VEGF-induced Angiogenesis Research Articles

PS1 FAD mutant M146V decreases VEGF-induced angiogenesis in brain endothelial cells.

Alzheimer's disease (AD) is a multifactorial and progressive neurodegenerative disease, and the most common form of dementia. Cerebrovascular abnormalities and reduced vascular density are observed in human AD brains. Vascular pathology is an early event that contributes to the progression of AD and it can be caused by impaired angiogenesis. Brain angiogenesis in response to toxic insults is a reparative function regulated by endothelial cells (ECs); impairment in this function would render the brain vulnerable to insults. One of the most potent angiogenic factors, Vascular Endothelial Growth factor (VEGF), promotes angiogenesis by binding VEGFR2 receptor, a type I transmembrane protein (TMP). Most type I TMP are proteolytically processed by γ-secretase, which has presenilin 1 (PS1) as a catalytic subunit. Mutations in PS1 cause Familial AD (FAD) and reduce the activity of γ-secretase. We hypothesize that PS1 FAD mutants decrease the VEGF-induced processing of VEGFR2 and brain angiogenesis. Targeting brain angiogenesis could have therapeutic value in AD. Primary cortical endothelial cells (pCECs) were isolated and cultured from brains of wild type (WT) and PS1 M146V knockin mice, a "humanized" FAD model having the same genotype as in human FAD patients. We performed the in vitro angiogenesis assays sprouting on beads, migration and tube formation using pCEC cultures. Processing of VEGFR2 was studied in VEGFR2-overexpressed HEK293 cells in presence or absence of VEGF-A and γ-secretase inhibitor (RO4929097) with western blotting. We found that VEGFR2 is processed by γ-secretase and that VEGF-induced sprouting, tube formation, migration and angiogenic complexes between VE-cadherin and Rok-α kinase in pCEC are decreased in the presence of γ-secretase inhibitor. We also found that pCEC expressing PS1 FAD mutant M146V do not sprout in response to VEGF as efficiently as WT cells. Our findings suggest that VEGFR2 is processed by γ-secretase and that γ-secretase promotes VEGF-induced angiogenic functions of brain ECs. Our data also show that PS1 FAD mutant decreases angiogenic functions of pCEC. Importantly the effects of PS1 FAD mutants occur in the absence of amyloid plaques and neurofibrillary tangles indicating that PS1 FAD mutants can affect angiogenesis independent of the neuropathological hallmarks of AD.

Clinical evidence for elevated levels of caveolin-1 in circulation of patients with diabetic foot ulcers.

Caveolin-1 directly interacts vascular endothelial growth factor receptor-2 (VEGFR2) and therefore prevents VEGF-induced angiogenesis. In addition, the production of nitric oxide (NO), which is effective in reducing ischemia in diabetic foot ulcers (DFU), is suppressed by caveolin-1 in endothelial cells. The present study was designed to investigate the change of caveolin-1 concentrations in DFU patients. A total of 150 participants were consecutively enrolled, including 40 DFU patients (DFU group), 40 diabetes patients without DFU (type 2 diabetes mellitus [T2DM] group), and 70 participants without diabetes (control group). Significant increased levels of plasma caveolin-1, accompanied with decreased concentration of plasma VEGF-A (vascular endothelial growth factor-A) and NO, were detected in DFU patients. Moreover, Pearson's correlation analysis revealed a negative correlation between plasma caveolin-1 and VEGF-A as well as NO levels in DFU patients. Furthermore, DFU patients had higher expression of caveolin-1 in the popliteal artery, compared to those in control and T2DM groups. Simultaneously, the amounts of eNOS (an enzyme responsible for the production of NO) and VEGFR2 were attenuated in the popliteal artery of DFU patients. Taken together, our study provided clinical evidence for the possible association of elevated caveolin-1 levels and the development of DFU. This may be induced by the suppressed VEGF-A/VEGFR2 and eNOS/NO signalling axis.

Recombinant thrombomodulin domain 1 rescues pathological angiogenesis by inhibition of HIF-1α-VEGF pathway.

