Vascular Epidermal Growth Factor Receptor Research Articles

Vascular endothelial growth factor a inhibition in gastric cancer.

Angiogenesis is a vital process in the progression and metastasis of solids tumors including gastric adenocarcinoma. Tumors induce angiogenesis by secreting proangiogenic molecules such as vascular endothelial growth factor A (VEGF-A), and VEGF-A inhibition has become a common therapeutic strategy for many cancers. Several drugs targeting the VEGF-A pathway have been approved for clinical use in selected solid tumors, and several anti-VEGF-A strategies have been examined for gastric cancer. Phase II studies suggested that bevacizumab, an anti-VEGF antibody, can increase the efficacy of chemotherapy for advanced gastric cancer, but two international phase III trials failed to show an overall survival benefit. Two more recent international phase III trials have examined ramucirumab, an antibody targeting the primary receptor for VEGF-A, as second-line therapy for advanced gastric cancer and found a survival benefit both as single agent therapy and when combined with chemotherapy. Finally, correlative science studies suggest that the VEGF-A pathway may have varying importance in gastric cancer progression depending on ethnicity or race. This article will review the preclinical and clinical studies on the role of the VEGF-A pathway inhibition in gastric cancer.

Advances in the research of a novel mode of the Vascular Epidermal Growth Factor Receptor tyrosine kinase inhibitors

Preclinical studies have proved the important role of angiogenesis in tumor growth, and therefore, inhibiting tumor angiogenesis may be a promising therapeutic modality. Vascular endothelial growth factor (VEGF) is one of the most potent and specific angiogenic factors of tumor-induced angiogenesis. The clinical importance of VEGF for tumor growth is supported by the fact that vascular endothelial growth factor receptor-2 (VEGFR-2) plays a crucial role in the process of cancer angiogenesis and inhibition of VEGF-induced angiogenesis significantly inhibits tumor growth in vivo. In this study, first we introduce the structures of VEGFR-2 inhibitors, and then design a few of new inhibitors containing benzene-pyrazole-lactone-amide moiety. Among these new VEGFR-2 inhibitors, compound 5a exhibited the most potent inhibitory activity with IC50 value of 25.35±1.31nM and 73.81±1.02nM for VEGFR-2 kinase and HUVEC (Human Umbilical Vein Endothelial Cells) respectively, demonstrating that compound 5a is a potential agent for cancer therapy deserving further researching.

Genetic markers of bevacizumab-induced hypertension

There are currently no validated biomarkers predicting bevacizumab treatment outcome or toxicity. We combined biomarker data from six phase III trials of bevacizumab to assess whether genetic variation in vascular endothelial growth factor-A (VEGF-A) pathway or hypertension-related genes are associated with bevacizumab-induced hypertension. Germline DNA was available from 1,631 patients receiving bevacizumab-containing therapy for advanced solid tumors. Overall, 194 white patients had grade 1-4 bevacizumab-induced hypertension. In total, 236 single nucleotide polymorphisms (SNPs) located in VEGF-A, VEGF-A receptors (FLT1 and KDR), and other genes were selected using a SNP tagging approach and genotyped. A logistic regression on individual patient data was performed after adjustment for cancer type and five other covariates. Ten SNPs were associated with bevacizumab-induced hypertension (P ≤ 0.05), but none surpassed the threshold adjusted for multiple testing (P < 0.0002). The most significant VEGF-A pathway SNP was rs1680695 in EGLN3 [allelic odds ratio (OR) 1.50 [95 % confidence interval (Cl) 1.09-2.07], P = 0.012]. Two additional SNPs, rs4444903 in EGF and rs2305949 in KDR, were associated with hypertension (allelic OR 1.57 [95 % CI 1.17-2.11], P = 0.0025; allelic OR 0.62 [95 % CI 0.42-0.93], P = 0.020, respectively) and closely linked to nearby functional variants. Consistent with previous reports, rs11064560 in WNK1 was also associated with bevacizumab-induced hypertension (OR 1.41 [95 % CI 1.04-1.92], P = 0.028). The genes described in this large genetic analysis using pooled datasets warrant further functional investigation regarding their role in mediating bevacizumab-induced hypertension.

