Abstract 23: Microrna302-367 Sphingosine 1 Phosphate Receptor 1 Pathway Prevents Tumor Growth Via Restricting Angiogenesis and Enhancing Vascular Stability

Angiogenic hypersprouting and leaky immature vessels of pathological angiogenesis are essential for tumor growth. MicroRNAs have unique therapeutic advantages by targeting multiple pathways of tumor-associated angiogenesis, but the function of individual miRNAs in angiogenesis and tumors has not yet been fully evaluated. Here, we show that miR302-367 elevation in endothelial cells reduces retina sprouting angiogenesis and promotes vascular stability in vivo, ex vivo and in vitro. Erk1/2 are identified as direct targets of miR302-367, and down-regulation of Erk1/2 upon miR302-367 elevation in endothelial cells increases the expression of Klf2 and in turn S1pr1 and its downstream target VE-cadherin, suppressing angiogenesis and improving vascular stability. Conversely, both pharmacological blockade and genetic deletion of S1pr1 in endothelial cells reverse the anti-angiogenic and vascular stabilizing effect of miR302-367 in mice. Pathological angiogenesis in tumors shares features of developmental angiogenesis, and endothelial specific elevation of miR302-367 reduces tumor growth by restricting sprout angiogenesis and decreasing vascular permeability via the same Erk1/2-Klf2-S1pr1 pathways. In conclusion, miR302-367 regulation of an Erk1/2-Klf2-S1pr1 pathway in the endothelium advances our understanding of angiogenesis, meanwhile also provides opportunities for therapeutic intervention of tumor growth.