title: Specificity of the volume-activated amino acid efflux pathway in cultured human breast cancer cells.
abstract: It has been shown that cell swelling stimulates the efflux of taurine from MCF-7 and MDA-MB-231 cells via a pathway which has channel-like properties. The purpose of this study was to examine the specificity of the volume-activated taurine efflux pathway in both cell lines. A hyposmotic shock increased the efflux of glycine, L-alanine, AIB (α-aminoisobutyric acid), D-aspartate but not L-leucine from MDA-MB-231 and MCF-7 cells. It was evident that the time course of activation/inactivation of those amino acids whose efflux was affected by cell swelling was similar to that of volume-activated taurine efflux. The effect of exogenous ATP on swelling-induced glycine, AIB and D-aspartate efflux from MDA-MB-231 cells was similar to that found on taurine efflux. In addition, volume-activated AIB efflux from MDA-MB-231 cells, like that of swelling-induced taurine efflux, was inhibited by diiodosalicylate. Tamoxifen inhibited volume-activated taurine release from both MDA-MB-231 and MCF-7 cells. The results suggest that neutral and anionic α-amino acids are able to utilize the volume-activated taurine efflux pathway in both cell lines. The effect of tamoxifen on breast cancer growth may, in part, be related to perturbations in cell volume regulation.
authors: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Royal College, 204 George Street, Glasgow, G1 1XW, United Kingdom. Dtaurine@aol.com
authors: David B
authors: DB
authors: Shennan
authors: Jean
authors: J
authors: Thomson
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000409:Alanine / Q000187:drug effects / Q000378:metabolism; D000596:Amino Acids / Q000187:drug effects / Q000378:metabolism*; D000621:Aminoisobutyric Acids / Q000032:analysis / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D048429:Cell Size; D026603:D-Aspartic Acid / Q000378:metabolism; D005998:Glycine / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007463:Iodobenzoates; D007930:Leucine / Q000187:drug effects / Q000378:metabolism; D009994:Osmolar Concentration; D012459:Salicylates / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology; D013654:Taurine / Q000187:drug effects / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D000596:Amino Acids; D000621:Aminoisobutyric Acids; D007463:Iodobenzoates; D012459:Salicylates; D013629:Tamoxifen; C020891:3,5-diiodosalicylic acid; C100049:2-aminoisobutyric acid; D013654:Taurine; D026603:D-Aspartic Acid; D000255:Adenosine Triphosphate; D007930:Leucine; D000409:Alanine; D005998:Glycine