Glucose transporter 1 expression accompanies hypoxia sensing in the cyclic canine corpus luteum

The canine corpus luteum (CL) functions as a source of progesterone (P4) and 17β-oestradiol (E2); however, the transport of energy substrates to maintain its high hormonal output has not yet been characterised. This study involved the localisation and temporal distribution of the facilitative glucose transporter 1 and the quantification of the corresponding protein (GLUT1) and gene (SLC2A1) expression. Some GLUT1/SLC2A1 regulatory proteins, such as hypoxia-inducible factor 1α (HIF1A) and fibroblast growth factor 2 (FGF2); mRNAs, such as HIF1A, FGF2 and vascular endothelial growth factor A (VEGFA); and VEGFA receptors 1 and 2 (FLT1 and KDR) were also analysed from days 10 to 70 after ovulation. Additionally, plasma P4 and E2 levels were assessed via chemiluminescence. Moreover, the canine KDR sequence has been cloned, thereby enabling subsequent semi-quantitative PCR analysis. Our results demonstrate time-dependent variations in the expression profile of SLC2A1 during dioestrus, which were accompanied by highly correlated changes (0.84<r<0.98; P<0.03) in the gene expression of HIF1A, VEGF and FLT1 as well as in P4 plasma concentrations. FGF2 mRNA correlated with E2 plasma concentrations (r=0.61; P=0.01). Our data reveal that the glucose transporter is regulated throughout the CL lifespan and suggest that CL depends on the sensing of hypoxia and the status of luteal vascularisation. Moreover, time-dependent expression of GLUT1/SLC2A1 may lie underneath increased metabolic and energetic requirements for sustaining P4 production.

Peritumoral brain edema in angiomatous supratentorial meningiomas: an investigation of the vascular endothelial growth factor A pathway

The aim of this work was to study the vascular endothelial growth factor A (VEGF-A) pathway and peritumoral brain edema (PTBE) through comparison of non-angiomatous and angiomatous meningiomas. Meningiomas are common intracranial tumors, which often have PTBE. VEGF-A is an integral part of PTBE formation and angiogenesis, and the capillary-rich angiomatous meningiomas are known for their PTBE. The VEGF-A receptor VEGFR-2 is responsible for the angiogenic effect of VEGF-A on endothelial cells, which is enhanced by the co-receptor neuropilin-1. Forty non-angiomatous, 22 angiomatous meningiomas, and 10 control tissue samples were collected for the study. Magnetic resonance images were available for 40 non-angiomatous and 10 angiomatous meningiomas. Tissue sections were immunostained for CD34, MIB-1, estrogen- and progesterone receptors. ELISA, chemiluminescence, and RT-qPCR were used for VEGF-A, VEGFR-2, and neuropilin-1 protein and mRNA quantification. Angiomatous meningiomas had larger PTBE (695 vs 218 cm(3) , p = 0.0045) and longer capillary length (3614 vs 605 mm/mm(3) , p < 0.0001). VEGF-A mRNA, neuropilin-1 mRNA, and VEGFR-2 protein levels were higher in angiomatous meningiomas independently of the capillary length (p < 0.05). Neuropilin-1 protein levels were lower in angiomatous meningiomas (p < 0.0001). The VEGF-A pathway and tumor capillary length may be essential for PTBE-formation in meningiomas. Further investigations of this pathway could lead to earlier therapy and targeted pharmacological treatment options.

