both Vitamins C and E. Compared to other known antioxidants, EGCG was found to be 100 times more effective than vitamin C, 25 times more effective than Vitamin E and twice as powerful as resveratrol at neutralizing free radicals.

My favorite tea is Sencha green tea, of which I drink 4 or 5 cups a day(I always use loose tea ordered from Japan (I know Kevin and I find his tea to be of excellent quality and reasonable price) or purchased at Teavana - lots from Japan at O-cha.com are much fresher and better tasting). In the morning, instead of Sencha, I'll have a couple of cups of
Gyokuro(has somewhat of a nutty flavor), from which Matcha is made. If you don't find Sencha to be especially flavorful, mix Rooibos tea and Sencha in equal proportions (one rounded tsp. each in 10 oz. water) for an especially healthy drink packed with a broad spectrum of antioxidants.

So, enjoy your green tea!

Related:
Potential therapeutic properties of green tea polyphenols in Parkinson's disease.

BBC News: Green tea 'can block cancer'

Modulation of N-methyl-N-nitrosourea induced mammary tumors in Sprague-Dawley rats by combination of lysine, proline, arginine, ascorbic acid and green tea extract.

Growth inhibitory and antimetastatic effect of green tea polyphenols on metastasis-specific mouse mammary carcinoma 4T1 cells in vitro and in vivo systems.

Tea Time for Good Health

Posted by Richard at August 12, 2005 11:10 AM



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