Estrogen and growth factor receptor interactions in human breast and non-small cell lung cancer cells

Steroids. May-Jun 2005;70(5-7):372-81. doi: 10.1016/j.steroids.2005.02.017. Epub 2005 Mar 25.

Abstract

Extranuclear estrogen receptors may mediate rapid effects of estradiol that communicate with nuclear receptors and contribute to proliferation of human cancers bearing these signaling proteins. To assess these growth-promoting pathways, we undertook controlled homogenization and fractionation of NIH-H23 non-small cell lung cancer cells. As many breast tumors, NIH-H23 cells express estrogen receptors (ER), with the bulk of specific estradiol binding in nuclear fractions. However, as in breast cells, a significant portion of specific, high-affinity estradiol-17beta binding-sites are also enriched in plasma membranes of lung tumor cells. These estrogen binding-sites co-purify with plasma membrane-marker enzymes and are not significantly contaminated by cytosol or nuclei. On further purification of membrane caveolae from lung tumor cells, proteins recognized by monoclonal antibodies to nuclear ER-alpha and to ER-beta were identified in close association with EGF receptor in caveolae. In parallel studies, ER-alpha and ER-beta are also detected in nuclear and extranuclear sites in archival human breast and lung tumor samples and are noted to occur in clusters at the cell membrane by using confocal microscopy to visualize fluorescent-labeled monoclonal antibodies to ER-alpha. Data on site-directed mutagenesis of cysteine-447 in ER-alpha suggest that association of ER forms with membrane sites may depend on acylation of cysteine by palmitate. Estrogen-induced growth of MCF-7 breast cancer and NIH-H23 lung cancer cells in vitro correlated closely with acute hormonal activation of mitogen-activated protein kinase signaling and was significantly reduced by treatment with Faslodex, a pure anti-estrogen. Further, combination of Faslodex with selected growth factor receptor inhibitors elicited a more pronounced inhibiton of tumor cell growth. Thus, extranuclear forms of ER play a role in promoting downstream signaling for hormone-mediated proliferation and survival of breast, as well as lung, cancers and offer a new target for anti-tumor therapy.

Publication types

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

MeSH terms

  • Active Transport, Cell Nucleus
  • Antineoplastic Agents, Hormonal / pharmacology
  • Aromatase / metabolism
  • Breast Neoplasms / metabolism*
  • Carcinoma, Non-Small-Cell Lung / metabolism*
  • Cell Line, Tumor
  • Cell Membrane / metabolism
  • Cell Nucleus / metabolism
  • Cell Proliferation
  • Cell Survival
  • Cytosol / metabolism
  • Estradiol / analogs & derivatives
  • Estradiol / metabolism
  • Estradiol / pharmacology
  • Estrogens / metabolism*
  • Fulvestrant
  • Genetic Vectors
  • Growth Substances / metabolism*
  • Humans
  • Lung Neoplasms / metabolism*
  • Microscopy, Fluorescence
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Mutagenesis, Site-Directed
  • Phosphorylation
  • Protein Binding
  • Protein-Tyrosine Kinases / metabolism
  • Receptors, Estrogen / metabolism
  • Signal Transduction
  • Subcellular Fractions / metabolism
  • Transfection
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Antineoplastic Agents, Hormonal
  • Estrogens
  • Growth Substances
  • Receptors, Estrogen
  • Vascular Endothelial Growth Factor A
  • Fulvestrant
  • Estradiol
  • Aromatase
  • Protein-Tyrosine Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3