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Abstract Background Angiogenesis, or the growth of new vasculature from existing blood vessels, is widely considered a primary hallmark of cancer progression. When a tumor is small, diffusion is sufficient to receive essential nutrients; however, as the tumor grows, a vascular supply is needed to deliver oxygen and nutrients into the increasing mass. Several anti-angiogenic cancer therapies target VEGF and the receptor VEGFR-2, which are major promoters of blood vessel development. Unfortunately, many of these cancer treatments fail to completely stop angiogenesis in the tumor microenvironment (TME). Since these therapies focus on the biochemical activation of VEGFR-2 via VEGF ligand binding, we propose that mechanical cues, particularly those found in the TME, may be a source of VEGFR-2 activation that promotes growth of blood vessel networks even in the presence of VEGF and VEGFR-2 inhibitors. Results In this paper, we analyzed phosphorylation patterns of VEGFR-2, particularly at Y1054/Y1059 and Y1214, stimulated via either VEGF or biomechanical stimulation in the form of tensile strains. Our results show prolonged and enhanced activation at both Y1054/Y1059 and Y1214 residues when endothelial cells were stimulated with strain, VEGF, or a combination of both. We also analyzed Src expression, which is downstream of VEGFR-2 and can be activated through strain or the presence of VEGF. Finally, we used fibrin gels and microfluidic devices as 3D microtissue models to simulate the TME. We determined that regions of mechanical strain promoted increased vessel growth, even with VEGFR-2 inhibition through SU5416. Conclusions Overall, understanding both the effects that biomechanical and biochemical stimuli have on VEGFR-2 activation and angiogenesis is an important factor in developing effective anti-angiogenic therapies. This paper shows that VEGFR-2 can be mechanically activated through strain, which likely contributes to increased angiogenesis in the TME. These proof-of-concept studies show that small molecular inhibitors of VEGFR-2 do not fully prevent angiogenesis in 3D TME models when mechanical strains are introduced.

To investigate the effect of Taohong Siwu decoction on the expression of vascular endothelial growth factor(VEGF), vascular endothelial growth factor receptor 2 (VEGFR-2), protein kinase B (Akt) gene and protein in brain microvascularendothelial cells (rBMECs) of rats with oxygen glucose deprivation (OGD) and its mechanism. The rBMECs were cultured andrandomly divided into normal group, model group, Taohong Siwu decoction (0.4 mg/m L ) group and Taohong Siwu decoction (0.8mg/mL) group. In addition to the normal group, the other three groups used oxygen glucose deprivation experiment to construct OGD injury model. Taohong Siwu decoction group was added with Taohong Siwu decoction at a concentration of 0.4 mg/mL and 0.8 mg/mL 1hbefore modeling, while the normal group and the model group were added with the same volume of normal saline. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting were used to detect the expression of VEGF, VEGFR-2 and Akt genes and proteins. Compared with the normal group, the apoptosis rate of the model group was significantly increased(P<0.05). Compared with the model group, the Taohong Siwu decoction (0.4 mg/mL) group and Taohong Siwu decoction (0.8 mg/mL) group decreased, and the Taohong Siwu decoction (0.8 mg/mL) group was the most significant(P<0.05). Compared with the normal group, the relative mRNAand protein expression levels of Akt, VEGFR-2 and VEGF in rBMECs of the model group were significantly increased (P<0.05). Com-pared with the model group, the Taohong Siwu decoction (0.4 mg/mL) group and Taohong Siwu decoction (0.8 mg/mL) group were significantly decreased, and the Taohong Siwu decoction (0.8 mg/mL) group was the most significant. Taohong Siwu decoction may inhibit the apoptosis of endothelial cells and maintain the integrity of endothelial cells by reducing the expression levels of VEGF, VEGFR-2 and Akt genes and proteins in rBMECs under OGD conditions, which may be one of the mechanisms of Taohong Siwu Decoction on brain protection. [ABSTRACT FROM AUTHOR]

Background: Angiogenesis, or the growth of new vasculature from existing blood vessels, is widely considered a primary hallmark of cancer progression. When a tumor is small, diffusion is sufficient to receive essential nutrients; however, as the tumor grows, a vascular supply is needed to deliver oxygen and nutrients into the increasing mass. Several anti-angiogenic cancer therapies target VEGF and the receptor VEGFR-2, which are major promoters of blood vessel development. Unfortunately, many of these cancer treatments fail to completely stop angiogenesis in the tumor microenvironment (TME). Since these therapies focus on the biochemical activation of VEGFR-2 via VEGF ligand binding, we propose that mechanical cues, particularly those found in the TME, may be a source of VEGFR-2 activation that promotes growth of blood vessel networks even in the presence of VEGF and VEGFR-2 inhibitors. Results: In this paper, we analyzed phosphorylation patterns of VEGFR-2, particularly at Y1054/Y1059 and Y1214, stimulated via either VEGF or biomechanical stimulation in the form of tensile strains. Our results show prolonged and enhanced activation at both Y1054/Y1059 and Y1214 residues when endothelial cells were stimulated with strain, VEGF, or a combination of both. We also analyzed Src expression, which is downstream of VEGFR-2 and can be activated through strain or the presence of VEGF. Finally, we used fibrin gels and microfluidic devices as 3D microtissue models to simulate the TME. We determined that regions of mechanical strain promoted increased vessel growth, even with VEGFR-2 inhibition through SU5416. Conclusions: Overall, understanding both the effects that biomechanical and biochemical stimuli have on VEGFR-2 activation and angiogenesis is an important factor in developing effective anti-angiogenic therapies. This paper shows that VEGFR-2 can be mechanically activated through strain, which likely contributes to increased angiogenesis in the TME. These proof-of-concept studies show that small molecular inhibitors of VEGFR-2 do not fully prevent angiogenesis in 3D TME models when mechanical strains are introduced. [ABSTRACT FROM AUTHOR]

