Vascular Endothelial Growth Factor Receptor Pathways Research Articles

Clinical course and vascular endothelial growth factor signaling system expression in maxillary angiosarcoma: A case report.

Maxillary angiosarcoma, an aggressive tumor derived from vascular endothelial cells, is very rare. Recently, antivascular endothelial growth factor (VEGF) therapies have attracted considerable attention. We describe the clinical course of a patient with maxillary angiosarcoma and discuss the expression of VEGF signaling molecules assessed via immunohistological analysis. An 81-year-old man presented with an aggressive tumor in the left maxillary sinus. Biopsy revealed atypical nuclear cell proliferation, and the tumor was suspected to be a sarcoma. The maxillary malignancy was treated using a multidisciplinary approach with a combination of surgery, radiotherapy, and regional chemotherapy. Examination of the specimen obtained in the first surgery revealed maxillary angiosarcoma, found to be positive for CD31, while negative for CD34, D2-40, and factor Ⅷ. Although no pathological residual tumor was observed after the planned wide surgery, cervical lymph node and distant metastases occurred. The patient died 24 months after the first surgery. Staining revealed VEGF receptor (VEGFR) 1, VEGFR2, phosphorylated Ak strain transforming, mitogen-activated protein kinase, and signal transducer and activator of transcription 3 positivity. Although our findings do not indicate that anti-VEGF therapy is beneficial for treating maxillary angiosarcomas, we found that VEGFR signaling pathways were activated in maxillary angiosarcomas similar to angiosarcomas originating at other sites. Herein, we report a case of maxillary angiosarcoma, focused on VEGFR and signaling pathway activation. To our knowledge, this is the first report to describe VEGFR system immunostaining findings in maxillary angiosarcoma.

PEDF inhibits VEGF-induced vascular leakage through binding to VEGFR2 in acute myocardial infarction

Pigment epithelium-derived factor (PEDF) could bind to vascular endothelial growth factor receptor 2 (VEGFR2) and inhibit its activation induced by VEGF. But how PEDF affects VEGFR2 pathway is still poorly understood. In this study, we elucidated the precise mechanism underlying the interaction between PEDF and VEGFR2, and subsequently corroborated our findings using a rat AMI model. PEDF prevented endocytosis of VE-cadherin induced by hypoxia, thereby protecting the endothelium integrity. A three-dimensional model of the VEGFR2-PEDF complex was constructed by protein-protein docking method. The results showed that the VEGFR2-PEDF complex was stable during the simulation. Hydrogen bonds, binding energy and binding modes were analyzed during molecular dynamics simulations, which indicated that hydrogen bonds and hydrophobic interactions were important for the recognition of VEGFR2 with PEDF. In addition, the results from exudation of fibrinogen suggested that PEDF inhibits vascular leakage in acute myocardial infarction and confirmed the critical role of key amino acids in the regulation of endothelial cell permeability. This observation is also supported by echocardiography studies showing that the 34mer peptide sustained cardiac function during acute myocardial infarction. Besides, PEDF and 34mer could inhibit the aggregation of myofiber in the heart and promoted the formation of a dense cell layer in cardiomyocytes, which suggested that PEDF and 34mer peptide protect against AMI-induced cardiac dysfunction. These results suggest that PEDF inhibits the phosphorylation of downstream proteins, thereby preventing vascular leakage, which provides a new therapeutic direction for the treatment of acute myocardial infarction. Communicated by Ramaswamy H. Sarma

Ishophloroglucin A Ameliorates VEGF-Induced Epithelial-Mesenchymal Transition via VEGFR2 Pathway Inhibition in Microgravity-Stimulated Human Retinal Pigment Epithelial Cells.

