Abstract 5657: uPAR-mediated endothelial targeting facilitates endothelial to tumor cell transfer of oncolytic measles virus: In vitro and in vivo studies.
Authors: Jing Yuqi , Kovacs Krisztina , Merchan Jaime R. 
Published: August 2012

Abstract
The tumor endothelium constitutes a barrier to the efficient delivery of viral and non-viral therapeutic agents into tumor cells after systemic administration. Because endothelial cells are easily accessible after intravenous administration of a therapeutic agent, oncolytic viruses that target tumor endothelium may have the advantage of circumventing this problem since they may bind to endothelial cells, replicate in them, and facilitate viral entry into tumor tissue. The urokinase plasminogen receptor (uPAR) is over-expressed in tumor endothelium and plays a critical role in tumor neovascularization. The goal of this study is to demonstrate the ability of an oncolytic measles virus redirected against uPAR (MV-uPA) to infect endothelial cells in vitro and to target tumor vasculature in vivo. We engineered and rescued recombinant oncolytic measles viruses fully retargeted against human (MV-huPA) or murine (MV-muPA) urokinase receptor. A dual targeting measles virus (MV-un-muPA, targeting human cancer cells via CD46 and murine tissues via murine uPAR) was generated by displaying murine ATF of uPA into the C-terminus of the unmodified MV-H glycoprotein of MV-Edm genome, and then rescued. The specific dual species targeting virus offers the unique opportunity to investigate the ability of a virus to target tumor angiogenesis (via murine uPAR) and deliver the infection to tumor cells (via CD46) in vivo. Stimulation of human (HUVEC, HMVEC-L and HMVEC-D) and murine (MS1) endothelial cells by serum and growth factors was associated with upregulation of uPAR expression, as compared to non-stimulated ECs, while levels of CD46 -the natural receptor for non-retargeted oncolytic MV-were not changed. Upregulation of uPAR was associated with higher infection efficiency of ECs by the species specific MV-uPA compared to non-targeted MV-GFP. Human endothelial (EC)-to-human tumor cell (TC) viral transfer in vitro was demonstrated by co-culture experiments between MV-huPA infected ECs expressing GFP and uninfected, RFP expressing breast cancer cells (MDA-MB-231, MDA-MB-436, MCF-7) and identification of yellow fluorescent syncytia. MV-un-muPA efficiently infected mouse ECs (MS1) and human cancer cells. Importantly, MS-1 cells infected with MV-un-muPA successfully transferred the virus to human TCs. Intravenous administration of MV-un-muPA to mice bearing human breast tumors (MDA-MB-231) was associated with targeting of murine tumor vasculature (via murine uPAR), higher viral protein (MV-N) in tumor tissues, and a trend to better survival, compared with single targeted (CD46) control virus, In conclusion, our results demonstrated that tumor endothelial uPAR targeting by MV-uPA facilitates endothelial-to tumor cell viral transfer in vitro, and viral entry into tumor tissues in vivo by targeting angiogenic endothelium.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5657. doi:1538-7445.AM2012-5657