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Expression data from MCF-7 cells stimulated by Estrogen or IGF-I

ABSTRACT: Although estrogen receptor (ER) and insulin-like growth factor (IGF) signaling are important for normal mammary development and breast cancer, cross-talk between these pathways, particularly at the level of gene transcription, remains poorly understood. We performed microarray analysis on MCF-7 breast cancer cells treated with estradiol (E2) or IGF-I for 3hr or 24hr. IGF-I regulated mRNA of 5-10-fold more genes than estradiol, and many genes were co-regulated by both ligands. Importantly, expression of these co-regulated genes correlated with poor prognosis of human breast cancer. Closer examination revealed enrichment of repressed transcripts. Interestingly, a number of potential tumor suppressors were down-regulated by IGF-I and estradiol. In fact, BLNK, one of the top repressed genes, is a potential growth suppressor in breast cancer cells. Analysis of three down-regulated genes showed that E2-mediated repression occurred independently of IGF-IR, and IGF-I-mediated repression occurred independently of ER. However, repression by IGF-I or estradiol required common downstream kinases. In conclusion, E2 and IGF-I co-regulate a set of genes that affect breast cancer outcome. There is enrichment of repressed transcripts, and the down-regulation is independent at the receptor level. This may be important clinically, as tumors with active ER and IGF-IR signaling may require co-targeting of both pathways. KEYWORDS: multiple group comparison

ORGANISM(S): Homo sapiens

PROVIDER: GSE26834 | GEO | 2011/05/09

SECONDARY ACCESSION(S): PRJNA136041

REPOSITORIES: GEO

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Project description:Estrogen receptors play critical roles in both the normal physiological, and disease states of numerous tissues, including breast and uterus. Estrogen receptor alpha (ER) can activate or repress the expression of target genes upon estrogen stimulation. In order to better understand the transcriptional network of ER in breast and uterus, we generated genome wide maps ofM-BM- ER binding sites (ERBS) and gene expression profiles in breast cancer cells (MCF7 and T47D) and uterine cancer cells (ECC1 and Ishikawa) through ChIP-Seq and microarray techniques. Surprisingly, we identified large scale differences in the numbers of ERBS between these cell lines when treated with E2 (17-M-NM-2 estradiol). Besides identification of common and unique ERBS between breast and uterine cancer cell types., our data also suggest that both cell types could recruit a large set of common co-operating transcription factors (Co-TFs) and a few unique Co-TFs as well. Besides the genes that are commonly regulatedM-BM- between the different cell lines, there are a number of genes that are differentially regulated in different cell types. Gene pathway analyses of E2 target genes suggest that ER regulates many biological pathways and processes in both tissue-type dependent and independent manners. Our results showed that cell lines derived from same tissue display a greater similarity for both profiles of ERBS and gene expression, and that the differential profiles of ER and preferential recruitment of some Co-TFs are the main determinants for the differential regulation of E2 signaling in breast and uterine cancer cells. In order to explore common and distinctive features of ERM-NM-1 (estrogen receptor alpha) binding profiles between breast and uterus, we generated eight ChIP-Seq libraries for the four cell lines (MCF7, T47D, ECC1 and Ishikawa) under two different treatments (E2, ethanol). In addition, we generated four control libraries for the four cell lines. For all treatment libraries, we generated about 7-12 million unique tags each. ER antibody catalog number is (Santa Cruz,sc-543).

