The Experts below are selected from a list of 27330 Experts worldwide ranked by ideXlab platform
Masabumi Shibuya - One of the best experts on this subject based on the ideXlab platform.
-
VEGF receptor signal transduction.
Methods in Enzymology, 2008Co-Authors: Lena Claesson-welsh, Masabumi ShibuyaAbstract:Abstract Signal transduction by vascular endothelial growth factors (VEGFs) through their cognate VEGF receptor tyrosine kinases follows the consensus scheme for receptor tyrosine kinases. Thus, binding of ligand induces receptor dimerization and activation of the tyrosine kinase through transphosphorylation between receptor molecules, leading to initiation of intracellular signal transduction pathways. Certain signal transduction pathways are shared with most, if not all, receptor tyrosine kinases, whereas some may be unique (e.g., transduced only by VEGF Receptors). Indications that such unique signaling pathways may be discerned only when VEGF Receptors are expressed in their proper context (i.e., in endothelial cells of microcapillary origin). In this chapter, we describe a number of methods for the study of signal transduction in endothelial cells. We describe how to isolate and examine endothelial cell lines. We also describe the embryoid body model representing vasculogenesis and angiogenesis, the procedure for subcutaneous Matrigel plugs, and, finally, how to construct gene‐targeted mouse models. We emphasize the need for validation of in vitro data in more complex models, where endothelial cells reside in their proper three‐dimensional context.
-
signal transduction by VEGF Receptors in regulation of angiogenesis and lymphangiogenesis
Experimental Cell Research, 2006Co-Authors: Masabumi Shibuya, Lena ClaessonwelshAbstract:The VEGF/VPF (vascular endothelial growth factor/vascular permeability factor) ligands and Receptors are crucial regulators of vasculogenesis, angiogenesis, lymphangiogenesis and vascular permeability in vertebrates. VEGF-A, the prototype VEGF ligand, binds and activates two tyrosine kinase Receptors: VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). VEGFR1, which occurs in transmembrane and soluble forms, negatively regulates vasculogenesis and angiogenesis during early embryogenesis, but it also acts as a positive regulator of angiogenesis and inflammatory responses, playing a role in several human diseases such as rheumatoid arthritis and cancer. The soluble VEGFR1 is overexpressed in placenta in preeclampsia patients. VEGFR2 has critical functions in physiological and pathological angiogenesis through distinct signal transduction pathways regulating proliferation and migration of endothelial cells. VEGFR3, a receptor for the lymphatic growth factors VEGF-C and VEGF-D, but not for VEGF-A, regulates vascular and lymphatic endothelial cell function during embryogenesis. Loss-of-function variants of VEGFR3 have been identified in lymphedema. Formation of tumor lymphatics may be stimulated by tumor-produced VEGF-C, allowing increased spread of tumor metastases through the lymphatics. Mapping the signaling system of these important Receptors may provide the knowledge necessary to suppress specific signaling pathways in major human diseases.
-
properties of two VEGF Receptors flt 1 and kdr in signal transductiona
Annals of the New York Academy of Sciences, 2006Co-Authors: Yasufumi Sato, Shinichi Kanno, Nobuyuki Oda, Mayumi Abe, Mikito Ito, Kenya Shitara, Masabumi ShibuyaAbstract:Abstract: The properties of two VEGF Receptors, Flt-1 and KDR, in the signal transduction of VEGF in human umbilical vein endothelial cells (HUVECs) were investigated by using two newly developed blocking monoclonal antibodies (mAbs) against Flt-1 and KDR. VEGF stimulated the expression of transcription factor Ets-1 as well as matrix metalloproteinase-1 (MMP-1) and Flt-1 in HUVECs. The KDR/Flt-1 heterodimer and the KDR homodimer mediate the expression of Ets-1, MMP-1, and Flt-1. VEGF also stimulated DNA synthesis and migration of HUVECs. DNA synthesis is mediated by the same signaling system as the expression of Ets-1. In contrast, cell migration is regulated by two distinct signaling systems. The Flt-1 homodimer is required for actin reorganization. The KDR/Flt-1 heterodimer and the KDR homodimer are required for the assembly of vinculin in focal adhesion plaque by regulating the phosphorylation of focal adhesion kinase (FAK) and paxillin.
