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Metformin, a first-line drug for type 2 diabetes mellitus, has been recognized as a potential anti-tumor agent in recent years. Epigallocatechin-3-gallate (EGCG), as the dominant catechin in green tea, is another promising adjuvant agent for tumor prevention. In the present work, the potential effect of EGCG on the anti-tumor efficacy of metformin in a mouse melanoma cell line (B16F10) was investigated. Results indicated that EGCG and metformin exhibited a synergistic effect on cell viability, migration, and proliferation, as well as signal transducer and activator of transcription 3/nuclear factor-κB (STAT3/NF-κB) pathway signaling and the production of inflammation cytokines. Meanwhile, the combination showed an antagonistic effect on cell apoptosis and oxidative stress levels. The combination of EGCG and metformin also differentially affected the nucleus (synergism) and cytoplasm (antagonism) of B16F10 cells. Our findings provide new insight into the potential effects of EGCG on the anti-tumor efficacy of metformin in melanoma cells.
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Objective • To explore the effect of epigallocatechin-3-gallate (EGCG) on oxidative stress and inflammation in 3T3-L1 adipocytes, and provide a theoretical basis for EGCG to prevent obesity and related chronic diseases. Methods • 3T3-L1 preadipocytes were differentiated to mature adipocytes by in vitro cell culture. The cells were divided into blank control group, and 1, 10 and 50 μg/mL EGCG groups. After 24 hour treatment, intracellular oxidative stress indicators glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA) levels in the cells were measured. The levels of inflammatory indexes interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) were tested by ELISA and realtime PCR, while the expression of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was tested by realtime PCR. Results • Compared with the control group, GSH and SOD levels in 3T3-L1 adipocytes increased in a dose-dependent manner after treatment of EGCG (both P<0.05), while MDA level in 3T3-L1 adipocytes decreased dose-dependently after treatment of EGCG (P<0.05). IL-6, MCP-1 and TNF-α levels in 3T3-L1 adipocytes supernatant declined significantly in a dose-dependent manner after treatment of 1, 10 and 50 μg/mL EGCG (all P<0.05). The expression levels of IL-6, MCP-1 and TNF-α in 3T3-L1 adipocytes were decreased in a dose-dependent manner after 24 h treatment of different concentrations of EGCG. Nrf2 and HO-1 mRNA levels in 3T3-L1 adipocytes increased significantly in a dose-dependent manner after treatment of 10 and 50 μg/mL EGCG (both P<0.05). Conclusion • EGCG plays an antioxidation and anti-inflammatory effects in 3T3-L1 adipocytes, which may be related to up-regulation of Nrf2/HO-1.
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Objective:To evaluate the effect of epigallocatechin-3-gallate (EGCG) and epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG-3Me) on the anti-bacterial effect and the stability of intraradicular dentin-adhesive interface.Methods:EGCG and EGCG3Me with the concentration of 400 μg/ml were incorporated into Single Bond 2 (SB2) respectively to obtain 2 modified adhesives E-SB2 and E3-SB2.Confocal laser scanning microscopy(CLSM) and ultraviolet spectrophotometry were used to evaluate the anti-bacterial effect of the modified adhesives.Micro-Raman spectrum was used to test the degree of conversion (DC) of the adhesives.Push-out bond strength test was conducted to examine the immediate bond strength and the bond strength after themocycling.Results:E-SB2 and E3-SB2 both showed inhibiting effect on the proliferation of E.faecalis,while E3-SB2 performed stronger inhibiting effect.DC and the immediate push-out bond strength of SB2 were not decreased with the incorporation of EGCG or EGCG-3Me(P ＞ 0.05).E-SB2 and E3-SB2 showed significantly higher push-out bond strengths than that of SB2 (P ＜ 0.05) after themocycling.Conclusion:EGCG and EGCG-3Me modified adhesives have anti-bacterial effect and can enhance the stability of bonding between intraradicular dentin and adhesive,EGCG-3Me may have stronger anti-bacterial effect.
