Green tea catechin, epigallocatechin-3-gallate, inhibits vascular endothelial growth factor angiogenic signaling by disrupting the formation of a receptor complex

A potential mechanism by which green tea may prevent cancer development is through the inhibition of angiogenesis. We have shown previously that the green tea catechin, epigallocatechin gallate (EGCG), inhibits endothelial cell tube formation through the inhibition of vascular endothelial growth factor (VEGF)-induced Akt activation and vascular endothelial (VE)-cadherin phosphorylation. Furthermore, EGCG can suppress oxidant-induced production of the proangiogenic cytokine interleukin (IL)-8. To further elucidate the antiangiogenic mechanisms of EGCG, we investigated its regulation of other molecular processes in VEGF-induced signaling in human umbilical vein endothelial cells (HUVECs). We show that EGCG at physiological doses (0.5-10 microM) markedly inhibits the formation of a vascular endothelial growth factor receptor 2 complex formed upon the binding of its ligand VEGF. This disruption results in a significant and dose-dependent decrease in PI3-kinase activity. Electrophoretic mobility shift assay revealed that EGCG decreased the PI3 kinase-dependent activation and DNA-binding ability of NF-kappaB, likely acting through decreasing phosphorylation and degradation of IkappaB. VEGF-induced IL-8 production at the mRNA (real time RT-PCR) and protein levels (ELISA) are also suppressed with EGCG. These results suggest a novel mechanism for green tea's anticancer effects where EGCG can abrogate VEGF signaling by interfering with the formation of a receptor complex, resulting in attenuated mitogenic and angiogenic signaling.     

Combined effect of green tea and Ganoderma lucidum on invasive behavior of breast cancer cells

Epidemiological studies have suggested that consumption of green tea may decrease the risk of a variety of cancers. In addition, mushroom Ganoderma lucidum has been used for the promotion of health, longevity and treatment of cancer in traditional Chinese medicine. In the present study we show that extract from green tea (GTE) increased the anticancer effect of G. lucidum extract (GLE) on cell proliferation (anchorage-dependent growth) as well as colony formation (anchorage-independent growth) of breast cancer cells. This effect was mediated by the down-regulation of expression of oncogene c-myc in MDA-MB-231 cells. Although individual GTE and GLE independently inhibited adhesion, migration and invasion of MDA-MB-231 cells, their combination demonstrated a synergistic effect, which was mediated by the suppression of secretion of urokinase plasminogen activator (uPA) from breast cancer cells. Our study suggests the potential use of combined green tea and G. lucidum extracts for the suppression of growth and invasiveness of metastatic breast cancers.     

Human chondrosarcoma secretes vascular endothelial growth factor to induce tumor angiogenesis and stores basic fibroblast growth factor for regulation of its own growth.

Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are well-known factors that induce neovascularization in many tumors. The molecular mechanisms that regulate tumor angiogenesis in human chondrosarcoma are not clear. We assessed in this work the angiogenic activities of a human chondrosarcoma cell line (OUMS-27) in vivo and determined the efficacies of angiogenic factors derived from OUMS-27 cells on human umbilical vein endothelial cells (HUVECs) in vitro. Tumor xenografts induced an increase in the formation of neovessels, but the distributions of Ki-67 antigen, VEGF and bFGF were unaffected. We also demonstrated that OUMS-27 cells secreted VEGF(165) into the culture medium and that it was the maximal angiogenic factor to stimulate endothelial proliferation and migration in chondrosarcoma. Anti-VEGF antibodies induced an approximately 70% inhibition of these responses of HUVECs, but did not have any effect on OUMS-27 cells. Anti-bFGF antibodies suppressed not only the activities of HUVECs but also the growth of tumor cells in vitro. We indicate that angiogenesis is principally elicited by VEGF(165) and that tumorigenesis is mainly regulated by bFGF stored in the extracellular matrix of OUMS-27 cells. The present study may offer the availability of combination therapies for inhibition of VEGF and bFGF action on vascular endothelial cells and chondrosarcoma cells, respectively.     

