CircTNPO1 promotes the tumorigenesis of osteosarcoma by sequestering miR-578 to upregulate WNT5A expression

As a type of non-coding RNAs, circular RNAs (circRNAs) have the ability to bind to miRNAs and regulate gene expression. Recent studies have shown that circRNAs are involved in certain pathological events. However, the expression and functional role of circTNPO1 in osteosarcoma (OS) are not yet clear. To investigate circRNAs that are differentially expressed in OS tissues and cells, circRNA microarray analysis combined with qRT-PCR was performed. The in-vitro and in-vivo functions of circTNPO1 were studied by knocking it down or overexpressing it. The binding and regulatory relationships between circTNPO1, miR-578, and WNT5A were evaluated using dual luciferase assays, RNA pull-down and rescue assays, as well as RNA immunoprecipitation (RIP). Furthermore, functional experiments were conducted to uncover the regulatory effect of the circTNPO1/miR-578/WNT5A pathway on OS progression. Cytoplasm was identified as the primary location of circTNPO1, which exhibited higher expression in OS tissues and cells compared to the corresponding controls. The overexpression of circTNPO1 was found to enhance malignant phenotypes in vitro and increase oncogenicity in vivo. Moreover, circTNPO1 was observed to sequester miR-578 in OS cells, resulting in the upregulation of WNT5A and promoting carcinoma progression. These findings indicate that circTNPO1 can contribute to the progression of OS through the miR-578/WNT5A axis. Therefore, targeting the circTNPO1/miR-578/WNT5A axis could be a promising therapeutic strategy for OS.