title: An unexpected biochemical and functional interaction between gp130 and the EGF receptor family in breast cancer cells.
abstract: Oncostatin M (OSM), an interleukin-6 type cytokine, acts via the gp130 signaling receptor to inhibit proliferation and induce differentiation of breast cancer cells. EGF, a mitogen for breast cells, signals via EGFR/ErbB tyrosine kinase receptors which are implicated in breast cancer pathogenesis. Here we show paradoxically that EGF enhanced the OSM-induced inhibition of proliferation and induction of cellular differentiation in both estrogen receptor positive and negative breast cancer cells. This functional synergism was also seen with heregulin but not SCF, PDGF or IGF-1, indicating that it was specific to EGF-related growth factors. Immunoprecipitation experiments revealed that gp130 was constitutively associated with ErbB-2 and ErbB-3. There was a similar association between the OSMRbeta and ErbB-2. Furthermore, EGF unexpectedly induced tyrosine phosphorylation of gp130. We show that OSM induced phosphorylation of STAT3. Both OSM and EGF activated the p42/44 MAP kinases, but while the MEK inhibitor, PD98059, ablated the OSM-induced inhibition, it only partially ablated the inhibitory effects of OSM plus EGF. Thus, we have demonstrated that the receptors and signalling pathways of two apparently unrelated growth factors were intimately linked, resulting in an unexpected biological effect. This provides a new mechanism for generating signalling diversity and has potential clinical implications in breast cancer.
authors.affiliation: The Rotary Bone Marrow Research Laboratories, PO Royal Melbourne Hospital, Parkville, Victoria, 3050, Australia. suzieg@ichr.uwa.edu.au
authors.forename: Susan L
authors.initials: SL
authors.lastname: Grant
authors.forename: Annet
authors.initials: A
authors.lastname: Hammacher
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Douglas
authors.forename: Geraldine A
authors.initials: GA
authors.lastname: Goss
authors.forename: Rachel K
authors.initials: RK
authors.lastname: Mansfield
authors.forename: John K
authors.initials: JK
authors.lastname: Heath
authors.forename: C Glenn
authors.initials: CG
authors.lastname: Begley
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D050822:Cytokine Receptor gp130; D004268:DNA-Binding Proteins / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D053683:Oncostatin M; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics; D050796:STAT3 Transcription Factor; D013379:Substrate Specificity; D015534:Trans-Activators / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D050822:Cytokine Receptor gp130; D004268:DNA-Binding Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D008562:Membrane Glycoproteins; D020929:Mitogen-Activated Protein Kinase Kinases; D053683:Oncostatin M; D010455:Peptides; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D011960:Receptors, Estrogen; D050796:STAT3 Transcription Factor; D015534:Trans-Activators; C494199:IL6ST protein, human; C508351:OSM protein, human; C494086:STAT3 protein, human