Abstract
Recent evidence supports a role for EphB receptor tyrosine kinases as tumour suppressors in colorectal and prostate cancer. However, it is unclear how these receptors inhibit cancer cell tumorigenicity - an activity that is highly unusual for a family of receptor tyrosine kinases. Here, we report that the EphB4 receptor can behave as a tumour suppressor in a mouse xenograft model of breast cancer when stimulated by its ligand, ephrin-B2. In breast cancer cells, EphB4 activates an antioncogenic pathway involving Abl family tyrosine kinases and the Crk adaptor protein. This Abl-Crk pathway inhibits breast cancer cell viability and proliferation in addition to motility and invasion, and also downregulates the pro-invasive matrix metalloprotease, MMP-2. Consistent with these effects, EphB4 and the Abl-Crk pathway are constitutively active in non-transformed mammary epithelial cells. These findings identify a novel Eph receptor signalling pathway with tumour-suppressor activity and predict that therapeutic intervention to activate EphB4 signalling will inhibit tumour progression.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Benzamides
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Breast Neoplasms / metabolism*
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Breast Neoplasms / pathology
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Breast Neoplasms / prevention & control
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Cell Line, Tumor
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Cell Movement / drug effects
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Cell Proliferation / drug effects
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Ephrin-B2 / genetics
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Ephrin-B2 / metabolism
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Ephrin-B2 / pharmacology
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Female
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Humans
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Imatinib Mesylate
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Immunoglobulin Fc Fragments / genetics
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Mammary Neoplasms, Experimental / metabolism
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Mammary Neoplasms, Experimental / pathology
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Mammary Neoplasms, Experimental / prevention & control
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Matrix Metalloproteinase 2 / metabolism
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Mice
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Mice, Inbred BALB C
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Mice, Nude
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Neoplasm Transplantation
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Piperazines / pharmacology
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Protein Kinase Inhibitors / pharmacology
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Proto-Oncogene Proteins c-abl / metabolism*
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Proto-Oncogene Proteins c-crk / metabolism*
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Pyrimidines / pharmacology
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Receptor, EphB4 / agonists
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Receptor, EphB4 / metabolism
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Receptor, EphB4 / physiology*
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Recombinant Fusion Proteins / pharmacology
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Signal Transduction / physiology*
Substances
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Benzamides
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Ephrin-B2
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Immunoglobulin Fc Fragments
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Piperazines
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Protein Kinase Inhibitors
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Proto-Oncogene Proteins c-crk
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Pyrimidines
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Recombinant Fusion Proteins
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Imatinib Mesylate
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Receptor, EphB4
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Proto-Oncogene Proteins c-abl
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Matrix Metalloproteinase 2