RAS transformation causes sustained activation of epidermal growth factor receptor and elevation of mitogen-activated protein kinase in human mammary epithelial cells

Int J Cancer. 2000 Oct 1;88(1):44-52. doi: 10.1002/1097-0215(20001001)88:1<44::aid-ijc7>3.0.co;2-8.

Abstract

Activation of the ras oncogene is an important step in carcinogenesis. Human MCF-10A mammary epithelial cells were transformed with a point-mutated form of the Ha-ras oncogene. Epidermal growth factor receptor (EGFR) phosphorylation levels were chronically elevated after EGF induction and the EGFR ligand-driven internalization rate was slower in Ha-ras transformed MCF-10A cells. Additionally, basal levels of p42/44 mitogen-activated protein kinase (MAPK) expression and enzyme activity were significantly higher in Ha-ras transformed cells, localized predominantly in the nucleus. The anti-EGFR monoclonal antibody (MAb) 225 and the EGFR tyrosine kinase inhibitor PD153035 blocked anchorage-independent growth of Ha-ras transformed cells in soft agar and were more effective when used in combination. The MEK inhibitor PD98059 and anti-erbB-2 MAb L26 also suppressed colony formation of Ha-ras transformed cells in soft agar. Therefore, Ha-ras transformation leads to an augmentation in signaling through the EGFR as a result of an increase in ligand-dependent phosphorylation, a decrease in its internalization and an up-regulation in basal p44/42 MAPK levels. These effects may contribute to uncontrolled growth of Ha-ras-transformed human mammary epithelial cells.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / pharmacology
  • Antibody Specificity
  • Breast / enzymology
  • Breast / metabolism*
  • Breast / pathology
  • Cell Line, Transformed
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / metabolism*
  • Cells, Cultured
  • Enzyme Activation
  • Enzyme Inhibitors / pharmacology
  • Epidermal Growth Factor / metabolism
  • Epidermal Growth Factor / pharmacokinetics
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism
  • ErbB Receptors / physiology*
  • Female
  • Gene Expression Regulation
  • Genes, ras / genetics
  • Genes, ras / physiology*
  • Growth Inhibitors / pharmacology
  • Humans
  • MAP Kinase Signaling System / physiology
  • Mitogen-Activated Protein Kinase 1 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 1 / biosynthesis
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinases / biosynthesis*
  • Mitogen-Activated Protein Kinases / metabolism
  • Phosphorylation
  • Point Mutation
  • Proto-Oncogene Proteins c-raf / genetics
  • Proto-Oncogene Proteins c-raf / metabolism
  • Proto-Oncogene Proteins p21(ras) / genetics
  • Proto-Oncogene Proteins p21(ras) / metabolism
  • Subcellular Fractions / enzymology
  • Substrate Specificity
  • Transfection

Substances

  • Antibodies, Monoclonal
  • Enzyme Inhibitors
  • Growth Inhibitors
  • Epidermal Growth Factor
  • ErbB Receptors
  • Proto-Oncogene Proteins c-raf
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • HRAS protein, human
  • Proto-Oncogene Proteins p21(ras)