Microgravity stimulation is associated with retinal pigment epithelial (RPE) cells that transition to mesenchymal cells (EMT), and these pathological changes cause visual impairment. Vascular endothelial growth factor (VEGF) is produced from the RPE and contributes to photoreceptor survival. However, changes in VEGF production and function under microgravity stimulation are unknown. In this study, we verified that microgravity stimulation changed the morphological characteristics of human RPE cells (ARPE19 cells) and the expression of actin cytoskeleton regulators, which are related to excessive VEGF expression. Interestingly, microgravity stimulation increased not only the production of VEGF but also the expression of EMT markers. Previously, we studied the potential of ishophloroglucin A (IPA), a phlorotannin, as an antioxidant. In silico results confirmed that IPA could structurally bind to VEGF receptor 2 (VEGFR2) among VEGFRs and inhibit the VEGF pathway. IPA significantly decreased VEGF production and EMT marker expression in microgravity-stimulated cells. It also significantly reduced excessive cell migration in VEGF-induced EMT. Overall, our findings suggested that IPA treatment decreased VEGF production and EMT marker expression in microgravity-stimulated or VEGF-treated ARPE19 cells, and this decrease in EMT could restore excessive cell migration by inhibiting the VEGF/VEGFR2 pathway. Therefore, it is a potential therapeutic candidate for angiogenesis-related eye diseases.

Treatment with a VEGFR-2 antibody results in intra-tumor immune modulation and enhances anti-tumor efficacy of PD-L1 blockade in syngeneic murine tumor models.

Prolonged activation of vascular endothelial growth factor receptor-2 (VEGFR-2) due to mis-regulation of the VEGF pathway induces aberrant blood vessel expansion, which supports growth and survival of solid tumors. Therapeutic interventions that inhibit the VEGFR-2 pathway have therefore become a mainstay of cancer treatment. Non-clinical studies have recently revealed that blockade of angiogenesis can modulate the tumor microenvironment and enhance the efficacy of concurrent immune therapies. Ramucirumab is an FDA-approved anti-angiogenic antibody that inhibits VEGFR-2 and is currently being evaluated in clinical studies in combination with anti-programmed cell death (PD-1) axis checkpoint inhibitors (pembrolizumab, durvalumab, or sintilimab) across several cancer types. The purpose of this study is to establish a mechanistic basis for the enhanced activity observed in the combined blockade of VEGFR-2 and PD-1-axis pathways. Pre-clinical studies were conducted in murine tumor models known to be responsive to anti-PD-1 axis therapy, using monoclonal antibodies that block mouse VEGFR-2 and programmed death-ligand 1 (PD-L1). Combination therapy resulted in enhanced anti-tumor activity compared to anti-PD-L1 monotherapy. VEGFR-2 blockade at early timepoints post-anti-PD-L1 therapy resulted in a dose-dependent and transient enhanced infiltration of T cells, and establishment of immunological memory. VEGFR-2 blockade at later timepoints resulted in enhancement of anti-PD-L1-driven immune cell infiltration. VEGFR-2 and PD-L1 monotherapies induced both unique and overlapping patterns of immune gene expression, and combination therapy resulted in an enhanced immune activation signature. Collectively, these results provide new and actionable insights into the mechanisms by which concurrent VEGFR-2 and PD-L1 antibody therapy leads to enhanced anti-tumor efficacy.

Proteome Changes Associated with the VEGFR Pathway and Immune System in Diabetic Macular Edema Patients at Different Diabetic Retinopathy Stages

Purpose Diabetic macular edema (DME) is a major cause of vision loss in all stages of diabetic retinopathy (DR). However, there is limited recognition of aqueous humor (AH) proteome profiles of DME patients at different DR stages. In this study, we aimed to investigate the AH proteome changes between DME patients at the nonproliferative diabetic retinopathy (NPDR) stage and those at the proliferative diabetic retinopathy (PDR) stage. Methods A label-free data-independent acquisition based liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis was performed to profile the abundances of AH proteins in 73 eyes from DME patients at different DR stages. Enzyme-linked immunosorbent assay (ELISA) was used to confirm the proteomics results with AH samples from non-diabetic patients and DME patients at the NPDR or PDR stage. Results LC-MS/MS results showed significantly changed expression of 308 proteins between DME patients in the NPDR and PDR groups. Compared to the NPDR group, the proteins relatively up-regulated in the PDR group are involved in the immune system and/or negative regulation of the cell cycle, while proteins relatively down-regulated in the PDR group are associated with the vascular endothelial growth factor receptor (VEGFR) pathway and/or metabolism. ELISA results further verified the proteomic result of down-regulated expression of the immune-associated protein cystatin C (CST3) in the PDR group compared to that in the NPDR and non-diabetic groups. Conclusions In this study, we reported for the first time the decreased abundances of AH proteins associated with the VEGFR pathway and both down- and up-regulated expression of AH proteins associated with the immune system in the PDR group compared to that in the NPDR group. Furthermore, we found negative correlations of immune-associated protein, CST3 concentration in AH with DR severity and central retinal thickness, suggesting CST3 as a promising target independent of the VEGFR pathway in DME-involved DR treatment.