P.3.c.027 The effect of antipsychotic drug treatment on serum levels of vascular endothelial growth factor (VEGF), sVEGFR-1, and sVEGFR-2 in schizophrenia

Vascular endothelial growth factor-A (VEGF-A) is a crucial mediator of vascular hyperpermeability, angiogenesis, and inflammation, processes intimately involved in tissue repair. Although much emphasis has been placed on understanding the synthesis and stability of VEGF-A mRNA, relatively little attention has been given to the study of the stability and processing of VEGF-A proteins themselves. In recent years, several studies indicated that VEGF-A protein activity is highly controlled through interaction with angiogenic or non-angiogenic mediators. We analyzed mechanisms that might control extracellular VEGF-A processing during wound repair. First, our studies provide evidence that VEGF-A protein is a target of proteases present in the microenvironment of human chronic non-healing wounds. Serine proteases, in particular plasmin cleave VEGF165 and digested VEGF fragments, showed decreased mitogenic activity. Inactivation of the plasmin cleavage site Arg110/Ala111 preserved the structural integrity and increased the angiogenic potency of VEGF165 when tested in an impaired healing mouse model. Secondly, we identified significantly increased levels of the potent VEGF-A inhibitor, the soluble form of the VEGF receptor VEGFR-1 (sVEGFR-1) in non-healing wounds when compared to healing wounds. Wound closure in healing and non-healing wounds correlated significantly with a decline in sVEGFR-1 levels. These observations support the concept that VEGF-A and VEGF-A receptors are important mediators in tissue repair. Further, our data provide mechanisms how VEGF-A-mediated interactions are disturbed during impaired healing.

Airway basal cell vascular endothelial growth factor-mediated cross-talk regulates endothelial cell-dependent growth support of human airway basal cells

The human airway epithelium is a pseudostratified heterogenous layer comprised of ciliated, secretory, intermediate, and basal cells. As the stem/progenitor population of the airway epithelium, airway basal cells differentiate into ciliated and secretory cells to replenish the airway epithelium during physiological turnover and repair. Transcriptome analysis of airway basal cells revealed high expression of vascular endothelial growth factor A (VEGFA), a gene not typically associated with the function of this cell type. Using cultures of primary human airway basal cells, we demonstrate that basal cells express all of the three major isoforms of VEGFA (121, 165 and 189) but lack functional expression of the classical VEGFA receptors VEGFR1 and VEGFR2. The VEGFA is actively secreted by basal cells and while it appears to have no direct autocrine function on basal cell growth and proliferation, it functions in a paracrine manner to activate MAPK signaling cascades in endothelium via VEGFR2-dependent signaling pathways. Using a cytokine- and serum-free co-culture system of primary human airway basal cells and human endothelial cells revealed that basal cell-secreted VEGFA activated endothelium to express mediators that, in turn, stimulate and support basal cell proliferation and growth. These data demonstrate novel VEGFA-mediated cross-talk between airway basal cells and endothelium, the purpose of which is to modulate endothelial activation and in turn stimulate and sustain basal cell growth.

Phosphorylation of Akt and ERK1/2 Is Required for VEGF-A/VEGFR2-Induced Proliferation and Migration of Lymphatic Endothelium

There is growing evidence that vascular endothelial growth factor-A (VEGF-A), a ligand of the receptor tyrosine kinases VEGFR1 and VEGFR2, promotes lymphangiogenesis. However, the underlying mechanisms by which VEGF-A induces the growth of lymphatic vessels remain poorly defined. Here we report that VEGFR2, not VEGFR1, is the primary receptor regulating VEGF-A-induced lymphangiogenesis. We show that specific inhibition of VEGF-A/VEGFR2 signaling with the fully human monoclonal antibody r84 significantly inhibits lymphangiogenesis in MDA-MB-231 tumors. In vitro experiments with primary human dermal lymphatic endothelial cells (LECs) demonstrate that blocking VEGF-A activation of VEGFR2, not VEGFR1, significantly inhibits VEGF-A-induced proliferation and migration of LECs. We show that VEGF-A stimulation of LECs leads to the phosphorylation of VEGFR2 (Tyr 951, 1054, 1059, 1175, and 1214) which subsequently triggers PKC dependent phosphorylation of ERK1/2 and PI3-K dependent phosphorylation of Akt. Additionally, we demonstrate that inhibitors that suppress the phosphorylation of ERK1/2 and Akt significantly block VEGF-A- induced proliferation and migration of LECs. Together, these results shed light on the mechanisms regulating VEGF-A-induced proliferation and migration of LECs, reveal that VEGFR2 is the primary signaling VEGF-A receptor on lymphatic endothelium, and suggest that therapeutic agents targeting the VEGF-A/VEGFR2 axis could be useful in blocking the pathological formation of lymphatic vessels.

