Circ_0049447 acts as a tumor suppressor in gastric cancer through reducing proliferation, migration, invasion, and epithelial-mesenchymal transition

Background:Although increasing abnormal expression of circular RNAs(circRNAs)has been revealed in various cancers,there were a small number of studies about circRNAs in gastric cancer(GC).Here,we explored the expression and function of a novel circRNA,circ_0049447,in GC.Methods:A total of 80 GC tissues and non-tumorous tissues were collected from the First Affiliated Hospital of China Medical University.And all cells were cultured with 10%fetal bovine serum and incubated at 37°C and 5%CO2.The expression of circ_0049447 was quantified by real-time polymerase chain reaction.The biological function of circ_0049447 on proliferation,migration,invasion,and epithelial-mesenchymal transition(EMT)was evaluated by cell counting kit-8(CCK-8),colony formation assay,transwell migration and invasion assay,and Western blotting.Luciferase report assay was used to verify the direct binding between circ_0049447 and predicted microRNA(miRNA).Furthermore,a xenograft mouse model was used to validate the function of circ_0049447 in vivo.Results:We demonstrated that circ_0049447 was downregulated in GC(P<0.001).The area under the receiver operating characteristic curve reached 0.838,while sensitivity was 82.3%and specificity was 77.2%.CCK-8 and colony formation assay showed that overexpression of circ_0049447 could inhibit the proliferation(P<0.05).Transwell migration and invasion assay showed upregulated circ_0049447 could impede migration in GC cells(P<0.05).In addition,overexpression of circ_0049447 could impede GC cell EMT.Upregulation of miR-324-5p in GC specimens and direct binding between miR-324-5p with circ_0049447 proven by luciferase reporter assay indicated that circ_0049447 may inhibit GC by sponging certain miRNA.Conclusion:Circ_0049447 acts as a tumor suppressor in GC through reducing proliferation,migration,invasion,and EMT,and it is a promising biomarker for diagnosis.