Development of circRNAs expression signatures in exosomes derived from different gastric cancer cells

Exosomes from the culture media (CM) of four GC cells (GCCs) and human gastric epithelial cells were isolated. Exosomal RNA was extracted, and circRNA microarray assay was performed to identify GC-specific exosomal circRNAs. A total of 58 exosomal circRNAs were expressed at considerable higher levels in GCCs than those in normal controls.The expression level of several top upregulated circRNAs were detected using qRT-PCR in both GC cells and clinical specimens of GC patients. More interesting, besides the high expression in GC cell derived exosomes, hsa_circ_0015286 was the uniquely upregulated circRNA in the plasma exosomes and tissues of GC patients..The result suggested that exosomal hsa_circ_0015286 may be a potential noninvasive biomarker for the diagnosis and prognosis monitoring of GC. Four human GCC lines (MGC803, BGC823, SGC7901, and AGS) and one normal human gastric (GES-1) cell line were cultured at 37 °C with 5% CO2 in 1640/DMEM containing 10% exosome-depleted FBS. Exosomal RNA from the CM of four GCCs and GES-1 were purified, five independent samples were collected and circRNA microarray assay was conducted to identify GC-specific exosomal circRNAs.