Recent findings indicate that tumor-associated macrophages are important drivers of tumor angiogenesis. Here, we review the essential role played by Tie2-expressing monocytes (TEM) in this phenomenon. TEMs are present in human blood and tumors and their elimination in various tumor models suppresses tumor angiogenesis. A ligand for Tie2, angiopoietin-2 (Ang-2), is produced by angiogenic tumor vessels and is a chemoattractant for TEMs. Hypoxia up-regulates Tie2 expression on TEMs and, together with Ang-2, down-regulates their antitumor functions. Learning more about the regulation of TEMs by the tumor microenvironment may yield new strategies to ablate the tumor vasculature.
Freddy Radtke, Nadine Fournier, Etienne Meylan, Justine Pascual, Anita Bodac, Amber Dawn Bowler, Vincent Roh
Didier Trono, Priscilla Turelli, Sandra Eloise Kjeldsen, Cyril David Son-Tuyên Pulver, Evaristo Jose Planet Letschert, Filipe Amândio Brandão Sanches Vong Martins, Olga Marie Louise Rosspopoff, Joana Carlevaro Fita, Romain Forey, Florian Huber