Effect of Genistein on the Bioavailability and Intestinal Cancer Chemo: Preventive Activity of (-)-Epigallocatechin-3-Gallate
The green tea (Camellia sinensis) catechin, (-)-epigallocatechin-3-gallate (EGCG), has shown cancer-preventive activity in animal models. Previously, we have reported the bioavailability of EGCG in rats and mice. Here, we report that cotreatment of HT-29 human colon cancer cells with genistein (from soy) increased cytosolic EGCG by 2- to 5-fold compared with treatment with EGCG only. Inclusion of genistein, at non-cytotoxic concentrations, increased the growth inhibitory effects of EGCG against HT-29 cells (up to 2-fold at 20 μM genistein). Intragastric coadministration of EGCG (75 mg/kg) and genistein (200 mg/kg) to CF-1 mice resulted in an increase in plasma half-life (t1/2 148.7 ± 16.4 versus 111.5 ± 23.4 min) and exposure (AUC0→∞ 183.9 ± 20.2 versus 125.8 ± 26.4 μg/ml × min) of EGCG. Cotreatment with genistein also increased the maximal concentration (Cmax), 6 h exposure (AUC0→360min), and t1/2 of EGCG in the small intestine by 2.0-, 4.7- and 1.4-fold, respectively, compared with mice treated with EGCG only. Contrary to our expectations, the combination of 0.01% EGCG in the drinking fluid and 0.2% genistein in the diet enhanced intestinal tumorigenesis in male adenomatous polyposis coli (APC)min/+ mice. This combination increased the multiplicity of tumors in the medial and distal small intestine: the largest increase was in tumors >2 mm in diameter (4.3-fold compared with controls). This study demonstrates that although genistein can enhance EGCG bioavailability and in vitro growth inhibitory activity, this combination enhances tumorigenesis in the APCmin/+ mouse. These results further show the need for careful cancer prevention studies in animal models and for caution when interpreting data from in vitro studies.
MSU Digital Commons Citation
Lambert, Joshua D.; Kwon, Seok Joo; Ju, Jihyeung; Bose, Mousumi; Lee, Mao Jung; Hong, Jungil; Hao, Xingpei; and Yang, Chung S., "Effect of Genistein on the Bioavailability and Intestinal Cancer Chemo: Preventive Activity of (-)-Epigallocatechin-3-Gallate" (2008). Department of Nutrition and Food Studies Scholarship and Creative Works. 45.