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Query: UMLS:C0598934 (tumor growth)
 58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Current research on angiogenesis and vascular regression is mainly focused on pathological conditions such as tumor growth and diabetic retinopathy, while a suitable physiological model to study the controlling factors in these processes is still lacking. The remodeling pattern of the embryonic vasculature into the adult configuration, such as the branchial arch arterial system developing into the aorta or the early embryonic veins building the caudal vena cava can potentially serve as a model. However, practical applications of the embryonic vascular patterning are impeded by the current controversy over the exact development of the caudal vena cava in mammals. To elucidate these ambiguities, specific developmental stages of vascular development in pig embryos were mapped by means of computer-assisted 3D reconstructions starting from histological serial sections of Bouin's fixed embryos. Special attention was given to venous segments in the lumbar region, as their origin and fate are equivocally described in literature. Here we demonstrate that these venous segments originate from the caudal cardinal veins which are forced to migrate during development into a more dorsal position due to the expansion of the developing metanephroi and the more dorsal relocation of the umbilical arteries. These findings are in contrast with the generally accepted theory that the venous segments in the lumbar region arise from newly formed veins that are located dorsal to the early caudal cardinal system.
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PMID:Three-dimensional reconstruction of the remodeling of the systemic vasculature in early pig embryos. 1793 89

Angiogenesis means the formation of new blood vessels from preexisting vascular, is of fundamental importance in several pathological states such as tumor growth, rheumatoid arthritis, and diabetic retinopathy. Angiogenesis involves a set of steps, including activation and movement of endothelial cells and tube formation. Control of these steps by drugs or dietary food components is a hopeful approach for the prevention of angiogenic disorders. Based on these backgrounds, we searched the anti-angiogenic food components. As a result, we found that tocotrienol (T3), especially delta, beta, and gamma-T3 has the potent anti-angiogenic activity in vitro and in vivo experiments. T3, which is rich in rice bran and palm oil, inhibited growth factor-induced proliferation, migration and tube formation in human umbilical vein endothelial cells. T3 showed inhibition of tumor cell-induced angiogenesis in mouse dorsal air sac (DOS) assay. These results indicated that T3 is a potent anti-angiogenesis compound. Tocopherol (Toc) did not inhibit angiogenesis. The anti-angiogenic mechanism of T3 and Toc was evaluated by western blotting. T3 inhibited activation of growth factor-induced extracellular signal-regulated kinase, Akt (protein kinase B), and endothelial nitric oxide synthase (eNOS), which are located downstream of the various growth factor receptors. T3 suppressed phosphorylation of vascular endothelial growth factor (VEGF) receptor 2. These effects were dose-dependent manner. Anti-angiogenic mechanism of T3 mediates inhibition of growth factor induced survival, migration and angiogenesis signals. These findings suggested that T3 may have potential for preventing angiogenic disorders in humans.
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PMID:Anti-angiogenic function of tocotrienol. 1829 49

The anti-inflammatory nature of the intraocular environment is critical to the immune privilege of the eye. An important part of immune privilege is the induction of apoptosis by two death-inducing ligands (FasL and TRAIL) that can limit the spread of inflammation and control tumor growth. While initial studies focused on control of inflammation and the impact of these molecules on the systemic immune response, more recent studies have extended this concept to pathogenic neovascularization. This process is an important component of several blinding eye disorders including age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, and corneal disease. These studies showed that the mediators of immune privilege also regulate the extent of angiogenesis. In this article, we will develop the idea that constitutive expression of FasL in the eye, as well as inducible FasL on cells of the immune system, modulates neovascularization in ocular disease. Further, we will present the idea that macrophage participation in this process and their function during disease depends on the microenvironment and the cytokine milieu. These concepts challenge the idea that neovascular eye disease is simply an inflammatory process and support the idea that these diseases may result from the loss or dysfunction of important components of the cellular immune system.
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PMID:Angiogenesis in eye disease: immunity gained or immunity lost? 1829 88