-
roles of two VEGF Receptors flt 1 and kdr in the signal transduction of VEGF effects in human vascular endothelial cells
Oncogene, 2000Co-Authors: Shinichi Kanno, Masabumi Shibuya, Nobuyuki Oda, Mayumi Abe, Mikito Ito, Kenya Shitara, Yoshito Terai, Koichi Tabayashi, Yasufumi SatoAbstract:Vascular endothelial growth factor (VEGF) is a principal regulator of vasculogenesis and angiogenesis. VEGF expresses its effects by binding to two VEGF Receptors, Flt-1 and KDR. However, properties of Flt-1 and KDR in the signal transduction of VEGF-mediated effects in endothelial cells (ECs) were not entirely clarified. We investigated this issue by using two newly developed blocking monoclonal antibodies (mAbs) against Flt-1 and KDR. VEGF elicits DNA synthesis and cell migration of human umbilical vein endothelial cells (HUVECs). The pattern of inhibition of these effects by two mAbs indicates that DNA synthesis is preferentially mediated by KDR. In contrast, the regulation of cell migration by VEGF appears to be more complicated. Flt-1 regulates cell migration through modulating actin reorganization, which is essential for cell motility. A distinct signal is generated by KDR, which influences cell migration by regulating cell adhesion via the assembly of vinculin in focal adhesion plaque and tyrosine-phosphorylation of focal adhesion kinase (FAK) and paxillin.
-
VEGF121, a vascular endothelial growth factor (VEGF) isoform lacking heparin binding ability, requires cell-surface heparan sulfates for efficient binding to the VEGF Receptors of human melanoma cells
Journal of Biological Chemistry, 1995Co-Authors: Tzafra Cohen, Hela Gitay-goren, Rivka Sharon, Masabumi Shibuya, R. Halaban, Ben-zion Levi, Gera NeufeldAbstract:Abstract Four vascular endothelial growth factor (VEGF) splice variants containing 121, 165, 189, and 206 amino acids are produced from a single human gene as a result of alternative splicing. VEGF121 is not a heparin-binding protein, while the other VEGF species possess heparin binding ability. YU-ZAZ6 human melanoma cells expressed the mRNA encoding the VEGF receptor flt-1, but not the mRNA encoding the VEGF receptor KDR/flk-1. Both VEGF121 and VEGF165 bound to the VEGF Receptors of these cells. Unexpectedly, heparin inhibited the binding of VEGF121 as well as the binding of VEGF165 to the VEGF Receptors of the melanoma cells. Digestion of the cells with heparinase also inhibited the binding of both VEGF variants. The VEGF165 binding ability of heparinase-digested cells could be partially restored by the addition of exogenous heparin to the binding reaction. In contrast, the addition of heparin to heparinase-digested cells did not restore VEGF121 binding. These results suggest that cell-surface heparan sulfates may regulate the binding ability of the VEGF Receptors of the melanoma cells. They also indicate that heparin is not able to fully substitute for cell surface-associated heparan sulfates since VEGF121 binding to the VEGF Receptors of heparinase-treated cells is not restored by heparin. These data suggest that changes in the composition of cell-surface heparin-like molecules may differentially affect the interaction of various VEGF isoforms with VEGF Receptors.
Gera Neufeld - One of the best experts on this subject based on the ideXlab platform.
