Antitumor effect of green tea polyphenol epigallocatechin-3-gallate in ovarian carcinoma cells: evidence for the endothelin-1 as a potential target

The green tea polyphenol, epigallocatechin-3-gallate (EGCG), has been shown to prevent cancer; however, a precise mechanism responsible for tumor growth inhibition has not yet been clearly described. The endothelin (ET) A receptor (ET(A)R)/ET-1 autocrine pathway is overexpressed in ovarian carcinoma and triggers tumor growth, neoangiogenesis, and invasion. These latter tumor-promoting effects are mediated through the activation of cyclooxygenase (COX)-1- and COX-2-dependent pathways by ET-1. In the present study, pretreatment of HEY and OVCA 433 ovarian carcinoma cell lines with green tea and EGCG inhibited ET-1/ET(A)R expression, ET(A)R-mediated COX-1/2 mRNA expression, and COX-2 promoter activity. These effects were associated with a significant reduction in the COX-1/2-derived prostaglandin E2 (PGE2) production. These results provide a novel insight into the mechanism by which EGCG, by affecting ET(A)R-dependent COX-1/2 pathways may inhibit ovarian tumors suggesting that EGCG may be useful in preventing and treating ovarian carcinoma in which activation of ET(A)R by ET-1 plays a critical role in tumor growth and progression.     

Induction of apoptosis by epigallocatechin-3-gallate in human lymphoblastoid B cells

(-)-Epigallocatechin-3-gallate (EGCG), a major constituent of green tea polyphenols, has been shown to suppress cancer cell proliferation and induce apoptosis. In this study we investigated its efficacy and the mechanism underlying its effect using human B lymphoblastoid cell line Ramos, and effect of co-treatment with EGCG and a chemotherapeutic agent on apoptotic cell death. EGCG induced dose- and time-dependent apoptotic cell death accompanied by loss of mitochondrial transmembrane potential, release of cytochrome c into the cytosol, and cleavage of pro-caspase-9 to its active form. EGCG also enhanced production of intracellular reactive oxygen species (ROS). Pretreatment with diphenylene iodonium chloride, an inhibitor of NAD(P)H oxidase and an antioxidant, partially suppressed both EGCG-induced apoptosis and production of ROS, implying that oxidative stress is involved in the apoptotic response. Furthermore, we showed that combined-treatment with EGCG and a chemotherapeutic agent, etoposide, synergistically induced apoptosis in Ramos cells.     

Regulation of nodularin-induced apoptosis by epigallocatechin-3-gallate on fish lymphocytes in vitro

Nodularin is one of the most conspicuous and widespread pollutants that elicit water ecological hazards to fish, causing serious damage on the immune system and physiological functions. Nodularin can cause oxidative stress-induced apoptosis on fish lymphocytes. The regulatory effects of epigallocatechin-3-gallate (EGCG) at 10, 100, and 1000 μg/L levels on the antioxidant defense system and apoptosis of Carassius auratus lymphocytes exposed to a high dose of nodularin (100 μg/L) were quantified in vitro. EGCG reduced nodularin-induced oxidative damage on fish immune cells. This compound significantly increased the activities of superoxide dismutase and catalase and the level of glutathione but decreased the levels of intracellular reactive oxygen species and malondialdehyde. Flow cytometry results showed that the percentages of apoptotic cells after treatment with 10, 100, and 1000 μg/L EGCG for 12 h reached 27.9%, 19.1%, and 13.7%, respectively. By contrast, the nodularin alone-induced group showed a high percentage of apoptosis (44.2%). Western blot analysis showed the increased expression of bcl-2 and the decreased expression of bax and caspase-3 in EGCG-treated fish lymphocytes. EGCG also inhibited the potential collapse of the mitochondrial membrane. Overall, EGCG can inhibit nodularin-induced apoptosis and protect the normal immunity of fish by regulating bax/bcl-2 and blocking the downstream of mitochondrial apoptosis pathway with increased intracellular antioxidant enzyme activity.     