Vascular Endothelial Growth Factor Receptor 2 Direct Interaction with Nephrin Links VEGF-A Signals to Actin in Kidney Podocytes

The transmembrane protein nephrin is an essential component of slit diaphragms, the specialized cell junctions that link podocyte foot processes. Podocytes are epithelial cells that surround the glomerular capillaries in the kidney and are necessary for the organ-filtering function. Nephrin signaling complex transduces extracellular cues to the podocyte cytoskeleton and regulates podocyte shape and function. Vascular endothelial growth factor A (VEGF-A) is a required growth factor produced and secreted by podocytes. Accumulating evidence suggests a cross-talk between VEGF-A and nephrin signaling pathways. We previously showed that in vivo nephrin associates with VEGF receptor-2 (VEGFR2), the signaling receptor for VEGF-A. In the present work, we characterized the interaction between nephrin and VEGFR2 in cultured cells and in vitro. We demonstrate that nephrin-VEGFR2 interaction is direct using mass spectrometry, immunoprecipitation, GST-binding assays, and blot overlay experiments. This interaction occurs through VEGFR2 and nephrin cytoplasmic domains. Nephrin-VEGFR2 interaction is modulated by tyrosine phosphorylation of both cytoplasmic domains. Furthermore, the nephrin-VEGFR2 complex involves Nck and actin. VEGF-A signaling via this complex results in decreased cell size. We provide evidence that this multiprotein interaction occurs in cultured podocytes. We propose that the nephrin-VEGFR2 complex acts as a key mediator to transduce local VEGF-A signals to the podocyte actin cytoskeleton, regulating the foot process structure and glomerular filter integrity.

Soluble VEGFR1 (sVEGFR1) as a novel marker of amyotrophic lateral sclerosis (ALS) in the North Indian ALS patients

North Indian patients with amyotrophic lateral sclerosis (ALS) exhibit substantially extended survival time after onset of the disease as compared to their Western counterparts. Earlier, we found that vascular endothelial growth factor-A (VEGF-A) may be associated with increased survival of these patients. We now measured soluble vascular endothelial growth factor receptor-1 (sVEGFR1), an inhibitor receptor for VEGF-A, in these patients with ALS. Patients with sporadic ALS (n = 36) attending the Neurology Outpatient at Post Graduate Institute of Medical Education and Research (PGIMER) at Chandigarh were included on the basis of El Escorial criteria. The sVEGFR1 levels were analyzed in serum of these patients using enzyme-linked immunosorbent assay (ELISA) and compared with normal controls (n = 36). Soluble vascular endothelial growth factor receptor-1 was found to be decreased significantly in serum of patients with ALS. Serum obtained from definite ALS revealed significantly lower sVEGFR1 as compared to probable ALS. However, there was no difference in serum sVEGFR1 levels between male and female patients with ALS. Soluble vascular endothelial growth factor receptor-1 downregulation may result in increased serum VEGF-A reported previously in our patients with ALS and may indicate the activation of compensatory mechanism in response to neurodegeneration. The lower serum sVEGFR1 levels may have a possible clinicopathological association, if not causal, to the extended survival of North Indian patients with ALS; however, the result needs further investigations particularly in comparable Caucasian ALS population.