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Objective To study the effects of epigallocatechin-3-gallate(EGCG) on noise-induced cochlear injuries.Methods A total of 45 guinea pigs were divided into three groups: the EGCG+noise exposure group, the normal saline+noise exposure group, and the control group.15 Guinea pigs in each group.For EGCG administration, the guinea pigs were given abdominal injection (25 mg/1 000 g) 1 day before and 1 hour before noise exposure (120 dB SPL, 4 h),where for the control group, the guinea pigs received nothing.The hearing function was detected by the auditory brainstem response (ABR) recording after noise exposure immediately, and at 1,3,7, and 14 days after noise exposure.On the 14th day, the cochlea were isolated, and the cells morphology of basal membrane and vascular stria, the outer hair cell movement protein (Prestin), and the 3-nitrotyrosine (3-NT) were examined by immunohistochemistry staminy.Results After noise exposure, ABR thresholds in the EGCG group were higher than that of in the control group(P<0.05), but lower than the normal saline group(P<0.05),though the differences between the other two groups became smaller from day 3.Immunohistochemistry (IHC) staining showed that the three rows of outer hair cells of the control group with Prestin protein stained were arranged neatlyand lack of cell absent, and 3-NT was mainly distributed in the cytoplasm and epidermis.Compared with the normal saline + noise group, after noise exposure, the outer hair cells of EGCG + noise group were in better shape, and prestin staining was clear.Besides, the basal membrane and vascular stria were slightly damaged, the cells arranged neatly and the 3-NT distribution was decreased.Conclusion Preventive intraperitoneal injection of EGCG may reduce cochlea damage caused by noise.
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AIM@#(-)-Epigallocatechin-3-gallate (EGCG), a major compound of tea polyphenols, exhibited antitumor activity in previous studies. In these studies, EGCG usually inhibits EGFR, and impairs the ERK1/2 phosphorylation in tumor cells. The aim was to clarify the mechanism of ERK1/2 activation induced by EGCG.@*METHOD@#Jurkat and 293T cells were treated with EGCG in different culture conditions. Western Blotting (WB) was employed to analyze ERK1/2 and MEK phosphorylation. Cetuximab and FR180204 were used to inhibit cell signaling. The stability of EGCG was assessed by HPLC. The concentration of hydrogen peroxide generated by the auto-oxidation of EGCG was determined by photocolorimetric analysis.@*RESULTS@#Activation of ERK1/2 was observed to be both time-and dose-dependent. Stimulation of cell signaling was dependent on MEK activity, but independent of EGFR activity. Unexpectedly, EGCG was depleted within one hour of incubation under traditional culture conditions. Auto-oxidation of EGCG generated a high level of hydrogen peroxide in the medium. Addition of catalase and SOD to the acidic medium inhibited the oxidation of EGCG. However, this particular condition also prevented the phosphorylation of ERK1/2. The generation of ROS by hydrogen peroxide may also induce ERK1/2 activation in Jurkat cells.@*CONCLUSION@#ERK1/2 phosphorylation was caused by auto-oxidation of EGCG. Traditional culture conditions were determined to be inappropriate for EGCG research.
Subject(s)
Humans , Camellia sinensis , Chemistry , Catalase , Metabolism , Catechin , Pharmacology , Hydrogen Peroxide , Metabolism , Jurkat Cells , MAP Kinase Signaling System , Mitogen-Activated Protein Kinase 3 , Metabolism , Mitogen-Activated Protein Kinase 6 , Metabolism , Oxidation-Reduction , Phosphorylation , Plant Extracts , Pharmacology , Polyphenols , Pharmacology , Superoxide Dismutase , MetabolismABSTRACT
A Dietilnitrosamina (DEN), uma substância reconhecidamente hepatotóxica e carcinogênica, foiutilizada na indução da necrose hepática centrolobular em ratos isogênicos Lewis divididos em 5 grupos de 5 animais. O objetivo deste estudo foi avaliar o efeito quimiopreventivo da epigalocatequina-3-galato (EGCG), de Camellia sinensis (chá verde) no tratamento da hepatotoxicidade celular induzida pela DEN. Foi mensurada a concentração sérica da alanina aminotransferase (ALT) e aspartato aminotransferase(AST) dos diferentes grupos experimentais. No ensaio bioquímico para AST e ALT, houve diferença significativa entre os valores médios do grupo controle (163±70,32) comparado ao grupo DEN (1631±1039,44), sugerindo que a DEN influencia na função hepática. Entretanto, não houve diferença significativa entre o grupo DEN e o tratado com epigalocatequina. A lactato desidrogenase (LDH) éconsiderada um marcador bioquímico comum para avaliação da progressão tumoral, e em relação ao LDH, as amostras não apresentaram diferenças significativas entre o grupo DEN (1385,5±43,13) e DEN + EGCG 150mg ou DEN + EGCG 200mg 1537,5±1010,45). Neste trabalho foi demonstrado que a epigalocatequina nas concentrações de 150 e 200 mg/Kg não induziram alterações hepáticas e também não foi possível verificar nenhuma quimioproteção pela EGCG em animais inicialmente tratados comDEN durante 24 horas. Sendo assim, novos experimentos com diferentes concentrações de EGCG sãonecessários para comprovar seu possível efeito quimioprotetor.
