Antidiarrheal efficacy of a quinazolin CFTR inhibitor on human intestinal epithelial cell and in mouse model of cholera

Abstract

Objective: This study aimed to evaluate the antidiarrheal efficacy and pharmacological properties of ethyl 2-(4-oxo-3-o-tolyl-3,4-dihydroquinazolin-2- ylthio)acetate (DQA) as an inhibitor of cystic fibrosis transmembrane conductance regulator protein (CFTR) both in vitro and in vivo. Materials and Methods: The effects of DQA on CFTR function and cell viability were investigated in Fisher rat thyroid (FRT) cells expressing human CFTR and human intestinal epithelial T84 cells by short-circuit current measurements and MTT assays, respectively. In vivo antidiarrheal efficacy of DQA was evaluated in a closed loop model of cholera in mice. Results: In permeabilized FRT cells, apical chloride current induced by CFTR agonists (10 M forskolin, 100 M CPT-cAMP, and 20 M apigenin) was inhibited by DQA with IC 50 ~ 20 M and complete inhibition at 200 M. The inhibitory effect was reversible and not associated with cytotoxicity to FRT cells (5-500 M DQA for 24 h). Likewise, DQA effectively inhibited both forskolin and cholera toxin-induced transepithelial chloride secretion in T84 cells. In mice, intraluminal injection of 100 M DQA reduced cholera toxin (1 g/closed loop)-induced intestinal fluid secretion by 85% without affecting intestinal fluid absorption. Conclusions: DQA represents a new class of small molecule CFTR inhibitor with potential application in treatment of cholera.