Modulation of the inwardly rectifying potassium channel Kir4.1 by the pro-invasive miR-5096 in glioblastoma cells

Abstract

// Dominique Thuringer 1 , Gaetan Chanteloup 1 , Jonathan Boucher 2 , Nicolas Pernet 1, 3 , Christophe Boudesco 1 , Gaetan Jego 1, 3 , Aurelien Chatelier 2 , Patrick Bois 2 , Jessica Gobbo 1, 4 , Laurent Cronier 2 , Eric Solary 5 and Carmen Garrido 1, 3 1 INSERM, U1231, Faculty of Medicine, 21000 Dijon, France 2 CNRS ERL 7368, STIM Laboratory, 86022 Poitiers, France 3 University of Bourgogne-Franche-Comté, 21000 Dijon, France 4 CGFL, Department of Medical Oncology, 21000 Dijon, France 5 INSERM, U1170, Institut Gustave Roussy, 94508 Villejuif, France Correspondence to: Dominique Thuringer, email: dominique.thuringer@u-bourgogne.fr Keywords: K + current, exosome, migration, microRNA, filopodia Received: January 06, 2017      Accepted: March 22, 2017      Published: April 07, 2017 ABSTRACT Inwardly rectifying potassium channels (Kir), and especially the barium-sensitive Kir4.1 encoded by KCNJ10 , are key regulators of glial functions. A lower expression or mislocation of Kir4.1 is detected in human brain tumors. MicroRNAs participate in the regulation of ionic channels and associated neurologic disorders. Here, we analyze effects of miR-5096 on the Kir4.1 expression and function in two glioblastoma cell lines, U87 and U251. Using whole-cell patch-clamp and western-blot analysis, we show that cell loading with miR-5096 decreases the Kir4.1 protein level and associated K + current. Cell treatment with barium, a Kir4.1 blocker, or cell loading of miR-5096 both increase the outgrowth of filopodia in glioma cells, as observed by time-lapse microscopy. Knocking-down Kir4.1 expression by si RNA transfection similarly increased both filopodia formation and invasiveness of glioma cells as observed in Boyden chamber assay. MiR-5096 also promotes the release of extracellular vesicles by which it increases its own transfer to surrounding cells, in a Kir4.1-dependent manner in U251 but not in U87. Altogether, our results validate Kir4.1 as a miR-5096 target to promote invasion of glioblastoma cells. Our data highlight the complexity of microRNA effects and the role of K + channels in cancer.