Green tea: role in cancer prevention

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>> Monday, September 14, 2009

보성 녹차밭

A cup of tea early morning is quite refreshing. Almost all country in the world has trend of drinking tea. Generally it is divided into three basic categories; non-fermented, semi-fermented and fermented. Among these types, non-fermented tea i. e green tea has many healthy benefits. Fuzuki et al. has reported that green tea helps in cancer prevention (Cancer lett. 2002, 188, 9). It has been revealed that green tea showed its anti-cancer activity through inhibiton of mitogen-activated protein kinases (MAPK), growth factor-related cell signaling, activation of activator protein 1 ( AP-1) and nuclear factor-B (NF-kappa B), topoisomerase I, matrix metalloproteinases and other potential targets.
Green tea is made with leaves of Camellia sinensis. It originates from China and spread throughout the other asian countries like Japan, Korea and recently to many western countries. Green tea is composed of polyphenols especially catechins, among which the most abundant is epigallocatechin-3-galate (EGCG). EGCG is the most effective chemopreventive agent.

In this paper, the role of EGCG in cancer prevention has been summarized;
Role of EGCG in cancer initiation stage
Oncogene mutation and reactive oxygen species (ROS) plays an important role in cancer initiation. When oncogene mutation occurs, the procacinogen become activated via the activation of phase I enzymes such as the cytochrome P450s. ROS actively participate in the metabolic activation of procarcinogens. EGCC can neutralize these procarcinogens by inhibiting the activity of cytochrome P450 enzymes and modulating ROS. It has been demonstrated that EGCG is a powerful antioxidant.
Role of EGCG in cancer promotion stage
EGCG possess its anticancer effect by interfering with many signaling pathways and modulating cell cycle.
Role of EGCG in cancer progression stage
During progression of cancer, apoptosis and enzymes like urokinase and metalloproteinase (MMPs) plays an important role. EGCG can inhibit the proliferation of cancer cells by inducing apoptosis and inhibiting the function of these enzymes. Recently Kuzuhara et. al. (J. Biol. Chem. 2006, 282, 17446) proposed that DNA and RNA served as new binding targets of EGCG.
Because of its diverse role, EGCG can be developed as multi-targeted anticancer agents and can act as a promising template for the design of various anticancer derivatives.
(Source: Molecules 2007, 12, 946-957 )


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