Hypoxanthine transport in human tumour cell lines: relationship to the inhibition of hypoxanthine rescue by dipyridamole. 2001

E Marshman, and G A Taylor, and H D Thomas, and D R Newell, and N J Curtin
Cancer Research Unit, Medical School, University of Newcastle upon Tyne, Framlington Place, NE2 4HH, Newcastle upon Tyne, UK.

Hypoxanthine (HPX) uptake was investigated in four human tumour cell lines previously characterised as being sensitive (ds: A549 and MCF7) or insensitive (di: COR-L23 and T-47D) to dipyridamole (DP)-induced inhibition of HPX rescue from antipurine antifolate-induced growth inhibition. The aim of the study was to determine the mechanism underlying the differential sensitivity of HPX rescue to DP. The time-course of HPX uptake in the two ds cell lines was different in comparison to the two di cell lines. The initial rate of HPX uptake in the di cell lines was more rapid than in the ds cell lines such that at 60 sec the amount of HPX taken up by the former was 2-6 times higher than that taken up by the later. The K(t) and T(max) for HPX transport in di COR-L23 cells were 870 microM and 4.75 microM/10(6) cells/min and 1390 microM and 1.78 microM/10(6) cells/min in ds A549 cells. HPX transport was not sodium-dependent in these cells. Equilibrative nucleoside transporter 2 (ENT2)-mediated thymidine transport was also higher in di cells. DP inhibited HPX uptake into ds cell lines by > or =48% and by < or =20% in the di cell lines. Competition studies with HPX and thymidine transport via ENT2 indicated an overlap between nucleoside and nucleobase transport transporters in the breast cancer cell lines (MCF7 and T-47D). These studies showed that more rapid and extensive HPX uptake, as well as reduced sensitivity to DP inhibition, is associated with the inability of DP to prevent HPX rescue from antipurine antifolate-induced growth inhibition in certain human tumour cell lines.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D010726 Phosphodiesterase Inhibitors Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases. Phosphodiesterase Antagonists,Phosphodiesterase Inhibitor,Phosphoric Diester Hydrolase Inhibitors,Antiphosphodiesterases,Inhibitor, Phosphodiesterase
D002352 Carrier Proteins Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes. Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002455 Cell Division The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION. M Phase,Cell Division Phase,Cell Divisions,Division Phase, Cell,Division, Cell,Divisions, Cell,M Phases,Phase, Cell Division,Phase, M,Phases, M
D002851 Chromatography, High Pressure Liquid Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D004176 Dipyridamole A phosphodiesterase inhibitor that blocks uptake and metabolism of adenosine by erythrocytes and vascular endothelial cells. Dipyridamole also potentiates the antiaggregating action of prostacyclin. (From AMA Drug Evaluations Annual, 1994, p752) Antistenocardin,Apo-Dipyridamole,Cerebrovase,Cléridium,Curantil,Curantyl,Dipyramidole,Kurantil,Miosen,Novo-Dipiradol,Persantin,Persantine,Apo Dipyridamole,Novo Dipiradol
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004347 Drug Interactions The action of a drug that may affect the activity, metabolism, or toxicity of another drug. Drug Interaction,Interaction, Drug,Interactions, Drug
D005493 Folic Acid Antagonists Inhibitors of the enzyme, dihydrofolate reductase (TETRAHYDROFOLATE DEHYDROGENASE), which converts dihydrofolate (FH2) to tetrahydrofolate (FH4). They are frequently used in cancer chemotherapy. (From AMA, Drug Evaluations Annual, 1994, p2033) Antifolate,Antifolates,Dihydrofolate Reductase Inhibitor,Folic Acid Antagonist,Dihydrofolate Reductase Inhibitors,Folic Acid Metabolism Inhibitors,Acid Antagonist, Folic,Acid Antagonists, Folic,Antagonist, Folic Acid,Antagonists, Folic Acid,Inhibitor, Dihydrofolate Reductase,Inhibitors, Dihydrofolate Reductase,Reductase Inhibitor, Dihydrofolate,Reductase Inhibitors, Dihydrofolate
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man

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