Suppression of circ_0008932 inhibits tumor growth and metastasis in osteosarcoma by targeting miR-145-5p

Osteosarcoma (OS) is a common type of primary malignant tumor. Although the pathogenesis of OS has been extensively studied, the underlying molecular mechanisms have remained to be fully elucidated. Accumulating evidence has revealed that dysregulation of various circular RNAs (circRNAs) is associated with tumorigenesis and recent studies have indicated that circRNA circ_0008932 is aberrantly expressed in tumors. In the present study, the expression and detailed function of circ_0008932 in OS were elucidated. The levels of circ_0008932 in OS samples and cell lines were examined using reverse transcription-quantitative PCR. A cell model with circ_0008932 knockdown was generated using specific small interfering RNA (si-circ_0008932). Cell viability was determined by a Cell Counting Kit-8 assay, the cell migratory/invasive capacity was evaluated using Transwell assays and cell apoptosis was assessed by flow cytometry. The results suggested that circ_0008932 was upregulated in most primary OS tumors, suggesting that circ_0008932 is associated with the development of OS. In the in vitro assays, si-circ_0008932 inhibited the proliferation, migration and invasion of OS cells, while apoptosis was promoted. A luciferase reporter assay revealed that circ_0008932 may downregulate microRNA (miR)-145-5p through direct binding. Furthermore, the expression of miR-145-5p was negatively correlated with circ_0008932 levels in OS specimens. In addition, further functional studies indicated that miR-145-5p inhibitors eliminated the effects caused by si-circ_0008932 in OS cells. In comparison, the changes in the biological behavior of OS cells transfected with si-circ_0008932 were enhanced by miR-145-5p. In summary, circ_0008932 may be a novel oncogenic factor during the progression and development of OS by targeting miR-145-5p; more importantly, circ_0008932 may be a potential therapeutic target for OS.