Stem Cells Come to Squamous Cell Carcinoma

Cancer stem cells (CSCs) attract a lot of attention, because they are considered to be a stable, long-lived, therapeutically resistant population of cells from which tumor cells originate. Using a well-established model of chemical carcinogenesis in mice, these authors localized CD34⁺ tumor epithelial cells (previously shown to be CSCs) to the vascular niche, within 40 µm of endoglin-expressing endothelial cells. Treating the mice with anti–vascular endothelial growth factor (VEGF) receptor 2 antibodies resulted in a decreased tumor burden and fewer vessels, as expected; conversely, forced VEGF overexpression by tumor cells resulted in larger tumors. The researchers identified neuropilin-1 (Nrp1) as the VEGF receptor most highly expressed o…