Diethylnitrosamine (DEN), a known hepatotoxic and carcinogenic substance, was used in the induction of centrilobular hepatic necrosis in isogenic Lewis rats divided into 5 groups with 5 animals. The aim of this study was to evaluate the chemopreventive effect of epigallocatechin-3-gallate (EGCG)from Camellia sinensis (green tea) in the treatment of cellular hepatotoxicity induced by DEN. It was measured the serum concentration of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of the different experimental groups. In the biochemistry assay for AST and ALT, there was significant difference between median values of control group (163±70.32) compared to DEN group(1631±1039.44), suggesting that DEN influences on hepatic function. However, there was no significant difference between DEN group to that treated with epigallocatechin. Lactate dehydrogenase (LDH) is considered a common biochemical marker for evaluation of tumor progression, and regarding LDH,the samples presented no significant differences between the DEN group (1385.5±43.13) and DEN + EGCG 150mg or DEN + EGCG 200mg (1537.5± 1010.45). In this work it was demonstrated that epigallocatechin concentrations of 150 and 200 mg/kg did not induce liver alterations and though was not verified any chemoprotective effect by EGCG in animals initially treated with DEN for 24 hours. Moreover, new experiments with different concentrations of EGCG are needed to verify its possiblechemoprotector effect.
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Animals , Rats , Diethylnitrosamine , L-Lactate Dehydrogenase , Rats, Inbred LewABSTRACT
In this study, we investigated the effect of (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea catechins from green tea leaves, on activities of cyclooxygenase (COX)-1 and thromboxane synthase (TXAS), thromboxane A2 (TXA2) production associated microsomal enzymes. EGCG inhibited COX-1 activity to 96.9%, and TXAS activity to 20% in platelet microsomal fraction having cytochrome c reductase (an endoplasmic reticulum marker enzyme) activity and expressing COX-1 (70 kDa) and TXAS (58 kDa) proteins. The inhibitory ratio of COX-1 to TXAS by EGCG was 4.8. These results mean that EGCG has a stronger selectivity in COX-1 inhibition than TXAS inhibition. In special, a nonsteroid anti-inflammatory drug aspirin, a COX-1 inhibitor, inhibited COX-1 activity by 11.3% at the same concentration (50 microM) as EGCG that inhibited COX-1 activity to 96.9% as compared with that of control. This suggests that EGCG has a stronger effect than that of aspirin on inhibition of COX-1 activity. Accordingly, we demonstrate that EGCG might be used as a crucial tool for a strong negative regulator of COX-1/TXA2 signaling pathway to inhibit thrombotic disease-associated platelet aggregation.
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Aspirin , Blood Platelets , Catechin , Cyclooxygenase 1 , Cytochromes c , Endoplasmic Reticulum , Oxidoreductases , Platelet Aggregation , Prostaglandin-Endoperoxide Synthases , Tea , Thromboxane A2ABSTRACT
Inducible nitric oxide synthase (iNOS) is a main enzyme producing nitric oxide during inflammation and thus contributes to the initiation and development of inflammatory cardiovascular diseases such as atherosclerosis. Epigallocatechin-3-gallate (EGCG), the major catechin derived from green tea, has multiple beneficial effects for treating cardiovascular disease, but the effect of EGCG on the expression of vascular iNOS remains unknown. In this study, we investigated (i) whether EGCG inhibits the expression of vascular iNOS induced by angiotensin II in human umbilical vein endothelial cells and, if it does inhibit, (ii) mechanisms underlying the inhibition. Angiotensin II increased expression levels of vascular iNOS; EGCG counteracted this effect. EGCG increased the production of reactive oxygen species. Moreover, EGCG did not affect the production of reactive oxygen species induced by angiotensin II. These data suggest a novel mechanism whereby EGCG provides direct vascular benefits for treating inflammatory cardiovascular diseases.