Haemangiomas (HAs) are prevalent vascular endothelial cell tumours. With respect to the possible involvement of HIF‐1α in HAs, we have explored its role in haemangioma endothelial cell (HemEC) proliferation and apoptosis. shRNA HIF‐1α and pcDNA3.1 HIF‐α were manipulated into HemECs. HIF‐α, VEGF, and VEGFR‐2 mRNA and protein levels were assessed by qRT‐PCR and Western blotting. Cell proliferation and viability, cell cycle and apoptosis, migration and invasion, and ability to form tubular structures were assessed by colony formation assay, CCK‐8, flow cytometry, Transwell assay, and tube formation assay. Cell cycle‐related protein levels, and VEGF and VEGFR‐2 protein interaction were detected by Western blot and immunoprecipitation assays. An Haemangioma nude mouse model was established by subcutaneous injection of HemECs. Ki67 expression was determined by immunohistochemical staining. HIF‐1α silencing suppressed HemEC neoplastic behaviour and promoted apoptosis. HIF‐1α facilitated VEGF/VEGFR‐2 expression and the VEGF had interacted with VEGFR‐2 at protein ‐ protein level. HIF‐1α silencing arrested HemECs at G0/G1 phase, diminished Cyclin D1 protein level, and elevated p53 protein level. VEGF overexpression partially abrogated the effects of HIF‐1α knockdown on inhibiting HemEC malignant behaviours. Inhibiting HIF‐1α in nude mice with HAs repressed tumour growth and Ki67‐positive cells. Briefly, HIF‐1α regulated HemEC cell cycle through VEGF/VEGFR‐2, thus promoting cell proliferation and inhibiting apoptosis. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factors (VEGFs) are specific cytokines involved in angiogenesis and do so via binding to vascular endothelial growth factor receptors (VEGFRs), a type of receptor tyrosine kinase. VEGFs are reported to facilitate angiogenesis in physiological (embryogenesis) and pathological (tumor) conditions. The overexpression of VEGFs and consequently VEGFRs is reported in tumorigenic conditions. Several VEGFR inhibitors currently used as anticancer drugs to prevent angiogenesis are sunitinib, sorafenib, etc. To identify new potential candidates as VEGFR inhibitors, a classification study using a large and diverse dataset of VEGFR inhibitors from the BindingDB database has been conducted. The KNIME platform was used to calculate molecular and fingerprint‐based descriptors and several classification algorithms viz. linear regression (LR), k‐nearest neighbor (kNN), decision tree (DT), random forest (RF), and gradient boosted tree (GBT) were employed to build the classification model. The model performance was evaluated by accuracy, precision, recall, and F1 score of the test set. The best LR, kNN, DT, RF, and GBT classifiers had the F1 score of 0.81, 0.87, 0.82, 0.87, and 0.87, respectively. The assorted 5120 VEGFR inhibitors were clustered into 10 subsets, and the structural features of each subset were assessed along with the identification of significant fragments in active and inactive compounds. The automated classifier model developed using the KNIME platform could serve as an important platform for screening and designing molecules as VEGFR inhibitors. [ABSTRACT FROM AUTHOR]

Objective: Angiogenesis is indeed a vital process in the progression of carcinomas, including that of larynx. Therefore, this study (AngLaC) aimed to identify candidate angiogenesis‐related biomarkers in laryngeal carcinoma patients. Study Design: Prospective controlled cohort study. Setting: Tertiary referral center. Methods: In silico analyses of angiogenesis‐related genes in laryngeal carcinoma were performed to determine candidate biomarkers. Serum levels of candidate biomarkers were determined via enzyme‐linked immunosorbent assay in laryngeal carcinoma patients as well as in an age and gender‐matched control group. The associations of the biomarkers with clinical parameters were investigated. Results: The study included 60 laryngeal carcinoma patients and 20 healthy controls. The serum levels of osteopontin, IGFBP‐3, VEGF, sVEGFR‐1, and VEGFR‐2 were significantly higher in the patient group (p <.001, p ≤.001, p <.001, p <.01, p <.01, respectively). High osteopontin and sVEGFR‐1 levels were associated with locoregional‐recurrence (p =.024, p =.016, respectively). IGFBP‐3 had the highest diagnostic sensitivity (81.4%) and specificity (80%) among the molecules that were investigated (p <.001). High sVEGFR‐1 and low VEGFR‐2 levels were associated with poor overall‐survival (p =.037, p =.027, respectively). High osteopontin and sVEGFR‐1 levels were associated with poor disease‐specific survival rates (p =.035, p =.018, respectively). Conclusion: High serum levels of sVEGFR‐1 and osteopontin as well as low serum levels of VEGFR‐2 proved to be poor prognostic in terms of survival in laryngeal carcinoma. VEGF, sVEGFR1, VEGFR2, IGFBP‐3, and osteopontin levels were found to be significantly increased in larynx cancer patients compared to the normal population. Further studies on osteopontin and sVEGFR‐1 are required in order to determine their associations with recurrence. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to obtain an insight into the role of the vascular endothelial growth factor (VEGF) in pregnancy-associated mammary epithelial development and angiogenesis. However, we examined the primary VEGF receptor (VEGFR-2) in the mouse mammary cycle. Materials and Methods: The virgin (1012 weeks), days 10 and 18 of pregnancy (P-10 and P-18), days 0, 5, 10, and 20 of lactation (L-0, L-5, L-10, and L-20), and days 5 and 10 of post-weaning (W-5 and W-10) stage were all used in this study. Immunohistochemistry and Western blotting were carried out on mammary tissues taken from three mice at each stage. Results: VEGFR-2 was detected immunohistochemically in the cytoplasm of mammary epithelial and endothelial cells. Immunostaining for VEGFR-2 was consistently positive in mammary endothelial cells across all stages, whereas staining intensity in epithelial cells varied across the mammary cycle. Additionally, immunoblot analysis indicated a 220 kDa unique band of VEGFR-2 protein at all stages of the mammary cycle, with the maximum expression reported toward the end of pregnancy and gradually decreasing toward the end of lactation. Conclusion: In conclusion, the presence of VEGFR-2 in the mammary epithelium in addition to the endothelium suggests that VEGF plays an autocrine and paracrine role in the development, proliferation, and differentiation of the mammary epithelium during pregnancy. [J Adv Vet Anim Res 2021; 8(4.000): 581-588]

Although the enteric nervous system (ENS) functions largely autonomously as part of the peripheral nervous system (PNS), it is connected to the central nervous system (CNS) via the gut–brain axis. In many neurodegenerative diseases, pathological changes occur in addition to gastrointestinal symptoms, such as alpha-synuclein aggregates in Parkinson's disease, which are found early in the ENS. In both the CNS and PNS, vascular endothelial growth factor (VEGF) mediates neuroprotective and neuroregenerative effects. Since the ENS with its close connection to the microbiome and the immune system is discussed as the origin of neurodegenerative diseases, it is necessary to investigate the possibly positive effects of VEGF on enteric neurons. Using laser microdissection and subsequent quantitative RT-PCR as well as immunohistochemistry, for the first time we were able to detect and localize VEGF receptor expression in rat myenteric neurons of different ages. Furthermore, we demonstrate direct neuroprotective effects of VEGF in the ENS in cell cultures. Thus, our results suggest a promising approach regarding neuroprotection, as the use of VEGF (may) prevent neuronal damage in the ENS. [ABSTRACT FROM AUTHOR]

Aim – to study the features of VEGF, VEGFR-2 and CD31, CD105 immunohistochemical expression in the cerebral cortex in diabetes mellitus type 2. Materials and methods. Pathomorphological and immunohistochemical studies of the brain tissue section material were performed in 3 groups of observations: group I – control without DM and cerebrovascular pathology, group II – died with dyscirculatory-ischemic encephalopathy (DIE), group III – died with DM type 2. Results. Increased expression of VEGF and VEGFR-2 was found both in dyscirculatory-ischemic encephalopathy and in patients with diabetes mellitus type 2 (VEGF in the control group – 0.337 (0.232; 0.617) %, in the group with DIE – 0.713 (0.438); 1.304) %, in the group with diabetes mellitus type 2 – 1.003 (0.699; 1.631) %; VEGFR-2 in the group of control – 0.916 (0.550; 1.56) %, in the group with DIE – 1,238 (0.76; 1.61) %, in the group with DM type 2 – 1.15 (0.58; 1.784) %. There is direct correlation between the level of expression of CD105 and VEGFR-2: r = 0.31 for diabetes type 2. The distribution density of microvessels significantly increases in the group with DM type 2. Significant increase in expression of CD105 in the group with DM type 2 (0.434 (0.265; 0.741) %) was found, compared with the group of control (0.346 (0.263; 0.46) %). There are direct correlations between CD31 and CD105 expression in DIE (r = 0,41) and in the group with DM type 2 (r = 0,39, P < 0.05). Conclusions. Angiogenesis is activated in the cerebral cortex in diabetes type 2, which may be due to the activation of the transcription factor HIF-1a.

