title: Osmoregulation of taurine efflux from cultured human breast cancer cells: comparison with volume activated Cl- efflux and regulation by extracellular ATP.
abstract: The properties and regulation of volume-activated taurine efflux from MDA-MB-231 and MCF-7 cells have been investigated. Volume-activated taurine release from both cell lines was almost completely inhibited by diidosalicylate. DIDS , was more effective at inhibiting swelling-induced taurine release from MCF-7 than from MDA-MB-231 cells. On the basis of comparing taurine, Cl(-) and I(-) efflux time courses, it appears that volume-activated taurine efflux does not utilize volume-sensitive anion channels in MDA-MB- 231 and MCF-7 cells. Extracellular ATP stimulated volume-activated taurine release from MDA-MB-231 cells but not from MCF-7 cells. The effect of ATP was mimicked by UTP and was dependent upon external calcium and inhibited by suramin. However, suramin inhibited volume-activated taurine efflux from both MDA-MB-231 and MCF-7 cells even in the absence of exogenously added ATP suggesting that it acts directly on the taurine efflux pathway and/or is inhibiting the effect of ATP released from the cells. Volume-activated taurine efflux from MDA-MB-231 cells was stimulated by ionomycin. In contrast, ionomycin had no effect on taurine release from MCF-7 cells. Adenosine also stimulated volume-activated taurine efflux from MDA-MB-231 cells. The results suggest that purines regulate taurine transport in MDA-MB- 231 cells via more than one type of receptor.
authors.affiliation: Department of Bioscience, Royal College, University of Strathclyde, Glasgow, Scotland, UK.
authors.forename: David B
authors.initials: DB
authors.lastname: Shennan
authors.forename: Jean
authors.initials: J
authors.lastname: Thomson
authors.forename: Iain F
authors.initials: IF
authors.lastname: Gow
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D018118:Chloride Channels / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007454:Iodides / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D009994:Osmolar Concentration; D013498:Suramin / Q000494:pharmacology; D013654:Taurine / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018118:Chloride Channels; D002712:Chlorides; D007454:Iodides; D013654:Taurine; D015759:Ionomycin; D013498:Suramin; D000255:Adenosine Triphosphate; D000241:Adenosine; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid