Circular RNA F-circEA-2a expression is increased in gastric adenocarcinoma and inhibits the transition from premature microRNA-3940-5p to mature microRNA-3940-5p

Circular RNA (circRNA) F-circEA-2a and micorRNA (miR)-3940-5p are two non-coding RNAs with critical roles in cancer biology. However, their participation in gastric adenocarcinoma (GA) is unclear. We predicted that miR-3940-5p could bind to F-circEA-2a and speculated that miR-3940-5p may interact with F-circEA-2a to participate in cancer biology. This study was conducted to explore the interaction between F-circEA-2a and miR-3940-5p in GA. F-circEA-2a and miR-3940-5p (mature and premature) levels in GA were detected using RT-qPCR. Their correlations were analyzed by Pearson’s correlation coefficient. The role of F-circEA-2a in miR-3940-5p maturation was analyzed using overexpression assay. The direct binding of premature miR-3940-5p to F-circEA-2a was analyzed by RNA-RNA pulldown. Proliferation was analyzed with BrdU assay. We found that F-circEA-2a and premature miR-3940-5p were overexpressed in GA, while mature miR-3940-5p was under-expressed in GA. F-circEA-2a suppressed miR-3940-5p maturation in GA cells. MiR-3940-5p directly bound to F-circEA-2a wild type (-wt), but not mutant (-mut). F-circEA-2a promoted GA cell proliferation and inhibited the role of miR-3940-5p in reducing cell proliferation. Therefore, F-circEA-2a might suppress mature miR-3940-5p formation by sponging premature miR-3940-5p to promote cell proliferation in GA. Our study characterized a novel circRNA regulating miR-3940-5p maturation in GA.