Pathological angiogenesis (PA) contributes to various ocular diseases, including age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity, which are major causes of blindness over the world. Current treatments focus on anti-vascular endothelial growth factor (VEGF) therapy, but persistent avascular retina, recurrent intravitreal neovascularization, and general adverse effects are reported. We have previously found that recombinant thrombomodulin domain 1 (rTMD1) can suppress vascular inflammation. However, the function of rTMD1 in VEGF-induced PA remains unknown. In this study, we found that rTMD1 inhibited VEGF-induced angiogenesis in vitro. In an oxygen induced retinopathy (OIR) animal model, rTMD1 treatment significantly decreased retinal neovascularization but spared normal physiological vessel growth. Furthermore, loss of TMD1 significantly promoted PA in OIR. Meanwhile, hypoxia-inducible factor-1α, the transcription factor that upregulates VEGF, was suppressed after rTMD1 treatment. The levels of interleukin-6, and intercellular adhesion molecule-1 were also significantly suppressed. In conclusion, our results indicate that rTMD1 not only has dual effects to suppress PA and inflammation in OIR, but also can be a potential HIF-1α inhibitor for clinical use. These data bring forth the possibility of rTMD1 as a novel therapeutic agent for PA.

Sema3A accelerates bone formation during distraction osteogenesis in mice

ABSTRACT Distraction osteogenesis (DO) is a bone regeneration technique used to treat maxillofacial disorders, fracture nonunion, and large bone defects. It is well known for its amazing regenerative potential, but an extended consolidation period limits its clinical use. The interaction between the nervous system and bone regeneration has attracted great attention in recent years. Sema3A is a key axonal chemorepellent which has been proved to have bone-protective effects. In this article, we try to improve DO by local administration of Sema3A and explore the possible mechanisms. Forty wildtype, male, adult mice were divided into two groups after tibia osteotomy surgery. Sema3A or Saline was daily injected transcutaneous into the center of the distraction zone during the consolidation period. Micro-CT images were taken at 4, 6,8 and 10 weeks post-surgery; vascular density and biomechanical testing were performed at 10 weeks post-surgery. We also set up in vitro vessel growth assay to evaluate the effect of Sema3A on angiogenesis. Compared with the Saline group, Sema3A treatment significantly accelerated bone regeneration, improved angiogenesis and callus’ biomechanical strength. At 10 weeks post-surgery, compared with the Saline group, the BV/TV, BMD, TMD increased by about 23%, 22%, 18% respectively, vascular density increased by about 49% in the Sema3A group. Histological images and western-blot showed decreased expression of VEGF-A and increased expression of Ang-1 at 4 weeks post-surgery in the Sema3A group. In vitro, Sema3A suppressed VEGF-induced angiogenesis but had little effect on Ang-induced angiogenesis. Conclusion: Sema3A could accelerate bone regeneration and improve angiogenesis during DO.

The Critical Role of Growth Factors in Gastric Ulcer Healing: The Cellular and Molecular Mechanisms and Potential Clinical Implications.

In this article we review the cellular and molecular mechanisms of gastric ulcer healing. A gastric ulcer (GU) is a deep defect in the gastric wall penetrating through the entire mucosa and the muscularis mucosae. GU healing is a regeneration process that encompasses cell dedifferentiation, proliferation, migration, re-epithelialization, formation of granulation tissue, angiogenesis, vasculogenesis, interactions between various cells and the matrix, and tissue remodeling, all resulting in scar formation. All these events are controlled by cytokines and growth factors (e.g., EGF, TGFα, IGF-1, HGF, bFGF, TGFβ, NGF, VEGF, angiopoietins) and transcription factors activated by tissue injury. These growth factors bind to their receptors and trigger cell proliferation, migration, and survival pathways through Ras, MAPK, PI3K/Akt, PLC-γ, and Rho/Rac/actin signaling. The triggers for the activation of these growth factors are tissue injury and hypoxia. EGF, its receptor, IGF-1, HGF, and COX-2 are important for epithelial cell proliferation, migration, re-epithelialization, and gastric gland reconstruction. VEGF, angiopoietins, bFGF, and NGF are crucial for blood vessel regeneration in GU scars. The serum response factor (SRF) is essential for VEGF-induced angiogenesis, re-epithelialization, and blood vessel and muscle restoration. Local therapy with cDNA of human recombinant VEGF165 in combination with angiopoietin1, or with the NGF protein, dramatically accelerates GU healing and improves the quality of mucosal restoration within ulcer scars. The future directions for accelerating and improving healing include local gene and protein therapies with growth factors, their combinations, and the use of stem cells and tissue engineering.

