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Differences in the Transcriptional Response to Fulvestrant and Estrogen Deprivation in ER-Positive Breast Cancer

ABSTRACT: Aromatase inhibitors are first-line postmenopausal agents for estrogen receptor alpha (ERa)-positive breast cancer. However, there is considerable response heterogeneity and women frequently relapse. Estrogen deprivation does not completely arrest ERa activity, and transactivation of the unliganded receptor may continue through cross-talk with growth factor pathways. In contrast with aromatase inhibitors, the selective ER downregulator fulvestrant also abrogates ligand-independent ERa activity. The benefit of fulvestrant as an alternative, combination, or sequential therapy to aromatase inhibitor has been reported, but molecular mechanisms underpinning its relative efficacy remain unclear and biomarkers for patient selection are lacking. This study demonstrates, for the first time, that the overall transcriptional response to fulvestrant is of greater magnitude than estrogen deprivation, consistent with its clinical efficacy and more complete blockade of estrogenic signaling. Using a robust integrative approach, we identify a subset of genes differentially affected by fulvestrant that comprises distinct biologic networks, correlates with antiproliferative response, and has potential utility as predictive biomarkers for fulvestrant.

ORGANISM(S): Homo sapiens

PROVIDER: GSE71791 | GEO | 2015/08/07

SECONDARY ACCESSION(S): PRJNA292089

REPOSITORIES: GEO

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Differences in the Transcriptional Response to Fulvestrant and Estrogen Deprivation in ER-Positive Breast Cancer

Project description:Aromatase inhibitors are first-line postmenopausal agents for estrogen receptor alpha (ERa)-positive breast cancer. However, there is considerable response heterogeneity and women frequently relapse. Estrogen deprivation does not completely arrest ERa activity, and transactivation of the unliganded receptor may continue through cross-talk with growth factor pathways. In contrast with aromatase inhibitors, the selective ER downregulator fulvestrant also abrogates ligand-independent ERa activity. The benefit of fulvestrant as an alternative, combination, or sequential therapy to aromatase inhibitor has been reported, but molecular mechanisms underpinning its relative efficacy remain unclear and biomarkers for patient selection are lacking. This study demonstrates, for the first time, that the overall transcriptional response to fulvestrant is of greater magnitude than estrogen deprivation, consistent with its clinical efficacy and more complete blockade of estrogenic signaling. Using a robust integrative approach, we identify a subset of genes differentially affected by fulvestrant that comprises distinct biologic networks, correlates with antiproliferative response, and has potential utility as predictive biomarkers for fulvestrant. Global gene expression profiles from ERα-positive breast carcinomas before and during presurgical treatment with fulvestrant (n = 38) or anastrozole (n = 81), and corresponding in vitro models, were compared. Transcripts responding differently to fulvestrant and estrogen deprivation were identified and integrated using Gene Ontology, pathway and network analyses to evaluate their potential significance. --------------------------------- This represents the data for fulvestrant only

2015-08-07 | E-GEOD-71791 | biostudies-arrayexpress

Fulvestrant withdrawal from fulvestrant-resistant MCF-7/FR cells

Project description:Estrogens have been shown to elicit anti-cancer effects against estrogen receptor alpha (ER)-positive breast cancer. We sought to determine the underlying mechanism of therapeutic response. Response to 17b-estradiol was assessed in ER+ breast cancer models with resistance to estrogen deprivation: WHIM16 patient-derived xenografts, C7-2-HI and C4-HI murine mammary adenocarcinomas, and long-term estrogen-deprived MCF-7 cells. As another means to reactivate ER, the anti-estrogen fulvestrant was withdrawn from fulvestrant-resistant MCF-7 cells. Transcriptional, growth, apoptosis, and molecular alterations in response to ER reactivation were measured. 17b-estradiol treatment and fulvestrant withdrawal induced transcriptional activation of ER, and cells adapted to estrogen deprivation or fulvestrant were hypersensitive to 17b-estradiol. ER transcriptional response was followed by an unfolded protein response and apoptosis. Such apoptosis was dependent upon the unfolded protein response, p53, and JNK signaling. Anti-cancer effects were most evident in models exhibiting genomic amplification of the gene encoding ER (ESR1), suggesting that engagement of ER at high levels is cytotoxic. These data indicate that long-term adaptation to estrogen deprivation or ER inhibition alters sensitivity to ER reactivation. In such adapted cells, 17b-estradiol treatment and anti-estrogen withdrawal hyperactivate ER, which drives an unfolded protein response activation and subsequent growth inhibition and apoptosis. 17b-estradiol treatment should be considered as an alternative therapy for anti-estrogen-resistant disease, particularly in patients with tumors harboring ESR1 amplification or overexpression. Furthermore, therapeutic strategies that enhance an unfolded protein response may enhance the therapeutic effects of ER reactivation.

