Mechanism of 17-β-Estradiol-induced Erk1/2 Activation in Breast Cancer Cells

Activation of mitogen-activated protein kinase (Erk/MAPK) is a critical signal transduction event for estrogen (E2)-mediated cell proliferation. Recent studies from our group and others have shown that persistent activation of Erk plays a major role in cell migration and tumor progression. The signaling mechanism(s) responsible for persistent Erk activation are not fully characterized, however. In this study, we have shown that E2 induces a slow but persistent activation of Erk in MCF-7 breast carcinoma cells. The E2-induced Erk activation is dependent on new protein synthesis, suggesting that E2-induced growth factors play a major role in Erk activation. When MCF-7 cells were treated with E2 in the presence of an anti-HER-2 monoclonal antibody (herceptin), 60–70% of E2-induced Erk activation is blocked. In addition, when untreated MCF-7 cells were exposed to conditioned medium from E2-treated cells, Erk activity was significantly enhanced. Furthermore Erk activity was blocked by an antibody against HER-2 or by heregulin (HRG) depletion from the conditioned medium through immunoprecipitation. In contrast, epidermal growth factor receptor (Ab528) antibody only blocked 10–20% of E2-induced Erk activation, suggesting that E2-induced Erk activation is predominantly mediated through the secretion of HRG and activation of HER-2 by an autoctine/paracrine mechanism. Inhibition of PKC-δ-mediated signaling by a dominant negative mutant or the relatively specific PKC-δ inhibitor rottlerin blocked most of the E2-induced Erk activation but had no effect on TGFα-induced Erk activation. By contrast inhibition of Ras, by inhibition of farnesyl transferase (Ftase-1) or dominant negative (N17)-Ras, significantly inhibited both E2- and TGFα-induced Erk activation. This evaluation of downstream signaling revealed that E2-induced Erk activation is mediated by a HRG/HER-2/PKC-δ/Ras pathway that could be crucial for E2-dependent growth-promoting effects in early stages of tumor progression.

[1]  R. Mattingly,et al.  Low concentrations of inorganic mercury inhibit Ras activation during T cell receptor-mediated signal transduction. , 2001, Toxicology and applied pharmacology.

[2]  D. Miles.  Update on HER-2 as a target for cancer therapy: Herceptin in the clinical setting , 2001, Breast cancer research : BCR.

[3]  K. Lackey,et al.  The characterization of novel, dual ErbB-2/EGFR, tyrosine kinase inhibitors: potential therapy for cancer. , 2001, Cancer research.

[4]  N. Rosen,et al.  The tyrosine kinase inhibitor ZD1839 ("Iressa") inhibits HER2-driven signaling and suppresses the growth of HER2-overexpressing tumor cells. , 2001, Cancer research.

[5]  E. Levin,et al.  Rapid actions of plasma membrane estrogen receptors , 2001, Trends in Endocrinology & Metabolism.

[6]  C. Lindley,et al.  Pharmacology and therapeutic use of trastuzumab in breast cancer. , 2000, American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists.

[7]  A. Lenferink,et al.  Inhibition of HER2/neu (erbB-2) and mitogen-activated protein kinases enhances tamoxifen action against HER2-overexpressing, tamoxifen-resistant breast cancer cells. , 2000, Cancer research.

[8]  G. King,et al.  Identification of PKC-isoform-specific biological actions using pharmacological approaches. , 2000, Trends in pharmacological sciences.

[9]  Zhimin Lu,et al.  Antagonistic Effects of Protein Kinase C α and δ on Both Transformation and Phospholipase D Activity Mediated by the Epidermal Growth Factor Receptor , 1999, Molecular and Cellular Biology.

[10]  K. Reddy,et al.  Mitogen‐activated protein kinase (MAPK) regulates the expression of progelatinase B (MMP‐9) in breast epithelial cells , 1999, International journal of cancer.

[11]  I. Weinstein,et al.  Response Element Serum Fos Kinase C in Activation of the C- Novel Roles of Specific Isoforms of Protein , 1999 .

[12]  M. Pagano,et al.  Activation of Protein Kinase C Triggers Its Ubiquitination and Degradation , 1998, Molecular and Cellular Biology.

[13]  S. Kato,et al.  Rapid activation of MAP kinase by estrogen in the bone cell line. , 1997, Biochemical and biophysical research communications.

[14]  N. Normanno,et al.  EGF-Related Peptides in the Pathophysiology of the Mammary Gland , 1997, Journal of Mammary Gland Biology and Neoplasia.

[15]  A. Newton,et al.  Regulation of protein kinase C. , 1997, Current opinion in cell biology.

[16]  J. Bos,et al.  Minimal Ras-binding domain of Raf1 can be used as an activation-specific probe for Ras , 1997, Oncogene.

[17]  D. Shalloway,et al.  Cell cycle-dependent activation of Ras , 1996, Current Biology.

[18]  N. Weigel.  Steroid hormone receptors and their regulation by phosphorylation. , 1996, The Biochemical journal.

