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Functional Up-regulation of HERG K+ Channels in Neoplastic Hematopoietic Cells

Authors :
Lyanne C. Schlichter
Florence W. L. Tsui
Garth A.M. Smith
Evan W. Newell
Hing-Wo Tsui
Xiaoping Zhu
Xinpo Jiang
Source :
Journal of Biological Chemistry. 277:18528-18534
Publication Year :
2002
Publisher :
Elsevier BV, 2002.

Abstract

Kv1.3 channels regulate proliferation of normal lymphocytes, but the role of voltage-gated potassium channels in transformed hematopoietic cells is not known. We examined transcripts for Kv1.3, h-erg, h-eag, and BEC1 genes in primary lymphocytes and leukemias and in several hematopoietic cell lines. Surprisingly, BEC1, formerly thought to be brain-specific, was present in all the primary leukemias examined, in resting peripheral blood lymphocytes, and in proliferating activated tonsillar cells, lymphocytes from Sjögren's patients, and Epstein-Barr virus-transformed B-cells. Only h-erg mRNA was up-regulated in the cancer cells, but this was not due to proliferation per se, because it was not elevated in any of the proliferating noncancerous lymphocyte types examined. Nor did h-erg transcript levels correlate with the B-cell subset, because it was elevated in immature neoplastic B-CLL cells (CD5(+)) and in a CD5(-) Burkitt's lymphoma cell line (Raji) but not in Sjögren's syndrome cells (enriched in CD5(+) B-cells) or Epstein-Barr virus-transformed B-cells, which are mature CD5(-) B-cells. The protein and whole cell current levels roughly corresponded with the amount of mRNA expressed in three hematopoietic cell lines: CEM (an acute lymphoblastic leukemic line), K562 (a chronic myelogenous leukemic line), and U937 (an acute promyelocytic leukemic line). The selective HERG channel blocker, E-4031, reduced proliferation of CEM, U937, and K562 cells, and this appears to be the first direct evidence of a functional role for the HERG current in cancer cells. Selective up-regulation of h-erg appears to occur in neoplastic hematopoietic cells, thus providing a marker and potential therapeutic target.

Details

ISSN :
00219258
Volume :
277
Database :
OpenAIRE
Journal :
Journal of Biological Chemistry
Accession number :
edsair.doi.dedup.....a165e5b63ee65e0815ea4db23ba38750
Full Text :
https://doi.org/10.1074/jbc.m200592200