The Regulatory Activity of GIPC1 on RhoA‐Mediated bFGF Angiogenic Functions

Introduction Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are the best characterized pro-angiogenic factors involved in tumor angiogenesis. Acquired resistance upon anti-VEGF therapy remains a serious disadvantage of current approaches. Here we show that the small GTPase RhoA, which is known to regulate VEGF-induced angiogenesis, also regulates bFGF-induced angiogenesis and we further explore the role of the scaffolding protein GAIP Interacting Protein C-terminus (GIPC1) as a regulator of RhoA activation and bFGF angiogenic outcomes. Methods We performed in vitro angiogenesis assays (cell migration, tube formation, spheroid sprouting) to assess the impact of pharmacological inhibition or knockdown of endothelial RhoA on bFGF-induced angiogenesis using human umbilical vein endothelial cells (HUVECs). RhoA and GEF Pull-down experiments, along with other biochemical assays were performed to identify the molecular mechanism(s) of bFGF-induced RhoA activation and regulatory function of GIPC1. In vivo, endothelial-specific inducible RhoA-deficient mice with a fluorescent reporter were used in a modified matrigel plug angiogenesis assay and in the ex vivo aortic ring assay. Results In vitro, bFGF-induced angiogenesis was abrogated by pharmacological RhoA inhibition or RhoA knockdown. In vivo, tamoxifen-induced endothelial RhoA-deficiency blocked bFGF-induced angiogenesis. Mechanistically, bFGF activates RhoA, through the RhoA-specific GEFs GEFH1, P115, LARG and PDZ-RhoGEF. Among the bFGF receptors, FGFR1 is predominantly expressed in HUVECs and FGFR1 knockdown abrogated bFGF-induced RhoA activation and angiogenesis. The scaffolding protein GIPC1 interacts with FGFR1 and has an inhibitory effect, since its downregulation induced RhoA activation as well as basal and bFGF-induced angiogenesis. Ongoing experiments are aiming to further delineate the FGFR1-GIPC1-RhoA relationship. Conclusions Our data suggest that GIPC1 is an important element of bFGF-induced angiogenesis through its regulatory effect on endothelial RhoA.

Interferon‐γ inhibits retinal neovascularization in a mouse model of ischemic retinopathy

Interferon‐γ (IFNG) is one of the key cytokines that regulates both innate and adaptive immune responses in the body. However, the role of IFNG in the regulation of vascularization, especially in the context of Vascular endothelial growth factor A (VEGFa)-induced angiogenesis is not clarified. Here, we report that IFNG shows potent anti-angiogenic potential against VEGFa-induced angiogenesis. IFNG significantly inhibited proliferation, migration, and tube formation of Human umbilical vein endothelial cells (HUVECs) both under basal and VEGFa-treated conditions. Intriguingly, Knockdown (KD) of STAT1 abolished the inhibitory effect of IFNG on VEGFa-induced angiogenic processes in HUVECs. Furthermore, IFNG exhibited potent anti-angiogenic efficacy in the mouse model of oxygen-induced retinopathy (OIR), an in vivo model for hypoxia-induced retinal neovascularization, without induction of functional side effects. Taken together, these results show that IFNG plays a crucial role in the regulation of VEGFa-dependent angiogenesis, suggesting its potential therapeutic applicability in neovascular diseases.

Zhuyu Annao decoction promotes angiogenesis in mice with cerebral hemorrhage by inhibiting the activity of PHD3.

