| First Author | Cookman CJ | Year | 2015 |
| Journal | Endocrinology | Volume | 156 |
| Issue | 7 | Pages | 2395-408 |
| PubMed ID | 25885794 | Mgi Jnum | J:224638 |
| Mgi Id | MGI:5688449 | Doi | 10.1210/en.2015-1141 |
| Citation | Cookman CJ, et al. (2015) Estrogen Receptor-beta Up-Regulates IGF1R Expression and Activity to Inhibit Apoptosis and Increase Growth of Medulloblastoma. Endocrinology 156(7):2395-408 |
| abstractText | Medulloblastoma (Med) is the most common malignant brain tumor in children. The role of ESR2 [estrogen receptor (ER)-beta] in promoting Med growth was comprehensively examined in three in vivo models and human cell lines. In a novel Med ERbeta-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 17beta-estradiol and the ERbeta 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 ERbeta and IGF1R receptor tyrosine kinase activity and independent of ERalpha and G protein-coupled estrogen receptor 1 (G protein coupled receptor 30). The presented results demonstrate that estrogen promotes Med growth through ERbeta-mediated increases in IGF1R expression and activity, which induce cytoprotective mechanisms that decrease apoptosis. |
