MMP-9 expression in peripheral blood mononuclear cells and the association with clinicopathological features and prognosis of nasopharyngeal carcinoma

BACKGROUND: Matrix metalloproteinase-9 (MMP-9) shows significant involvement with cancer invasion and therefore has prognostic significance. Tumor tissues from nasopharyngeal carcinoma (NPC) patients are not easy to access, and peripheral blood mononuclear cells (PBMC) are a valuable alternative. This study compared the expression levels of MMP-9 in PBMCs from NPC patients and healthy controls and evaluated the potential as a prognostic biomarker for NPC patients. METHODS: MMP-9 mRNA concentrations in PBMCs from 146 NPC patients and 110 healthy controls were measured using quantitative real-time PCR. Differences in MMP-9 expression between NPC patients and controls were evaluated using non-parametric tests, and the effects of different clinical characteristics on MMP-9 expression were also analyzed. The Kaplan-Meier test and Cox regression model were used to explore the association between MMP-9 expression and overall survival of NPC patients. RESULTS: MMP-9 mRNA levels in PBMCs were significantly higher in NPC patients than in healthy controls (p<0.001). Increased MMP-9 expression was associated with the following clinical characteristics: advanced clinical stage (p<0.001), T stage (p=0.016), N stage (p=0.002), histology type (p=0.037), and poor overall survival (p=0.049). CONCLUSIONS: MMP-9 mRNA expression in PBMCs from NPC patients is increased and associated with the clinical characteristics and overall survival. It supports the belief that MMP-9 may contribute to the progression of NPC.