Additive effects of c-erbB-2, c-Ha-ras, and transforming growth factor-alpha genes on in vitro transformation of human mammary epithelial cells

Mol Carcinog. 1992;6(1):43-52. doi: 10.1002/mc.2940060108.


MCF-10A cells are a spontaneously immortalized untransformed human mammary epithelial cell line. We have previously shown that overexpression of a human point-mutated c-Ha-ras proto-oncogene, the rat c-neu (c-erbB-2) proto-oncogene, or the human transforming growth factor-alpha (TGF-alpha) gene in MCF-10A cells leads to in vitro transformation of such cells. To ascertain whether the introduction of two of these genes into MCF-10A human mammary epithelial cells induces a completely tumorigenic phenotype, we infected MCF-10A Ha-ras and MCF-10A TGF-alpha cells with a recombinant retroviral vector containing the human c-erbB-2 proto-oncogene and the hygromycin-resistance gene. Ten MCF-10A TGF-alpha/c-erbB-2 (MCF-10A TE) and 10 MCF-10A Ha-ras/c-erbB-2 (MCF-10A HE) hygromycin-resistant clones were randomly selected and expanded into cell lines. MCF-10A TE and MCF-10A HE clones expressed a 10-fold to 40-fold increase in p185 erbB-2 protein levels compared with parental uninfected cells. These cells exhibited a fourfold increase in their growth rate in serum-free medium and showed a strongly reduced mitogenic response to exogenous epidermal growth factor or TGF-alpha compared with MCF-10A cells. Moreover, both MCF-10A TE and MCF-10A HE clones exhibited a fivefold to 20-fold higher cloning efficiency in soft agar than MCF-10A Ha-ras, MCF-10A c-erbB-2, or MCF-10A TGF-alpha clones. However, neither MCF-10A TE nor MCF-10A HE cells were able to grow as tumors in vivo when they were injected into nude mice. These results suggest that c-Ha-ras, c-erbB-2, and TGF-alpha genes have an additive effect on the in vitro transformation of an immortalized human mammary epithelial cell line, but that additional genetic changes such as activation of other proto-oncogenes or inactivation of a tumor suppressor gene may be necessary to elicit a fully tumorigenic phenotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • Cell Division
  • Cell Transformation, Neoplastic / genetics*
  • Clone Cells
  • Epithelium / pathology
  • ErbB Receptors / physiology
  • Female
  • Genes, ras / physiology*
  • Humans
  • Mammary Neoplasms, Experimental / genetics
  • Mammary Neoplasms, Experimental / pathology
  • Mice
  • Mice, Inbred BALB C
  • Proto-Oncogene Proteins / physiology*
  • Receptor, ErbB-2
  • Transforming Growth Factor alpha / physiology*


  • Proto-Oncogene Proteins
  • Transforming Growth Factor alpha
  • ErbB Receptors
  • Receptor, ErbB-2