Mutualistic effects of the myeloid-derived suppressor cells and cancer stem cells in the tumor microenvironment

Abstract

Myeloid-derived suppressor cells (MDSCs) are derived from myeloid progenitor cells present in the bone marrow. When the differentiation of the myeloid progenitor cells is impaired, MDSCs arise. The immunosuppressive functions of the MDSCs are significantly upregulated in the tumor microenvironment. MDSCs are promoted by many inflammatory molecules. Likewise, chemokines, cytokines, and enzymes that are secreted by MDSCs mediate tumor cell invasion, proliferation, survival, and adhesion. Cancer stem cells (CSCs) are known as malignant cancer cells with characteristics such as self-regeneration and differentiation. Cancer stem cells have been the focus of many cancer studies for many years. Recently, MDSCs have also become the focus of cancer researchers. According to a hypothesis, both CSCs and MDSCs have mutual effects on the development of cancer. Therefore, the aims of this review are to summarize the link between CSCs and MDSCs and to describe the immunosuppressor metastatic properties of the MDSCs. © 2019 Begell House, Inc.