title: Enhanced exposure of phosphatidylserine in human gastric carcinoma cells overexpressing the half-size ABC transporter BCRP (ABCG2).
abstract: Members of the ABC (ATP-binding cassette) transporter super-family are emerging to be involved in lipid transport. In the present study, we studied the organization of phospholipids in the plasma membrane of EPG85-257 human gastric carcinoma cells overexpressing BCRP (breast cancer resistance protein, ABCG-2), a half-size transporter belonging to the ABCG subfamily. A significantly increased plasma membrane association of the PS (phosphatidylserine)-binding probe FITC-Annexin V in comparison with control cells was observed. Treatment of BCRP -overexpressing cells with the inhibitor Tryprostatin A decreased FITC-Annexin V binding almost to the control level. This suggests an enhanced exposure of PS in BCRP -overexpressing cells, which is dependent on functional BCRP. A role of BCRP in the transverse distribution of lipids in the plasma membrane is supported by the increased outward transport of the lipid analogue C6- N -(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-PS in BCRP -overexpressing EPG85-257 cells and MCF-7 human breast cancer cells. As shown for BCRP -overexpressing EPG85-257 cells, enhanced outward redistribution of the lipid analogue is inhibited by Tryprostatin A as well as by reduction of BCRP expression on transfection with an anti- BCRP -ribozyme. We also observed an enhanced outward transport of C6- N -(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-phosphatidylcholine in BCRP -overexpressing EPG85-257 cells, suggesting that the influence of BCRP on transverse lipid organization is not highly specific.
authors.affiliation: Institute of Biology, Humboldt University Berlin, Invalidenstr. 43, 10115 Berlin, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Woehlecke
authors.forename: Antje
authors.initials: A
authors.lastname: Pohl
authors.forename: Nele
authors.initials: N
authors.lastname: Alder-Baerens
authors.forename: Hermann
authors.initials: H
authors.lastname: Lage
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrmann
mesh_terms: D009327:4-Chloro-7-nitrobenzofurazan / Q000031:analogs & derivatives* / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001692:Biological Transport; D002277:Carcinoma / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010713:Phosphatidylcholines / Q000378:metabolism; D010718:Phosphatidylserines / Q000032:analysis* / Q000378:metabolism; D013274:Stomach Neoplasms / Q000378:metabolism*; D014162:Transfection
chemical_list: C092351:1-palmitoyl-2-(6-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)caproyl)glycero-3-phosphoserine; C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D009363:Neoplasm Proteins; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; C044745:1-palmitoyl-2-(6-(N-(7-nitrobenz)-2-oxa-1,3-diazol-4-yl)aminocaproyl)phosphatidylcholine; D009327:4-Chloro-7-nitrobenzofurazan