Abstract
A rodent oncogenic mutant of the Neu receptor tyrosine kinase is a useful experimental model because overexpression of the respective receptor, namely HER2/ErbB-2, in human malignancies is associated with relatively aggressive diseases. Here we show that the oncogenic form of Neu is constitutively associated with the product of the c-cbl proto-oncogene and is part of a large complex that includes the phosphoinositide 3-kinase and Shc. Ectopic expression of c-Cbl, a ubiquitin-protein isopeptide ligase specific to activated tyrosine kinases, causes rapid removal of Neu from the cell surface and severely reduces signaling downstream of oncogenic Neu. c-Cbl-induced down-regulation of Neu involves covalent attachment of ubiquitin molecules and requires the carboxyl-terminal domain of Neu. The negative effect of c-Cbl is antagonized by v-Cbl, a virus-encoded oncogenic truncated form of c-Cbl. In an in vivo model, infection of a Neu-transformed neuroblastoma with a c-Cbl-encoding retrovirus caused enhanced down-regulation of Neu and correlated with tumor retardation. Our results implicate c-Cbl in negative regulation of Neu and offer a potential target for treatment of HER2/ErbB-2-positive human malignancies.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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3T3 Cells
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Adaptor Proteins, Signal Transducing*
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Adaptor Proteins, Vesicular Transport*
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Animals
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Antibodies, Monoclonal / metabolism
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Biotinylation
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CHO Cells
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Cell Line
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Cricetinae
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DNA, Complementary / metabolism
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DNA-Binding Proteins / metabolism
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Down-Regulation
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Electrophoresis, Polyacrylamide Gel
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Fibroblasts / metabolism
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Humans
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Immunoblotting
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Ligases / metabolism
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Male
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Mice
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Mice, Nude
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Neoplasm Transplantation
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Neuroblastoma / metabolism
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Nuclear Proteins / metabolism
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphorylation
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Precipitin Tests
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Protein Structure, Tertiary
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Proteins / metabolism
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Proto-Oncogene Mas
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins / physiology*
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Proto-Oncogene Proteins c-cbl
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Rats
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Receptor, ErbB-2 / genetics
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Receptor, ErbB-2 / metabolism*
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Retroviridae / genetics
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Serum Response Factor
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Shc Signaling Adaptor Proteins
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Signal Transduction
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Src Homology 2 Domain-Containing, Transforming Protein 1
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Time Factors
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Transfection
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Ubiquitin-Protein Ligases
Substances
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Adaptor Proteins, Signal Transducing
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Adaptor Proteins, Vesicular Transport
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Antibodies, Monoclonal
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DNA, Complementary
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DNA-Binding Proteins
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MAS1 protein, human
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Nuclear Proteins
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Proteins
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Proto-Oncogene Mas
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Proto-Oncogene Proteins
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SHC1 protein, human
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Serum Response Factor
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Shc Signaling Adaptor Proteins
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Shc1 protein, mouse
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Shc1 protein, rat
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Src Homology 2 Domain-Containing, Transforming Protein 1
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Proto-Oncogene Proteins c-cbl
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Ubiquitin-Protein Ligases
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Receptor, ErbB-2
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Ligases
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CBL protein, human
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Cbl protein, mouse