The Activation Of Natural Small-molecule Compounds To CFTR

Cystic fibrosis transmembrane conductance regulator is a cAMP-activated anion channelpermeable to Cl-and HCO₃^-, expressed widely in absorption and secretion epithelial cells.Reduced function of CFTR is involved in the most common lethal disease.Therefore CFTR isan attractive molecular therapeutic target in treating the above mentioned diseases. In recentyears, several selective CFTR regulators including both activators and inhibitors, especiallycompounds from the combinatorial library have been identified. But none seems to be idealfor therapeutic use in the CFTR-related diseases. Natural compounds attracted attentions andwere expected to be more beneficial than the combinatorial compounds in the treatment ofCFTR-related disease.Previously, in screening for CFTR activators from naturally occurringcompounds, we found a large number of CFTR potentiators including dehydrocostuslactone（DHC） and tangeretin. The aim of the present study was to investigate in more details theeffect of DHC and tangeretin on CFTR in cell-based experiments in Floustar, Ussingchambers and Patch clamp technologys. Our study provides two new leading compounds fordeveloping potential drugs for the treatment of CFTR-related diseases such as cystic fibrosisand bronchiectasis. We found DHC and tangeretin both dose-dependently potentiateswild-type CFTR Cl-channel activities which was reversed by the CFTR inhibitorCFTRinh-172and GlyH101. Maximal transepithelial Cl-secretion in CFTR expression FRTcells was stimulated by100μM DHC and100μM tangeretin. In the submucosal gland fluidsecretion stimulation determination method research, we discover that the two compoundsboth can quicken the speed of liquid secretion, which are further evidences of them as theactivators of CFTR. In the patch clamp assays, we found that40μM tangeretin can obviouslyheighten the open extent of CFTR chloride channel in FRT cells. Determination ofintracellular cAMP content showed that DHC modestly but significantly increased cAMPlevel in FRT cells, but cAMP elevation effects contributed little to DHC-stimulated iodideinflux. DHC also stimulated transepithelial Cl-secretion in ΔF508-CFTR expression FRTcells. Subsequent studies demonstrated that activation of CFTR by DHC and tangeretin areboth forskolin （FSK） dependent.DHC and tangeretin represent two new classes of CFTRactivators that may have therapeutic potential in CFTR-related diseases.