Some traditional Chinese decoctions, such as Zhuyu Annao, exert favorable therapeutic effects on acute cerebral hemorrhage, hemorrhagic stroke, and other neurological diseases, but the underlying mechanism remains unclear. This study aimed to determine whether Zhuyu Annao decoction (ZYAND) protects the injured brain by promoting angiogenesis following intracerebral hemorrhage (ICH) and elucidate its specific mechanism. The effect of ZYAND on the nervous system of mice after ICH was explored through behavioral experiments, such as the Morris water maze and Rotarod tests, and its effects on oxidative stress were explored by detecting several oxidative stress markers, including malondialdehyde, nitric oxide, glutathione peroxidase, and superoxide dismutase. Real-time quantitative RT-PCR and WB were used to detect the effects of ZYAND on the levels of prolyl hydroxylase domain 3 (PHD3), hypoxia-inducible factor-1α (HIF-1α), and vascular endothelial growth factor (VEGF) in the brain tissues of mice. The effect of ZYAND on the NF-κB signaling pathway was detected using a luciferase reporter gene. A human umbilical cord vascular endothelial cell angiogenesis experiment was performed to determine whether ZYAND promotes angiogenesis. The Morris water maze test and other behavioral experiments verified that ZYAND improved the neurobehavior of mice after ICH. ZYAND activated the PHD3/HIF-1α signaling pathway, inhibiting the oxidative damage caused by ICH. In angiogenesis experiments, it was found that ZYAND promoted VEGF-induced angiogenesis by upregulating the expression of HIF-1α, and NF-κB signaling regulated the expression of HIF-1α by inhibiting PHD3. ZYAND exerts a reparative effect on brain tissue damaged after ICH through the NF-κB/ PHD3/HIF-1α/VEGF signaling axis.

Glycine-Conjugated Bile Acids Protect RPE Tight Junctions against Oxidative Stress and Inhibit Choroidal Endothelial Cell Angiogenesis In Vitro

We previously demonstrated that the bile acid taurocholic acid (TCA) inhibits features of age-related macular degeneration (AMD) in vitro. The purpose of this study was to determine if the glycine-conjugated bile acids glycocholic acid (GCA), glycodeoxycholic acid (GDCA), and glycoursodeoxycholic acid (GUDCA) can protect retinal pigment epithelial (RPE) cells against oxidative damage and inhibit vascular endothelial growth factor (VEGF)-induced angiogenesis in choroidal endothelial cells (CECs). Paraquat was used to induce oxidative stress and disrupt tight junctions in HRPEpiC primary human RPE cells. Tight junctions were assessed via transepithelial electrical resistance and ZO-1 immunofluorescence. GCA and GUDCA protected RPE tight junctions against oxidative damage at concentrations of 100–500 µM, and GDCA protected tight junctions at 10–500 µM. Angiogenesis was induced with VEGF in RF/6A macaque CECs and evaluated with cell proliferation, cell migration, and tube formation assays. GCA inhibited VEGF-induced CEC migration at 50–500 µM and tube formation at 10–500 µM. GUDCA inhibited VEGF-induced CEC migration at 100–500 µM and tube formation at 50–500 µM. GDCA had no effect on VEGF-induced angiogenesis. None of the three bile acids significantly inhibited VEGF-induced CEC proliferation. These results suggest glycine-conjugated bile acids may be protective against both atrophic and neovascular AMD.

Transcriptional Regulation of Thrombin-Induced Endothelial VEGF Induction and Proangiogenic Response

Thrombin, the ligand of the protease-activated receptor 1 (PAR1), is a well-known stimulator of proangiogenic responses in vascular endothelial cells (ECs), which are mediated through the induction of vascular endothelial growth factor (VEGF). However, the transcriptional events underlying this thrombin-induced VEGF induction and angiogenic response are less well understood at present. As reported here, we conducted detailed promotor activation and signal transduction pathway studies in human microvascular ECs, to decipher the transcription factors and the intracellular signaling events underlying the thrombin and PAR-1-induced endothelial VEGF induction. We found that c-FOS is a key transcription factor controlling thrombin-induced EC VEGF synthesis and angiogenesis. Upon the binding and internalization of its G-protein-coupled PAR-1 receptor, thrombin triggers ERK1/2 signaling and activation of the nuclear AP-1/c-FOS transcription factor complex, which then leads to VEGF transcription, extracellular secretion, and concomitant proangiogenic responses of ECs. In conclusion, exposure of human microvascular ECs to thrombin triggers signaling through the PAR-1–ERK1/2–AP-1/c-FOS axis to control VEGF gene transcription and VEGF-induced angiogenesis. These observations offer a greater understanding of endothelial responses to thromboinflammation, which may help to interpret the results of clinical trials tackling the conditions associated with endothelial injury and thrombosis.

