Green tea polyphenol epigallocatechin-3-gallate (EGCG) as adjuvant in cancer therapy

The green tea catechin epigallocatechin gallate induces cell cycle arrest and shows potential synergism with cisplatin in biliary tract cancer cells

Background

The green tea catechin epigallocatechin gallate (EGCG) was shown to effectively inhibit tumor growth in various types of cancer including biliary tract cancer (BTC). For most BTC patients only palliative therapy is possible, leading to a median survival of about one year. Chemoresistance is a major problem that contributes to the high mortality rates of BTC. The aim of this study was to investigate the cytotoxic effect of EGCG alone or in combination with cisplatin on eight BTC cell lines and to investigate the cellular anti-cancer mechanisms of EGCG.

Methods

The effect of EGCG treatment alone or in combination with the standard chemotherapeutic cisplatin on cell viability was analyzed in eight BTC cell lines. Additionally, we analyzed the effects of EGCG on caspase activity, cell cycle distribution and gene expression in the BTC cell line TFK-1.

Results

EGCG significantly reduced cell viability in all eight BTC cell lines (p < 0.05 or p < 0.01, respectively, for most cell lines and EGCG concentrations > 5 μM). Combined EGCG and cisplatin treatment showed a synergistic cytotoxic effect in five cell lines and an antagonistic effect in two cell lines. Furthermore, EGCG reduced the mRNA levels of various cell cycle-related genes, while increasing the expression of the cell cycle inhibitor p21 and the apoptosis-related death receptor 5 (p < 0.05). This observation was accompanied by an increase in caspase activity and cells in the sub-G1 phase of the cell cycle, indicating induction of apoptosis. EGCG also induced a down-regulation of expression of stem cell-related genes and genes that are associated with an aggressive clinical character of the tumor, such as cd133 and abcg2.

Conclusions

EGCG shows various anti-cancer effects in BTC cell lines and might therefore be a potential anticancer drug for future studies in BTC. Additionally, EGCG displays a synergistic cytotoxic effect with cisplatin in most tested BTC cell lines.

Graphical abstract

The combined use of Camellia sinensis and metronomic zoledronate in 4T1 mouse carcinoma against tumor growth and metastasis

In previous studies, we demonstrated that the green tea Camellia sinensis (CS) water extract had potent antitumor and antimetastatic effects on 4T1 breast cancer. The metronomic regimen (0.0125 mg/kg twice a week for 4 weeks) of zoledronate (ZOL) was found to be effective in decreasing tumor burden and metastasis as compared with conventional regimen. The aim of the present study was to investigate the antitumor, antimetastatic and anti-osteolytic effects of the combined use of CS water extract and metronomic ZOL against 4T1 breast carcinoma in vitro and in vivo. The results demonstrated that the combination of CS+ZOL exerted a more potent effect on lung and liver by decreasing tumor burden and metastasis, when compared to CS or metronomic ZOL as monotherapies. The combination of CS+ZOL demonstrated optimal bone protection against breast cancer-induced osteolysis for the three groups of CS, ZOL and CS+ZOL. The in vitro results further demonstrated that ZOL enhanced CS-induced apoptosis in 4T1 cells as assessed by the Annexin V-FITC/PI staining and caspase-3 activity assays. In addition, the combined use of CS+ZOL significantly inhibited 4T1 cell migration. Mechanistic studies showed that the enzyme levels of matrix metalloproteinases (MMP)-2 and MMP-9 were suppressed significantly by CS+ZOL. In conclusion, to the best of our knowledge, this is the first study to investigate the novel combined application of herbal extract CS and chemotherapy ZOL in 4T1 breast cancer. The combination of CS plus metronomic ZOL demonstrated significant antitumor, antimetastatic and anti-osteolytic effects against breast cancer, and suggested potential clinical application for breast cancer patients.

