title: Trichostatin A sensitises rheumatoid arthritis synovial fibroblasts for TRAIL-induced apoptosis.
abstract: BACKGROUND
  Histone acetylation/deacetylation has a critical role in the regulation of transcription by altering the chromatin structure.
  
  
  OBJECTIVE
  To analyse the effect of trichostatin A (TSA), a streptomyces metabolite which specifically inhibits mammalian histone deacetylases, on TRAIL-induced apoptosis of rheumatoid arthritis synovial fibroblasts (RASF).
  
  
  METHODS
  Apoptotic cells were detected after co-treatment of RASF with TRAIL (200 ng/ml) and TSA (0.5, 1, and 2 micromol/l) by flow cytometry using propidium iodide/annexin-V-FITC staining. Cell proliferation was assessed using the MTS proliferation test. Induction of the cell cycle inhibitor p21Waf/Cip1 by TSA was analysed by western blot. Expression of the TRAIL receptor-2 (DR5) on the cell surface of RASF was analysed by flow cytometry. Levels of soluble TRAIL were measured in synovial fluid of patients with RA and osteoarthritis (OA) by ELISA.
  
  
  RESULTS
  Co-treatment of the cells with TSA and TRAIL induced cell death in a synergistic and dose dependent manner, whereas TRAIL and TSA alone had no effect or only a modest effect. RASF express DR5 (TRAIL receptor 2), but treatment of the cells with TSA for 24 hours did not change the expression level of DR5, as it is shown for cancer cells. TSA induced cell cycle arrest in RASF through up regulation of p21Waf1/Cip1. Levels of soluble TRAIL were significantly higher in RA than in OA synovial fluids.
  
  
  CONCLUSIONS
  Because TSA sensitises RASF for TRAIL-induced apoptosis, it is concluded that TSA discloses sensitive sites in the cascade of TRAIL signalling and may represent a new principle for the treatment of RA.
authors.affiliation: Centre of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Gloriastrasse 25, CH 8091 Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Jüngel
authors.forename: V
authors.initials: V
authors.lastname: Baresova
authors.forename: C
authors.initials: C
authors.lastname: Ospelt
authors.forename: B R
authors.initials: BR
authors.lastname: Simmen
authors.forename: B A
authors.initials: BA
authors.lastname: Michel
authors.forename: R E
authors.initials: RE
authors.lastname: Gay
authors.forename: S
authors.initials: S
authors.lastname: Gay
authors.forename: C A
authors.initials: CA
authors.lastname: Seemayer
authors.forename: M
authors.initials: M
authors.lastname: Neidhart
mesh_terms: D000368:Aged; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000494:pharmacology*; D001172:Arthritis, Rheumatoid / Q000378:metabolism / Q000473:pathology*; D015153:Blotting, Western / Q000379:methods; D002478:Cells, Cultured; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005260:Female; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005434:Flow Cytometry; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism / Q000473:pathology; D013583:Synovial Membrane / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D051017:Apoptosis Regulatory Proteins; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D006877:Hydroxamic Acids; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; C012589:trichostatin A