Circular RNA profiling in plasma exosomes from patients with gastric cancer.

Gastric cancer (GC) is among the most common cancer types worldwide with high mortality. Recent studies have shown that exosomes play a crucial role in the tumorigenesis of GC. The present study aimed to investigate the circular RNA (circRNA) profile in plasma exosomes from patients with gastric cancer (GC). Peripheral blood samples were collected from 5 patients with GC and 5 healthy donors, and exosomes were isolated from plasma. The high-throughput RNA sequencing (RNA-seq) method was applied to detect the differently expressed circRNAs (DE circRNAs). Subsequently, sequencing results were confirmed by reverse transcription quantitative (RT-q) PCR. The potential roles of DE circRNAs in GC were identified using Gene ontology (GO) and Kyoto Encyclopedia of Gene and Genome (KEGG) analysis. Furthermore, MiRanda software was used to predict circRNA-micro-RNA (miRNA) interactions. A total of 67,880 circRNAs were identified in all samples and 1,060 significantly DE circRNAs were screened, including 620 upregulated and 440 downregulated ones. These results were further confirmed by RT-qPCR. GO and KEGG analyses revealed that these circRNAs were significantly associated with 'cell cycle', 'cytoskeleton organization', 'cellular response to DNA damage', 'regulation of GTPase activity', 'phosphatidylinositol signaling pathway', 'MAPK signaling pathway', 'thyroid hormone signaling pathway', 'chemokine signaling pathway' and 'Wnt signaling pathway'. In addition, a circRNA-miRNA-mRNA interaction network was established. Taken together, these findings may help better understanding the underlying mechanisms of GC and identifying new molecular alterations in GC, and allow the enrichment of the circRNA profiling in human GC.