Abstract
Overexpression of FGF receptor 3 (FGFR3) is implicated in the development of t(4;14)-positive multiple myeloma. While FGFR3 is frequently overexpressed and/or activated through mutations in bladder cancer, the functional importance of FGFR3 and its potential as a specific therapeutic target in this disease have not been elucidated in vivo. Here we report that inducible knockdown of FGFR3 in human bladder carcinoma cells arrested cell-cycle progression in culture and markedly attenuated tumor progression in xenografted mice. Further, we developed a unique antibody (R3Mab) that inhibited not only WT FGFR3, but also various mutants of the receptor, including disulfide-linked cysteine mutants. Biochemical analysis and 2.1-A resolution crystallography revealed that R3Mab bound to a specific FGFR3 epitope that simultaneously blocked ligand binding, prevented receptor dimerization, and induced substantial conformational changes in the receptor. R3Mab exerted potent antitumor activity against bladder carcinoma and t(4;14)-positive multiple myeloma xenografts in mice by antagonizing FGFR3 signaling and eliciting antibody-dependent cell-mediated cytotoxicity (ADCC). These studies provide in vivo evidence demonstrating an oncogenic role of FGFR3 in bladder cancer and support antibody-based targeting of FGFR3 in hematologic and epithelial cancers driven by WT or mutant FGFR3.
MeSH terms
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Adaptor Proteins, Signal Transducing / metabolism
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Animals
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Antibodies, Monoclonal / immunology
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Antibodies, Monoclonal / pharmacology
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Antibodies, Monoclonal / therapeutic use*
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Antibody-Dependent Cell Cytotoxicity / immunology
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Antigen-Antibody Complex / chemistry
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Cell Line, Tumor / drug effects
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Cell Proliferation / drug effects
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Epitopes / chemistry
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Epitopes / immunology
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Female
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Fibroblast Growth Factors / metabolism
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Humans
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Membrane Proteins / metabolism
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Mice
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Mice, Nude
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Mice, SCID
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Mitogen-Activated Protein Kinases / metabolism
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Models, Molecular
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Multiple Myeloma / genetics
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Multiple Myeloma / pathology
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Multiple Myeloma / therapy*
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Phosphorylation / drug effects
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Protein Binding / drug effects
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Protein Conformation / drug effects
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RNA Interference
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Receptor, Fibroblast Growth Factor, Type 3 / antagonists & inhibitors
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Receptor, Fibroblast Growth Factor, Type 3 / immunology*
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Receptor, Fibroblast Growth Factor, Type 3 / metabolism
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Signal Transduction / drug effects
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Translocation, Genetic / genetics*
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Urinary Bladder Neoplasms / metabolism
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Urinary Bladder Neoplasms / pathology
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Urinary Bladder Neoplasms / therapy*
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Xenograft Model Antitumor Assays
Substances
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Adaptor Proteins, Signal Transducing
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Antibodies, Monoclonal
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Antigen-Antibody Complex
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Epitopes
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FRS2 protein, human
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Membrane Proteins
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Fibroblast Growth Factors
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FGFR3 protein, human
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Receptor, Fibroblast Growth Factor, Type 3
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Mitogen-Activated Protein Kinases