Impaired vascular permeability regulation caused by the VEGF165b splice variant in pre-eclampsia

Pre-eclampsia is diagnosed by hypertension and proteinuria, probably caused by endothelial dysfunction, resulting in symptoms including oedema, inflammation and altered metabolism. Vascular endothelial growth factor A (VEGF-A) is detected at higher concentrations in plasma from patients with pre-eclampsia than in plasma from normotensive pregnant patients when determined by radioimmunoassay. This study tested the hypothesis that circulating VEGF-A in pre-eclamptic plasma is biologically active in vivo, and aimed to identify specific isoforms responsible for this activity. Plasma from pre-eclamptic (n = 17) and normotensive (n = 10) pregnant women was perfused into Rana mesenteric microvessels, and the subsequent change in microvascular permeability was measured using a single-vessel perfusion micro-occlusion technique. Pre-eclamptic but not normotensive plasma resulted in a 5.25 ± 0.8-fold acute increase in vascular permeability (P = 0.0003). This increase could be blocked by the incubation of plasma with bevacizumab, an antibody to VEGF-A (n = 7; P = 0012), and by VEGF-A receptor inhibition by SU5416 at doses specific to VEGF-A receptor-1 (VEGFR1), but not by the VEGF-A receptor-2 inhibitor, ZM323881. Although VEGF(165) b levels were not significantly altered in the PET samples, the increase in permeability was also inhibited by incubation of pre-eclamptic plasma with an inhibitory monoclonal antibody specific for VEGF₁₆₅b (n=6; P<0.01), or by the addition of placental growth factor 1 (PlGF-1; n = 3; P < 0.001). PlGF-1 was detected at lower concentrations in pre-eclamptic plasma than in normotensive plasma. These findings suggest that circulating VEGF-A levels in pre-eclampsia are biologically active because of a loss of repression of VEGFR1 signalling by PlGF-1, and VEGF₁₆₅b may be involved in the increased vascular permeability of pre-eclampsia.

VEGF-A-induced chemotaxis of CD16+ monocytes is decreased secondary to lower VEGFR-1 expression

BackgroundMonocyte recruitment into the vessel wall is a crucial initial step in vascular repair, arteriogenesis and atherogenesis. Two distinct human monocyte subpopulations can be classified according to their CD14/16 surface expression, namely CD14++CD16−monocytes (CD16−mo) and CD14+CD16+ monocytes (CD16+mo). We investigated different functional properties of the two monocyte subsets. MethodsCD16−/CD16+mo were isolated from human blood by an immunological selection. We assessed monocyte chemokinesis, chemotaxis, adhesion and Vascular-Endothelial Growth Factor (VEGF) receptor expression. Furthermore, generation of reactive oxygen species (ROS) as well as expression of antioxidant enzymes was investigated. ResultsChemokinesis of CD16+mo was decreased compared to CD16−mo (p<0.01). Likewise, adhesion capacity of CD16+mo was weaker (p<0.05). CD16+mo chemotaxis towards the angiogenic ligands vascular endothelial growth factor-A (VEGF-A) and placenta growth factor-1 (PlGF-1) was reduced compared to CD16−mo. VEGFR-1 is the receptor for VEGF-A and PlGF-1 on monocytes. VEGFR-1 protein expression was lower in CD16+mo than in CD16−mo (p<0.05). The impaired VEGF-A- and PlGF-1-induced CD16+mo chemotaxis might therefore be attributed to the reduced VEGFR-1 expression. CD16+mo exhibited less spontaneous ROS production than CD16−mo. Additionally, the antioxidant enzyme manganese superoxide dismutase was expressed at higher levels in CD16+mo (p<0.05); this might partly explain the higher oxidative resistance of CD16+mo. ConclusionThese novel functional differences between CD16−mo and CD16+mo may predict different functional roles of both monocyte subsets in vascular repair, arteriogenesis and atherogenesis.

