Greenteahaus:  The Green Tea Reference Library

Green tea or its components may enhance anticancer effects of drugs and prolong cancer patient survival

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1 Green tea consumption enhances survival of epithelial ovarian cancer patients. Asia Pac J Clin Nutr. 2004;13(Suppl):S116.
2 Low antioxidant vitamin intakes are associated with increases in adverse effects of chemotherapy in children with acute lymphoblastic leukemia. Am J Clin Nutr. 2004 Jun;79(6):1029-36.
3 Combination of theanine with doxorubicin inhibits hepatic metastasis of M5076 ovarian sarcoma. Clin Cancer Res. 1999 Feb;5(2):413-6.
4 Theanine and glutamate transporter inhibitors enhance the antitumor efficacy of chemotherapeutic agents. Biochim Biophys Acta. 2003 Dec 5;1653(2):47-59.
5 Epigallocatechin-3-gallate inhibits activation of HER-2/neu and downstream signaling pathways in human head and neck and breast carcinoma cells. Clin Cancer Res. 2003 Aug 15;9(9):3486-91.
6 Effects of epigallocatechin-3-gallate on growth, epidermal growth factor receptor signaling pathways, gene expression, and chemosensitivity in human head and neck squamous cell carcinoma cell lines. Clin Cancer Res. 2001 Dec;7(12):4220-9.
7 Epigallocatechin-3-gallate decreases VEGF production in head and neck and breast carcinoma cells by inhibiting EGFR-related pathways of signal transduction. J Exp Ther Oncol. 2002 Nov-Dec;2(6):350-9.
8 Enhancement of the activity of doxorubicin by inhibition of glutamate transporter. Toxicol Lett. 2001 Sep 15;123(2-3):159-67.
9 Efficacies of tea components on doxorubicin induced antitumor activity and reversal of multidrug resistance. Toxicol Lett. 2000 Apr 3;114(1-3):155-62.
10 Green tea polyphenols reversed multidrug resistance of cancer cells. J Pharm Pharmacol. 2004 Oct;56(10):1307-14.
11 Potential less toxic anticancer drugs to be used with green tea. Curr Med Chem Anti-Canc Agents. 2003 Nov;3(6):439-50.
12 Green tea may work like the antifolate cancer drug methotrexate.  The antifolate activity of tea catechins. Cancer Res. 2005 Mar 15;65(6):2059-64.

Abstracts
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1 Binns CW, Zhang M, Lee AH, Xie CX. Green tea consumption enhances survival of epithelial ovarian cancer patients. Asia Pac J Clin Nutr. 2004;13(Suppl):S116.

Aim: To investigate whether green tea consumption post-diagnosis can enhance survival of patients with epithelial ovarian cancer. Methods: A prospective cohort study was conducted in the community, Hangzhou, P. R. China. A cohort of 309 patients with histopathologically confirmed epithelial ovarian cancer, who were recruited in the study during 1999-2000, were followed for a minimum of three years. The variables measured included their survival time and the frequency and quantity of tea consumed post diagnosis. From the original cohort 294 (95.1%) subjects, or their close relatives, were traced and interviewed using a structured questionnaire in 2003. The actual number of deaths was obtained and the hazard ratios were calculated. Cox proportional models were used to compute adjusted hazard ratios (HR) and associated 95% confidence intervals (CI). These models were adjusted for age at diagnosis, locality, BMI, parity, stage at diagnosis, histo-pathologic grade of differentiation, cytology of ascites, and the presence of residual tumor after surgery. Results: Increasing frequency and quantity of tea consumption were associated a longer survival in Chinese women with epithelial ovarian cancer. The survival experiences were different between tea drinkers and non-drinkers (p <0.001). There were 109 (79.6%) out of 137 tea-drinkers who survived to the time of interview, compared with only 77 women (49.0%) still alive among the 157 non-tea drinkers. Compared with non-drinkers, the adjusted hazard ratios were 0.6 (95% CI 0.4-0.9) for tea-drinkers, 0.3 (95% CI 0.2-0.8) for consuming at least one cup of green tea per day, 0.4 (95%CI 0.2-0.8) for brewing at least one batch of green tea per day, and 0.3 (95% CI 0.2-0.8) for consumption of 500 grams or more dried tealeaf per year. The corresponding dose response relationships were statistically significant. Conclusion: Regular consumption of green tea post-diagnosis can enhance epithelial ovarian cancer survival. There are no previously published studies of ovarian cancer survival and tea consumption. This study has the potential to benefit many women who are diagnosed with ovarian cancer.
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Kennedy DD, Tucker KL, Ladas ED, Rheingold SR, Blumberg J, Kelly KM. Low antioxidant vitamin intakes are associated with increases in adverse effects of chemotherapy in children with acute lymphoblastic leukemia. Am J Clin Nutr. 2004 Jun;79(6):1029-36.

