Endothelial-Specific Notch Blockade Inhibits Vascular Function and Tumor Growth through an eNOS-Dependent Mechanism

Abstract

Notch signaling is important for tumor angiogenesis induced by vascular endothelial growth factor A. Blockade of the Notch ligand Dll4 inhibits tumor growth in a paradoxical way. Dll4 inhibition increases endothelial cell sprouting, but vessels show reduced perfusion. The reason for this lack of perfusion is not currently understood. Here we report that inhibition of Notch signaling in endothelial cell using an inducible binary transgenic system limits VEGFAdriven tumor growth and causes endothelial dysfunction. Neither excessive endothelial cell sprouting nor defects of pericyte abundance accompanied the inhibition of tumor growth and functional vasculature. However, biochemical and functional analysis revealed that endothelial nitric oxide production is decreased by Notch inhibition. Treatment with the soluble guanylate cyclase activator BAY41-2272, a vasorelaxing agent that acts downstream of endothelial nitric oxide synthase (eNOS) by directly activating its soluble guanylyl cyclase receptor, rescued blood vessel function and tumor growth. We show that reduction in nitric oxide signaling is an early alteration induced by Notch inhibition and suggest that lack of functional vessels observed with Notch inhibition is secondary to inhibition of nitric oxide signaling. Coculture and tumor growth assays reveal that Notch-mediated nitric oxide production in endothelial cell requires VEGFA signaling. Together, our data support that eNOS inhibition is responsible for the tumor growth and vascular function defects induced by endothelial Notch inhibition. This study uncovers a novel mechanism of nitric oxide production in endothelial cells in tumors, with implications for understanding the peculiar character of tumor blood vessels. Cancer Res; 74(9); 2402-11. Ó2014 AACR.

Transdifferentiated Human Vascular Smooth Muscle Cells are a New Potential Cell Source for Endothelial Regeneration

“…7b,c). Interestingly, previous studies showed that JAG1 stimulation could activate eNOS in the presence of VEGF 38 . In our system, we observed that eNOS promoter was activated by JAG1 overexpression (Fig.…”

“…JAG1 is the upstream ligand of the Notch pathway and serves a much more complicated context-dependent role in regulating vascular activities 37, 38 . Upon recombinant JAG1 stimulation during differentiation, part of the endothelial markers, especially eNOS, could be induced to a higher level (Fig.…”

Mechanism of melanoma cells selective apoptosis induced by a photoactive NADPH analogue

“…NO produced by the NO-synthases may act as a pro-angiogenic factor in many cancers. Both endothelial and neuronal NO-synthases have been linked with metastasis [12] and modulation of several signaling pathways active in melanoma as Notch and Interferon [13]. Melanoma-cell derived NO is a crucial modulator of immune function in the tumor microenvironment and provides a potentially novel target for treatment [14].…”

Protein Kinases and Associated Pathways in Pluripotent State and Lineage Differentiation

“…In addition, biochemical and functional analysis reveals that endothelial nitric oxide production is decreased by Notch inhibition, suggesting that lack of functional vessels observed with Notch inhibition is secondary to inhibition of nitric oxide signaling. Co-culture and tumor growth assays reveal that Notch-mediated nitric oxide production in ECs requires VEGFA signaling [320]. …”