Abstract
Amplification of the Neu (ErbB-2 or HER-2) receptor tyrosine kinase occurs in 20 to 30% of human mammary carcinomas, correlating with a poor clinical prognosis. We have previously demonstrated that four (Y1144 Y1201, Y1227 and Y1253) of the five known Neu autophosphorylation sites can independently mediate transforming signals. The transforming potential of two of these mutants correlates with their capacity to recruit Grb2 directly to Y1144 (YB) or indirectly through Shc to Y1227 (YD). Here, we demonstrate that these transformation-competent neu mutants activate extracellular signal-regulated kinases and stimulate Ets-2-dependent transcription. Although the transforming potential of three of these mutants (YB, YD, and YE) was susceptible to inhibition by Rap1A, a genetic antagonist of Ras, the transforming potential of YC was resistant to inhibition by Rap1A. To further address the significance of these ErbB-2-coupled signaling molecules in induction of mammary cancers, transgenic mice expressing mutant Neu receptors lacking the known autophosphorylation sites (NYPD) or those coupled directly to either Grb2 (YB) or Shc (YD) adapter molecules were derived. In contrast to the NYPD strains, which developed focal mammary tumors after a long latency period with low penetrance, all female mice derived from YB and YD strains rapidly developed mammary tumors. Although female mice from several independent YB or YD lines developed mammary tumors, the YB strains developed lung metastases at substantially higher rates than the YD strains. These observations argue that Grb2 and Shc play important and distinct roles in ErbB-2/Neu-induced mammary tumorigenesis and metastasis.
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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Adaptor Proteins, Signal Transducing*
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Adaptor Proteins, Vesicular Transport*
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Alleles
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Animals
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Binding Sites
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Breast Neoplasms / etiology*
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Breast Neoplasms / metabolism*
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Cell Line
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Chromatography, Affinity
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DNA-Binding Proteins*
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Female
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GRB2 Adaptor Protein
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Glutathione Transferase / metabolism
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Humans
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Immunoblotting
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Kinetics
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Mammary Neoplasms, Animal / etiology*
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Mammary Neoplasms, Animal / metabolism*
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Mice
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Mice, Transgenic
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Mitogen-Activated Protein Kinases / metabolism
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Neoplasm Metastasis
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Phosphorylation
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Precipitin Tests
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Protein Structure, Tertiary
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Proteins / physiology*
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Proto-Oncogene Protein c-ets-2
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Proto-Oncogene Proteins / metabolism
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Rats
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Receptor, ErbB-2 / metabolism*
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Recombinant Fusion Proteins / metabolism
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Repressor Proteins*
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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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Terminal Repeat Sequences
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Time Factors
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Trans-Activators / metabolism
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Transcription Factors*
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Transcription, Genetic
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Transcriptional Activation
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Transfection
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rap1 GTP-Binding Proteins / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Adaptor Proteins, Vesicular Transport
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DNA-Binding Proteins
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ERF protein, human
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ETS2 protein, human
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Ets2 protein, mouse
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Ets2 protein, rat
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GRB2 Adaptor Protein
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GRB2 protein, human
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Grb2 protein, mouse
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Grb2 protein, rat
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Proteins
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Proto-Oncogene Protein c-ets-2
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Proto-Oncogene Proteins
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Recombinant Fusion Proteins
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Repressor Proteins
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SHC1 protein, human
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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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Trans-Activators
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Transcription Factors
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Glutathione Transferase
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Receptor, ErbB-2
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Mitogen-Activated Protein Kinases
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rap1 GTP-Binding Proteins