BACKGROUND: Chemotherapy leads to an increase in reactive oxygen species, which stresses the antioxidant defense system. Children with acute lymphoblastic leukemia rarely are overtly malnourished, which makes this population ideal for an investigation of the relations between dietary antioxidant consumption, plasma antioxidant concentrations, and chemotherapy-induced toxicity. OBJECTIVE: This study was conducted to investigate the effect of therapy on antioxidant intakes in children with acute lymphoblastic leukemia, the relation between dietary antioxidant intakes and plasma antioxidant concentrations, and the relation between the incidence of side effects due to treatment and antioxidant intake. DESIGN: We conducted a 6-mo observational study of 103 children with acute lymphoblastic leukemia. Plasma micronutrient concentrations, dietary intakes, and incidence of side effects of chemotherapy were ascertained at diagnosis and after 3 and 6 mo of therapy. RESULTS: Throughout the 6-mo study period, subjects ingested vitamin E, total carotenoid, beta-carotene, and vitamin A in amounts that were 66%, 30%, 59%, and 29%, respectively, of the US recommended dietary allowance or of the amounts specified in the third National Health and Nutrition Examination Survey. Greater vitamin C intakes at 6 mo were associated with fewer therapy delays, less toxicity, and fewer days spent in the hospital. Greater vitamin E intakes at 3 mo were associated with a lower incidence of infection. Greater beta-carotene intakes at 6 mo were associated with a decreased risk of toxicity. CONCLUSION: A large percentage of children undergoing treatment for acute lymphoblastic leukemia have inadequate intakes of antioxidants and vitamin A. Lower intakes of antioxidants are associated with increases in the adverse side effects of chemotherapy.
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Sugiyama T, Sadzuka Y. Combination of theanine with doxorubicin inhibits hepatic metastasis of M5076 ovarian sarcoma. Clin Cancer Res. 1999 Feb;5(2):413-6.

Theanine is a peculiar amino acid existing in green tea leaves, which was previously indicated to enhance the antitumor activity of doxorubicin. In the present study, the effect of combination of theanine with doxorubicin against hepatic metastasis of M5076 ovarian sarcoma was investigated. The primary tumor was significantly reduced by the combined treatment on M5076 transplanted (s.c.) mice. The liver weight of control mice increased to twice the normal level because of hepatic metastasis of M5076. In contrast, the injection of doxorubicin alone or theanine plus doxorubicin suppressed the increase in liver weight and inhibited hepatic metastasis. Moreover, the liver weights and metastasis scores demonstrated that theanine enhanced the inhibition of hepatic metastasis induced by doxorubicin. Furthermore, in vitro experiments indicated that theanine increased the intracellular concentration of doxorubicin remaining in M5076 cells. This action suggests that theanine leads the enhancement of the suppressive efficacy of doxorubicin on hepatic metastasis in vivo. Therefore, it was proved that theanine increased not only the antitumor activity on primary tumor but also the metastasis-suppressive efficacy of doxorubicin. The effect of theanine on the efficacy of antitumor agents is expected to be applicable in clinical cancer chemotherapy.
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Sugiyama T, Sadzuka Y. Theanine and glutamate transporter inhibitors enhance the antitumor efficacy of chemotherapeutic agents. Biochim Biophys Acta. 2003 Dec 5;1653(2):47-59.