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Humans , Angiotensin II , Atherosclerosis , Cardiovascular Diseases , Catechin , Human Umbilical Vein Endothelial Cells , Inflammation , Nitric Oxide , Nitric Oxide Synthase Type II , Reactive Oxygen Species , TeaABSTRACT
BACKGROUND AND OBJECTIVES: Aberrant activation of hepatocyte growth factor (HGF) and its receptor, c-Met, has been known to be involved in many human cancer development and progression. During the search for an effective molecule inhibitor of HGF/ c-Met signaling, we have found that Epigallocatechin-3-gallate (EGCG) in green tea might inhibit HGF/c-Met signaling. Studies were performed to address whether EGCG inhibited HGF-dependent tumor proliferation and invasion in HNSCC. MATERIALS AND METHOD: For EGCG inhibition of HGF/c-Met signaling, Western blot was performed. The proliferation of FaDu cells was assayed by counting the number of the cells after treatment by HGF 0, 10 ng/ml, EGCG 1 micrometer, EGCG 10 micrometer, HGF 10+EGCG 1 micrometer, HGF 10+EGCG 10 micrometer. The dispersion of cells was observed by measuring the separation and morphologic changes of the cells after treatment with HGF 0, 10 ng/ml HGF 10+EGCG 1 micrometer, HGF 10+EGCG 10 micrometer for 24 hours. Tumor cell migration was assessed by wound healing assay and tumor cell invasiveness was assessed by the membrane invasion assay. RESULTS: HGF treatment induced rapid activation of c-Met and EGCG inhibited HGF-induced c-Met signaling in FaDu cells. HGF significantly enhanced the growth of HNSCC cells and this phenomenon was inhibited by EGCG in a dose-dependant manner (p<0.05). EGCG inhibited HGF-induced scattering, migration, and invasion of HNSCC cells in a dose-dependent manner (p<0.05). CONCLUSION: Inhibition of HGF/Met by EGCG leads to decreased proliferation, scattering, migration and invasion in vitro, suggesting the possible use of EGCG in HNSCC associated with down-regulation of HGF/Met signaling.
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Humans , Blotting, Western , Catechin , Cell Movement , Down-Regulation , Hepatocyte Growth Factor , Hypopharyngeal Neoplasms , Membranes , Tea , Wound HealingABSTRACT
Matrix metalloproteinases (MMPs) can degrade a wide range of extracellular matrix components. It has been reported that MMP-9 are activated after focal ischemia in experimental animals. (-)-Epigallocatechin-3-gallate (EGCG), a major constituent of green tea polyphenols, is a potent free radical scavenger and reduces the neuronal damage caused by oxygen free radicals. And it has been known that EGCG could reduce the infarction volume in focal brain ischemia and inhibit MMP-9 activity. To delineate the relationship between the anti-ischemic action and the MMP-9-inhibiting action of EGCG, we investigated the effect of EGCG on brain infarction and the activity of matrix metalloproteinase-9 induced by permanent middle cerebral artery occlusion (pMCAO) in ICR mice. EGCG (40 mg/kg, i.p. 15~30 min prior to MCAO) significantly decreased infarction volume at 24 hr after MCAO. GM 6001 (50 mg/kg, i.p. 15~30 min prior to MCAO), a MMP inhibitor, also significantly reduced infarction volume. In zymogram, MMP-9 activities began to increase at ipsilateral cortex at 2 hr after MCAO, and the increments of MMP-9 activities were attenuated by EGCG treatment. Western blot for MMP-9 also showed patterns similar to that of zymogram. These findings demonstrate that the anti-ischemic action of EGCG in mouse focal cerebral ischemia involves its inhibitory effect on MMP-9.