EGCG Enhances Cisplatin Sensitivity by Regulating Expression of the Copper and Cisplatin Influx Transporter CTR1 in Ovary Cancer

Cisplatin is one of the first-line platinum-based chemotherapeutic agents for treatment of many types of cancer, including ovary cancer. CTR1 (copper transporter 1), a transmembrane solute carrier transporter, has previously been shown to increase the cellular uptake and sensitivity of cisplatin. It is hypothesized that increased CTR1 expression would enhance the sensitivity of cancer cells to cisplatin (cDDP). The present study demonstrates for the first time that (-)-epigallocatechin-3-gallate (EGCG), a major polyphenol from green tea, can enhance CTR1 mRNA and protein expression in ovarian cancer cells and xenograft mice. EGCG inhibits the rapid degradation of CTR1 induced by cDDP. The combination of EGCG and cDDP increases the accumulation of cDDP and DNA-Pt adducts, and subsequently enhances the sensitivity of ovarian cancer SKOV3 and OVCAR3 cells to the chemotherapeutic agent. In the OVCAR3 ovarian cancer xenograft nude mice model, the combination of the lower concentration of cDDP and EGCG strongly repressed the tumor growth and exhibited protective effect on the nephrotoxicity induced by cisplatin. Overall, these findings uncover a novel chemotherapy mechanism of EGCG as an adjuvant for the treatment of ovarian cancer.

Mitochondrial modulation by Epigallocatechin 3-Gallate ameliorates cisplatin induced renal injury through decreasing oxidative/nitrative stress, inflammation and NF-kB in mice

Cancer chemotherapy drug cisplatin is known for its nephrotoxicity. The aim of this study is to investigate whether Epigallocatechin 3-Gallate (EGCG) can reduce cisplatin mediated side effect in kidney and to understand its mechanism of protection against tissue injury. We used a well-established 3-day cisplatin induced nephrotoxicity mice model where EGCG were administered. EGCG is a major active compound in Green Tea and have strong anti-oxidant and anti-inflammatory properties. EGCG protected against cisplatin induced renal dysfunction as measured by serum creatinine and blood urea nitrogen (BUN). EGCG improved cisplatin induced kidney structural damages such as tubular dilatation, cast formation, granulovaculoar degeneration and tubular cell necrosis as evident by PAS staining. Cisplatin induced kidney specific mitochondrial oxidative stress, impaired activities of mitochondrial electron transport chain enzyme complexes, impaired anti-oxidant defense enzyme activities such as glutathione peroxidase (GPX) and manganese superoxide dismutase (MnSOD) in mitochondria, inflammation (tumor necrosis factor α and interleukin 1β), increased accumulation of NF-κB in nuclear fraction, p53 induction, and apoptotic cell death (caspase 3 activity and DNA fragmentation). Treatment of mice with EGCG markedly attenuated cisplatin induced mitochondrial oxidative/nitrative stress, mitochondrial damages to electron transport chain activities and antioxidant defense enzyme activities in mitochondria. These mitochondrial modulations by EGCG led to protection mechanism against cisplatin induced inflammation and apoptotic cell death in mice kidney. As a result, EGCG improved renal function in cisplatin mediated kidney damage. In addition to that, EGCG attenuated cisplatin induced apoptotic cell death and mitochondrial reactive oxygen species (ROS) generation in human kidney tubular cell line HK-2. Thus, our data suggest that EGCG may represent new promising adjunct candidate for cisplatin.

Epigallocatechin-3-Gallate Attenuates Oxidative Stress and Inflammation in Obstructive Nephropathy via NF-κB and Nrf2/HO-1 Signalling Pathway Regulation

Oxidative stress and inflammation contribute importantly to the pathogenesis of chronic kidney disease (CKD). Epigallocatechin-3-gallate (EGCG), which is the most abundant and most active catechin polyphenol extracted from green tea, has been proved to have many bioactivities. In this study, the renoprotective effect of EGCG was evaluated in a widely used kidney disease model, the unilateral ureteral obstruction (UUO) mice model. After 14 days of EGCG administration, mean arterial blood pressure, body-weight and obstructed kidney weight were measured. Levels of blood urea nitrogen (BUN) and creatinine (CR) and activities of glutamic-pyruvic transaminase (GPT) and lactate dehydrogenase (LDH) in serum were estimated as indicators of renal function. Periodic acid-Schiff (PAS) staining was performed to observe the pathological changes of the obstructed kidney. Antioxidant enzymes and pro-inflammatory cytokine production were estimated to reflect the oxidative stress and inflammatory state in the obstructed kidney. Finally, the main proteins in the NF-κB and Nrf2 signalling pathway and DNA binding activity of NF-κB and Nrf2 were measured to investigate the effect of EGCG on these two pathways. The results demonstrated that EGCG could restore UUO-induced kidney weight loss and renal dysfunction. In addition, UUO-induced oxidative stress and inflammatory responses in the obstructed kidney were also prevented by EGCG. Furthermore, EGCG could induce both NF-κB and Nrf2 nuclear translocation in the UUO kidney and promote heme oxygenase-1 (HO-1) production. These results indicated that the renoprotective effect of EGCG might be through its NF-κB and Nrf2 signalling pathway regulations.

