Green Tea Extracts for the Prevention of Metachronous Colorectal Adenomas: A Pilot Study

Shimizu, Masahito; Fukutomi, Yasushi; Ninomiya, Mitsuo; Nagura, Kazuo; Kato, Tomohiro; Araki, Hiroshi; Suganuma, Masami; Fujiki, Hiroyuki; Moriwaki, Hisataka

doi:10.1158/1055-9965.epi-08-0528

Cited by 185 publications

(140 citation statements)

References 41 publications

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“…Does green tea can decrease the CRC risk? Results from a human experimental randomized controlled trail support the hypothesis of a protective role of green tea for the chemoprevention of metachronous colorectal adenomas (Shimizu et al, 2008). Another randomized, placebo controlled, multicentre trial to investigate the effect of green tea extract nutriprevention of metachronous colon adenomas in the elderly population is undergoing (Stingl et al, 2011), whether it can obtain a significant result is still unkown.…”

Section: Discussionmentioning

confidence: 91%

Association Between Green Tea and Colorectal Cancer Risk: A Meta-analysis of 13 Case-control Studies

Wang

Zeng²,

Duan³

et al. 2012

Asian Pacific Journal of Cancer Prevention

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Objective: Experimental studies have suggested green tea to be a chemopreventive agent for colorectal cancer, and many studies have examined possible associations. However, the conclusions were inconsistent or even contradictory, so we performed a meta-analysis based on published case-control studies to explore if green tea is indeed a protective factor. Methods: PubMed was searched up to May 10 th , 2012 for relevant studies, and references of included studies were manually searched. Finally 13 eligible studies, involving 12,636 cases and 38,419 controls were identified. After data extraction, a meta-analysis was performed using CMA v2 software. Results: The results indicated there may be a weak but not statistically significant reduced risk of colorectal cancer with high dose of green tea intake (OR=0.95, 95% CI:0.81-1.11, p=0.490.69-0.98). This protective effect was also found in all subgroups, except in American and European populations. Sensitivity analysis indicated the result to be robust. Publication bias was not detected by either funnel plot or Egger tests. Conclusion: The results of this meta-analysis indicate a weak lower tendency for colorectal cancer development with green tea consumption, but available epidemiologic data are insufficient to conclude that green tea may protect against colorectal cancer in humans.

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Section: Discussionmentioning

confidence: 91%

Association Between Green Tea and Colorectal Cancer Risk: A Meta-analysis of 13 Case-control Studies

Wang

Zeng²,

Duan³

et al. 2012

Asian Pacific Journal of Cancer Prevention

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“…For instance, supplementation with GTCs can significantly prevent the development of both colorectal adenomas and prostate cancers without causing adverse effects (46,47). A double-blind, placebo-controlled pilot study showed that EGCG has the potential to increase fat oxidation in men (48), although more studies with a larger sample size are required to confirm this effect.…”

Section: Gapdhmentioning

confidence: 99%

Preventive Effects of (−)-Epigallocatechin Gallate on Diethylnitrosamine-Induced Liver Tumorigenesis in Obese and Diabetic C57BL/KsJ-db/db Mice