Effects of epigallocatechin-3-gallate (EGCG) on in vitro maturation and fertilization of porcine oocytes

The beneficial properties of green tea and especially of its principal active polyphenol, epigallocatechin-3-gallate (EGCG), have led to an increased demand for dietary supplements with highly enriched EGCG concentrations. In order to investigate the possible reproductive-related consequence of EGCG supplementation, the effects of this catechin on in vitro maturation (IVM) and fertilization (IVF) of oocyte, using the pig as experimental model, were examined. In the first series of experiments EGCG, at concentrations ranging from 0 to 25 microg/ml, was added during in vitro maturation of pig oocytes. EGCG had no effect on nuclear maturation of pig oocytes and on fertilization traits considered after IVF at any of the doses tested. By contrast, a significant (p<0.05) decrease in the number of embryos that developed to blastocysts following parthenogenetic activation was recorded when 25 microg/ml EGCG was added to IVM medium; in addition this catechin concentration significantly (p<0.05) inhibited progesterone production by cumulus cells after 48 h of culture. When induction of sperm capacitation was performed in presence of EGCG, a significantly lower percentage of spermatozoa showing a Hsp70-capacitated pattern and a significant reduction of sperm H(2)O(2) production were evident at a concentration of 25 microg/ml EGCG (p<0.05). During gamete coincubation EGCG reduced, in a dose response manner, the number of reacted spermatozoa suspended in fertilization medium and increased the number of sperm bound to ZP. Supplementation of 10 microg/ml EGCG during IVF significantly increased the fertilization rate while higher EGCG concentrations (25 microg/ml) decreased the percentage of fertilized oocytes (p<0.05). In conclusion, our data suggest that high EGCG concentrations could affect in vitro maturation and fertilization in pig; it cannot be totally excluded that excessive EGCG concentrations could induce reproductive-related consequences also in vivo.     

Anti-proliferative effects of a novel isoflavone derivative in medullary thyroid carcinoma: An in vitro study

Currently available treatments for patients with medullary thyroid carcinoma (MTC) with residual or recurrent disease after primary surgery have low efficacy rates. In view of the possible role of estrogen in the development of thyroid neoplasia, we explored whether proliferation of the human MTC TT cell line, might be curbed by carboxy-daidzein-tBoc (cD-tBoc), a novel isoflavone derivative. Estrogen receptor (ER) α mRNA expression in TT cells was more abundant than ERβ, with a ratio of 48:1. Estradiol-17β (E2) increased DNA synthesis in a dose dependent manner. [(3)H]-thymidine incorporation was also stimulated by the ERβ agonist DPN and the ERα agonist PPT. cD-tBoc inhibited TT cell growth as assessed by thymidine incorporation, XTT assay, and microscopic analysis of culture wells. Creatine kinase specific activity, a marker of the modulatory effects of estrogen on cell energy metabolism, was likewise inhibited. The inhibitory effect of cD-tBoc on [(3)H]-thymidine incorporation could be blocked by the ERβ antagonist PTHPP but not by the ERα antagonist MPP, suggesting that the antiproliferative effect of cD-tBoc on these cells is mediated through ERβ. Furthermore, cD-tBoc potently increased apoptosis and cell necrosis. Co-incubation with the antiapoptotic agent Z-VAD-FMK reversed the growth inhibitory effect elicited by cD-tBoc. These results support the hypothesis that estrogens are involved in the proliferation of MTC. The potent anti-proliferative effects mediated by isoflavone derivatives in the human MTC cell line TT suggest and that this property may be utilized to design effective anti-neoplastic agents.     

Anti-proliferative and differentiation-inducing activities of the green tea catechin epigallocatechin-3-gallate (EGCG) on the human eosinophilic leukemia EoL-1 cell line

A novel approach for the treatment of leukemia is the differentiation therapy in which immature leukemia cells are induced to attain a mature phenotype when exposed to differentiation inducers, either alone or in combinations with other chemotherapeutic or chemopreventive drugs. Over the past decade, numerous studies indicated that green tea catechins (GTC) could suppress the growth and induce apoptosis on a number of human cancer cell lines. However, the differentiation-inducing activity of GTC on human tumors remains poorly understood. In the present study, the effect of the major GTC epigallocatechin-3-gallate (EGCG) on the proliferation and differentiation of a human eosinophilc leukemic cell line, EoL-1, was examined. Our results showed that EGCG suppressed the proliferation of the EoL-1 cells in a dose-dependent manner, with an estimated IC(50) value of 31.5 microM. On the other hand, EGCG at a concentration of 40 microM could trigger the EoL-1 cells to undergo morphological differentiation into mature eosinophil-like cells. Using RT-PCR and flow cytometry, it was found that EGCG upregulated the gene and protein expression of two eosinophil-specific granule proteins, the major basic protein (MBP) and eosinophil peroxidase (EPO), in EoL-1 cells. Taken together, our findings suggest that EGCG can exhibit anti-leukemic activity on a human eosinophilic cell line EoL-1 by suppressing the proliferation and by inducing the differentiation of the leukemia cells.     