An in vitro tumor model: analysis of angiogenic factor expression after chemotherapy

Tumor tissues include malignant cells and a stroma made up of mainly inflammatory cells, endothelial cells, and fibroblasts. To differentiate the effects of treatment on angiogenic cytokine secretion in tumor tissue, exponential and stationary phase human CaKi-1 renal cell carcinoma cells, human SW2 small cell lung carcinoma cells, human umbilical vein endothelial cells (HUVECs), murine NIH-3T3 fibroblasts, and murine RAW264.7 macrophages were exposed to gemcitabine, paclitaxel, carboplatin, and the protein kinase Cbeta inhibitor LY317615, and secretion (24 h) of tumor necrosis factor-alpha, basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)-beta was determined by a Luminex FlowMetrix assay. After 72 h of exposure, exponential RAW, 3T3, and SW2 cells were sensitive to gemcitabine; exponential and stationary SW2 and HUVECs were sensitive to paclitaxel; and exponential and stationary HUVECs were most sensitive to LY317615. None of the cells secreted detectable tumor necrosis factor-alpha. Generally, exponential cells secreted higher levels of cytokines than stationary cells (stationary cells secreted approximately 10 times less TGF-beta). Only malignant cells secreted VEGF (80-300 pg/10(6) cells). VEGF secretion by exponential SW2 cells decreased in an anticancer agent concentration-dependent manner. Every cell type secreted TGF-beta (40-700 pg/10(6) cells). Exponential 3T3, RAW, CaKi-1, and SW2 cells secreted the most TGF-beta, and levels did not decrease with treatment. Only CaKi-1, SW2, and HUVECs secreted bFGF (0.5-50 pg/10(6) cells). CaKi-1 cells increased secretion of bFGF with therapy. Although malignant cells alone secreted VEGF, stromal cells secreted TGF-beta and bFGF at levels comparable with or greater than malignant cells and thus may be important contributors to tumor growth and progression.     

Green tea polyphenols and its constituent epigallocatechin gallate inhibits proliferation of human breast cancer cells in vitro and in vivo

Tea [Camellia sinensis (Theaceae)] intake is second only to water in terms of worldwide popularity as a beverage. The Green tea polyphenols have been shown to have a protective effect in prostate cancer in various pre-clinical animal models and has been reported to be effective in several other cancer types as well. An inverse association between the risk of breast cancer and the intake of green tea has also been reported in Asian Americans. Several epidemiological studies have shown that breast cancer progression is delayed in the Asian population that consumes green tea on regular basis. In this study, we report the effectiveness of green tea polyphenols (GTP) and its constituent Epigallocatechin Gallate (EGCG) in tumor regression using both in-vitro cell culture models and in vivo athymic nude mice models of breast cancer. The anti-proliferative effect of GTP and EGCG on the growth of human breast cancer MDA-MB-231 cell was studied using a tetrazolium dye-based (MTT) assay. Both GTP and EGCG treatment had the ability to arrest the cell cycle at G1 phase as assessed by flow cytometry. The expression of Cyclin D, Cyclin E, CDK 4, CDK 1 and PCNA were down regulated over the time in GTP and EGCG treated experimental group, compared to the untreated control group as evaluated by western blot analysis for cell cycle proteins, which corroborated the G1 block. Nude mice inoculated with human breast cancer MDA-MB-231 cells and treated with GTP and EGCG were effective in delaying the tumor incidence as well as reducing the tumor burden when compared to the water fed and similarly handled control. GTP and EGCG treatment were also found to induce apoptosis and inhibit the proliferation when the tumor tissue sections were examined by immunohistochemistry. Our results suggest that GTP and EGCG treatment inhibits proliferation and induce apoptosis of MDA-MB-231 cells in-vitro and in-vivo. All together, these data sustain our contention that GTP and EGCG have anti-tumor properties.     