Effect of dual PPAR-α/γ agonist saroglitazar on diabetic retinopathy and oxygen-induced retinopathy

Diabetic retinopathy is a serious complication of diabetes, marked by retinal vascular damage, inflammation, and angiogenesis. This study's objective was to assess the potential benefits of saroglitazar, a peroxisome proliferator-activated receptor-alpha/gamma (PPAR-α/γ) agonist in diabetic retinopathy. Diabetic retinopathy was induced by streptozotocin in Sprague Dawley rats. The effect of saroglitazar was also assessed in the oxygen-induced retinopathy model in newborn rats and VEGF-induced angiogenesis in the chick chorioallantoic membrane (CAM) assay.Treatment of saroglitazar (1 and 4 mg/kg, oral) for 12 weeks significantly ameliorated retinal vascular leakage and leukostasis in the diabetic rats. Saroglitazar decreased oxidative stress, VEGF receptor signalling, NF-κBp65, and ICAM-1 in the retina of diabetic rats. The beneficial effects of saroglitazar (1 and 4 mg/kg, oral) were also observed on the neovascularization in oxygen-induced retinopathy in newborn rats. Saroglitazar also reduced VEGF-induced angiogenesis in CAM assay.This study reveals that saroglitazar has the potential to prevent the progression of retinopathy in diabetic patients.

Serum-Derived Exosomes from Patients with Coronary Artery Disease Induce Endothelial Injury and Inflammation in Human Umbilical Vein Endothelial Cells.

Endothelial injury and inflammation have been found to be essential in the pathogenesis of coronary artery disease (CAD). Circulating exosomes are of great value as novel biomarkers for CAD. However, the role of circulating exosomes in the pathogenesis of CAD remains unclear. Thus, in this study, we aimed to examine whether circulating exosomes from CAD are involved in the endothelial injury and inflammation. The serum-derived exosomes were isolated from CAD and controls using an ExoQuick reagent, and these were then quantified by measuring the protein levels using BCA methods. The uptake of exosomes by human umbilical vein endothelial cells (HUVECs) was observed by laser scanning microscope and analyzed via flow cytometry. Then, HUVECs were treated with vehicle, exosomes from CAD (CAD-exo), and controls (ctrl-exo) in the absence and presence of vascular endothelial growth factor (VEGF). Cell viability, migration, and angiogenesis were evaluated using CCK-8 assay, scratch assay, and tube formation assay. Inflammatory factors including IL-1β, IL-6, TNF-α, ICAM-1, and VCAM-1 levels were detected via qPCR. As per our findings, no significant differences were noted in uptake of ctrl-exo and CAD-exo by HUVECs. CAD-exo suppressed cell viability in a dose-dependent manner. Compared with ctrl-exo, CAD-exo-treated HUVECs significantly suppressed migration and angiogenesis. However, CAD-exo had a stronger inhibitory effect on VEGF-induced migration and angiogenesis compared with ctrl-exo. Moreover, IL-1β, TNF-α, and ICAM-1 were determined to be significantly upregulated in HUVECs treated with CAD-exo, but IL-6 and VCAM-1 expressions were not affected. Overall, our results suggest that CAD-exo are involved in endothelial injury and inflammation, which may, in turn, cause endothelial dysfunction and potentially promote the development of CAD.

Knockout of vasohibin-2 reduces tubulin carboxypeptidase activity and increases paclitaxel sensitivity in ovarian cancer.

