title: Inhibition of cell division by interferons: Changes in the transport and intracellular metabolism of thymidine in human lymphoblastoid (Daudi) cells.
abstract: The Daudi line of human lymphoblastoid cells shows a high sensitivity towards growth inhibition by human interferons. In cells pretreated with 70 reference units/ml of an interferon preparation for 48 h, the incorporation of exogenous [3H]thymidine into DNA is inhibited by as much as 85%. We are investigating the extent to which this effect reflects a true inhibition of the rate of DNA synthesis or whether it may be caused by changes in the metabolic utilization of exogenous thymidine by the cells. Interferon treatment results in a 30% inhibition of the rate of membrane transport and a 60% decrease in the rate of phosphorylation of [3H]thymidine in vivo. The latter effect is due to a decrease in V of thymidine kinase without any change in the value of Km for this enzyme. In addition to these changes, incorporation of [3H]uridine into DNA, which occurs as a result of the intracellular conversion of this precursor into thymidine nucleotides, is also inhibited by 75%, whereas RNA labelling by [3H]uridine is decreased by only 15% in interferon-treated cells. Thus several different metabolic events associated with thymidine nucleotide metabolism and DNA synthesis in Daudi cells are disrupted by interferon treatment.
mesh_terms: D000293:Adolescent; D001692:Biological Transport / Q000187:drug effects; D002051:Burkitt Lymphoma / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D004261:DNA Replication / Q000187:drug effects; D006801:Humans; D007372:Interferons / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D010766:Phosphorylation; D012313:RNA / Q000096:biosynthesis; D013936:Thymidine / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism
chemical_list: D012313:RNA; D007372:Interferons; D013936:Thymidine; D014529:Uridine