Induction of EMT-like phenotypes by an active metabolite of leflunomide and its contribution to pulmonary fibrosis

Cell Death Differ. 2010 Dec;17(12):1882-95. doi: 10.1038/cdd.2010.64. Epub 2010 May 21.

Abstract

Drug-induced interstitial lung disease (ILD), particularly pulmonary fibrosis, is a serious clinical concern and myofibroblasts have been suggested to have a major role, with it recently being revealed that some of these myofibroblasts are derived from lung epithelial cells through epithelial-mesenchymal transition (EMT). In this study, we examined the EMT-inducing abilities of drugs known to induce ILD clinically. EMT-like phenotypes were induced by A771726, an active metabolite of leflunomide having an inhibitory effect on dihydroorotate dehydrogenase (DHODH). Smad-interacting protein 1 (a transcription factor regulating EMT) and the Notch-signaling pathway but not transforming growth factor-β was shown to be involved in A771726-induced EMT-like phenotypes. When the cultures were supplemented with exogenous uridine, the A771726-induced EMT-like phenotypes and activation of the Notch-signaling pathway disappeared. Similarly, an A771726 analog without inhibitory activity on DHODH produced no induction, suggesting that this process is mediated through the inhibition of DHODH. In vivo, administration of leflunomide stimulated bleomycin-induced EMT-like phenomenon in pulmonary tissue, and exacerbated bleomycin-induced pulmonary fibrosis, both of which were suppressed by coadministration of uridine. Taken together, these findings suggest that leflunomide-dependent exacerbation of bleomycin-induced pulmonary fibrosis is mediated by stimulation of EMT of lung epithelial cells, providing the first evidence that drug-induced pulmonary fibrosis involves EMT of these cells.

MeSH terms

  • Aniline Compounds / chemistry
  • Aniline Compounds / pharmacology*
  • Aniline Compounds / therapeutic use
  • Animals
  • Bleomycin / pharmacology
  • Cells, Cultured
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology
  • Epithelial-Mesenchymal Transition / drug effects*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Hydroxybutyrates / chemistry
  • Hydroxybutyrates / pharmacology*
  • Hydroxybutyrates / therapeutic use
  • Hydroxyproline / metabolism
  • Mice
  • Oxidoreductases Acting on CH-CH Group Donors / antagonists & inhibitors
  • Oxidoreductases Acting on CH-CH Group Donors / metabolism
  • Phenotype
  • Pulmonary Fibrosis / chemically induced
  • Pulmonary Fibrosis / drug therapy
  • Pulmonary Fibrosis / metabolism*
  • RNA Interference
  • RNA, Small Interfering
  • Rats
  • Receptors, Notch / metabolism
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Signal Transduction
  • Transforming Growth Factor beta / metabolism
  • Uridine / pharmacology
  • Zinc Finger E-box Binding Homeobox 2

Substances

  • Aniline Compounds
  • Enzyme Inhibitors
  • Homeodomain Proteins
  • Hydroxybutyrates
  • RNA, Small Interfering
  • Receptors, Notch
  • Repressor Proteins
  • Transforming Growth Factor beta
  • ZEB2 protein, human
  • Zinc Finger E-box Binding Homeobox 2
  • A 771726
  • Bleomycin
  • Oxidoreductases Acting on CH-CH Group Donors
  • dihydroorotate dehydrogenase
  • Hydroxyproline
  • Uridine