Biochemical modulation has played an important role in the development of cancer chemotherapy. The combined effects of theanine, a specific amino acid in green tea, and glutamate transporter inhibitors on the antitumor activity of doxorubicin (DOX), were investigated and we clarified the biochemical mechanisms of action of these modulators.In M5076 ovarian sarcoma-bearing mice, theanine significantly enhanced the inhibitory effect of DOX on tumor growth and increased the DOX concentration in the tumor, compared to DOX-alone group. Furthermore, the oral administration of theanine or green tea similarly enhanced the antitumor activity of DOX. Moreover, the combination of theanine with DOX suppressed the hepatic metastasis of ovarian sarcoma. In contrast, an increase in DOX concentration was not observed in normal tissues, such as liver and heart. Namely, theanine did not enhance, rather it tended to normalize the increase of lipid peroxide (LPO) levels and reduction of glutathione peroxidase activity as indicators of the DOX-induced side toxicity. On the other hand, in vitro experiments proved that theanine inhibited the efflux of DOX from tumor cells, supporting a theanine-induced increase in the DOX concentration in tumors in vivo. Moreover, theanine significantly inhibited the glutamate uptake by M5076 cells similar to specific inhibitors. Two astrocytic high-affinity glutamate transporters, GLAST and GLT-1, were expressed in M5076 cells. These results suggested that the inhibition of DOX efflux was induced by theanine-mediated inhibition of glutamate transporters. The reduction in the concentration of glutamate in tumor cells caused by theanine induced decreases in the intracellular glutathione (GSH) and GS-DOX conjugate levels. As the expression of MRP5 in M5076 cells was confirmed, it is suggested that the GS-DOX conjugate was transported extracellularly via the MRP5/GS-X pump in M5076 cells and that theanine affected this route. Namely, theanine increases the concentration of DOX in a tumor in vivo through inhibition of the glutamate transporter via the GS-X pump. Similarly, dihydrokainate (DHK) and L-serine-O-sulfate (SOS), specific glutamate transporter inhibitors, indicated the enhancement of the DOX antitumor activity via inhibition of glutamate uptake. Therefore, we revealed the novel mechanism of enhancement of antitumor efficacy of DOX via the inhibition of glutamate transporters. Similarly, theanine enhanced the antitumor activities of other anthracyclines, cisplatin and irinotecan. Consequently, the modulating effect of theanine on the efficacy of antitumor agents is expected to be applicable in clinical cancer chemotherapy.
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Masuda M, Suzui M, Lim JT, Weinstein IB. Epigallocatechin-3-gallate inhibits activation of HER-2/neu and downstream signaling pathways in human head and neck and breast carcinoma cells. Clin Cancer Res. 2003 Aug 15;9(9):3486-91.

Overexpression of the HER-2/neu receptor (HER-2) is associated with a poor prognosis in patients with breast carcinoma and also in patients with head and neck squamous cell carcinoma (HNSCC). In a previous study on HNSCC cell lines, we found that epigalocathechin-3-gallate (EGCG), a major biologically active component of green tea, inhibited activation of the epidermal growth factor receptor (EGFR) and thereby inhibited EGFR-related downstream signaling pathways in HNSCC cells. In the present study, we examined the effects of EGCG on activation of the HER-2 receptor in human HNSCC and breast carcinoma cell lines that display constitutive activation of HER-2. Treatment of these cells with 10 or 30 microg of EGCG, respectively, doses that cause 50% inhibition of growth, markedly inhibited the phosphorylation of HER-2 in both cell lines. This was associated with inhibition of Stat3 activation, inhibition of c-fos and cyclin D1 promoter activity, and decreased cellular levels of the cyclin D1 and Bcl-XL proteins. Although these concentrations of EGCG are quite high, we found that concentrations of 0.1-1.0 microg/ml, which are in the range of plasma concentrations after administering a single oral dose of EGCG or a green tea extract, markedly enhanced the sensitivity of both types of cell lines to growth inhibition by Taxol, a drug frequently used in the treatment of breast carcinoma and HNSCC. These results, taken together with previous evidence that EGCG also inhibits activation of the EGFR in carcinoma cells, suggest that EGCG may be useful in treating cases of breast carcinoma and HNSCC in which activation of the EGFR and/or HER-2 plays important roles in tumor survival and growth.
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Masuda M, Suzui M, Weinstein IB. Effects of epigallocatechin-3-gallate on growth, epidermal growth factor receptor signaling pathways, gene expression, and chemosensitivity in human head and neck squamous cell carcinoma cell lines. Clin Cancer Res. 2001 Dec;7(12):4220-9.

