Green tea consumption and hematologic malignancies in Japan: the Ohsaki study

The anti-cancer effect of epigallocatechin-3-O-gallate against multiple myeloma cells is potentiated by 5,7-dimethoxyflavone

(-)-Epigallocatechin-3-O-gallate (EGCG) is one of the major components of green tea polyphenol. Previous studies have shown that EGCG induces cancer-specific cell death in vitro and in vivo without causing severe side effects. However, the anti-cancer effect of EGCG alone is limited. 5,7-dimethoxyflavone (5,7-DMF), one of the principal functional components of black ginger (Kaempferia parviflora), also exerts anti-cancer effects. Here, we show that 5,7-DMF synergistically enhances the anti-cancer effect of EGCG in multiple myeloma cells by potentiating EGCG-induced intracellular cyclic guanosine monophosphate (cGMP) production. Moreover, the combination of EGCG and 5,7-DMF induces apoptotic cell death in multiple myeloma cells, and this is accompanied by activation of the cGMP/acid sphingomyelinase (ASM)/cleaved caspase-3 pathway. In conclusion, we have shown that 5,7-DMF enhances the anti-cancer effect of EGCG by upregulating cGMP in multiple myeloma cells.

The Effects of Green Tea Catechins in Hematological Malignancies

Green tea catechins are bioactive polyphenol compounds which have attracted significant attention for their diverse biological activities and potential health benefits. Notably, epigallocatechin-3-gallate (EGCG) has emerged as a potent apoptosis inducer through mechanisms involving caspase activation, modulation of Bcl-2 family proteins, disruption of survival signaling pathways and by regulating the redox balance, inducing oxidative stress. Furthermore, emerging evidence suggests that green tea catechins can modulate epigenetic alterations, including DNA methylation and histone modifications. In addition to their apoptotic actions, ROS signaling effects and reversal of epigenetic alterations, green tea catechins have shown promising results in promoting the differentiation of leukemia cells. This review highlights the comprehensive actions of green tea catechins and provides valuable insights from clinical trials investigating the therapeutic potential of green tea catechins in leukemia treatment. Understanding these multifaceted mechanisms and the outcomes of clinical trials may pave the way for the development of innovative strategies and the integration of green tea catechins into clinical practice for improving leukemia patient outcomes.

Integrative Hematology: State of the Art

Blood cancers are a group of diseases with thus far frequently poor prognosis. Although many new drugs, including target therapies, have been developed in recent years, there is still a need to expand our therapeutic armamentarium to better deal with these diseases. Integrative hematology was conceived as a discipline that enriches the patient's therapeutic possibilities with the use of supplements, vitamins and a nutritional approach aiming at improving the response to therapies and the clinical outcome. We will analyze the substances that have proved most useful in preclinical and clinical studies in some of the most frequent blood diseases or in those where these studies are more numerous; the importance of the nutritional approach and the role of the intestinal microbiota will also be emphasized.

Phosphodiesterase 5 Inhibitor Potentiates Epigallocatechin 3-O-Gallate-Induced Apoptotic Cell Death via Activation of the cGMP Signaling Pathway in Caco-2 Cells

Epigallocatechin 3-O-gallate (EGCG) is a predominant component in green tea with various health benefits. The 67 kDa laminin receptor (67LR) is a nonintegrin cell surface receptor that is overexpressed in various types of cancer; 67LR was identified a cell surface EGCG target that plays a pivotal role in tumor growth, metastasis, and resistance to chemotherapy. However, the plasma concentration of EGCG is limited, and its molecular mechanisms remain unelucidated in colon cancer. In this study, we found that the phosphodiesterase 5 (PDE5) inhibitor, vardenafil (VDN), potentiates EGCG-induced apoptotic cell death in colon cancer cells. The combination of EGCG and VDN induced apoptosis via activation of the endothelial nitric oxide synthase/cyclic guanosine monophosphate/protein kinase Cδ signaling pathway. In conclusion, the PDE5 inhibitor, VDN, may reduce the intracellular PDE5 enzyme activity that potentiates EGCG-induced apoptotic cell death in Caco-2 cells. These results suggest that PDE5 inhibitors can be used to elevate cGMP levels to induce 67LR-mediated, cancer-specific cell death. Therefore, EGCG may be employed as a therapeutic candidate for colon cancer.

