Fig. 1.

Matricellular protein regulation of tumor-associated myelopoiesis. Within the TME matricellular proteins have been shown to regulate myeloid cell behavior and functions at different levels. Tumor-produced SPARC and OPN promote MDSC expansion in BM and spleen via production of VEGF, IL-6, and GM-CSF [10, 49]. Tumor-derived SPARC promotes the recruitment of MDSCs at the tumor site via COX-2 and CXCR-4/CXCL12 axes, where they promote EMT and metastases [10]. OPN sustains the recruitment of MDSCs at the lung metastatic site where they are instrumental for the instruction of the metastatic niche. In addition, periostin takes part in creating the premetastatic niche [47]. Conversely, Gr-1-derived TSP-1 has been shown to counteract metastases development