Upregulation of basic fibroblast growth factor in breast carcinoma and its relationship to vascular density, oestrogen receptor, epidermal growth factor receptor and survival

Background: Angiogenesis, the process whereby endothelial cells divide and migrate to form new blood capillaries, has been assessed in tumours by measuring microvessel density. High microvessel density is a significant adverse prognostic factor in breast cancer. The angiogenic factor, basic fibroblast growth factor (bFGF), has been associated with tumourigenesis and metastasis in several human cancers. There are few quantitative studies of bFGF expression in normal tissues compared to cancer.Patients and methods: We have measured bFGF levels in 149 human primary breast carcinomas and assessed the findings in relation to microvessel density, oestrogen receptor (ER) and epidermal growth factor receptor (EGFR).Basic FGF levels were measured by ELISA. Western blotting and immunohistochemistry were carreid out to confirm the presence of bFGF.Results: Levels of bFGF were more than 10-fold higher in tumour cytosols compared to reduction mammoplasty tissue and 3-fold compared to non neoplastic cytosols from the same breast as the tumour (P < 0.0001). Immunohistochemistry showed bFGF protein was localised exclusively in the stroma whereas no bFGF staining was observed in the epithelial cells. High bFGF levels were significantly related to high ER (P = 0.01). Similarly, high bFGF levels were significantly related to low grade (P = 0.046) and to small tumour size (P = 0.04). No significant relationship was observed between bFGF and microvessel count, EGFR or age. In univariate analysis and in a Cox proportional hazard model bFGF did not reach significance for overall or relapse free survival.Conclusions: Our results show that although bFGF is elevated in breast carcinomas compared to normal breast tissue it is not related to microvessel density and it is not an independent predictor of survival in breast cancer patients. Basic FGF may be one of multiple factors that synergise with other growth factors such as VEGF to enhance angiogenesis.     

The green tea catechins, (-)-Epigallocatechin-3-gallate (EGCG) and (-)-Epicatechin-3-gallate (ECG), inhibit HGF/Met signaling in immortalized and tumorigenic breast epithelial cells

The hepatocyte growth factor (HGF) receptor, Met, is a strong prognostic indicator of breast cancer patient outcome and survival, suggesting that therapies targeting Met may have beneficial outcomes in the clinic. (-)-Epigallocatechin-3-gallate (EGCG), a catechin found in green tea, has been recognized as a potential therapeutic agent. We assessed the ability of EGCG to inhibit HGF signaling in the immortalized, nontumorigenic breast cell line, MCF10A, and the invasive breast carcinoma cell line, MDA-MB-231. HGF treatment in both cell lines induced rapid, sustained activation of Met, ERK and AKT. Pretreatment of cells with concentrations of EGCG as low as 0.3 microM inhibited HGF-induced Met phosphorylation and downstream activation of AKT and ERK. Treatment with 5.0 microM EGCG blocked the ability of HGF to induce cell motility and invasion. We assessed the ability of alternative green tea catechins to inhibit HGF-induced signaling and motility. (-)-Epicatechin-3-gallate (ECG) functioned similar to EGCG by completely blocking HGF-induced signaling as low as 0.6 microM and motility at 5 microM in MCF10A cells; whereas, (-)-epicatechin (EC) was unable to inhibit HGF-induced events at any concentration tested. (-)-Epigallocatechin (EGC), however, completely repressed HGF-induced AKT and ERK phosphorylation at concentrations of 10 and 20 microM, but was incapable of blocking Met activation. Despite these observations, EGC did inhibit HGF-induced motility in MCF10A cells at 10 microM. These observations suggest that the R1 galloyl and the R2 hydroxyl groups are important in mediating the green tea catechins' inhibitory effect towards HGF/Met signaling. These combined in vitro studies reveal the possible benefits of green tea polyphenols as cancer therapeutic agents to inhibit Met signaling and potentially block invasive cancer growth.     