Anti-proliferative effects of heating on the human prostatic carcinoma cells in culture

Prostatic cancers are well-known to be sensitive to heat stress. However, the mechanism by which the cancer cells are killed by high temperature remains poorly understood. The present study was undertaken to determine the anti-proliferative effects of heat stress on the prostatic cancer cells in culture. Heat shock at 43 degrees C inhibited the cell growth of three different prostatic cell lines. Flow cytometrical analysis using BrdU and PI showed a decrease in the proportion of cells in an S phase, accompanied by cell accumulation in G1 and G2, in both JCA-1 and PC-3 but not in LNcap. Both JCA-1 and PC-3 presented a strong expression of hsp70 at 37 degrees C. The heat shock caused apparent enhancement of the expression of hsp70 through the cell cycle. A treatment at 43 degrees C for 8 hours resulted in not only an apparent increment of positive hsp70 cells, but cells with subdiploid DNA content in LNcap. Flow cytometrical analysis by FITC-labeled Annexin V showed increment of apoptotic cells at 43 degrees C for 8 hours in LNcap cells. The results suggest that apoptosis is an important pathway of heat-induced killing of these cells. In conclusion, the cell growth of prostatic cancers may be affected by the temperature through relationship of the cell cycle and hsp70.     

Green tea polyphenol epigallocatechin-3-gallate inhibits oxidative damage and preventive effects on carbon tetrachloride-induced hepatic fibrosis

The aim of the study was to examine the effects of epigallocatechin-3-gallate (EGCG) on hepatic fibrogenesis and on cultured hepatic stellate cells (HSCs). The rat model of carbon tetrachloride (CCl₄)-induced hepatic fibrosis was used to assess the effect of daily intraperitoneal injections of EGCG on the indexes of fibrosis. Histological and hepatic hydroxyproline examination revealed that EGCG significantly arrested progression of hepatic fibrosis. EGCG caused significant amelioration of liver injury (reduced activities of serum alanine aminotransferase and aspartate aminotransferase). The development of CCl₄-induced hepatic fibrosis altered the redox state with a decreased hepatic glutathione and increased the formation of lipid peroxidative products, which were partially normalized by treatment with EGCG, respectively. Moreover, EGCG markedly attenuated HSC activation as well as matrix metalloproteinase (MMP)-2 activity. In cultured stellate cell, the expression of MMP-2 mRNA and protein were substantially reduced by EGCG treatment. Concanavalin A-induced activation of secreted MMP-2 was inhibited by EGCG through the influence of membrane type 1-MMP activity. These results demonstrate that administration of EGCG may be useful in the treatment and prevention of hepatic fibrosis.     

Theaflavin and epigallocatechin-3-gallate synergistically induce apoptosis through inhibition of PI3K/Akt signaling upon depolymerizing microtubules in HeLa cells

Theaflavin (TF) and epigallocatechin-3-gallate (EGCG) both have been reported previously as microtubule depolymerizing agents that also have anticancer effects on various cancer cell lines and in animal models. Here, we have applied TF and EGCG in combination on HeLa cells to investigate if they can potentiate each other to improve their anticancer effect in lower doses and the underlying mechanism. We found that TF and EGCG acted synergistically, in lower doses, to inhibit the growth of HeLa cells. We found the combination of 50 µg/mL TF and 20 µg/mL EGCG to be the most effective combination with a combination index of 0.28. The same combination caused larger accumulation of cells in the G ₂/M phase of the cell cycle, potent mitochondrial membrane potential loss, and synergistic augmentation of apoptosis. We have shown that synergistic activity might be due to stronger microtubule depolymerization by simultaneous binding of TF and EGCG at different sites on tubulin: TF binds at vinblastine binding site on tubulin, and EGCG binds near colchicines binding site on tubulin. A detailed mechanistic analysis revealed that stronger microtubule depolymerization caused effective downregulation of PI3K/Akt signaling and potently induced mitochondrial apoptotic signals, which ultimately resulted in the apoptotic death of HeLa cells in a synergistic manner.     