Fustin, a Flavanonol, Synergically Potentiates the Anticancer Effect of Green Tea Catechin Epigallocatechin-3-O-Gallate with Activation of the eNOS/cGMP Axis

Epigallocatechin-3-O-gallate (EGCG), a catechin present in green tea, selectively elicits apoptosis in multiple myeloma cells by activating the endothelial nitric oxide synthase (eNOS)/cyclic guanosine monophosphate (cGMP) axis. However, the effects of EGCG alone are limited. Herein, we revealed that fustin, a flavanonol, enhances the EGCG-elicited activation of the cGMP/eNOS axis in multiple myeloma cells. Isobologram analysis demonstrated that EGCG/fustin synergistically elicited cell death in multiple myeloma cells. Importantly, this chemical combination significantly promoted cell death without affecting the normal cells. To assess the effects of EGCG and fustin in vivo, female BALB/c mice were inoculated with multiple myeloma MPC11 cells and then treated with each compound. The combination of EGCG/fustin suppressed tumor growth in vivo without affecting alanine aminotransferase/aspartate aminotransferase levels, the dose-limiting toxicity of EGCG. Consistent with in vitro findings, this combination increased eNOS phosphorylation at Ser1177 in the tumor. Collectively, fustin amplified EGCG-induced activation of the eNOS/cGMP axis.

Updated review on green tea polyphenol epigallocatechin-3-gallate as a cancer epigenetic regulator

In-depth insights in cancer biology over the past decades have highlighted the important roles of epigenetic mechanisms in the initiation and progression of tumorigenesis. The cancer epigenome usually experiences multiple alternations, including genome-wide DNA hypomethylation and site-specific DNA hypermethylation, various histone posttranslational modifications, and dysregulation of non-coding RNAs (ncRNAs). These epigenetic changes are plastic and reversible, and could potentially occur in the early stage of carcinogenesis preceding genetic mutation, offering unique opportunities for intervention therapies. Therefore, targeting the cancer epigenome or cancer epigenetic dysregulation with some selected agents (called epi-drugs) represents an evolving and promising strategy for cancer chemoprevention and therapy. Phytochemicals, as a class of pleiotropic molecules, have manifested great potential in modulating different cancer processes through epigenetic machinery, of which green tea polyphenol epigallocatechin-3-gallate (EGCG) is one of the most extensively studied. In this review, we first summarize epigenetic events involved in the pathogenesis of cancer, including DNA/RNA methylations, histone modifications and ncRNAs' dysregulations. We then focus on the recently discovered roles of phytochemicals, with a special emphasis on EGCG, in modulating different cancer processes through regulating epigenetic machinery. We finally discuss limitations of EGCG as an epigenetic modulator for cancer chemoprevention and treatment and offer potential strategies to overcome the shortcomings.

Src Mediates Epigallocatechin-3-O-Gallate-Elicited Acid Sphingomyelinase Activation

Epigallocatechin-3-O-gallate (EGCG) is one of the major bioactive compounds known to be present in green tea. We previously reported that EGCG shows selective toxicity through activation of the protein kinase B (Akt)/cyclic guanosine monophosphate (cGMP)/acid sphingomyelinase (ASM) axis via targeting its receptor 67-kDa laminin receptor (67LR), which is overexpressed in cancer. However, little is known about upstream mechanisms of EGCG-elicited ASM activation. In this study we show that the proto-oncogene tyrosine-protein kinase Src, also known as c-src, plays a crucial role in the anticancer effect of EGCG. We showed that EGCG elicits phosphorylation of Src at Tyr 416, a crucial phosphorylation site for its activity, and that the pharmacological inhibition of Src impedes the upstream events in EGCG-induced cell death signaling including upregulation of Akt activity, increase in cGMP levels, and activation of ASM. Moreover, focal adhesion kinase (FAK), which is involved in the phosphorylation of Src, is colocalized with 67LR. EGCG treatment enhanced interaction of FAK and 67LR. Consistent with these findings, pharmacological inhibition of FAK significantly neutralized EGCG-induced upregulation of Akt activity and activation of ASM. Taken together, FAK/Src play crucial roles in the upstream signaling of EGCG.

