Depletion of circ_0128846 ameliorates interleukin-1β-induced human chondrocyte apoptosis and inflammation through the miR-940/PTPN12 pathway

Previous evidence has suggested that circular RNA (circRNA) is abnormally expressed in osteoarthritis (OA). However, the underlying mechanism of circRNA in OA progression remains unclear. The study aims to reveal the mechanism of circ_0128846 regulating OA. Human chondrocytes (C28/I2 cells) were treated with interleukin-1β (IL-1β) to mimic an OA cell model. The expression levels of circ_0128846, miR-940 and protein tyrosine phosphatase 12 (PTPN12) were detected by qRT-PCR. Protein expression was checked by Western blotting. Cell viability, proliferation, and apoptosis were analyzed by a cell counting kit-8 assay, 5-Ethynyl-2′-deoxyuridine (EdU) assay and flow cytometry analysis, respectively. The production of tumor necrosis factor-α (TNF-α) and IL-6 was determined by an enzyme-linked immunosorbent assay (ELISA). The binding relationship between miR-940 and circ_0128846 or PTPN12 was identified by dual-luciferase reporter assay and RNA immunoprecipitation assay. Circ_0128846 and PTPN12 expression were significantly upregulated, whereas miR-940 was downregulated in the cartilage tissues of OA patients and IL-1β-treated C28/I2 cells compared with controls. IL-1β treatment inhibited C28/I2 cell proliferation and induced cell apoptosis and the production of inflammatory factors, TNF-α and IL-6; however, these effects were partly reversed after circ_0128846 depletion. In terms of mechanism, circ_0128846 acted as a miR-940 sponge, and miR-940 combined with PTPN12. Also, circ_0128846 depletion partly ameliorated IL-1β-induced C28/I2 cell disorders through miR-940. PTPN12 overexpression also partly relieved miR-940-mediated effects in IL-1β-treated C28/I2 cells. Further, circ_0128846 induced PTPN12 expression by interacting with miR-940. Circ_0128846 regulated human chondrocyte proliferation, apoptosis and inflammation through the miR-940/PTPN12 pathway in OA.