Effect of epigallocatechin-3-gallate on iron overload in mice with alcoholic liver disease

Iron has long been related to the pathological process of alcoholic liver disease (ALD). Liver iron overload is known to accelerate the development of ALD. In the present study we aimed to examine the effect of epigallocatechin-3-gallate (EGCG) on iron overload of ALD and to explore the potential mechanisms involved in its protection against ALD in mice. Male C57BL/6J mice were given alcohol by intragastric administration for 12 weeks. At the end of 8th week, ALD mice were treated for 4 weeks for 10, 20 and 30 mg kg^–1 EGCG by intraperitoneal injection. Liver injuries were assessed by histopathologic examination and Serum Alanine Aminotransferase (ALT) levels. Serum iron content, hepatic iron concentration and liver malondialdehyde (MDA) contents were examined. In addition, hepcidin mRNA levels and transferrin (Tf) and transferrin receptor 1 (TfR1) protein levels of liver tissue were also evaluated. Compared with model group, treatment of ALD mice with EGCG ameliorated liver injuries, decreased serum iron level, hepatic iron levels and liver MDA contents, increased hepcidin mRNA level and decreased Tf and TfR1 protein expression in the liver. The results of our study explain a new point of view that the protective effect of EGCG on ALD is associated with its iron-chelating property. The possible mechanisms are that EGCG affects hepatic iron uptake and inhibits iron absorption in the small intestinal.     

Proinflammatory effect of cholesterol and its oxidation products on CaCo-2 human enterocyte-like cells: effective protection by epigallocatechin-3-gallate

Cholesterol and its oxidation products, namely oxysterols, have very recently been shown to potentially interfere with homeostasis of the human digestive tract, by promoting and sustaining irreversible damage of the colonic epithelial layer. This report concerns the strong proinflammatory action that a dietary oxysterol mixture and, to a lesser extent, an identical concentration of unoxidized cholesterol exert on CaCo-2 colonic epithelial cells by up-regulating both expression and synthesis of interleukin 8. The oxysterol mixture and its most effective component, 7β-hydroxycholesterol, are also shown to markedly enhance the expression of key inflammatory and chemotactic cytokines in colonic epithelial cells, more efficiently than unoxidized cholesterol. The sterols' proinflammatory effect seems to be mediated by enhanced activation of NOX1, because it is prevented by pretreatment of the cells with DPI, a selective inhibitor of this oxidase. Importantly, NOX1 hyperactivation by the oxysterol mixture or cholesterol was fully prevented by CaCo-2 cell preincubation with epigallocatechin-3-gallate. Consistently, supplementation with this compound fully protected colonic epithelial cells against overexpression of inflammatory and chemotactic genes induced by the sterols investigated.     

Neuroprotective effect of combination therapy of glatiramer acetate and epigallocatechin-3-gallate in neuroinflammation

Multiple sclerosis (MS) is an inflammatory autoimmune disease of the central nervous system. However, studies of MS and the animal model, experimental autoimmune encephalomyelitis (EAE), indicate that neuronal pathology is the principle cause of clinical disability. Thus, there is need to develop new therapeutic strategies that not only address immunomodulation but also neuroprotection. Here we show that the combination therapy of Glatiramer acetate (GA), an immunomodulatory MS therapeutic, and the neuroprotectant epigallocatechin-3-gallate (EGCG), the main phenol in green tea, have synergistic protective effects in vitro and in the EAE model. EGCG and GA together led to increased protection from glutamate- and TRAIL-induced neuronal cell death in vitro. EGCG combined with GA induced regeneration of hippocampal axons in an outgrowth assay. The combined application of EGCG and GA did not result in unexpected adverse events in vivo. Neuroprotective and neuroregenerative effects could be translated in the in vivo model, where combination treatment with EGCG and GA significantly delayed disease onset, strongly reduced clinical severity, even after onset of symptoms and reduced inflammatory infiltrates. These results illustrate the promise of combining neuroprotective and anti-inflammatory treatments and strengthen the prospects of EGCG as an adjunct therapy for neuroinflammatory and neurodegenerative diseases.     

