Synthetic lethality of PARP and NAMPT inhibition in triple-negative breast cancer cells

Authors

  • Ilirjana Bajrami,

    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
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  • Asha Kigozi,

    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
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  • Antoinette Van Weverwijk,

    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
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  • Rachel Brough,

    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
    2. Cancer Research UK Gene Function Laboratory, The Institute of Cancer Research, London, UK
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  • Jessica Frankum,

    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
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  • Christopher J. Lord,

    Corresponding author
    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
    • Christopher J. Lord, Tel: +44 0207 1535334; Fax: +44 0207 3523299

      Alan Ashworth, Tel: +44 0207 1535334; Fax: +44 0207 3523299

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  • Alan Ashworth

    Corresponding author
    1. The Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, UK
    2. Cancer Research UK Gene Function Laboratory, The Institute of Cancer Research, London, UK
    • Christopher J. Lord, Tel: +44 0207 1535334; Fax: +44 0207 3523299

      Alan Ashworth, Tel: +44 0207 1535334; Fax: +44 0207 3523299

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Abstract

PARP inhibitors have been proposed as a potential targeted therapy for patients with triple-negative (ER-, PR-, HER2-negative) breast cancers. However, it is as yet unclear as to whether single agent or combination therapy using PARP inhibitors would be most beneficial. To better understand the mechanisms that determine the response to PARP inhibitors, we investigated whether enzymes involved in metabolism of the PARP substrate, β-NAD+, might alter the response to a clinical PARP inhibitor. Using an olaparib sensitization screen in a triple-negative (TN) breast cancer model, we identified nicotinamide phosphoribosyltransferase (NAMPT) as a non-redundant modifier of olaparib response. NAMPT is a rate-limiting enzyme involved in the generation of the PARP substrate β-NAD+ and the suppression of β-NAD+ levels by NAMPT inhibition most likely explains these observations. Importantly, the combination of a NAMPT small molecule inhibitor, FK866, with olaparib inhibited TN breast tumour growth in vivo to a greater extent than either single agent alone suggesting that assessing NAMPT/PARP inhibitor combinations for the treatment of TN breast cancer may be warranted.

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