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Under conditions of hormonal adjuvant treatment the estrogen receptor apoprotein supports breast cancer cell cycling through the retinoic acid receptor α1 apoprotein

ABSTRACT: Under conditions of hormonal adjuvant treatment the estrogen receptor apoprotein supports breast cancer cell cycling through the retinoic acid receptor α1 apoprotein. Basal proliferation persisted in estrogen-sensitive breast cancer cells grown in hormone depleted conditioned media without or with 4-hydroxytamoxifen (OH-Tam). Downregulating ER using siRNA inhibited basal proliferation by promoting cell cycle arrest. The basal expression of RARα1, the only RARα isoform that was expressed in breast cancer cell lines and in most breast tumors, was supported by apo-ER but was unaffected by OH-Tam. The overlapping tamoxifen-insensitive gene regulation by apo-ER and apo-RARα1 comprised activation of mainly genes promoting cell cycle and mitosis and suppression of genes involved in growth inhibition.

ORGANISM(S): Homo sapiens

PROVIDER: GSE26298 | GEO | 2011/05/13

SECONDARY ACCESSION(S): PRJNA135127

REPOSITORIES: GEO

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Under conditions of hormonal adjuvant treatment the estrogen receptor apoprotein supports breast cancer cell cycling through the retinoic acid receptor M-NM-11 apoprotein

Project description:Under conditions of hormonal adjuvant treatment the estrogen receptor apoprotein supports breast cancer cell cycling through the retinoic acid receptor M-NM-11 apoprotein. Basal proliferation persisted in estrogen-sensitive breast cancer cells grown in hormone depleted conditioned media without or with 4-hydroxytamoxifen (OH-Tam). Downregulating ER using siRNA inhibited basal proliferation by promoting cell cycle arrest. The basal expression of RARM-NM-11, the only RARM-NM-1 isoform that was expressed in breast cancer cell lines and in most breast tumors, was supported by apo-ER but was unaffected by OH-Tam. The overlapping tamoxifen-insensitive gene regulation by apo-ER and apo-RARM-NM-11 comprised activation of mainly genes promoting cell cycle and mitosis and suppression of genes involved in growth inhibition. Cells were plated at 20% confluence in low glucose phenol red free medium supplemented with 5% charcoal stripped FBS and glutamine 24h-48h prior to transfection. Treatment with vehicle, OH-Tam (100nM), or OH-Tam (500nM) was begun an additional 24h later. Cells were transfected with control siRNA, ERM-NM-1 siRNA or RARM-NM-1 siRNA.

2011-05-13 | E-GEOD-26298 | biostudies-arrayexpress

Regulation of KMT2D by PI(3)K/AKT signalling orchestrates oestrogen receptor mediated transcriptional activation in breast cancer

Project description:We aim to elucidate the mechanisms of how PI3K inhibition is promoting estrogen receptor (ER) activation and ER dependency in breast cancer.

2017-04-01 | GSE95366 | GEO

A novel bystander effect in tamoxifen treatment: PPIB derived from ER+ cells attenuates ER- cells via endoplasmic reticulum stress-induced apoptosis

Project description:Tamoxifen (TAM) is the frontline therapy for estrogen receptor-positive (ER+) breast cancer in premenopausal women that interrupts ER signaling. As tumors with elevated heterogeneity, amounts of ER-negative (ER-) cells are present in ER+ breast cancer that cannot be directly killed by TAM. Despite complete remissions have been achieved in clinical practice, the mechanism underlying the elimination of ER- cells during TAM treatment remains an open issue. Herein, we deciphered the elimination of ER- cells in TAM treatment from the perspective of the bystander effect. Markable reductions were observed in tumorigenesis of ER- breast cancer cells by applying both supernatants from TAM-treated ER+ cells and a transwell co-culture system, validating the presence of a TAM-induced bystander effect. The major antitumor protein derived from ER- cells, peptidyl-prolyl cis-trans isomerase B (PPIB), is the mediator of the TAM-induced bystander effect identified by quantitative proteomics. The attenuation of ER- cells was attributed to activated BiP/eIF2α/CHOP axis and promoted endoplasmic reticulum stress (ERS)-induced apoptosis, which can also be triggered by PPIB independently. Altogether, our study revealed a novel TAM-induced bystander effect in TAM treatment of ER+ breast cancer, raising the possibility to develop PPIB as a synergistic antitumor agent or even substitute endocrine therapy.

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Cooperative interaction between retinoic acid receptor-alpha and estrogen receptor in breast cancer.

Project description:Retinoic acid receptor-alpha (RAR alpha) is a known estrogen target gene in breast cancer cells. The consequence of RAR alpha induction by estrogen was previously unknown. We now show that RAR alpha is required for efficient estrogen receptor-alpha (ER)-mediated transcription and cell proliferation. RAR alpha can interact with ER-binding sites, but this occurs in an ER-dependent manner, providing a novel role for RAR alpha that is independent of its classic role. We show, on a genome-wide scale, that RAR alpha and ER can co-occupy regulatory regions together within the chromatin. This transcriptionally active co-occupancy and dependency occurs when exposed to the predominant breast cancer hormone, estrogen--an interaction that is promoted by the estrogen-ER induction of RAR alpha. These findings implicate RAR alpha as an essential component of the ER complex, potentially by maintaining ER-cofactor interactions, and suggest that different nuclear receptors can cooperate for effective transcriptional activity in breast cancer cells. RAR alpha silenced breast cancer MCF-7 cell lines or control siRNA in the presence of estrogen or a vehicle. MCF-7 cells were hormone-depleted for 3 d and treated with 100 nM estrogen for 12 h. There were three biological replicates for each of the four different groups.