[19]  Shigeo Ohno,et al.  Protein Kinase C δ Activates the MEK-ERK Pathway in a Manner Independent of Ras and Dependent on Raf* , 1996, The Journal of Biological Chemistry.

[20]  I. Macara,et al.  Phosphorylation-dependent activation of the Ras-GRF/CDC25Mm exchange factor by muscarinic receptors and G-protein βγ subunits , 1996, Nature.

[21]  R. Lupu,et al.  Involvement of Heregulin-β2 in the Acquisition of the Hormone-independent Phenotype of Breast Cancer Cells , 1996 .

[22]  A. Saltiel,et al.  Role of Mitogen-activated Protein Kinase Kinase in Regulation of the Epidermal Growth Factor Receptor by Protein Kinase C* , 1996, The Journal of Biological Chemistry.

[23]  J. Lord,et al.  The Polyether Bistratene A Activates Protein Kinase C–δ and Induces Growth Arrest in HL60 Cells , 1996 .

[24]  N. Hynes,et al.  Epidermal Growth Factor-related Peptides Activate Distinct Subsets of ErbB Receptors and Differ in Their Biological Activities (*) , 1996, The Journal of Biological Chemistry.

[25]  P. Bontempo,et al.  Tyrosine kinase/p21ras/MAP‐kinase pathway activation by estradiol‐receptor complex in MCF‐7 cells. , 1996, The EMBO journal.

[26]  E. Milgrom,et al.  Intracellular traffic of steroid hormone receptors , 1996, The Journal of Steroid Biochemistry and Molecular Biology.

[27]  K. Umesono,et al.  The nuclear receptor superfamily: The second decade , 1995, Cell.

[28]  Miguel Beato,et al.  Steroid hormone receptors: Many Actors in search of a plot , 1995, Cell.

[29]  Daniel Metzger,et al.  Activation of the Estrogen Receptor Through Phosphorylation by Mitogen-Activated Protein Kinase , 1995, Science.

[30]  R. Dickson,et al.  Growth factors in breast cancer. , 1995, Endocrine reviews.

[31]  A. Ullrich,et al.  Heregulin‐dependent regulation of HER2/neu oncogenic signaling by heterodimerization with HER3. , 1995, The EMBO journal.

[32]  E. Peles,et al.  Protein tyrosine kinase PYK2 involved in Ca2+-induced regulation of ion channel and MAP kinase functions , 1995, Nature.

[33]  T. Pawson,et al.  The PTB domain: a new protein module implicated in signal transduction. , 1995, Trends in biochemical sciences.

[34]  M. Sliwkowski,et al.  HER-2 tyrosine kinase pathway targets estrogen receptor and promotes hormone-independent growth in human breast cancer cells. , 1995, Oncogene.

[35]  F. Kern,et al.  MCF-7 breast cancer cells overexpressing transfectedc-erbB-2 have anin vitro growth advantage in estrogen-depleted conditions and reduced estrogen-dependence and tamoxifen-sensitivityin vivo , 1995, Breast Cancer Research and Treatment.

[36]  A. Bilancio,et al.  The role of estradiol receptor in the proliferative activity of vanadate on MCF-7 cells. , 1995, Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research.

[37]  N. Hynes,et al.  The biology of erbB-2/neu/HER-2 and its role in cancer. , 1994, Biochimica et biophysica acta.

[38]  S. Hilsenbeck,et al.  Inhibition of estrogen-induced breast cancer cell proliferation by reduction in autocrine transforming growth factor alpha expression. , 1994, Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research.

[39]  S. Stabel,et al.  Signalling from TPA to MAP kinase requires protein kinase C, raf and MEK: reconstitution of the signalling pathway in vitro. , 1994, Oncogene.

[40]  C. Heldin,et al.  Activation of p70/p85 S6 kinase by a pathway independent of p21fi ras , 1994, Nature.

[41]  C. Leslie,et al.  Protein kinase C-dependent and -independent pathways of mitogen-activated protein kinase activation in macrophages by stimuli that activate phospholipase A2. , 1994, The Journal of biological chemistry.

[42]  J. Frost,et al.  A requirement for extracellular signal-regulated kinase (ERK) function in the activation of AP-1 by Ha-Ras, phorbol 12-myristate 13-acetate, and serum. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[43]  D. Taverna,et al.  ErbB‐2 expression in estrogen‐receptor‐positive breast‐tumor cells is regulated by growth‐modulatory reagents , 1994, International journal of cancer.

[44]  J. Pouysségur,et al.  Mitogen-activated protein kinases p42mapk and p44mapk are required for fibroblast proliferation. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[45]  Walter Kolch,et al.  Protein kinase Cα activates RAF-1 by direct phosphorylation , 1993, Nature.

[46]  R. Davis,et al.  The mitogen-activated protein kinase signal transduction pathway. , 1993, The Journal of biological chemistry.