Prevention of Mammary Carcinogenesis in C3H/OuJ Mice by Green Tea and Tamoxifen

Background: Tamoxifen (TAM) is useful in the chemoprevention of breast cancer, and green tea catechins,including (-)-epigallocatechin gallate (EGCG), may have similar actions. In this study, we investigated theireffects, alone or in combination, on mammary carcinogenesis using breast cancer cells and preneoplastic lesionsinC3H/OuJ mice. Methods: Growth inhibitory effects of EGCG and TAM on MCF-7 cells were evaluatedwith the anchorage-independent colony forming assay. The effects on mammary tumor carcinogenesis andpreneoplastic lesions were assessed in vivo using animals treated with GTE in drinking water (1%, 0.1%), or atamoxifen pellet (10 mg/ animal, subcutaneously inoculated) or both agents in combination (1%GTE + 10 mgTAM). The number and size of mammary tumors were measured weekly during treatment. At 48 weeks of age,mice were sacrificed for the examination of hyperplastic alveolar nodules (HAN) and argyrophilic nucleolarorganizer regions (AgNOR). Results: In the anchorage-independent growth assay, EGCG and TAM exhibiteddose-dependent antiproliferative effects on MCF-7 cells. In the tumor formation assay, tumor incidences weredecreased in the GTE, TAM, and GTE+TAM groups, particularly in the latter, in which no tumors developed.AgNOR counts were also significantly lower in the 1%GTE+TAM compared with the 1%GTE group, suggestingan additional anticarcinogenic effect. Conclusion: These data suggest that GTE and TAM, individually and incombination, have potential for chemoprevention of breast cancer.     

Epigallocatechin-3-gallate inhibits the PDGF-induced VEGF expression in human vascular smooth muscle cells via blocking PDGF receptor and Erk-1/2

Platelet-derived growth factor (PDGF) has been known to induce vascular endothelial growth factor (VEGF) expression in human vascular smooth muscle cells (hVSMCs). We previously reported that Erk-1/2 and AP-1 pathways are crucial in the PDGF-induced VEGF expression in hVSMCs . In this study, we investigated the effect of epigallocatechin-3-gallate (EGCG), the major green tea catechin, on the PDGF-induced VEGF expression in hVSMCs and the underlying mechanisms. EGCG were found to inhibit dose-dependently the VEGF expression and activation of PDGF receptor, Erk-1/2 and AP-1 induced by PDGF. In addition, cell free studies demonstrated that EGCG could directly inhibit the Erk-1/2 activity. Conditioned media from the hVSMCs treated with PDGF could remarkably stimulate the in vitro growth of human umbilical vein endothelial cells (HUVECs) but the media from the EGCG-pretreated hVSMCs lost its stimulatory activity for HUVEC proliferation. These results suggest that EGCG may exert the anti-angiogenic effect by inhibiting the PDGF-induced VEGF expression at multiple signaling levels.     

Tanshinone I suppresses growth and invasion of human breast cancer cells, MDA-MB-231, through regulation of adhesion molecules

