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Dec. 11, 1998 |
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Researchers identify anti-cancer compound in green tea SEATTLE -- (Cancer Digest -- 11-Dec. 1998) -- Researchers have shown that a chemical compound in green tea kills cancer cells and may explain the protective effect long associated with the drink. Purdue University researchers found that EGCg, a compound in green tea, inhibits an enzyme required for cancer cell growth and can kill cancer cells in the laboratory without harming healthy cells. The findings by Dorothy Morre and D. James Morre (pronounced MORE-aye) offer the first scientific evidence to explain precisely how this compound works within a cell to halt growth. The husband and wife research team presented their finding Monday (12/14/98) at the 38th annual meeting of the American Society for Cell Biology in San Francisco. Population researchers consistently find that people who drink more than four cups of green tea a day seem to have a lower overall risk of cancer, but scientists could not say how the tea produced these effects. The Purdue researchers tested a number of compounds found in tea, including epigallocatechin gallate, or EGCg, a primary component of green tea that has been linked to anti-cancer effects. Their studies, done with cells grown in the laboratory showed that low doses of EGCg were capable of inhibiting the production of a cell surface enzyme called, quinol oxidase or NOX, required for growth in both normal and cancerous cells. The doses tested were equivalent to what is contained in four cups of tea and did not inhibit the NOX activity of healthy cells. "Normal cells express the NOX enzyme only when they are dividing in response to growth hormone signals," Dorothy Morre says. "In contrast, cancer cells have somehow gained the ability to activate NOX at all times." The Morres also determined how the cancer cells died. "In the presence of EGCg, the cancer cells literally failed to grow or enlarge after division," Dorothy Morre says. "Then, presumably because they did not reach the minimum size needed to divide, they underwent programmed cell death, or apoptosis." The Morres found that EGCg inhibits the growth of, and kills, cancerous human mammary cells in laboratory conditions, but did not kill non-cancerous ones. Source: Purdue University: Purdue News Service: (765) 494-2096; e-mail, purduenews@uns.purdue.edu |
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