AUTHOR=Girgert Rainer , Emons Günter , Gründker Carsten 

TITLE=Estrogen Signaling in ERα-Negative Breast Cancer: ERβ and GPER

JOURNAL=Frontiers in Endocrinology

VOLUME=Volume 9 - 2018

YEAR=2019

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2018.00781

DOI=10.3389/fendo.2018.00781

ISSN=1664-2392

ABSTRACT=Estrogen receptors are important regulators of the growth of breast tumors. Three different receptors for estrogens have been identified in breast tumors, two nuclear receptors, ERα and ERβ and a G-protein coupled estrogen receptor (GPER) that initiates the non-genomic effects of estrogens in the cytosol. The treatment of breast cancer with anti-estrogens depends on the presence of ERα. About 40% of all breast cancers, however, do not express ERα. One subgroup of these tumors overexpress Her-2, another important group is designated as triple-negative breast cancer, as they neither express ERα, nor progesterone receptors, nor do they overexpress Her-2. This review addresses the signaling of ERβ and GPER in ERα-negative breast tumors. In addition to the well-established EGF-receptor transactivation pathways of GPER more recent findings of GPER-dependent activation of FOXO3a, the Hippo-pathway and HOTAIR-activation are summarized.