Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that has been reported to enhance the aggressiveness and metastatic potential of tumor cells. However, the mechanisms through which MIF influences tumor development and progression are not understood. The objectives of our study were to assess the effects of tumor-derived MIF on neutrophils in head and neck cancer (HNC) and to identify possible feedback effects on tumor cells. To this end, we used an in vitro system to model the interaction between human HNC cells and neutrophils. In addition, we analyzed expression of MIF in tissues from HNC patients in relation to neutrophilic infiltration and clinical parameters. Our results show that human HNC is infiltrated by neutrophils proportional to the levels of tumoral MIF. Strong MIF expression by the tumor is associated with higher lymph node metastasis and reduced survival in HNC patients. In vitro, MIF modulated functions of human neutrophils by inducing chemokine CXC motif receptor 2(CXCR2)-dependent chemotaxis, enhancing neutrophil survival and promoting release of chemokine C-C Motif Ligand 4 (CCL4) and matrix metalloprotease 9(MMP9). Further, neutrophils activated with tumor-derived MIF enhanced migratory properties of HNC cells. In conclusion, our data indicate that the effects of tumor-derived MIF on neutrophils represent an additional mechanism by which MIF might contribute to tumor progression.
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