Association of Chemokines and Chemokine Receptor Expression with Monocytic-Myeloid-Derived Suppressor Cells during Tumor Progression

Myeloid-derived suppressor cells (MDSCs) are highly immunosuppressive myeloid cells that show increased expression in cancer patients; however, the molecular mechanisms underlying their generation and function are unclear. Whereas granulocytic-MDSCs correlate with poor overall survival in breast cancer (BC), the presence and relevance of monocytic (Mo)-MDSCs are unknown. Here, we report for the first time increased chemokine and chemokine receptor production by Mo-MDSCs in BC patients. A clear population of Mo-MDSCs with the typical cell surface phenotype (human leukocyte antigen-antigen D related [HLA-DR](low/−) CD11b(+) CD33(+) CD14(+)) increased significantly during disease progression. In addition, the chemokine receptor expression level on Mo-MDSCs in patients with invasive BC was the highest. Furthermore, different chemokine receptor expression patterns were noted in Mo-MDSCs between healthy controls (HC) and BC patients. Additionally, CD4 T cells proliferations were significantly decreased in the invasive BC groups compared with the HC group. However, the ductal carcinoma in situ (DCIS) group had no significantly compared with the HC group. Our data suggest that monitoring chemokine and chemokine receptor production by Mo-MDSCs may represent a novel and simple biomarker for assessing disease progression in BC patients.