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JOURNAL: Int J Cancer 2003;106:856-862.
AUTHORS: Dr. Johannes V. Swinnen
ABSTRACT: Epigallocatechin-3-gallate (EGCG), a component of green tea, seems to induce apoptosis of prostate cancer cells by inhibiting fatty acid synthase (FAS), an enzyme that is overexpressed in a variety of human malignancies.
COMMENTARY: Although numerous reports have indicated an anticancer effect for EGCG, the exact mechanisms involved were unclear.
Several synthetic compounds have been shown to inhibit FAS and induce cancer cell apoptosis. Recently, however, researchers showed that EGCG, a natural compound, could inhibit FAS in chicken liver extracts. Therefore, it is possible that EGCG's anticancer effects are due to its ability to block FAS.
To investigate, Dr. Johannes V. Swinnen and colleagues, from the Catholic University of Leuven, evaluated EGCG's effects in cultured prostate cancer cells and in normal fibroblasts.
EGCG caused dose-dependent inhibition of FAS in the cancer cells that coincided with a decrease in cell growth and induction of apoptosis. In contrast, epicatechin, a chemical similar to EGCG that does not block FAS, did not inhibit cancer cell growth or induce apoptosis.
EGCG slowed the growth rate, but did not induce apoptosis of normal fibroblasts--cells with low levels of FAS activity. This provides further evidence that EGCG's anticancer effects are mediated by FAS inhibition, the researchers note.
"It may be concluded that EGCG-medicated FAS inhibition is undoubtedly one of the mechanisms that merit consideration when trying to explain the cancer chemopreventive and chemotherapeutic potential of this green tea polyphenol," the authors state.