Gallic acid: a versatile antioxidant with promising therapeutic and industrial applications

Oxidative stress, a result of an overproduction and accumulation of free radicals, is the leading cause of several degenerative diseases such as cancer, atherosclerosis, cardiovascular diseases, ageing and inflammatory diseases.

Molecular mechanism of epigallocatechin-3-gallate in human esophageal squamous cell carcinoma in vitro and in vivo

Epigallocatechin-3-gallate (EGCG), the major polyphenol of green tea, has been shown to inhibit proliferation in various types of tumors. However, few studies concerning the role and mechanism of EGCG in esophageal squamous cell carcinoma are available. Therefore, the antitumor mechanism of EGCG needs to be investigated. The present study aimed to examine the antitumor effect of EGCG on the human esophageal squamous cell carcinoma cell lines, Eca-109 and Te-1, in vitro and in vivo. Cell viability was assessed using the MTT assay and tumor formation and growth in murine xenograft models with or without EGCG treatment. Cell cycle analysis and levels of reactive oxygen species (ROS) were detected using flow cytometry. Apoptosis was measured by Annexin/propidium iodide staining. Caspase-3 cleavage and vascular endothelial growth factor (VEGF) expression were detected using western blot analysis and immunohistochemistry in tumor cell lines and tumor xenografts, respectively. The results showed that EGCG inhibited proliferation in the Eca-109 and Te-1 cells in a time- and dose-dependent manner. Tumor cells were arrested in the G1 phase and apoptosis was accompanied by ROS production and caspase-3 cleavage. In a mouse model, EGCG significantly inhibited the growth of Eca-109 tumors by increasing the expression of cleaved-caspase-3 and decreasing VEGF protein levels. Taken together, the results suggest that EGCG inhibits proliferation and induces apoptosis through ROS production, caspase-3 activation, and a decrease in VEGF expression in vitro and in vivo. Furthermore, EGCG may have future clinical applications for novel approaches to treat esophageal squamous cell carcinoma.

The effect of (-)-epigallocatechin 3-O--gallate in vitro and in vivo in Leishmania braziliensis: involvement of reactive oxygen species as a mechanism of action

BACKGROUND

Leishmaniasis is a parasitic disease associated with extensive mortality and morbidity. The treatment for leishmaniasis is currently based on pentavalent antimonials and amphotericin B; however, these drugs result in numerous adverse side effects. Natural compounds have been used as novel treatments for parasitic diseases. In this paper, we evaluated the effect of (-)-epigallocatechin 3-O-gallate (EGCG) on Leishmania braziliensis in vitro and in vivo and described the mechanism of EGCG action against L. braziliensis promastigotes and intracellular amastigotes.

METHODOLOGY/PRINCIPAL FINDING

In vitro activity and reactive oxygen species (ROS) measurements were determined during the promastigote and intracellular amastigote life stages. The effect of EGCG on mitochondrial membrane potential (ΔΨm) was assayed using JC-1, and intracellular ATP concentrations were measured using a luciferin-luciferase system. The in vivo experiments were performed in infected BALB/c mice orally treated with EGCG. EGCG reduced promastigote viability and the infection index in a time- and dose-dependent manner, with IC50 values of 278.8 µM and 3.4 µM, respectively, at 72 h and a selectivity index of 149.5. In addition, EGCG induced ROS production in the promastigote and intracellular amastigote, and the effects were reversed by polyethylene glycol (PEG)-catalase. Additionally, EGCG reduced ΔΨm, thereby decreasing intracellular ATP concentrations in promastigotes. Furthermore, EGCG treatment was also effective in vivo, demonstrating oral bioavailability and reduced parasitic loads without altering serological toxicity markers.

CONCLUSIONS/SIGNIFICANCE

In conclusion, our study demonstrates the leishmanicidal effects of EGCG against the two forms of L. braziliensis, the promastigote and amastigote. In addition, EGCG promotes ROS production as a part of its mechanism of action, resulting in decreased ΔΨm and reduced intracellular ATP concentrations. These actions ultimately culminate in parasite death. Furthermore, our data suggest that EGCG is orally effective in the treatment of L. braziliensis-infected BALB/c mice without altering serological toxicity markers.