Angiogenesis is associated with growth, invasion, and metastasis of human solid tumors. Aberrant activation of endothelial cells and induction of microvascular permeability by a vascular endothelial growth factor (VEGF) receptor-2 (VEGFR-2) signaling pathway is observed in pathological angiogenesis including tumor, wound healing, arthritis, psoriasis, diabetic retinopathy, and others. Here, we show that GM3 regulated the activity of various downstream signaling pathways and biological events through the inhibition of VEGF-stimulated VEGFR-2 activation in vascular endothelial cells in vitro. Furthermore, GM3 strongly blocked VEGF-induced neovascularization in vivo, in models including the chick chorioallantoic membrane and Matrigel plug assay. Interestingly, GM3 suppressed VEGF-induced VEGFR-2 activation by blocking its dimerization and also blocked the binding of VEGF to VEGFR-2 through a GM3-specific interaction with the extracellular domain of VEGFR-2, but not with VEGF. Primary tumor growth in mice was inhibited by subcutaneous injection of GM3. Immunohistochemical analyses showed GM3 inhibition of angiogenesis and tumor cell proliferation. GM3 also resulted in the suppression of VEGF-stimulated microvessel permeability in mouse skin capillaries. These results suggest that GM3 inhibits VEGFR-2-mediated changes in vascular endothelial cell function and angiogenesis, and might be of value in anti-angiogenic therapy.
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PMID:Ganglioside GM3 inhibits VEGF/VEGFR-2-mediated angiogenesis: direct interaction of GM3 with VEGFR-2. 1897

Angiogenesis is a general term describing formation of new tube-like microvessel sprouts that are the size of capillary blood vessels. Angiogenesis is fundamental in key stages of embryonic development, organ formation, and wound repair and is also involved in the development and progression of a variety of pathological conditions, including cancer (tumor growth and metastasis), cardiovascular disease, diabetic retinopathy, age-related macular degeneration, atherosclerosis, and rheumatoid arthritis. Because of its diverse roles in key physiological and pathological processes, angiogenesis is an important area of medical research, with a considerable number of angiogenic and anti-angiogenic drugs currently undergoing clinical trials. Cost-effective and efficient screening for potential lead compounds is therefore of prime importance. However, screening methodologies vary in their physiological relevance depending on how faithfully critical aspects of angiogenesis are represented. Cell-based in vitro angiogenesis assays are important tools for screening, which in many cases rely on imaging microscopy to ascertain drug effects. Unfortunately, such screens can be hampered by poorly defined biology, slow image acquisition by manual or semiautomated hardware, and slow data analysis by non-dedicated software. This article describes use of a 96-well microplate in vitro angiogenesis screening system as part of an integrated workflow, comprising (1) setting up the biology in a three-dimensional physiologically relevant system, (2) acquiring a series of image slices ("stacks") using an automated z-stage instrument, (3) collapsing the image stack series into sets of two-dimensional images, (4) segmenting objects of interest, and (5) analyzing the segmentation patterns in order to obtain statistically relevant data.
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PMID:Angiogenesis: an improved in vitro biological system and automated image-based workflow to aid identification and characterization of angiogenesis and angiogenic modulators. 1903 50

Mural cells are essential components of blood vessels and are necessary for normal development, homeostasis, and organ function. Alterations in mural cell density or the stable attachment of mural cells to the endothelium is associated with several human diseases such as diabetic retinopathy, venous malformation, and hereditary stroke. In addition mural cells are implicated in regulating tumor growth and have thus been suggested as potential antiangiogenic targets in tumor therapy. In recent years our knowledge of mural cell function and endothelial-mural cell signaling has increased dramatically, and we now begin to understand the mechanistic basis of the key signaling pathways involved. This is mainly thanks to sophisticated in vivo experiments using a broad repertoire of genetic technologies. In this review, we summarize the five currently best understood signaling pathways implicated in mural cell biology. We discuss PDGFB/PDGFRbeta- dependent pericyte recruitment, as well as the role of angiopoietins and Tie receptors in vascular maturation. In addition, we highlight the effects of sphingosine-1-phosphate signaling on adherens junction assembly and vascular stability, as well as the role of TGF-beta-signaling in mural cell differentiation. We further reflect recent data suggesting an important function for Notch3 signaling in mural cell maturation.
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PMID:Endothelial-mural cell signaling in vascular development and angiogenesis. 1916 13