Vasohibin‐1 (VASH1) is a VEGF‐inducible endothelium‐derived angiogenesis inhibitor, and vasohibin‐2 (VASH2), its homolog, exhibits proangiogenic activity. VASH2 is expressed by various cancer cells and accelerates tumor angiogenesis and progression. VASH2 was recently shown to exhibit tubulin carboxypeptidase (TCP) activity related to microtubule functions. Paclitaxel (PTX), an effective chemotherapeutic agent that is widely used to treat ovarian cancer, inhibits microtubule depolymerization and may interact with VASH2. We herein established several VASH2 knockout ovarian cancer cell lines using the CRISPR/Cas9 genome editing system to examine the intracellular tubulin detyrosination status and PTX chemosensitivity. The knockout of VASH2 did not affect the proliferation or sphere‐forming activity of ovarian cancer cells in vitro. A Western blot analysis of VASH2 knockout cells revealed the weak expression of detyrosinated tubulin and upregulated expression of cyclin B1. The knockout of VASH2 significantly increased chemosensitivity to PTX, but not to cisplatin in ovarian cancer cell lines. The knockout of VASH2 reduced TCP activity and increased cyclin B1 expression, resulting in increased PTX chemosensitivity in ovarian cancer cells. The inhibition of angiogenesis and regulation of microtubule activity may be achieved in ovarian cancer treatment strategies targeting VASH2.

Obesity alters ovarian folliculogenesis through disrupted angiogenesis from increased IL-10 production

ObjectiveObesity has been reported to have a modulatory effect on the ovulatory functions of patients with polycystic ovary syndrome. The role of adipokines in this obesity-associated ovulatory disturbance has not been extensively explored. In this study, the relationships between obesity, adipokine production from visceral fat, and ovarian folliculogenesis were explored in a mice model of induced obesity. MethodsObesity was induced in female C57BL/6 mice fed ad libitum with high-fat feed and fructose water for 4 weeks. Follicular developments in the ovaries were assessed by histopathology in these diet-induced obese mice. Changes in adipokine expression in the peri-ovarian adipose tissues were screened with an adipokine array. The adipokine with the most significant increase over time was identified. The functions of the adipokine in angiogenic processes were evaluated in a cell model of endothelial proliferation. The in vivo effects of neutralizing this adipokine using specific antibodies were assessed in the same obesity model. ResultsA high-fat and fructose diet induced an accumulation of early ovarian follicles and a reduction in mature follicles and corpus lutea. The number of microvessels in the early follicles also decreased. The adipokine protein array of the peri-ovarian adipose tissues identified a progressive increase in IL-10 expression with the duration of the obesogenic diet. In vitro experiments in the endothelial cell model confirmed IL-10 as a disrupter of VEGF-induced angiogenesis. Administration of anti-IL-10 antibodies prevented the histopathological changes induced by the obesogenic diet and further highlighted the role of IL-10 in disrupting folliculogenesis. ConclusionsObesity may disrupt normal folliculogenesis through increased production of IL-10 in visceral fats. This relationship may help clarify the reported association between obesity and ovulatory dysfunction, which has been found in patients with polycystic ovary syndrome. However, the duration of this study was short, which limited conclusions on the long-term reproductive outcomes.

A 60% Edible Ethanolic Extract of Ulmus davidiana Inhibits Vascular Endothelial Growth Factor-Induced Angiogenesis.

As abnormal angiogenesis is associated with exacerbation of various diseases, precise control over angiogenesis is imperative. Vascular endothelial growth factor (VEGF), the most well-known angiogenic factor, binds to VEGF receptor (VEGFR), activates various signaling pathways, and mediates angiogenesis. Therefore, blocking the VEGF-induced angiogenic response-related signaling pathways may alleviate various disease symptoms through inhibition of angiogenesis. Ulmus davidiana is a safe natural product that has been traditionally consumed, but its effects on endothelial cells (ECs) and the underlying mechanism of action are unclear. In the present study, we focused on the effect of a 60% edible ethanolic extract of U. davidiana (U60E) on angiogenesis. U60E inhibited the VEGF-mediated proliferation, tube formation, and migration ability of ECs. Mechanistically, U60E inhibited endothelial nitric oxide synthase activation and nitric oxide production by blocking the protein kinase B signaling pathway activated by VEGF and consequently inhibiting proliferation, tube formation, and migration of ECs. These results suggest that U60E could be a potential and safe therapeutic agent capable of suppressing proangiogenic diseases by inhibiting VEGF-induced angiogenesis.

