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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

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

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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

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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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