-
the neuropilins multifunctional semaphorin and VEGF Receptors that modulate axon guidance and angiogenesis
Trends in Cardiovascular Medicine, 2002Co-Authors: Gera NeufeldAbstract:The neuropilin-1 (np1) and neuropilin-2 (np2) Receptors function as Receptors for the axon guidance factors belonging to the class-3 semaphorin subfamily. In addition, both neuropilins are able to bind to certain heparin-binding splice forms of vascular endothelial growth factor (VEGF), indicating that both neuropilins have roles in the cardiovascular system as well. Gene targeting experiments indicate that np1 does indeed function as an important modulator of VEGF function during vasculogenesis and angiogenesis, but the role of np2 in the cardiovascular system has not been studied in detail as yet. This review focuses on the neuropilins, their interactions, and their biological roles in the nervous and cardiovascular systems.
-
characterization of novel vascular endothelial growth factor VEGF Receptors on tumor cells that bind VEGF via its exon 7 encoded domain
Journal of Biological Chemistry, 1996Co-Authors: Shay Soker, Gera Neufeld, Herman Fidder, Michael KlagsbrunAbstract:Vascular endothelial growth factor (VEGF), a potent angiogenic factor, uses two receptor tyrosine kinases, FLK/KDR and FLT, to mediate its activities. We have cross-linked 125I-VEGF165 to the cell surface of various tumor cell lines and of human umbilical vein endothelial cells. High molecular mass (220 and 240 kDa) and/or lower molecular mass (165 and 175 kDa) labeled complexes were detected depending on the cell type. The 220- and 240-kDa labeled complexes were shown to contain FLT and FLK/KDR Receptors, respectively. On the other hand, the 165- and 175-kDa complexes did not seem to contain FLK/KDR or FLT but instead appeared to contain novel VEGF Receptors with relatively low molecular masses of approximately 120 and 130 kDa. These Receptors were further characterized in breast cancer MDA MB 231 cells (231), which did not form the high molecular mass complexes and which did not express detectable amounts of flk/kdr or flt mRNA. The 231 cells displayed one VEGF165 binding site, with a Kd of 2.8 x 10(-10) M and 0.95 1.1 x 10(5) binding sites per cell. By comparison, human umbilical vein endothelial cells had two binding sites, one with a Kd of 7.5 x 10(-12) M, presumably FLK/KDR, and the other with a Kd of 2 x 10(-10) M, a value similar to the VEGF binding sites on 231 cells. These lower affinity/molecular mass Receptors on 231 cells cross-linked 125I-VEGF165 but not 125I-VEGF121. Accordingly, exon 7 of VEGF, which encodes the 44 amino acids present in VEGF165 that are absent in VEGF121, was fused to glutathione S-transferase (GST). The GST-VEGF-exon 7 fusion protein bound to heparin-Sepharose with a similar affinity as VEGF165 and inhibited the binding of 125I-VEGF165 to 231 cells. Cross-linking of 125I-GST-VEGF-exon 7 to 231 cells resulted in the formation of 150- and 160-kDa labeled complexes that presumably contained the 120- and 130-kDa lower affinity/molecular mass VEGF165 Receptors. It was concluded that certain tumor-derived cell lines express novel surface-associated Receptors that selectively bind VEGF165 via the exon 7-encoded domain, which is absent in VEGF121.
