Potential role of HER2-overexpressing exosomes in countering trastuzumab-based therapy

Authors

  • Valentina Ciravolo,

    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Veronica Huber,

    1. Unit of Immunotherapy of Human Tumors, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Gaia C. Ghedini,

    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Elisabetta Venturelli,

    1. Etiological and Preventive Epidemiology Unit, Department of Preventive and Predictive Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Francesca Bianchi,

    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Manuela Campiglio,

    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Daniele Morelli,

    1. Laboratory Medicine Unit, Department of Pathology and Laboratory, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Antonello Villa,

    1. Microscopy and Image Analysis Consortium, University of Milano-Bicocca, Monza, Italy
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  • Pamela Della Mina,

    1. Unit of Immunotherapy of Human Tumors, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
    2. Microscopy and Image Analysis Consortium, University of Milano-Bicocca, Monza, Italy
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  • Sylvie Menard,

    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Paola Filipazzi,

    1. Unit of Immunotherapy of Human Tumors, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Licia Rivoltini,

    1. Unit of Immunotherapy of Human Tumors, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Elda Tagliabue,

    Corresponding author
    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
    • Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale dei Tumori, Via Venezian 1, Milan, Italy.
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  • Serenella M. Pupa

    1. Molecular Targeting Unit, Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS, Istituto Nazionale Tumori, Milan, Italy
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  • Valentina Ciravolo and Veronica Huber contributed equally to this study.

Abstract

Exosomes are endosome-derived nanovesicles actively released into the extracellular environment and biological fluids, both under physiological and pathological conditions, by different cell types. We characterized exosomes constitutively secreted by HER2-overexpressing breast carcinoma cell lines and analyzed in vitro and in vivo their potential role in interfering with the therapeutic activity of the humanized antibody Trastuzumab and the dual tyrosine kinase inhibitor (TKI) Lapatinib anti-HER2 biodrugs. We show that exosomes released by the HER2-overexpressing tumor cell lines SKBR3 and BT474 express a full-length HER2 molecule that is also activated, although to a lesser extent than in the originating cells. Release of these exosomes was significantly modulated by the growth factors EGF and heregulin, two of the known HER2 receptor-activating ligands and naturally present in the surrounding tumor microenvironment. Exosomes secreted either in HER2-positive tumor cell-conditioned supernatants or in breast cancer patients' serum bound to Trastuzumab. Functional assays revealed that both xenogeneic and autologous HER2-positive nanovesicles, but not HER2-negative ones, inhibited Trastuzumab activity on SKBR3 cell proliferation. By contrast, Lapatinib activity on SKBR3 cell proliferation was unaffected by the presence of autologous exosomes. Together, these findings point to the role of HER2-positive exosomes in modulating sensitivity to Trastuzumab, and, consequently, to HER2-driven tumor aggressiveness. J. Cell. Physiol. 227: 658–667, 2012. © 2011 Wiley Periodicals, Inc.

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