Small-molecule screen identifies inhibitors of a human intestinal calcium-activated chloride channel

Ricardo De La Fuente, Wan Namkung, Aaron Mills, Alan S. Verkman

Research output: Contribution to journalArticlepeer-review

174 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)758-768
Number of pages11
JournalMolecular pharmacology
Issue number3
Publication statusPublished - 2008 Mar

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Pharmacology


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