Hsa_circ_0008667 promotes progression and improves the prognosis of gastric cancer by inhibiting miR-9-5p

Background and study aim: Gastric cancer (GC) is one of the most common gastrointestinal tumors characterized by aggressive development and poor prognosis. Circular RNAs (circRNAs) have been used as prognostic biomarkers and therapeutic targets in many cancers, including GC. Hsa_circ_0008667 is differentially expressed in GC; however, its function and clinical significance remained unelucidated. Therefore, this study aimed to investigate the role and significance of hsa_circ_0008667 in GC and its potential as a biomarker and therapeutic target of GC. Patients and methods: Through quantitative reverse-transcription real-time PCR, hsa_circ_0008667 expression in GC tissues and cells were analyzed, followed by statistical analyses to assess the clinical significance. Cell Counting Kit-8 and Transwell assays were performed to examine the effects of hsa_circ_0008667 silencing on GC cell growth and metastasis. Additionally, correlation analysis was performed to assess the relationship between hsa_circ_0008667 and miR-9-5p, which was further validated through luciferase reporter assay. Results: Hsa_circ_0008667 was considerably upregulated and tightly correlated with lymph node metastasis and the tumor-node-metastasis stage, which was predictive of poor prognosis in patients with GC. Hsa_circ_0008667 silencing suppressed GC cell proliferation, migration, and invasion. Furthermore, hsa_circ_0008667 negatively regulated miR-9-5p expression. MiR-9-5p downregulation enhanced GC malignancy and reversed hsa_circ_0008667 knockdown-mediated GC suppression. Conclusion: The findings of this study suggest hsa_circ_0008667 to be a prognostic biomarker and tumor promoter of GC via miR-9-5p modulation.