Searching for combinations of small-molecule correctors to restore f508del-cystic fibrosis transmembrane conductance regulator function and processing

• Published in: The Journal of pharmacology and experimental therapeutics Vol. 350; no. 3; pp. 624 - 634
• Main Authors: Boinot, Clément, Jollivet Souchet, Mathilde, Ferru-Clément, Romain, Becq, Frédéric
• Format: Journal Article
• Language: English
• Published: United States 01.09.2014
• Subjects: 1-Deoxynojirimycin - analogs & derivatives; 1-Deoxynojirimycin - pharmacology; Aminopyridines - pharmacology; Benzamides - pharmacology; Benzodioxoles - pharmacology; Cell Survival - drug effects; Cell Survival - physiology; Colforsin - pharmacology; Cystic Fibrosis Transmembrane Conductance Regulator - agonists; Cystic Fibrosis Transmembrane Conductance Regulator - antagonists & inhibitors; Cystic Fibrosis Transmembrane Conductance Regulator - physiology; Dose-Response Relationship, Drug; HeLa Cells; Humans; Thiazoles - pharmacology
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.114.214890

The mutated protein F508del-cystic fibrosis transmembrane conductance regulator (CFTR) failed to traffic properly as a result of its retention in the endoplasmic reticulum and functions as a chloride (Cl(-)) channel with abnormal gating and endocytosis. Small chemicals (called correctors) individually restore F508del-CFTR trafficking and Cl(-) transport function, but recent findings indicate that synergistic pharmacology should be considered to address CFTR defects more clearly. We studied the function and maturation of F508del-CFTR expressed in HeLa cells using a combination of five correctors [miglustat, IsoLAB (1,4-dideoxy-2-hydroxymethyl-1,4-imino-l-threitol), Corr4a (N-[2-(5-chloro-2-methoxy-phenylamino)-4'-methyl-[4,5']bithiazolyl-2'-yl]-benzamide), VX-809 [3-(6-(1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)cyclopropanecarboxamido)-3-methylpyridin-2-yl)benzoic acid], and suberoylamilide hydroxamic acid (SAHA)]. Using the whole-cell patch-clamp technique, the current density recorded in response to CFTR activators (forskolin + genistein) was significantly increased in the presence of the following combinations: VX-809 + IsoLAB; VX-809 + miglustat + SAHA; VX-809 + miglustat + IsoLAB; VX-809 + IsoLAB + SAHA; VX-809 + miglustat + IsoLAB + SAHA. These combinations restored the activity of F508del-CFTR but with a differential effect on the appearance of mature c-band of F508del-CFTR proteins. Focusing on the VX-809 + IsoLAB cocktail, we recorded a level of correction higher at 37°C versus room temperature, but without amelioration of the thermal instability of CFTR. The level of functional rescue with VX-809 + IsoLAB after 4 hours of incubation was maximal and similar to that obtained in optimal conditions of use for each compound (i.e., 24 hours for VX-809 + 4 hours for IsoLAB). Finally, we compared the stimulation of F508del-CFTR by forskolin or forskolin + VX-770 [N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide] with cells corrected by VX-809 + IsoLAB. Our results open new perspectives for the development of a synergistic polypharmacology to rescue F508del-CFTR and show the importance of temperature on the effect of correctors and on the level of correction, suggesting that optimized combination of correctors could lead to a better rescue of F508del-CFTR function.