Fig. 8. Proposed model of CD11b+Gr1+ cell activation within the bone marrow of prostate tumor hosts via PTHrP.
Prostate tumor-derived PTHrP circulates to stimulate VEGF-A and IL-6 expression by osteoblasts, leading to SFK phosphorylation of CD11b+Gr1+ MDSCs. Activation of SFK confers angiogenic potential of MDSCs via increased MMP-9 expression, contributing to prostate cancer growth and angiogenesis.