[Blood vessels in cancer: can't stop whispering]

Tumor initiation and progression is a complex process in which cells acquire aberrant proliferation, survival and migration properties, and the ability to form a dedicated blood vessel network. Recent studies highlighted the existence of an active crosstalk between endothelial cells and the tumor mass. Indeed, cancer stem-like cells have been identified and found in the vicinity of blood vessels, and the latter has been proposed to act as a feeding bed for tumors, especially governing the fate of cancer stem-like cells. Here, we present an overview of the direct interplay between endothelial and cancer cells. We will first introduce the mechanisms involved in tumor angiogenesis. How the microenvironment impacts on endothelial plasticity will next be detailed, focusing on the tumor main secreted factors. Finally, the role of the vascular niche and its angiocrine factors in tumorigenesis will be addressed.