Green tea (Camellia sinensis) for the prevention of cancer

BACKGROUND

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews (2009, Issue 3).Tea is one of the most commonly consumed beverages worldwide. Teas from the plant Camellia sinensis can be grouped into green, black and oolong tea, and drinking habits vary cross-culturally. C sinensis contains polyphenols, one subgroup being catechins. Catechins are powerful antioxidants, and laboratory studies have suggested that these compounds may inhibit cancer cell proliferation. Some experimental and nonexperimental epidemiological studies have suggested that green tea may have cancer-preventative effects.

OBJECTIVES

To assess possible associations between green tea consumption and the risk of cancer incidence and mortality as primary outcomes, and safety data and quality of life as secondary outcomes.

SEARCH METHODS

We searched eligible studies up to January 2019 in CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and reference lists of previous reviews and included studies.

SELECTION CRITERIA

We included all epidemiological studies, experimental (i.e. randomised controlled trials (RCTs)) and nonexperimental (non-randomised studies, i.e. observational studies with both cohort and case-control design) that investigated the association of green tea consumption with cancer risk or quality of life, or both.

DATA COLLECTION AND ANALYSIS

Two or more review authors independently applied the study criteria, extracted data and assessed methodological quality of studies. We summarised the results according to diagnosis of cancer type.

MAIN RESULTS

In this review update, we included in total 142 completed studies (11 experimental and 131 nonexperimental) and two ongoing studies. This is an additional 10 experimental and 85 nonexperimental studies from those included in the previous version of the review. Eleven experimental studies allocated a total of 1795 participants to either green tea extract or placebo, all demonstrating an overall high methodological quality based on 'Risk of bias' assessment. For incident prostate cancer, the summary risk ratio (RR) in the green tea-supplemented participants was 0.50 (95% confidence interval (CI) 0.18 to 1.36), based on three studies and involving 201 participants (low-certainty evidence). The summary RR for gynaecological cancer was 1.50 (95% CI 0.41 to 5.48; 2 studies, 1157 participants; low-certainty evidence). No evidence of effect of non-melanoma skin cancer emerged (summary RR 1.00, 95% CI 0.06 to 15.92; 1 study, 1075 participants; low-certainty evidence). In addition, adverse effects of green tea extract intake were reported, including gastrointestinal disorders, elevation of liver enzymes, and, more rarely, insomnia, raised blood pressure and skin/subcutaneous reactions. Consumption of green tea extracts induced a slight improvement in quality of life, compared with placebo, based on three experimental studies. In nonexperimental studies, we included over 1,100,000 participants from 46 cohort studies and 85 case-control studies, which were on average of intermediate to high methodological quality based on Newcastle-Ottawa Scale 'Risk of bias' assessment. When comparing the highest intake of green tea with the lowest, we found a lower overall cancer incidence (summary RR 0.83, 95% CI 0.65 to 1.07), based on three studies, involving 52,479 participants (low-certainty evidence). Conversely, we found no association between green tea consumption and cancer-related mortality (summary RR 0.99, 95% CI 0.91 to 1.07), based on eight studies and 504,366 participants (low-certainty evidence). For most of the site-specific cancers we observed a decreased RR in the highest category of green tea consumption compared with the lowest one. After stratifying the analysis according to study design, we found strongly conflicting results for some cancer sites: oesophageal, prostate and urinary tract cancer, and leukaemia showed an increased RR in cohort studies and a decreased RR or no difference in case-control studies.

AUTHORS' CONCLUSIONS

Overall, findings from experimental and nonexperimental epidemiological studies yielded inconsistent results, thus providing limited evidence for the beneficial effect of green tea consumption on the overall risk of cancer or on specific cancer sites. Some evidence of a beneficial effect of green tea at some cancer sites emerged from the RCTs and from case-control studies, but their methodological limitations, such as the low number and size of the studies, and the inconsistencies with the results of cohort studies, limit the interpretability of the RR estimates. The studies also indicated the occurrence of several side effects associated with high intakes of green tea. In addition, the majority of included studies were carried out in Asian populations characterised by a high intake of green tea, thus limiting the generalisability of the findings to other populations. Well conducted and adequately powered RCTs would be needed to draw conclusions on the possible beneficial effects of green tea consumption on cancer risk.