Subject(s)
Animals , Mice , Blotting, Western , Brain Infarction , Brain Ischemia , Brain , Extracellular Matrix , Free Radicals , Infarction , Infarction, Middle Cerebral Artery , Ischemia , Matrix Metalloproteinase 9 , Matrix Metalloproteinases , Mice, Inbred ICR , Middle Cerebral Artery , Neurons , Oxygen , Polyphenols , TeaABSTRACT
PURPOSE: A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), is known to possess anti-cancer properties. In this study, the time-course of the anticancer effects of EGCG on human ovarian cancer cells were investigated to provide insights into the molecular-level understanding of the growth suppression mechanism involved in EGCG-mediated apoptosis and cell cycle arrest. MATERIALS AND METHODS: Three human ovarian cancer cell lines (p53 negative, SKOV-3 cells; mutant type p53, OVCAR-3 cells; and wild type p53, PA-1 cells) were used. The effect of EGCG treatment was studied via a cell count assay, cell cycle analysis, FACS, Western blot and macroarray assay. RESULTS: EGCG exerts a significant role in suppressing ovarian cancer cell growth, showed dose dependent growth inhibitory effects in each cell line and induced apoptosis and cell cycle arrest. The cell cycle was arrested at the G1 phase by EGCG in SKOV-3 and OVCAR-3 cells. In contrast, the cell cycle was arrested in the G1/S phase in PA-1 cells. EGCG differentially regulated the expression of genes and proteins (Bax, p21, Retinoblastoma, cyclin D1, CDK4 and Bcl-XL) more than 2 fold, showing a possible gene regulatory role for EGCG. The continual expression in p21WAF1 suggests that EGCG acts in the same way with p53 proteins to facilitate apoptosis after EGCG treatment. Bax, PCNA and Bcl-X are also important in EGCG-mediated apoptosis. In contrast, CDK4 and Rb are not important in ovarian cancer cell growth inhibition. CONCLUSION: EGCG can inhibit ovarian cancer cell growth through the induction of apoptosis and cell cycle arrest, as well as in the regulation of cell cycle related proteins. Therefore, EGCG-mediated apoptosis could be applied to an advanced strategy in the development of a potential drug against ovarian cancer.
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Humans , Apoptosis , Blotting, Western , Cell Count , Cell Cycle , Cell Cycle Checkpoints , Cell Line , Cyclin D1 , G1 Phase , Ovarian Neoplasms , Proliferating Cell Nuclear Antigen , Retinoblastoma , TeaABSTRACT
OBJECTIVE: A constituent of green tea, (-)-epigallocatechin-3-gallate (EGCG), has been known to possess anti-diabetes, anti-hypertension and anti-cancer properties. In this study, we investigated the anticancer effects of EGCG on human ovarian cancer cell lines. The growth inhibitory mechanism(s) and regulation of cell cycle-related proteins by EGCG were also evaluated. METHODS: To carry out cell counting assay to observe the anti-proliferative effects, we treated 25, 50, and 100 uM EGCG to both ovarian cancer cell lines SKOV-3 and OVCAR-3, respectively. Also, we treated EGCG to PA-1 cells with 6.25, 12.5 and 25 uM, respectively. Six days later, we examined the characteristics of apoptosis and changes in cell cycle regulation by cell counting assay, Annexin V-FITC staining and DNA fragmentation assay, and FACS analysis. In addition, protein and gene expression patterns in SKOV-3 cell were investigated by using cell cycle cDNA chip, RT-PCR, and Western blot analyses. RESULTS: Inhibition of cell growth by cell counts showed in SKOV-3 cells with 48.8%, 82.5%, 99.2% after six days of the treatment with 25, 50, 100 uM of EGCG, respectively. OVCAR-3 cells showed 53.9%, 84.8%, and 97.7% growth inhibition patterns. And PA-1 cells showed 17.1%, 48.4%, and 74.1%, as compared to control. When SKOV-3 cells were tested for EGCG-induced apoptosis, apoptotic cells were observed with 8.6, 11.4, and 23.3-fold at 25, 50, 100 uM EGCG, respectively. And PA-1 cells showed 1.7, 2.4, and 4.2-fold, as compared to control. In contrast, OVCAR-3 did not show EGCG-induced apoptosis. When SKOV-3 cells were tested for their gene expression using cell cycle cDNA chip after treatment with 24.5 uM of EGCG, up-regulations of p21, Bax and cyclin G were shown, while down-regulations of CDK6, E2F-4, and cyclin A were shown. In Western blot assay, up-regulations of Bax and p21 proteins were shown, while down- regulations of cyclin D1, Bcl-XL, Rb, CDK2, E2F-1, E2F-4, PCNA proteins were shown. CONCLUSION: These data support that EGCG can inhibit ovarian cancer cell growth through induction of apoptosis and cell cycle arrest as well as regulation of gene and protein expressions. Thus, EGCG likely provides an additional option for a new and potential drug approach for ovarian cancer.