Increased expression of macrophage migration inhibitory factor and DJ-1 contribute to cell invasion and metastasis of nasopharyngeal carcinoma

Background and aim: Both macrophage migration inhibitory factor (MIF) and DJ-1 protein have been shown to relate with cell invasion and metastasis in tumors. However, the role of DJ-1 in invasion and metastasis of nasopharyngeal carcinoma (NPC) and its relation to MIF expression in NPC are not fully understood. The aim of present study is to determine whether or not MIF and DJ-1 are correlated with tumor invasion and influence a worse outcome in NPC, as well as its related mechanism. Methods: 125 cases of NPC and 45 normal tissues of nasopharynx were collected. The expression of MIF and DJ-1 in tissue microarray was evaluated by immunohistochemical staining. Correlation between immunostainings and clinicopathological parameters, as well as the follow-up data of patients, was analyzed statistically. The association of MIF and DJ-1 with cell invasion and migration in NPC cell line were evaluated by small interfering RNA (siRNA) transfection, invasion assay and Western blotting. Results: MIF and DJ-1 staining was diffused and strong in tumor cells, whereas they were generally weaker and less common in normal lining epithelia of nasopharynx. High MIF expression in tumor cells (71.2%, 89/125 cases) were significantly associated with advanced clinical stage, lymph node metastasis, and worse prognosis of NPC patients. High expression of DJ-1 (75.2%, 94/125 cases) were closely correlated to lymph node metastasis and MIF high-expression. Only MIF high expression (P = 0.010) and lymph node metastasis (P = 0.004) emerged as strong independent prognostic factors for overall survival of NPC patients. In vitro, down-regulated expression of DJ-1 in NPC cell lines by siRNA was observed to reduce cell migration and invasion potential, however, exogenous MIF promoted cells invasion. Conclusions: The data provided evidence that increased expression of MIF and DJ-1 induced cell invasion and metastasis of NPC, supporting the idea that MIF and DJ-1 may play important roles as regulators in the progression of NPC.