Aging-Associated miR-217 Aggravates Atherosclerosis and Promotes Cardiovascular Dysfunction.

microRNAs are master regulators of gene expression with essential roles in virtually all biological processes. miR-217 has been associated with aging and cellular senescence, but its role in vascular disease is not understood. Approach and Results: We have used an inducible endothelium-specific knock-in mouse model to address the role of miR-217 in vascular function and atherosclerosis. miR-217 reduced NO production and promoted endothelial dysfunction, increased blood pressure, and exacerbated atherosclerosis in proatherogenic apoE-/- mice. Moreover, increased endothelial miR-217 expression led to the development of coronary artery disease and altered left ventricular heart function, inducing diastolic and systolic dysfunction. Conversely, inhibition of endogenous vascular miR-217 in apoE-/- mice improved vascular contractility and diminished atherosclerosis. Transcriptome analysis revealed that miR-217 regulates an endothelial signaling hub and downregulates a network of eNOS (endothelial NO synthase) activators, including VEGF (vascular endothelial growth factor) and apelin receptor pathways, resulting in diminished eNOS expression. Further analysis revealed that human plasma miR-217 is a biomarker of vascular aging and cardiovascular risk. Our results highlight the therapeutic potential of miR-217 inhibitors in aging-related cardiovascular disease.

Vascular Endothelial Growth Factor 165-Binding Heparan Sulfate Promotes Functional Recovery From Cerebral Ischemia.

Although VEGF165 (vascular endothelial growth factor-165) is able to enhance both angiogenesis and neurogenesis, it also increases vascular permeability through the blood-brain barrier. Heparan sulfate (HS) sugars play important roles in regulating VEGF bioactivity in the pericellular compartment. Here we asked whether an affinity-purified VEGF165-binding HS (HS7) could augment endogenous VEGF activity during stroke recovery without affecting blood-brain barrier function. Both rat brain endothelial cell line 4 and primary rat neural progenitor cells were used to evaluate the potential angiogenic and neurogenic effects of HS7 in vitro. For in vivo experiments, male Sprague-Dawley rats were subjected to 100 minutes of transient focal cerebral ischemia, then treated after 4 days with either PBS or HS7. One week later, infarct volume, behavioral sequelae, immunohistochemical markers of angiogenesis and neural stem cell proliferation were assessed. HS7 significantly enhanced VEGF165-mediated angiogenesis in rat brain endothelial cell line 4 brain endothelial cells, and increased the proliferation and differentiation of primary neural progenitor cells, both via the VEGFR2 (vascular endothelial growth factor receptor 2) pathway. Intracerebroventricular injection of HS7 improved neurological outcome in ischemic rats without changing infarct volumes. Immunostaining of the compromised cerebrum demonstrated increases in collagen IV/Ki67 and nestin/Ki67 after HS7 exposure, consistent with its ability to promote angiogenesis and neurogenesis, without compromising blood-brain barrier integrity. A VEGF-activating glycosaminoglycan sugar, by itself, is able to enhance endogenous VEGF165 activity during the post-ischemic recovery phase of stroke.

Pharmacological Potential of Small Molecules for Treating Corneal Neovascularization.

Under healthy conditions, the cornea is an avascular structure which allows for transparency and optimal visual acuity. Its avascular nature is maintained by a balance of proangiogenic and antiangiogenic factors. An imbalance of these factors can result in abnormal blood vessel proliferation into the cornea. This corneal neovascularization (CoNV) can stem from a variety of insults including hypoxia and ocular surface inflammation caused by trauma, infection, chemical burns, and immunological diseases. CoNV threatens corneal transparency, resulting in permanent vision loss. Mainstay treatments of CoNV have partial efficacy and associated side effects, revealing the need for novel treatments. Numerous natural products and synthetic small molecules have shown potential in preclinical studies in vivo as antiangiogenic therapies for CoNV. Such small molecules include synthetic inhibitors of the vascular endothelial growth factor (VEGF) receptor and other tyrosine kinases, plus repurposed antimicrobials, as well as natural source-derived flavonoid and non-flavonoid phytochemicals, immunosuppressants, vitamins, and histone deacetylase inhibitors. They induce antiangiogenic and anti-inflammatory effects through inhibition of VEGF, NF-κB, and other growth factor receptor pathways. Here, we review the potential of small molecules, both synthetics and natural products, targeting these and other molecular mechanisms, as antiangiogenic agents in the treatment of CoNV.

