Identification of a stable molecular signature in breast tumor endothelial cells that persists ex vivo. Mus musculus

Long-term, in vitro propagation of tumor-specific endothelial cells (TEC) allows for ex vivo functional studies and gene expression profiling of clonally-derived, well-characterized subpopulations. Using a genetically-engineered mouse model (GEMM) of mammary adenocarcinoma (C3-TAg), we have optimized an isolation procedure and defined growth conditions for long-term propagation of breast TEC. Based on expression of EC-selective markers, the isolated TEC maintain their endothelial specification and phenotype in culture. Furthermore, gene expression profiling of multiple TEC subpopulations revealed striking, persistent overexpression of several candidate genes including Irx2 and Zfp503 (transcription factors), Cd166 and Cd133 (cell-surface markers), Ccl12 and neurotensin (angiocrine factors), and Gpr182 and Cnr2 (G protein-coupled receptors). Taken together, we have described an effective method for isolating and culture-expanding breast TEC from a GEMM and we have uncovered several new TEC-selective genes whose overexpression persists even after long-term in vitro culture. These results suggest that stable changes may be induced in vascular endothelial cells in the tumor microenvironment in vivo that are transmittable ex vivo. Overall design: reference x sample