Shimizu

Sakai²,

Shirakami³

et al. 2011

Cancer Prevention Research

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Obesity and related metabolic abnormalities, including insulin resistance and a state of chronic inflammation, increase the risk of hepatocellular carcinoma. Abnormal activation of the insulin-like growth factor (IGF)/ IGF-1 receptor (IGF-1R) axis is also involved in obesity-related liver tumorigenesis. In the present study, we examined the effects of (À)-epigallocatechin gallate (EGCG), a major biologically active component of green tea, on the development of diethylnitrosamine (DEN)-induced liver tumorigenesis in C57BL/KsJ-db/db (db/db) obese mice. Male db/db mice were given tap water containing 40 ppm DEN for 2 weeks and then they received drinking water containing 0.1% EGCG for 34 weeks. At sacrifice, drinking water with EGCG significantly inhibited the development of liver cell adenomas in comparison with the control EGCG-untreated group. EGCG inhibited the phosphorylation of the IGF-1R, ERK (extracellular signal-regulated kinase), Akt, GSK-3b (glycogen synthase kinase-3b), Stat3, and JNK (c-Jun NH 2 -terminal kinase) proteins in the livers of experimental mice. The serum levels of insulin, IGF-1, IGF-2, free fatty acid, and TNF-a were all decreased by drinking EGCG, which also decreased the expression of TNF-a, interleukin (IL)-6, IL-1b, and IL-18 mRNAs in the livers. In addition, EGCG improved liver steatosis and activated the AMP-activated kinase protein in the liver. These findings suggest that EGCG prevents obesity-related liver tumorigenesis by inhibiting the IGF/IGF-1R axis, improving hyperinsulinemia, and attenuating chronic inflammation. EGCG, therefore, may be useful in the chemoprevention of liver tumorigenesis in obese individuals. Cancer Prev Res; 4(3); 396-403. Ó2011 AACR.

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“…Based on our successful prevention study on the recurrence of colorectal adenomas in Japanese patients as a result of daily consumption of green tea beverage supplemented with tablets of green tea extract containing (−)-epicatechin (EC; ref. 7), we think that the cancer-preventive activity of curcumin could be enhanced using some components of the diet in daily consumption. To achieve this, we first looked at the effects of EC, which is an inert tea catechin (8), without a galloyl group, in the above-mentioned cancer-preventive activities.…”

Section: Introductionmentioning

confidence: 99%

New Role of (−)-Epicatechin in Enhancing the Induction of Growth Inhibition and Apoptosis in Human Lung Cancer Cells by Curcumin

Saha

Kuzuhara

Echigo

et al. 2010

Cancer Prevention Research

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Curcumin, a phenolic compound isolated from the plant Curcuma longa (Linn), is ingested every day in the Indian subcontinent and is well reported to possess cancer-preventive activity. To achieve effective cancer prevention with curcumin, we need to find a new method to enhance the effects of curcumin in the diet. Based on our evidence that (−)-epicatechin (EC), an inert catechin, enhances the cancer-preventive activity of green tea catechins, we studied the enhancing effects of EC on inductions of growth inhibition and apoptosis in human lung cancer cell lines PC-9 and A549 with curcumin. The combination of curcumin with EC significantly increased the inhibition of cell growth compared with curcumin or EC alone. The combination similarly increased both apoptosis and expression of GADD153 and GADD45 genes, associated with their enhanced protein production. Knockdown of GADD153 or GADD45 by small interfering RNA abrogated the apoptosis induction and growth inhibition induced by the combination, indicating the crucial role of their upregulation. Treatments of PC-9 cells with c-Jun-NH 2 -kinase inhibitor SP600125, with p38 mitogen-activated protein kinase inhibitor SB202190 and with PD98059 (extracellular signalregulated kinase 1/2 inhibitor) all increased the upregulation of GADD153 and GADD45 genes by the combination. Because EC was previously shown to enhance the incorporation of EGCG into PC-9 cells, we think that EC has similar effects on curcumin. This report is the first report on the enhancing effects of EC on curcumin, and the data suggest that EC plays a significant role in the enhancement of the cancerpreventive activity of curcumin in the diet. Cancer Prev Res; 3(8); 953-62. ©2010 AACR.

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Green Tea Extracts for the Prevention of Metachronous Colorectal Adenomas: A Pilot Study

Cited by 185 publications

References 41 publications

Association Between Green Tea and Colorectal Cancer Risk: A Meta-analysis of 13 Case-control Studies

Association Between Green Tea and Colorectal Cancer Risk: A Meta-analysis of 13 Case-control Studies

Preventive Effects of (−)-Epigallocatechin Gallate on Diethylnitrosamine-Induced Liver Tumorigenesis in Obese and Diabetic C57BL/KsJ-db/db Mice

New Role of (−)-Epicatechin in Enhancing the Induction of Growth Inhibition and Apoptosis in Human Lung Cancer Cells by Curcumin

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