Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C1519670 (tumor angiogenesis)
6,052 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Receptor tyrosine kinases (RTKs) are a diverse group of transmembrane proteins involved in signal transduction. Their function in many cell types is to drive a wide variety of cellular functions, including growth, differentiation and angiogenesis, by transducing growth factor signals from the external milieu to intracellular processes. In malignancies, these pathways are often exploited by tumor cells to optimize tumor growth and metastasis. Indeed, alterations in RTK pathways have been implicated in oncogenic activation, tumor angiogenesis and mitogenic stimulation. Thus, RTKs are logical targets for novel anticancer agent development. There are currently a large number of small-molecule RTK antagonists in phase I to III clinical development. These agents inhibit the intracellular tyrosine kinase activity of receptors for epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF). The biology and results of clinical trials with these agents will be discussed.
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PMID:Receptor tyrosine kinase inhibitors. 1181 45

Angiogenesis, or the formation of new blood vessels from preexisting vasculature, plays a major role in tumor growth and metastasis formation. Therefore, inhibiting tumor angiogenesis may be a promising therapeutic strategy. Paracrine stimuli from tumor cells are the main promoters of angiogenesis. They activate endothelial cells to proliferate and migrate, subsequently resulting in new tube formation and blood flow. This complex process involves numerous biological activities. Vascular endothelial growth factor (VEGF) is a potent and specific angiogenic factor. Originally identified for its ability to induce vascular permeability and stimulate endothelial cell growth, VEGF is now known to be a key requirement for tumor growth. Currently, three high-affinity tyrosine kinase receptors for VEGF have been identified, of which VEGF receptor (VEGFR)-Flk-1/KDR (VEGFR-2) is exclusively expressed in vascular endothelial cells. Because the VEGFR-2 system is a dominant signal-transduction pathway in regulating tumor angiogenesis, specific inhibitors of this pathway inhibit metastases, microvessel formation, and tumor-cell proliferation. Induction of apoptosis in tumor cells and endothelial cells has also been observed. The clinical importance of VEGF for tumor growth is supported by the fact that most tumors produce VEGF and that the inhibition of VEGF-induced angiogenesis significantly inhibits tumor growth in vivo. In this review, we discuss the biologic role of VEGF and the therapeutic options for inhibiting VEGF in cancer patients.
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PMID:The role of vascular endothelial growth factor (VEGF) in tumor angiogenesis and early clinical development of VEGF-receptor kinase inhibitors. 1197 Jul 55

Epidermal growth factor receptor (EGFR) tyrosine kinase is a potential target for anticancer therapy. ZD1839 (Iressa) is a selective inhibitor of EGFR tyrosine kinase. In this study, we investigated the question as to whether the antitumor effect of ZD1839 is partly attributable to antiangiogenic activity and the potential mechanisms involved. Both ZD1839 and SU5416 [a vascular endothelial growth factor (VEGF)-receptor tyrosine kinase inhibitor] inhibited the migration of human umbilical vein endothelial cell cocultivated with EGF-stimulated cancer cells. ZD1839 also inhibited EGF-induced migration and the formation of tube-like structures by human microvascular endothelial cells. Moreover, ZD1839 almost completely blocked EGF-induced neovascularization of mice cornea, and SU5416 partially blocked neovascularization. In contrast, ZD1839 did not inhibit VEGF-induced angiogenesis. However, EGF-induced up-regulation of the angiogenic factors, VEGF and IL-8, was almost completely blocked by ZD1839. The antitumor effects of ZD1839 could, therefore, be mediated in part by the inhibition of tumor angiogenesis through direct effects on microvascular endothelial cells that express EGFR and also through reduced production of proangiogenic factors by tumor cells.
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PMID:ZD1839 (Iressa) induces antiangiogenic effects through inhibition of epidermal growth factor receptor tyrosine kinase. 1198 Jun 49

Interaction between vascular endothelial growth factor (VEGF) and its cognate receptors, KDR/Flk-1 and Flt-1, of vascular endothelial cells is expected to induce an angiogenesis "switch" in tumors and other angiogenesis-associated diseases. SU5416, a selective inhibitor of the KDR/Flk-1 tyrosine kinase, is known to be a potent inhibitor of tumor angiogenesis. In this study, we first observed that SU5416 inhibited Flt-1 tyrosine kinase activity at similar doses, in addition to inhibiting KDR/Flk-1 tyrosine kinase activity in response to VEGF. SU5416 inhibited cell migration of human vascular endothelial cells expressing both Flt-1 and KDR in response to VEGF and also inhibited the cell migration in response to placenta growth factor (PIGF), a specific ligand for Flt-1. Chemotaxis of monocytes expressing only Flt-1 was also inhibited by SU5416 in a dose-dependent manner. Moreover, SU5416 was found to inhibit tyrosine kinase of Flt-1 in response to PIGF in vitro. And angiogenesis induced by PIGF in a Matrigel plug assay was inhibited by administration of SU5416. The antiangiogenic effects by this VEGF receptor-targeting compound appeared to be mediated through interference not only with KDR/Flk-1 but also with Flt-1. Cell migration of vascular endothelial cells and monocytic cells through Flt-1, thus, might play a key role in VEGF-induced tumor angiogenesis in concert with KDR/Flk-1.
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PMID:Antiangiogenic effect by SU5416 is partly attributable to inhibition of Flt-1 receptor signaling. 1248 45

