Circ-CCDC66 accelerates proliferation and invasion of gastric cancer via binding to miRNA-1238-3p.

OBJECTIVE: The aim of this study was to examine the expression of circ-CCDC66 in gastric cancer (GC) tissues and cell lines, as well as its correlation with the prognosis of GC. Moreover, the regulatory effects of circ-CCDC66 on biological behaviors of GC cells and its molecular mechanism were explored. PATIENTS AND METHODS: The relative expression level of circ-CCDC66 in GC tissues and cell lines was determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between the circ-CCDC66 level and overall survival of GC patients was analyzed as well. The potential influences of circ-CCDC66 on proliferative and invasive abilities of GC cells were evaluated through 5-Ethynyl-2'-deoxyuridine (EdU), colony formation and transwell assay, respectively. Meanwhile, the cell cycle progression and apoptosis of GC cells affected by circ-CCDC66 were determined. In addition, the direct target miRNA of circ-CCDC66 was predicted and verified by bioinformatics method and Dual-Luciferase reporter gene assay, respectively. RESULTS: Circ-CCDC66 was significantly up-regulated in GC tissues and cell lines. Up-regulation of circ-CCDC66 indicated markedly worse prognosis of GC patients. Transfection of circ-CCDC66-siRNA remarkably attenuated proliferative and invasive abilities of BGC-823 and MGC-803 cells. Besides, GC cells were arrested in the G0/G1 phase, and the apoptotic rate was remarkably elevated after circ-CCDC66 knockdown. The Dual-Luciferase reporter gene assay verified that circ-CCDC66 bind to miRNA-1238-3p by competing with LHX2 (LIM-homeobox domain 2). MiRNA-1238-3p was significantly down-regulated in GC cells, whereas LHX2 was up-regulated. Furthermore, overexpression of miRNA-1238-3p in GC cells markedly suppressed the LHX2 level. CONCLUSIONS: Circ-CCDC66 is highly expressed in GC tissues and cell lines. Knockdown of circ-CCDC66 attenuates proliferative and invasive abilities of GC cells. Our results indicate that circ-CCDC66/miRNA-1238-3p/LHX2 axis may be a promising target for GC treatment.