Anti-VEGF Drugs in the Treatment of Multiple Myeloma Patients.

The interaction between the bone marrow microenvironment and plasma cells plays an essential role in multiple myeloma progression and drug resistance. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway in vascular endothelial cells activates and promotes angiogenesis. Moreover, VEGF activates and promotes vasculogenesis and vasculogenic mimicry when it interacts with VEGF receptors expressed in precursor cells and inflammatory cells, respectively. In myeloma bone marrow, VEGF and VEGF receptor expression are upregulated and hyperactive in the stromal and tumor cells. It has been demonstrated that several antiangiogenic agents can effectively target VEGF-related pathways in the preclinical phase. However, they are not successful in treating multiple myeloma, probably due to the vicarious action of other cytokines and signaling pathways. Thus, the simultaneous blocking of multiple cytokine pathways, including the VEGF/VEGFR pathway, may represent a valid strategy to treat multiple myeloma. This review aims to summarize recent advances in understanding the role of the VEGF/VEGFR pathway in multiple myeloma, and mainly focuses on the transcription pathway and on strategies that target this pathway.

Fisetin inhibits vascular endothelial growth factor-induced angiogenesis in retinoblastoma cells.

Fisetin is a small phytochemical molecule with antitumor activity. Angiogenesis is a basic process that occurs during tumor growth and metastasis. The vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway is a key regulator of angiogenesis. The aim of the present study was to evaluate whether fisetin affects angiogenesis through the VEGFR pathway. In the present study, Y79 cells were treated with 100 ng/ml VEGF in the presence of fisetin at concentrations of 0, 25, 50 and 100 µM. A Cell Counting Kit-8 assay was used to detect proliferation and the Transwell and Matrigel assays were used to assess cell migration and invasion, respectively. Reverse transcription-quantitative polymerase chain reaction analysis was applied to measure the expression level of VEGFR mRNA and western blot analysis was used to measure the protein expression of VEGFR. An immunofluorescence assay was used to detect the expression of VEGFR. Angiogenesis in vitro was assessed by a tube formation assay. The results demonstrated that fisetin significantly inhibited the proliferation of Y79 cells in a time- and dose-dependent manner. Fisetin also inhibited the migration and invasion of Y79 cells in a dose-dependent manner. Furthermore, fisetin inhibited the expression of VEGFR in Y79 cells in a dose-dependent manner and tumor angiogenesis in vitro. Thus, fisetin was found to inhibit angiogenesis via inhibition of the VEGF/VEGFR signaling pathway, and could be used as a candidate drug to inhibit angiogenesis in retinoblastoma.

The ACTIVE study protocol: apatinib or placebo plus gefitinib as first-line treatment for patients with EGFR-mutant advanced non-small cell lung cancer (CTONG1706)