Abstract PR011: Selective inhibition of VEGF binding to VEGFR2 promotes an immune stimulatory microenvironment in murine models of breast cancer

Abstract Vascular endothelial growth factor-A (VEGF) is the dominant angiogenic factor that promotes tumor neovascularization, making it a critical target for cancer therapy. VEGF binds and activates VEGF receptor 1 (VEGFR1) and VEGFR2, with VEGFR2 being the principal receptor mediating VEGF-induced angiogenesis while VEGFR1 has a negative regulatory effect on this process. Previously, we found that selective inhibition of VEGF binding to VEGFR2 with a fully human monoclonal antibody (r84) or its mouse chimeric counterpart (mcr84) is sufficient for effective control of tumor growth in preclinical models of breast cancer. However, accumulating evidence indicates that the effect of blocking VEGF activity in solid tumors extends beyond inhibition of angiogenesis. Concordantly, we have shown that VEGF blockade regulates immune cell trafficking across the endothelium by increasing the expression of adhesion molecules while decreasing FasL expression on tumor vasculature. In addition, specifically blocking VEGF binding to VEGFR2 promotes an immune stimulatory microenvironment by enhancing activation of CD8+ cytotoxic T cells as evidenced by elevated secretion of Granzyme B and IFN-γ. In addition, VEGF blockade also reduces FoxP3+ regulatory T cell infiltration in multiple murine models of cancer. We and others have shown that immune cells express receptors for VEGF. Our data indicate that VEGFR2 expression is elevated on myeloid cells selectively in tumor-bearing animals. Consistent with VEGFR2 expression, treatment with mcr84 results in a reduction in macrophage/myeloid cell infiltration into murine breast tumors. In conclusion, our results enhance understanding of the function of VEGFR2 signaling on myeloid cells and suggest that selective inhibition of VEGF from binding VEGFR2 facilitates immune activation landscape in breast cancer models, which might enhance the efficacy of immune checkpoint blockade. This abstract is also being presented as PO045. Citation Format: Yuqing Zhang, Huocong Huang, Noah Sorrelle, Rolf Brekken. Selective inhibition of VEGF binding to VEGFR2 promotes an immune stimulatory microenvironment in murine models of breast cancer [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PR011.

Effect of Babao Dan on angiogenesis of gastric cancer in vitro by regulating VEGFA/VEGFR2 signaling pathway.

BackgroundTo further elucidate the anti-angiogenesis effect of Babao Dan (BBD) in vitro, gastric cancer (GC) cells and human umbilical vein endothelial cells (HUVECs) were used to evaluate the regulation role of BBD by vascular endothelial growth factor A (VEGFA)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathway.MethodsAfter induced by VEGFA, GC cells (AGS, MGC80-3 and BGC823) were treated by different concentrations of BBD and then were detected cell viability, migration and VEGFA level. And the anti-angiogenesis effect of BBD was evaluated with HUVECs. To furtherly mimic the tumor microenvironment of angiogenesis, VEGFA as an inducer (10 ng/mL) was used to trigger a cascade of angiogenesis of HUVECs in vitro.ResultsThe viability and migration of GC cells with VEGFA-induced or non-induced and VEGFA levels in GC cells were significantly inhibited by BBD with concentration-dependent manner (P<0.01). BBD significantly inhibited the HUVECs viability with concentration-dependent manner (P<0.01), which was consistent with the inhibitory action on augmentation of cell viability induced by VEGFA (P<0.01). BBD exhibited the similar inhibitory trend on cyto behavioral variability such as wound repairing (P<0.05), migration (P<0.01) and tube formation (P<0.01) and activation effect on cell apoptosis rate (P<0.01) with VEGFA-induced or non-induced. Moreover, BBD notably regulated the levels of VEGFA, VEGFR2, matrix metalloprotein 2 (MMP2) and matrix metalloprotein 9 (MMP9) of HUVECs on present or absent of VEGFA with dose-dependent manner.ConclusionsBBD inhibited GC growth against VEGFA-induced angiogenesis of HUVECs by VEGFA/VEGFR2 signaling pathway in vitro.

EVL regulates VEGF receptor-2 internalization and signaling in developmental angiogenesis.

