Biomedical Sciences ETDs

Author

Sara Alcon

Publication Date

5-1-2014

Abstract

Proliferation and migration are critical steps within normal mammary development and breast cancer progression. While 17β-estradiol (E2) stimulates proliferation in normal and breast cancer cells through estrogen receptor-α (ERα) and G Protein-Coupled Estrogen Receptor-1 (GPER) [1-3], GPER regulation of E2-dependent migration has not been fully examined. GPER upregulates pathways necessary for increased migration, including vimentin, matrix metalloproteinase-9, and mitogen activated protein kinase (MAPK) signaling [1, 4-6]. GPER may also increase phospho-focal adhesion kinase (p-FAK) through Src activation [7, 8]. As a tumor develops, it produces transforming growth factor-β (TGF-β) to activate normal fibroblasts in the stroma, transforming them into cancer-associated fibroblasts (CAFs) and resulting in increased metastasis. As metastasis is the primary cause of cancer-related death, it is critical to examine how CAF activation is regulated [9-11]. GPER upregulates connective tissue growth factor, an enhancer of TGF-β-induced fibroblast activation, and is correlated with increased breast cancer metastasis [12-14], suggesting a role for GPER in fibroblast activation and metastasis. In this study, GPER activation increased MCF10A breast epithelial cell migration. Concomitant with GPER-dependent migration, increased expression of proteins supporting collective migration was observed, including vimentin, p-FAK, E-cadherin, and β-catenin, without increased proliferation. GPER inhibited PyMT breast cancer cell individual migration. Additionally, GPER increased normal fibroblast activation and proliferation in an EGFR-ERK-dependent manner but inhibited migration in vitro. In vivo, the absence of GPER expression in fibroblasts increased tumor metastasis and metastatic lesions size but did not affect collagen production. This is the first study to demonstrate a role for GPER in migration of normal breast epithelial cells, activation of normal fibroblasts, and the inhibition of tumor metastasis. Separately, the role of GPER in the classical uterine responses to estrogen activity, proliferation and water imbibition, traditionally attributed to ERα activation, was examined. G-1, a GPER-selective ligand, stimulated lumenal epithelial cell proliferation but not imbibition. AB-1, an ERα- and ERβ-selective ligand that activates genomic responses but not rapid signaling, stimulated proliferation and imbibition. However, rapid signaling is required for complete imbibition as AB-1 only induced ~60% of the E2-induced imbibition.

Keywords

Breast Cancer, Fibroblasts, GPER

Sponsors

National Institute of Health

Document Type

Dissertation

Language

English

Degree Name

Biomedical Sciences

Level of Degree

Doctoral

Department Name

Biomedical Sciences Graduate Program

First Advisor

Hathaway, Helen

First Committee Member (Chair)

Prossnitz, Eric

Second Committee Member

Hartley, Rebecca

Third Committee Member

Hudson, Laurie

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