Tea polyphenols, their biological effects and potential molecular targets
Di Chen1, Vesna Milacic1, Marina Si Chen1, Sheng Biao Wan2, Wai Har Lam2, Congde Huo2, Kristin R. Landis-Piwowar1, Qiuzhi Cindy Cui1, Anil Wali1,3, Tak Hang Chan2 and Q. Ping Dou1
1The Prevention Program, Barbara Ann Karmanos Cancer Institute and Department of Pathology, School of Medicine, Wayne State University, Detroit, Michigan, USA, 2Department of Applied Biology and Chemical Technology and the Open Laboratory for Chiral Technology and Central Laboratory, Institute of Molecular Technology for Drug Discovery and Synthesis, the Hong Kong Polytechnic University, Hong Kong SAR, P.R. China and 3John A. Dingell Veterans Hospital, Detroit, Michigan, USA.
Offprint requests to: Q. Ping Dou, The Prevention Program, Barbara Ann Karmanos Cancer Insittute and Department of Pahtology, School of Medicine, Wayne State University, 640-1 HWCRC, 4100 John R Rd, Detroit, Michigan, 48201 USA. e-mail: firstname.lastname@example.org
Summary. Tea is the most popular beverage in the world, second only to water. Tea contains an infusion of the leaves from the Camellia sinensis plant rich in polyphenolic compounds known as catechins, the most abundant of which is (-)-EGCG. Although tea has been consumed for centuries, it has only recently been studied extensively as a health-promoting beverage that may act to prevent a number of chronic diseases and cancers. The results of several investigations indicate that green tea consumption may be of modest benefit in reducing the plasma concentration of cholesterol and preventing atherosclerosis. Additionally, the cancer-preventive effects of green tea are widely supported by results from epidemiological, cell culture, animal and clinical studies. In vitro cell culture studies show that tea polyphenols potently induce apoptotic cell death and cell cycle arrest in tumor cells but not in their normal cell counterparts. Green tea polyphenols were shown to affect several biological pathways, including growth factor-mediated pathway, the mitogen-activated protein (MAP) kinase-dependent pathway, and ubiquitin/proteasome degradation pathways. Various animal studies have revealed that treatment with green tea inhibits tumor incidence and multiplicity in different organ sites such as skin, lung, liver, stomach, mammary gland and colon. Recently, phase I and II clinical trials have been conducted to explore the anticancer effects of green tea in humans. A major challenge of cancer prevention is to integrate new molecular findings into clinical practice. Therefore, identification of more molecular targets and biomarkers for tea polyphenols is essential for improving the design of green tea trials and will greatly assist in a better understanding of the mechanisms underlying its anti-cancer activity. Histol Histopathol 23, 487-496 (2008)
Key words: Tea polyphenols, Molecular targets, Cancer prevention, Cancer treatment