Single cell analysis of tumor endothelial cells during vessel co-option

Cancer cells require a continuous supply of nutrients and oxygen to sustain growth and have adapted to promote angiogenesis by secreting soluble factors that induce vascularization (for example Vascular Endothelial Growth Factor - VEGF and basic Fibroblasts Growth Factor - bFGF) (Hanahan et al. Cell 144: 646, 2011). However, anti-angiogenic therapies suffer from clinical inefficacy either due to acquired resistance or to intrinsic refractoriness (Jayson et al. The Lancet 388: 518, 2016). One of the possible resistance mechanism that has been overlooked for years is "vessel co-option", a non-angiogenic process of tumor vascularization in which cancer cells hijack the pre-existing blood vessels of the organ they are invading, without forming new ones (Pezzella et al. Am J Pathol 151: 1417, 1997). In order to gain new insights into vessel co-option, I will perform single cell RNA-sequencing (scRNAseq) on isolated tumor endothelial cells (TECs) from two complementary models: -a glioblastoma mouse model in which, after cancer cell injection, brain tumors grow selectively either via sprouting angiogenesis (Olig2-/-, p53-/-, mutant Endothelial Growth Factor Receptor - EGFRvIII) or vessel co-option (Olig2+/-, p53-/-, mutant EGFRvIII) (Metha et al. Cancer Cell 19: 359, 2011);-a renal cancer lung metastasis mouse model, in which the metastases show a mixed pattern of angiogenesis and vessel co-option, as is often the case in human tumors. Using an advanced bioinformatics approach, I will first characterize the molecular profile of angiogenic versus vessel co-opted TECs and identify possible therapeutic targets for vessel co-option. Then, I will validate the expression of these targets via immunostainings on tissue sections, Fluorescence In Situ Hybridization (FISH) and digital Polymerase Chain Reaction (dPCR) assays. Moreover, I will perform inhibition tests with antisense nucleotides or pharmacological inhibitors, when available. Finally, if time permits, I will generate conditional knock-out mice in order to further confirm my findings in vivo.

Keywords:Angiogenesis, Vessel co-option, scRNAseq, Glioma tumor model, Tumor Endothelial Cells

Disciplines:Cardiac and vascular medicine

Project type:PhD project