Pathological ocular neovascularization, caused by diabetic retinopathy, age-related macular degeneration, or retinopathy of prematurity, is a leading cause of blindness, yet much remains to be learned about its underlying causes. Here we used oxygen-induced retinopathy (OIR) and laser-induced choroidal neovascularization (CNV) to assess the contribution of the metalloprotease-disintegrin ADAM9 to ocular neovascularization in mice. Pathological neovascularization in both the OIR and CNV models was significantly reduced in Adam9(-/-) mice compared to wild-type controls. In addition, the level of ADAM9 expression was strongly increased in endothelial cells in pathological vascular tufts in the OIR model. Moreover, tumor growth from heterotopically injected B16F0 melanoma cells was reduced in Adam9(-/-) mice compared to controls. In cell-based assays, the overexpression of ADAM9 enhanced the ectodomain shedding of EphB4, Tie-2, Flk-1, CD40, VCAM, and VE-cadherin, so the enhanced expression of ADAM9 could potentially affect pathological neovascularization by increasing the shedding of these and other membrane proteins from endothelial cells. Finally, we provide the first evidence for the upregulation of ADAM9-dependent shedding by reactive oxygen species, which in turn are known to play a critical role in OIR. Collectively, these results suggest that ADAM9 could be an attractive target for the prevention of proliferative retinopathies, CNV, and cancer.
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PMID:ADAM9 is involved in pathological retinal neovascularization. 1927 93

Angiogenesis is a necessary component of normal tissue repair, tumor growth and dissemination, and a wide variety of other inflammatory and pathological processes as well, including diabetic retinopathy, rheumatoid arthritis, and psoriasis. Consequently, the last two decades have seen extensive research into the regulation of neovascularization, particularly in tumors. Partly due to the emphasis on tumor angiogenesis, much of this effort has been devoted to the detection and characterization of angiogenic growth factors and inhibitory molecules. Thus assays have commonly been developed to measure the amount of vascular growth in vivo, or the modulation of endothelial cell (EC) proliferation, or migration in simple 2D culture systems (1).
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PMID:Rat Aortic Ring : 3D Model of Angiogenesis In Vitro. 2134 Sep 20

The endothelium is involved in a number of normal physiological processes (regulating circulating levels of vasoactive agents, blood/gas exchange, regulating cellular traffic between intavascular and extravascular compartments of tissues, maintenance of the blood brain barrier, and so forth) and pathophysiological conditions characterized either by increased angiogenesis (arthritis, diabetic retinopathy, atherosclerosis, tumor growth, and metastasis) or inadequate angiogenesis [failure of ulcers to heal (inadequate wound healing in general), myocardial infarction, limb ischaemia secondary to arterial occlusive diseases and others]. Its location immediately adjacent to the blood stream and the fact that it has a large surface area makes it an attractive target for genetransfer/gene-therapy strategies.
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PMID:Transfection and transduction of primary human endothelial cells. 2134 Sep 23

Neovessel formation is a complex process governed by the orchestrated action of multiple factors that regulate EC specification and dynamics within a growing vascular tree. These factors have been widely exploited to develop therapies for angiogenesis-related diseases such as diabetic retinopathy and tumor growth and metastasis. WNT signaling has been implicated in the regulation and development of the vascular system, but the detailed mechanism of this process remains unclear. Here, we report that Dickkopf1 (DKK1) and Dickkopf2 (DKK2), originally known as WNT antagonists, play opposite functional roles in regulating angiogenesis. DKK2 induced during EC morphogenesis promoted angiogenesis in cultured human endothelial cells and in in vivo assays using mice. Its structural homolog, DKK1, suppressed angiogenesis and was repressed upon induction of morphogenesis. Importantly, local injection of DKK2 protein significantly improved tissue repair, with enhanced neovascularization in animal models of both hind limb ischemia and myocardial infarction. We further showed that DKK2 stimulated filopodial dynamics and angiogenic sprouting of ECs via a signaling cascade involving LRP6-mediated APC/Asef2/Cdc42 activation. Thus, our findings demonstrate the distinct functions of DKK1 and DKK2 in controlling angiogenesis and suggest that DKK2 may be a viable therapeutic target in the treatment of ischemic vascular diseases.
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PMID:The WNT antagonist Dickkopf2 promotes angiogenesis in rodent and human endothelial cells. 2154 May 52


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