Objective: The objective of this study was to obtain an insight into the role of the vascular endothelial growth factor (VEGF) in pregnancy-associated mammary epithelial development and angiogenesis. However, we examined the primary VEGF receptor (VEGFR-2) in the mouse mammary cycle. Materials and Methods: The virgin (10-12 weeks), days 10 and 18 of pregnancy (P-10 and P-18), days 0, 5, 10, and 20 of lactation (L-0, L-5, L-10, and L-20), and days 5 and 10 of post-weaning (W-5 and W-10) stage were all used in this study. Immunohistochemistry and Western blotting were carried out on mammary tissues taken from three mice at each stage. Results: VEGFR-2 was detected immunohistochemically in the cytoplasm of mammary epithelial and endothelial cells. Immunostaining for VEGFR-2 was consistently positive in mammary endothelial cells across all stages, whereas staining intensity in epithelial cells varied across the mammary cycle. Additionally, immunoblot analysis indicated a 220 kDa unique band of VEGFR-2 protein at all stages of the mammary cycle, with the maximum expression reported toward the end of pregnancy and gradually decreasing toward the end of lactation. Conclusion: In conclusion, the presence of VEGFR-2 in the mammary epithelium in addition to the endothelium suggests that VEGF plays an autocrine and paracrine role in the development, proliferation, and differentiation of the mammary epithelium during pregnancy. [ABSTRACT FROM AUTHOR]

Background: Patients with congenital diaphragmatic hernia (CDH) have a short postnatal period of ventilatory stability called the honeymoon period, after which changes in pulmonary vascular reactivity result in pulmonary hypertension. However, the mechanisms involved are still unknown. The aim of this study was to evaluate mechanical ventilation's effect in the honeymoon period on VEGF, VEGFR-1/2 and eNOS expression on experimental CDH in rats.Materials and Methods: Neonates whose mothers were not exposed to nitrofen formed the control groups (C) and neonates with left-sided defects formed the CDH groups (CDH). Both were subdivided into non-ventilated and ventilated for 30, 60, and 90 min (n = 7 each). The left lungs (n = 4) were evaluated by immunohistochemistry of the pulmonary vasculature (media wall thickness), VEGF, VEGFR-1/2 and eNOS. Western blotting (n = 3) was performed to quantify the expression of VEGF, VEGFR-1/2 and eNOS.Results: CDH had lower biometric parameters than C. Regarding the pulmonary vasculature, C showed a reduction in media wall thickness with ventilation, while CDH presented reduction with 30 min and an increase with the progression of the ventilatory time (honeymoon period). CDH and C groups showed different patterns of VEGF, VEGFR-1/2 and eNOS expressions. The receptors and eNOS findings were significant by immunohistochemistry but not by western blotting, while VEGF was significant by western blotting but not by immunohistochemistry.Conclusion: VEGF, its receptors and eNOS were altered in CDH after mechanical ventilation. These results suggest that the VEGF-NO pathway plays an important role in the honeymoon period of experimental CDH.

The vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) play crucial roles in vasculogenesis and angiogenesis. Angiogenesis is an important mechanism in many physiological and pathological processes, and is involved in endothelial cell proliferation, migration, and survival, then leads to further tubulogenesis, and finally promotes formation of vessels. This series of signaling cascade pathways are precisely mediated by VEGF/VEGFR-2 system. The VEGF binding to the IgD2 and IgD3 of VEGFR-2 induces the dimerization of the receptor, subsequently the activation and trans-autophosphorylation of the tyrosine kinase, and then the initiation of the intracellular signaling cascades. Finally the VEGF-activated VEGFR-2 stimulates and mediates variety of signaling transduction, biological responses, and pathological processes in angiogenesis. Several crucial phosphorylated sites Tyr801, Try951, Try1175, and Try1214 in the VEGFR-2 intracellular domains mediate several key signaling processes including PLCγ-PKC, TSAd-Src-PI3K-Akt, SHB-FAK-paxillin, SHB-PI3K-Akt, and NCK-p38-MAPKAPK2/3 pathways. Based on the molecular structure and signaling pathways of VEGFR-2, the strategy of the VEGFR-2-targeted therapy should be considered to employ in the treatment of the VEGF/VEGFR-2-associated diseases by blocking the VEGF/VEGFR-2 signaling pathway, inhibiting VEGF and VEGFR-2 gene expression, blocking the binding of VEGF and VEGFR-2, and preventing the proliferation, migration, and survival of vascular endothelial cells expressing VEGFR-2.

This study analysed the expression of vascular endothelial growth factor-A (VEGF), VEGFR-2, and VEGFR-3 in primary cutaneous melanomas with positive and negative sentinel node status (SLN) (a total of 58 specimens divided into 2 groups of 29 for each status). The specimens were collected from the pathological archive of the department of Dermatology, Venereology and Allergology of the University Medical Center Heidelberg. A quantification score was developed for protein expression, by considering the percentage of positive melanoma cells (0: 0%, 1: up to 1%, 2: 2–10%, 3: 11–50%, and 4: > 50%) in relation to the intensity of staining (0: negative, 1: low, 2: medium, 3: strong). Tumoural VEGFR-3 expression (mean ± standard deviation) in SLN+ tumours (9.62 ± 3.09) was significantly stronger than in SLN– tumours (6.13 ± 3.87; p

Background and Objective: Angiogenesis and expression of angiogenic factors in tumor are associated with increased risk of metastasis and reduction of treatment outcomes. This study was performed to evaluate the effect of endurance training on the angiogenic factors (VEGFR-2, VEGF) of tumor in breast cancer bearing mice. Methods: In this experimental study, 20 BALB/c mice following breast cancer induction were randomly allocated into two groups of experimental (n=10) and control (n=10). Breast cancer tumors were induced by MC4-L2 cell infusion. Animals in the experimental group were received endurance training for 6 weeks, 5 days a week with gradual increase in intensity from 12 to 20 (m.min-1) and duration from 25 to 55 minutes. Tumor volume was measured weekly with digital caliper. Expression of two angiogenic proteins of VEGFR-2 and VEGF were measured by ELISA method. Results: Endurance training significantly reduced VEGFR-2 protein in training group (1.524±0.324 ng ml-1) compared to the control group (2.686±0.815 ng ml-1) (p

