Abstract Osteosarcoma (OS) is a common malignant tumor in the world. Circular RNAs are endogenous non-coding RNAs that have been linked to the development of cancer. However, the role of circ_001569 in OS progression is still unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of circ_001569, microRNA-185-5p (miR-185-5p) and flotillin-2 (FLOT2). The abilities of cell proliferation, migration and invasion were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and Transwell assays, respectively. Also, western blot analysis was performed to assess the levels of epithelial–mesenchymal transition (EMT)-related proteins and FLOT2 protein. Besides, the dual-luciferase reporter assay was used to verify the interactions among circ_001569, miR-185-5p and FLOT2. Circ_001569 expression was increased in OS tissues and cells, and its knockdown reduced the proliferation, migration, invasion and EMT of OS cells. MiR-185-5p could interact with circ_001569. Inhibition of miR-185-5p could recover the suppression effects of silenced-circ_001569 on the proliferation and metastasis of OS cells. Furthermore, FLOT2 was a target of miR-185-5p. Overexpressed FLOT2 could restore the inhibition effects of miR-185-5p mimic on the proliferation and metastasis of OS cells. Also, FLOT2 expression was regulated by circ_001569 and miR-185-5p. In addition, circ_001569 knockdown also reduced the OS tumor growth in vivo. Circ_001569 might act as an oncogene in OS progression by regulating the miR-185-5p/FLOT2 axis, which provided a reliable new approach for the treatment of OS patients.

中文翻译：

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Circ_001569通过海绵miR-185-5p调节FLOT2表达促进骨肉瘤细胞的增殖、迁移、侵袭和EMT

摘要 骨肉瘤（OS）是世界范围内常见的恶性肿瘤。环状RNA是内源性非编码RNA，与癌症的发生有关。然而，circ_001569 在 OS 进展中的作用仍不清楚。采用实时定量聚合酶链反应（qRT-PCR）检测circ_001569、microRNA-185-5p（miR-185-5p）和flotillin-2（FLOT2）的表达。分别通过3-(4,5-二甲基-2-噻唑基)-2,5-二苯基-2-H-四唑溴化物(MTT)和Transwell实验评估细胞增殖、迁移和侵袭的能力。此外，还进行了蛋白质印迹分析以评估上皮-间质转化 (EMT) 相关蛋白和 FLOT2 蛋白的水平。此外，使用双荧光素酶报告基因测定来验证circ_001569、miR-185-5p和FLOT2之间的相互作用。Circ_001569在OS组织和细胞中表达增加，其敲除降低了OS细胞的增殖、迁移、侵袭和EMT。MiR-185-5p 可以与 circ_001569 相互作用。抑制miR-185-5p可以恢复沉默-circ_001569对OS细胞增殖和转移的抑制作用。此外，FLOT2 是 miR-185-5p 的靶标。过表达FLOT2可以恢复miR-185-5p模拟物对OS细胞增殖和转移的抑制作用。此外，FLOT2 表达受 circ_001569 和 miR-185-5p 调节。此外，circ_001569敲低还减少了体内OS肿瘤的生长。Circ_001569可能通过调节miR-185-5p/FLOT2轴作为OS进展中的癌基因，为OS患者的治疗提供了可靠的新方法。