Article

Impact of estrogen receptor beta on gene networks regulated by estrogen receptor alpha in breast cancer cells

Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois, United States
Endocrinology (Impact Factor: 4.64). 11/2006; 147(10):4831-42. DOI: 10.1210/en.2006-0563
Source: PubMed

ABSTRACT Two subtypes of the estrogen receptor (ER), ERalpha and ERbeta, mediate the actions of estrogens, and although 70% of human breast cancers express ERbeta along with ERalpha, little is known about the possible comodulatory effects of these two ERs. To investigate this, we have used adenoviral gene delivery to produce human breast cancer (MCF-7) cells expressing different levels of ERbeta, along with their endogenous ERalpha, and have examined the effects of ERbeta and receptor occupancy, using ER subtype selective ligands, on genome-wide gene expression by microarray and pathway network analysis. ERbeta had diverse effects on gene expression, enhancing or counteracting ERalpha regulation for distinct subsets of estrogen target genes. Strikingly, ERbeta in the absence of estradiol (E2), elicited the stimulation or suppression of many genes that were normally only regulated by ERalpha with E2. In addition, ERbeta plus E2 elicited the expression of a unique group of genes that were not regulated by ERalpha plus E2 alone. The expression of genes in many functional categories were modulated by ERbeta, with the greatest numbers associated with transcription factors and signal transduction pathways. Regulation of multiple components in the TGFbeta and semaphorin pathways, and of genes controlling cell cycle progression and apoptosis, may contribute to the suppression of cell proliferation observed with ERbeta. Our observations suggest that the relative levels of ERbeta and ERalpha in breast cancers are likely to impact cell proliferation and the activities of diverse signaling pathways and their response to ER ligands and endocrine therapies.

0 Followers
 · 
115 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Phytoestrogens are used as 'natural' alternatives to HRT and, although epidemiological evidence implies that diets rich in phytoestrogens reduce the incidence of breast cancer, their weak oestrogenicity is also known to stimulate growth in experimental models of breast cancer. This review addresses the question as to how phytoestrogens may protect against breast cancer through their ability to bind preferentially to oestrogen receptor beta, inhibit enzymes that convert circulating steroid precursors into oestradiol and inhibit cell signalling pathways of growth factors.
    The Journal of Steroid Biochemistry and Molecular Biology 03/2008; 108(3-5):186-95. DOI:10.1016/j.jsbmb.2007.09.003 · 4.05 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Estrogens play an important role in breast cancer (BC) development and progression; when the two isoforms of the estrogen receptor (ERα and ERβ) are co-expressed each of them mediate specific effects of these hormones in BC cells. ERβ has been suggested to exert an antagonist role toward the oncogenic activities of ERα, and for this reason it is considered an oncosuppressor. As clinical evidence regarding a prognostic role for this receptor subtype in hormone-responsive BC is still limited and conflicting, more knowledge is required on the biological functions of ERβ in cancer cells. We have previously described the ERβ and ERα interactomes from BC cells, identifying specific and distinct patterns of protein interactions for the two receptors. In particular, we identified factors involved in mRNA splicing and maturation as important components of both ERα and ERβ pathways. Guided by these findings, here we performed RNA sequencing to investigate in depth the differences in the early transcriptional events and RNA splicing patterns induced by estradiol in cells expressing ERα alone or ERα and ERβ. Results Exon skipping was the most abundant splicing event in the post-transcriptional regulation by estradiol. We identified several splicing events induced by ERα alone and by ERα + ERβ, demonstrating for the first time that ERβ significantly affects estrogen-induced splicing in BC cells, as revealed by modification of a subset of ERα-dependent splicing by ERβ, as well as by the presence of splicing isoforms only in ERβ + cells. In particular, we observed that ERβ + BC cell lines exhibited around 2-fold more splicing events than the ERβ- cells. Interestingly, we identified putative direct targets of ERβ-mediated alternative splicing by correlating the genomic locations of ERβ and ERα binding sites with estradiol-induced differential splicing in the corresponding genes. Conclusions Taken together, these results demonstrate that ERβ significantly affects estrogen-induced early transcription and mRNA splicing in hormone-responsive BC cells, providing novel information on the biological role of ERβ in these tumors. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1541-1) contains supplementary material, which is available to authorized users.
    BMC Genomics 05/2015; 16(1). DOI:10.1186/s12864-015-1541-1 · 4.04 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To assess whether and how ERβ1 and/or ERβ2 expression status could predict response of early stage ERα-positive breast carcinoma to adjuvant endocrine therapy (AET). ERβ1 and ERβ2 expression were determined using immunohistochemistry. ERβ1- and ERβ2-positivity were derived from receiver operating characteristic analysis and the median percentage of immunostained tumor cells, respectively. Patients with recurrent disease were grouped according to whether they relapsed within 4 years or after 4 years from surgery. The predictive significance of ERβ1 and ERβ2 was determined using Kaplan-Meier survival analysis and Cox proportional hazards regression analysis. ERβ1-positivity in the first-4-year relapse patient group was lower and ERβ2-positivity in the post-4-year relapse group was higher compared to no-relapse group. ERβ1-positivity was associated with lower tumor size and longer first-4-year disease-free survival, while ERβ2-positivity was associated with shorter post-4-year disease-free survival. Cox multivariate analysis including ERβ1, ERβ2 and established clinico-pathological variables showed that ERβ1-positivity was an independent predictor of lower first-4-year risk of relapse. Low ERβ1 expression and high ERβ2 expression are markers for identification of AET-treated ERα-positive breast carcinoma patients at risk of early and late relapse, respectively. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
    Cancer Letters 12/2014; 358(1). DOI:10.1016/j.canlet.2014.12.022 · 5.02 Impact Factor

Preview

Download
1 Download

Similar Publications