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Green Tea

Am J Obstet Gynecol. 2010 Mar;202(3):289.e1-9. Epub 2010 Jan 13.

Green tea extract inhibits proliferation of uterine leiomyoma cells in vitro and in nude mice.

Zhang D, Al-Hendy M, Richard-Davis G, Montgomery-Rice V, Sharan C, Rajaratnam V, Khurana A, Al-Hendy A.

Center for Women's Health Research, Department of Obstetrics and Gynecology, Meharry Medical College, Nashville, TN 37208, USA.

OBJECTIVE: The purpose of this study was to investigate the effect of epigallocatechin gallate (EGCG) on rat leiomyoma (ELT3) cells in vitro and in a nude mice model. STUDY DESIGN: ELT3 cells were treated with various concentrations of EGCG. Cell proliferation, proliferation cell nuclear antigen (PCNA), and cyclin-dependent kinase 4 (Cdk4) protein levels were evaluated. ELT3 cells were inoculated subcutaneously in female athymic nude mice. Animals were fed 1.25 mg EGCG (in drinking water)/mouse/day. Tumors were collected and evaluated at 4 and 8 weeks after the treatment. RESULTS: Inhibitory effect of EGCG (200 micromol/L) on ELT3 cells was observed after 24 hours of treatment (P < .05). At > or = 50 micromol/L, EGCG significantly decreased PCNA and Cdk4 protein levels (P < .05). In vivo, EGCG treatment dramatically reduced the volume and weight of tumors at 4 and 8 weeks after the treatment (P < .05). The PCNA and Cdk4 protein levels were significantly reduced in the EGCG-treated group (P < .05). CONCLUSION: EGCG effectively inhibits proliferation and induces apoptosis in rat ELT3 uterine leiomyoma cells in vitro and in vivo.

Source: PubMed



Cancer Epidemiol Biomarkers Prev. 2008 Nov;17(11):3020-5.

Green tea extracts for the prevention of metachronous colorectal adenomas: a pilot study.

Shimizu M, Fukutomi Y, Ninomiya M, Nagura K, Kato T, Araki H, Suganuma M, Fujiki H, Moriwaki H.

Department of Medicine, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan.

BACKGROUND: Experimental studies indicate the chemopreventive properties of green tea extract (GTE) on colorectal cancer. Epidemiologically, green tea consumption of > 10 cups daily reduced colorectal cancer risk in Japanese. Because colorectal adenomas are the precursors to most sporadic colorectal cancers, we conducted a randomized trial to determine the preventive effect of GTE supplements on metachronous colorectal adenomas by raising green tea consumption in the target population from an average of 6 cups (1.5 g GTE) daily to > or = 10 cups equivalent (2.5 g GTE) by supplemental GTE tablets. METHODS: We recruited 136 patients, removed their colorectal adenomas by endoscopic polypectomy, and 1 year later confirmed the clean colon (i.e., no polyp) at the second colonoscopy. The patients were then randomized into two groups while maintaining their lifestyle on green tea drinking: 71 patients supplemented with 1.5 g GTE per day for 12 months and 65 control patients without supplementation. Follow-up colonoscopy was conducted 12 months later in 125 patients (65 in the control group and 60 in the GTE group). RESULTS: The incidence of metachronous adenomas at the end-point colonoscopy was 31% (20 of 65) in the control group and 15% (9 of 60) in the GTE group (relative risk, 0.49; 95% confidence interval, 0.24-0.99; P < 0.05). The size of relapsed adenomas was also smaller in the GTE group than in the control group (P < 0.001). No serious adverse events occurred in the GTE group. CONCLUSION: GTE is an effective supplement for the chemoprevention of metachronous colorectal adenomas.

Source: PubMed



Inflammopharmacology. 2008 Oct;16(5):208-12.

Green tea polyphenols as a natural tumour cell proteasome inhibitor.

Dou QP, Landis-Piwowar KR, Chen D, Huo C, Wan SB, Chan TH.

The Prevention Program, Barbara Ann Karmanos Cancer Institute and Department of Pathology, School of Medicine, Wayne State University, 540.1 HWCRC, 4100 John R Rd, Detroit, Michigan 48201, USA. [email protected]

The cancer-preventive effects of green tea and its main constituent (-)-epigallocatechin gallate [(-)-EGCG] are widely supported by results from epidemiological, cell culture, animal and clinical studies although the molecular target has not been well defined. We previously reported that ester bond-containing tea polyphenols, e. g. (-)-EGCG, and their synthetic analogs potently and specifically inhibited the proteasomal activity. Subsequently, we further demonstrated that methylation on green tea polyphenols under physiological conditions decreased their proteasome-inhibitory activity, contributing to decreased cancer-preventive effects of tea consumption. Since (-)-EGCG is unstable under physiological conditions, we also developed the peracetate-protected or prodrug form of (-)-EGCG, Pro-EGCG (1), and shown that Pro-EGCG (1) increases the bioavailability, stability, and proteasome-inhibitory and anticancer activities of (-)-EGCG in human breast cancer cells and xenografts, suggesting its [green tea] potential use for cancer prevention and treatment.

Source: PubMed