The role of myeloid derived suppressor cells in cancer

Abstract

Inflammation is established as one of the central hallmarks of cancer. Although the immune system plays an indispensable role in immunosurveillance against cellular transformation, ample evidence demonstrates that certain immune cells can be unwitting conspirators in the promotion of tumors. Immature myeloid cells frequently accumulate in the tumor microenvironment and peripheral organs of cancer patients and in mouse tumor models and correlate with tumor progression and poor survival. Myeloid-derived suppressor cells are a heterogeneous population of immature myeloid cells with profound immunosuppressive abilities that contribute to immune dysfunction and tumor progression. In this chapter, the phenotypic and functional characteristics of MDSC, and the mechanisms underlying their development, accumulation and suppressor functions in murine and human cancers are described. The molecular and immunotherapeutic targeting of those pathways contributing to MDSC expansion and/or function are highlighted for their potential to overcome MDSC-mediated immunosuppression in tumor-bearing hosts and improve cancer treatment strategies.