title: Estrogen Receptor-β Up-Regulates IGF1R Expression and Activity to Inhibit Apoptosis and Increase Growth of Medulloblastoma.
abstract: Medulloblastoma (Med) is the most common malignant brain tumor in children. The role of ESR2 [estrogen receptor (ER)-β] in promoting Med growth was comprehensively examined in three in vivo models and human cell lines. In a novel Med ERβ-null knockout model developed by crossing Esr2(-/-) mice with cerebellar granule cell precursor specific Ptch1 conditional knockout mice, the tumor growth rate was significantly decreased in males and females. The absence of Esr2 resulted in increased apoptosis, decreased B-cell lymphoma 2 (BCL2), and IGF-1 receptor (IGF1R) expression, and decreased levels of active MAPKs (ERK1/2) and protein kinase B (AKT). Treatment of Med in Ptch1(+/-) Trp53(-/-) mice with the antiestrogen chemotherapeutic drug Faslodex significantly increased symptom-free survival, which was associated with increased apoptosis and decreased BCL2 and IGF1R expression and signaling. Similar effects were also observed in nude mice bearing D283Med xenografts. In vitro studies in human D283Med cells metabolically stressed by glutamine withdrawal found that 17β-estradiol and the ERβ selective agonist 2,3-bis(4-hydroxyphenyl)-propionitrile dose dependently protected Med cells from caspase-3-dependent cell death. Those effects were associated with increased phosphorylation of IGF1R, long-term increases in ERK1/2 and AKT signaling, and increased expression of IGF-1, IGF1R, and BCL2. Results of pharmacological experiments revealed that the cytoprotective actions of estradiol were dependent on ERβ and IGF1R receptor tyrosine kinase activity and independent of ERα and G protein-coupled estrogen receptor 1 (G protein coupled receptor 30). The presented results demonstrate that estrogen promotes Med growth through ERβ-mediated increases in IGF1R expression and activity, which induce cytoprotective mechanisms that decrease apoptosis.
authors.affiliation: Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0575.
authors.forename: Clifford J
authors.initials: CJ
authors.lastname: Cookman
authors.affiliation: Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0575.
authors.forename: Scott M
authors.initials: SM
authors.lastname: Belcher
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D004958:Estradiol / Q000494:pharmacology; D047629:Estrogen Receptor beta / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008297:Male; D008527:Medulloblastoma / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D017526:Receptor, IGF Type 1 / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D047629:Estrogen Receptor beta; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D019253:Proto-Oncogene Proteins c-bcl-2; C000606240:Ptch1 protein, mouse; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D016159:Tumor Suppressor Protein p53; C052617:Bcl2 protein, mouse; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1; D053148:Caspase 3