BackgroundGefitinib, as the first epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) approved for the treatment of advanced non-small cell lung cancer (NSCLC), has been proved to significantly improve the progression-free survival (PFS) in the first-line setting but suffers from resistance 7–10 months after treatment initiation. Apatinib (YN968D1), a potent vascular endothelial growth factor receptor (VEGFR) 2-TKI, specifically binds to VEGFR2 and leads to anti-angiogenetic and anti-neoplastic effect. Concurrent inhibition of VEGFR and EGFR pathways represents a rational approach to improve treatment responses and delay the onset of treatment resistance in EGFR-mutant NSCLC. This ACTIVE study aims to assess the combination of apatinib and gefitinib as a new treatment approach for EGFR-mutant NSCLC as a first-line setting.MethodsThis multicenter, randomized, double-blind, placebo-controlled phase III study (NCT02824458) has been designed to assess the efficacy and safety of apatinib or placebo combined with gefitinib as a first-line treatment for patients with EGFR-mutant advanced NSCLC. A total of 310 patients with EGFR-mutation (19del or 21L858R), pathological stage IIIB to IV non-squamous NSCLC were to be enrolled. The primary endpoint is investigator assessment of PFS, and the secondary endpoints include independent radiological central (IRC)-confirmed PFS, overall survival (OS), objective response rate (ORR), disease control rate (DCR), time to progressive disease (TTPD), duration of response (DoR), quality of life (QoL) and safety. The patients are randomized in a 1:1 ratio to receive gefitinib (250 mg, p.o. q.d.) plus apatinib (500 mg, p.o. q.d.) or gefitinib plus placebo, given until disease progression or intolerable adverse events. Exploratory biomarker analysis will be performed. This study is being conducted across China and comprises of 30 participating centers. Enrollment commenced in August 2017 and finished in December 2018, most of the patients are in the follow-up period.Anticipated outcomes and significanceThe present study will be the first to evaluate the efficacy and safety profile of the combination of apatinib plus gefitinib as a first-line therapy for patients with EGFR-positive advanced non-squamous NSCLC. Importantly, this trial will provide comprehensive evidence on the treatment of EGFR-TKIs combined with antiangiogenic therapy.Trial registration Clinicaltrials.gov NCT02824458. Registered 23 June 2016

Anti-VEGFR2 therapy delays growth of preclinical pediatric tumor models and enhances anti-tumor activity of chemotherapy.

Vascular endothelial growth factor receptor 2 (VEGFR2) is an attractive therapeutic target in solid malignancies due to its central role in tumor angiogenesis. Ramucirumab (Cyramza®, LY3009806) is a human monoclonal antibody specific for VEGFR2 approved for several adult indications and currently in a phase 1 clinical trial for pediatric patients with solid tumors (NCT02564198). Here, we evaluated ramucirumab in vitro and the anti-murine VEGFR2 antibody DC101 in vivo with or without chemotherapy across a range of pediatric cancer models. Ramucirumab abrogated in vitro endothelial cord formation driven by cancer cell lines representing multiple pediatric histologies; this response was independent of the origin of the tumor cell-line. Several pediatric cancer mouse models responded to single agent DC101-mediated VEGFR2 inhibition with tumor growth delay. Preclinical stable disease and partial xenograft regressions were observed in mouse models of Ewing’s sarcoma, synovial sarcoma, neuroblastoma, and desmoplastic small round cell tumor treated with DC101 and cytotoxic chemotherapy. In contrast, DC101 treatment in osteosarcoma models had limited efficacy alone or in combination with chemotherapeutics. Our data indicate differential efficacy of targeting the VEGFR2 pathway in pediatric models and support the continued evaluation of VEGFR2 inhibition in combination with cytotoxic chemotherapy in multiple pediatric indications.

Soluble Tei2 fusion protein inhibits retinopathy of prematurity occurrence via regulation of the Ang/Tie2 pathway.

The aim of the present study was to investigate the potential mechanism of retinopathy of prematurity (ROP) using an oxygen-induced retinopathy (OIR) mouse model. For experiments, mice were divided into either the OIR group or control group. Fluorescein isothiocyanate-dextran cardiac perfusion and stretched retina preparation were performed. The total retina area, area of instillation, density of microvascular network, area of new blood vessels, vein width and the tortuosity of arteries were measured. Next, mice were randomly assigned into the PBS, soluble TEK receptor tyrosine kinase (sTie2)-fusion protein (Fc), angiopoietin 1 (Ang1), ranibizumab, ranibizumab + sTie2-Fc and ranibizumab + Ang1 treatment groups. Following housing for 5 days, the body weight of each mouse was recorded. Mice in the OIR group presented smaller total retina area and larger area of instillation, larger area of new blood vessels, and higher microvascular network density compared with the control PBS group. Obvious retinal vein dilatation and arterial tortuosity were identified in the OIR group. The amount of endotheliocyte nuclei of new vessels beyond the inner limiting membrane was larger in the OIR group compared with the control group. Furthermore in the next set of experiments, a larger area of instillation, smaller area of new blood vessels and decreased amount of endotheliocyte nuclei of new vessels were observed in the sTie2-Fc group, Ang1 group, ranibizumab group, ranibizumab + sTie2-Fc group and ranibizumab + Ang1 group compared with the PBS group. Specifically, the ranibizumab + sTie2-Fc group and ranibizumab + Ang1 group demonstrated markedly reduced retina instillation area and microvascular network density in the instillation area. Total retina area and body weight following 10 days of the experiment for the ranibizumab group were significantly lower compared with other groups. In conclusion, the combined regulation of the Ang/Tie2 and the vascular endothelial growth factor (VEGF)/VEGF receptor pathways markedly increased the efficacy of treatment with retinal neovascularization (RNV). Regulation of these pathways has a potential for treating RNV, in particular ROP.

