Tumor-infiltrating myeloid cells are involved in crucial processes during tumor development. A subset of monocytes that express the angiopoietin receptor Tie2 play an important role in tumor angiogenesis. Selective depletion of these Tie2-expressing monocytes (TEMs) in tumor-bearing mice inhibits tumor angiogenesis and growth, suggesting that they might regulate angiogenic processes in tumors by providing paracrine support to nascent blood vessels. TEMs have also been identified in human blood and tumors. We discuss here the therapeutic opportunities emanating from the discovery of TEMs, which include the identification of new antitumor targets, monitoring TEMs as surrogate markers for clinical responses in cancer patients, and the possible use of TEMs as cellular vehicles for gene delivery to tumors.
Douglas Hanahan, Nadine Fournier, Krisztian Homicsko, Mélanie Louise Tichet, Agnieszka Alicja Chryplewicz, Jeremy Gilles Louis Guillot, Simge Yücel, Mohammad Sadegh Saghafinia, Inti Zlobec, Yuqing Xie, Dalya Ataca, Qiqun Zeng, Fleuriane Marie Tryskele Laurene Gallean, Peng Zhang, Lucine Christe