Figure 1.

Abnormal pericyte coverage of tumor vessels affects tumor development. PDGF-β signaling controls pericyte recruitment during angiogenesis. Hyperactivation of this pathway within TME may increase pericyte coverage, thereby improving vasculature stability and perfusion, which favors tumor growth. In contrast, low pericyte coverage compromises vessel structure integrity, which becomes leaky, facilitating tumor cell invasion/extravasion. Under such circumstances, tumor cells may also undergo EMT induced by hypoxia, as a consequence of lower perfusion in the tumor vasculature. Both situations enhance metastatic spread of tumor cells.