Circ_0003972 Promotes the Proliferation and Inflammation of Fibroblast-like Synovial Cells in Rheumatoid Arthritis through Regulation of the miR-654-5p/FZD4 Axis

Abstract

ABSTRACT Background Circular RNAs (circRNAs) have been shown to play an important role in rheumatoid arthritis (RA) progression. This study aims to explore the role and mechanism of circ_0003972 in RA progression. Methods Quantitative real-time PCR was used to determine gene expression. The proliferation and apoptosis of human RA fibroblast-like synovial (HFLS-RA) cells were measured using cell counting kit 8 assay, EdU staining and flow cytometry. Western blot analysis was performed to measure protein expression, and ELISA assay was used to examine the concentrations of inflammation factors. The interaction between miR-654-5p and circ_0003972 or FZD4 was confirmed by dual-luciferase reporter assay and RIP assay. Results Circ_0003972 was highly expressed in RA patients and HFLS-RA cells. Circ_0003972 knockdown inhibited the proliferation, inflammation, while promoted the apoptosis of TNFα-induced HFLS-RA cells. MiR-654-5p was downregulated in RA patients and HFLS-RA cells, and it could be sponged by circ_0003972. MiR-654-5p inhibitor reversed the effect of circ_0003972 silencing on the proliferation, inflammation, and apoptosis of TNFα-induced HFLS-RA cells. Frizzled-4 (FZD4) could be targeted by miR-654-5p, and its expression was positively regulated by circ_0003972. Furthermore, FZD4 overexpression also reversed the effects of miR-654-5p on proliferation, inflammation and apoptosis in TNFα-induced HFLS-RA cells. Conclusion Our data suggested that circ_0003972 might promote the proliferation and inflammation of HFLS-RA cells to accelerate RA progression via regulating miR-654-5p/FZD4.