The antitumor effects of the green tea compound epigallocatechin-3-gallate (EGCG) have not been studied in detail previously in head and neck squamous cell carcinoma (HNSCC) cells. Overexpression of the epidermal growth factor receptor (EGFR) occurs frequently in HNSCC, which is an adverse prognostic factor. Therefore, we examined in detail the molecular effects of EGCG on two human HNSCC cell lines, YCU-N861 and YCU-H891, focusing on the EGFR signaling pathway. The 70% lethal dose (IC(70)) of EGCG for both cell lines was 10 microg/ml. Treatment with EGCG increased the proportion of cells in the G(1) phase of the cell cycle and induced apoptosis. In cells treated with EGCG, there was a decrease in the cyclin D1 protein, an increase in the p21(Cip1) and p27(Kip1) proteins, and a reduction in the hyperphosphorylated form of pRB, changes that may account for the arrest in G(1). EGCG also caused a decrease in the Bcl-2 and Bcl-X(L) proteins, an increase in the Bax protein, and activation of caspase 9, suggesting that EGCG induces apoptosis via a mitochondrial pathway. Treatment with EGCG inhibited phosphorylation of the EGFR, signal transducer and activator of transcription3 (Stat3), and extracellular regulated kinase (ERK) proteins and also inhibited basal and transforming growth factor-alpha-stimulated c-fos and cyclin D1 promoter activity. EGCG at 0.1 microg/ml (a concentration found in serum after oral administration) markedly enhanced the growth-inhibitory effects of 5-fluorouracil. Taken together, these findings provide insights into molecular mechanisms of growth inhibition by EGCG and suggest that this naturally occurring compound may be useful, when used alone or in combination with other agents, in the chemoprevention and/or treatment of HNSCC.
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7

Masuda M, Suzui M, Lim JT, Deguchi A, Soh JW, Weinstein IB. Epigallocatechin-3-gallate decreases VEGF production in head and neck and breast carcinoma cells by inhibiting EGFR-related pathways of signal transduction. J Exp Ther Oncol. 2002 Nov-Dec;2(6):350-9.

In a recent study on head and neck squamous cell carcinoma (HNSCC) cells we found that epigallocatechin-3-gallate (EGCG), a major biologically active component of green tea, inhibited activation of the epidermal growth factor receptor (EGFR) and related signaling pathways. Since activation of EGFR signaling pathways is associated with angiogenesis, we examined the effects of EGCG on vascular endothelial growth factor (VEGF) production by YCU-H891 HNSCC and MDA-MB-231 breast carcinoma cell lines, because we found that both of these cell lines display autocrine activation of transforming growth factor-alpha (TGF-alpha)/EGFR signaling and produce high levels of VEGF. Treatment with EGCG inhibited the constitutive activation of the EGFR, Stat3, and Akt in both cell lines. These changes were associated with inhibition of VEGF promoter activity and cellular production of VEGF. Mechanistic studies indicated that inhibition of Stat3, but not mitogen-activated protein kinase kinase (MEK)1 or phosphatidylinositol 3'-kinase (PI3K), significantly decreased VEGF promoter activity. However, the inhibitory effects of a dominant negative Stat3 on VEGF expression was not as strong as that produced by EGCG. An analysis of alternative pathways indicated that EGCG strongly inhibited the constitutive activation of NF-kappa B in both cell lines, and an NF-kappa B inhibitor strongly inhibited VEGF production. These results suggest that EGCG inhibits VEGF production by inhibiting both the constitutive activation of Stat3 and NF-kappa B, but not extracellular-signal-regulated kinase (ERK) or Akt, in these cells. Therefore, EGCG may be useful in treating HNSCC and breast carcinoma because it can exert both antiproliferative and antiangiogenic activities.
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8

