Abstract
PURPOSE: The present in vivo/in vitro study was undertaken in order to evaluate the importance of macrophage migration inhibitory factor (MIF) in the progression of head and neck squamous cell carcinoma (HNSCC). METHODS: Tumor tissue expression (MIF immunostaining) and plasma levels (ELISA) of MIF were determined in HNSCC patients and correlated with tumor recurrence and metastasis, and overall survival. Furthermore, the impact of MIF expression on cell proliferation and anticancer drug sensitivity was examined in murine squamous carcinoma cell line SCCVII after MIF knockdown (MIF-KD). RESULTS: As revealed by quantitative analysis of MIF immunostaining, tumor progression was accompanied by an increase in mean optical density (MOD) and labeling index (LI). Likewise, an elevation of MIF serum levels was noted in HNSCC patients (n = 66) versus healthy individuals (n = 16). Interestingly, comparison of laryngeal carcinoma patients on the basis of MIF tissue expression (high expression, LI ≥ 47, versus low expression, LI < 47) disclosed a significant difference between disease-free survival curves for local and nodal recurrence, and overall survival curve. In vitro, MIF knockdown in murine SCCVII cells resulted in reduced cell proliferation and a decrease in cell motility. In mice inoculated with SCCVII cells, MIF-KD tumors grew more slowly and also appeared more sensitive to chemotherapy. CONCLUSIONS: Both clinical observations and experimental data suggest that MIF plays a pivotal role in the progression of HNSCC.