Circular RNA circ_0000337 contributes to osteosarcoma via the miR-4458/BACH1 pathway

BACKGROUND: As the most prevalent primary bone malignancy in children and adolescents, osteosarcoma (OS) has attracted increasing attention. The role of circRNAs in OS has been elucidated in some reports, but many circRNAs remain unexplored. Circ_0000337 has only been revealed as an oncogenic circR NA in esophageal squamous cell carcinoma. Yet whether circ_0000337 exerts any specific function in OS has not been unmasked. METHODS: RT-qPCR was used for measurement of circ_0000337, miR-4458 and BACH1 mRNA levels. Western blot was conducted to detect BACH1 protein. CCK-8 assay, Casepase-3 activity assay and transwell assay were utilized to assess changes on cellular processes. Cytoplasmic/nuclear fractionation assay was conducted for circ_0000337 localization in OS cells. Luciferase reporter assay and RIP assay were performed to validate the interaction between miR-4458 and circ_0000337 or BACH1. RESULTS: Circ_0000337 expression was upregulated in OS cell lines and it silence hindered OS cell proliferation and migration. MiR-4458 was downregulated in OS cells and miR-4458 upregulation suppressed OS cell growth and migration. Importantly, circ_0000337 sponged miR-4458 to elevate BACH1 expression, thus facilitating OS development. CONCLUSIONS: This research for the first time documented that circ_0000337 promoted OS progression via sponging miR-4458 and thus elevating BACH1 expression, offering rational therapeutic target for OS.