AUTHOR=Thaweewattanodom Janjira , Deachapunya Chatsri , Poonyachoti Sutthasinee 

TITLE=Kaempferol activates chloride secretion via the cAMP/PKA signaling pathway and expression of CFTR in T84 cells

JOURNAL=Frontiers in Pharmacology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1401273

DOI=10.3389/fphar.2024.1401273

ISSN=1663-9812

ABSTRACT=<p>Kaempferol is a flavonol identified as the most potent activator of chloride (Cl<sup>−</sup>) secretion among other flavonoids in airway epithelial cells. This study aimed to investigate the cellular mechanisms by which kaempferol stimulates Cl<sup>−</sup> secretion in the T84 human colon carcinoma cell line by Ussing chambers and voltage clamp technique. Bilateral addition of kaempferol (1–100 µM) increased short-circuit current (<italic>I</italic><sub><italic>sc</italic></sub>) in a concentration-dependent manner. Ion substitution of Cl<sup>−</sup> or CFTR inhibitors NPPB and glibenclamide or a Na<sup>+</sup>/K<sup>+</sup>/2Cl<sup>−</sup> cotransporter inhibitor bumetanide attenuated kaempferol-induced <italic>I</italic><sub><italic>sc</italic></sub> response. In permeabilized monolayers, selective channel inhibitors CFTRinh-172 and CaCCinh-A01 inhibited kaempferol-induced apical Cl<sup>−</sup> current (<italic>I</italic><sub><italic>Cl</italic></sub>), and K<sup>+</sup> blockers BaCl<sub>2</sub> and clotrimazole inhibited basolateral K<sup>+</sup> current (<italic>I</italic><sub><italic>Kb</italic></sub>). The kaempferol-induced <italic>I</italic><sub><italic>Cl</italic></sub> showed no additive effects with forskolin or 8cpt-cAMP. The kaempferol-induced <italic>I</italic><sub><italic>Cl</italic></sub> was mostly abolished by protein kinase A inhibitor H89, but not by tyrosine kinase inhibitors, AG490 and tyrphostin A23, or tyrosine phosphatase inhibitor vanadate. Treatment with kaempferol for 24 h increased the expression of CFTR protein as determined by the Western blot analysis. These results demonstrated that kaempferol activates Cl<sup>−</sup> secretion across T84 cells by activating the apical Cl<sup>−</sup> current and basolateral K<sup>+</sup> current. The mechanisms may involve the cAMP/PKA pathway and CFTR expression. Taken together, these findings reveal the beneficial effects of kaempferol to increase fluid secretion which can be used to treat constipation.</p>