Multiscale modeling reveals angiogenesis-induced drug resistance in brain tumors and predicts a synergistic drug combination targeting EGFR and VEGFR pathways

BackgroundExperimental studies have demonstrated that both the extracellular vasculature or microenvironment and intracellular molecular network (e.g., epidermal growth factor receptor (EGFR) signaling pathway) are important for brain tumor growth. Additionally, some drugs have been developed to inhibit EGFR signaling pathways. However, how angiogenesis affects the response of tumor cells to drug treatment has rarely been mechanistically studied. Therefore, a multiscale model is required to investigate such complex biological systems that contain interactions and feedback among multiple levels.ResultsIn this study, we developed a single cell-based multiscale spatiotemporal model to simulate vascular tumor growth and the drug response based on the vascular endothelial growth factor receptor (VEGFR) signaling pathway, the EGFR signaling pathway and the cell cycle as well as several microenvironmental factors that determine cell fate switches in a temporal and spatial context.By incorporating the EGFRI treatment effect, the model showed an interesting phenomenon in which the survival rate of tumor cells decreased in the early stage but rebounded in a later stage, revealing the emergence of drug resistance. Moreover, we revealed the critical role of angiogenesis in acquired drug resistance, since inhibiting blood vessel growth using a VEGFR inhibitor prevented the recovery of the survival rate of tumor cells in the later stage.We further investigated the optimal timing of combining VEGFR inhibition with EGFR inhibition and predicted that the drug combination targeting both the EGFR pathway and VEGFR pathway has a synergistic effect. The experimental data validated the prediction of drug synergy, confirming the effectiveness of our model. In addition, the combination of EGFR and VEGFR genes showed clinical relevance in glioma patients.ConclusionsThe developed multiscale model revealed angiogenesis-induced drug resistance mechanisms of brain tumors to EGFRI treatment and predicted a synergistic drug combination targeting both EGFR and VEGFR pathways with optimal combination timing. This study explored the mechanistic and functional mechanisms of the angiogenesis underlying tumor growth and drug resistance, which advances our understanding of novel mechanisms of drug resistance and provides implications for designing more effective cancer therapies.

Gintonin-mediated release of astrocytic vascular endothelial growth factor protects cortical astrocytes from hypoxia-induced cell damages

BackgroundGintonin is a ginseng-derived exogenous ligand of the G protein-coupled lysophosphatidic acid (LPA) receptor. We previously reported that gintonin stimulates gliotransmitter release in primary cortical astrocytes. Astrocytes play key roles in the functions of neurovascular systems. Although vascular endothelial growth factor (VEGF) is known to influence the normal growth and maintenance of cranial blood vessels and the nervous system, there is little information about the effect of gintonin on VEGF regulation in primary astrocytes, under normal and hypoxic conditions. MethodsUsing primary cortical astrocytes of mice, the effects of gintonin on the release, expression, and distribution of VEGF were examined. We further investigated whether the gintonin-mediated VEGF release protects astrocytes from hypoxia. ResultsGintonin administration stimulated the release and expression of VEGF from astrocytes in a concentration- and time-dependent manner. The gintonin-mediated increase in the release of VEGF was inhibited by the LPA1/3 receptor antagonist, Ki16425; phospholipase C inhibitor, U73122; inositol 1,4,5-triphosphate receptor antagonist, 2-APB; and intracellular Ca2+ chelator, BAPTA. Hypoxia further stimulated astrocytic VEGF release. Gintonin treatment stimulated additional VEGF release and restored cell viability that had decreased due to hypoxia, via the VEGF receptor pathway. Altogether, the regulation of VEGF release and expression and astrocytic protection mediated by gintonin under hypoxia are achieved via the LPA receptor–VEGF signaling pathways. ConclusionThe present study shows that the gintonin-mediated regulation of VEGF in cortical astrocytes might be neuroprotective against hypoxic insults and could explain the molecular basis of the beneficial effects of ginseng on the central nervous system.