The role of cell adhesion molecules has been studied extensively in the process of inflammation, and these molecules are critical components of carcinogenesis and cancer metastasis. This study investigated the effect of tanshinone I derived from the traditional herbal medicine, Salvia miltiorrhiza Bunge, on the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in tumor necrosis factor-alpha (TNF-alpha)-stimulated endothelial cells. Furthermore, this study investigated the effect of tanshinone I on cancer growth, invasion and angiogenesis on human breast cancer cells MDA-MB-231, both in vitro and in vivo. Tanshinone I dose dependently inhibited ICAM-1 and VCAM-1 expressions in human umbilical vein endothelial cells (HUVECs) that were stimulated with TNF-alpha for 6 h. Pretreatment with tanshinone I significantly reduced adhesion of either monocyte U937 or MDA-MB-231 cells to HUVECs. Interestingly, the inhibitory effect of tanshinone I on monocyte and cancer cell adhesion to HUVECs was mimicked by transfection with ICAM-1 and VCAM-1 small interfering RNA. In addition, tanshinone I effectively inhibited TNF-alpha-induced production of vascular endothelial growth factor (VEGF) and VEGF-mediated tube formation in HUVECs. Tanshinone I also inhibited TNF-alpha-induced VEGF production in MDA-MB-231 cells and migration of MDA-MB-231 cells through extracellular matrix. Additionally, reduction of tumor mass volume and decrease of metastasis incidents by tanshinone I were observed in vivo. In conclusion, this study provides a potential mechanism for the anticancer effect of tanshinone I on breast cancer cells, suggesting that tanshinone I may serve as an effective drug for the treatment of breast cancer.     

Selective and effective killing of angiogenic vascular endothelial cells and cancer cells by targeting tissue factor using a factor VII-targeted photodynamic therapy for breast cancer

The cell surface receptor tissue factor (TF) is regarded as a common but specific target on angiogenic tumor vascular endothelial cells (VECs) and tumor cells in many types of cancer including breast cancer. The purpose of this study is to develop a selective and effective TF-targeting photodynamic therapy (PDT) by using its natural ligand factor VII (fVII)-conjugated Sn(IV) chlorin e6 (SnCe6) for the treatment of breast cancer. A cross linker EDC was used to covalently conjugate fVII protein to SnCe6, and the binding activity and phototoxicity was confirmed by ELISA and in vitro PDT. The efficacy of fVII-tPDT was assessed in vitro by crystal violet staining assay and in vivo by measuring tumor size in mice carrying murine or human breast cancer xenografts. We show that active site-mutated (K341A) fVII protein can be internalized into breast cancer cells and vascular endothelial growth factor (VEGF)-stimulated human umbilical vein endothelial cells (HUVECs) as angiogenic VECs. fVII-tPDT not only enhances 12-fold the in vitro efficacy but also selectively and effectively kills angiogenic HUVECs and breast cancer cells via specifically binding of fVII to TF and inducing apoptosis and necrosis as the underlying mechanism. Furthermore, fVII-tPDT can significantly inhibit the tumor growth of murine and human breast cancer without obvious toxicities in mice. We conclude that fVII-tPDT using fVII–SnCe6 conjugate can selectively and effectively kill angiogenic VECs and breast cancer cells in vitro and significantly inhibit the tumor growth of murine and human breast cancer in mice.     

Trastuzumab-resistant HER2-driven breast cancer cells are sensitive to epigallocatechin-3 gallate

Overexpression of the epidermal growth factor receptor family member HER2 is found in approximately 30% of breast cancers and is a target for immunotherapy. Trastuzumab, a humanized monoclonal antibody against HER2, is cytostatic when added alone and highly successful in clinical settings when used in combination with other chemotherapeutic agents. Unfortunately, HER2 tumors in patients develop resistance to trastuzumab or metastasize to the brain, which is inaccessible to antibody therapy. Previously, we showed that the green tea polyphenol epigallocatechin-3 gallate (EGCG) inhibits growth and transformed phenotype of Her-2/neu-driven mouse mammary tumor cells. The different modes of action of EGCG and trastuzumab led us to hypothesize that EGCG will inhibit HER2-driven breast cancer cells resistant to trastuzumab. We studied trastuzumab-resistant BT474 human breast cancer cells, isolated by chronic trastuzumab exposure, and JIMT-1 breast cancer cells, derived from a pleural effusion in a patient who displayed clinical resistance to trastuzumab therapy. EGCG treatment caused a dose-dependent decrease in growth and cellular ATP production, and apoptosis at high concentrations. Akt activity was suppressed by EGCG leading to the induction of FOXO3a and target cyclin-dependent kinase inhibitor p27Kip1 levels. Thus, EGCG in combination with trastuzumab may provide a novel strategy for treatment of HER2-overexpressing breast cancers, given that EGCG can cross the blood-brain barrier.     