The purpose of this study was to evaluate the activity of the indolinone kinase inhibitor SU11248 against the receptor tyrosine kinase KIT in vitro and in vivo, examine the role of KIT in small cell lung cancer (SCLC), and anticipate clinical utility of SU11248 in SCLC. SU11248 is an oral, multitargeted tyrosine kinase inhibitor with direct antitumor and antiangiogenic activity through targeting platelet-derived growth factor receptor (PDGFR), vascular endothelial growth factor receptor, KIT, and FLT3 receptors. Treatment of the KIT-expressing SCLC-derived NCI-H526 cell line in vitro with SU11248 resulted in dose-dependent inhibition of stem cell factor-stimulated KIT phosphotyrosine levels and proliferation. The biological significance of KIT inhibition was evaluated in vivo by treating mice bearing s.c. NCI-H526 tumors with SU11248 or another structurally unrelated KIT inhibitor, STI571 (Gleevec), which is also known to inhibit Bcr-Abl and PDGFRbeta. SU11248 treatment resulted in significant tumor growth inhibition, whereas inhibition from STI571 treatment was less dramatic. Both compounds reduced phospho-KIT levels in NCI-H526 tumors, with a greater reduction by SU11248, correlating with efficacy. Likewise, phospho-PDGFRbeta levels contributed by tumor stroma and with known involvement in angiogenesis were strongly inhibited by SU11248 and less so by STI571. Because platinum-based chemotherapy is part of the standard of care for SCLC, SU11248 was combined with cisplatin, and significant tumor growth delay was measured compared with either agent alone. These results expand the profile of SU11248 as a KIT signaling inhibitor and suggest that SU11248 may have clinical potential in the treatment of SCLC via direct antitumor activity mediated via KIT as well as tumor angiogenesis via vascular endothelial growth factor receptor FLK1/KDR and PDGFRbeta.
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PMID:SU11248 inhibits KIT and platelet-derived growth factor receptor beta in preclinical models of human small cell lung cancer. 1274 9

Epidemiological and animal studies have indicated that consumption of green tea is associated with a reduced risk of developing certain forms of cancer. However, the inhibitory mechanism of green tea in angiogenesis, an important process in tumor growth, has not been well established. In the present study, green tea extract (GTE) was tested for its ability to inhibit cell viability, cell proliferation, cell cycle dynamics, vascular endothelial growth factor (VEGF) and expression of VEGF receptors fms-like tyrosine kinase (Flt-1) and fetal liver kinase-1/Kinase insert domain containing receptor (Flk-1/KDR) in vitro using human umbilical vein endothelial cells (HUVECs). GTE in culture media did not affect cell viability but significantly reduced cell proliferation dose-dependently and caused a dose-dependent accumulation of cells in the G1 phase. The decrease of the expression of Flt-1 and KDR/Flk-1 in HUVEC by GTE was detected with immunohistochemical and Western blotting methods. These results suggest that GTE may have preventive effects on tumor angiogenesis and metastasis through reduction of expression of VEGF receptors.
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PMID:Green tea extract inhibits angiogenesis of human umbilical vein endothelial cells through reduction of expression of VEGF receptors. 1285 Feb 45

Vascular endothelial growth factor A (VEGF-A) and its receptor tyrosine kinases located on endothelial cells seem to play an important role in the multistep pathway of angiogenesis. SU5416 is a small molecule which inhibits angiogenesis by acting as an inhibitor of VEGF receptor-2 tyrosine kinase. We have developed a reproducible murine model for neuroblastoma, a childhood cancer, based on s.c. xenotransplantation of SH-SY5Y neuroblastoma cells. We found that SH-SY5Y cells expressed VEGF-A on both the mRNA and protein levels, that plasma concentrations of VEGF-A were significantly elevated in animals with neuroblastoma with a volume > 1.4 ml, and that there was a correlation between VEGF-A levels in plasma and tumor size in untreated tumor-bearing animals. Treatment with SU5416 reduced the growth of neuroblastoma tumors by 65% without apparent toxicity. SU5416 treatment also suppressed tumor angiogenesis, despite an increase in plasma VEGF-A levels per ml tumor volume during therapy. Our experimental data suggest that the angiogenesis inhibitor SU5416 may be beneficial in the treatment of solid tumors of childhood such as neuroblastoma.
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PMID:Importance of vascular endothelial growth factor A in the progression of experimental neuroblastoma. 1290 18