Sadzuka Y, Sugiyama T, Suzuki T, Sonobe T. Enhancement of the activity of doxorubicin by inhibition of glutamate transporter. Toxicol Lett. 2001 Sep 15;123(2-3):159-67.

Theanine enhanced doxorubicin (DOX) induced antitumor activity by increasing the concentration of DOX in the tumor through the inhibition of efflux of DOX from tumor cells. As theanine reduced the level of glutamate via suppression of the glutamate transporter in tumor cells, we studied the change in the intracellular concentration of glutathione (GSH) and the correlation with the GSH S-conjugate export (GS-X) pump. The reduction in the concentration of glutamate in tumor cells caused by theanine, induced decreases in the intracellular GSH and GS-DOX levels. The expression of MRP5 in M5076 cells, was confirmed. We concluded that the GS-DOX conjugate was transported extracellularly via the MRP5/GS-X pump in M5076 cells and that theanine affected this route. Namely, theanine increases the concentration of DOX in a tumor in vivo through inhibition of the glutamate transporter via the GS-X pump.
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9

Sadzuka Y, Sugiyama T, Sonobe T. Efficacies of tea components on doxorubicin induced antitumor activity and reversal of multidrug resistance. Toxicol Lett. 2000 Apr 3;114(1-3):155-62.

Considering of novel biochemical modulation by some foods and beverages, we have performed screening for green tea components that have enhancing effects on doxorubicin (DOX) induced antitumor activity. Components, such as caffeine, theanine, (-)-epigallocatechin gallate (EGCG) and flavonoids have inhibitory effects on the DOX efflux from Ehrlich ascites carcinoma cells. Thus, it is suggested that EGCG and flavonoids may enhance DOX induced antitumor activity and increase the DOX concentrations in tumors through the inhibition of DOX efflux. It is expected that these components in green tea exhibit low toxicity and that there are few side effects of drinking green tea in combination with an antitumor agent. We think that the intake of a favorite beverage favors a positive mental attitude of a patient and increases the efficacy of the chemotherapeutic index, and that this efficacy is useful for improving the quality of life on cancer chemotherapy. In DOX resistant P388 leukemia cell bearing mice theanine increased the DOX induced efficacy through an increase in the DOX concentrations in the tumors. Theanine attacked the same transport process for DOX in both types of cells, elevated the DOX concentration and increased the DOX induced antitumor activity.
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10 Green tea polyphenols reversed multidrug resistance of cancer cells. Mei Y, Qian F, Wei D, Liu J. Reversal of cancer multidrug resistance by green tea polyphenols. J Pharm Pharmacol. 2004 Oct;56(10):1307-14.

