鼻咽癌远处转移是治疗失败的主要原因，肿瘤来源的外泌体在肿瘤的发生发展中扮演重要角色。我们前期通过共培养发现鼻咽癌高转移细胞来源的外泌体促进低转移细胞的迁移和侵袭及细胞的上皮-间充质转化；进一步分析高低转移细胞外泌体的circRNAs表达谱，发现circ_REEP5在高转移细胞外泌体中的表达明显上调，在临床鼻咽癌标本里表达明显高于正常鼻咽上皮；过表达circ_REEP5促进鼻咽癌细胞的转移。我们因此提出科学假说：鼻咽癌高转移细胞来源的外泌体促进低转移细胞的迁移和侵袭能力，外泌体中circ_REEP5表达显著上调，外泌体circ_REEP5通过竞争性结合miR-410-3p上调Serglycin的表达来实现促进鼻咽癌迁移和侵袭的作用。本项目将进一步明确circ_REEP5促进鼻咽癌转移的机制、阐明circ_REEP5在肿瘤的高表达与鼻咽癌患者的预后关系，为鼻咽癌寻找新靶点提供依据。

Distant metastasis is the main reason for treatment failure of Nasopharyngeal carcinoma (NPC).Tumor-derived exosomes play an important role in tumorigenesis and metastasis.Our preliminary experiments showed that the exosome from high-metastasis NPC cells could improve the migratory and invasive abilities, as well as the epithelial-mesenchymal translation of low-metastasis NPC cells. By analyzing whole small RNA expression profiling data comparing the exosome from low- versus high-metastasis NPC cells, we found that exosomal circ_REEP5 expression was dramatically upregulated in high-metastasis cells. The upregulated expression of circ_REEP5 in the primary NPC tested by qRT-PCR were also proved. By overexpression circ_REEP5 in cells, we further studied the effect of circ_REEP5 on the metastasis in vitro. We therefore propose a hypothesis: exosomes derived from high metastatic cells of NPC promote the migration and invasion of low metastatic cells; exosomal circ_REEP5 improves NPC metastasis through competitive binding miR-410-3p and up-regulating Serglycin expression. In the proposed study, we will use a series of in vitro and in vivo approaches to explore the mechanism of exosomal circ_REEP5 in metastasis and clarify the relationship between exosomal circ_REEP5 and NPC prognosis. The accomplishment of the proposed study will help to find a new target for metastasis prevention and treatment.