title: Genistein stimulates duodenal HCO(3)(-) secretion through PI3K pathway in mice.
abstract: Genistein has been proposed as a promising pharmacotherapeutic for cystic fibrosis. We recently found that genistein stimulates murine duodenal HCO(3)(-) secretion through cystic fibrosis transmembrane conductance regulator (CFTR). The aim of the present study was to determine the intracellular signal pathways involved in genistein-stimulated duodenal HCO(3)(-) secretion. Murine duodenal mucosal HCO(3)(-) secretion was examined in vitro in Ussing chambers by the pH-stat technique. The results showed that neither cAMP-dependent signal pathway inhibitors MDL-12330A and KT-5720, nor cGMP signal pathway inhibitors NS2028 and KT5823, nor calcium signal pathway inhibitors verapamil and W-13, altered genistein-stimulated duodenal HCO(3)(-) secretion. In calcium-free solution, genistein-stimulated duodenal HCO(3)(-) secretion was not altered either. Vanadate, an inhibitor of protein tyrosine phosphatase, only partially inhibited genistein-stimulated duodenal HCO(3)(-) secretion. However, both wortmannin and LY294002, two structurally and mechanistically distinct phosphatidylinositol 3-kinase (PI3K) inhibitors, markedly inhibited genistein-stimulated duodenal HCO(3)(-) secretion. Genistein increased duodenal mucosal PI3K activity and induced the phosphorylation of Akt, a signaling molecule downstream of PI3K, which was again inhibited by wortmannin. Estrogen receptor antagonist, ICI182,780, also markedly inhibited genistein-stimulated duodenal HCO(3)(-) secretion and genistein-induced PI3K activity increase in duodenal mucosa. These results demonstrate that genistein stimulates duodenal HCO(3)(-) secretion mainly through estrogen receptor and PI3K-dependent pathway. These findings contribute to the understanding of the molecular mechanism of genistein-induced anion secretion and further pharmacotherapeutic development and use of genistein or related substances in the treatment of diseases of epithelial tissues.
authors.affiliation: Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, 563003, China. tuobiguang@yahoo.com.cn
authors.forename: Biguang
authors.initials: B
authors.lastname: Tuo
authors.forename: Guorong
authors.initials: G
authors.lastname: Wen
authors.forename: Penghong
authors.initials: P
authors.lastname: Song
authors.forename: Jingyu
authors.initials: J
authors.lastname: Xu
authors.forename: Xuemei
authors.initials: X
authors.lastname: Liu
authors.forename: Ursula
authors.initials: U
authors.lastname: Seidler
authors.forename: Hui
authors.initials: H
authors.lastname: Dong
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004386:Duodenum / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D004553:Electric Conductivity; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology*; D066298:In Vitro Techniques; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D001639:Bicarbonates; D002118:Calcium; D000242:Cyclic AMP; D006152:Cyclic GMP; D004791:Enzyme Inhibitors; D019833:Genistein; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017027:Protein Tyrosine Phosphatases; D051057:Proto-Oncogene Proteins c-akt; D011960:Receptors, Estrogen