Resistin Promotes Nasopharyngeal Carcinoma Metastasis through TLR4-Mediated Activation of p38 MAPK/NF-κB Signaling Pathway

SIMPLE SUMMARY: Chronic inflammation is associated with the development of nasopharyngeal carcinoma (NPC). Mounting evidence has indicated that resistin is an inflammatory cytokine that is associated with the risk of tumorigenesis. However, the correlation between serum resistin levels and the risk of NPC remains unclear. Here, we found that high serum resistin levels in NPC patients were positively correlated with lymph node metastasis and that resistin promoted the metastasis of NPC cells both in vitro and in vivo. Furthermore, we elucidated the underlying molecular mechanisms through which resistin promotes metastasis in NPC cells by inducing the epithelial-mesenchymal transition (EMT). ABSTRACT: NPC is a type of malignant tumor with a high risk of local invasion and early distant metastasis. Resistin is an inflammatory cytokine that is predominantly produced from the immunocytes in humans. Accumulating evidence has suggested a clinical association of circulating resistin with the risk of tumorigenesis and a relationship between blood resistin levels and the risk of cancer metastasis. In this study, we explored the blood levels and the role of resistin in NPC. High resistin levels in NPC patients were positively associated with lymph node metastasis, and resistin promoted the migration and invasion of NPC cells in vitro. These findings were also replicated in a mouse model of NPC tumor metastasis. We identified TLR4 as a functional receptor in mediating the pro-migratory effects of resistin in NPC cells. Furthermore, p38 MAPK and NF-κB were intracellular effectors that mediated resistin-induced EMT. Taken together, our results suggest that resistin promotes NPC metastasis by activating the TLR4/p38 MAPK/NF-κB signaling pathways.