-
selective binding of VEGF to one of the three vascular endothelial growth factor Receptors of vascular endothelial cells
Journal of Biological Chemistry, 1996Co-Authors: Hela Gitaygoren, Tzafra Cohen, Ben-zion Levi, Shay Soker, Michael Klagsbrun, Shoshana Tessler, Stela Gengrinovitch, Patricia Rockwell, Gera NeufeldAbstract:Abstract VEGF and VEGF are vascular endothelial growth factor splice variants that promote the proliferation of endothelial cells and angiogenesis. VEGF contains the 44 additional amino acids encoded by exon 7 of the VEGF gene. These amino acids confer upon VEGF a heparin binding capability which VEGF lacks. I-VEGF bound to three vascular endothelial growth factor (VEGF) Receptors on endothelial cells, while I-VEGF bound selectively only to the flk-1 VEGF receptor which corresponds to the larger of the three VEGF Receptors. The binding of I-VEGF to flk-1 was not affected by the removal of cell surface heparan sulfates or by heparin. Both VEGF and VEGF inhibited the binding of I-VEGF to a soluble extracellular domain of the flk-1 VEGF receptor in the absence of heparin. However, heparin potentiated the inhibitory effect of VEGF by 2-3-fold. These results contrast with previous observations which have indicated that the binding of I-VEGF to the flk-1 receptor is strongly dependent on heparin-like molecules. Further experiments showed that the receptor binding ability of VEGF is susceptible to oxidative damage caused by oxidants such as HO or chloramine-T. VEGF was also damaged by oxidants but to a lesser extent. Heparin or cell surface heparan sulfates restored the flk-1 binding ability of damaged VEGF but not the receptor binding ability of damaged VEGF. These observations suggest that alternative splicing can generate a diversity in growth factor signaling by determining receptor recognition patterns. They also indicate that the heparin binding ability of VEGF may enable the restoration of damaged VEGF function in processes such as inflammation or wound healing.
-
VEGF121, a vascular endothelial growth factor (VEGF) isoform lacking heparin binding ability, requires cell-surface heparan sulfates for efficient binding to the VEGF Receptors of human melanoma cells
Journal of Biological Chemistry, 1995Co-Authors: Tzafra Cohen, Hela Gitay-goren, Rivka Sharon, Masabumi Shibuya, R. Halaban, Ben-zion Levi, Gera NeufeldAbstract:Abstract Four vascular endothelial growth factor (VEGF) splice variants containing 121, 165, 189, and 206 amino acids are produced from a single human gene as a result of alternative splicing. VEGF121 is not a heparin-binding protein, while the other VEGF species possess heparin binding ability. YU-ZAZ6 human melanoma cells expressed the mRNA encoding the VEGF receptor flt-1, but not the mRNA encoding the VEGF receptor KDR/flk-1. Both VEGF121 and VEGF165 bound to the VEGF Receptors of these cells. Unexpectedly, heparin inhibited the binding of VEGF121 as well as the binding of VEGF165 to the VEGF Receptors of the melanoma cells. Digestion of the cells with heparinase also inhibited the binding of both VEGF variants. The VEGF165 binding ability of heparinase-digested cells could be partially restored by the addition of exogenous heparin to the binding reaction. In contrast, the addition of heparin to heparinase-digested cells did not restore VEGF121 binding. These results suggest that cell-surface heparan sulfates may regulate the binding ability of the VEGF Receptors of the melanoma cells. They also indicate that heparin is not able to fully substitute for cell surface-associated heparan sulfates since VEGF121 binding to the VEGF Receptors of heparinase-treated cells is not restored by heparin. These data suggest that changes in the composition of cell-surface heparin-like molecules may differentially affect the interaction of various VEGF isoforms with VEGF Receptors.
-
patterns of expression of vascular endothelial growth factor VEGF and VEGF Receptors in mice suggest a role in hormonally regulated angiogenesis
Journal of Clinical Investigation, 1993Co-Authors: Dorit Shweiki, Gera Neufeld, Ahuva Itin, Hela Gitaygoren, Eli KeshetAbstract:Vascular endothelial growth factor (VEGF) is a secreted endothelial cell-specific mitogen. To evaluate whether VEGF may play a role in angiogenesis, we have determined the spatial and temporal patterns of expression of VEGF and VEGF Receptors during natural angiogenic processes taking place within the female reproductive system. Four angiogenic processes were analyzed: neovascularization of ovarian follicles, neovascularization of the corpus luteum, repair of endometrial vessels, and angiogenesis in embryonic implantation sites. During all processes, VEGF mRNA was found to be expressed in cells surrounding the expanding vasculature. VEGF was predominantly produced in tissues that acquire new capillary networks (theca layers, lutein cells, endometrial stroma, and the maternal decidua, respectively). VEGF-binding activity, on the other hand, was found on endothelial cells of both quiescent and proliferating blood vessels. These findings are consistent with a role for VEGF in the targeting of angiogenic responses to specific areas. Using in situ hybridization, we show that VEGF is expressed in 10 different steroidogenic and/or steroid-responsive cell types (theca, cumulus, granulosa, lutein, oviductal epithelium, endometrial stroma, decidua, giant trophoblast cells, adrenal cortex, and Leydig cells). Furthermore, in some cells upregulation of VEGF expression is concurrent with the acquisition of steroidogenic activity, and expression in other cell types is restricted to a particular stage of the ovarian cycle. These findings suggest that expression of VEGF is hormonally regulated. We propose that excessive expression of VEGF during gonadotropin-induced ovulation may contribute to the development of ovarian hyperstimulation syndromes by virtue of the vascular permeabilization activity of this factor.
