title: Inhibition of nucleoside transport by protein kinase inhibitors.
abstract: Recently we reported that the pyridinylimidazole class of p38 mitogen-activated protein (MAP) kinase inhibitors potently inhibited the facilitated transport of nucleosides and nucleoside analogs in K562 cells. These compounds competed with the binding of nitrobenzylthioinosine (NBMPR) to K562 cells, consistent with inhibition of the NBMPR-sensitive equilibrative transporter (ENT1). In this study we examined a large number of additional protein kinase inhibitors for their effects on nucleoside transport. We find that incubation of K562 cells with tyrosine kinase inhibitors (AG825, AG1517, AG1478, STI-571), protein kinase C (PKC) inhibitors (staurosporine, GF 109203X, R0 31-8220, arcyriarubin A), cyclin-dependent kinase inhibitors (roscovitine, olomoucine, indirubin-3'-monoxime), or rapamycin resulted in a dose-dependent reduction of intracellular uptake of [3H]uridine. In contrast, neither the MAP kinase kinase inhibitors (U0126, PD 98059) nor the phosphatidyl inositol-3 kinase inhibitors (wortmannin, LY 294002) affected this process. Furthermore, both transient uptake and prolonged [3H]thymidine incorporation in K562 cells were inhibited by protein kinase inhibitors, inactive analogs of kinase inhibitors (R0 31-6045, SB202474), and NBMPR, independently of effects on cell proliferation as determined by MTT assay. These studies demonstrate that a wide variety of protein kinase inhibitors affect nucleoside uptake through selective inhibition of nucleoside transporters, independently of kinase inhibition.
authors.affiliation: Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Huang
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Wang
authors.forename: Susan B
authors.initials: SB
authors.lastname: Cogut
authors.forename: Beverly S
authors.initials: BS
authors.lastname: Mitchell
authors.forename: Lee M
authors.initials: LM
authors.lastname: Graves
mesh_terms: D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002352:Carrier Proteins / Q000737:chemistry / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020014:K562 Cells; D011741:Pyrimidine Nucleosides / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D013936:Thymidine / Q000037:antagonists & inhibitors / Q000378:metabolism; D014529:Uridine / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011741:Pyrimidine Nucleosides; C015482:protein kinase modulator; D017868:Cyclic AMP-Dependent Protein Kinases; D013936:Thymidine; D014529:Uridine