Inflammation-induced myeloid-derived suppressor cells associated with squamous cell carcinoma of the head and neck

Background. The purpose of this study was to present our assessment of the significance of myeloid-derived suppressor cells (MDSCs) in head and neck squamous cell carcinoma (HNSCC). Methods. We examined the percentage of MDSCs in the peripheral blood of patients with HNSCC. The relationship among MDSC recruitment, tumor progression, and cyclooxygenase (COX)-2 inhibition was also evaluated by animal models. Results. Circulating MDSCs were significantly increased in patients with HNSCC compared with healthy people, and this was associated with the clinical tumor burden. In immunocompetent 4-nitroquinoline-1-oxide (4-NQO)-induced oral tumor and immunocompromised tumor implantation animal models, MDSC recruitment was associated with the duration of 4-NQO treatment and tumor progression. The responsible mechanisms included the suppressive ability of T-cell proliferation and augmenting angiogenesis by MDSC. Blockade of COX-2 attenuated the induction and function of MDSCs and subsequently inhibited tumor growth. Conclusion. The levels of MDSC are linked with tumor progression in HNSCC. Moreover, targeting COX-2 could be a promising strategy for the treatment of HNSCC. (C) 2016 Wiley Periodicals, Inc.