Herbert A Weich - One of the best experts on this subject based on the ideXlab platform.
-
Soluble VEGF Receptors.
Angiogenesis, 1999Co-Authors: Carsten Hornig, Herbert A WeichAbstract:The three human VEGF Receptors 1–3 mediate biological signals important for new blood vessel formation and lymphangiogenesis. Soluble VEGF Receptors contain all the information necessary for high affinity ligand binding and have been used as experimental tools and regulators in several angiogenic in vitro and in vivo models. Recombinant receptor molecules can be used for specific inhibition of VEGF mediated signal transduction and for blocking tumor angiogenesis by limiting the amount of VEGF secreted from tumor cells or stroma cells. A naturally occurring soluble VEGFR-1 has been discovered in the supernatant from endothelial cells and at present appears to be the key regulator for the availability of VEGF secreted from different cells and tissues. The exact physiological role has not yet been demonstrated.
-
differential binding characteristics and cellular inhibition by soluble VEGF Receptors 1 and 2
Experimental Cell Research, 1998Co-Authors: Wolfgang Roeckl, Johannes Waltenberger, Avner Yayon, Dalit Hecht, Helena Sztajer, Herbert A WeichAbstract:The FLT-1 and KDR genes encode transmembrane tyrosine kinases which function as high-affinity Receptors for vascular endothelial growth factor (VEGF). We have used the baculovirus system to express the extracellular parts of the FLT-1 receptor and KDR receptor in soluble form (sFLT-1 and sKDR), forin vitrobinding and competition assays. Here, we show that the binding of VEGF165to sKDR but not sFLT-1 is dependent on heparin, regardless of whether VEGF165or sKDR is immobilized. Further, only sFLT-1 acts as a receptor antagonist in solution and sKDR can neither compete with the binding of VEGF165to human endothelial cells carrying both Receptors nor block VEGF165induced mitogenicity. Soluble KDR only partially inhibits cell migration even at high concentrations, in contrast to sFLT which can almost completely block (82%) VEGF-induced cell proliferation and migration. Taken together these results show that the two soluble VEGF receptor proteins, sFLT-1 and sKDR, despite binding the same ligand, behave very differently when immobilized with regard to their dependence on heparin for VEGF binding. In solution their respective ability to function as receptor antagonists is also strikingly different, possibly a reflection of their different dependency on heparin.
