Circular RNA circ_0003423 Promotes Osteoarthritis Progression by Sponging miR-330-5p to Upregulate TWIST1-Mediated Chondrocyte Inflammation and Extracellular Matrix Degradation.

Osteoarthritis (OA) is a debilitating degenerative joint disease characterized by progressive articular cartilage destruction, persistent inflammation, and functional impairment. Circular RNAs (CireRNAs) have emerged as critical epigenetic regulators in OA pathogenesis; however, the precise functional role of Circ_0003423 in OA remains largely unexplored. This study aimed to elucidate the expression pattern, biological functions, and underlying molecular mechanism of Circ_0003423 in OA progression. Bioinformatic analysis of the GSE178724 dataset was performed to identify differentially expressed CircRNAs in OA cartilage. Circ_0003423 and miR-330-5p expression levels were quantified by QRT-PCR in IL-1β-stimulated chondrocytes. The interaction between Circ_0003423 and miR-330-5p, and between miR-330-5p and TWIST1, was validated by RNA pull-down and dual-luciferase reporter assays. Western blotting was employed to assess TWIST1, Collagen I, Collagen II, ADAMTS5, MMP3, MMP13, total NF-κB p65, and phosphorylated NF-κB p65 (p-NF-κB p65) expression. Chondrocyte proliferation and apoptosis were evaluated by CCK-8 and EdU assays and flow cytometry, respectively. Pro-inflammatory cytokine levels were measured by ELISA. An OA mouse model was established via destabilization of the medial meniscus (DMM), and Circ_0003423 was silenced by intra-articular injection of lentiviral shRNA to validate In vivo findings. Circ_0003423 was significantly upregulated in OA cartilage and IL-1β-stimulated chondrocytes. Silencing Circ_0003423 rescued IL-1β-induced proliferation inhibition, reduced apoptosis, attenuated pro-inflammatory cytokine secretion, and mitigated ECM degradation. Mechanistically, Circ_0003423 functioned as a ceRNA by directly sponging miR-330-5p, which targeted TWIST1 to activate downstream NF-κB signalling and upregulate ADAMTS5, MMP3, and MMP13, with concomitant collagen downregulation. Rescue experiments confirmed that miR-330-5p inhibition or TWIST1 overexpression abrogated the protective effects of circ_0003423 silencing. In vivo, circ_0003423 silencing upregulated miR-330-5p, suppressed TWIST1/NF-κB/MMP3/MMP13 activation, and alleviated cartilage degeneration, chondrocyte apoptosis, and inflammatory responses in DMM mice. Circ_0003423 drives OA progression by functioning as a ceRNA to sponge miR-330-5p, thereby de-repressing TWIST1 and activating downstream NF-κB signalling and MMP3/MMP13-mediated ECM destruction. Targeting circ_0003423 represents a promising therapeutic strategy for OA intervention.