PT  - JOURNAL ARTICLE
AU  - Ricardo De La Fuente
AU  - Wan Namkung
AU  - Aaron Mills
AU  - A. S. Verkman
TI  - Small-Molecule Screen Identifies Inhibitors of a Human Intestinal Calcium-Activated Chloride Channel
AID  - 10.1124/mol.107.043208
DP  - 2008 Mar 01
TA  - Molecular Pharmacology
PG  - 758--768
VI  - 73
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/73/3/758.short
4100  - http://molpharm.aspetjournals.org/content/73/3/758.full
SO  - Mol Pharmacol2008 Mar 01; 73
AB  - Calcium-activated chloride channels (CaCCs) are widely expressed in mammalian tissues, including intestinal epithelia, where they facilitate fluid secretion. Potent, selective CaCC inhibitors have not been available. We established a high-throughput screen for identification of inhibitors of a human intestinal CaCC based on inhibition of ATP/carbachol-stimulated iodide influx in HT-29 cells after lentiviral infection with the yellow fluorescent halide-sensing protein YFP-H148Q/I152L. Screening of 50,000 diverse, drug-like compounds yielded six classes of putative CaCC inhibitors, two of which, 3-acyl-2-aminothiophenes and 5-aryl-2-aminothiazoles, inhibited by >95% iodide influx in HT-29 cells in response to multiple calcium-elevating agonists, including thapsigargin, without inhibition of calcium elevation, calcium-calmodulin kinase II activation, or cystic fibrosis transmembrane conductance regulator chloride channels. These compounds also inhibited calcium-dependent chloride secretion in T84 human intestinal epithelial cells. Patch-clamp analysis indicated inhibition of CaCC gating, which, together with the calcium-calmodulin data, suggests that the inhibitors target the CaCC directly. Structure-activity relationships were established from analysis of more than 1800 analogs, with IC50 values of the best analogs down to ∼1 μM. Small-molecule CaCC inhibitors may be useful in pharmacological dissection of CaCC functions and in reducing intestinal fluid losses in CaCC-mediated secretory diarrheas. The American Society for Pharmacology and Experimental Therapeutics