Anne-Sophie Borowiec, Frédéric Hague, Halima Ouadid-Ahidouch, Fabrice Gouilleux, François Guerineau, Stéphanie Guénin, Kaiss Lassoued, Morad Roudbaraki, Noria Harir, Laboratoire de Physiologie Cellulaire : Canaux ioniques, inflammation et cancer - U 1003 (PHYCELL), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lille, Biologie des Plantes et Innovation - UR UPJV 3900 (BIOPI), Université de Picardie Jules Verne (UPJV), Génétique, immunothérapie, chimie et cancer (GICC), UMR 6239 CNRS [2008-2011] (GICC UMR 6239 CNRS), Université de Tours-Centre National de la Recherche Scientifique (CNRS), Rôle des canaux ioniques membranaires et du calcium intracellulaire dans la physiopathologie de la prostate, Université de Lille, Sciences et Technologies-Institut National de la Santé et de la Recherche Médicale (INSERM), Développement normal et pathologique des lymphocytes et signalisation, Université de Picardie Jules Verne (UPJV)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physiologie Cellulaire et Moléculaire - UR UPJV 4667 (LPCM), Université de Picardie Jules Verne (UPJV)-Transfrontalière BioEcoAgro - UMR 1158 (BioEcoAgro), Université d'Artois (UA)-Université de Liège-Université de Picardie Jules Verne (UPJV)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Université d'Artois (UA)-Université de Liège-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Picardie Jules Verne (UPJV)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Gouilleux, Fabrice
Previous work from our laboratory has shown that human ether a go-go (hEAG) K+ channels are crucial for breast cancer cell proliferation and cell cycle progression. In this study, we investigated the regulation of hEAG channels by an insulin-like growth factor-1 (IGF-1), which is known to stimulate cell proliferation. Acute applications of IGF-1 increased K+ current-density and hyperpolarized MCF-7 cells. The effects of IGF-1 were inhibited by hEAG inhibitors. Moreover, IGF-1 increased mRNA expression of hEAG in a time-dependent manner in parallel with an enhancement of cell proliferation. The MCF-7 cell proliferation induced by IGF-1 is inhibited pharmacologically by Astemizole or Quinidine or more specifically using siRNA against hEAG channel. Either mitogen-activated protein kinase (MAPK) or phosphatidylinositol 3-kinase (PI3K) are known to mediate IGF-1 cell proliferative signals through the activation of extracellular signal-regulated kinase 1/2 (Erk 1/2) and Akt, respectively. In MCF-7 cells, IGF-1 rapidly stimulated Akt phosphorylation, whereas IGF-1 had little stimulating effect on Erk 1/2 which seems to be constitutively activated. The application of wortmannin was found to block the effects of IGF-1 on K+ current. Moreover, the inhibition of Akt phosphorylation by the application of wortmannin or by a specific reduction of Akt kinase activity reduced the hEAG mRNA levels. Taken together, our results show, for the first time, that IGF-1 increases both the activity and the expression of hEAG channels through an Akt-dependent pathway. Since a hEAG channel is necessary for cell proliferation, its regulation by IGF-1 may thus play an important role in IGF-1 signaling to promote a mitogenic effect in breast cancer cells. J. Cell. Physiol. 212:690–701, 2007. © 2007 Wiley-Liss, Inc.