Project description:Altered expression of microRNAs (miRNAs), an abundant class of small non-protein-coding RNAs that mostly function as negative regulators of protein-coding gene expression, is common in cancer. Here we analyze the regulation of miRNA expression in response to estrogen, a steroid hormone that is involved in the development and progression of breast carcinomas and that is acting via the estrogen receptors (ER) transcription factors. We set out to thoroughly describe miRNA expression, by using miRNA microarrays and real time RTPCR experiments, in various breast tumor cell lines in which estrogen signaling has been induced by 17β-estradiol (E2). We show that the expression of a broad set of miRNAs decreases following E2 treatment in an ER-dependent manner. We further show that enforced expression of several of the repressed miRNAs reduces E2-dependent cell growth, thus linking expression of specific miRNAs with estrogen-dependent cellular response. In addition, a transcriptome analysis revealed that the E2-repressed miR-26a and miR-181a regulate many genes associated with cell growth and proliferation, including the progesterone receptor gene, a key actor in estrogen signaling. Strikingly, miRNA expression is also regulated in breast cancers of women who had received antiestrogen neoadjuvant therapy thereby showing an estrogen-dependent in vivo regulation of miRNA expression. Overall, our data indicates that the extensive alterations in miRNA regulation upon estrogen signalling pathway plays a key role in estrogen-dependent functions and highlights the utility of considering miRNA expression in the understanding of antiestrogen resistance of breast cancer. 9 samples analyzed. Triplicates were done. MCF-7+miR26a+E2 (n=1 to 3) ; MCF7+miRctrl+E2 (n=1 to 3) ; MCF7+miRctrl+vehicle (n=1 to 3). We generated pairwise comparisons using EASANA from GenoSplice technology: MCF-7+miR26a+E2 versus MCF7+miRctrl+E2 and MCF-7+miRctrl+E2 versus MCF7+miRctrl+vehicle. Fold change ≥1.5 were selected.

Project description:MCF-7:PF is a a new in vitro model of antihormone resistant breast cancer that exhibits the characteristics of acquired tamoxifen resistance in vivo. It is well known that estrogen (E2) induces apoptosis in long-term estrogen-deprived breast cancer cells, MCF-7:5C (PubMed References PMID:15862958, PMID:16333030). MCF-7:PF was derived from MCF-7:5C through inhibition of c-Src, which blocks E2-induced apoptosis, coverts E2 responses from apoptosis to proliferation. MCF-7:PF cell growth is stimulated by E2 and SERMS in an ERα-dependent manner. Abstract: A c-Src inhibitor blocks estrogen (E2)-induced stress and converts E2 responses from inducing apoptosis to stimulating growth in E2-deprived breast cancer cells. A resulting cell line, MCF-7:PF, is reprogrammed with features of functional estrogen receptor (ER) and over-expression of insulin-like growth factor-1 receptor beta (IGF-1Rβ). We addressed the question of whether the antiestrogenic selective ER modulator 4-hydroxytamoxifen (4-OHT) could target ER to prevent E2-stimulated growth in MCF-7:PF cells. Unexpectedly, 4-OHT stimulated cell growth in an ER-dependent manner. However, unlike E2, 4-OHT suppressed classic ER-target genes as does the pure antiestrogen ICI 182,780, even during growth stimulation. Chromatin-immunoprecipitation (ChIP) assay indicated that 4-OHT did not recruit ER or nuclear receptor coactivator 3 (SRC3) to the promoter of ER-target gene, pS2. Paradoxically, 4-OHT reduced total IGF-1Rβ but increased phosphorylation of IGF-1Rβ, which was responsible for the activation of the phosphatidylinositol-3 kinases (PI3K)/Akt signaling pathway. Mechanistic studies revealed that 4-OHT rapidly activated the non-genomic pathway through ER, but other membrane-associated proteins such as IGF-1Rβ and c-Src participated. Furthermore, 4-OHT was more potent than E2 to up-regulate membrane remodeling molecules and activated focal adhesion molecules to promote cell growth. Therefore, disruption of membrane-associated signaling completely abolished 4-OHT-stimulated cell growth, but not E2-stimulated cell growth. Despite continued suppression of classic ER-target genes, 4-OHT activated the complex network of cytoskeleton remodeling and extracellular matrix-related signaling which facilitated 4-OHT-stimulated cell growth. This study is the first to recapitulate a cellular model in vitro of acquired tamoxifen (TAM) resistance developed in athymic mice in vivo.

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Expression data from MCF-7 cells stimulated by Estrogen or IGF-I

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