These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Preferential inhibition of 5-trifluoromethyl-2'-deoxyuridine phosphorylation by 5'-amino-5'-deoxythymidine in uninfected versus herpes simplex virus-infected cells.
    Author: Fischer PH, Murphy DG, Kawahara R.
    Journal: Mol Pharmacol; 1983 Jul; 24(1):90-6. PubMed ID: 6408395.
    Abstract:
    The cytotoxic effects of 5-trifluoromethyl-2'-deoxyuridine (CF3dUrd) were effectively antagonized by 5'-amino-5'-deoxythymidine (5'-AdThd). The antiproliferative actions of CF3dUrd were reduced in a dose-dependent manner by 5'-AdThd in both HeLa and Vero cells. In addition, the ability of CF3dUrd to kill HeLa cells (95% at 1 microM and 99% at 3 microM), as measured by cloning efficiency, was ablated entirely by 5'-AdThd (300 microM). In contrast, the inhibition of herpes simplex virus Type 2 (HSV-2) replication in HeLa cells was not antagonized by 5'-AdThd. In Vero cells, the combination of CF3dUrd and 5'-AdThd produced a greater antiviral effect than either agent alone. The reduction in CF3dUrd cytotoxicity caused by 5'-AdThd in uninfected HeLa and Vero cells was associated with decreased intracellular levels of CF3dUrd nucleotides. In contrast, in HSV-2-infected Vero cells the intracellular levels of CF3dUrd nucleotides were slightly elevated by 5'-AdThd and, in virally infected HeLa cells, a 300-fold excess of 5'-AdThd reduced CF3dUrd uptake only marginally. Since the relative abundance of these phosphorylated derivatives of CF3dUrd was not markedly changed by 5'-AdThd, preferential inhibition of the mammalian thymidine kinase (EC 2.7.1.21) was suggested. Using CF3dUrd as the substrate, the ability of 5'-AdThd to inhibit thymidine kinase activity in extracts prepared from parallel cultures of mock-infected or HSV-2 infected HeLa cells was compared. CF3dUrd was phosphorylated to a lesser extent and the reaction was more potently inhibited by 5'-AdThd in the extracts prepared from the uninfected cells. The HeLa cell and HSV-2 thymidine kinases were purified by affinity column chromatography, and kinetic analyses were then done. Using CF3dUrd as the variable substrate, the Ki values for 5'-AdThd were 2.2 microM for the HeLa enzyme and 36 microM for the viral enzyme. Km values for CF3dUrd were 2.6 microM and 4 microM for the viral and mammalian enzymes, respectively. These data account for the ability of 5'-AdThd to inhibit preferentially the phosphorylation of CF3dUrd in uninfected host cells. The presence of 5'-AdThd substantially increased the therapeutic index of CF3dUrd, indicating that this drug combination, an example of specific inhibition, warrants investigation in vivo.
    [Abstract] [Full Text] [Related] [New Search]