Aspirin promotes apoptosis and inhibits proliferation by blocking G(0)/G(1) into S phase in rheumatoid arthritis fibroblast-like synoviocytes via downregulation of JAK/STAT3 and NF-κB signaling pathway

Rheumatoid arthritis (RA) is a commonly occurring autoimmune disease. Its defining pathological characteristic is the excessive proliferation of fibroblast-like synoviocytes (FLS), which is similar to tumor cells and results in a range of clinical problems. As a commonly used antipyretic, analgesic and anti-inflammatory drug, aspirin is the first-line treatment for RA. However, its mechanism of action has not been well explained. The goal is to investigate the biological effects of aspirin on primary RA-FLS and its underlying mechanisms. In this experiment we treated cells with various concentrations of aspirin (0, DMSO, 1, 2, 5, 10 mM). Cell proliferation activity was detected with CCK-8 assays. Apoptosis and cell cycle distribution were detected via flow cytometry. Apoptosis and cell cycle-associated proteins (Bcl-2, Bax, PRAP1, Cyclin D1, P21), as well as the key proteins and their phosphorylation levels of the NF-κB and JAK/STAT3 signaling pathways, were detected via western blot analysis. Bioinformatics prediction revealed that aspirin was closely associated with cell proliferation and apoptosis, including the p53 and NF-κB signaling pathways. By stimulating with aspirin, cell viability decreased, while the proportion of apoptotic cells increased, and the number of cells arrested in the G(0)/G(1) phase increased in a dose-dependent manner. The expression of Bax increased with aspirin stimulation, while the levels of Bcl-2, PRAP1, Cyclin D1 and P21 decreased; p-STAT3, p-P65 and p-50 levels also decreased while STAT3, P65, P50, p-P105 and P105 remained unchanged. From our data, it can be concluded that aspirin is able to promote apoptosis and inhibit the proliferation of RA-FLS through blocking the JAK/STAT3 and NF-κB signaling pathways.