Background: The objective of this study was to detect the expression and distribution characteristics of five proteins (the hypoxia-inducible factor 1alpha [HIF-1a], HIF-2a, vascular endothelial growth factor [VEGF], VEGF-2 receptor [VEGFR-2] and hypoxia-induced mitogenic factor [HIMF]) in kidney of Tibetan sheep, plain sheep and goat. The results will provide the basic information for the comparative study of sheep breeds living at different altitudes.Materials and Methods: The kidney tissues were collected from healthy adult Tibetan sheep, plain sheep and goats and made into paraffin sections. Histological characteristics were assessed by haematoxylin and eosin staining. Expressions of HIF-1a, HIF-2a, VEGF, VEGFR-2 and HIMF proteins were measured by immunohistochemical staining.Results: Immunohistochemistry results showed that the positive expression signals of HIF-1a, HIF-2a, VEGF and VEGFR-2 were detected in epithelial cells of renal tubules and collecting tubules, renal corpuscles in the kidneys of the three sheep breeds. Positive expression signals of HIMF were detected in epithelial cells of proximal tubules and distal tubules in Tibetan sheep and epithelial cells of distal tubules in goat. Immunostaining intensity of HIF-1a, HIF-2a, VEGF and VEGFR-2 proteins in Tibetan sheep was significantly higher than that in both plain sheep and goat (p < 0.05). Immunostaining intensity of HIMF in Tibetan sheep was higher than goat (p < 0.05). Positive expression signals of HIMF were not detected in plain sheep.Conclusions: The expression and distribution characteristics of HIF-1a, HIF-2a, VEGF, VEGFR-2 and HIMF in the studied kidney tissues suggested that these proteins may be related to the physiological regulation of Tibetan sheep kidney in hypoxia environment, and therefore might be important regulating proteins for Tibetan sheep to adapt to high altitude hypoxia environment. [ABSTRACT FROM AUTHOR]

This study analysed the expression of vascular endothelial growth factor-A (VEGF), VEGFR-2, and VEGFR-3 in primary cutaneous melanomas with positive and negative sentinel node status (SLN) (a total of 58 specimens divided into 2 groups of 29 for each status). The specimens were collected from the pathological archive of the department of Dermatology, Venereology and Allergology of the University Medical Center Heidelberg. A quantification score was developed for protein expression, by considering the percentage of positive melanoma cells (0: 0%, 1: up to 1%, 2: 2-10%, 3: 11-50%, and 4: > 50%) in relation to the intensity of staining (0: negative, 1: low, 2: medium, 3: strong). Tumoural VEGFR-3 expression (mean ± standard deviation) in SLN+ tumours (9.62 ± 3.09) was significantly stronger than in SLN-tumours (6.13 ± 3.87; p < 0.001). A binary logistic regression model proved VEGFR-3 expression and tumour thickness to be significant independent predictors of SLN. These data provide evidence that VEGFR-3 expression may play a critical role in the pathogenesis of malignant melanoma and that its investigation may help to improve the selection of patients with primary cutaneous melanoma for sentinel node biopsy. [ABSTRACT FROM AUTHOR]

Early responses to a neurological excitotoxic process include blood‐brain barrier (BBB) impairment and overexpression of vascular endothelial growth factor (VEGF), but the long‐term effects of excitotoxicity on the BBB properties remain unknown. To assess this, we induced an excitotoxic process on male rats by neonatal monosodium glutamate (MSG) treatment. At postnatal day (PD) 60, we measured the expression level of structural proteins of the BBB and the VEGF type‐2 receptor (VEGFR‐2) protein in the cerebral motor cortex (CMC), striatum (STR), hippocampus (Hp), entorhinal cortex (Ent), and hypothalamus (Hyp). We also measured BBB permeability in the same cerebral regions. Neonatal MSG treatment significantly reduced the protein expression level of claudin‐5 in the CMC, and of ZO‐1 in the CMC and Hp, and increased the expression level of plasmalemmal vesicle‐associated protein in the CMC, and of VEGFR‐2 in all regions except for the Hyp. BBB permeability was significantly higher in all studied regions of MSG‐treated animals after hypertonic shock (HS). The increased BBB permeability observed in the MSG‐treated animals after HS was reversed by VEGFR‐2 inhibition with SU5416. We conclude that neonatal excitotoxicity leads to lasting impairment on BBB properties in adulthood, increasing its susceptibility to HS that could be regulated by VEGFR‐2 activity inhibition. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factors (VEGFs) regulate blood and lymph vessel development upon activation of three receptor tyrosine kinases (VEGFRs). The extracellular domain of VEGFRs consists of seven Ig-homology domains, of which D2-3 form the ligand-binding site, while the membrane proximal domains D4-7 are involved in homotypic interactions in ligand-bound receptor dimers. Based on low-resolution structures, we identified allosteric sites in D4-5 and D7 of vascular endothelial growth factor receptor 2 (VEGFR-2) accomplishing regulatory functions. Allosteric inhibition of VEGFR-2 signaling represents an attractive option for the treatment of neovascular diseases. We showed earlier that DARPin® binders to domains D4 or D7 are potent VEGFR-2 inhibitors. Here we investigated in detail the allosteric inhibition mechanism of the domain D4 binding inhibitor D4b. The 2.38 Å crystal structure of D4b in complex with VEGFR-2 D4-5, the first high-resolution structure of this VEGFR-2 segment, indicates steric hindrance by D4b as the mechanism of inhibition of receptor activation. At the cellular level, D4b triggered quantitative internalization of VEGFR-2 in the absence of ligand and thus clearance of VEGFR-2 from the surface of endothelial cells. The allosteric VEGFR-2 inhibition was sufficiently strong to efficiently inhibit the growth of human endothelial cells at suboptimal dose in a mouse xenograft model in vivo, underlining the therapeutic potential of the approach. [ABSTRACT FROM AUTHOR]

With the investigation of molecular targets, many agents, such as trastuzumab and ramucirumab, have attained a positive outcome in oncotherapy. Vascular endothelial growth factor (VEGF) is considered a potent factor in angiogenesis and plays an important role in the growth of tumors. Moreover, both VEGF and its receptor are usually excessively expressed in solid tumors and could be hopeful targets for the treatment of neoplasms. Apatinib (YN968D1) is an oral small-molecule tyrosine kinase inhibitor of VEGFR-2. By inhibiting several signaling transduction pathways, it restrains angiogenesis and subsequently controls tumorigenesis. According to current studies, apatinib shows promising application in various solid tumors as a post-second- and post-third-line treatment. It could significantly improve the median overall survival and progression-free survival of patients with tolerated adverse reactions. This paper aims to summarize the recent research on apatinib including the mechanism, pharmacokinetics, trials, adverse reactions, and prospect as a treatment. [ABSTRACT FROM AUTHOR]

The expression of СOX-2, VEGF, VEGFR-1, VEGFR-2, VEGFR-3, EGFR, endoglin (СD105), and IL-6 was analyzed in the human breast tumor cells having a varying metastatic potential. The role of these factors in the regulation of the metastatic potential of breast cancer cells, as well as that of COX-2 in the regulation of metastatic processes at the cellular level were examined. The potential capacity of human breast tumor cells to elaborate factors that stimulate tumor growth, angiogenesis, and metastasis was evaluated.