Epigallocatechin-3-O-gallate induces acid sphingomyelinase activation through activation of phospholipase C

Epigallocatechin-3-O-gallate (EGCG)-induced cyclic guanosine monophosphate (cGMP) plays a crucial role in EGCG-induced cell death in various types of cancer cells. However, little is known regarding the early molecular events after cGMP induction. In this study, we showed that cGMP induction is sufficient to induce the phosphorylation of protein kinase C delta (PKCδ) at Ser664, the crucial kinase for EGCG-induced activation of acid sphingomyelinase (ASM). Using a chemical inhibitor library, we revealed that the inhibitors of the negative regulators of diacylglycerol strongly increase the effect of EGCG. We also showed that EGCG treatment increased phospholipase C (PLC) activity, and the same results were obtained with cGMP inducer treatment. EGCG-induced ASM activation was completely suppressed by pharmacological inhibition of PLC. Collectively, EGCG-induced cGMP activated the cGMP/PLC/PKCδ/ASM signaling axis in multiple myeloma cells.

Green tea consumption and risk of hematologic neoplasms: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study)

PURPOSE

Experimental studies suggested that green tea may have an anticancer effect on hematologic neoplasms. However, few prospective studies have been conducted.

METHODS

A total of 65,042 individuals aged 40-79 years participated in this study and completed a self-administered questionnaire about their lifestyle and medical history at baseline (1988-1990). Of these, 52,462 individuals living in 24 communities with information on incident hematologic neoplasms available in the cancer registry, who did not have a history of cancer and provided valid information on frequency of green tea consumption, were followed through 2009. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the incidence of hematologic neoplasms according to green tea consumption were analyzed.

RESULTS

The incidence of hematologic neoplasms during a median follow-up of 13.3 years was 323. Compared with the never-drinkers of green tea, the multivariate HRs and 95% CIs for total hematologic neoplasms in green tea drinkers of ≤ 2 cups/day, 3-4 cups/day, and ≥ 5 cups/day were 0.65 (0.42-1.00), 0.73 (0.47-1.13), and 0.63 (0.42-0.96), respectively. The association was more prominent for acute myeloid leukemias and follicular lymphomas.

CONCLUSIONS

The present cohort study suggests a protective effect of green tea against hematologic neoplasms, especially acute myeloid leukemias.

Coffee and green tea consumption and subsequent risk of acute myeloid leukemia and myelodysplastic syndromes in Japan

Although coffee and green tea are suggested to reduce the risk of some types of cancers, only a few epidemiological studies have investigated their effect on the risk of acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Here, we investigated the association of coffee and green tea consumption and the risk of AML and MDS in a large-scale population-based cohort study in Japan. A total of 95,807 Japanese subjects (45,937 men and 49,870 women; age 40-69 years at baseline) were followed to the end of 2012, for an average of 18 years. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between coffee and green tea consumption at baseline and the risk of AML and MDS were assessed using a Cox proportional hazards model with adjustment for potential confounders. During 1,751.956 person-years, we identified 85 AML cases and 70 MDS cases. Our findings showed no significant association between coffee consumption and the risk of AML, or between green tea consumption and the risk of AML or MDS. In contrast, we observed a decreasing dose-response relationship between coffee consumption and the risk of MDS among men (almost none: reference, 1-4 times/week: HR = 0.83, 95% CI: 0.43-1.62; ≥1cups/day: HR = 0.47, 0.22-0.99, p for trend = 0.049). Stratified analysis by smoking status suggested that the observed relative risk for AML and MDS of coffee drinkers relative to non-coffee drinkers might be due to residual confounding by smoking. These findings deserve further investigation in future studies.

Complementary and Integrative Medicine in Hematologic Malignancies: Questions and Challenges

Hematologic malignancies represent 9.7% of all cancers, making them the fourth most common type of cancer in the United States. The aggressive and complex treatments administered in hematologic malignancies result in a high burden of psychological needs. Complementary and integrative medicine (CIM) is becoming one of the options that patients use to address their distress during and after cancer treatments. It is not clear whether appropriate CIM can relieve distress in patients affected by these malignancies. This review covers the potential benefits of CIM as relates to nutrition, nutritional supplements, exercise, circadian rhythm, methods for reducing distress during bone marrow aspiration, massage therapy, and acupuncture, in treating patients with hematological malignancies. This review may provide a framework to enhance patient-doctor dialogue regarding CIM use in hematologic malignancies.

