Profiling and functional analysis of exosomal circRNAs from EBV-associated gastric carcinoma CSCs

BACKGROUND: Recent studies have found that Epstein-Barr virus (EBV) encodes circular RNAs (ebv-circRNAs) that are involved in tumorigenesis process in EBV-associated gastric carcinoma (EBVaGC). Since little is known whether circRNAs can be enriched into exosomes and their functions in EBVaGC cancer stem cells (CSCs). METHODS: Exosomes from EBVaGC CSCs were isolated according to differential ultracentrifugation method. Expression patterns of ebv-circRNAs and human circRNAs in exosomes of EBVaGC CSCs were analyzed by RNA sequencing. CCK-8 assay, wound healing assay, transwell assay and apoptosis analysis were performed to explore the function of exosomes in EBVaGC CSCs. Data differences between two groups were evaluated using Student's t-test and survival analysis was performed by Kaplan–Meier methodology. RESULTS: Two circRNAs, ebv-circLMP2A and hsa-circRNF13 were enriched in EBVaGC CSCs derived exosomes, and positively associated with EBVaGC patients with metastasis. Bioinformatics analysis predicted that miR-5683 is the most likely potential target for both ebv-circLMP2A and hsa-circRNF13, and lower miR-5683 expression was positively correlated with microvessel density and Ki67 expression in clinical samples of EBVaGC. Cytology experiments preliminarily showed that EBVaGC CSCs derived exosomes significantly promoted the invasive growth of EBVaGC cells. CONCLUSIONS: Our findings suggest that exosomal circRNAs could be apromising diagnostic and therapeutic target for EBVaGC.