Glutamate as chemotactic fuel for diffuse glioma cells: are they glutamate suckers?

Diffuse gliomas comprise a group of primary brain tumors that originate from glial (precursor) cells and present as a variety of malignancy grades which have in common that they grow by diffuse infiltration. This phenotype complicates treatment enormously as it precludes curative surgery and radiotherapy. Furthermore, diffusely infiltrating glioma cells often hide behind a functional blood-brain barrier, hampering delivery of systemically administered therapeutic and diagnostic compounds to the tumor cells. The present review addresses the biological mechanisms that underlie the diffuse infiltrative phenotype, knowledge of which may improve treatment strategies for this disastrous tumor type. The invasive phenotype is specific for glioma: most other brain tumor types, both primary and metastatic, grow as delineated lesions. Differences between the genetic make-up of glioma and that of other tumor types may therefore help to unravel molecular pathways, involved in diffuse infiltrative growth. One such difference concerns mutations in the NADP(+)-dependent isocitrate dehydrogenase (IDH1 and IDH2) genes, which occur in >80% of cases of low grade glioma and secondary glioblastoma. In this review we present a novel hypothesis which links IDH1 and IDH2 mutations to glutamate metabolism, possibly explaining the specific biological behavior of diffuse glioma.

Protective effect of (-)-epigallocatechin-3-gallate on capsaicin-induced DNA damage and oxidative stress in human erythrocyes and leucocytes in vitro

The aim of this study is to show that protective effects of the main catechin (-)-epigallocatechin-3-gallate (EGCG) against capsaicin (CAP) induced oxidative stress and DNA damage in human blood in vitro. Superoxide dismutase, catalase, glutathione peroxidase and malondialdehyde (MDA) level were studied in erythrocytes and leucocytes with increased concentrations of CAP. DNA damage in leucocytes was measured by the comet assay. Human blood cells have been administered with doses between 0 and 200 μM of CAP and/or EGCG (20 μM) for an hour at 37 °C. Treatment with CAP alone has increased the levels of MDA and decreased antioxidant enzymes in human blood cells. A significant increase in tail DNA%, mean tail length and tail moment indicating DNA damage has been observed at the highest dose of CAP treatment when compared to controls. Treatment of cells with CAP plus EGCG prevented CAP-induced changes in antioxidant enzyme activities and MDA level and mean tail lenght indicating DNA damage. A significant increase in mean tail lenght was observed at high doses of CAP. These data suggest that EGCG can prevent toxicity to human erythrocytes and leucocytes caused by CAP, only at low doses.

EGCG enhances the efficacy of cisplatin by downregulating hsa-miR-98-5p in NSCLC A549 cells

In the current study, the enhanced efficacy of cisplatin caused by (-)-epigallocatechin-3-gallate (EGCG) in nonsmall cell lung cancer (NSCLC) A549 cells was observed. The tumor size was significantly smaller in vivo in the combination of cisplatin and EGCG group, as compared with cisplatin-only group. However, in NCI-H460 cells, another kind of NSCLC cells, the efficacy of cisplatin was antagonized by EGCG. MiRNA microarray showed that hsa-miR-98-5p and hsa-miR-125a-3p were differentially expressed after EGCG treatment in these 2 cell lines. After transfection of hsa-miR-98-5p inhibitor, the survival fraction of both A549 and NCI-H460 cells was decreased upon cisplatin treatment. Meanwhile, as a critical regulator in the cisplatin-induced apoptosis, p53 was elevated by silencing of hsa-miR-98-5p. These results suggested that EGCG inhibited the expression of hsa-miR-98-5p, followed by an increase of p53, thus the efficacy of cisplatin was enhanced. Bioinformatics analysis showed that hsa-miR-125a-3p might have a strong connection with classical MAPK pathway. Taken together, these findings indicate that hsa-miR-98-5p could be a potential target in clinical cisplatin treatment of NSCLC. The combination of EGCG and cisplatin might be an effective therapeutic strategy in treating some type of NSCLC, although the possibility of antagonistic interactions must also be taken into account.

