Membrane-associated binding sites for estrogen contribute to growth regulation of human breast cancer cells

• Published in: Oncogene Vol. 20; no. 39; pp. 5420 - 5430
• Main Authors: MARQUEZ, Diana C, PIETRAS, Richard J
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 06-09-2001; Nature Publishing Group
• Subjects: 17β-Estradiol; AKT protein; Animals; Antibodies; Antibodies - pharmacology; Binding Sites; Biological and medical sciences; Breast cancer; Breast Neoplasms - enzymology; Breast Neoplasms - pathology; Cancer; Cancer cells; Care and treatment; Cell Division - drug effects; Cell growth; Cell Membrane - metabolism; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Chemical properties; Contamination; Cytosol; Enzymes; Estradiol; Estradiol - metabolism; Estradiol - pharmacology; Estrogen Receptor alpha; Estrogen receptors; Estrogens; Female; Fundamental and applied biological sciences. Psychology; Growth; Hematology; Homogenization; Hormones; Humans; Intracellular signalling; Kinases; Kinetics; Ligands; MAP kinase; Membranes; Mice; Mice, Nude; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases - metabolism; Molecular and cellular biology; Monoclonal antibodies; Nucleotidase; Oncology; Phenols; Plasma; Plasma membranes; Protein kinase; Protein-Serine-Threonine Kinases; Proteins; Proto-Oncogene Proteins - metabolism; Proto-Oncogene Proteins c-akt; Receptors, Cell Surface - physiology; Receptors, Estrogen - antagonists & inhibitors; Receptors, Estrogen - chemistry; Receptors, Estrogen - physiology; Serum Albumin, Bovine - pharmacology; Tumor Cells, Cultured; Xenograft Model Antitumor Assays; Xenografts; Los Angeles California; United States > US; Human; Regulation(control); Association; Growth; Estrogen; Breast; Membrane; Regulation; Binding site; Mammary gland; Tumor cell
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1204729

Membrane-associated binding sites for estrogen may mediate rapid effects of estradiol-17beta that contribute to proliferation of human breast cancers. After controlled homogenization and fractionation of MCF-7 breast cancer cells, the bulk of specific estradiol binding is found in nuclear fractions. However, a significant portion of specific, high-affinity estradiol-17beta binding-sites are also enriched in plasma membranes. These estradiol binding-sites co-purify with 5'-nucleotidase, a plasma membrane-marker enzyme, and are free from major contamination by cytosol or nuclei. Electrophoresis of membrane fractions allowed detection of a primary 67-kDa protein and a secondary 46-kDa protein recognized by estradiol-17beta and by a monoclonal antibody directed to the ligand-binding domain of the nuclear form of estrogen receptor. Estrogen-induced growth of MCF-7 breast cancer cells in vitro was blocked by treatment with the antibody to estrogen receptor and correlated closely with acute hormonal activation of mitogen-activated protein kinase and Akt kinase signaling. Estrogen-promoted growth of human breast cancer xenografts in nude mice was also significantly reduced by treatment in vivo with the estrogen receptor antibody. Thus, membrane-associated forms of estrogen receptor may play a role in promoting intracellular signaling for hormone-mediated proliferation and survival of breast cancers and offer a new target for antitumor therapy.