Circ_0027599 elevates RUNX1 expression via sponging miR‐21‐5p on gastric cancer progression

Background Increasing evidence has shown that circular RNAs (circRNAs) serve as vital regulators in tumour progression. In this study, we focused on the functions of circ_0027599 in gastric cancer (GC) progression. Methods The levels of circ_0027599, runt-related transcription factor 1 (RUNX1) mRNA and microRNA-21-5p (miR-21-5p) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) assay. The protein levels of RUNX1, E-Cadherin, vimentin and N-Cadherin were measured by Western blot assay. Cell viability, colony formation, metastasis and cell cycle process were evaluated by Cell Counting Kit-8 (CCK-8) assay, colony formation assay, transwell assay and flow cytometry analysis, respectively. The interaction between circ_0027599 and miR-21-5p and the interaction between miR-21-5p and RUNX1 were verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The role of circ_0027599 in tumour growth in vivo was investigated by murine xenograft model assay. Results Circ_0027599 and RUNX1 were downregulated in GC tissues and cells. Circ_0027599 level was associated with the overall survival of GC patients. Circ_0027599 or RUNX1 overexpression inhibited GC cell viability, colony formation, migration, invasion and cell cycle process in vitro. For mechanism analysis, circ_0027599 positively regulated RUNX1 expression via functioning as the sponge for miR-21-5p. RUNX1 inhibition reversed circ_0027599 overexpression mediated malignant behaviours of GC cells. Moreover, circ_0027599 overexpression repressed tumour growth in vivo. Conclusion Circ_0027599 overexpression repressed GC progression via modulation of miR-21-5p/RUNX1 axis, which might illumine a novel therapeutic target for GC.