The tumour suppressor FOXO3 is a key regulator of mantle cell lymphoma proliferation and survival

Authors

  • Antònia Obrador-Hevia,

    1. Cancer Cell Biology Group, Institut Universitari d’Investigació en Ciències de la Salut (IUNICS)
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  • Margalida Serra-Sitjar,

    1. Cancer Cell Biology Group, Institut Universitari d’Investigació en Ciències de la Salut (IUNICS)
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  • José Rodríguez,

    1. Cancer Cell Biology Group, Institut Universitari d’Investigació en Ciències de la Salut (IUNICS)
    2. Hospital Universitario Severo Ochoa, Department of Internal Medicine, Leganés, Madrid, Spain
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  • Priam Villalonga,

    1. Cancer Cell Biology Group, Institut Universitari d’Investigació en Ciències de la Salut (IUNICS)
    2. Departament de Biologia Fonamental, Universitat de les Illes Balears, Palma, Illes Balears
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  • Silvia Fernández de Mattos

    1. Cancer Cell Biology Group, Institut Universitari d’Investigació en Ciències de la Salut (IUNICS)
    2. Departament de Biologia Fonamental, Universitat de les Illes Balears, Palma, Illes Balears
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S. Fernández de Mattos, Cancer Cell Biology Group, Edifici Cientificotècnic, Institut Universitari d’Investigació en Ciències de la Salut (IUNICS), Universitat de les Illes Balears, Crta Valldemossa km 7·5. E-07122 Palma, Illes Balears, Spain.
E-mail: silvia.fernandez@uib.es

Summary

The FOXO3 (Forkhead/winged helix box class O 3) transcription factor is a crucial regulator of haematopoietic cell fate that controls proliferation and apoptosis, among other processes. Despite the central role of FOXO3 as a tumour suppressor and phosphatidylinositol 3-kinase (PI3K)/AKT effector, little is known about its involvement in mantle cell lymphoma (MCL) biology. This study investigated the expression and activity of FOXO3 in MCL cell lines and in primary cultures. We analysed the expression of key FOXO regulators and targets, and studied the effect of modulators of FOXO function on cell viability and apoptosis. FOXO3 was constitutively inactivated in MCL cell lines, and showed cytoplasmic localization in patient-derived cells. PI3K and AKT, but not mammalian target of rapamycin (mTOR), inhibitors induced FOXO3 nuclear translocation and activation in correlation with their impact on MCL proliferation and survival. Moreover, FOXO3-defective cells were resistant to PI3K/AKT inhibitors. Reactivation of FOXO function with a nuclear export inhibitor had a profound effect on cell viability, consistent with FOXO3 nuclear accumulation. Interestingly, inhibition of FOXO3 nuclear export enhanced the effect of doxorubicin. Taken together, our results confirm that FOXO3 is a relevant regulator of proliferation and apoptosis in MCL, and suggest that reactivation of FOXO3 function might be a useful therapeutic strategy in MCL patients.

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