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Tumor angiogenesis is characterized by deregulated gene expression in endothelial cells (EC). While studies until now have mainly focused on overexpressed genes in tumor endothelium, we here describe the identification of transcripts that are repressed in tumor endothelium and thus have potential suppressive effects on angiogenesis. We identified nineteen putative angiosuppressor genes, one of them being bromodomain containing 7 (BRD7), a gene that has been assigned tumor suppressor properties. BRD7 was studied in more detail, and we demonstrate that BRD7 expression is inversely related to EC activation. Ectopic expression of BRD7 resulted in a dramatic reduction of EC proliferation and viability. Furthermore, overexpression of BRD7 resulted in a bromodomain-dependent induction of NFκB-activity and NFκB-dependent gene expression, including ICAM1, enabling leukocyte-endothelial interactions. In silico functional annotation analysis of genome-wide expression data on BRD7 knockdown and overexpression revealed that the transcriptional signature of low BRD7 expressing cells is associated with increased angiogenesis (a.o. upregulation of angiopoietin-2, VEGF receptor-1 and neuropilin-1), cytokine activity (a.o. upregulation of CXCL1 and CXCL6), and a reduction of immune surveillance (TNF-α, NFκB, ICAM1). Thus, combining in silico and in vitro data reveals multiple pathways of angiosuppressor and anti-tumor activities of BRD7. [ABSTRACT FROM AUTHOR]

A potential for the use of propolis in preventive and therapeutic purposes has been acknowledged, but little attention has been paid to estimation of possible propolis cytotoxicity with respect to astrocytes. We tried to estimate how a propolis ethanol extract (PEE) affects rat brain astrocytes in vitro and also to uncover crucial molecular targets of the PEE action. Primary astrocytes were exposed to PEE in doses of 10, 25, or 100 μg/ml for 24 h, and then the cell viability was monitored by MTT assay. Levels of glial fibrillary acidic protein (GFAP), transcriptional nuclear factor-κB (NF-κB), poly(ADPribose) polymerase (PARP), and angiostatins were measured using Western blot to identify the molecular mechanisms underlying cell responses to PEE. The PEE treatment exerted a dose-dependent cytotoxic effect on cultured astrocytes. The PEE modulated astrocyte signaling pathways through inducing the expression of NF-κB and PARP. At the same time, the PEE stimulated GFAP synthesis and fibrillogenesis, which was indicative for activation of astrocytes preceding their suppression. The PEE significantly increased the production of angiostatin isoforms by astrocytes, thus contributing to an antiangiogenic potential of these cells. In summary, our results indicated that exposure to the PEE exerts certain cytotoxic effects on astrocytes in a dose-dependent manner; these effects are realized through modulation of cytoskeleton rearrangements and pro-apoptotic signaling pathways. A widely available, safe, and inexpensive substance, propolis, and its components and derivatives may be used in the prevention and treatment of neuronal impairments, including malignant tumors and neurodegenerative disorders associated with excessive astrocytic activation. [ABSTRACT FROM AUTHOR]

Cancer cells are often dependent on epigenetic pathways for their survival. Consequently, drugs that target the epigenome, rather than the underlying DNA sequence, are currently attracting considerable attention. In recent years, the first epigenetic drugs have been approved for cancer chemotherapy, mainly for hematological applications. Limitations in single-drug efficacies have thus far limited their application in the treatment of solid tumors. Nevertheless, promising activity for these compounds has been suggested when combined with other, distinctly targeted agents. In this review, we discuss the anti-angiogenic activity of histone deacetylase and DNA methyltransferase inhibitors and their combinations with other targeted (anti-angiogenic) therapeutics in treatment of solid tumors. The role that these inhibitors play in the inhibition of tumor angiogenesis, particularly in combination with other targeted agents, and the advantages they present over broad acting anticancer agents, are critically discussed. [ABSTRACT FROM AUTHOR]