A new antioxidant beverage produced with green tea and apple

Green tea and apple are natural products with health benefits. These healthy properties are linked closely to the antioxidant compounds, mainly phenolic compounds. These antioxidant compounds have a potential for preventing and treating cancer, cardiovascular, inflammatory and neurodegenerative diseases in humans. The aim of the present work was to design a new beverage with high antioxidant power combining extracts of green tea and apple, studying the antioxidant composition and activity, organoleptic properties (colour) and stability status during storage at different temperatures. The majority compounds identified in the beverage were flavan-3-ols, being the (-)-epigallocatechin-3-gallate which had the highest concentration. After storage, floridzine was the compound with lower decrease of concentration. The new designed beverage had a good colour, and high antioxidant activity and stability at room temperature, so that the beverage needs no refrigeration, showing potential for the development of new healthy functional beverages.

Effects of physiological levels of the green tea extract epigallocatechin-3-gallate on breast cancer cells

Physiological concentrations of the green tea extract epigallocatechin-3-gallate (EGCG) caused growth inhibition in estrogen receptor α (ERα)-positive MCF7 cells that was associated with down-regulation of the ERα and reduced insulin-like growth factor binding protein-2 abundance and increased protein abundance of the tumor suppressor genes p53/p21. In contrast to MCF7 cells that have wt p53, EGCG alone did not change cell proliferation or death significantly in another ERα-positive cell line T47D that possesses mutant p53. EGCG increased ERα protein levels and as a consequence, the cells responded significantly better to an ERα antagonist tamoxifen (TAM) in the presence of EGCG. EGCG significantly increased cell death in an ERα-negative cell line, MDA-MB-231 that also possesses mutant p53. EGCG significantly increased the ERα and insulin-like growth factor-I receptor levels and thereby enhanced the sensitivities of the cells to TAM and a blocking antibody targeting the insulin-like growth factor-1 receptor (αIR3). In contrast to MCF7, T47D and MDA-MB-231 breast cancer cells that exhibited significant changes in key molecules involved in breast growth and survival upon treatment with physiological levels of EGCG, the growth, survival, and levels of these proteins in non-malignant breast epithelial cells, MCF10A cells, were not affected.

Epigallocatechin-3-gallate prevents tumor cell implantation/growth in an experimental rat bladder tumor model

The aim of this study was to determine the efficacy of epigallocatechin-3-gallate (EGCG) (Polyphenon E®) in comparison with mitomycin C (MMC) to prevent tumor cell implantation/growth in an animal model of superficial bladder cancer and search for possible mechanism(s) of action. Female Fisher 344 rats were used to study the effects of EGCG and mitomycin C for the prevention of transitional cell tumor implantation (AY-27). Twenty rats served as a control, tumor implantation and saline wash only. Sixty rats were treated with EGCG (100, 200 and 400 µM) intravesically for 60 or 120 min after tumor implantation. Thirty other rats were divided equally and pretreated with 400 µM EGCG or saline for 120 min before tumor initiation. In a separate series of experiments, 30 rats were treated 2 weeks after tumor initiation with saline or EGCG (400 µM). In a different experiment 39 rats were treated with: saline (n=10) EGCG (n=9) 400 µM, MMC (n=10) 0.5 µM, MMC (n=10) 400 µM. Rats were sacrificed 3 weeks following treatment. Gross and histological analyses were performed on the bladders. EGCG and mitomycin C prevented intravesical tumor growth in a concentration- and time-dependent manner. EGCG pretreatment or treatment 2 weeks post tumor implantation did not have therapeutic effects. Molecular modeling suggests that EGCG inhibits urokinase and matrix metalloproteinase-9. EGCG prevents intravesical tumor implantation/growth with a slightly better efficacy than mitomycin C in this experimental model. The data suggest that EGCG lowers proteolytic activity and lowers probability of cancer cell implantation rather than direct cancer cell killing.

In vitro and in vivo effects of (-)-epigallocatechin 3-O-gallate on Leishmania amazonensis

(-)-Epigallocatechin 3-O-gallate (1), the most abundant flavanol in green tea, has been reported to have antiproliferative effects on Trypanosoma cruzi. The present study reports the effects in vitro and in vivo of 1 on Leishmania amazonensis. L. amazonensis-infected macrophages treated with 1 exhibited a significant reduction of the infection index in a dose-dependent manner, with an IC50 value of 1.6 μM. Oral administration of 1 on L. amazonensis-infected BALB/c mice (30 mg/kg/day) resulted in a decrease in the lesion size and parasite burden, without altering serological markers of toxicity. These data demonstrate the in vitro and in vivo leishmanicidal effects of compound 1.