• Eur. J. Cancer · Jul 2004

    Positive interactive radiosensitisation in vitro with the combination of two nucleoside analogues, (E)-2'-deoxy-2'-(fluoromethylene) cytidine and iododeoxyuridine.

    • Philippe A Coucke, E Cottin, David Azria, Pierre Martineau, Florence Adamer, Laurent A Decosterd, Franz Buchegger, and Huu Phuoc Do.
    • Department of Radiation Oncology, Laboratory of Radiation Biology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. p.coucke@lausanne.com
    • Eur. J. Cancer. 2004 Jul 1; 40 (10): 1572-80.

    Abstract(E)-2'-Deoxy-2'-(fluoromethylene) cytidine (FMdC), an inhibitor of ribonucleotide diphosphate reductase (RR), is a potent radiation-sensitiser acting through alterations in the deoxyribonucleoside triphosphate (dNTP) pool in the de novo pathway to DNA synthesis. The activity of thymidine kinase (TK), a key enzyme in the 'salvage pathway', is known to increase in response to a lowering of dATP induced by FMdC. Nucleoside analogues such as iododeoxyuridine (IdUrd) are incorporated into DNA after phosphorylation by TK. Radiation sensitisation by IdUrd depends on IdUrd incorporation. Therefore, we have investigated the radiosensitising effect of the combination of FMdC and IdUrd on WiDr (a human colon cancer cell-line) and compared it to the effect of either drug alone. We analysed the effects of FMdC and IdUrd on the dNTP pools by high-performance liquid chromatography, and measured whether the incorporation of IdUrd was increased by FMdC using a [(125)I]-IdUrd incorporation assay. The combination in vitro yielded radiation-sensitiser enhancement ratios of >2, significantly higher than those observed with FMdC or IdUrd alone. Isobologram analysis of the combination indicated a supra-additive effect. This significant increase in radiation sensitivity with the combination of FMdC and IdUrd could not be explained by changes in the dNTP pattern since the addition of IdUrd to FMdC did not further reduce the dATP. However, the increase in the radiation sensitivity of WiDr cells might be due to increased incorporation of IdUrd after FMdC treatment. Indeed, a specific and significant incorporation of IdUrd into DNA could be observed with the [(125)I]-IdUrd incorporation assay in the presence of 1 microM unlabelled IdUrd when combined with FMdC treatment.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…