Endothelial tip cells are essential for VEGF‐induced angiogenesis, but underlying mechanisms are elusive. The Ena/VASP protein family, consisting of EVL, VASP, and Mena, plays a pivotal role in axon guidance. Given that axonal growth cones and endothelial tip cells share many common features, from the morphological to the molecular level, we investigated the role of Ena/VASP proteins in angiogenesis. EVL and VASP, but not Mena, are expressed in endothelial cells of the postnatal mouse retina. Global deletion of EVL (but not VASP) compromises the radial sprouting of the vascular plexus in mice. Similarly, endothelial‐specific EVL deletion compromises the radial sprouting of the vascular plexus and reduces the endothelial tip cell density and filopodia formation. Gene sets involved in blood vessel development and angiogenesis are down‐regulated in EVL‐deficient P5‐retinal endothelial cells. Consistently, EVL deletion impairs VEGF‐induced endothelial cell proliferation and sprouting, and reduces the internalization and phosphorylation of VEGF receptor 2 and its downstream signaling via the MAPK/ERK pathway. Together, we show that endothelial EVL regulates sprouting angiogenesis via VEGF receptor‐2 internalization and signaling.

Anlotinib suppresses metastasis and multidrug resistance via dual blockade of MET/ABCB1 in colorectal carcinoma cells.

Anlotinib, a highly selective multi-targeted tyrosine kinase inhibitor (TKI) has therapeutic effects on non-small-cell lung cancer (NSCLC). In this study, the anti-tumor activity and molecular mechanism of anlotinib in metastatic colorectal cancer (mCRC) was explored. The anti-angiogenesis, anti-metastasis, anti-proliferative, and anti-multidrug resistance efficacy of anlotinib were analyzed by using in vitro and in vivo models of human CRC cells. The results indicated that anlotinib boosted chemo-sensitivity of CRC cells, and restrained its proliferation. Besides the suppression of the MET signaling pathway, anlotinib also inhibited invasion and migration of CRC cells. Furthermore, anlotinib prevented VEGF-induced angiogenesis, N-cadherin (CDH2)-induced cell migration, and reversed ATP-binding cassette subfamily B member 1 (ABCB1) -mediated CRC multidrug resistance in CRC. The CRC liver metastasis and subcutaneously implanted xenograft model testified that anlotinib could inhibit proliferation and liver metastasis in CRC cells. Such an observation suggested that a combination of anlotinib with anti-cancer drugs could attenuate angiogenesis, metastasis, proliferative, and multidrug resistance, which constitutes a novel treatment strategy for CRC patients with metastasis.

Xanthorrhizol Suppresses Vascular Endothelial Growth Factor-Induced Angiogenesis by Modulating Akt/eNOS Signaling and the NF-[Formula: see text]B-Dependent Expression of Cell Adhesion Molecules.

Angiogenesis plays a crucial role in tumor growth and metastasis. Vascular endothelial growth factor (VEGF)-stimulated endothelial cell proliferation and migration are critical steps in tumor angiogenesis. Here, we investigated the anti-angiogenic activity of xanthorrhizol, a sesquiterpenoid isolated from the Indonesian medicinal plant Curcuma xanthorrhiza. Xanthorrhizol at noncytotoxic concentrations inhibited the proliferation, migration, and formation of capillary-like tubes in VEGF-treated human umbilical vein endothelial cells (HUVECs). Xanthorrhizol inhibited the phosphorylation of Akt and endothelial nitric oxide synthase (eNOS) and the expression of vascular cell adhesion molecule (VCAM)-1 and E-selectin in VEGF-treated HUVECs. The expression and transcriptional activity of NF-[Formula: see text]B were downregulated by xanthorrhizol in VEGF-treated HUVECs. Furthermore, xanthorrhizol significantly inhibited VEGF-induced angiogenesis in the chorioallantoic membrane of fertilized eggs and Matrigel plugs subcutaneously injected into mice. Xanthorrhizol inhibited tumor volume and tumor-derived angiogenesis in mice inoculated with breast cancer cells. The in vitro and in vivo anti-angiogenic activities of xanthorrhizol were as potent as those of curcumin, a well-known anticancer agent derived from C. longa. Taken together, xanthorrhizol inhibits VEGF-induced angiogenesis of endothelial cells by blocking the activation of the PI3K/Akt/eNOS axis and subsequent upregulation of adhesion molecules induced by the transcriptional activation of NF-[Formula: see text]B. Xanthorrhizol is a promising anti-angiogenic agent and can serve as a beneficial agent to enhance anticancer treatments.