2019-08-19 | GSE121379 | GEO

PRO-seq analysis of estradiol, OP-1250, fulvestrant and 4OH-tamoxifen treatments at multiple timepoints in breast cancer cells

Project description:The estrogen receptor (ER) is a well-established target for the treatment of breast cancer, with the majority of patients presenting as ER-positive (ER+). Endocrine therapy is a mainstay of breast cancer treatment but the development of resistance mutations in response to aromatase inhibitors, poor pharmacokinetic properties of fulvestrant, agonist activity of tamoxifen, and limited benefit for elacestrant leave unmet needs for patients with or without resistance mutations in ESR1, the gene that encodes the ER protein. Here we describe OP-1250, a novel, orally bioavailable complete ER antagonist and selective ER degrader. OP-1250, like fulvestrant, has no agonist activity on the ER and completely blocks estrogen-induced transcriptional activity. In addition, OP-1250 demonstrates favorable biochemical binding affinity, ER degradation, and antiproliferative activity in ER+ breast cancer models that is comparable or superior to other agents of interest. OP-1250 has superior pharmacokinetic properties relative to fulvestrant, including oral bioavailability and brain penetrance, as well as superior performance in wild-type and ESR1-mutant breast cancer xenograft studies. OP-1250 combines well with cyclin-dependent kinase 4 and 6 inhibitors in xenograft studies of ER+ breast cancer models and effectively shrinks intracranially implanted tumors, resulting in prolonged animal survival. With demonstrated preclinical efficacy exceeding fulvestrant in wild-type models, elacestrant in ESR1-mutant models, and tamoxifen in intracranial xenografts, OP-1250 has the potential to benefit patients with ER+ breast cancer.

2023-09-01 | GSE241764 | GEO

GDNF-RET signaling as a target in aromatase inhibitor resistant breast cancers

Project description:Understanding the complex molecular mechanisms underlying resistance to endocrine therapy is a major challenge in the treatment of estrogen receptor-positive (ER+) breast cancers. We have previously demonstrated that glial cell line-derived neurotrophic factor (GDNF) signaling via the receptor tyrosine kinase RET promotes estrogen independent activation of ER. Here we have addressed the relevance of GDNF-RET signaling in response to aromatase inhibitor treatment and explored the efficacy of using RET inhibitors in breast cancer models of aromatase inhibitor response and resistance. A GDNF-response gene set, identified from gene expression profiling, was demonstrated to be an independent prognostic marker of poor patient outcome and, importantly, to be predictive of poor response to aromatase inhibitor treatment and development of resistance. The relevance of these findings was validated first by demonstrating an association of RET protein expression in an independent cohort of aromatase inhibitor resistant patient samples. Second, in in vitro models, GDNF-mediated RET signaling was demonstrated to enhance the survival of aromatase inhibitor resistant cells and to increase resistance in aromatase inhibitor sensitive cells. These effects could be reversed by targeting GDNF/RET signaling with the RET selective inhibitor NVP-BBT594 thus identifying GDNF-RET signaling as a potential therapeutic target, particularly in breast cancers resistant to aromatase inhibitors.<br>MCF7 cells were E2-deprived by culturing in phenol red-free RPMI 1640 supplemented with 10% DCC for 3 days and then serum-starved overnight in the presence or absence of fulvestrant (ICI182,780) (100 nM). The following day, cells were treated with GDNF (20 ng/ml) for 0, 4, 8, 24 and 48 hours in the presence or absence of fulvestrant (ICI182,780) (100 nM).

2013-01-17 | E-MEXP-3662 | biostudies-arrayexpress

Unliganded estrogen receptor alpha regulates vascular cell function and gene expression

Project description:Estrogen receptor alpha (ERa) has generally been thought to be transcriptionally inactive until it binds estrogen. Here we show that unliganded ERa, far from being transcriptionally inert, regulates a large number of genes both in vascular endothelial cells (ECs) and in mouse aorta. The genes regulated by unliganded ERa in the aorta (largely composed of smooth muscle cells) differ from those in ECs, and aorta- and EC-regulated promoters show enrichment in binding sites for distinct sets of transcription factors. In vitro, the presence of unliganded ERa decreases the migration and proliferation of ECs, and also increases proliferation of SMCs. Consistent with these effects on individual cells in vitro, mice lacking ERa, in the absence of estrogen, show significantly less SMC proliferation and medial thickening after carotid artery wire injury than ER intact mice. The effects of unliganded ERa on vascular gene expression, cell function in vitro and vascular injury responses in vivo are all reversed by the addition of estrogen. Taken together, these results indicate that unliganded ERa regulates vascular gene expression, vascular cell function, and vascular injury responses, and that the cardiovascular protective effects of estrogen may largely be due to the reversal of these effects of unliganded ERa. These results have important implications for the vascular health of men and post-menopausal women with vascular ERa and low circulating levels of estrogen. This study also raises the possibility that the steroid receptor family could have substantial hormone-independent functions in the vasculature and in other tissues.

