title: Effects of Imatinib Mesylate (Gleevec) on human islet NF-kappaB activation and chemokine production in vitro.
abstract: OBJECTIVE
  Imatinib Mesylate (Gleevec) is a drug that potently counteracts diabetes both in humans and in animal models for human diabetes. We have previously reported that this compound in human pancreatic islets stimulates NF-κB signaling and islet cell survival. The aim of this study was to investigate control of NF-κB post-translational modifications exerted by Imatinib and whether any such effects are associated with altered islet gene expression and chemokine production in vitro.
  
  
  METHODS
  Human islets were either left untreated or treated with Imatinib for different timepoints. IκB-α and NF-κB p65 phosphorylation and methylation were assessed by immunoblot analysis. Islet gene expression was assessed using a commercial Pathway Finder microarray kit and RT-PCR. Islet chemokine production was determined by flow cytometric bead array analysis.
  
  
  RESULTS
  Human islet IκB-α and Ser276-p65 phosphorylation were increased by a 20 minute Imatinib exposure. Methylation of p65 at position Lys221 was increased after 60 min of Imatinib exposure and persisted for 3 hours. Microarray analysis of islets exposed to Imatinib for 4 hours revealed increased expression of the inflammatory genes IL-4R, TCF5, DR5, I-TRAF, I-CAM, HSP27 and IL-8. The islet release of IL-8 was augmented in islets cultured over night in the presence of Imatinib. Following 30 hours of Imatinib exposure, the cytokine-induced IκB-α and STAT1 phosphorylation was abolished and diminished, respectively. The cytokine-induced release of the chemokines MIG and IP10 was lower in islets exposed to Imatinib for 30 hours.
  
  
  CONCLUSIONS
  Imatinib by itself promotes a modest activation of NF-κB. However, a prolonged exposure of human islets to Imatinib is associated with a dampened response to cytokines. It is possible that Imatinib induces NF-κB preconditioning of islet cells leading to lowered cytokine sensitivity and a mitigated islet inflammation.
authors.affiliation: Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden. dariush.mokhtari@mcb.uu.se
authors.forename: Dariush
authors.initials: D
authors.lastname: Mokhtari
authors.forename: Tingting
authors.initials: T
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Lu
authors.forename: Nils
authors.initials: N
authors.lastname: Welsh
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D001549:Benzamides; D018925:Chemokines / Q000378:metabolism; D005434:Flow Cytometry; D055551:HSP27 Heat-Shock Proteins / Q000235:genetics; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D000068877:Imatinib Mesylate; D066298:In Vitro Techniques; D016209:Interleukin-8 / Q000235:genetics; D008745:Methylation / Q000187:drug effects; D000072000:NF-KappaB Inhibitor alpha; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001549:Benzamides; D018925:Chemokines; D055551:HSP27 Heat-Shock Proteins; D020672:I-kappa B Proteins; D016209:Interleukin-8; C000606204:NFKBIA protein, human; D010879:Piperazines; D011743:Pyrimidines; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C484406:TANK protein, human; D051996:Transcription Factor RelA; D000072000:NF-KappaB Inhibitor alpha; D000068877:Imatinib Mesylate