Diabetic retinopathy (DR) is a multifactorial disease characterized by reactive gliosis and disbalance of angiogenesis regulators, contributing to endothelial dysfunction and microvascular complications. This study was organized to elucidate whether poly(ADP-ribose) polymerase-1 (PARP-1) inhibition could attenuate diabetes-induced damage to macroglia and correct angiogenic disbalance in diabetic rat retina. After 8 weeks of streptozotocin (STZ)-induced diabetes, Wistar male rats were treated with PARP-1 inhibitors, nicotinamide (NAm) or 3-aminobenzamide (3-AB) (100 and 30 mg/kg/daily i.p., respectively), for 14 days. After the 10-weeks experiment period, retinas were undergone an immunohistochemical staining for glial fibrillary acidic protein (GFAP), while western blots were performed to evaluate effects of PAPR-1 inhibitors on the levels of PARP-1, poly(ADP-ribosyl)ated proteins (PARs), GFAP, and angiostatin isoforms. Diabetes induced significant up-regulation and activation of retinal PARP-1, reactive gliosis development, and GFAP overexpression compared to non-diabetic control. Moreover, extensive fragmentation of both PARP-1 and GFAP (hallmarks of apoptosis and macroglia reactivation, respectively) in diabetic retina was also observed. Levels of angiostatin isoforms were dramatically decreased in diabetic retina, sustaining aberrant pro-angiogenic condition. Both NAm and 3-AB markedly attenuated damage to macroglia, evidenced by down-regulation of PARP-1, PARs and total GFAP compared to diabetic non-treated group. PARP-1-inhibitory therapy prevented formation of PARP-1 and GFAP cleavage-derived products. In retinas of anti-PARP-treated diabetic animals, partial restoration of angiostatin's levels was shown. Therefore, PARP-1 inhibitors counteract diabetes-induced injuries and manifest retinoprotective effects, including attenuation of reactive gliosis and improvement of angiogenic status, thus, such agents could be considered as promising candidates for DR management. [ABSTRACT FROM AUTHOR]

Drug combinations can improve angiostatic cancer treatment efficacy and enable the reduction of side effects and drug resistance. Combining drugs is non-trivial due to the high number of possibilities. We applied a feedback system control (FSC) technique with a population-based stochastic search algorithm to navigate through the large parametric space of nine angiostatic drugs at four concentrations to identify optimal low-dose drug combinations. This implied an iterative approach of in vitro testing of endothelial cell viability and algorithm-based analysis. The optimal synergistic drug combination, containing erlotinib, BEZ-235 and RAPTA-C, was reached in a small number of iterations. Final drug combinations showed enhanced endothelial cell specificity and synergistically inhibited proliferation ( p < 0.001), but not migration of endothelial cells, and forced enhanced numbers of endothelial cells to undergo apoptosis ( p < 0.01). Successful translation of this drug combination was achieved in two preclinical in vivo tumor models. Tumor growth was inhibited synergistically and significantly ( p < 0.05 and p < 0.01, respectively) using reduced drug doses as compared to optimal single-drug concentrations. At the applied conditions, single-drug monotherapies had no or negligible activity in these models. We suggest that FSC can be used for rapid identification of effective, reduced dose, multi-drug combinations for the treatment of cancer and other diseases. [ABSTRACT FROM AUTHOR]

Multipotent mesenchymal stromal (stem) cells (MSCs) are a heterogeneous cell population of different commitment and are actively involved in the physiological and regenerative tissue remodeling. MSC mobilization from local tissue depots and their activation at sites of tissue damage are the key issues in the study of mechanisms of MSC functional activity implementation. Short-term hypoxic stress that is considered as a constitutive feature of the damage foci, may contribute to the activation MSC potential. This review is analysed the data on the impact of short (less than 72 h) hypoxic stress ex vivo on the viability and functional activity of MSCs. [ABSTRACT FROM AUTHOR]

The main physiological function of plasmin is blood clot fibrinolysis and restoration of normal blood flow. To date, however, it became apparent that in addition to thrombolysis, the plasminogen/plasmin system plays an important physiological and pathological role in a number of other essential processes: degradation of the extracellular matrix, embryogenesis, cell migration, tissue remodeling, wound healing, angiogenesis, inflammation, and tumor cell migration. This review focuses on structural features of plasminogen, regulation of its activation by physiological plasminogen activators, inhibitors of plasmin, and plasminogen activators, and the role of plasminogen binding to fibrin, cellular receptors, and extracellular ligands in various functions performed by plasmin thus formed. [ABSTRACT FROM AUTHOR]

Angiogenesis, a process of formation of new blood vessels form pre-existing vessels, is regulated by a large number of peptide factors. Imbalance of pro- and anti-angiogenic factors appears to be the major cause of vascular abnormalities leading to various complications in diabetes mellitus. Angiostatins, kringle-containing fragments of plasminogen/plasmin, are among of the most potent physiological inhibitors of neovascularization. In this review we focus on the colligation and analysis of the available data on peculiarities of production of angiostatins and their functioning in diabetes mellitus conditions. Special attention is paid to the role of angiostatins in the pathogenesis of typical diabetic complications, including retinopathies, nephropathies, and cardiovascular diseases. [ABSTRACT FROM AUTHOR]