The aim of this study was to examine the effect and mechanism of green tea polyphenols (TP) on reversal of multidrug resistance (MDR) in a carcinoma cell line. Using the MTT assay, TP was examined for its modulating effects on the drug-resistant KB-A-1 cells and drug-sensitive KB-3-1 cells. When 10 microg mL(-1) (-)-epigallocatechin gallate (EGCG) or 40 microg mL(-1) TP were present simultaneously with doxorubicin (DOX), the IC50 of DOX on KB-A-1 cells decreased from 10.3 +/- 0.9 microg mL(-1) to 4.2 +/- 0.2 and 2.0 +/- 0.1 microg mL(-1), respectively. TP and EGCG enhanced the DOX cytotoxicity on KB-A-1 cells by 5.2- and 2.5-times, respectively, but did not show a modulating effect on KB-3-1 cells. This indicated that both TP and EGCG had reversal effects on the MDR phenotype in-vitro. A KB-A-1 cell xenograft model was established, and the effect of TP on reversing MDR in-vivo was determined. Mechanistic experiments were conducted to examine the uptake, efflux and accumulation of DOX. Cloning and expression of the nucleotide binding domain of the human MDR1 gene in Escherichia coli was established, and by using colorimetry to examine the activity of ATPase to hydrolyse ATP, the ATPase activity of target nucleotide binding domain protein was determined. TP exerted its reversal effects through the inhibition of ATPase activity, influencing the function of P-glycoprotein, and causing a decreased extrusion of anticancer drug and an increased accumulation of anticancer drug in drug resistant cells. Using reverse transcription-polymerase chain reaction, the inhibitory effect of TP on MDR1 gene expression was investigated. Down-regulation of MDR1 gene expression was the main effect, which resulted in the reversal effect of TP on the MDR phenotype. TP is a potent MDR modulator with potential in the treatment of P-glycoprotein mediated MDR cancers.
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11 Sissi C, Palumbo M. The quinolone family: from antibacterial to anticancer agents. Curr Med Chem Anti-Canc Agents. 2003 Nov;3(6):439-50.

The present review focuses on the structural modifications responsible for the transformation of an antibacterial into an anticancer agent. Indeed, a distinctive feature of drugs based on the quinolone structure is their remarkable ability to target different type II topoisomerase enzymes. In particular, some congeners of this drug family display high activity not only against bacterial topoisomerases, but also against eukaryotic topoisomerases and are toxic to cultured mammalian cells and in vivo tumor models. Hence, these cytotoxic quinolones represent an exploitable source of new anticancer agents, which might also help addressing side-toxicity and resistance phenomena. Their ability to bind metal ion co-factors represents an additional means of modulating their pharmacological response(s). Moreover, quinolones link antibacterial and anticancer chemotherapy together and provide an opportunity to clarify drug mechanism across divergent species.
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12 Navarro-Peran E, Cabezas-Herrera J, Garcia-Canovas F, Durrant MC, Thorneley RN, Rodriguez-Lopez JN. The antifolate activity of tea catechins. Cancer Res. 2005 Mar 15;65(6):2059-64.

Grupo de Investigacion de Enzimologia, Departamento de Bioquimica y Biologia Molecular A, Facultad de Biologia, Universidad de Murcia, Spain.

A naturally occurring gallated polyphenol isolated from green tea leaves, (-)-epigallocatechin gallate (EGCG), has been shown to be an inhibitor of dihydrofolate reductase (DHFR) activity in vitro at concentrations found in the serum and tissues of green tea drinkers (0.1-1.0 micromol/L). These data provide the first evidence that the prophylactic effect of green tea drinking on certain forms of cancer, suggested by epidemiologic studies, is due to the inhibition of DHFR by EGCG and could also explain why tea extracts have been traditionally used in "alternative medicine" as anticarcinogenic/antibiotic agents or in the treatment of conditions such as psoriasis. EGCG exhibited kinetics characteristic of a slow, tight-binding inhibitor of 7,8-dihydrofolate reduction with bovine liver DHFR (K(I) = 0.109 micromol/L), but of a classic, reversible, competitive inhibitor with chicken liver DHFR (K(I) = 10.3 micromol/L). Structural modeling showed that EGCG can bind to human DHFR at the same site and in a similar orientation to that observed for some structurally characterized DHFR inhibitor complexes. The responses of lymphoma cells to EGCG and known antifolates were similar, that is, a dose-dependent inhibition of cell growth (IC50 = 20 micromol/L for EGCG), G0-G1 phase arrest of the cell cycle, and induction of apoptosis. Folate depletion increased the sensitivity of these cell lines to antifolates and EGCG. These effects were attenuated by growing the cells in a medium containing hypoxanthine-thymidine, consistent with DHFR being the site of action for EGCG.
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