OBJECTIVE

To clarify the effects of trichostatin A (TSA), a histone deacetylase inhibitor, on the growth and survival of rheumatoid arthritis synovial fibroblasts (RA-SF).

METHODS

Cell viability was assessed using a WST-8 assay and direct cell counting. Apoptosis was detected by annexin V staining on a flow cytometer. Protein and mRNA expression was determined by Western blotting, flow cytometry, and RT-PCR.

RESULTS

TSA suppressed cell growth of RA-SF in a dose-dependent manner, as determined by WST-8 assay and direct cell counting. Other histone deacetylase inhibitors also showed inhibitory effects on RA-SF proliferation. TSA upregulated p21(WAF1/CIP1) cell cycle inhibitor, suggesting that cell cycle arrest is involved in the reduction of cell numbers. In addition, TSA cooperated with Fas-induced pathway to induce cell death, determined by WST-8 assay and annexin V staining. TSA reduced FLICE inhibitory protein (FLIP) expression but not Bcl-2, Bcl-XL, and Fas expression, indicating that the synergistic effect may be through downregulation of FLIP.

CONCLUSIONS

TSA has antirheumatic effects on RA-SF and might be a potential therapeutic tool for the treatment of RA.