Biophysical characterization and expression analysis of Kv1.3 potassium channel in primary human leukemic B cells.

Abstract

BACKGROUND/AIMS:

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.

CONCLUSION:

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: Ildiko Szabo, Livio Trentin, Valentina Trimarco, Gianpietro Semenzato, Luigi Leanza
• Journal: Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology (Cell Physiol Biochem) Vol. 37 Issue 3 Pg. 965-78 ( 2015) ISSN: 1421-9778 [Electronic] Germany
• PMID: 26393354 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 S. Karger AG, Basel.

Chemical References

• Cinnamates
• Cyclopropanes
• Indoles
• KCNA3 protein, human
• Kv1.3 Potassium Channel
• PLX 4720
• Sulfonamides
• BRAF protein, human
• Proto-Oncogene Proteins B-raf
• Doxazosin
• igmesine

Topics

• Apoptosis
• B-Lymphocytes (cytology, pathology)
• Cell Proliferation (drug effects)
• Cells, Cultured
• Cinnamates (pharmacology)
• Coculture Techniques
• Cyclopropanes (pharmacology)
• Doxazosin (pharmacology)
• Humans
• Indoles (pharmacology)
• Jurkat Cells
• Kv1.3 Potassium Channel (metabolism)
• Leukemia, Lymphocytic, Chronic, B-Cell (metabolism, physiopathology)
• Membrane Potentials (drug effects)
• Mesenchymal Stem Cells (cytology)
• Proto-Oncogene Proteins B-raf (metabolism)
• Signal Transduction (drug effects)
• Sulfonamides (pharmacology)
• Up-Regulation (drug effects)