Myeloid-derived suppressor cells and their role in gynecological malignancies

Myeloid-derived suppressor cells are a heterogeneous population of immature myeloid cells that exhibit immunosuppressive activity (they block the proliferation and activity of both T cells and natural killer cells). In addition to their role in suppressing immune responses, myeloid-derived suppressor cells directly stimulate tumor cell proliferation, metastasis, and angiogenesis. In the area of gynecological cancer, increased numbers of circulating myeloid-derived suppressor cells or tumor-infiltrating myeloid-derived suppressor cells have been detected, and the increased frequencies of myeloid-derived suppressor cells are associated with a poor prognosis. Thus, the successful myeloid-derived suppressor cells depletion may hold the key to maximizing existing anti-cancer therapies and improving the prognosis of gynecological cancer. In this review, we summarize current knowledge regarding myeloid-derived suppressor cells biology, clinical significance of myeloid-derived suppressor cells, and the potential myeloid-derived suppressor cells-targeting strategies in gynecological cancer.