Exosomal circSTRBP from cancer cells facilitates gastric cancer progression via regulating miR-1294/miR-593-3p/E2F2 axis

CircRNAs represent a new class of non-coding RNAs which show aberrant expression in diverse cancers, such as gastric cancer (GC). circSTRBP, for instance, is suggested to be overexpressed in GC cells and tissues. However, the biological role of circSTRBP in the progression of GC and the potential mechanisms have not been investigated. circSTRBP levels within GC cells and tissues were measured by RT-qPCR. The stability of circSTRBP was assessed by actinomycin D and Ribonuclease R treatment. Cell proliferation, migration, invasion and in vitro angiogenic abilities after circSTRBP knockdown were analysed through CCK-8 assay, transwell culture system and the tube formation assay. The interaction of circSTRBP with the predicted target microRNA (miRNA) was examined by RNA immunoprecipitation and luciferase reporter assays. Xenograft tumour model was established to evaluate the role of exosomal circSTRBP in the tumour formation of GC cells. circSTRBP was upregulated in GC cells and tissues, and there was an increased level of circSTRBP in GC-derived exosomes. circSTRBP in the exosomes enhanced GC cell growth and migration in vitro, which modulates E2F Transcription Factor 2 (E2F2) expression through targeting miR-1294 and miR-593-3p. Additionally, exosomal circSTRBP promoted the tumour growth of GC cells in the xenograft model. Exosomal circSTRBP is implicated in the progression of GC by modulating the activity of miR-1294/miR-593-3p/E2F2 axis.