Green Tea Anti-Cancer Pathways

By Wendy Wells, NMD.

Epigallocatechin gallate (EGCG), a substance found in green tea is used in anti-cancer treatments. PI3K and rapamycin signaling pathways are active in a wide range of human cancers. EGCG's mechanistic effects on tumor growth was confirmed in the March 2011 edition of the Biochemical and Biophysical Research Communications journal, by GSK pharmaceutical researchers, in Collegeville, Pennsylvania. Their molecular docking tests demonstrated how EGCG attaches to, and competes for, PI3K kinase, and rapamycin (mToR). The researchers concluded how the evidence of this study points to,

"Another important molecular mechanism for the anticancer activities of EGCG." PMID:21300025

Cold Brew Extraction of Green Tea Yields Higher Growth Hormone

Researchers at the National Institute of Vegetable and Tea Science, in Shizoka Japan, tested epigallocatechin (EGCG) ratios by brewing green tea at different temperatures. Higher ratios of, the anti cancer agent, EGCGs where associated with a lower extraction temperature of 39° Fahrenheit, 4° Celcius (1:3). Lower extraction ratios where associated with a higher extraction temperature of 212° Fahrenheit, 100° Celcius (1:1). Next the low temperature, stronger extract ratio of EGCG was exposed to murine Peyer's patch cells, resulting in higher growth hormone (IgA) production. Conversely, the high temperature, low strength extraction of green tea EGCG polyphenols resulted in lower growth hormone production. The study's results where published in the December 2010 journal of Bioscience, Biotechnology and Biochemistry. PMID:21150115

Bioavailability and Antioxidant Activity of Tea Flavanols in Green Tea, Black Tea, or a Green Tea Extract Supplement

Green and black tea polyphenols have been extensively studied as anti-cancer, or chemo preventive agents. Many experiments have demonstrated their strong antioxidant activity. In the American Journal of Clinical Nutrition, December 2004 edition, the Center for Human Nutrition, David Geffen School of Medicine, University of California, Los Angeles, compared tea polyphenols and their effect on the antioxidant capacity. Thirty healthy subjects were randomly assigned to 3 different sequences of green tea, black tea, or a green tea extract supplement with a one week "washout" period in between treatments. Blood plasma was tested 8 hours after consumption of either green tea, black tea, or a green tea extract supplement. Results suggest that green tea extract supplements retain the beneficial effects of EGCG and may be used in future chemo prevention studies to provide a large dose of tea polyphenols without the side effects of caffeine associated with green and black tea drinks. PMID:15585768

Moderate Green Tea Consumption Effects Anti Oxidative and Plasma Lipid Profiles In Humans

In the Journal of Nutrition and Biochemistry, March 2005, researchers from the Department of Food Science and Microbiology, University of Milan, Italy recognized how the results obtained from dietary intervention studies where controversial. To test these conflicting findings they presented a study, investigating the effects of adding of two cups of green tea (approximately 250 mg of catechins) to the diet of a group of healthy volunteers. Another group followed the same controlled diet, without the added green tea.

Antioxidant status and lipid profile markers were measured at the beginning and the end of each trial. After 42 days, the consumption of green tea caused a significant increase in antioxidant activity, and a significant decrease in plasma peroxide levels that induce oxidative damage to lymph cell DNA. Also noted was a moderate, yet significant, decrease in LDL cholesterol (from 119.9 to 106.6 mg/dL) compared to the control group. The present study suggests "Green tea, consumed within a balanced controlled diet, improves anti oxidative plasma status and protects against oxidative damage in humans. PMID:15741048

Green tea polyphenols Protect Cultured Lung Cells From DNA Strand Breakage

Published in the Free Radical Biological Medicine journal, researchers mapped the influence of green tea polyphenols on the formation of DNA strand breaks and lipid per-oxidation products using cultured human lung cells. Cells were pretreated with green tea polyphenols for two hours and then exposed to cigarette smoke for 30 minutes. The cells were the analyzed after exposure. Green tea polyphenols inhibited cigarette smoke from inducing DNA breakage. DNA breakage increased significantly in cells not subjected to Green tea polyphenol protection. Pretreatment with green tea polyphenols also reduced the overall toxicity of H2O2 as determined by cell growth after exposure. Researchers conclude that green tea polyphenols inhibit DNA breakage, thereby contributing to the anti-cancer properties of green tea. PMID:9199885

Anti Cancer Effect of Green Tea Against Cigarette Smoke-Induced Mutations In Humans

In the Journal of Cell Biochemistry researchers commented how green tea (Camellia sinensis) is consumed daily between, during, and after meals in most Asian countries. Green tea and its major polyphenolics have demonstrated the prevention of chemically induced cancer tumors in a wide range of animal studies. Green tea polyphenols have demonstrated anti-mutagenic, anti-carcinogenic and antioxidant effects. Enzyme activities of glutathione peroxidase, catalase, and quinone reductase, and glutathione S-transferase are also induced.

The chemo-preventive effects of green tea and coffee among cigarette smokers were tested in 52 healthy males between the ages of 20-51. Daily intake of green tea and coffee totaled three cups per day, for six months. The frequencies of sister-chromatid exchange (SCE) in lymphocytes from each group were measured and analyzed. SCE rates were significantly elevated in smokers versus, non-smokers. Moreover, the frequency of SCE in smokers who consumed green tea was comparable to that of non-smokers, implying that green tea can block the cigarette induced increase in SCE frequency. Coffee, by contrast, did not exhibit a significant inhibitory effect. PMID:9591195

Green tea (EGCG) was also shown to inhibit Candida yeast infections. PMID:16585130

Green tea and cancer

Journal of Cancer Research. March, 2005 - A naturally occurring gallated polyphenols isolated from green tea leaves, (-)-epigallocatechin gallate (EGCG), has been shown to inhibit dihydrofolate reductase (DHFR) activity at concentrations found in the serum and tissues of green tea drinkers. This data provides the first evidence that the protective effect of drinking green tea on certain forms of cancer, as suggested by epidemiological studies, is due to the inhibition of DHFR by EGCG. This could also explain why tea extracts have been traditionally used in "alternative medicine" as anti-cancer and antibiotic agents, as well as in the treatment of psoriasis. PMID:15781612

Other molecular pathways altered by green tea extract.

  1. Epigallocatechin-3-gallate (EGCG) modulates the mitogen-activated protein kinase (MAPK) pathway bringing about growth inhibition.
  2. EGCG inhibits the insulin growth factor (IGF)-stimulated phosphorylation of its receptor.
  3. Cell cycle arrest by EGCG
  4. Promotion of apoptosis (cell death) by inhibition of bcl2 and bcl-xl 24678188

GTE along with vitamin C, proline and lysine reduces risk of metastasis and reoccurrence of breast cancer. PMID:24728148

EGCG shown to enhance the efficacy of chemotherapy in lung cancer patients. PMID:24712372

EGCG shown to have anti-inflammatory, anti-cancer, anti-steatotic (reduces fatty liver) effects on the liver. PMID:24489859

Drinking Your Cancer Prevention

A cup of green tea can contain anywhere from 50 to 400 mg of polyphenols. To have a chemoprotective effect, 500mg 3-4 times per day is needed which could equate to 10 cups or more. Pietta PG, Simonetti P, Gardana C, etal. Catechin metabolites after intake of green tea infusions. Biofactors 1998:8:111-118.




Wendy Wells

Author Wendy Wells is a licensed naturopathic physician in the state of Arizona.
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Related:

Camellia-sinensis leaves

Prostate Cancer Development and Green Tea
by the American Association for Cancer Research.