Hsa‐circ_0000064 accelerates the malignant progression of gastric cancer via sponging microRNA‐621

Abstract Gastric cancer (GC) is one of the most common digestive system tumors in the world. Many circular RNAs (circRNAs) are involved in the progression of GC. The purpose of this study was to delve into the expression characteristics and biological functions of circ_0000064 in GC, and further study its mechanisms. Quantitative real‐time polymerase chain reaction (qRT‐PCR) was performed to detect circ_0000064 expression in 61 GC tissues and cell lines. Circ_0000064 knockdown was successfully modeled with siRNA. The effects of circ_0000064 on the biological functions of GC cells were analyzed by CCK‐8, BrdU, and Transwell assays. Bioinformatics and dual‐luciferase reporter gene assay were adopted to explore the relations between circ_0000064 and microRNA‐621 (miR‐621). Western blot was used to examine the regulatory function of circ_0000064 and miR‐621 on SYF2 pre‐mRNA splicing factor 2. Cric_0000064 expression was elevated in GC tissues and cell lines. Knocking down cric_0000064 could inhibit the viability, migration, and invasion of GC cells. Dual‐luciferase reporter gene assay showed that miR‐621 could bind circ_0000064 and SYF2 3'UTR; in addition, miR‐621 overexpression or SYF2 knockdown could partially weaken the cancer‐promoting effect of circ_0000064 on GC cells. Circ_0000064 expression was negatively correlated with miR‐621 expression in GC tissues while positively with SYF2 expression. Circ_0000064 can participate in the GC progression via modulating miR‐621/SYF2 axis. This implies that circ_0000064 may be a new diagnosed biomarker or a new therapeutic target of GC.