The green tea polyphenol, epigallocatechin-3-gallate inhibits telomerase and induces apoptosis in drug-resistant lung cancer cells

Epidemiological studies on humans and investigations in animal models suggest that consumption of green tea has anti-cancer effects. Small-cell lung carcinoma (SCLC) has a poor prognosis, particularly due to the development of drug resistance. We investigated the effects of the green tea polyphenol, epigallocatechin-3-gallate (EGCG) on human SCLC cells. EGCG had similar effects (IC(50) of approximately 70 microM) on drug-sensitive (H69) and drug-resistant (H69VP) SCLC cells, indicating that it is not part of the drug resistance phenotype expressed in these cells. In both cell lines, incubation in EGCG at 1 x IC(50) for 24h resulted in 50-60% reduced telomerase activity as measured by a PCR-based assay for telomeric repeats. Colorimetric assays of cells treated for 36 h with EGCG demonstrated a reduction in activities of caspases 3 (50%) and 9 (70%) but not caspase 8, indicating initiation of apoptosis. DNA fragmentation as measured by ELISA occurred within cells treated with EGCG and this was confirmed by TUNEL staining. Flow cytometric analysis of SCLC cells incubated for 36 h in EGCG indicated a cell-cycle block in S phase. These data indicate the potential use of EGCG, and possibly green tea, in treating SCLC.     

Neuroprotective potential of epigallo catechin-3-gallate in PC-12 cells

Oxidative stress is a major player in aging and neurodegenerative disorders. Macromolecular damage occurs as a result of oxidative stress that affects the mitochondria. Mitochondrial damage leads to cell death by apoptosis or necrosis. EGCG is a tea polyphenol that protects the cells against oxidative stress. Neuroprotective potential of EGCG was tested against H₂O₂ induced oxidative stress in PC-12 cells. PC-12 cells were grown in tissue culture flasks. Oxidative stress was induced by adding H₂O₂ to the cells. EGCG was also added and the cell death was assessed using MTT assay. Oxidative stress was assessed by protein carbonyl and thiol status. Mitochondrial membrane potential was studied using JC-1 staining. TNF-α levels were assessed using ELISA. H₂O₂ increased the protein carbonyl content and reduced the thiol status in the PC-12 cells. Cell death was increased in H₂O₂ treated cells as shown by MTT assay. Mitochondrial membrane potential was also decreased along with increase in TNF-α level in H₂O₂ treated cells. EGCG brought about an increase in the cellular thiol status and decreased the protein carbonyl content in the PC-12 cells. Cell death was attenuated by EGCG treatment along with an increase in mitochondrial membrane potential and decrease in TNF-α level. EGCG conferred its antioxidant potential to PC-12 cells as evident by decreased protein damage. Mitochondrial membrane potential was improved along with a decrement in the cell death in PC-12 cells. EGCG acts as a good neutraceutical antioxidant to render neuroprotectivity to PC-12 cells.     

Evaluation of anticancer effects of Juniperus communis extract on hepatocellular carcinoma cells in vitro and in vivo

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and accounts for the fourth leading cause of all cancer deaths. Scientific evidence has found that plant extracts seem to be a reliable choice due to their multitarget effects against HCC. Juniperus communis has been used for centuries in traditional medicine and its anticancer properties have been reported. As a result, the purpose of the study was to investigate the anticancer effect and mechanism of J. communis extract (JCo extract) on HCC in vitro and in vivo. In the present study, we found that JCo extract inhibited the growth of human HCC cells by inducing cell cycle arrest at the G₀/G₁ phase, extensive apoptosis and suppressing metastatic protein expressions in HCC cells. Moreover, the combinational treatment of JCo and VP-16 was found to enhance the anticancer effect, revealing that JCo extract might have the potential to be utilized as an adjuvant to promote HCC treatment. Furthermore, in vivo study, JCo extract significantly suppressed HCC tumor growth and extended the lifespan with no or low systemic and pathological toxicity. JCo extract significantly up-regulated the expression of pro-apoptotic proteins and tumor suppressor p53, suppressed VEGF/VEGFR autocrine signaling, down-regulated cell cycle regulatory proteins and MMP2/MMP9 proteins. Overall, our results provide a basis for exploiting JCo extract as a potential anticancer agent against HCC.     

