Similar to the bone marrow, the mammary gland contains a distinct population of Hoechst-effluxing side population cells, MG-SPs. To better characterize MG-SPs, their microarray gene profiles were compared to the remaining cells, which retain Hoechst dye (MG-NSPs). For analysis, gene ontology (GO) that describes genes in terms of biological processes and ontology traverser (OT) that performs enrichment analysis were utilized. OT showed that MG-SP specific genes were enriched in the GO categories of cell cycle regulation and checkpoints, multi-drug resistant transporters, organogenesis, and vasculogenesis. The MG-NSP upregulated genes were enriched in the GO category of cellular organization and biogenesis which includes basal epithelial markers, p63, smooth muscle actin (SMA), myosin, alpha-6 integrin, cytokeratin (CK) 14, as well as luminal markers, CK8 and CD24. Additional studies showed that a higher percentage of MG-SPs exist in the G1 phase of the cell cycle compared to the MG-NSPs. G1 cell cycle block of MG-SPs may be explained by higher expression of cell cycle negative regulatory genes such as TGF-beta2 (transforming growth factor-beta2), IGFBP-5 (insulin like growth factor binding protein-5), P18 INK4C and Wnt-5a (wingless-5a). Accordingly, a smaller percentage of MG-SPs expressed nuclear b-catenin, possibly as a consequence of the higher expression of Wnt-5a. In conclusion, microarray gene profiling suggests that MG-SPs are a lineage deficient mammary gland sub-population expressing key genes involved in cell cycle regulation, development and angiogenesis.
Transcriptional profiling of mammary gland side population cells.
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View SamplesSubstantial evidence implicates IGF-I signaling in the development and progression of breast cancer. To identify transcriptional targets of IGF action in breast cancer cells, we performed gene expression profiling (>22,000 RNA transcripts) of IGF-I-stimulated MCF-7 cells, a well characterized breast cancer cell line that is highly responsive to IGFs. We defined an IGF-I gene signature pattern of hundreds of genes either up-regulated or down-regulated at both 3 and 24 hrs in vitro. After removing genes considered generic to cell proliferation, the signature was examined in four different public profile datasets of clinical breast tumors (representing close to 1000 patients), as well as in profile datasets of experimental models for various oncogenic signaling pathways. Genes with early and sustained regulation by IGF-I were highly enriched for transcriptional targets of the estrogen, Ras, and PI3K/Akt/mTOR pathways. The IGF-I signature appeared activated in most estrogen receptor-negative (ER-) clinical breast tumors and in a substantial subset (~25%) of ER+ breast tumors. Patients with tumors showing activation of the IGF-I signature tended to have a shorter time to disease recurrence (including patients not receiving adjuvant therapy), both when considering all patients and the subset of ER+ patients. We found evidence for cross-talk and common transcriptional endpoints between the IGF-I and estrogen systems. Our results support the idea that the IGF-I pathway is one mechanism by which breast tumors may acquire hormone independence and a more aggressive phenotype.
Insulin-like growth factor-I activates gene transcription programs strongly associated with poor breast cancer prognosis.
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View SamplesTo 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.
Development of resistance to targeted therapies transforms the clinically associated molecular profile subtype of breast tumor xenografts.
No sample metadata fields
View SamplesTo 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.
Development of resistance to targeted therapies transforms the clinically associated molecular profile subtype of breast tumor xenografts.
No sample metadata fields
View SamplesTo 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.
Development of resistance to targeted therapies transforms the clinically associated molecular profile subtype of breast tumor xenografts.