Effects of Bevacizumab on Autocrine VEGF Stimulation in Bladder Cancer Cell Lines

Introduction: A functional vascular endothelial growth factor A (VEGF-A) autocrine loop is crucial for bladder cancer cell survival. We reasoned that treatment with the anti-VEGF antibody bevacizumab may result either in cell growth prevention or in the cell adaptation to compensate VEGF deprivation. Methods: The cytotoxicity of different levels of bevacizumab and its effect on the gene expression was analyzed in human bladder cancer cell lines. Results: Inhibition of bladder cancer cell proliferation was observed at >2.5 mg/ml of bevacizumab. Non-muscle-invasive bladder cancer cells expressed high concentrations of VEGF-A, and were less susceptible to bevacizumab inhibition. At 0.5 mg/ml (FDA approved concentration) of bevacizumab, cells increase their expression of VEGF-A, VEGF-A receptors and related growth factors. Conclusions: Bevacizumab cytotoxicity is only observed at high concentration, and it is inversely correlated with the basal VEGF-A expression of the bladder cancer cells. This is the first report showing that, at clinical bevacizumab concentrations, cancer cells compensate the VEGF-A blockade, by improving the expression of VEGF-A and related genes, highlighting the need to follow the patient’s adaptation response to bevacizumab treatment.

Complex receptor-ligand dynamics control the response of the VEGF system to protease injury

BackgroundVascular homeostasis and response to injury are dependent on the coordinated activity of growth factors such as vascular endothelial growth factor-A (VEGF). VEGF signaling is mediated by VEGF receptors 1 (VEGFR1) and 2 (VEGFR2). VEGF also binds to extracellular matrix (ECM) and neuropilin (NP), a cell surface glycoprotein that enhances VEGF binding to VEGFR2 while inhibiting VEGF-VEGFR1 interactions. Proteases such as neutrophil elastase release VEGF bound to ECM; however, this results in proteolytic processing of VEGF to a smaller species termed VEGF fragment (VEGFf). We hypothesized that the generation and presence of VEGFf would have significant effects on the binding distribution of VEGF.ResultsWe show that VEGFf, unlike VEGF, does not bind ECM, fibronectin, or NP-1. Using computational simulations, we find that excess VEGFf can lead to increased binding of VEGF to VEGFR2 through VEGFf binding to VEGFR1 and subsequent liberation of NP-1. We show experimentally that VEGF-induced migration has a biphasic response to conversion of VEGF to VEGFf. Simulations suggest that a simple change in VEGFR1 or VEGFR2 complexes are unlikely to be responsible and that a more complex integration of signals is more likely involved.ConclusionsThese findings suggest that proteolytic damage at sites of tissue injury and inflammation has the potential to modulate the VEGF system through a complex process and highlight the need for quantitative analysis to reveal mechanisms of growth factor control.

胰岛素经VEGF-A/VEGFR2途径促进恒河猴视网膜血管内皮细胞的血管新生

Rhesus retinal vascular endothelial cell line RF/6A cells were treated with human insulin. Cell proliferation, migration, and lumen formation, as well as the expressions of vascular endothelial growth factor-A ( VEGF-A ), VEGF-A receptors, and phosphorylated receptors were measured. Insulin promoted RF/6A cell proliferation, migration, and lumen formation ( all P＜0. 01 ). Insulin increased the expression of VEGF-A mRNA and improved its protein activity ( all P＜0. 05 ), and promoted the expression of VEGFR2 mRNA and its phosphorylation ( both P＜0. 01 ). There was no significant difference in the expression of VEGFR1 mRNA among the groups ( P＞0. 05 ). Key words: Insulin; Rhesus retinal vascular endothelial cell line RF/6A; Vascular endothelial growth factor; Vascular endothelial growth factor receptors; Angiogenesis

Microflow of fluorescently labelled red blood cells in tumours expressing single isoforms of VEGF and their response to vascular targeting agents

