Upregulation of circular RNA circ_0001721 predicts unfavorable prognosis in osteosarcoma and facilitates cell progression via sponging miR-569 and miR-599

Osteosarcoma (OS) is the most frequent bone malignancy in human. Growing evidence suggests that circular RNAs (circRNAs) play a significant role in regulating tumorigenesis and progression. Previously, circ_0001721 was identified upregulated in OS tissues screened by circRNA microarrays. In the current study, circ_0001721 expression in OS tissue samples and cells were measured by qRT-PCR. Its clinical value was also explored. For the part of functional assays, CCK-8, clone-forming, flow cytometric, Transwell, xenograft assays were performed. Dual luciferase reporter assays were used to examine the mechanism of circ_0001721. We found that circ_0001721 was enhanced in OS tissue samples and cell lines and the overexpression of circ_0001721 is closely related to clinical severity. In addition, circ_0001721 may be used as a prognostic indicator for OS patients. What's more, loss-of-function and gain-of-function assays demonstrated circ_0001721 facilitates cell progression in OS. Circ_0001721 could sponge miR-569 and miR-599. The oncogenic properties of circ_0001721 is partly attributed to its repression on miR-569 and miR-599. Collectively, the present data reveal the participation of circ_0001721 in tumorigenesis of OS cells, and may indicate a novel therapeutic target.