Green Tea Polyphenol EGCG Upregulates Tollip Expression by Suppressing Elf-1 Expression

TLR signaling is critical to innate immune system regulation; however, aberrant TLR signaling is involved in several diseases, including insulin resistance, Alzheimer's disease, and tumor metastasis. Moreover, a recent study found that TLR-4 signaling pathway inhibition might be a target for the suppression of chronic inflammatory disorders. In this article, we show that the green tea polyphenol epigallocatechin-3-O-gallate (EGCG) increases the expression of Toll interacting protein, a strong inhibitor of TLR4 signaling, by suppressing the expression of E74-like ETS transcription factor 1 (Elf-1). A mechanistic study revealed that EGCG suppressed Elf-1 expression via protein phosphatase 2A/cyclic GMP (cGMP)-dependent mechanisms. We also confirmed that orally administered EGCG and a cGMP inducer upregulated Toll interacting protein expression, increased intracellular levels of cGMP in macrophages, and suppressed Elf-1 expression. These data support EGCG and a cGMP inducer as potential candidate suppressors of TLR4 signaling.

Coffee and Green Tea Consumption and Subsequent Risk of Malignant Lymphoma and Multiple Myeloma in Japan: The Japan Public Health Center-based Prospective Study

Background: The aim of this study was to investigate the association of coffee and green tea consumption and the risk of malignant lymphoma and multiple myeloma in a large-scale population-based cohort study in Japan.Methods: In this analysis, a total of 95,807 Japanese subjects (45,937 men and 49,870 women; ages 40-69 years at baseline) of the Japan Public Health Center-based Prospective Study who completed a questionnaire about their coffee and green tea consumption were followed up until December 31, 2012, for an average of 18 years. HRs and 95% confidence intervals were estimated using a Cox regression model adjusted for potential confounders as a measure of association between the risk of malignant lymphoma and multiple myeloma associated with coffee and green tea consumption at baseline.Results: During the follow-up period, a total of 411 malignant lymphoma cases and 138 multiple myeloma cases were identified. Overall, our findings showed no significant association between coffee or green tea consumption and the risk of malignant lymphoma or multiple myeloma for both sexes.Conclusions: In this study, we observed no significant association between coffee or green tea consumption and the risk of malignant lymphoma or multiple myeloma.Impact: Our results do not support an association between coffee or green tea consumption and the risk of malignant lymphoma or multiple myeloma. Cancer Epidemiol Biomarkers Prev; 26(8); 1352-6. ©2017 AACR.

Hydrogen sulphide donors selectively potentiate a green tea polyphenol EGCG-induced apoptosis of multiple myeloma cells

Hydrogen sulphide (H₂S) is a colourless gas with the odour of rotten eggs and has recently been recognized as a signal mediator in physiological activities related with the regulation of homeostasis, the vascular system and the inflammatory system. Here we show that H₂S donors, including sodium hydrogen sulphide (NaHS), GYY 4137 and diallyltrisulfide (DATS), synergistically enhanced the anti-cancer effect of a green tea polyphenol (−)-epigallocatechin-3-O-gallate (EGCG) against multiple myeloma cells without affecting normal cells. NaHS significantly potentiated the anti-cancer effect of EGCG and prolonged survival in a mouse xenograft model. In this mechanism, H₂S enhanced apoptotic cell death through cyclic guanosine monophosphate (cGMP)/acid sphingomyelinase pathway induced by EGCG. Moreover, NaHS reduced the enzyme activity of cyclic nucleotide phosphodiesterase that is known as cGMP negative regulator. In conclusion, we identified H₂S as a gasotransmitter that potentiates EGCG-induced cancer cell death.

Green tea polyphenol epigallocatechin-O-gallate induces cell death by acid sphingomyelinase activation in chronic myeloid leukemia cells

An epidemiological study showed that green tea consumption is associated with a reduced risk of hematopoietic malignancy. The major green tea polyphenol epigallocatechin-3-O-gallate (EGCG) is reported to have anticancer effects. Chronic myeloid leukemia (CML) is a major hematopoietic malignancy characterized by expansion of myeloid cells. In the present study, we showed EGCG-induced acid sphingomyelinase (ASM) activation and lipid raft clustering in CML cells. The ASM inhibitor desipramine significantly reduced EGCG-induced cell death. Protein kinase Cδ is a well-known kinase that plays an important role in ASM activation. We observed EGCG-induced phos-phorylation of protein kinase Cδ at Ser664. Importantly, EGCG-induced ASM activation was significantly reduced by pretreatment of CML cells with the soluble guanylate cyclase inhibitor NS2028, suggesting that EGCG induced ASM activation through the cyclic guanosine monophosphate (cGMP)-dependent pathway. Indeed, pharmacological inhibition of a cGMP-negative regulator enhanced the anti-CML effect of EGCG. These results indicate that EGCG-induced cell death via the cGMP/ASM pathway in CML cells.

