Differentiation of HL-60 cells by dimethylsulfoxide activates a Na(+)-dependent nucleoside transport system.
Uridine transport in undifferentiated HL-60 cells occurs primarily by facilitated diffusion, but a limited Na(+)-dependent process can be demonstrated (Km = 44 +/- 4.4 microM, Vmax = 0.13 +/- 0.01 microM/s). This latter transport system was inhibited by adenosine and inosine (Ki = 110 and 260 microM, respectively), whereas guanosine and thymidine were less effective (Ki = 1600 and 1200 microM, respectively). Dimethylsulfoxide (DMSO) caused a concentration-dependent decrease in facilitated uridine transport. This change was attributable to a decrease in the number of transporter molecules as determined by the binding of [3H]nitrobenzylthioinosine to cell membranes. Moreover, the Na(+)-dependent transport of uridine was enhanced by DMSO at a concentration of the polar solvent as low as 0.4%. When HL-60 cells were exposed to 1.0% DMSO, a marked increase in Na(+)-dependent uridine transport occurred within 72 hr, a time preceding maximum granulocytic differentiation. This change was attributable to an increase in transport affinity (Km = 1.54 +/- 0.65 microM), with no change in Vmax (Vmax = 0.13 +/- 0.02 microM/s). The consequence of these changes was the generation of a 3- to 4-fold increase in the intracellular concentration of uridine relative to the medium at a physiological concentration of 5 microM uridine. Similar increases in transport affinity were observed for adenosine, inosine, guanosine and thymidine in DMSO-differentiated HL-60 cells (Km values of 2 to 5 microM). These results complement our previous studies with phorbol 12-myristate 13-acetate, in which differentiation to a monocytic phenotype was also associated with enhanced Na(+)-dependent nucleoside transport.
Lee
C W
CW
Department of Physiology, National University of Singapore.
Sokoloski
J A
JA
Sartorelli
A C
AC
Handschumacher
R E
RE
D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002794:Choline / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004176:Dipyridamole / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D015473:Leukemia, Promyelocytic, Acute; D026901:Membrane Transport Proteins; D012263:Ribonucleosides / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014529:Uridine / Q000378:metabolism*
D002352:Carrier Proteins; D026901:Membrane Transport Proteins; D012263:Ribonucleosides; C065171:cif nucleoside transporter; D004176:Dipyridamole; D012964:Sodium; D002794:Choline; D014529:Uridine; D004121:Dimethyl Sulfoxide