Characterization of a growth factor that binds exclusively to the erbB-2 receptor and induces cellular responses

R. Lupu, R. Colomer, B. Kannan, M. E. Lippman

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100 Scopus citations


The erbB-2 oncogene encodes a 185-kDa transmembrane protein that has been suggested to be a growth factor receptor. We have previously identified and purified a 30-kDa growth factor (gp30) that is a ligand for the p185(erbB-2) protein that at high concentrations induces growth inhibition of cells with erbB-2 amplification. We now report the purification and characterization of a protein from SKBr-3 human breast cancer cells with a molecular mass of 75 kDa (p75) that is a p185(erbB-2) ligand. An affinity column coupled to the extracellular domain of p185(erbB-2) was used for the purification. We found that p75 induced tyrosine phosphorylation of the erbB-2 oncoprotein, as determined by in vivo and in vitro phosphorylation and phosphoamino acid analysis. p75, as well as gp30, stimulated cell proliferation and colony formation of cells overexpressing erbB-2. The specificity of this effect was confirmed by showing that the antiproliferative effects of soluble erbB-2 extracellular domain were reversed by either p75 or gp30. p75 did not show binding to the epidermal growth factor receptor and had no growth effects on cells overexpressing epidermal growth factor receptor. These data show that SKBR-3 cells, which exhibit erbB-2 amplification and overexpression, secrete a growth factor that binds and activates p185(erbB-2) specifically.

Original languageEnglish (US)
Pages (from-to)2287-2291
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number6
StatePublished - 1992


  • breast carcinomas
  • growth factor
  • oncogene

ASJC Scopus subject areas

  • General


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