Vascular endothelial growth factor (VEGF) is known to play a predominant role in tumor angiogenesis and metastasis formation that is mediated by its interactions with two tyrosine kinase receptors, VEGFRI (Flt-1) and VEGFRII (KDR). Inhibition of VEGF-dependent events in tumor tissues is known to enhance apoptosis and to suppress tumor growth. A novel peptide, SP5.2, which selectively binds Flt-1 and inhibits a broad range of VEGF-mediated events, was identified using a phage-display library screening. The fluorescein-labeled SP5.2 specifically bound to VEGF-stimulated primary human cerebral endothelial cells (HCECs), whereas non-stimulated HCECs, as well as human neuroblastoma cells (ShyY) did not show any interaction with the peptide. SP5.2 prevented proliferation of cultured primary human umbilical vein endothelial cells induced by recombinant human VEGF165 with an IC50 of 5 microm. SP5.2 was also shown to antagonize VEGF- and PLGF-induced, but not basic fibroblast growth factor-induced proliferation of HCECs. In contrast to "scrambled" peptide, SP5.2 was also found to selectively inhibit VEGF-stimulated migration of HCECs. The in vitro analysis of antiangiogenic activity of SP5.2 using a capillary-like tube formation assay showed that VEGF-induced angiogenesis of HCECs grown on Matrigel was completely inhibited in the presence of 10 microm SP5.2. Further studies demonstrated that SP5.2 prevented VEGF-induced permeability increase in HCECs monolayers. To explore whether SP5.2 can be used as a targeting agent, chemical and recombinant conjugates of SP5.2 with reporter proteins (peroxidase and beta-galactosidase) were produced. The resulting products showed significant increases (200-fold for SP5.2-beta-gal and 400-fold for SP5.2-peroxidase) in binding affinity to recombinant Flt-1 compared with the original synthetic SP5.2, suggesting that conjugate with therapeutic activity in nanomolar range could potentially be developed based on SP5.2 structure.
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PMID:A vascular endothelial growth factor high affinity receptor 1-specific peptide with antiangiogenic activity identified using a phage display peptide library. 1295 24

Vascular endothelial growth factor receptor-2 (VEGFR-2/KDR/Flk-1) is a high-affinity receptor for vascular endothelial growth factor-A (VEGF-A), and mediates most of the endothelial growth and survival signals from VEGF-A. VEGFR-2 has a typical tyrosine kinase receptor structure with seven immunoglobulin (Ig)-like domains in the extracellular region, as well as a long kinase insert in the tyrosine kinase domain. It utilizes a unique signaling system for DNA synthesis in vascular endothelial cells, i.e. a phospholipase C gamma-protein kinase C-Raf-MAP kinase pathway. Although VEGF-A binds two receptors, VEGFR-1 and -2, a newly isolated ligand VEGF-E (Orf-virus-derived VEGF) binds and activates only VEGFR-2. Transgenic mice expressing VEGF-E(NZ-7) showed a dramatic increase in angiogenesis with very few side effects (such as edema and hemorrhagic spots), suggesting strong angiogenic signaling and a potential clinical utility of VEGF-E. VEGF family members bear three loops produced via three intramolecular disulfide bonds, and cooperation between loop-1 and loop-3 is necessary for the specific binding and activation of VEGFR-2 for angiogenesis. As it directly upregulates tumor angiogenesis, VEGFR-2 is an appropriate target for suppression of solid tumor growth using exogenous antibodies, small inhibitory molecules and in vivo stimulation of the immune system.
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PMID:Vascular endothelial growth factor receptor-2: its unique signaling and specific ligand, VEGF-E. 1296 71

Perlecan is a major heparan sulfate proteoglycan (HSPG) of basement membranes (BMs) and connective tissues. The core protein of perlecan is divided into five domains based on sequence homology to other known proteins. Commonly, the N-terminal domain I of mammalian perlecan is substituted with three HS chains that can bind a number of matrix molecules, cytokines, and growth factors. Perlecan is essential for metazoan life, as shown by genetic manipulations of nematodes, insects, and mice. There are also known human mutations that can be lethal. In vertebrates, new functions of perlecan emerged with the acquisition of a closed vascular system and skeletal connective tissues. Many of perlecan's functions may be related to the binding and presentation of growth factors to high-affinity tyrosine kinase (TK) receptors. Data are accumulating, as discussed here, that similar growth factor-mediated processes may have unwanted promoting effects on tumor cell proliferation and tumor angiogenesis. Understanding of these attributes at the molecular level may offer opportunities for therapeutic intervention.
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PMID:Perlecan and tumor angiogenesis. 1456 13


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