Inhibition of intestinal tumorigenesis in Apc^Min/+ mice by green tea polyphenols (Polyphenon E) and individual catechins

In this work, we compared the cancer preventive activities of Polyphenon E (PPE), a standardized green tea polyphenol preparation given in diet versus drinking fluid as well as the activities of PPE versus individual catechins. We treated Apc^Min/+ mice for 9 wk with 0.08% (-)-epigallocatechin-3- gallate (EGCG), 0.08% (-)-epicatechin-3-gallate, or 0.12% PPE in drinking fluid or diet. Only 0.12% dietary PPE and 0.08% EGCG in drinking fluid significantly decreased tumor multiplicity (70% and 51%, respectively). Compared to PPE in drinking fluid, dietary PPE delivered twofold more EGCG to the small intestine. Immunohistochemistry showed that adenomas in groups treated with PPE and EGCG had decreased cell proliferation, β-catenin nuclear expression, and phospho-Akt levels; higher cleaved caspase-3 levels, and partially restored retinoid X receptor a expression. The results suggest that these molecular events contribute to the cancer prevention activity of EGCG and PPE. Furthermore, diet appears to be a better route of administration for PPE than drinking fluid.