Aims: This study investigated the effect of low-intensity cathodal direct current (CDC) of electrical stimulation (ES) on the release of hypoxic inducible factor-1α (HIF-1α), nitric oxide (NO), vascular endothelial growth factor (VEGF), and soluble VEGF receptor-2 (sVEGFR-2) in the wound fluid of ischemic diabetic foot ulcers (DFUs).Methods: This study was a randomized, single-blind, placebo-controlled trial. Thirty type 2 diabetes patients with ischemic foot ulcerations were randomly assigned to receive either low-intensity CDC at sensory threshold (ES group, n=15) or placebo treatment (control group, n=15) for 1h/day, 3days/week, for 4weeks (12 sessions). After debridement during the first and twelfth treatment sessions, wound fluid was collected before and after ES application to determine the levels of HIF-1α, NO, VEGF, and sVEGFR-2. Wound surface area (WSA) was measured at the first, sixth, and twelfth sessions.Results: At the first session, after ES application, wound-fluid levels of HIF-1α were significantly increased (+61.98pg/mL) compared to the control group (-3.85pg/mL, P=0.01). After ES application at the first and twelfth sessions, wound-fluid levels of VEGF were also significantly increased (+36.77 and +39.57pg/mL, respectively) compared to the control group (+4.15 and +0.15pg/mL, P=0.007 and P=0.019, respectively). There was no significant effect on NO and sVEGFR-2 levels between the groups.Conclusions: Low-intensity CDC has positive effects on the release of HIF-1α and VEGF in the wound area of ischemic DFUs. Furthermore, our results suggest that applying ES to ischemic DFUs can be a promising way to promote angiogenesis and to achieve better outcomes in diabetic wound healing. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factor-A (VEGF) signals vascular development and angiogenesis mainly by binding to VEGF receptor family member 2 (VEGFR-2). Adaptor proteins mediate many VEGFR-2’s functions in the development of blood vessels. Cancer cells secrete VEGF to activate VEGFR-2 pathway in their neighboring endothelial cells in the process of cancer-related angiogenesis. Interestingly, activation of VEGFR-2 signaling is found in breast cancer cells, but its role and regulation are not clear. We highlighted research advances of VEGFR-2, with a focus on VEGFR-2’s regulation by mutant p53 in breast cancer. In addition, we reviewed recent FDA-approved tyrosine kinase inhibitor drugs that can inhibit the function of VEGFR-2. Ongoing preclinical and clinical studies might prove that pharmaceutically targeting VEGFR-2 could be an effective therapeutic strategy in treating triple negative breast cancer.

Excessive concentrations of vascular endothelial growth factor (VEGF) trigger angiogenesis, which causes complications such as the destabilization of atherosclerotic plaques and increased growth of tumors. This work focuses on the determination of the inhibitory activity of melatonin and other indolic related compounds on VEGF-induced VEGF receptor-2 (VEGFR-2) activation and an approximation to the molecular mechanism underlying the inhibition. Quantification of phosphorylated VEGFR-2 was measured by ELISA. Migration wound-healing assay was used to determine cell migration of human umbilical vein endothelial cells (HUVECs). This is the first time that melatonin, 3-indolacetic acid, 5-hydroxytryptophol, and serotonin are proved to significantly inhibit VEGF-induced VEGFR-2 activation in human umbilical vein endothelial cells and subsequent angiogenesis. 3-Indolacetic acid showed the highest inhibitory effect (IC50 value of 0.9704 mM), followed by 5-hydroxytryptophol (35% of inhibition at 0.1 mM), melatonin (30% of inhibition at 1 mM), and serotonin (24% of inhibition at 1 mM). An approximation to the molecular mechanism of the inhibition has been proposed, suggesting that indolic compounds might interact with the cell surface components of the endothelial membrane in a way that prevents VEGF from activating the receptor. Additionally, wound-healing assay revealed that exposure of HUVECs to melatonin and 3-indolacetic acid in the presence of VEGF significantly inhibited cell migration by 87% and 99%, respectively, after 24 h. These data demonstrate that melatonin, 3-indolacetic acid, 5-hydroxytryptophol, and serotonin would be good molecules for future exploitation as anti-VEGF signaling agents. [ABSTRACT FROM AUTHOR]

Postmenopausal osteoporosis is characterized by a reduction in the number of sinusoidal and arterial capillaries in the bone marrow and reduced bone perfusion. Thus, osteogenesis and angiogenesis are coupled in the process of osteoporosis formation and fracture healing. Naringin is the main ingredient of the root Rhizoma Drynariae, a traditional Chinese medicine, and it has potential effects on promoting fracture healing. However, whether naringin stimulates angiogenesis in the process of bone healing is unclear. Here, we show that naringin promotes fracture healing through stimulating angiogenesis by regulating the VEGF/VEGFR-2 signaling pathway in osteoporotic rats. [ABSTRACT FROM AUTHOR]

Angiogenesis is a multistep process that plays a key role in cancer growth and metastases. It is mediated through multiple vascular endothelial growth factor receptors (VEGFRs) and their ligands. The expression of VEGFR-2 is upregulated in tumor endothelial cells, and it is considered to be the primary receptor driving malignant angiogenesis. Ramucirumab (IMC-1121B, LY3009806) is a fully human monoclonal antibody that directly binds to VEGFR-2 with high affinity and specificity. It is also the most recent addition to our armamentarium of anti-angiogenic drugs approved for the treatment of metastatic colorectal cancer (CRC). The aim of this review is to summarize the pre-clinical and clinical development of ramucirumab and discuss its place in the current treatment paradigm for metastatic CRC. [ABSTRACT FROM AUTHOR]

Vascular endothelial growth factor receptor-2 (VEGFR-2) is the main receptor activated by vascular endothelial growth factor -A (VEGF-A) to promote tumour angiogenesis. Its clinical prognostic value has not been studied in canine mammary tumours (CMTs). Dogs with mammary cancer were enrolled in a survival study and the immunohistochemical expressions of VEGFR-2 and VEGF-A were analysed and associated with clinicopathological features. VEGFR-2 expression was associated with VEGF immunoreactivity in cancer cells, supporting the presence of an autocrine loop that may be involved in CMTs growth and survival. VEGFR-2 was also expressed by endothelial cells from tumour vasculature and positively associated with stromal matrix metalloproteinase-9 (MMP-9), suggesting the existence of a link between endothelial cells activation and up-regulation of matrix degrading proteins. Carcinosarcomas exhibited high VEGFR-2 expression suggesting that it may be one of the activated molecular pathways in this aggressive histological type and that VEGFR-2 inhibitors may constitute a potential treatment to improve the prognosis of these patients. Both VEGF and VEGFR-2 immunoreactivities were independent of patients' overall survival (OS) and disease-free survival (DFS). [ABSTRACT FROM AUTHOR]

