Abstract
The neu (c-erbB-2) proto-oncogene encodes a tyrosine kinase receptor that is overexpressed in 20 to 30% of human breast tumors. Herein, cyclin D1 protein levels were increased in mammary tumors induced by overexpression of wild-type Neu or activating mutants of Neu in transgenic mice and in MCF7 cells overexpressing transforming Neu. Analyses of 12 Neu mutants in MCF7 cells indicated important roles for specific C-terminal autophosphorylation sites and the extracellular domain in cyclin D1 promoter activation. Induction of cyclin D1 by NeuT involved Ras, Rac, Rho, extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38, but not phosphatidylinositol 3-kinase. NeuT induction of the cyclin D1 promoter required the E2F and Sp1 DNA binding sites and was inhibited by dominant negative E2F-1 or DP-1. Neu-induced transformation was inhibited by a cyclin D1 antisense or dominant negative E2F-1 construct in Rat-1 cells. Growth of NeuT-transformed mammary adenocarcinoma cells in nude mice was blocked by the cyclin D1 antisense construct. These results demonstrate that E2F-1 mediates a Neu-signaling cascade to cyclin D1 and identify cyclin D1 as a critical downstream target of neu-induced transformation.
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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Animals
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Binding Sites
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Carrier Proteins*
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Cell Cycle Proteins*
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Cell Transformation, Neoplastic / pathology*
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Cyclin D1 / antagonists & inhibitors
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Cyclin D1 / genetics
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Cyclin D1 / metabolism*
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DNA-Binding Proteins / metabolism
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E2F Transcription Factors
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E2F1 Transcription Factor
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Humans
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JNK Mitogen-Activated Protein Kinases
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MAP Kinase Signaling System*
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Mammary Glands, Animal / metabolism
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Mammary Glands, Animal / pathology
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Mice
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Mice, Nude
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Mice, Transgenic
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / metabolism
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Monomeric GTP-Binding Proteins / genetics
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Monomeric GTP-Binding Proteins / metabolism
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Mutation / genetics
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Promoter Regions, Genetic / genetics
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Proto-Oncogene Mas
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RNA, Antisense / genetics
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RNA, Antisense / physiology
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Receptor, ErbB-2 / antagonists & inhibitors
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Receptor, ErbB-2 / genetics
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Receptor, ErbB-2 / metabolism*
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Retinoblastoma-Binding Protein 1
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Sp1 Transcription Factor / metabolism
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Sp3 Transcription Factor
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Transcription Factor DP1
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Transcription Factors / metabolism*
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Transcriptional Activation
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Tumor Cells, Cultured
Substances
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Arid4a protein, mouse
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Carrier Proteins
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Cell Cycle Proteins
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DNA-Binding Proteins
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E2F Transcription Factors
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E2F1 Transcription Factor
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E2F1 protein, human
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E2f1 protein, mouse
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MAS1 protein, human
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Proto-Oncogene Mas
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RNA, Antisense
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Retinoblastoma-Binding Protein 1
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Sp1 Transcription Factor
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TFDP1 protein, human
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Tfdp1 protein, mouse
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Transcription Factor DP1
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Transcription Factors
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Cyclin D1
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Sp3 Transcription Factor
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Receptor, ErbB-2
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinases
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Monomeric GTP-Binding Proteins