Glycosylation controls cooperative PECAM-VEGFR2-β3 integrin functions at the endothelial surface for tumor angiogenesis.

Most of the angiogenesis inhibitors clinically used in cancer treatment target the vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) pathway. However, the current strategies for treating angiogenesis have limited efficacy. The issue of how to treat angiogenesis and endothelial dysfunction in cancer remains a matter of substantial debate. Here we demonstrate a glycosylation-dependent regulatory mechanism for tumor angiogenesis. St6gal1-/- mice, lacking the α2,6-sialylation enzyme, were shown to exhibit impaired tumor angiogenesis through enhanced endothelial apoptosis. In a previous study, St6gal1-/- endothelial cells exhibited a reduction in the cell surface residency of platelet endothelial cell adhesion molecule (PECAM). In this study, we found that cooperative functionality of PECAM-VEGFR2-integrin β3 was disturbed in St6gal1-/- mice. First, cell surface PECAM-VEGFR2 complexes were lost, and both VEGFR2 internalization and the VEGFR-dependent signaling pathway were enhanced. Second, enhanced anoikis was observed, suggesting that the absence of α2,6-sialic acid leads to dysregulated integrin signaling. Notably, ectopic expression of PECAM increased cell surface integrin-β3, indicating that the reduction of cell surface integrin-β3 involves loss-of-endothelial PECAM. The results suggest that the cell surface stability of these glycoproteins is significantly reduced by the lack of α2,6-sialic acid, leading to abnormal signal transduction. The present findings highlight that α2,6-sialylation is critically involved in endothelial survival by controlling the cell surface stability and signal transduction of angiogenic molecules, and could be a novel target for anti-angiogenesis therapy.

PBA2 exhibits potent anti-tumor activity via suppression of VEGFR2 mediated-cell proliferation and angiogenesis

VEGFR2 (vascular endothelial growth factor receptor 2) is the main trigger of VEGF-mediated angiogenic signal and targeting VEGFR2 pathway to inhibit tumor angiogenesis represents a promising strategy for cancer therapy. We elucidated that a novel compound, PBA2 exhibited potent anti-tumor effects both in vitro and in vivo with limited toxicity. ELISA assay revealed that PBA2 had a strong suppressive activity against VEGFR2 related to angiogenesis. Furthermore, PBA2 considerably disrupted tube formation of endothelial cells in vitro and systemic administration of PBA2 exerted decreased tumor angiogenesis in vivo. Functional tests demonstrated that PBA2 concentration-dependently impeded the migration and proliferation of endothelial cells. PBA2 had no effects on the expression level of VEGF both in the detected cancer cells and endothelial cells. VEGFR2 and its downstream Akt and Erk pathways were blocked by PBA2 in a concentration-dependent manner both in vitro and in vivo. Overall, we first demonstrated that PBA2, targeting VEGFR2 related to angiogenesis, presented remarkable anti-angiogenic and anti-tumor activities through attenuating VEGFR2 mediated pathway in vitro and in vivo with limited toxicity. These observations posed that PBA2 could be a potential drug candidate for developing anti-angiogenic tyrosine kinase inhibitor in cancer therapy.

Effect of STAT-3-mediated non-dependent VEGFR-2 pathway on radiosensitivity of non-small cell lung cancer cells