Background: We previously reported that dietary glucosylceramides show cancer-prevention activity in a mouse xenograft model of human head and neck cancer cells (SCCKN). However, the mechanism was unclear. Ceramides, metabolites of glucosylceramides, induce apoptotic cell death in various malignancies. Here, we investigated the inhibitory effects of dietary glucosylceramides on tumor growth in vivo and in vitro. Methods: SCCKN were subcutaneously inoculated into the right flanks of NOD/SCID mice. Mice were treated with or without dietary glucosylceramides (300 mg/kg) daily for 14 consecutive days after confirmation of tumor progression. Microvessel areas around the tumor were assessed by hematoxylin-eosin staining and immunohistochemistry of CD31, and, as markers for angiogenesis, protein levels of VEGF, VEGF receptor-2, and HIF-1α were assessed by Western blotting. Mass spectrometry was performed to measure the levels of sphingolipids in mouse serum after treatment with dietary glucosylceramides. Results: Oral administration of glucosylceramides significantly decreased SCCKN growth in the xenograft model with inhibition of angioinvasion. In tumor-invasive areas, VEGF and HIF-1α in the tumor cells, and VEGF receptor-2 in endothelial cells decreased after treatment with dietary glucosylceramides. Dietary glucosylceramides increased serum levels of sphingosine-based ceramides as compared to the control. In SCCKN and UV♀2 cells, C6-ceramide suppressed the expressions of VEGF, VEGF receptor-2, and HIF-1α in vitro. Conclusion: These results suggest that dietary glucosylceramides trigger the de novo pathway of ceramide synthesis, indicating that sphingosine-based ceramide suppresses the growth of head and neck tumors through the inhibition of pro-angiogenic signals such as VEGF, VEGF receptor-2, and HIF-1α. [ABSTRACT FROM AUTHOR]

Purpose: Hypothyroidism is a common adverse event in patients treated with anti-VEGFR-2 targeting agents and may be a valuable predictive factor of efficacy. Famitinib is an inhibitor of multiple tyrosine kinases mainly targeting VEGFR-2. The objectives of this study were to assess the efficacy and safety of famitinib in patients with pretreated HER2-negative metastatic breast cancer (MBC) and to explore potential of famitinib-induced hypothyroidism and serum vascular endothelial growth factor (VEGF) level for efficacy prediction. Materials and methods: The primary end point was objective response rate (ORR). Famitinib was administered 25 mg/d. Thyroid function assessments were done at baseline and then every 4 weeks. Plasma levels of VEGF were determined at baseline and 2 cycles after treatment. Results: A total of 28 patients were enrolled. ORR was 14.3 %. The most common grade 3/4 AEs were hand-foot syndrome (25.0 %), proteinuria (21.4 %) and hypertension (17.9 %). 64.0 % patients were observed with elevated thyroid-stimulating hormone (TSH) (>4.94 mIU/L) at any time during the entire treatment period. Sixteen patients with an elevated TSH had a significantly longer PFS than nine patients with no TSH elevation (107 vs. 53 days, respectively, P = 0.002). TSH elevation was also an independent predictor of PFS in a Cox regression model. Plasma VEGF levels did not correlate significantly with clinical outcomes. Conclusions: Famitinib did show substantial anti-tumor activities with a good safety profile in heavily pretreated patients with HER2-negative MBC. Famitinib-related TSH increase may be an early indicator of its efficacy. Serial monitoring of serum TSH may help define VEGFR-2-dependent or VEGFR-2-independent drug resistance. [ABSTRACT FROM AUTHOR]

Abstract: Vascular endothelial growth factor VEGF (VEGF-A or VEGF165) is a potent angiogenic factor that also signals neuroprotection through activation of its cognate receptor VEGFR-2. In this capacity, VEGF signaling can rescue neurons from the damage induced by stressful stimuli many of which elicit oxidative stress. However, the regulatory role that VEGFR-2 plays in providing neuroprotection remains elusive. Therefore, we investigated the effects of VEGFR-2 inhibition on primary cultures of mature hippocampal neurons undergoing nutritional stress. We found that neurons cultured under nutritional stress had increased expression of VEGF and its receptors, VEGFR-1, VEGFR-2, and NP-1, as well as enhanced levels of VEGFR-2 phosphorylation. These neurons also showed increased activation of the prosurvival pathways for MEK/ERK1/2 and PI3K/Akt, enhanced phosphorylation (inactivation) of the proapoptotic BAD, and higher levels of the antiapoptotic protein Bcl-xL, all of which were augmented by treatments with exogenous VEGF and blocked by VEGFR-2 inhibition. The blockade of VEGFR-2 function also elicited a cytotoxicity that was accompanied by caspase-3 activation, induction of hemeoxygenase-1 (HO-1), oxidative stress, and a collapse in the mitochondrial membrane potential (ΔΨm). Knockdown of VEGFR-2 by siRNA generated a similar pattern of redox change and mitochondrial impairment. Pretreatments with VEGF, VEGF-B, or the antioxidant N-acetylcysteine (NAC) rescued SU1498 or siRNA-treated neurons from the mitochondrial dysfunction and oxidative stress induced by VEGFR-2 inhibition in a timely fashion. These findings suggested that VEGF or VEGF-B can provide neuroprotection by signaling through an alternate VEGF receptor. Together, our findings suggest that VEGF signaling through VEGFR-2 plays a critical regulatory role in protecting stressed hippocampal neurons from the damaging effects of an oxidative insult. These findings also implicate VEGFR-1 or NP-1 as compensatory receptors that mediate neuroprotection when VEGFR-2 function is blocked. [Copyright &y& Elsevier]

Low-level laser therapy (LLLT) has been widely used in the treatment of the stomatognathic system dysfunction; however, its biological effect remains poorly understood. This study evaluated the effect of LLLT (GaAlAs, 780 nm, 20 J/cm², 40 mW) on masseter muscle of HRS/J mice after different numbers of laser irradiations (three, six, and ten) for 20 s in alternate days. Three experimental groups were defined according to the number of laser irradiations and three control groups ( n = 5) were used. On the third day after the last irradiation, all animals were killed and the masseter muscle was removed and processed for the following analysis: (a) transmission electron microscopy, (b) zymography, (c) immunohistochemistry for vascular endothelial growth factor (VEGF) and VEGFR-2. The results showed: (a) with six laser applications, a dilation of T tubules, and sarcoplasmic reticulum cistern, increased pinocytosed vesicles in the endothelium; with ten laser applications, few pinocytic vesicles in the endothelium and condensed mitochondria. (b) Under the conditions of this study, the synthesis of other matrix metalloproteinases was not observed, only the MMP-2 and -9. (c) After ten laser irradiations, immunostaining was observed only for VEGFR-2. We conclude that after six laser applications, ultrastructural changes may facilitate the Ca transfer to cytosol and increase the fluid transport from one surface to another. The ultrastructural changes and no immunostaining for VEGF with ten applications may decrease the metabolic activity as well as damage the angiogenic process, suggesting that an effective number of laser applications may be less than ten, associating to this therapy a better cost-benefit. [ABSTRACT FROM AUTHOR]

