Background: Green tea polyphenols (GTPs) have been shown to play a role in the regulation of cell proliferation, apoptosis and inflammation in prostate cancer cells in vitro and in animal models using human prostate cancer cell xenografts. While there is extensive epidemiological and basic scientific evidence for these effects of GTPs, data from human intervention studies is much more limited. Objective: We conducted a phase II intervention study to evaluate the anticarcinogenic effects of green tea in prostate cancer by administering green tea in men prior to prostatectomy. Design: 79 men, diagnosed with prostate cancer and scheduled for prostatectomy, were randomized to either 6 cups of brewed green tea or water daily for 3-8 weeks prior to surgery. 67 men (GT group, N=34; control group, N=33) completed the intervention. Blood and urine samples were collected before and after the intervention and sections of prostate tissue were frozen as OCT blocks following the pathology evaluation. Serum prostate specific antigen (PSA) concentration was determined by ELISA assay and prostate tissue PSA protein concentration was measured by Western blot. The prostate concentration of GTPs and their metabolites was measured using high-performance liquid chromatography (HPLC) with CoulArray electrochemical detection. The protein expression of Ki67 (proliferation), Bcl2, Bax (apoptosis) and nuclear factor kappa B (NFκB) (inflammation) were determined by immunostaining in prostate tissue of confirmed tumor areas.

Results: Statistical analysis within each treatment arm showed that the serum PSA concentration was significantly decreased in the GT group (final vs. baseline blood) (P<0.01), while no change was observed in the control group. Prostate tissue PSA protein expression was lower in men consuming GT compared to water control (p=0.06). Bioactive GTPs including epigallocatechin gallate (EGCG) and its methyl metabolite 4″-O-methyl EGCG and epicatechin gallate (ECG) were detected in prostate tissue from 31 of 34 men consuming GT but were absent in prostates in the control group. Intranuclear NFκB staining was decreased significantly while there was no change in cytoplasmic NFκB staining in prostate tumors from men drinking GT by comparison to tumors from the control group. The ratio of cytoplasmic staining of pro-apoptotic Bax to Bcl-2 was increased significantly while cytoplasmic Bcl2 and Bax staining were not changed. Nuclear Ki67 staining was not changed with GT consumption.

Conclusion: Green tea consumption may contribute to the inhibition of prostate tumor growth through reducing inflammation and stimulating apoptosis. Analyses of additional markers are needed to confirm these findings.

Citation Format: Susanne M. Henning, Piwen Wang, William J. Aronson, Catherine L. Carpenter, David Heber. Inhibition of NFκB and proapoptotic effect of green tea in prostate tumor tissue: A phase II clinical trial in men with prostate cancer. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B67.