Epigallocatechin-3-gallate对原代大鼠脂肪细胞脂肪分解及HSL、TGH转录表达的影响

体内能量代谢是维持机体正常生理活动的基础,而脂肪细胞的脂解是能量代谢的核心反应之一,调控脂肪酸从TG库释放,后由血清白蛋白转运至体内各个组织以满足能量需要。如果脂解作用出现障碍,就会影响机体能量的平衡进而引发肥胖和胰岛素抵抗等疾病。表没食子儿茶素没食子酸酯(Epig     

Physiological effects of epigallocatechin-3-gallate (EGCG) on energy expenditure for prospective fat oxidation in humans: A systematic review and meta-analysis

Green tea catechins (GTCs) are known to improve fat oxidation (FOX) during fasted, rested and exercise conditions wherein epigallocatechin-3-gallate (EGCG) is thought to be the most pharmacologically active and has been studied extensively. From the available data of randomized controlled trials (RCTs) on EGCG, we carried out a systematic review and meta-analysis to elucidate whether EGCG consumption indeed increase energy expenditure (EE) and promote FOX. A systematic review of the literature was conducted using electronic databases (PubMed, Embase, Cochrane Library, CINAHL, JICST, JSTPLUS, and JMEDPLUS and others) and eight RCTs were included. RCTs were reviewed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and methodological quality was assessed. After data extraction, results were aggregated using fixed- and random-effect approaches and expressed to quantify the relationship between the dose of EGCG for respiratory quotient (RQ), EE and rate of FOX to compare the EGCG and placebo treatments. The meta-analysis results of verities of studies in terms of dose and length of duration revealed that EGCG supplementation provided significant mean difference (MD) when compared with placebo for RQ [MD: −0.02; 95% confidence intervals (95% CI), −0.04 to 0.00; I²=67%; P=.01] and EE [MD: 158.05 kJ/day; 95% CI, 4.72 to 311.38; I²=0%; P=.04] in fixed-effect approach. Changes in FOX did not reach the level of statistical significance. Meta-analyses of EGCG influence on the body mass index, waist circumference and total body fat mass (TBFM) were also examined and their impact on the promotion of FOX is reported. Effect of EGCG doses was also systematically reviewed. Finding showed that EGCG intake moderately accelerates EE and reduces RQ. The analyses revealed that the EGCG resulted in difference in RQ and EE but the effect on the other measures of energy metabolism was relatively mild. Possibly, EGCG alone has the potential to increase metabolic rate at 300 mg dose. Collectively, the outcome supports the findings that EGCG has an effect on metabolic parameters. However, the large prospective trials are needed to confirm the findings.     

Cisplatin and farnesol co-encapsulated PLGA nano-particles demonstrate enhanced anti-cancer potential against hepatocellular carcinoma cells in vitro

Molecular Biology Reports - Cisplatin (CDDP) is a potent chemotherapeutic drug, but its severe side-effects often prohibit its use. Combined treatment with CDDP plus Farnesol (FAR) and their...     

Dual effects of sodium butyrate on hepatocellular carcinoma cells

Sodium butyrate (NaBu), a histone deacetylase inhibitor, has been shown to inhibit cell growth, induce cell differentiation and apoptosis in multiple cell lines. In present study, we revealed the dual effects of NaBu in regulating hepatocellular carcinoma (HCC) cells. In two different HCC cell lines, SK-Hep1 and SMMC-7721, low concentrations of NaBu induced a significant increase in cell growth ratio and S-phase cell percentage, accompanied by a reduced p21 Cip1 expression at both mRNA and protein levels, while dissimilarly, high concentrations of NaBu inhibited cell growth and induced G1 arrest through up-regulation of p21 Cip1 and p27 Kip1 protein expression. The reduction of p45 Skp2 expression further indicated that the ubiquitin-mediated protein degradation might play a role in NaBu-induced up-regulation of p21 Cip1 and p27 Kip1. Moreover, the high concentration of NaBu was also able to trigger HCC cell apoptosis. Taken together, these results demonstrate the distinct effects of NaBu at different dosages. This finding may contribute to develop more effective tumor therapeutic protocols of NaBu in HCC.