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Nasopharyngeal carcinoma (NPC) is the most common cancer with high metastatic potential that occurs in the epithelial cells of the nasopharynx. Distant metastases are the primary cause for treatment failure and mortality of NPC patients. However, the underlying mechanism responsible for the initiation of tumour cell dissemination and tumour metastasis in NPC is not well understood. Here, we demonstrated that epidermal growth factor receptor (EGFR) was highly expressed in tumour tissues of NPC patients with distant metastases and was associated with a decrease in reactive oxygen species (ROS). We also revealed that extracellular vesicles (EVs) transfer occurred from highly to poorly metastatic NPC cells, mediating cell–cell communication and enhancing the metastatic potential of poorly metastatic NPC cells. Further experiments indicated that EVs derived from highly metastatic NPC cells induced the up‐regulation of EGFR and down‐regulation of ROS in low metastatic NPC cells. Mechanistically, EGFR‐rich EVs‐mediated EGFR overexpression down‐regulated intracellular ROS levels through the PI3K/AKT pathway, thus promoting the metastatic potential of poorly metastatic NPC cells. Strikingly, treatment with EVs secreted from highly metastatic NPC cells was significantly associated with rapid NPC progression and shorter survival in xenografted mice. These findings not only improve our understanding of EVs‐mediated NPC metastatic mechanism but also have important implications for the detection and treatment of NPC patients accompanied by aberrant EGFR‐rich EVs transmission.

MicroRNAs have been verified as critical regulators in the development of melanoma. MiR-33a-5p was significantly downregulated in melanoma. However, the specific role and regulatory mechanism of miR-33a-5p in melanoma were still unclear. The present study identified that miR-33a-5p was downregulated in melanoma tissues and cells, while SNAI2 was upregulated. MiR-33a-5p directly targeted SNAI2 and negatively regulated its expression in melanoma cells. Overexpression of miR-33a-5p repressed proliferation, migration, invasion, EMT and promoted apoptosis of melanoma cell in vitro, these effects were partially reversed by SNAI2 overexpression. In addition, miR-33a-5p impaired melanoma growth in vivo by inhibiting SNAI2. Mechanistically, miR-33a-5p repressed activation of the PI3K/AKT/mTOR pathway by targeting SNAI2. In conclusion, miR-33a-5p repressed the progression of melanoma by targeting SNAI2 via inactivation of the PI3K/AKT/mTOR signaling pathway, providing a potential molecular mechanism for the treatment of melanoma.

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