-
vascular endothelial growth factor and glioma angiogenesis coordinate induction of VEGF Receptors distribution of VEGF protein and possible in vivo regulatory mechanisms
International Journal of Cancer, 1994Co-Authors: Karl-heinz Plate, Georg Breier, Hans Dieter Mennel, Herbert A Weich, Werner RisauAbstract:We have previously suggested that tumor angiogenesis in human gliomas is regulated by a paracrine mechanism involving vascular endothelial growth factor (VEGF) and flt-I (VEGF-receptor I). VEGF, an endothelial-cell-specific mitogen, is abundantly expressed in glioma cells which reside along necrotic areas, whereas fit-I, a tyrosine-kinase receptor for VEGF, is expressed in tumor endothelial cells, but not in endothelial cells in normal adult brain. Recently, a second tyrosine-kinase receptor which binds VEGF with high affinity, designated KDR or flk-I, has been described. We performed in situ hybridization for VEGF mRNA, flt-I mRNA and KDR mRNA on serial sections of normal brain, low-grade and high-grade glioma specimens. We show that KDR mRNA is co-expressed with flt-I in vascular cells in glioblastoma but not in low-grade glioma. Since flt-I and KDR are not expressed in endothelial cells in the normal adult brain, the coordinate up-regulation of 2 Receptors for VEGF appears to be a critical event which controls tumor angiogenesis. Immunocytochemistry with a monoclonal anti-VEGF antibody revealed significant amounts of VEGF protein in the same glioma cells that expressed VEGF mRNA. The largest amount of VEGF immunoreactivity, however, was detected on the vasculature of glioblastomas, the site where VEGF exerts its biological functions. These findings suggest that VEGF is produced and secreted by glioma cells and acts on tumor endothelial cells which express VEGF Receptors. To further characterize VEGF-producer cells in vivo, we investigated cellular proliferation, immunoreactivity to the p53 tumor-suppressor gene product and epidermal-growth-factor-receptor(EGFR) expression on serial sections by immunocytochemistry. VEGF-producer cells did not show increased cellular proliferation, p53 immunoreactivity or EGFR immunoreactivity as compared with glioma cells which did not express VEGF. Our studies therefore do not demonstrate evidence for a growth advantage of VEGF-producer cells in vivo or VEGF induction by p53 mutation or EGFR over-expression. © 1994 Wiley-Liss, Inc.
-
differential expression of the two VEGF Receptors flt and kdr in placenta and vascular endothelial cells
Journal of Cellular Biochemistry, 1994Co-Authors: Bernhard Barleon, Stefanie Hauser, Claudia Schollmann, Karin Weindel, Dieter Marme, Avner Yayon, Herbert A WeichAbstract:Vascular endothelial growth factor (VEGF) is a newly identified growth and permeability factor with a unique specificity for endothelial cells. Recently the flt-encoded tyrosine kinase was characterized as a receptor for VEGF. A novel tyrosine kinase receptor encoded by the KDR gene was also found to bind VEGF with high affinity when expressed in CMT-3 cells. Screening for flt and KDR expression in a variety of species and tissue-derived endothelial cells demonstrates that flt is predominantly expressed in human placenta and human vascular endothelial cells. Placenta growth factor (PIGF), a growth factor significantly related to VEGF, is coexpressed with flt in placenta and human vascular endothelial cells. KDR is more widely distributed and expressed in all vessel-derived endothelial cells. These data demonstrate that cultured human endothelial cells isolated from different tissues express both VEGF Receptors in relative high levels and, additionally, that all investigated nonhuman endothelial cells in culture are also positive for KDR gene expression.
Yasufumi Sato - One of the best experts on this subject based on the ideXlab platform.
-
properties of two VEGF Receptors flt 1 and kdr in signal transductiona
Annals of the New York Academy of Sciences, 2006Co-Authors: Yasufumi Sato, Shinichi Kanno, Nobuyuki Oda, Mayumi Abe, Mikito Ito, Kenya Shitara, Masabumi ShibuyaAbstract:Abstract: The properties of two VEGF Receptors, Flt-1 and KDR, in the signal transduction of VEGF in human umbilical vein endothelial cells (HUVECs) were investigated by using two newly developed blocking monoclonal antibodies (mAbs) against Flt-1 and KDR. VEGF stimulated the expression of transcription factor Ets-1 as well as matrix metalloproteinase-1 (MMP-1) and Flt-1 in HUVECs. The KDR/Flt-1 heterodimer and the KDR homodimer mediate the expression of Ets-1, MMP-1, and Flt-1. VEGF also stimulated DNA synthesis and migration of HUVECs. DNA synthesis is mediated by the same signaling system as the expression of Ets-1. In contrast, cell migration is regulated by two distinct signaling systems. The Flt-1 homodimer is required for actin reorganization. The KDR/Flt-1 heterodimer and the KDR homodimer are required for the assembly of vinculin in focal adhesion plaque by regulating the phosphorylation of focal adhesion kinase (FAK) and paxillin.
