title: Heregulin (HRG)-induced mitogenic signaling and cytotoxic activity of a HRG/PE40 ligand toxin in human breast cancer cells.
abstract: The heregulins (HRGs) are a family of growth factors that bind direction to erbB3 and erbB4 and induce tyrosine phosphorylation of erbB2 via receptor heterodimerization. Since erbB2, erbB3, and erbB4 (erbB2-4) are often overexpressed in human breast cancer cells, we produced recombinant HRGs and a HRG-based ligand toxin to investigate the signaling events triggered by HRGs and the ability of these ligands to specifically target such cells. Recombinant HRG beta 2 stimulated the tyrosine phosphorylation of erbB2-4 in ZR-75-1 human breast cancer cells. This was accompanied by the tyrosine phosphorylation of Shc and the formation of complexes between Shc and the adapter protein Grb2. Complexes were also detected between Shc and erbB2-4. However, GRb2 was detected in erbB2 and erbB4 but not erbB3 immunoprecipitates. Thus, these receptors exhibit mechanistic differences in their coupling to Ras signaling, and HRG beta 2 administration triggers multiple inputs into the Ras signaling pathway, involving receptor-Grb2, receptor-Shc, and Shc-Grb2 complexes. HRG beta 2 addition also stimulated the association of erbB3 with phosphatidylinositol-3-kinase. In accordance with the activation of key mitogenic signaling pathways, HRG beta 2 stimulated the proliferation of MCF-7 and T-47D human breast cancer cells. Moreover, when tested for the ability to stimulate cell cycle re-entry of T-47D cells arrested under serum-free conditions, HRG beta 2 was more effective than insulin, previously the most potent mitogen identified using this system. Finally, a HRG beta 2 PE40 ligand toxin was constructed and found to exhibit cytotoxic activity against human breast cancer cells overexpressing erbB3 alone or in combination with erbB4 and/or erbB2.
authors.affiliation: Co-operative Research Centre for Biopharmaceutical Research, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, New South Wales, Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Fiddes
authors.forename: P W
authors.initials: PW
authors.lastname: Janes
authors.forename: G M
authors.initials: GM
authors.lastname: Sanderson
authors.forename: S P
authors.initials: SP
authors.lastname: Sivertsen
authors.forename: R L
authors.initials: RL
authors.lastname: Sutherland
authors.forename: R J
authors.initials: RJ
authors.lastname: Daly
mesh_terms: D036002:ADP Ribose Transferases; D048868:Adaptor Proteins, Signal Transducing; D001427:Bacterial Toxins; D001483:Base Sequence; D001943:Breast Neoplasms; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003001:Cloning, Molecular; D017931:DNA Primers; D066246:ErbB Receptors / Q000378:metabolism*; D005098:Exotoxins / Q000096:biosynthesis / Q000494:pharmacology*; D005260:Female; D051380:GRB2 Adaptor Protein; D006023:Glycoproteins / Q000096:biosynthesis / Q000494:pharmacology*; D006801:Humans; D000922:Immunotoxins / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D020890:Neuregulin-1; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000494:pharmacology; D015183:Restriction Mapping; D015398:Signal Transduction / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D037521:Virulence Factors; D018909:src Homology Domains; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D048868:Adaptor Proteins, Signal Transducing; D001427:Bacterial Toxins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002352:Carrier Proteins; D017931:DNA Primers; D066246:ErbB Receptors; D005098:Exotoxins; D051380:GRB2 Adaptor Protein; D006023:Glycoproteins; D000922:Immunotoxins; D020890:Neuregulin-1; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D019000:Phosphotyrosine; D011506:Proteins; D011518:Proto-Oncogene Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; D011994:Recombinant Proteins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C495948:GRB2 protein, human; C087230:heregulin beta1; C587689:ERBB4 protein, human