Identification of estrogen receptor ligands leading to activation of non-genomic signaling pathways while exhibiting only weak transcriptional activity.
Estrogen receptors (ERs) stimulate genomic effects by acting as nuclear transcription factors as well as non-genomic effects by activating distinct cytoplasmic protein kinase cascades. Non-genomic effects have been implicated in numerous cellular processes, such as proliferation, differentiation, apoptosis and vasorelaxation. To exploit non-genomic effects mediated by ERalpha for novel hormone replacement regimens, we screened a focused library of steroid receptor ligands to identify compounds exhibiting properties different from estradiol, i.e. substances that selectively stimulate non-genomic signal transduction pathways while exhibiting low genomic activities. Treatment of breast cancer cells and osteosarcoma cells with estradiol, estren, substance A and substance B led to non-genomic activation of Akt (protein kinase B) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling cascades mediated by Src (Rous Sarcoma Virus, non-receptor tyrosine kinase) and phosphatidylinositol-3-kinase (PI3K) stimulation. Such compounds leading to prominent Akt/ERK activation but exhibiting only weak genomic properties were applied in vasorelaxation assays, modeling physiological non-genomic ER responses. As expected from PI3K and Src activation data, substances were as effective as estradiol in mediating vasorelaxation. We assume that these pathway-selective estrogen receptor ligands may serve as potent lead structures for novel hormone replacement strategies exhibiting lesser side effects than the existing treatment paradigms.
Wessler
Silja
S
Paul-Ehrlich-Institute, Paul-Ehrlich Strasse 51-59, D-63225 Langen, Germany. wessi@pei.de
Otto
Christiane
C
Wilck
Nicola
N
Stangl
Verena
V
Fritzemeier
Karl-Heinrich
KH
D000818:Animals; D001011:Aorta / Q000187:drug effects; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D058534:Class I Phosphatidylinositol 3-Kinases; D004958:Estradiol / Q000494:pharmacology; D006801:Humans; D047468:Immunoprecipitation; D008024:Ligands; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D012516:Osteosarcoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011960:Receptors, Estrogen / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D014664:Vasodilation / Q000187:drug effects; D019061:src-Family Kinases / Q000378:metabolism
D008024:Ligands; D011960:Receptors, Estrogen; D004958:Estradiol; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; D019061:src-Family Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3