R-Flurbiprofen Traps Prostaglandins within Cells by Inhibition of Multidrug Resistance-Associated Protein-4

Int J Mol Sci. 2016 Dec 30;18(1):68. doi: 10.3390/ijms18010068.

Abstract

R-flurbiprofen is the non-COX-inhibiting enantiomer of flurbiprofen and is not converted to S-flurbiprofen in human cells. Nevertheless, it reduces extracellular prostaglandin E₂ (PGE₂) in cancer or immune cell cultures and human extracellular fluid. Here, we show that R-flurbiprofen acts through a dual mechanism: (i) it inhibits the translocation of cPLA to the plasma membrane and thereby curtails the availability of arachidonic acid and (ii) R-flurbiprofen traps PGE₂ inside of the cells by inhibiting multidrug resistance-associated protein 4 (MRP4, ABCC4), which acts as an outward transporter for prostaglandins. Consequently, the effects of R-flurbiprofen were mimicked by RNAi-mediated knockdown of MRP4. Our data show a novel mechanism by which R-flurbiprofen reduces extracellular PGs at physiological concentrations, particularly in cancers with high levels of MRP4, but the mechanism may also contribute to its anti-inflammatory and immune-modulating properties and suggests that it reduces PGs in a site- and context-dependent manner.

Keywords: MRP4; PGE2; cPLA2; flurbiprofen.

MeSH terms

  • A549 Cells
  • Arachidonic Acid / metabolism
  • Blotting, Western
  • Cell Line, Tumor
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cyclooxygenase Inhibitors / pharmacology
  • Dinoprostone / metabolism*
  • Flurbiprofen / chemistry
  • Flurbiprofen / pharmacology*
  • Gene Expression / drug effects
  • Group IV Phospholipases A2 / antagonists & inhibitors
  • Group IV Phospholipases A2 / metabolism
  • HeLa Cells
  • Humans
  • Interleukin-1beta / pharmacology
  • Multidrug Resistance-Associated Proteins / antagonists & inhibitors*
  • Multidrug Resistance-Associated Proteins / genetics
  • Multidrug Resistance-Associated Proteins / metabolism*
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Stereoisomerism
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • ABCC4 protein, human
  • Cyclooxygenase Inhibitors
  • Interleukin-1beta
  • Multidrug Resistance-Associated Proteins
  • Tumor Necrosis Factor-alpha
  • Arachidonic Acid
  • Flurbiprofen
  • Group IV Phospholipases A2
  • PLA2G4A protein, human
  • Dinoprostone