Hypoxia-Induced Matrix Metalloproteinase-13 Expression in Exosomes from Nasopharyngeal Carcinoma Enhances Metastases

Exosomes are nano-vesicles secreted by tumor cells. Exosomes can transfer complex biological information and induce a diverse signaling response in a wide array of pathological conditions, such as hypoxia. Hypoxia is associated with aggressive phenotypes and poor outcomes in nasopharyngeal carcinoma (NPC) patients. Here, we analyzed the role of exosomes from hypoxic NPC cells in enhancing the metastases of normoxic cells in a hypoxia-induced factor-1α (HIF-1α)-dependent manner. HIF-1α rapidly accumulates and trans-activates hundreds of genes, such as matrix metalloproteinases (MMPs). We found that MMP-13 was over-expressed in exosomes and cells under hypoxic conditions. HIF-1α depletion in hypoxic CNE2 cells led to decreased MMP-13 levels in exosomes and significantly reduced cell migration and invasion. Moreover, exosomal MMP-13 significantly up-regulated Vimentin expression while decreasing E-cadherin levels in CNE2 cells in vitro and in vivo. Furthermore, MMP-13 levels were closely associated with HIF-1α expression (r = 0.679, P < 0.001), lymph node metastasis, clinical stage (all P < 0.05) and poor prognosis in NPC patients (P < 0.01). In conclusion, our findings suggest that the hypoxic exosomes were loaded with MMP-13, which could enhance migration and invasiveness and induce microenvironment changes to promote NPC aggressiveness.