Metabolic profiling-based data-mining for an effective chemical combination to induce apoptosis of cancer cells

Green tea extract (GTE) induces apoptosis of cancer cells without adversely affecting normal cells. Several clinical trials reported that GTE was well tolerated and had potential anti-cancer efficacy. Epigallocatechin-3-O-gallate (EGCG) is the primary compound responsible for the anti-cancer effect of GTE; however, the effect of EGCG alone is limited. To identify GTE compounds capable of potentiating EGCG bioactivity, we performed metabolic profiling of 43 green tea cultivar panels by liquid chromatography-mass spectrometry (LC-MS). Here, we revealed the polyphenol eriodictyol significantly potentiated apoptosis induction by EGCG in vitro and in a mouse tumour model by amplifying EGCG-induced activation of the 67-kDa laminin receptor (67LR)/protein kinase B/endothelial nitric oxide synthase/protein kinase C delta/acid sphingomyelinase signalling pathway. Our results show that metabolic profiling is an effective chemical-mining approach for identifying botanical drugs with therapeutic potential against multiple myeloma. Metabolic profiling-based data mining could be an efficient strategy for screening additional bioactive compounds and identifying effective chemical combinations.

Green tea catechin, epigallocatechin-3-gallate, attenuates the cell viability of human non-small-cell lung cancer A549 cells via reducing Bcl-xL expression

Clinical and epidemiological studies have indicated that the consumption of green tea has a number of beneficial effects on health. Epigallocatechin-3-gallate (EGCg), the major polyphenolic compound present in green tea, has received much attention as an active ingredient. Among the numerous promising profiles of EGCg, the present study focused on the anticancer effects. Apoptosis induced by EGCg and subsequent cell growth suppression have been demonstrated in a number of cell culture studies. However, the underlying mechanism of apoptotic cell death remains unclear. Thus, the aim of the present study was to identify the major molecule that mediates proapoptotic cell death by EGCg. The effect of EGCg on cell proliferation and the induction of mRNA that modulates apoptotic cell death was evaluated in the A549 human non-small-cell lung cancer cell line. In addition, morphological changes were assessed by microscopy in A549 cells that had been treated with 100 μM EGCg for 24 h. The MTT assay revealed that cell proliferation was significantly reduced by EGCg in a dose-dependent manner (3–100 μM). The mRNA expression level of B-cell lymphoma-extra large (Bcl-xL) was decreased in A549 cells following 24 h incubation with 100 μM EGCg. Therefore, the results indicated that the inhibition of cell proliferation by EGCg may be achieved via suppressing the expression of the cell death-inhibiting gene, Bcl-xL.

Phosphodiesterase 5 inhibitor acts as a potent agent sensitizing acute myeloid leukemia cells to 67-kDa laminin receptor-dependent apoptosis

(-)-Epigallocatechin-3-O-gallate (EGCG), a polyphenol in green tea, induces apoptosis in acute myeloid leukemia (AML) cells without affecting normal cells. In this study, we observed that cGMP acts as a cell death mediator of the EGCG-induced anti-AML effect through acid sphingomyelinase activation. EGCG activated the Akt/eNOS axis, a well-known mechanism in vascular cGMP upregulation. We also observed that a major cGMP negative regulator, phosphodiesterase 5, was overexpressed in AML cells, and PDE5 inhibitor, an anti-erectile dysfunction drug, synergistically enhanced the anti-AML effect of EGCG. This combination regimen killed AML cells via overexpressed 67-kDa laminin receptors.

Phase 2 trial of daily, oral Polyphenon E in patients with asymptomatic, Rai stage 0 to II chronic lymphocytic leukemia

BACKGROUND

The objective of the current study was to follow up the results of phase 1 testing by evaluating the clinical efficacy of the green tea extract Polyphenon E for patients with early stage chronic lymphocytic leukemia (CLL).

METHODS

Previously untreated patients with asymptomatic, Rai stage 0 to II CLL and an absolute lymphocyte count (ALC) ≥ 10 × 10(9) /L were eligible for this phase 2 trial. Polyphenon E with a standardized dose of epigallocatechin gallate (EGCG) (2000 mg per dose) was administered twice daily.

