Abstract
We have used differential display PCR to search for mRNAs induced by delta Raf-1:ER, an estradiol-dependent form of Raf-1 kinase. Through this approach the gene encoding heparin-binding epidermal growth factor (HB-EGF) was identified as an immediate-early transcriptional target of oncogenic Raf kinases. Activation of delta Raf-1:ER and a conditional oncogenic form of B-Raf, delta B-RAF:ER, resulted in rapid and sustained induction of HB-EGF mRNA expression and secretion of mature HB-EGF from cells. Neutralizing anti-HB-EGF antisera prevented the delayed activation of the c-Jun amino-terminal kinases that is observed in cells transformed by delta Raf-1:ER. These results demonstrate that distinct signaling pathways can cross talk via the secretion of polypeptide growth factors. Furthermore, cells transformed by oncogenic Ras, which also induced HB-EGF expression, demonstrated a marked increase in sensitivity to the cytotoxic action of diphtheria toxin, for which the membrane anchored HB-EGF precursor acts as a cell-surface receptor.
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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Animals
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Base Sequence
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism
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Cell Line
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Cell Line, Transformed
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Cell Transformation, Neoplastic
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DNA Primers
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Diphtheria Toxin / pharmacology
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Epidermal Growth Factor / metabolism*
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Estradiol / pharmacology
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Gene Expression* / drug effects
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Genes, ras*
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Heparin / metabolism*
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Heparin-binding EGF-like Growth Factor
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Humans
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Intercellular Signaling Peptides and Proteins
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JNK Mitogen-Activated Protein Kinases
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Mice
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Mitogen-Activated Protein Kinases*
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Molecular Sequence Data
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Oncogene Proteins v-raf
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Oncogenes*
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Polymerase Chain Reaction / methods
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Protein Serine-Threonine Kinases / genetics*
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Protein-Tyrosine Kinases / genetics
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Proto-Oncogene Proteins / genetics*
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Proto-Oncogene Proteins c-jun / metabolism
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Proto-Oncogene Proteins c-raf
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RNA, Messenger / analysis
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RNA, Messenger / biosynthesis
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Receptors, Cell Surface / biosynthesis*
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Retroviridae Proteins, Oncogenic / genetics*
Substances
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DNA Primers
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Diphtheria Toxin
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HBEGF protein, human
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Hbegf protein, mouse
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Heparin-binding EGF-like Growth Factor
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Intercellular Signaling Peptides and Proteins
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-jun
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RNA, Messenger
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Receptors, Cell Surface
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Retroviridae Proteins, Oncogenic
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Estradiol
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Epidermal Growth Factor
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Heparin
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Protein-Tyrosine Kinases
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Oncogene Proteins v-raf
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-raf
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Calcium-Calmodulin-Dependent Protein Kinases
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinases