Compelling evidence has indicated the vital role of lysine-specific demethylase 4 A (KDM4A), hypoxia-inducible factor-1α (HIF1α) and the mechanistic target of rapamycin (mTOR) signaling pathway in nasopharyngeal carcinoma (NPC). Therefore, we aimed to investigate whether KDM4A affects NPC progression by regulating the HIF1α/DDIT4/mTOR signaling pathway. First, NPC and adjacent tissue samples were collected, and KDM4A protein expression was examined by immunohistochemistry. Then, the interactions among KDM4A, HIF1α and DDIT4 were assessed. Gain- and loss-of-function approaches were used to alter KDM4A, HIF1α and DDIT4 expression in NPC cells. The mechanism of KDM4A in NPC was evaluated both in vivo and in vitro via RT-qPCR, Western blot analysis, MTT assay, Transwell assay, flow cytometry and tumor formation experiments. KDM4A, HIF1α, and DDIT4 were highly expressed in NPC tissues and cells. Mechanistically, KDM4A inhibited the enrichment of histone H3 lysine 9 trimethylation (H3K9me3) in the HIF1α promoter region and thus inhibited the methylation of HIF1α to promote HIF1α expression, thus upregulating DDIT4 and activating the mTOR signaling pathway. Overexpression of KDM4A, HIF1α, or DDIT4 or activation of the mTOR signaling pathway promoted SUNE1 cell proliferation, migration, and invasion but inhibited apoptosis. KDM4A silencing blocked the mTOR signaling pathway by inhibiting the HIF1α/DDIT4 axis to inhibit the growth of SUNE1 cells in vivo. Collectively, KDM4A silencing could inhibit NPC progression by blocking the activation of the HIF1α/DDIT4/mTOR signaling pathway by increasing H3K9me3, highlighting a promising therapeutic target for NPC.

Background: Extracellular vesicles (EVs) can be secreted by a wide variety of cells, including tumor cells, and contain some bioactive molecules from the source cells. Therefore, they can potentially be used as biomarkers for early diagnosis of tumors and for tumor therapy. In addition, EVs can affect the features of target cells and participate in regulating the development process of tumors. Methods:A literature review was conducted to elucidate the role of extracellular vesicles in the progression and treatment of nasopharyngeal carcinoma. Results:In this review, we discuss the molecular mechanisms of cell proliferation, angiogenesis, epithelial-mesenchymal transformation and metastasis, immune response, and chemo-radiotherapy resistance that are induced by EVs. We also reviewed the potential applications of EVs as biomarkers, therapeutic agents, and carriers so as to determine new directions for the early diagnosis and targeted therapy of nasopharyngeal carcinoma. The application limitations have also been discussed in this review, further work is needed to ensure optimal outcomes for patients. Conclusion:Although the roles of extracellular vesicles in the progression of nasopharyngeal carcinoma have been summarized, some aspects are still unclear and need to be further studied. In addition, the applications of extracellular vesicles in the treatment of nasopharyngeal carcinoma still need to optimize conditions to produce better therapeutic outcomes for patients with nasopharyngeal carcinoma.

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