%0 Journal Article
%T Estrogen Regulates MAPK-Related Genes through Genomic and Nongenomic Interactions between IGF-I Receptor Tyrosine Kinase and Estrogen Receptor-Alpha Signaling Pathways in Human Uterine Leiomyoma Cells
%A Linda Yu
%A Alicia B. Moore
%A Lysandra Castro
%A Xiaohua Gao
%A Hoang-Long C. Huynh
%A Michelle Klippel
%A Norris D. Flagler
%A Yi Lu
%A Grace E. Kissling
%A Darlene Dixon
%J Journal of Signal Transduction
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/204236
%X Estrogen and growth factors play a major role in uterine leiomyoma (UtLM) growth possibly through interactions of receptor tyrosine kinases (RTKs) and estrogen receptor-alpha (ER ) signaling. We determined the genomic and nongenomic effects of 17 -estradiol (E2) on IGF-IR/MAPKp44/42 signaling and gene expression in human UtLM cells with intact or silenced IGF-IR. Analysis by RT2 Profiler PCR-array showed genes involved in IGF-IR/MAPK signaling were upregulated in UtLM cells by E2 including cyclin D kinases, MAPKs, and MAPK kinases; RTK signaling mediator, GRB2; transcriptional factors ELK1 and E2F1; CCNB2 involved in cell cycle progression, proliferation, and survival; and COL1A1 associated with collagen synthesis. Silencing (si)IGF-IR attenuated the above effects and resulted in upregulation of different genes, such as transcriptional factor ETS2; the tyrosine kinase receptor, EGFR; and DLK1 involved in fibrosis. E2 rapidly activated IGF-IR/MAPKp44/42 signaling nongenomically and induced phosphorylation of ER at ser118 in cells with a functional IGF-IR versus those without. E2 also upregulated IGF-I gene and protein expression through a prolonged genomic event. These results suggest a pivotal role of IGF-IR and possibly other RTKs in mediating genomic and nongenomic hormone receptor interactions and signaling in fibroids and provide novel genes and targets for future intervention and prevention strategies. 1. Introduction Although the exact etiology of uterine leiomyomas (fibroids) is unknown, the fact that they develop during the reproductive years and regress after menopause indicates that they are hormonally regulated [1¨C3]. The important role of estrogen in the promotion of uterine leiomyoma growth has been well supported through clinical and biological studies [4¨C6]. However, the overexpression of growth factors and their receptors, such as the type I insulin-like growth factor (IGF-I) and IGF-I receptor (IGF-IR), shows that sex steroids are not the only modulators of leiomyoma cell proliferation and exuberant extracellular matrix formation observed in many fibroids [2, 7¨C9]. Studies have revealed that IGF-I expression is most abundant in leiomyomas during the proliferative phase of the menstrual cycle [10, 11]. The expression of IGF-I mRNA increases in leiomyomas, and estrogen receptor alpha (ER ) mRNA is positively correlated with IGF-I mRNA levels, which implies as we and others have shown that estrogen upregulates the gene encoding IGF-I through ER in leiomyoma tissue and cells [10¨C13]. The accumulated data from extensive studies of breast
%U http://www.hindawi.com/journals/jst/2012/204236/