Circ_0008410 contributes to fibroblast-like synoviocytes dysfunction by regulating miR-149-5p/HIPK2 axis.

Circular RNAs (circRNAs) play functional roles in rheumatoid arthritis (RA) progression. Fibroblast-like synoviocytes (RASFs) are the main effectors in RA development. In this study, we explored the function and mechanism of circ_0008410 in RASFs. qRT-PCR was used to detect the expression of circ_0008410, microRNA-149-5p (miR-149-5p), and homeodomain-interacting protein kinase 2 (HIPK2). Cell counting kit-8, EdU assay, flow cytometry, and transwell assay were performed to evaluate cell proliferation, apoptosis, migration, and invasion. Western blot measured the protein levels of related markers and HIPK2. The levels of IL-1β, TNF-α, and IL-6 were tested by corresponding ELISA kits and Western blot. The combination between miR-149-5p and circ_0008410 or HIPK2 was detected by dual-luciferase reporter assay or RNA immunoprecipitation (RIP) assay. Our data showed that circ_0008410 and HIPK2 were elevated, while miR-149-5p was downregulated in RA synovial tissues and RASFs. Circ_0008410 promoted RASF proliferation, migration, invasion, and inflammation while inhibiting apoptosis. MiR-149-5p was a target of circ_0008410, and its overexpression could reverse the promoting effects of circ_0008410 on RASF dysfunction. Moreover, miR-149-5p could target HIPK2 to suppress RASF proliferation, migration, invasion, and inflammation. Collectively, circ_0008410 promoted RASF dysfunction via miR-149-5p/HIPK2, which might provide a potential target for RA therapy.