Luteolin抑制血管生成的机制研究

目的:探讨luteolin对血管的抑制机制。方法:采用不同浓度luteolin处理人微血管内皮细胞,观察luteolin对内皮细胞生长,乳腺癌细胞MDA-MB 231培养液介导的内皮细胞趋化抑制作用。并探讨luteolin对内皮细胞中IL-8信号激活的抑制作用,及luteolin对血管生成抑制作用机制。结果:Luteolin对人微血管内皮细胞细胞增殖抑制作用明显(P<0.01)。Luteolin可抑制乳腺癌细胞MDA-MB 231培养液介导的内皮细胞趋化作用(P<0.01),并明显抑制IL-8对内皮细胞ERK及AKT的激活。结论:Luteolin可抑制人微血管内皮细胞增殖及乳腺癌细胞MDA-MB 231培养液介导的趋化作用,并可抑制IL-8对人微血管内皮细胞的信号激活作用,luteolin抗血管生成作用在预防恶性肿瘤复发及转移中可能有重要的作用。     

Serum semicarbazide-sensitive amine oxidase (SSAO) activity correlates with VEGF in non-small-cell lung cancer patients

Semicarbazide-sensitive amine oxidase (SSAO) is an enzyme associated with vascular systems in mammals. SSAO catalyzes the deamination of primary monoamines and has been suggested to be a risk factor in vascular disorders, e.g., diabetic vascular complications. The primary aim of the present study was to investigate if serum SSAO activity is associated with clinical parameters in non-small cell lung cancer (NSCLC) patients. Secondary aims were to investigate if there is a correlation between SSAO activity and the angiogenic factors vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF).Thirty-three patients donated 231 serum samples. Detectable levels of bFGF, VEGF, and SSAO were observed in all patients. Serum SSAO activity was not statistically associated with survival (p = 0.35). A highly significant statistical correlation was found between SSAO activity and VEGF (p < 0.0001). No significant correlation between SSAO and bFGF was observed.We conclude that SSAO was not associated with survival in patients with NSCLC. However, a strong correlation between serum SSAO activity and the angiogenic factor VEGF was found that might implicate new aspects of the mechanisms controlling angiogenesis.     

Modulation of the insulin-like growth factor-I system by N-(4-hydroxyphenyl)-retinamide in human breast cancer cell lines.

The potent mitogenic activity of insulin-like growth factor I (IGF-I) on breast epithelium is inhibited by retinoic acid in oestrogen receptor-positive (ER+) breast cancer cell lines. We studied and compared the effects of N-(4-hydroxyphenyl)-retinamide (4-HPR) in terms of growth inhibition and modulation of the IGF-I system in ER+ (MCF-7) and oestrogen receptor-negative (ER-) (MDA-MB231) breast cancer cell lines. Treatment with 1-10 microM 4-HPR for up to 96 h induced a dose- and time-dependent inhibition of proliferation in both breast cancer cell lines. Induction of apoptosis was much more evident in MCF-7 than in MDA-MB231 cells (30-40% compared with 0-5% respectively at 5 microM for 48 h). Exogenous human recombinant IGF-I (hr-IGF-I)-stimulated cell proliferation was abolished by 1 microM 4-HPR in MCF-7 cells. Immunoreactive IGF-I-like protein concentration in conditioned medium was reduced by 38% in MCF-7 and by 90% in MDA-MB231 cell lines following treatment for 48 h with 5 microM 4-HPR. Western ligand blot analysis showed a reduction of IGF-binding protein 4 (BP4) and BP5 by 67% and 87%, respectively, in MCF-7, whereas IGF-BP4 and -BP1 were reduced by approximately 20% in MDA-MB231 cells. Exposure to 5 microM 4-HPR for 48 h inhibited [125I]IGF-I binding and Scatchard analysis revealed a decrease of more than 50% in maximum binding capacity (Bmax) and a reduced receptor number/cell in both cancer cell lines. Steady-state type I IGF-receptor mRNA levels were reduced by approximately 30% in both tumour cell lines. We conclude that 4-HPR induces a significant down-regulation of the IGF-I system in both ER+ (MCF-7) and ER- (MDA-MB231) breast cancer cell lines. These findings suggest that, in our model, interference with the ER signalling pathway is not the only mechanism of breast cancer growth inhibition by 4-HPR.     

