title: MDR1a/1b gene silencing enhances drug sensitivity in rat fibroblast-like synoviocytes.
abstract: BACKGROUND
  Drug resistance mediated by P-glycoprotein (P-gp) is one of the major reasons for the failure of rheumatoid arthritis (RA) therapy with disease modifying anti-rheumatic drugs and glucocorticoids. In the present study, we aimed to investigate the in vitro effectiveness of small interfering RNA (siRNA) to render rat fibroblast-like synoviocytes (FLS) susceptible to drugs. We also attempted the electroporation-mediated transfer of siRNA against multidrug resistance (MDR) genes into rat knee joints.
  
  
  METHODS
  FLS were transfected with siRNAs corresponding to MDR1a and MDR1b genes. FLS were treated with dexamethasone (DEX) and lipopolysaccharide. The mRNA and protein levels of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1beta were measured. Both siRNAs were co-transduced into rat knee joints by an electroporation method and evaluated the target gene expressions in the synovium.
  
  
  RESULTS
  Each siRNA could sequence-specifically reduce the target gene expression by over 70% and effectively suppressed P-gp expression and function in the FLS. Both gene expression and protein production of the inflammatory cytokines in the cells transfected with siRNA were reduced by a greater amount compared to in control cells. The in vivo electroporation-mediated transduction of siRNA could significantly inhibit the target gene expressions.
  
  
  CONCLUSIONS
  MDR1a/1b gene silencing by siRNA could effectively inhibit P-gp in rat FLS, resulting in a significant enhancement of the anti-inflammatory effects of DEX. The in vivo siRNA transduction could successfully silence MDR gene expression in the rat synovium. These findings indicate that the siRNA targeting MDR gene could be a useful tool for treating refractory arthritis in RA.
authors: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors: Kuniaki
authors: K
authors: Honjo
authors: Kenji A
authors: KA
authors: Takahashi
authors: Osam
authors: O
authors: Mazda
authors: Tsunao
authors: T
authors: Kishida
authors: Masaharu
authors: M
authors: Shinya
authors: Daisaku
authors: D
authors: Tokunaga
authors: Yuji
authors: Y
authors: Arai
authors: Atsuo
authors: A
authors: Inoue
authors: Nobuyuki
authors: N
authors: Hiraoka
authors: Jiro
authors: J
authors: Imanishi
authors: Toshikazu
authors: T
authors: Kubo
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000172:deficiency* / Q000235:genetics*; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical; D018274:Electroporation; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013583:Synovial Membrane / Q000166:cytology* / Q000187:drug effects; D014161:Transduction, Genetic; D014162:Transfection
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D034741:RNA, Small Interfering; D003907:Dexamethasone