Macrophage migration inhibitory factor is a novel prognostic marker for human oral squamous cell carcinoma

Macrophage migration inhibitory factor (MIF) is considered a pro-tumour factor. However, its clinical relevance in oral squamous cell carcinoma (OSCC) remains unclear. The objective of this study was to investigate the expression of MIF and its receptor CD74 in OSCC tissues, and to study the function of MIF in OSCC cells. Tissues of 90 patients with OSCC from the School of Stomatology, China Medical University were collected, and immunohistochemical staining and quantitative reverse transcription polymerase chain reaction were performed for MIF and CD74. The possible correlations between MIF and CD74 and clinical characteristics were analysed. The Kaplan-Meier analysis was used to determine the survival rates of patients. In addition, the proliferation and invasion of OSCC cells were evaluated after transfection with siRNA against MIF. MIF and CD74 levels were significantly higher in tissues of patients with OSCC than in control tissues. Moreover, MIF levels in patients with OSCC were significantly associated with cell differentiation and TNM classification. MIF expression was closely related to CD74 expression. Kaplan-Meier analysis indicated that OSCC patients with high MIF levels showed reduced overall survival and recurrenc-free survival. Furthermore, MIF expression promoted proliferation and invasion of OSCC cells. Collectively, our results reveal that MIF expression is a significant independent prognostic factor for patients with OSCC and may be a novel prognostic marker for OSCC.