title: Biophysical characterization and expression analysis of Kv1.3 potassium channel in primary human leukemic B cells.
abstract: OBJECTIVE
  Pharmacological inhibition of the potassium channel Kv1.3 has been shown to selectively kill B cells from patients with chronic lymphocytic leukemia (B-CLL). Here we aimed to biophysically characterize and compare Kv1.3 channel activity in B cells isolated either from healthy subjects or patients and investigated the mechanism accounting for the increased protein expression in B-CLL cells.
  
  
  METHODS
  Kv1.3 activity was measured by patch clamp, while expression of the channel protein was assessed by Western blot and FACS analysis. B-CLL cells were co-cultured with mesenchymal stromal cells (MSC) and Kv1.3 inhibitor-induced apoptosis was assessed.
  
  
  RESULTS
  We demonstrate that Kv1.3 is highly expressed and is more active at resting membrane potential in human B-CLL cells than in healthy cells. Channel expression in pathologic cells decreased by the B-RAF kinase inhibitor PLX-4720, while it increased with Doxazosin, an α1-adrenoceptor antagonist. Kv1.3 inhibitors induced death in B-CLL cells also when co-cultured with MSC.
  
  
  CONCLUSIONS
  Our results contribute to the characterization of B-CLL cells, as it shows that upregulation of Kv1.3 in pathologic B lymphocytes is linked to the oncogenic B-RAF signalling. We also conclude that Kv1.3 inhibitors represent a valuable tool to induce apoptosis of B-CLL cells even in the presence of MSC.
authors.affiliation: Department of Biology, University of Padua, Padua, Italy.
authors.forename: Ildiko
authors.initials: I
authors.lastname: Szabo
authors.forename: Livio
authors.initials: L
authors.lastname: Trentin
authors.forename: Valentina
authors.initials: V
authors.lastname: Trimarco
authors.forename: Gianpietro
authors.initials: G
authors.lastname: Semenzato
authors.forename: Luigi
authors.initials: L
authors.lastname: Leanza
mesh_terms: D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology / Q000473:pathology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D018920:Coculture Techniques; D003521:Cyclopropanes / Q000494:pharmacology; D017292:Doxazosin / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D019169:Jurkat Cells; D051664:Kv1.3 Potassium Channel / Q000378:metabolism*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism* / Q000503:physiopathology; D008564:Membrane Potentials / Q000187:drug effects; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D002934:Cinnamates; D003521:Cyclopropanes; D007211:Indoles; C496973:KCNA3 protein, human; D051664:Kv1.3 Potassium Channel; C528407:PLX 4720; D013449:Sulfonamides; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D017292:Doxazosin; C065310:igmesine