Sphingosine analogue drug FTY720 targets I2PP2A/SET and mediates lung tumour suppression via activation of PP2A-RIPK1-dependent necroptosis

Authors

  • Sahar A. Saddoughi,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Salih Gencer,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Yuri K. Peterson,

    1. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
    2. Department of Pharmaceutical Sciences, Medical University of South Carolina, Charleston, SC, USA
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  • Katherine E. Ward,

    1. Department of Chemistry and Biochemistry and the Mike and Josie Harper Center for Cancer Research, University of Notre Dame, Notre Dame, IN, USA
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  • Archana Mukhopadhyay,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Joshua Oaks,

    1. Human Cancer Genetics Program, Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University, Columbus, OH, USA
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  • Jacek Bielawski,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Zdzislaw M. Szulc,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Raquela J. Thomas,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Shanmugam P. Selvam,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Can E. Senkal,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Elizabeth Garrett-Mayer,

    1. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Ryan M. De Palma,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Dzmitry Fedarovich,

    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Angen Liu,

    1. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
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  • Amyn A. Habib,

    1. Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA
    2. North Texas Veterans Administration Medical Center, Dallas, TX, USA
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  • Robert V. Stahelin,

    1. Department of Chemistry and Biochemistry and the Mike and Josie Harper Center for Cancer Research, University of Notre Dame, Notre Dame, IN, USA
    2. Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, South Bend, IN, USA
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  • Danilo Perrotti,

    1. Human Cancer Genetics Program, Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University, Columbus, OH, USA
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  • Besim Ogretmen

    Corresponding author
    1. Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, USA
    2. Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
    • Tel: +1 843 792 0940; Fax: +1 843 792 2556

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Abstract

Mechanisms that alter protein phosphatase 2A (PP2A)-dependent lung tumour suppression via the I2PP2A/SET oncoprotein are unknown. We show here that the tumour suppressor ceramide binds I2PP2A/SET selectively in the nucleus and including its K209 and Y122 residues as determined by molecular modelling/simulations and site-directed mutagenesis. Because I2PP2A/SET was found overexpressed, whereas ceramide was downregulated in lung tumours, a sphingolipid analogue drug, FTY720, was identified to mimick ceramide for binding and targeting I2PP2A/SET, leading to PP2A reactivation, lung cancer cell death, and tumour suppression in vivo. Accordingly, while molecular targeting of I2PP2A/SET by stable knockdown prevented further tumour suppression by FTY720, reconstitution of WT-I2PP2A/SET expression restored this process. Mechanistically, targeting I2PP2A/SET by FTY720 mediated PP2A/RIPK1-dependent programmed necrosis (necroptosis), but not by apoptosis. The RIPK1 inhibitor necrostatin and knockdown or genetic loss of RIPK1 prevented growth inhibition by FTY720. Expression of WT- or death-domain-deleted (DDD)-RIPK1, but not the kinase-domain-deleted (KDD)-RIPK1, restored FTY720-mediated necroptosis in RIPK1−/− MEFs. Thus, these data suggest that targeting I2PP2A/SET by FTY720 suppresses lung tumour growth, at least in part, via PP2A activation and necroptosis mediated by the kinase domain of RIPK1.

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