title: Protein Kinase C-Independent Inhibition of Organic Cation Transporter 1 Activity by the Bisindolylmaleimide Ro 31-8220.
abstract: Ro 31-8220 is a potent protein kinase C (PKC) inhibitor belonging to the chemical class of bisindolylmaleimides (BIMs). Various PKC-independent effects of Ro 31-8220 have however been demonstrated, including inhibition of the ATP-binding cassette drug transporter breast cancer resistance protein. In the present study, we reported that the BIM also blocks activity of the solute carrier organic cation transporter (OCT) 1, involved in uptake of marketed drugs in the liver, in a PKC-independent manner. Ro 31-8220, in contrast to other pan-PKC inhibitors such as staurosporine and chelerythrine, was thus shown to cis-inhibit uptake of the reference OCT1 substrate tetraethylammonium in OCT1-transfected HEK293 cells in a concentration-dependent manner (IC50 = 0.18 μM) and without altering membrane expression of OCT1. This blockage of OCT1 was also observed in human hepatic HepaRG cells that constitutionally express OCT1. It likely occurred through a mixed mechanism of inhibition. Ro 31-8220 additionally trans-inhibited TEA uptake in OCT1-transfected HEK293 cells, which likely discards a transport of Ro 31-8220 by OCT1. Besides Ro 31-8220, 7 additional BIMs, including the PKC inhibitor LY 333531, inhibited OCT1 activity, whereas 4 other BIMs were without effect. In silico analysis of structure-activity relationships next revealed that various molecular descriptors, especially 3D-WHIM descriptors related to total size, correspond to key physico-chemical parameters for inhibition of OCT1 activity by BIMs. In addition to activity of OCT1, Ro 31-8220 inhibited those of other organic cation transporters such as multidrug and toxin extrusion protein (MATE) 1 and MATE2-K, whereas, by contrast, it stimulated that of OCT2. Taken together, these data extend the nature of cellular off-targets of the BIM Ro 31-8220 to OCT1 and other organic cation transporters, which has likely to be kept in mind when using Ro 31-8220 and other BIMs as PKC inhibitors in experimental or clinical studies.
authors.affiliation: Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043, Rennes, France.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Mayati
authors.affiliation: Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043, Rennes, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bruyere
authors.affiliation: Centre de Pharmacocinétique, Technologie Servier, 25-27 rue Eugène Vignat, 45000, Orléans, France.
authors.forename: Amélie
authors.initials: A
authors.lastname: Moreau
authors.affiliation: Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043, Rennes, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Jouan
authors.affiliation: Centre de Pharmacocinétique, Technologie Servier, 25-27 rue Eugène Vignat, 45000, Orléans, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Denizot
authors.affiliation: Centre de Pharmacocinétique, Technologie Servier, 25-27 rue Eugène Vignat, 45000, Orléans, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Parmentier
authors.affiliation: Institut de Recherches en Santé, Environnement et Travail (IRSET), UMR INSERM U1085, Faculté de Pharmacie, 2 Avenue du Pr Léon Bernard, 35043, Rennes, France.|Pôle Biologie, Centre Hospitalier Universitaire, 2 rue Henri Le Guilloux, 35033, Rennes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Fardel
mesh_terms: D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008301:Maleimides / Q000494:pharmacology*; D018613:Microscopy, Confocal; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D027702:Organic Cation Transporter 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000075102:Organic Cation Transporter 2; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D019789:Tetraethylammonium / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; D027701:Organic Cation Transport Proteins; D027702:Organic Cation Transporter 1; D000075102:Organic Cation Transporter 2; C491013:SLC22A2 protein, human; C521869:SLC47A1 protein, human; C521870:SLC47A2 protein, human; D049452:Green Fluorescent Proteins; D019789:Tetraethylammonium; C099154:ruboxistaurin; D011493:Protein Kinase C; C088060:bisindolylmaleimide; C064758:Ro 31-8220