[47]  J. Blenis,et al.  Signal transduction via the MAP kinases: proceed at your own RSK. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[48]  G. Martiny-Baron,et al.  Selective inhibition of protein kinase C isozymes by the indolocarbazole Gö 6976. , 1993, The Journal of biological chemistry.

[49]  E. Nishida,et al.  The MAP kinase cascade is essential for diverse signal transduction pathways. , 1993, Trends in biochemical sciences.

[50]  M. Cobb,et al.  Regulation and properties of extracellular signal-regulated protein kinases 1 and 2 in vitro. , 1993, The Journal of biological chemistry.

[51]  E. Krebs,et al.  Human T-cell mitogen-activated protein kinase kinases are related to yeast signal transduction kinases. , 1992, The Journal of biological chemistry.

[52]  Y. Nishizuka.  Intracellular signaling by hydrolysis of phospholipids and activation of protein kinase C. , 1992, Science.

[53]  P. Cohen,et al.  Activation of the MAP kinase pathway by the protein kinase raf , 1992, Cell.

[54]  C. Osborne,et al.  Inhibition of breast cancer cell growth in vitro by a tyrosine kinase inhibitor. , 1992, Cancer research.

[55]  J. Bos,et al.  Involvement of p21ras in activation of extracellular signal-regulated kinase 2 , 1992, Nature.

[56]  J. Blenis,et al.  ras mediates nerve growth factor receptor modulation of three signal-transducing protein kinases: MAP kinase, Raf-1, and RSK , 1992, Cell.

[57]  Sheila M. Thomas,et al.  Ras is essential for nerve growth factor- and phorbol ester-induced tyrosine phosphorylation of MAP kinases , 1992, Cell.

[58]  P. Cohen,et al.  Dissection of the protein kinase cascade by which nerve growth factor activates MAP kinases , 1991, Nature.

[59]  A. Harris,et al.  c-erbB-2 protein overexpression in breast cancer is a risk factor in patients with involved and uninvolved lymph nodes. , 1991, British Journal of Cancer.

[60]  B. Burg,et al.  Direct effects of estrogen on c-fos and c-myc protooncogene expression and cellular proliferation in human breast cancer cells , 1989, Molecular and Cellular Endocrinology.

[61]  S. Singletary,et al.  Elevated protein kinase C expression in human breast tumor biopsies relative to normal breast tissue. , 1989, Cancer research.

[62]  M. Kraus,et al.  Overexpression of erbB-2 or EGF receptor proteins present in early stage mammary carcinoma is detected simultaneously in matched primary tumors and regional metastases. , 1989, Oncogene.

[63]  C. Osborne,et al.  Blockade of the epidermal growth factor receptor inhibits transforming growth factor alpha-induced but not estrogen-induced growth of hormone-dependent human breast cancer. , 1988, Molecular endocrinology.

[64]  J. Maller,et al.  Insulin-stimulated MAP-2 kinase phosphorylates and activates ribosomal protein S6 kinase II , 1988, Nature.

[65]  R. Shiu,et al.  Stimulation of c-myc oncogene expression associated with estrogen-induced proliferation of human breast cancer cells. , 1987, Cancer research.

[66]  H. Rochefort,et al.  Antiestrogens inhibit the mitogenic effect of growth factors on breast cancer cells in the total absence of estrogens. , 1987, Biochemical and biophysical research communications.

[67]  R. Dickson,et al.  Estrogenic regulation of growth and polypeptide growth factor secretion in human breast carcinoma. , 1987, Endocrine reviews.

[68]  D. Fabbro,et al.  Epidermal growth factor binding and protein kinase C activities in human breast cancer cell lines: possible quantitative relationship. , 1986, Cancer research.

[69]  J. Mendelsohn,et al.  Monoclonal anti-epidermal growth factor receptor antibodies which are inhibitors of epidermal growth factor binding and antagonists of epidermal growth factor binding and antagonists of epidermal growth factor-stimulated tyrosine protein kinase activity. , 1984, The Journal of biological chemistry.

[70]  P. Seeburg,et al.  Human epidermal growth factor receptor cDNA sequence and aberrant expression of the amplified gene in A431 epidermoid carcinoma cells , 1984, Nature.

[71]  J. Mendelsohn,et al.  Growth stimulation of A431 cells by epidermal growth factor: identification of high-affinity receptors for epidermal growth factor by an anti-receptor monoclonal antibody. , 1983, Proceedings of the National Academy of Sciences of the United States of America.

[72]  S. Martino,et al.  HER-2 expression and response to tamoxifen in estrogen receptor-positive breast cancer: a Southwest Oncology Group Study. , 1998, Clinical cancer research : an official journal of the American Association for Cancer Research.

[73]  W. Gullick,et al.  Prevalence of aberrant expression of the epidermal growth factor receptor in human cancers. , 1991, British medical bulletin.

[74]  Anita B. Roberts,et al.  Autocrine growth factors and cancer , 1985, Nature.