No sample metadata fields
View SamplesHedgehog (Hh) signaling is critical for organogenesis, tissue homeostasis, and stem cell maintenance. Smoothened (SMO), the primary effector of Hh signaling, is expressed ectopically in human breast cancer, as well as in other cancers. Constitutive activation of SMO in mouse mammary glands leads to paracrine stimulation of proliferation, as well as hyperplasia. In canonical signaling, SMO functions via GLI transcription factor activation. However, recent data from Drosophila and mammalian cell lines indicate that SMO can function non-canonically as a G-protein coupled receptor (GPCR) by coupling to heterotrimeric G proteins, particularly those in the pertussis toxin (PTX)-sensitive G-alpha-i (Gai) class. Whether SMO functions as a GPCR in mammalian tissues in vivo is not known. Using genetically modified mouse models, we demonstrate here that SMO-induced stimulation of proliferation is PTX sensitive, and requires Gai2, but not Gai1 or Gai3. Our findings provide evidence for a non-canonical GPCR function of activated SMO in vivo, a finding that may have clinical significance given that most SMO-targeted agents were selected based largely on their ability to block canonical GLI-mediated transcription. Overall design: Primary mammary epithelial cell RNA was deep-sequenced from mT-mG/SmoM2;MMTV-Cre (EGFP), mT-mG/SmoM2;MMTV-Cre (tdTomato), and mT-mG/SmoM2;+ cells to examine the effects of SmoM2 overexpression in the mammary gland.
An essential role for Gα(i2) in Smoothened-stimulated epithelial cell proliferation in the mammary gland.
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View SamplesApproximately 20% of early-stage breast cancers display amplification or overexpression of the ErbB2/HER2 oncogene, conferring poor prognosis and resistance to endocrine therapy. Targeting HER2+ tumors with trastuzumab or the receptor tyrosine kinase (RTK) inhibitor lapatinib significantly improves survival, yet tumor resistance and progression of metastatic disease can develop over time. While the mechanisms of cytosolic HER2 signaling are well studied, nuclear signaling components and gene regulatory networks that bestow therapeutic resistance and limitless proliferative potential are incompletely understood. Here, we use biochemical and bioinformatics approaches to identify effectors and targets of HER2 transcriptional signaling in human breast cancer. Phosphorylation and activity of the Steroid Receptor Coactivator-3 (SRC-3) is reduced upon HER2 inhibition, and recruitment of SRC-3 to regulatory elements of endogenous genes is altered. Transcripts regulated by HER2 signaling are highly enriched with E2F1 binding sites and define a gene signature associated with proliferative breast tumor subtypes, cell cycle progression, and G1 to S phase transition. We show that HER2 signaling drives proliferation in breast cancer cells through regulation of E2F1-driven DNA metabolism and replication genes together with phosphorylation and activity of the transcriptional coactivator SRC-3. Furthermore, our analyses identified a cyclin dependent kinase (CDK) signaling node that, when targeted using the CDK4/6 inhibitor Palbociclib, defines cooperative signaling pathways for expression of tumorigenic gene networks. Our findings suggest this proliferative gene signature is amendable to pharmacological targeting. These results have implications for rational discovery of pharmacological combinations in pre-clinical models of adjuvant treatment and therapeutic resistance
HER2 Signaling Drives DNA Anabolism and Proliferation through SRC-3 Phosphorylation and E2F1-Regulated Genes.
Cell line
View SamplesThese patients proved resistant to docetaxel treatment, exhibiting residual tumor of 25% or greater remaining volume.
Gene expression profiling for the prediction of therapeutic response to docetaxel in patients with breast cancer.
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View SamplesThese patients were sensitive to docetaxel treatment, exhibiting less than 25% residual tumor.
Gene expression profiling for the prediction of therapeutic response to docetaxel in patients with breast cancer.
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View SamplesWe have performed sucrose-gradient-based isolation of polysomal fractions from untreated and TGF-beta treated MCF-10A and MCF7 cells, subjected these fractions to RNA-seq, and also sequenced total mRNA from each cell line in the treated and untreated condition Overall design: Examination of two different cell types in a treated and untreated state
CELF1 is a central node in post-transcriptional regulatory programmes underlying EMT.
Specimen part, Treatment, Subject
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