ESR1 mutations maintain higher ER pathway activity relative to vehicle and ERa-WT controls following treatment with Raloxifene or fulvestrant.
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ABSTRACT:
PROVIDER: PRJNA475477 | ENA |
REPOSITORIES: ENA
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Project description:The goal of the study was to understand whether mutations in ERa can promote resistance to various ERa antagonists of the SERD and SERM class. We found that ESR1 mutations can maintain higher ER pathway activity relative to control lines following short-term treatment with ERa antagonists raloxifene or fulvestrant.
2018-06-12 | GSE115564 | GEO
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
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.
2015-08-07 | GSE71791 | GEO
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
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
Project description:Oestrogen receptor alpha (ER, gene symbol ESR1) is the most important prognostic and treatment-predictive biomarker in breast cancer. Drugs targeting oestrogen and the ER for endocrine therapy of breast cancer include aromatase inhibitors, the selective ER modulator tamoxifen and the selective ER degrader fulvestrant. Tumours can develop resistance to endocrine therapy through several mechanisms, which is often linked to altered expression of the ER. To investigate the role of promoter methylation in regulation of ER expression, we used bisulfite sequencing to measure methylation at CpG sites in alternative ER promoter regions for six cell line models of fulvestrant resistance. Both CpG methylation and expression of alternative first exons changed dynamically with striking differences between cell lines that had stable or unstable resistance upon fulvestrant withdrawal. Methylation at some CpG sites was strongly negatively correlated with expression of specific first exons. In a breast tumour cohort, higher relative expression of upstream alternative first exons was associated with worse prognosis in post-menopausal women with ER-positive tumours who received endocrine therapy.
2024-08-06 | GSE251791 | GEO
Project description:We carried out a comparative study of the orally bioavailable investigational SERD elacestrant, versus fulvestrant, in models of endocrine sensitive and resistant BC harbouring varying genetic backgrounds. Both drugs showed comparable effects on tumour growth of ER+ patient-derived xenograft models harbouring several ESR1 mutations and elacestrant showed activity after acquired resistance to fulvestrant. Treatment with either drug showed similar impact on ER-cistrome, ER- interactome and suppression of estrogen-regulated genes, confirming the anti-estrogenic activity of elacestrant.
2022-08-01 | GSE190384 | GEO
Project description:We carried out a comparative study of the orally bioavailable investigational SERD elacestrant, versus fulvestrant, in models of endocrine sensitive and resistant BC harbouring varying genetic backgrounds. Both drugs showed comparable effects on tumour growth of ER+ patient-derived xenograft models harbouring several ESR1 mutations and elacestrant showed activity after acquired resistance to fulvestrant. Treatment with either drug showed similar impact on ER-cistrome, ER- interactome and suppression of estrogen-regulated genes, confirming the anti-estrogenic activity of elacestrant.
2022-08-01 | GSE190385 | GEO
Project description:Fulvestrant withdrawal from fulvestrant-resistant MCF-7/FR cells
| PRJNA497213 | ENA
Project description:We report the first discovery of naturally occurring ESR1Y537C and ESR1Y537S mutations in MCF7 and SUM44 ESR1-positive cell-lines after acquisition of resistance to long-term-estrogen-deprivation (LTED) and subsequent resistance to fulvestrant (ICIR).
2018-01-12 | GSE100075 | GEO