Angiogenesis Markers Quantification in Breast Cancer and Their Correlation with Clinicopathological Prognostic Variables

Tumoural angiogenesis is essential for the growth and spread of breast cancer cells. Therefore the aim of this study was to assess the diagnostic performance of angiogenesis markers in tumours and there reflecting levels in serum of breast cancer patients. Angiogenin, Ang2, fibroblast growth factor basic, intercellular adhesion molecule (ICAM)-1, keratinocyte growth factor (KGF), platelet-derived growth factor-BB, and VEGF-A were measured using a FASTQuant angiogenic growth factor multiplex protein assay. We observed that breast cancer tumours exhibited high levels of PDGF-BB, bFGF and VEGF, and extremely high levels of TIMP-1 and Ang-2, whereas in serum we found significantly higher levels of Ang-2, PDGF-BB, bFGF, ICAM-1 and VEGF in patients with breast cancer compared to the benign breast diseases patients. Moreover, some of these angiogenesis markers evaluated in tumour and serum of breast cancer patients exhibited association with standard clinical parameters, ER status as well as MVD of tumours. Angiogenesis markers play important roles in tumour growth, invasion and metastasis. Our results suggest that analysis of angiogenesis markers in tumour and serum of breast cancer patients using multiplex protein assay can improve diagnosis and prognosis in this diseases.     

Epigallocatechin-3-gallate decreases VEGF production in head and neck and breast carcinoma cells by inhibiting EGFR-related pathways of signal transduction

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

Prognostic correlation of basic fibroblast growth factor and vascular endothelial growth factor in 1307 primary breast cancers

This study was designed to investigate the possible relationship between the protein expression of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) with p53 status, breast cancer prognostic factors, metastatic site, and survival after adjuvant therapy. Basic fibroblast growth factor and VEGF expression were determined by enzyme-linked immunosorbent assays in cytosol specimens obtained from 1307 patients with T1-3 primary breast cancer (789 node-negative, 518 node-positive) diagnosed between 1990 and 1997. The median follow-up time was 70 months. Increased bFGF expression was more frequently found in tumors with low VEGF expression (r = -0.286; P = 0.095). Increased bFGF was associated with smaller tumors (P < 0.001), absence of axillary metastasis (P = 0.003), low S-phase fraction (P < 0.001), and longer recurrence-free survival (RFS; P = 0.0038) and overall survival (OS; P = 0.0316). Vascular endothelial growth factor was a prognostic factor for RFS (P < 0.0001) and OS (P < 0.0001) in univariate and multivariate analyses (RFS: 95% CI, 1.1-1.7; P = 0.036; OS: 95% CI, 1.2-2.2; P = 0.002), whereas bFGF expression was not correlated with RFS or OS. Increased VEGF content was correlated with shorter survival after adjuvant endocrine therapy (RFS, P = 0.0004; OS, P = 0.0009). Patients with estrogen receptor-negative disease were excluded from the analysis. Basic fibroblast growth factor was not a prognostic factor after adjuvant systemic therapy, nor was it related to metastatic site. Expression of VEGF is an independent prognostic factor for patients with primary breast cancer. High bFGF expression was related to good prognostic features and longer survival times, but did not add prognostic information in multivariate analysis. The results might implicate that different angiogenic pathways exist in human breast cancer.