In this work we studied the functional differences between the microcirculation of murine tumours that express only single isoforms of vascular endothelial growth factor-A (VEGF), namely VEGF120 and VEGF188, and the effect of VEGF receptor tyrosine kinase (VEGF-R TK) inhibition on their functional response to the vascular disrupting agent, combretastatin A-4 phosphate (CA-4-P), using measurement of red blood cell (RBC) velocity by a ‘keyhole’ tracking algorithm. RBC velocities in VEGF188 tumours were unaffected by chronic treatment with a VEGF-R tyrosine kinase inhibitor, SU5416, whereas RBC velocities in VEGF120 tumours were significantly increased compared to control VEGF120 tumours. This effect was accompanied by a reduced tumour vascularisation. Pre-treatment of VEGF120 tumours with SU5416 made them much more resistant to CA-4-P treatment, with a RBC velocity response that was very similar to that of the more mature vasculature of the VEGF188 tumours. This study shows that vascular normalisation following anti-angiogenic treatment with a VEGF-R tyrosine kinase inhibitor reduced the response of a previously sensitive tumour line to CA-4-P.

Cetuximab as Second-Line Therapy in Patients with Metastatic Esophageal Adenocarcinoma: A Phase II Southwest Oncology Group Study (S0415)

Esophageal adenocarcinomas commonly express the epidermal growth factor receptor. This trial assessed the 6-month overall survival probability in metastatic esophageal cancer patients treated with cetuximab as second-line therapy. This was a multicenter, open-label phase II study of single-agent cetuximab for metastatic esophageal adenocarcinoma patients who failed one prior chemotherapy regimen. Adequate organ function and Zubrod performance status of 0 to 2 were required. Patients received cetuximab 400 mg/m intravenously (IV) on week 1 and 250 mg/m IV weekly thereafter. The primary objective was to determine 6-month overall survival. Secondary end points included progression-free survival, response rate, and toxicity. Tumor tissue was collected for correlative studies. Sixty-three patients were registered, with eight ineligible or never treated. Fifty-five eligible patients (49 men, 6 women; median age = 61.2 years [range, 30.7-88.5]) were enrolled. Twenty patients survived more than 6 months for a 6-month overall survival rate of 36% (95% confidence interval [CI]: 24-50%). The median overall survival was 4.0 months (95% CI: 3.2-5.9). Median progression-free survival was 1.8 months (95% CI: 1.7-1.9). One partial response and two unconfirmed partial responses were observed. Two patients experienced grade 4 fatigue. There was one treatment-related death due to pneumonitis. Germline polymorphisms of epidermal growth factor receptor, epidermal growth factor, interleukin (IL)-8, cyclooxygenase (COX)-2, vascular epidermal growth factor receptor (VEGF), CCND1, neuropilin 1 (NRP1), and K-ras mutational status were not associated with response or survival. The 6-month overall survival rate of 36% observed on this study failed to meet the primary survival objective. Thus, cetuximab alone cannot be recommended in the second-line treatment of metastatic esophageal cancer.

Intersegmental vessel formation in zebrafish: requirement for VEGF but not BMP signalling revealed by selective and non-selective BMP antagonists.

Bone morphogenetic proteins (BMPs) were first identified through their role in inducing bone and cartilage formation, but many other important functions have since been ascribed to BMPs, including dorsoventral patterning, angiogenesis and tissue homeostasis. Using dorsomorphin and LDN193189, selective small molecule inhibitors of BMP signalling, we investigated the role of BMP signalling in early vascular patterning in zebrafish. The effects of dorsomorphin and LDN193189 on vascular endothelial growth factor-a (VEGF) and BMP signalling in developing zebrafish and in human pulmonary artery endothelial cells were determined using confocal microscopy, Western blotting and quantitative PCR. We showed that dorsomorphin, similar to the VEGF inhibitor SU5416, strongly inhibits intersegmental vessel formation in zebrafish and that this is due to inhibition of VEGF activation of VEGF receptor 2 (VEGFR2), leading to reduced VEGF-induced phospho-ERK (extracellular regulated kinase) 1/2 and VEGF target gene transcription. These effects occurred at concentrations of dorsomorphin that block BMP signalling. We also showed that LDN193189, an analogue of dorsomorphin, more potently blocks BMP signalling but has no effect on VEGF signalling in zebrafish and does not disrupt early vascular patterning. Dorsomorphin inhibits both BMP and VEGF signalling, whereas LDN193189 is a more selective BMP antagonist. Results obtained in cardiovascular studies using dorsomorphin need to be interpreted with caution, and use of LDN193189 would be preferable due to its selectivity. Our data also suggest that BMP signalling is dispensable for early patterning of intersegmental vessels in zebrafish.