Objective To investigate the effect of signal transducer and activator of transcription-3(STAT-3)-mediated non-dependent vascular endothelial growth factor receptor-2(VEGFR-2) pathway on the radiosensitivity of non-small cell lung cancer (NSCLC) cells and its possible mechanism. Methods NSCLC cells were divided into control group, apatinib (VEGFR-2 inhibitor) group, apatinib+ S3I-201(STAT-3 inhibitor) group, radiation (RT) group, RT+ apatinib group, and RT+ apatinib+ S3I-201 group. Q-PCR and Western blot were used to measure the mRNA and protein expression of VEGFR-2, STAT-3, other proteins involved in the signaling pathway, hypoxia-inducible factor 1α(HIF-1α), and cyclin D1. The cellular radiosensitivity was determined by colony-forming assay and cell apoptosis and cell cycle distribution were evaluated by flow cytometry. Results For Calu-1 cells, there was no significant difference in the expression of VEGFR-2 mRNA and STAT-3 mRNA between the apatinib group and the control group (P>0.05); the apatinib group had significantly lower expression of HIF-1α mRNA and cyclin D1 mRNA than the control group (P<0.05); the apatinib+ S3I-201 group had significantly lower mRNA and phosphorylated protein expression of VEGFR-2, STAT-3, and related downstream target proteins than the control group (F=304.54, P<0.01; F=118.99, P<0.01, F=144.34, P<0.01; F=529.66, P<0.01); compared with the control group, the apatinib+ S3I-201 group and the apatinib group showed increases in apoptosis rate and proportion of cells in G2+ M phase, and the apatinib+ S3I-201 group had significantly greater increases than the apatinib group (F=72.37, P<0.01). Compared with Calu-1 cells, the radiosensitizing effect of apatinib on A549 cells was limited (SER[sensitizer enhancement ratio]=1.39). The radiosensitizing effect of apatinib+ S3I-201 on A549 cells was significantly higher than that of apatinib (SER: 1.72 vs. 1.39, P=0.000). Conclusions The inhibition of STAT-3 can enhance the radiosensitivity of NSCLC cells. When VEGFR-2 is inhibited by apatinib, activated STAT-3 regulates the expression of cyclin D1 directly or indirectly to affect the radiosensitivity of NSCLC cells. The inhibition of VEGFR-2 and STAT-3 has a good radiosensitizing effect on NSCLC cells. Key words: Protein express; Lung meoplasms cell line; Radiosensitivity

Efficacy and safety of anti-VEGF therapy in metastatic unresectable hepatocellular carcinoma: A meta-analysis.

e15632 Background:Conventional chemotherapy has limited role in metastatic unresectable hepatocellular carcinoma (HCC). Sorafenib is currently approved for metastatic unresectable HCC. We wanted to assess the efficacy and safety of other tyrosine kinase inhibitors (TKI) targeting vascular endothelial growth factor (VEGF) receptor such as brivanib, linifanib and regorafenib in metastatic HCC. Methods: We have searched electronic databases Pubmed, Google scholar to identify published trials using brivanib, linifanib and regorafenib in HCC. The outcomes evaluated were overall survival, time to disease progression (TTDP) and adverse effects. Hazard ratios (HR) with their respective 95% confidence intervals (CI) were then computed using the appropriate model for categorical variables. We used STATA 13.0 and Comprehensive Meta Analysis 2.0 software for all analyses. Results: We included seven randomized control studies. A combined analysis of these seven randomised control trials showed improved overall survival (OS) in VEGF-TKI group when compared to placebo HR - 0.79; (95% CI 0.62-1.00). However, there was no significant survival benefit of the newer VEGF receptor inhibitors when compared to sorafenib (HR - 1.05; 95% CI 0.95-1.17). The time to disease progression (TTDP) was significantly better in VEGF-TKI group as compared to placebo (HR - 0.61; 95% CI 0.39-0.97). However, there was no significant difference in TTDP between VEGF-TKI group and Sorafenib (HR - 0.88; 95% CI 0.66-1.16). Adverse effects were noted to be higher in VEGF-TKI group when compared to placebo (HR- 1.07; 95% CI 1.01-1.13). Conclusions: Treatment with TKI targeting VEGF receptor is associated with a significant improvement in OS and TTDP with tolerable side effect profile. Inhibiting the VEGF receptor pathway could lead to improved outcomes in HCC.

Efficacy of VEGF and VEGFR pathway inhibitors in the treatment of advanced gastric cancer

Anti-neovascularization is an important research direction in the current treatment of gastric cancer. The inhibitors of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGFR) are main research focus. At present, the inhibitors of the pathways of VEGF and VEGFR in the treatment of advanced gastric cancer include bevacizumab, ramucirumab, apatinib, regorafenib, sorafenib, et al. These drugs provide more possibilities for the treatment of advanced gastric cancer. Key words: Vascular endothelial growth factors; Receptors, vascular endothelial growth factor; Sto-mach neoplasms