This review is designed to provide an overview of the current literature concerning vascular endothelial growth factor signaling (VEGF) in acute myeloid leukemia (AML). Aberrant VEGF signaling operates in the bone marrow of AML patients and is related to a poor prognosis. The altered signaling pathway demonstrated to interfere in several autocrine and paracrine signaling pathways. VEGF signaling promotes autocrine AML blast cell proliferation, survival, and chemotherapy resistance. In addition, VEGF signaling can mediate paracrine vascular endothelial cell-controlled angiogenesis in AML. Both effects presumably explain the association of high VEGF levels and poor therapeutic outcome. More recently, researches focusing on bone marrow stem cell niches demonstrate a role for VEGF signaling in the preservation of several cell types within these niches. The bone marrow niches are proposed to be a protective microenvironment for AML cells that could be responsible for relapses in AML patients. This implies the need of sophisticated VEGF-targeted therapeutics in AML therapy strategies. This review highlights our current understanding of aberrant VEGF signaling in AML, appoints the interference of VEGF signaling in the AML-associated microenvironment, and reflects the novelty of current VEGF-targeted therapeutics used in clinical trails for the treatment of AML. [ABSTRACT FROM AUTHOR]

In neonatal jaundice, high levels of unconjugated bilirubin (UCB) may induce neurological dysfunction (BIND). Recently, it was observed that UCB induces alterations on brain microvasculature, which may facilitate its entrance into the brain, but little is known about the steps involved. To evaluate if UCB damages the integrity of human brain microvascular endothelial cells (HBMECs), we used 50 or 100 μM UCB plus human serum albumin, to mimic the neuropathological conditions where levels of UCB free species correspond to moderate and severe neonatal jaundice, respectively. Our results point to a biphasic response of HBMEC to UCB depending on time of exposure. The early response includes increased number of caveolae and caveolin-1 expression, as well as upregulation of vascular endothelial growth factor (VEGF) and its receptor 2 (VEGFR-2) with no alterations of the paracellular permeability. In contrast, effects by sustained hyperbilirubinemia are the reduction in zonula occludens (ZO)-1 and β-catenin levels and thus of tight junctions (TJ) strands and cell-to-cell contacts. In addition, reduction of the transendothelial electrical resistance (TEER) and increased paracellular permeability are observed, revealing loss of the barrier properties. The 72 h of HBMEC exposure to UCB triggers a cell response to the stressful stimulus evidenced by increased autophagy. In this later condition, the UCB intracellular content and the detachment of both viable and non-viable cells are increased. These findings contribute to understand why the duration of hyperbilirubinemia is considered one of the risk factors of BIND. Indeed, facilitated brain entrance of the free UCB species will favor its parenchymal accumulation and neurological dysfunction. [ABSTRACT FROM AUTHOR]

Abstract: The present study evaluates by ultrastructural and immunohistochemical methods, the possible changes on muscular tissue affected by LLLI during a treatment, for example, in cases of temporomandibular joint disorders. Sixty male Wistar rats divided into 6 groups (n =10) received ten laser irradiations, with different energy densities (groups I-0; II-0.5; III-1.0; IV-2.5; V-5.0; and VI-20J/cm2). Muscles were removed and processed for transmission electron microscopic and immunohistochemical (VEGF and VEGFR-2) analyses. Captured photomicrographs of immunohistochemistry and transmission electron microscopy were evaluated. It was observed in the irradiated muscles, mitochondria of different shapes and sizes, with increased plasticity evidenced by organelles in fusion, division and the presence of elongated structures with characteristics of mitochondria, proximity with the dilated sarcoplasmatic reticulum, suggesting organelles with large amounts of energy, and the presence of cytoplasmic protrusions in the capillaries with high dosages. All studied groups showed immunostainings for both markers (VEGF and VEGFR-2), but in general those who received higher doses also showed the markings more pronounced, suggesting dose-dependent biomodulation. It was concluded that the LLLI was able to modify the ultrastructural characteristics and immunohistochemical pattern of VEGF and VEGFR-2 in the masseter muscle of rats. [Copyright &y& Elsevier]

Peroxisome proliferator-activated receptor γ (PPARγ) activation has anti-angiogenic and apoptotic effects in endothelial cells. Here, we investigated the mechanisms of the anti-angiogenic action of a novel PPARγ ligand, KR-62980. KR-62980 inhibited in vitro basal tube formation and in vivo neovascularization in mice induced by Matrigel containing vascular endothelial growth factor (VEGF, 5 ng/ml). VEGF-induced cell proliferation and chemotactic migration in human umbilical vein endothelial cells (HUVECs) were also suppressed by KR-62980, in a mechanism accompanied by apoptotic cell death. KR-62980 downregulated the VEGF-induced VEGFR-2 expression but increased the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression in parallel with reduced phosphorylation of extracellular signal-related kinase 1/2 (ERK1/2), PI3K p85α, and p38 MAPK. The knockdown of PTEN expression abolished KR-62980-suppressed cell proliferation and angiogenesis. All of the effects of KR-62980 disappeared with pretreatment of bisphenol A diaglycidyl ether (BADGE), a PPARγ antagonist. In summary, KR-62980 inhibited VEGF-induced angiogenesis in HUVECs by PPARγ-mediated dual mechanisms: VEGFR-2 downregulation and PTEN upregulation. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The vascular endothelial growth factor (VEGF) family of ligands and receptors (VEGFR) play an important role in tumor angiogenesis. Increased expression of angiogenic factors in tumors or in blood is associated with poor prognosis. The aim of this study was to investigate the role of VEGF-A and soluble VEGFR-2 (sVEGFR-2) as biomarkers in advanced non-small-cell lung cancer (NSCLC). Methods: We studied 432 patients with advanced NSCLC (stages IIIB–IV) treated with cisplatin and docetaxel and 89 healthy age-matched controls. Blood samples were collected before chemotherapy, and VEGF-A and sVEGFR-2 levels were determined by ELISA. Results: VEGF-A and sVEGFR-2 levels were higher in NSCLC patients than in the controls, but VEGF-A behaves as a better diagnostic biomarker. There were no significant associations between VEGF-A and sVEGFR-2 concentrations and clinical characteristics, such as ECOG-PS, gender, stage, histology, metastases, and treatment response. A patient subgroup characterized by a combination of high VEGF-A and low sVEGFR-2 levels exhibited the worst patient prognoses in terms of TTP and OS. Conclusions: VEGF-A and sVEGFR-2 levels were significantly higher in patients than in the controls. A combination of VEGF-A and sVEGFR-2 can be used as an independent prognostic biomarker in advanced NSCLC. [Copyright &y& Elsevier]

