Discovery of alpha-aminoazaheterocycle-methylglyoxal adducts as a new class of high-affinity inhibitors of cystic fibrosis transmembrane conductance regulator chloride channels.
The cystic fibrosis transmembrane conductance regulator (CFTR) represents the main Cl(-) channel in the apical membrane of epithelial cells for cAMP-dependent Cl(-) secretion. Here we report on the synthesis and screening of a small library of nontoxic alpha-aminoazaheterocycle-methylglyoxal adducts, inhibitors of wild-type (WT) CFTR and G551D-, G1349D-, and F508del-CFTR Cl(-) channels. In whole-cell patch-clamp experiments of Chinese hamster ovary (CHO) cells expressing WT-CFTR, we recorded rapid and reversible inhibition of forskolin-activated CFTR currents in the presence of the adducts 5a and 8a,b at 10 pM concentrations. Using iodide efflux experiments, we compared concentration-dependent inhibition of CFTR with glibenclamide (IC(50) = 14.7 microM), 3-[(3-trifluoromethyl)phenyl]-5-[(4-carboxyphenyl-)methylene]-2-thioxo-4-thiazolidinone (CFTR(inh)-172) (IC(50) = 1.2 microM), and alpha-aminoazaheterocycle-methylglyoxal adducts and identified compounds 5a (IC(50) = 71 pM), 8a,b (IC(50) = 2.5 nM), and 7a,b (IC(50) = 3.4 nM) as the most potent inhibitors of WT-CFTR channels. Similar ranges of inhibition were also found when these compounds were evaluated on CFTR channels with the cystic fibrosis mutations F508del (in temperature-corrected human airway epithelial F508del/F508del CF15 cells)-, G551D-, and G1349D-CFTR (expressed in CHO and COS-7 cells). No effect of compound 5a was detected on the volume-regulated or calcium-regulated iodide efflux. Picomolar inhibition of WT-CFTR with adduct 5a was also found using a 6-methoxy-N-(3-sulfopropyl)-quinolinium fluorescent probe applied to the human tracheobronchial epithelial cell line 16HBE14o-. Finally, we found comparable inhibition by 5a or by CFTR(inh)-172 of forskolin-dependent short-circuit currents in mouse colon. To the best of our knowledge, these new nontoxic alpha-aminoazaheterocycle-methylglyoxal adducts represent the most potent compounds reported to inhibit CFTR chloride channels.
Routaboul
Christel
C
Département de Pharmacochimie Moléculaire, Université de Grenoble, Centre National de la Recherche Scientifique, Bât. E, rue de la Chimie, BP 53, 38041 Grenoble Cedex 9, France.
Norez
Caroline
C
Melin
Patricia
P
Molina
Marie-Carmen
MC
Boucherle
Benjamin
B
Bossard
Florian
F
Noel
Sabrina
S
Robert
Renaud
R
Gauthier
Chantal
C
Becq
Frédéric
F
Décout
Jean-Luc
JL
D000818:Animals; D016466:CHO Cells; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D006224:Cricetinae; D003412:Cricetulus; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000037:antagonists & inhibitors* / Q000235:genetics; D004594:Electrophysiology; D004847:Epithelial Cells; D006571:Heterocyclic Compounds / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D009154:Mutation; D018408:Patch-Clamp Techniques; D011765:Pyruvaldehyde / Q000737:chemistry / Q000494:pharmacology*; D020545:Respiratory Mucosa / Q000166:cytology; D013329:Structure-Activity Relationship
D018118:Chloride Channels; D006571:Heterocyclic Compounds; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D011765:Pyruvaldehyde