Circular RNA CircCDKN2B-AS_006 Promotes the Tumor-like Growth and Metastasis of Rheumatoid Arthritis Synovial Fibroblasts by Targeting the miR-1258/RUNX1 Axis.

Rheumatoid arthritis (RA) is an autoimmune polyarthritis in which synovial fibroblasts (SFs) play a major role in cartilage and bone destruction through tumor-like proliferation, migration, and invasion. Circular RNAs (circRNAs) have emerged as vital regulators for tumor progression. However, the regulatory role, clinical significance, and underlying mechanisms of circRNAs in RASF tumor-like growth and metastasis remain largely unknown. Differentially expressed circRNAs in synovium samples from patients with RA and patients with joint trauma were identified via RNA sequencing. Subsequently, in vitro and in vivo experiments were performed to investigate the functional roles of circCDKN2B-AS_006 in RASF proliferation, migration, and invasion. CircCDKN2B-AS_006 was upregulated in synovium samples from patients with RA and promoted the tumor-like proliferation, migration, and invasion of RASFs. Mechanistically, circCDKN2B-AS_006 was shown to regulate the expression of runt-related transcription factor 1 (RUNX1) by sponging miR-1258, influencing the Wnt/β-catenin signaling pathway, and promoting the epithelial-to-mesenchymal transition (EMT) in RASFs. Moreover, in the collagen-induced arthritis (CIA) mouse model, intra-articular injection of lentivirus-shcircCDKN2B-AS_006 was capable of alleviating the severity of arthritis and inhibiting the aggressive behaviors of SFs. Furthermore, the correlation analysis results revealed that the circCDKN2B-AS_006/miR-1258/RUNX1 axis in the synovium was correlated with the clinical indicators of RA patients. CircCDKN2B-AS_006 promoted the proliferation, migration, and invasion of RASFs by modulating the miR-1258/RUNX1 axis.