Background: It is well known that the vascular endothelial growth factor (VEGF) system is essential to the growth of tumors, but its possible changes during tumor development are still sparsely elucidated. The current study, therefore, investigated the possible differences of VEGF and VEGFR-1 and VEGFR-2 protein concentration in tissue from patient groups with normal ovaries and those with benign, borderline, and malignant ovarian tumors. Furthermore, we investigated VEGF gene expression of the same groups. Material and Methods: We analyzed tissue samples from 157 patients undergoing surgery of the ovaries. Tissue VEGF and VEGFR-1 and VEGFR-2 were measured by enzyme-linked immunosorbent assay, and gene expression was analyzed by reverse transcriptase polymerase chain reaction regarding VEGF isotypes 121, 165, and 189. Results: Significantly higher VEGF protein concentration was found in malignant tissue compared with normal ovarian tissue (P < 10-6) and benign ovarian tumors (P < 10-6). Similar results were found with respect to VEGFR-1. The gene expression differed among normal ovaries, benign, and malignant tumors for all Three VEGF isotypes (P < 10-6), with significantly higher levels of VEGF mRNA in malignant tumors. Malignant tumors with VEGFR-2 protein levels above the median had decreased progression-free survival (PFS) (P = .0005) and overall survival (P = .002). Median PFS was 26.2 months in the group with low VEGFR-2 levels vs. 7.8 months in the other group. Multivariate analysis confirmed the results (hazard ratio, 1.94; P = .04). Conclusion: The current study showed major changes in the VEGF system during tumor development. A significant difference was found in protein concentration and gene expression among the different patient groups. In addition, VEGFR-2 was correlated with PFS and overall survival. [ABSTRACT FROM AUTHOR]

Background. Vascular endothelial growth factor (VEGF) expression seems to be associated with worse overall survival in patients with head and neck squamous cell carcinoma. The purposes of this study were to assess the prognostic values of the immunohistochemical expression of VEGF and vascular endothelial growth factor receptor-2 (VEGFR-2) in a cohort of patients with operable advanced laryngeal cancer who had been treated with induction chemotherapy.Methods. VEGF and VEGFR-2 expression in the malignant cells was quantified by an enzyme immunosorbent assay in a retrospective series. Results. Fifty-nine patients were included in this study. Wefound moderate to high VEGF expression in 61% of patients and none to low expression in 39%. VEGFR-2 expression was moderate to high in 58% of patients and was none to low in 42%. The probability of a complete response to induction chemotherapy was significantly higher in patients with none to low VEGF expression (74% vs 40%; p ¼ .02). Conclusion. VEGF expression seems to be a significant predictor of complete response to induction chemotherapy. [ABSTRACT FROM AUTHOR]

Abstract: Angiogenic factors, such as vascular endothelial growth factor (VEGF), its receptors and epidermal growth factor receptor (EGF-R), are involved in increased progression in many carcinomas. The aim of this study was to investigate the role of angiogenesis and immunolocalization of VEGF, its receptors, EGF-R and Ki 67 in leiomyomas and leiomyosarcomas using an indirect immunohistochemical method. Samples from patients with leiomyoma, cellular leiomyoma and cellular leiomyosarcoma (n=20 per group) were fixed in 10% formalin and processed using routine paraffin protocols. Following initial histological analysis, samples were immunostained with primary antibodies for VEGF, VEGFR-1, VEGFR-2, EGF-R and Ki-67 using an indirect avidin–biotin peroxidase method. Immunostaining intensities were evaluated as mild, moderate or strong and a semi-quantitative method (H-Score) was used to compare the samples. While mild/moderate EGF-R immunostaining and moderate immunostaining for VEGF and its receptors were observed in samples of leiomyomas, much less immunoreactivity was observed in cellular leiomyomas. All immunoreactivities and immune-stained cells increased in leiomyosarcomas. When scores of intensity and percentage of positive staining cells were compared, all immunoreactivities were shown to be significantly increased in leiomyosarcomas compared to leiomyomas. These results suggest that in leiomyosarcoma, angiogenic factors, such as VEGF, its receptors and EGF-R, may be involved in tumor angiogenesis. Active tumor cells can trigger angiogenesis, interaction with surrounding tissue and in the tissue itself initiating angiogenic activity. Angiogenic growth factors play an important role and induce malignant transformation through both autocrine and paracrine mechanisms. Anti-angiogenic agents may provide a novel therapeutic approach for the treatment of leiomyosarcoma. [Copyright &y& Elsevier]

Vascular Endothelial Growth Factor Receptor (VEGFR) mediated signalling drives angiogenesis. This is predominantly attributed to the activity of VEGFR-2 following binding of VEGF-A. Whether other members of the VEGFR and ligand families such as VEGFR-1 and its ligand Placental Growth Factor (PlGF) can also contribute to developmental and pathological angiogenesis is less clear. We explored the function of PlGF in VEGF-A dependent angiogenesis using an in vitro co-culture assay in which endothelial cells are cultured on a fibroblast feeder layer. In the presence of 2% FS MCDB media (containing limited growth factors) in vitro endothelial tube formation is driven by endogenous angiogenic stimuli which are produced by the fibroblast and endothelial cells. Under these conditions independent sequestration of either free VEGF-A or PlGF with polyclonal and monoclonal antibodies inhibited tube formation suggesting that both ligands are required to drive an angiogenic response. Endothelial tube formation could only be driven within this assay by the addition of exogenous VEGF-A, VEGF-E or VEGF-A/PlGF heterodimer, but not by PlGF alone, implying that activation of either VEGFR-2/VEGFR-1 heterodimers or VEGFR-2 homodimers were responsible for eliciting an angiogenic response directly, but not VEGFR-1 homodimers. In contrast to results obtained with an endogenous angiogenic drive, sequestration of PlGF did not affect endothelial tube formation when the assay was driven by 1 ng/ml exogenous VEGF-A. These data suggest that although neutralising PlGF can be shown to reduce endothelial tube formation in vitro, this effect is only observed under restricted culture conditions and is influenced by VEGF-A. Such data questions whether neutralising PlGF would have a therapeutic benefit in vivo in the presence of pathological concentrations of VEGF-A. [ABSTRACT FROM AUTHOR]

Abstract: Investigations over the last decade have established the essential role of growth factors and their receptors during angiogenesis and carcinogenesis. The vascular endothelial growth factor receptor (VEGFR) family in mammals contains three members, VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1) and VEGFR-3 (Flt-4), which are transmembrane tyrosine kinase receptors that regulate the formation of blood and lymphatic vessels. In the early 1990s, the above VEGFR was structurally characterized by cDNA cloning. Among these three receptors, VEGFR-2 is generally recognized to have a principal role in mediating VEGF-induced responses. VEGFR-2 is considered as the earliest marker for endothelial cell development. Importantly, VEGFR-2 directly regulates tumor angiogenesis. Therefore, several inhibitors of VEGFR-2 have been developed and many of them are now in clinical trials. In addition to targeting endothelial cells, the VEGF/VEGFR-2 system works as an essential autocrine/paracrine process for cancer cell proliferation and survival. Recent studies mark the continuous and increased interest in this related, but distinct, function of VEGF/VEGFR-2 in cancer cells: the autocrine/paracrine loop. Several mechanisms regulate VEGFR-2 levels and modulate its role in tumor angiogenesis and physiologic functions, i.e.: cellular localization/trafficking, regulation of cis-elements of promoter, epigenetic regulation and signaling from Notch, cytokines/growth factors and estrogen, etc. In this review, we will focus on updated information regarding VEGFR-2 research with respect to the molecular mechanisms of VEGFR-2 regulation in human breast cancer. Investigations in the activation, function, and regulation of VEGFR-2 in breast cancer will allow the development of new pharmacological strategies aimed at directly targeting cancer cell proliferation and survival. [Copyright &y& Elsevier]