RESULTS

A total of 42 patients received Polyphenon E at a dose of 2000 mg twice daily for up to 6 months. Of these patients, 29 (69%) had Rai stage I to II disease. Patients received a median of 6 cycles of treatment (range, 1 cycle-6 cycles). The most common grade 3 side effects (according to National Cancer Institute Common Terminology Criteria for Adverse Events) were transaminitis (1 patient), abdominal pain (1 patient), and fatigue (1 patient). Clinical activity was observed, with 13 patients (31%) experiencing a sustained reduction of ≥ 20% in the ALC and 20 of 29 patients (69%) with palpable adenopathy experiencing at least a 50% reduction in the sum of the products of all lymph node areas. EGCG plasma levels after 1 month of therapy were found to be correlated with reductions in lymphadenopathy (correlation co-efficient, 0.44; P = .02). Overall, 29 patients (69%) fulfilled the criteria for a biologic response with either a sustained decline ≥ 20% in the ALC and/or a reduction ≥ 30% in the sum of the products of all lymph node areas at some point during the 6 months of active treatment.

CONCLUSIONS

Daily oral EGCG in the Polyphenon E preparation was well tolerated by patients with CLL in this phase 2 trial. Durable declines in the ALC and/or lymphadenopathy were observed in the majority of patients.

Gamma-glutamyltransferase and cancer incidence: the Ohsaki cohort study

Background

Although experimental studies have shown that gamma-glutamyltransferase (GGT) has a role in tumor progression, epidemiologic evidence for a relationship between GGT and cancer incidence is limited. The present study investigated the association between GGT and cancer incidence and assessed the role of alcohol consumption in this association.

Methods

We examined a cohort of 15 031 Japanese adults aged 40 to 79 years who attended a health checkup in 1995 and were free of cancer at that time. GGT was measured using the Szasz method. The participants were then followed from 1 January 1996 until 31 December 2005, and cancer incidence was recorded by using the Miyagi Regional Cancer Registry. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed for each quartile of GGT and compared. The lowest quartile (GGT <13.0 IU/ml) was used as the reference category.

Results

We documented 1505 cancers. Among participants in the highest quartile (GGT ≥31.0 IU/ml), the multivariate HR for any cancer was 1.28 (95% CI, 1.08–1.53; P for trend, <0.001), the HR for colorectal cancer was significantly greater than unity, and the HRs for esophageal, pancreatic, and breast cancers were greater than unity but not significantly so. This positive trend was observed only in current drinkers.

Conclusions

Our findings suggest that there is a positive relationship between GGT and cancer incidence only for alcohol-related cancers in current drinkers and that the positive association of GGT with cancer incidence largely reflects alcohol consumption.

Citrus consumption and cancer incidence: the Ohsaki cohort study

Basic research and case-control studies have suggested that citrus consumption may protect against cancer. However, the protective effect has been observed from few prospective studies. This study investigated the association of citrus consumption with cancer incidence among 42,470 Japanese adults in the Ohsaki National Health Insurance Cohort, which covered an age range of 40-79 years, and was followed up from 1995 to 2003 for all-cancer and individual cancer incidence. Citrus consumption was assessed using a self-administered questionnaire. The Cox proportional hazard model was applied to estimate relative risks (RRs) and 95% CIs. During the 323,204 person-years of follow-up, 3,398 cases were identified totally. Citrus consumption, especially daily consumption, was correlated with reduced all-cancer incidence, the RRs were 0.89 (95% CI = 0.80-0.98) for total participants, 0.86 (0.76-0.98) for males and 0.93 (0.79-1.09) for females, as well as multiple cancers at individual sites, especially pancreatic (RR = 0.62, 95% CI = 0.38-1.00) and prostate cancer (RR = 0.63, 95% CI = 0.41-0.97). Joint effect analysis showed a reduced risk of overall cancer existed only for subjects who consumed >or=1 cup green tea/day (RR = 0.83, 95% CI = 0.73-0.93) as well as for males (RR = 0.83, 95% CI = 0.71-0.97) or females (RR = 0.82, 95% CI = 0.68-0.99). These findings suggest that citrus consumption is associated with reduced all-cancer incidence, especially for subjects having simultaneously high green tea consumption. Further work on the specific citrus constituents is warranted, and clinical trials are ultimately necessary to confirm the protective effect.