α1(IV)NC1 inhibits angiogenesis by regulating MAPK activation, this biological function was partly attributed α1(IV)NC1 binding to α1β1-integrin. However, its potent antiangiogenic activity and the molecular targets of α1(IV)NC1 has not been investigated. In the present study, the regulation of MMP-2 activation by α1(IV)NC1 was evaluated. α1β1-integrin which is required for inhibition of angiogenesis is not playing a role in cellular invasion and inhibition of MMP-2 activation by α1(IV)NC1. We found that α1(IV)NC1 binds the CBD of MMP-2 and forming a stable complex that prevents activation of MMP-2. The antiangiogenic activity of α1(IV)NC1 is mediated, in part, by this binding activity. In addition, up-regulation of TIMP-2 by α1(IV)NC1 led to saturation of MT1-MMP binding sites, which in turn led to inhibition of MMP-2 activation. In-vivo studies using α1-integrin null-mice treated with higher doses of α1(IV)NC1 showed integrin independent inhibition of tumor growth and active-MMP-2, without affecting MMP-9, MMP-7 and angiostatin. [ABSTRACT FROM AUTHOR]

Chronic urticaria (CU) is a common disease characterized by recurrent itchy wheals and/or angioedema for more than 6 weeks. Increased levels of the pro-angiogenic mediator vascular endothelial growth factor (VEGF) have been described in skin disorders, such as chronic urticaria (CU), psoriasis and atopic dermatitis. Up to now, no data on the role of VEGF endogenous inhibitors Endostatin (ES) and Thrombospondin-1 (TSP-1) in CU are available. The aim of our study is to investigate the potential involvement of ES and TSP-1 in patients with chronic spontaneous urticaria (CSU). The levels of ES and TSP-1 were measured in the sera of 106 adult patients with CSU and 98 healthy subjects by enzyme immunoassays. The serum levels of the anti-angiogenic mediators ES and TSP-1 resulted significantly higher in CSU than in control subjects. Analysis of these mediators in CSU sub-groups, defined by the results of the autologous serum skin test (ASST), identified a significant increase of ES and TSP-1 in both ASST-positive and ASST-negative sub-groups as compared to the controls. Levels of ES and TSP-1 do not parallel the disease severity in CSU. Our study suggests that the extracellular matrix (ECM) fragments ES and TSP-1 with anti-angiogenic activity play a potential role in the pathogenesis of CSU but do not parallel disease activity. [ABSTRACT FROM AUTHOR]

There is a critical need to identify molecules that modulate the biology of neutrophils because activated neutrophils, though necessary for host defense, cause exuberant tissue damage through production of reactive oxygen species and increased lifespan. Angiostatin, an endogenous anti-angiogenic cleavage product of plasminogen, binds to integrin αβ, ATP synthase and angiomotin and its expression is increased in inflammatory conditions. We test the hypothesis that angiostatin inhibits neutrophil activation, induces apoptosis and blocks recruitment in vivo and in vitro. The data show immuno-reactivity for plasminogen/angiostatin in resting neutrophils. Angiostatin conjugated to FITC revealed that angiostatin was endocytozed by activated mouse and human neutrophils in a lipid raft-dependent fashion. Co-immunoprecipitation of human neutrophil lysates, confocal microscopy of isolated mouse and human neutrophils and functional blocking experiments showed that angiostatin complexes with flotillin-1 along with integrin αβ and ATP synthase. Angiostatin inhibited fMLP-induced neutrophil polarization, as well as caused inhibition of hsp-27 phosphorylation and stabilization of microtubules. Angiostatin treatment, before or after LPS-induced neutrophil activation, inhibited phosphorylation of p38 and p44/42 MAPKs, abolished reactive oxygen species production and released the neutrophils from suppressed apoptosis, as indicated by expression of activated caspase-3 and morphological evidence of apoptosis. Finally, intravital microscopy and myeloperoxidase assay showed inhibition of neutrophil recruitment in post-capillary venules of TNFα-treated cremaster muscle in mouse. These in vitro and in vivo data demonstrate angiostatin as a broad deactivator and silencer of neutrophils and an inhibitor of their migration. These data potentially open new avenues for the development of anti-inflammatory drugs. [ABSTRACT FROM AUTHOR]

Loss of glomerular function associated with the presence of tubulointerstitial lesions, which are characterized by peritubular capillary loss, is a common finding in progressive renal disorders. Dysregulated expression of angiogenic factors (such as vascular endothelial growth factor [VEGF] and angiopoietins) and endogenous angiogenic inhibitors (such as thrombospondin-1, angiostatin and endostatin) underlie these conditions and negatively influence the balance between capillary formation and regression, resulting in capillary rarefaction. Recent studies have provided unequivocal evidence for a pathogenic role of tubulointerstitial hypoxia and the involvement of hypoxia-inducible transcription factors in the advanced stages of chronic kidney disease. The mainstay of potential angiogenic therapies is the application of angiogenic factors with the primary aim of ameliorating reduced oxygenation in the ischaemic tubulointerstitium. However, this strategy is strongly associated with inflammation and changes in vascular permeability. For example, supraphysiological expression of VEGF results in glomerular expansion and proteinuria, whereas VEGF blockade using neutralizing antibodies can cause hypertension and thrombotic microangiopathy. These effects highlight the importance of tight regulation of angiogenic factors and inhibitors. Novel therapeutic approaches that target vascular maturation and normalization are now being developed to protect kidneys from capillary rarefaction and hypoxic injury. [ABSTRACT FROM AUTHOR]

