Transcription-dependent epidermal growth factor receptor activation by hepatocyte growth factor.
The mechanisms and biological implications of coordinated receptor tyrosine kinase coactivation remain poorly appreciated. Epidermal growth factor receptor (EGFR) and c-Met are frequently coexpressed in cancers, including those associated with hepatocyte growth factor (HGF) overexpression, such as malignant astrocytoma. In a previous analysis of the HGF-induced transcriptome, we found that two EGFR agonists, transforming growth factor-alpha and heparin-binding epidermal growth factor-like growth factor (HB-EGF), are prominently up-regulated by HGF in human glioma cells. We now report that stimulating human glioblastoma cells with recombinant HGF induces biologically relevant EGFR activation. EGFR phosphorylation at Tyr(845) and Tyr(1068) increased 6 to 24 h after cell stimulation with HGF and temporally coincided with the induction of transforming growth factor-alpha (~5-fold) and HB-EGF (~23-fold) expression. Tyr(845) and Tyr(1068) phosphorylation, in response to HGF, was inhibited by cycloheximide and actinomycin D, consistent with a requirement for DNA transcription and RNA translation. Specifically, blocking HB-EGF binding to EGFR with the antagonist CRM197 inhibited HGF-induced EGFR phosphorylation by 60% to 80% and inhibited HGF-induced S-G(2)-M transition. CRM197 also inhibited HGF-induced anchorage-dependent cell proliferation but had no effect on HGF-mediated cytoprotection. These findings establish that EGFR can be activated with functional consequences by HGF as a result of EGFR ligand expression. This transcription-dependent cross-talk between the HGF receptor c-Met and EGFR expands our understanding of receptor tyrosine kinase signaling networks and may have considerable consequences for oncogenic mechanisms and cancer therapeutics.
Reznik
Thomas E
TE
The Kennedy Krieger Research Institute, Baltimore, MD 21205, USA.
Sang
Yingying
Y
Ma
Yongxian
Y
Abounader
Roger
R
Rosen
Eliot M
EM
Xia
Shuli
S
Laterra
John
J
D001426:Bacterial Proteins / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects; D004249:DNA Damage; D004789:Enzyme Activation / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D066257:Heparin-binding EGF-like Growth Factor; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; C587883:HBEGF protein, human; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016211:Transforming Growth Factor alpha; C028581:CRM197 (non-toxic variant of diphtheria toxin); D019000:Phosphotyrosine; D017228:Hepatocyte Growth Factor; D066246:ErbB Receptors; D020928:Mitogen-Activated Protein Kinases