2010-06-16 | E-GEOD-22213 | biostudies-arrayexpress

H4K12ac is regulated by estrogen receptor-alpha and is associated with BRD4 function and inducible transcription

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2015-05-02 | E-GEOD-65886 | biostudies-arrayexpress

Inhibition of CDK8 Mediator Kinase Suppresses Estrogen Receptor Signaling and Growth of Estrogen Receptor Positive Breast Cancer

Project description:Hormone therapy targeting estrogen receptor (ER) is the principal treatment for ER-positive breast cancers but many cancers develop resistance to anti-estrogens. Cyclin-dependent kinase 8 (CDK8) is a transcriptional regulator of several oncogenic pathways. Expression levels of CDK8 and ERα are inversely correlated in breast cancers suggesting a functional association between CDK8 and ER. CDK8 inhibition by selective small-molecule inhibitors, by shRNA knockdown or by CRISPR-Cas9 knockout suppressed estrogen-induced transcription, with no significant effects on ERα protein expression or phosphorylation. CDK8 inhibition also abrogated the mitogenic effect of estrogen on ER-positive breast cancer cells and potentiated growth inhibition by the ER antagonist fulvestrant. In vivo, administration of a CDK8 inhibitor suppressed ER-positive breast cancer xenograft growth and augmented the effects of fulvestrant with no apparent toxicity. CDK8 inhibitors also suppressed the development of estrogen independence in ER-positive breast cancer cells. These results identify CDK8 as a novel drug target for breast cancer therapy.

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Transcription profiling of human in vivo xenograft models of estrogen receptor-positive (ER+) breast cancer, with or without HER2 over-expression (MCF7/HER2-18 and MCF7 wt, respectively)

Project description:To investigate molecular mechanisms of resistance, we used two different in vivo xenograft models of estrogen receptor-positive (ER+) breast cancer, with or without HER2 over-expression (MCF7/HER2-18 and MCF7 wt, respectively). Mice with established tumors were assigned to the following treatment groups: continued estrogen supplementation (E2), estrogen deprivation (ED), ED plus tamoxifen (Tam), all with or without the EGFR tyrosine kinase inhibitor gefinitinib (G). Another group received ED plus the antiestrogen fulvestrant (MCF7 wt only). Tumors with acquired or de novo resistance to these endocrine therapies were profiled for mRNA expression using Affymetrix Genechip arrays. Experiment Overall Design: MCF7 xenografts were established in ovariectomized five to six week-old nu/nu athymic nude mice supplemented with 0.25 mg 21 day release estrogen pellets by inoculating subcutaneously (s.c.) 5E-6 cells. When tumors reached the size of 150-200 mm3 (3-5 weeks), the animals were randomly allocated to continued estrogen (E2), continued estrogen with gefitinib (E2+G; 100mg/kg, 5 days/week), estrogen withdrawal alone (ED; by removal of the estrogen pellets), and estrogen withdrawal plus tamoxifen citrate (Tam; 500 microg/animal s.c. in peanut oil, 5 days/week), with either gefitinib (Tam+G; 100mg/kg, 5 days/week) or vehicle (1% Tween 80) administered via gavage, as well as estrogen withdrawal plus fulvestrant (ICI 182,780) in the MCF7 wt model (Fulv; 5mg/mouse s.c. once weekly), and estrogen withdrawal with gefitinib (ED+G). Tumors were harvested for molecular studies when they became resistant to treatment and reached the size of 1000 mm3 (n=7).

2009-01-13 | E-GEOD-8139 | biostudies-arrayexpress

Cooperative interaction between retinoic acid receptor-alpha and estrogen receptor in breast cancer.

2010-06-09 | GSE22213 | GEO

Estrogen Receptor Positive Breast Cancer: Aromatase Inhibitor Response Study

Project description:<p>Highly variable outcomes are observed in patients with estrogen receptor positive (ER+) breast cancer who undergo preoperative estrogen deprivation therapy with aromatase inhibitors (AI). In this study, 46 baseline tumor and normal genomes and 31 baseline tumor/normal exomes of participants selected from two clinical trials of neoadjuvant AI therapy on ER+ breast cancer were sequenced to identify somatic alterations that correlate with response to AI, to screen for therapeutic targets and to elucidate the genetic landscape of ER+ breast cancer. From the same set of patients we later performed deep genomic characterization of a subset of matched primary tumors after four months of AI therapy, generating comprehensive information about the range of changes that occur when ER+ breast cancers are subjected to estrogen deprivation. This data includes whole genome sequence and transcriptome data. To better understand tumor heterogeneity and the evolution of resistance to estrogen-deprivation therapy, a subset of these tumours, along with 38 additional cases were sequenced to greater depth using targeted capture with a gene panel.</p>

| phs000472 | dbGaP

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