Yang Chung S, Lambert Joshua D, Hou Zhe, Ju Jihyeung, Lu Gang, Hao Xinpei
Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
Mol Carcinog. 2006 Jun;45(6):431-5. doi: 10.1002/mc.20228.
Inhibition of carcinogenesis by tea and tea polyphenols has been demonstrated in many animal models. The mechanisms of action have been extensively investigated mostly in cell culture systems with (-)-epigallocatechin-3-gallate (EGCG), the most active and major polyphenolic compound from green tea. However, the mechanisms of cancer preventive activity by tea and tea polyphenols are not clearly understood. This article discusses some of the reported mechanisms and possible targets for the action of EGCG. The difficulties and major issues in extrapolating data from studies in cancer cell lines to cancer prevention mechanisms are discussed. Activities observed in cell culture with high concentrations of EGCG may not be relevant because of the limited systemic bioavailability of EGCG. In addition, possible artifacts due to the auto-oxidation of EGCG may complicate this issue. Some recent studies revealed high-affinity EGCG binding proteins as possible direct targets for the action of EGCG. Validating the related cancer preventive mechanisms found in in vitro studies in animal models and human samples would be exciting.
茶和茶多酚对癌症发生的抑制作用已在许多动物模型中得到证实。其作用机制大多在细胞培养系统中进行了广泛研究，主要研究对象是（-）-表没食子儿茶素-3-没食子酸酯（EGCG），它是绿茶中活性最强且含量最多的多酚类化合物。然而，茶和茶多酚预防癌症的作用机制尚未完全明确。本文讨论了一些已报道的机制以及EGCG作用的可能靶点。还讨论了将癌细胞系研究数据外推至癌症预防机制时存在的困难和主要问题。由于EGCG的全身生物利用度有限，在细胞培养中观察到的高浓度EGCG的活性可能并不相关。此外，EGCG自氧化可能产生的假象也会使这个问题变得复杂。一些近期研究揭示了高亲和力的EGCG结合蛋白，它们可能是EGCG作用的直接靶点。在动物模型和人类样本中验证体外研究中发现的相关癌症预防机制将会令人兴奋。
