Changes in the K+ current-density of MCF-7 cells during progression through the cell cycle: possible involvement of a h-ether.a-gogo K+ channel.
MCF-7 cells express voltage-activated K+ channels. In the present study, we used the patch-clamp and RT-PCR techniques to investigate the involvement of these channels during the cell cycle progression. The outward rectifier current (IK) recorded during depolarization was almost completely suppressed by the classical K+ channel blocker tetraethylammonium (TEA) in MCF-7 cells. TEA also inhibited cell proliferation, as measured with 3H-thymidine incorporation. Moreover, profound changes were observed in both the resting membrane potential (RMP) and IK during the release from the G0/G1 phase of the cell cycle. MCF-7 cells arrested in G0/G1 were depolarized (-26.3 +/- 10 mV, n = 30) and IK-density was small (9.4 +/- 5.6 pA/pF, n = 60) compared to cells progressing in the G1 phase (RMP = -60 +/- 7.9 mV; n = 35 and IK-density = 30.2 +/- 8.5 pA/pF; n = 76). IK was highly sensitive to Mg2+, astemizole and TEA (10 mM). Extracellular perfusion of 5 mM Mg2+ dramatically slowed the activation and perfusion of 2 microM astemizole inhibited both IK (20 +/- 3%) and cell proliferation (23%). Moreover, the h-EAG mRNA expression was modulated during the cell cycle. Thus, these data suggested that h-EAG K+ channels play a role in controlling the proliferation and/or cell cycle.
Ouadid-Ahidouch
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Laboratoire de Physiologie Cellulaire, INSERM, France. ouadid.pop@univ-lille1.fr
Le Bourhis
X
X
Roudbaraki
M
M
Toillon
R A
RA
Delcourt
P
P
Prevarskaya
N
N
D016589:Astemizole / Q000494:pharmacology; D001692:Biological Transport; D001943:Breast Neoplasms / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D004553:Electric Conductivity; D051638:Ether-A-Go-Go Potassium Channels; D005260:Female; D016193:G1 Phase / Q000187:drug effects; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D019789:Tetraethylammonium / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D051638:Ether-A-Go-Go Potassium Channels; D006131:Growth Inhibitors; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D019789:Tetraethylammonium; D016589:Astemizole; D011188:Potassium