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Proximal and distal regulation of the HYAL1 gene cluster by the estrogen receptor ? in breast cancer cells.

ABSTRACT: Chromosomal and genome abnormalities at the 3p21.3 locus are frequent events linked to epithelial cancers, including ovarian and breast cancers. Genes encoded in the 3p21.3 cluster include HYAL1, HYAL2 and HYAL3 members of hyaluronidases involved in the breakdown of hyaluronan, an abundant component of the vertebrate extracellular matrix. However, the transcriptional regulation of HYAL genes is poorly defined. Here, we identified the estrogen receptor ER? as a negative regulator of HYAL1 expression in breast cancer cells. Integrative data mining using METABRIC dataset revealed a significant inverse correlation between ER? and HYAL1 gene expression in human breast tumors. ChIP-Seq analysis identified several ER? binding sites within the 3p21.3 locus, supporting the role of estrogen as an upstream signal that diversely regulates the expression of 3p21.3 genes at both proximal and distal locations. Of these, HYAL1 was repressed by estrogen through ER? binding to a consensus estrogen response element (ERE) located in the proximal promoter of HYAL1 and flanked by an Sp1 binding site, required to achieve optimal estrogen repression. The repressive chromatin mark H3K27me3 was increased at the proximal HYAL1 ERE but not at other EREs contained in the cluster, providing a mechanism to selectively downregulate HYAL1. The HYAL1 repression was also specific to ER? and not to ER?, whose expression did not correlate with HYAL1 in human breast tumors. This study identifies HYAL1 as an ER? target gene and provides a functional framework for the direct effect of estrogen on 3p21.3 genes in breast cancer cells.

SUBMITTER: Edjekouane L

PROVIDER: S-EPMC5363586 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Proximal and distal regulation of the HYAL1 gene cluster by the estrogen receptor α in breast cancer cells.

Edjekouane Lydia L Benhadjeba Samira S Jangal Maïka M Fleury Hubert H Gévry Nicolas N Carmona Euridice E Tremblay André A

Oncotarget 20161101 47

Chromosomal and genome abnormalities at the 3p21.3 locus are frequent events linked to epithelial cancers, including ovarian and breast cancers. Genes encoded in the 3p21.3 cluster include HYAL1, HYAL2 and HYAL3 members of hyaluronidases involved in the breakdown of hyaluronan, an abundant component of the vertebrate extracellular matrix. However, the transcriptional regulation of HYAL genes is poorly defined. Here, we identified the estrogen receptor ERα as a negative regulator of HYAL1 express ...[more]

PMID: 27764788

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Project description:BACKGROUND: Estrogen receptors alpha (ER?) and beta (ER?) are transcription factors (TFs) that mediate estrogen signaling and define the hormone-responsive phenotype of breast cancer (BC). The two receptors can be found co-expressed and play specific, often opposite, roles, with ER? being able to modulate the effects of ER? on gene transcription and cell proliferation. ER? is frequently lost in BC, where its presence generally correlates with a better prognosis of the disease. The identification of the genomic targets of ER? in hormone-responsive BC cells is thus a critical step to elucidate the roles of this receptor in estrogen signaling and tumor cell biology. RESULTS: Expression of full-length ER? in hormone-responsive, ER?-positive MCF-7 cells resulted in a marked reduction in cell proliferation in response to estrogen and marked effects on the cell transcriptome. By ChIP-Seq we identified 9702 ER? and 6024 ER? binding sites in estrogen-stimulated cells, comprising sites occupied by either ER?, ER? or both ER subtypes. A search for TF binding matrices revealed that the majority of the binding sites identified comprise one or more Estrogen Response Element and the remaining show binding matrixes for other TFs known to mediate ER interaction with chromatin by tethering, including AP2, E2F and SP1. Of 921 genes differentially regulated by estrogen in ER?+ vs ER?- cells, 424 showed one or more ER? site within 10 kb. These putative primary ER? target genes control cell proliferation, death, differentiation, motility and adhesion, signal transduction and transcription, key cellular processes that might explain the biological and clinical phenotype of tumors expressing this ER subtype. ER? binding in close proximity of several miRNA genes and in the mitochondrial genome, suggests the possible involvement of this receptor in small non-coding RNA biogenesis and mitochondrial genome functions. CONCLUSIONS: Results indicate that the vast majority of the genomic targets of ER? can bind also ER?, suggesting that the overall action of ER? on the genome of hormone-responsive BC cells depends mainly on the relative concentration of both ERs in the cell.

Project description:BackgroundEstrogens are known to regulate the proliferation of breast cancer cells and to modify their phenotypic properties. Identification of estrogen-regulated genes in human breast tumors is an essential step toward understanding the molecular mechanisms of estrogen action in cancer. To this end we generated and compared the Serial Analysis of Gene Expression (SAGE) profiles of 26 human breast carcinomas based on their estrogen receptor alpha (ER) status. Thus, producing a breast cancer SAGE database of almost 2.5 million tags, representing over 50,000 transcripts.ResultsWe identified 520 transcripts differentially expressed between ERalpha-positive (+) and ERalpha-negative (-) primary breast tumors (Fold change >or= 2; p < 0.05). Furthermore, we identified 220 high-affinity Estrogen Responsive Elements (EREs) distributed on the promoter regions of 163 out of the 473 up-modulated genes in ERalpha (+) breast tumors. In brief, we observed predominantly up-regulation of cell growth related genes, DNA binding and transcription factor activity related genes based on Gene Ontology (GO) biological functional annotation. GO terms over-representation analysis showed a statistically significant enrichment of various transcript families including: metal ion binding related transcripts (p = 0.011), calcium ion binding related transcripts (p = 0.033) and steroid hormone receptor activity related transcripts (p = 0.031). SAGE data associated with ERalpha status was compared with reported information from breast cancer DNA microarrays studies. A significant proportion of ERalpha associated gene expression changes was validated by this cross-platform comparison. However, our SAGE study also identified novel sets of genes as highly expressed in ERalpha (+) invasive breast tumors not previously reported. These observations were further validated in an independent set of human breast tumors by means of real time RT-PCR.ConclusionThe integration of the breast cancer comparative transcriptome analysis based on ERalpha status coupled to the genome-wide identification of high-affinity EREs and GO over-representation analysis, provide useful information for validation and discovery of signaling networks related to estrogen response in this malignancy.

Dataset Information

Proximal and distal regulation of the HYAL1 gene cluster by the estrogen receptor ? in breast cancer cells.

Publications

Proximal and distal regulation of the HYAL1 gene cluster by the estrogen receptor α in breast cancer cells.

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