2016-11-22 | GSE51535 | GEO

Genome-wide copy number profiling of MCF-7 and fulvestrant-resistant MCF-7/FR cells by SNP microarray.

2019-08-19 | GSE121631 | GEO

High CDK6 protects cells from fulvestrant-mediated apoptosis and is a predictor of resistance to fulvestrant in estrogen receptor-positive metastatic breast cancer

Project description:Purpose: Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer remains a major clinical problem. Recently, the CDK4/6 inhibitor palbociclib combined with letrozole was approved for treatment of ER+ advanced breast cancer, and other CDK4/6 inhibitors are being investigated in combination with different endocrine treatments. However, the role of CDK4/6 in endocrine resistance and their potential as predictive biomarkers of endocrine treatment response remains undefined. Experimental Design: We investigated the specific role of increased CDK6 expression in fulvestrant-resistant cells by gene knockdown and treatment with palbociclib, and evaluated the effect in cell proliferation, apoptosis and kinase activity. Furthermore, we evaluated CDK6 expression in metastatic samples from breast cancer patients treated or not with fulvestrant. Results: We found increased expression of CDK6 in two fulvestrant-resistant cell models vs. sensitive cells. Reduction of CDK6 expression impaired fulvestrant-resistant cell growth and induced apoptosis by reducing p70 ribosomal S6 kinase 2 activity. Treatment with palbociclib re-sensitized fulvestrant-resistant cells to fulvestrant through alteration of retinoblastoma phosphorylation. High CDK6 levels in metastatic samples from breast cancer patients treated with fulvestrant (N=45) correlated significantly with shorter progression-free survival (PFS) (p=0.0006), while no association was observed in patients receiving other endocrine treatments (N=41, p=0.874). Conclusions: Our results indicate that upregulation of CDK6 may be an important mechanism in overcoming fulvestrant-mediated growth inhibition in breast cancer cells. Patients with advanced ER+ breast cancer exhibiting high CDK6 expression in the metastatic lesions show shorter PFS upon fulvestrant treatment and thus may benefit from the addition of CDK4/6 inhibitors in their therapeutic regimens.

2017-02-08 | GSE74391 | GEO

Breast cancer cells resistant to hormone deprivation maintain an estrogen receptor alpha-dependent, E2F-directed transcriptional program

Project description:A significant fraction of breast cancers exhibit de novo or acquired resistance to estrogen deprivation. To model resistance to aromatase inhibitor (AI) therapy, long-term estrogen-deprived (LTED) derivatives of MCF-7 and HCC-1428 cells were generated through culture for 3 and 7 months under hormone-depleted conditions, respectively. These LTED cells showed sensitivity to the ER downregulator fulvestrant under hormone-depleted conditions, suggesting continued dependence upon ER signaling for hormone-independent growth. To evaluate the role of ER in hormone-independent growth, LTED cells were treated +/- 1 uM fulvestrant x 48 h before RNA was harvested for gene expression analysis. MCF-7/LTED and HCC-1428/LTED cells were treated with 10% DCC-FBS with or without the estrogen receptor antagonist drug fulvestrant for 48 hrs prior to RNA harvest for array analysis. Three replicates per condition.

2012-05-13 | E-GEOD-22533 | biostudies-arrayexpress

Expression data of hormone-responsive MCF-7 cells versus estrogen-deprived MCF-7:5C and MCF-7:2A breast cancer cells

Project description:Estrogen deprivation using aromatase inhibitors is currently the standard of care for patients with estrogen-receptor (ER)-positive breast cancer. Unfortunately, prolonged estrogen deprivation leads to drug resistance (i.e. hormone-independent growth). We therefore used DNA microarray analysis to study the gene expression profiles of wild-type MCF-7 cells (which are sensitive to antihormone therapy) and long-term estrogen deprived MCF-7:5C and MCF-7:2A breast cancer cells (which are resistance to estrogen-deprivation; aromatase inhibitor resistant). Transcriptional profiling of wild-type MCF-7 cells and estrogen deprived MCF-7:5C and MCF-7:2A cells was performed using Affymetrix Human Genome U133 Plus 2.0 Array. Keywords: breast cancer cells, estrogen

2008-03-19 | GSE10879 | GEO

Breast cancer cells resistant to hormone deprivation maintain an estrogen receptor alpha-dependent, E2F-directed transcriptional program

2012-05-14 | GSE22533 | GEO

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