Circ-sirt1 inhibits growth and invasion of gastric cancer by sponging and upregulating

circRNAs have been considered as a rising factor in cancers. However, the roles and mechanisms of circ-sirt1 in gastric cancer (GC) remain largely unknown. In this study, we found that the expressions of sirt1 and circ-sirt1 are decreased in tissues or serums of GC patients by real-time 24 quantitative PCR (RT-qPCR). The expressions of miR-132-3p/miR-212-3p showed an opposite 25 tendency in these samples. The co-transfection of miR-132-3p/miR-212-3p mimics counteracted the 26 enhancement of sirt1 expression induced by circ-sirt1. The results of cell colony-formation assay and Transwell assays demonstrated that the proliferation, migration, and invasion activities of 28 BGC-823 cells were inhibited by circ-sirt1 overexpression or miR-132-3p/miR-212-3p knockdown, 29 respectively. The xenograft tumor model result indicated that the circ-sirt1 overexpression 30 suppressed the tumor growth of BGC-823 cells. The regulation of miR-132-3p/miR-212-3p 31 between circ-sirt1 and sirt1 was verified in the mice tumor tissues. Thus, circ-sirt1 inhibited tumor 32 growth and invasion probably by sponging miR-132-3p/miR-212-3p and upregulating sirt1 33 expression in GC. These findings may provide a theoretical basis for the classification of GC and a novel therapeutic target for GC patients. those the tissues and healthy subjects, respectively. These results demonstrated that sirt1 and circ-sirt1 are both lower expressed in GC tissues than in the noncancerous tissues, and the level of circ-sirt1 in serums from GC patients is lower than that noted from the healthy subjects. The data suggested that The data confirmed the anti-tumor function of circ-sirt1 and its downstream mechanism of miR-132-3p, miR-212-3p and sirt1 in mice model. The present work demonstrates that circ-sirt1 and sirt1 levels were decreased in tissues and serums of patients with GC, while miR-132-3p/miR-212-3p expressions show an opposite tendency in the GC patients. The miR-132-3p and miR-212-3p were downregulated in GC cells with circ-sirt1 overexpression, while sirt1 was upregulated at both mRNA and protein levels. The co-transfection of miR-132-3p/miR-212-3p mimics counteracted the enhanced expression of sirt1 induced by circ-sirt1 overexpression in BGC-823 cells. The circ-sirt1 was identified as a candidate from the sirt1 host gene in the human genome in our previous study, which expression is decreased during neointimal formation and acts as a novel biomarker of atherosclerosis. The circ-sirt1 could promote sirt1 expression mediating by miR-132/212. The present study found that circ-sirt1 acted as a suppressor in proliferation, migration and invasion in GC cells by sponging miR-132-3p/miR-212-3p to regulate the expression of sirt1. These suggested a similar function of circ-sirt1 in vascular smooth muscle cells and Glandular epithelial cells of stomach. However, if there is a positive feedback loop between circ-sirt1 and sirt1 in GC, as well as the expression and role of circ-sirt1 in other cancers, still need to be clarified in future study. to the enhancement of miR-132-3p/miR-212-3p induced by circ-sirt1. Overexpression circ-sirt1 suppressed the cell proliferation, migration and invasion in vitro and inhibited tumor growth in vivo . Our findings provide new sights into a novel molecular and the signaling of circ-sirt1/miR-132-3p/miR-212-3p/ sirt1 in GC development. in 293T cells was verified by RT-qPCR. C) The circ-sirt1 expressions in GES-1, AGS-1 and BGC-823 cells were analyzed by RT-qPCR, with GAPDH as internal control. D) The levels of circ-sirt1 in BGC-823 cells transfected with circ-sirt1 plasmid or vector were detected by RT-qPCR. GAPDH was used as the housekeeping gene. E) The protein levels of sirt1 were detected by Western blot with GAPDH as internal control. F) Clone formation, G) cell migration and invasion assays of BGC-823 cells transfected with pcDNA3/circ-sirt1 plasmid or pcDNA3.1 after 48 h. Results are representative of three independent experiments.