Myeloid cells in cancer-related inflammation

Myeloid cells are key elements of the cancer-related inflammation with the potential to support not only tumor growth but also invasion and metastasis. Tumor-derived factors affect myeloid cell differentiation inducing a phenotype that supports tumor growth, inducing immunosuppression, angiogenesis and tissue remodeling. Soluble mediators, produced at primary tumor site, can also act in a remote mode inducing the release from bone marrow of myeloid cells that have immunosuppressive activities in tumor-draining lymphoid organs and can predispose to colonization when migrate to metastatic organs. We will here review current knowledge on the contribution of tumor-derived signals that affect polarized activation of myeloid cells, their bone marrow release and recruitment to metastatic sites with a particular focus on the role of chemokines.