Abstract
The role of nitric oxide (NO)(·) in the development of the metastatic properties of nasopharyngeal carcinoma (NPC) is not fully understood. Previous studies proposed that interleukin-6 (IL-6) would act as regulator of matrix metalloprotease activation in NPC. Recently, we showed that (NO)(·) was a critical mediator of tumor growth in patients. The aim of this study was to determine the implication of IL-6 in the progression of NPC pathology via metalloprotease (MMP) activation and their possible correlation with (NO)(·) production. We observed a significant increase in IL-6 and nitrite (NO2 (-)) synthesis in patients (n = 17) as well as a strong expression of IL-6 and nitric oxide synthase 2 (NOS2) in the analyzed tumors (n = 8). In patients' plasma, a negative correlation associated IL-6 with circulating nitrites (r = -0.33). A negative correlation associated the H-scores of these signals in the tumors (r = -0.47). In patients' plasma, nitrite synthesis was positively associated with MMP-9 activation (r = 0.45), pro-MMP-2 expression (r = 0.37), and negatively correlated with MMP-2 activation (r = -0.51). High nitrite levels was associated with better recurrence-free survival (RFS) (p = 0.02). Overall, our results suggest that the IL-6/NOS2 inflammatory signals are involved in the regulation of MMP-9- and MMP-2-dependent metastatic activity and that high circulating nitrite levels in NPC patients may constitute a prognostic predictor for survival.