The present work formulates and analyzes the inhibitory effect of anti-angiogenic factor angiostatin excreted by the primary tumor on metastatic tumor angiogenesis, blood perfusion, and interstitial fluid flow in the tumor microenvironment by means of a numerical experiment. The simulation results demonstrate that angiostatin has an obvious impact on the morphology, growth rate, and the number of branches of microvascular network inside and outside the metastatic tumor, and angiostatin has the capacity to regulate and inhibit the formation of new blood vessels. Heterogeneous blood perfusion, widespread interstitial hypertension, and low convection within the metastatic tumor have obviously improved under the inhibitory effect of angiostatin, which are consistent with physiological observed facts. The simulation results may provide beneficial information and theoretical models for clinical research of anti-angiogenic therapy strategies. [ABSTRACT FROM AUTHOR]

Purpose: Angiostatin and angiostatin-like molecules are known as anti-angiogenic factors, which inhibit endothelial cell functions resulting in reduced tumour growth. Recent data indicate that these molecules, especially PlgK1-5, directly affect tumour cells, which could explain the strong anti-tumoural effects of PlgK1-5. Therefore, we have analysed whether PlgK1-5 alters tumour cell functions and expression levels of cell adhesion molecules in murine and human hepatoma cells in vitro and in vivo. Methods: First, effects on tumour growth, proliferation and apoptosis were investigated in vivo in a subcutaneous tumour model. In vitro, effects of PlgK1-5 on tumour cell apoptosis, clonal expansion, migration, corresponding ICAM expression and intracellular signal transduction in murine Hepa129 and human HuH7 hepatoma cells have been analysed. Results: In vivo, subcutaneous tumour growth was reduced by 75% in PlgK1-5-treated animals compared to the controls. This was accompanied by increased tumour cell apoptosis (up to 33%) and decreased tumour cell proliferation (by up to 21%). In vitro, PlgK1-5 induced apoptosis in hepatoma cells, corresponding to increased caspase-8 cleavage and reduced AKT phosphorylation. Migration and clonal expansion was also diminished in PlgK1-5-treated Hepa129, corresponding to decreased ICAM expression levels. Conclusions: Here, we show that PlgK1-5 directly affects tumour cells by decreasing cell adhesion resulting-at least partly-in apoptosis. This is mediated by altered intracellular signal transduction and by activation of the caspase cascade. These findings further underscore the potential therapeutic role of PlgK1-5 in the treatment of HCC. [ABSTRACT FROM AUTHOR]

Diseases complicated by abnormal growth of vessels or excessive leakage are the most prevalent cause of moderate or severe vision loss in developed countries. Recent progress unraveling the molecular pathogenesis of several of these disease processes has led to new drug therapies that have provided major benefits to patients. However, those treatments often require frequent intraocular injections, and despite monthly injections, some patients have a suboptimal response. Gene transfer of antiangiogenic proteins is an alternative approach that has the potential to provide long-term suppression of neovascularization (NV) and/or excessive vascular leakage in the eye. Studies in animal models of ocular NV have demonstrated impressive results with a number of transgenes, and a clinical trial in patients with advanced neovascular age-related macular degeneration has provided proof-of-concept. Two ongoing clinical trials, one using an adeno-associated viral (AAV) vector to express a vascular endothelial growth factor-binding protein and another using a lentiviral vector to express endostatin and angiostatin, will provide valuable information that should help to inform future trials and provide a foundation on which to build. [ABSTRACT FROM AUTHOR]

α1(IV)NC1 inhibits angiogenesis by regulating MAPK activation, this biological function was partly attributed α1(IV)NC1 binding to α1β1-integrin. However, its potent antiangiogenic activity and the molecular targets of α1(IV)NC1 has not been investigated. In the present study, the regulation of MMP-2 activation by α1(IV)NC1 was evaluated. α1β1-integrin which is required for inhibition of angiogenesis is not playing a role in cellular invasion and inhibition of MMP-2 activation by α1(IV)NC1. We found that α1(IV)NC1 binds the CBD of MMP-2 and forming a stable complex that prevents activation of MMP-2. The antiangiogenic activity of α1(IV)NC1 is mediated, in part, by this binding activity. In addition, up-regulation of TIMP-2 by α1(IV)NC1 led to saturation of MT1-MMP binding sites, which in turn led to inhibition of MMP-2 activation. In-vivo studies using α1-integrin null-mice treated with higher doses of α1(IV)NC1 showed integrin independent inhibition of tumor growth and active-MMP-2, without affecting MMP-9, MMP-7 and angiostatin. [ABSTRACT FROM AUTHOR]