BIOL-17. DISSECTING THE EXPRESSION AND FUNCTION OF ANGIOPOIETIN-1 IN PEDIATRIC BRAIN TUMORS

BACKGROUND: Angiopoietin-1 (Angpt1) is a secreted protein that promotes angiogenesis and vascular stability in development and certain disease states through activation of the Tie2 receptor. However, little is known about its expression or function within pediatric brain tumors. METHODS: We utilized available datasets from patient samples and created murine models of pediatric high-grade glioma and ependymoma by in utero electroporation. Using a combination of transcriptomics and Angpt1-GFP reporter tumor models we evaluated Angpt1 expression across different types of pediatric brain tumors. We also applied inducible Angpt1 floxed mice to generate tumor-specific knock-out models. RESULTS: Angpt1 is upregulated in glial brain tumors, including high-grade gliomas and ependymomas. We find Angpt1 is expressed by specific cell populations within gliomas and ependymomas, along with non-tumor reactive astrocytes and perivascular mural cells. Leveraging our in vivo brain tumor platform we have created tumor specific Angpt1 knock-out models by including a plasmid expressing Cre-recombinase. Ongoing studies aim to delineate the function of Angpt1 in tumor pathogenesis, including tumor angiogenesis and blood-brain barrier function. CONCLUSION: Current work finds that Angpt1 is upregulated in glial brain tumors and nominates it as a potential modulator of brain tumor vascular biology, including tumor angiogenesis and permeability.