Background An aggressive proliferation of synovium is the hallmark of rheumatoid arthritis (RA). Previous studies suggested that resistance of fibroblast-like synoviocytes (FLS) to apoptosis is involved in synovial hyperplasia in the patients with RA. Recently, the possibilities that autophagy regulates apoptosis resistance and hyperplasia of FLS were also presented. Selective cyclooxygenase-2 (COX-2) inhibitor, celecoxib, has been reported to affect apoptosis or autophagy in various cancer cells.
Objectives The aim of this study is to investigate the influence of celecoxib on viability of RAFLS and to reveal how celecoxib affects the viability of RAFLS.
Methods RA synovial tissue was obtained from patients during total knee replacement surgery or arthroscopy. FLS was cultured with celecoxib, caspase inhibitor (z-VAD-fmk) or autophagy inhibitor (3-methyladenine; 3-MA, bafilomycin A1; bafi A1, chloquine; CQ). Cell viability was measured by MTS assay and by cell count using trypan blue staining. The expression of autophagy flux (LC3, p62) and apoptosis related protein (caspase3 and poly (ADP-ribose) polymerases (PARP)) was analyzed by western blot.
Results Celecoxib dose-dependently decreased cell viability (mean IC50 of 120 μM) of RAFLS. Activation of Caspase 3 and PARP cleavage were observed in RAFLS after the treatment with celecoxib. Combination treatment with caspase inhibitor and celecoxib increased cell viability than a single treatment with celecoxib. Celecoxib also increased the expression of LC3II and p62 in RAFLS. Treatment with autophagy inhibitor (3-MA, bafi A1, CQ) restored viability of RAFLS which was decreased by celecoxib.
Conclusions This study demonstrates that both apoptosis and autophagy contribute to celecoxib-induced cell death in RAFLS. Further studies to identify the effects of celecoxib on chronological sequence of autophagy and apoptosis in RAFLS are need.
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Disclosure of Interest None declared