-
roles of two VEGF Receptors flt 1 and kdr in the signal transduction of VEGF effects in human vascular endothelial cells
Oncogene, 2000Co-Authors: Shinichi Kanno, Masabumi Shibuya, Nobuyuki Oda, Mayumi Abe, Mikito Ito, Kenya Shitara, Yoshito Terai, Koichi Tabayashi, Yasufumi SatoAbstract:Vascular endothelial growth factor (VEGF) is a principal regulator of vasculogenesis and angiogenesis. VEGF expresses its effects by binding to two VEGF Receptors, Flt-1 and KDR. However, properties of Flt-1 and KDR in the signal transduction of VEGF-mediated effects in endothelial cells (ECs) were not entirely clarified. We investigated this issue by using two newly developed blocking monoclonal antibodies (mAbs) against Flt-1 and KDR. VEGF elicits DNA synthesis and cell migration of human umbilical vein endothelial cells (HUVECs). The pattern of inhibition of these effects by two mAbs indicates that DNA synthesis is preferentially mediated by KDR. In contrast, the regulation of cell migration by VEGF appears to be more complicated. Flt-1 regulates cell migration through modulating actin reorganization, which is essential for cell motility. A distinct signal is generated by KDR, which influences cell migration by regulating cell adhesion via the assembly of vinculin in focal adhesion plaque and tyrosine-phosphorylation of focal adhesion kinase (FAK) and paxillin.
Wei Xu - One of the best experts on this subject based on the ideXlab platform.
-
inhibition of tumor cell growth invasion and metastasis by exel 2880 xl880 gsk1363089 a novel inhibitor of hgf and VEGF receptor tyrosine kinases
Cancer Research, 2009Co-Authors: Fawn Qian, Stefan Engst, Kyoko Yamaguchi, Lillian Mock, Peiwen Yu, C Li, J Lougheed, F M Yakes, Frauke Bentzien, Wei XuAbstract:The Met receptor tyrosine kinase and its ligand, hepatocyte growth factor (HGF), are overexpressed and/or activated in a wide variety of human malignancies. Vascular endothelial growth factor (VEGF) Receptors are expressed on the surface of vascular endothelial cells and cooperate with Met to induce tumor invasion and vascularization. EXEL-2880 (XL880, GSK1363089) is a small-molecule kinase inhibitor that targets members of the HGF and VEGF receptor tyrosine kinase families, with additional inhibitory activity toward KIT, Flt-3, platelet-derived growth factor receptor β, and Tie-2. Binding of EXEL-2880 to Met and VEGF receptor 2 (KDR) is characterized by a very slow off-rate, consistent with X-ray crystallographic data showing that the inhibitor is deeply bound in the Met kinase active site cleft. EXEL-2880 inhibits cellular HGF-induced Met phosphorylation and VEGF-induced extracellular signal-regulated kinase phosphorylation and prevents both HGF-induced responses of tumor cells and HGF/VEGF-induced responses of endothelial cells. In addition, EXEL-2880 prevents anchorage-independent proliferation of tumor cells under both normoxic and hypoxic conditions. In vivo, these effects produce significant dose-dependent inhibition of tumor burden in an experimental model of lung metastasis. Collectively, these data indicate that EXEL-2880 may prevent tumor growth through a direct effect on tumor cell proliferation and by inhibition of invasion and angiogenesis mediated by HGF and VEGF Receptors. [Cancer Res 2009;69(20):8009–16]