A notch1 ectodomain construct inhibits endothelial notch signaling, tumor growth, and angiogenesis.
ABSTRACT Notch signaling is required for vascular development and tumor angiogenesis. Although inhibition of the Notch ligand Delta-like 4 can restrict tumor growth and disrupt neovasculature, the effect of inhibiting Notch receptor function on angiogenesis has yet to be defined. In this study, we generated a soluble form of the Notch1 receptor (Notch1 decoy) and assessed its effect on angiogenesis in vitro and in vivo. Notch1 decoy expression reduced signaling stimulated by the binding of three distinct Notch ligands to Notch1 and inhibited morphogenesis of endothelial cells overexpressing Notch4. Thus, Notch1 decoy functioned as an antagonist of ligand-dependent Notch signaling. In mice, Notch1 decoy also inhibited vascular endothelial growth factor-induced angiogenesis in skin, establishing a role for Notch receptor function in this process. We tested the effects of Notch1 decoy on tumor angiogenesis using two models: mouse mammary Mm5MT cells overexpressing fibroblast growth factor 4 (Mm5MT-FGF4) and NGP human neuroblastoma cells. Exogenously expressed FGF4 induced Notch ligand expression in Mm5MT cells and xenografts. Notch1 decoy expression did not affect tumorigenicity of Mm5MT-FGF4 cells in vitro but restricted Mm5MT-FGF4 xenograft growth in mice while markedly impairing neoangiogenesis. Similarly, Notch1 decoy expression did not affect NGP cells in vitro but disrupted vessels and decreased tumor viability in vivo. These results strongly suggest that Notch receptor signaling is required for tumor neoangiogenesis and provides a new target for tumor therapy.
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ABSTRACT: Notch is a critical regulator of angiogenesis and arterial specification. We show that ectopic expression of activated Notch1 induces endothelial morphogenesis in human umbilical vein endothelial cells (HUVEC) in a VEGFR-1-dependent manner. Notch1-mediated upregulation of VEGFR-1 in HUVEC increased their responsiveness to the VEGFR-1 specific ligand, Placental Growth Factor (PlGF). In mice and human endothelial cells, inhibition of Notch signaling resulted in decreased VEGFR-1 expression during VEGF-A-induced neovascularization. In summary, we show that Notch1 plays a role in endothelial cells by regulating VEGFR-1, a function that may be important for physiological and pathological angiogenesis.Journal of Angiogenesis Research 01/2010; 2(1):3.
Article: Notch modulates VEGF action in endothelial cells by inducing Matrix Metalloprotease activity.[show abstract] [hide abstract]
ABSTRACT: In the vasculature, Notch signaling functions as a downstream effecter of Vascular Endothelial Growth Factor (VEGF) signaling. VEGF regulates sprouting angiogenesis in part by inducing and activating matrix metalloproteases (MMPs). This study sought to determine if VEGF regulation of MMPs was mediated via Notch signaling and to determine how Notch regulation of MMPs influenced endothelial cell morphogenesis. We assessed the relationship between VEGF and Notch signaling in cultured human umbilical vein endothelial cells. Overexpression of VEGF-induced Notch4 and the Notch ligand, Dll4, activated Notch signaling, and altered endothelial cell morphology in a fashion similar to that induced by Notch activation. Expression of a secreted Notch antagonist (Notch1 decoy) suppressed VEGF-mediated activation of endothelial Notch signaling and endothelial morphogenesis. We demonstrate that Notch mediates VEGF-induced matrix metalloprotease activity via induction of MMP9 and MT1-MMP expression and activation of MMP2. Introduction of a MMP inhibitor blocked Notch-mediated endothelial morphogenesis. In mice, analysis of VEGF-induced dermal angiogenesis demonstrated that the Notch1 decoy reduced perivascular MMP9 expression. Taken together, our data demonstrate that Notch signaling can act downstream of VEGF signaling to regulate endothelial cell morphogenesis via induction and activation of specific MMPs. In a murine model of VEGF-induced dermal angiogenesis, Notch inhibition led to reduced MMP9 expression.Vascular cell. 01/2011; 3(1):2.
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ABSTRACT: ABSTRACT: Tumor angiogenesis is an important target for cancer therapy, with most current therapies designed to block the VEGF signaling pathway. However, clinical resistance to anti-VEGF therapy highlights the need for targeting additional tumor angiogenesis signaling pathways. The endothelial Notch ligand Dll4 (delta-like 4) has recently emerged as a critical regulator of tumor angiogenesis and thus as a promising new therapeutic anti-angiogenesis target. Blockade of Dll4-Notch signaling in tumors results in excessive, non-productive angiogenesis with resultant inhibitory effects on tumor growth, even in some tumors that are resistant to anti-VEGF therapies. As Dll4 inhibitors are entering clinical cancer trials, this review aims to provide current perspectives on the function of the Dll4-Notch signaling axis during tumor angiogenesis and as a target for anti-angiogenic cancer therapy.Vascular cell. 09/2011; 3(1):20.