Expression of vascular endothelial growth factor A during ligand-induced down-regulation of luteinizing hormone receptor in the ovary

Vascular endothelial growth factor A (VEGF-A) is one of the most important regulators of ovarian angiogenesis. In this study, we examined the temporal relationship between VEGF-A and luteinizing hormone receptor (LHR) mRNA expression during ligand-induced down-regulation of LHR. Immature female rats were treated with pregnant mare's serum gonadotropin followed by 25 IU hCG 56 h later (day 0). On day 5, treatment with hCG (50 IU) to down-regulate LHR showed a temporal decrease in VEGF-A mRNA and protein levels in parallel with decreasing LHR mRNA. This effect was specific since the expression of CYP11A1 mRNA showed no decline. Examination of VEGF-A mRNA expression, using in situ hybridization histochemistry with 35S-labeled antisense VEGF-A mRNA probe, showed intense signal in the corpora lutea on day 5. Treatment with 50 IU hCG to down-regulate LHR mRNA showed a decline in the intensity of VEGF-A mRNA in the corpora lutea. VEGF-A mRNA expression returned to control level 53 h later when the expression of LHR mRNA also recovered. These results show that the transient down-regulation of VEGF-A mRNA and protein closely parallels the ligand-induced down-regulation of LHR mRNA. The present study establishes a close association between VEGF-A and LHR mRNA expression, suggesting the possibility that VEGF-A-induced vascularization of the ovary is dictated by the expression of LHR and this might play a regulatory role in ovarian physiology.

Vascular endothelial growth factor-A isoform and (co)receptor expression are differentially regulated by 17β-oestradiol in the ovariectomised mouse uterus

The angiogenic effects of 17beta-oestradiol (E(2)) in the mouse endometrium are mediated by vascular endothelial growth factor-A (VEGFA). We analysed the temporal and spatial changes in VEGFA isoform and (co)receptor expression in ovariectomised mouse uteri following E(2) treatment. VEGFA isoform and receptor mRNA were quantified in whole uterine tissue collected 2, 6, 12 and 24 h after E(2) or vehicle treatment. Laser capture microdissection was used to investigate mRNA expression in epithelial, stromal and myometrial tissues separately. Endothelial cell proliferation, VEGFA and VEGF receptor-2 (VEGFR2) protein were visualised using immunohistochemistry. Endometrial endothelial cell proliferation was only observed 24 h after E(2) treatment. In whole uterine tissue, total Vegfa, Vegfa(164) and Vegfa(120) mRNA expression increased 2 h post E(2) treatment, and then decreased by 24 h. Vegfa(188) expression was lower in E(2)-treated animals at all time points relative to control animals. Vegfr2 and neuropilin-1 (Nrp1) mRNA expression did not change following E(2) treatment; Nrp2 expression decreased by 24 h. When uterine compartments were considered separately at 24 h post E(2) or vehicle, stromal Vegfa(120), Vegfa(188) and Vegfr2 mRNA expression and myometrial Vegfa(120) and Vegfa(188) mRNA expression were reduced in E(2)-treated mice relative to controls, whereas epithelial Vegfa(188) mRNA expression increased. The highest VEGFA immunoexpression was observed in luminal epithelium; expression increased at 24 h relative to other time points. No changes were noted in VEGFR2 immunoexpression among treatment groups. We have provided the first evidence that VEGFA isoform and receptor mRNA expression are differentially regulated by E(2) in different uterine cell compartments.