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LRH-1 governs vital transcriptional programs in endocrine sensitive and resistant breast cancer cells: Expression profiling

ABSTRACT: Tumor characteristics are decisive in the determination of treatment strategy for breast cancer patients. Patients with estrogen receptor-α (ERα) positive breast cancer can benefit from long-term hormonal treatment. Nonetheless, the majority of patients will develop resistance to these therapies. Here, we investigated the role of the liver receptor homolog-1 (LRH-1, NR5A2) in anti-estrogen (AE) sensitive and resistant breast cancer cells. We identified genome-wide LRH-1 binding sites using ChIP-seq, uncovering preferential binding to regions distal to transcriptional start sites (TSS). We further characterized these LRH-1 binding sites by integrating overlapping layers of specific chromatin marks, revealing that many LRH-1 binding sites are active and could be involved in long-range enhancer-promoter looping. Combined with transcriptome analysis of LRH-1 depleted cells, these results show that LRH-1 regulates specific subsets of genes involved in cell proliferation in AE-sensitive and AE-resistant breast cancer cells. Furthermore, the LRH-1 transcriptional program is highly associated with signature of poor outcome breast cancer tumors in vivo. Herein report the genome-wide location and molecular function of LRH-1 in breast cancer cells and reveal its therapeutic potential for the treatment of breast cancers, notably for tumors resistant to treatments currently used in therapies. Total RNA was obtained from two biological replicates of breast cancer cells MCF7, LCC2 and LCC9 transduced with LRH-1 shRNA (shLRH-1) or control shRNA (shCTL) lentiviruses.

ORGANISM(S): Homo sapiens

SUBMITTER: Bianco S

PROVIDER: S-ECPF-GEOD-54891 | biostudies-other | 2014 Apr

REPOSITORIES: biostudies-other

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Project description:BackgroundMicroRNAs (miRs) regulate gene expression through translation inhibition of target mRNAs. One of the most promising approaches for cancer therapy is through mimicking or antagonizing the action of miRs. In this report, we analyzed the miRnome profile of several human breast cancer cell lines to determine the influence of estrogen receptor (ER) silencing previously shown to result in epithelial to mesenchymal transition (EMT) and enhanced tumor invasion.MethodsMicroRNA extracted from MDA-MB-231 (de novo ER-) and ER-silenced (acquired ER-) pII and IM-26 or ER-expressing (YS1.2) siRNA transfected derivatives of MCF7 cells was deep sequenced on Illumina NextSeq500. Respective miRnomes were compared with edgeR package in R and Venny2.1 and target prediction performed with miRTarBase. Mimics and inhibitors of selected differentially expressed miRs associated with EMT mediators (miR-200c-3p targeting ZEB1, miR-449a targeting δ-catenin and miR-29a-3p) were transfected into pII cells and mRNA targets, as well as E-cadherin and keratin 19 (epithelial and mesenchymal markers respectively) were measured using taqman PCR.ResultsEach cell line expressed about 20% of the total known human miRnome; There was a high degree of similarity between the 3 tested ER-lines. Out of these expressed miRs, 50-60% were significantly differentially expressed between ER- and ER + lines. Transfection of miR-200c-3p mimic into pII cells down regulated ZEB1 and vimentin, and increased E-cadherin and keratin 19 with accompanying morphological changes, and reduced cell motility, reflecting a reversal back into an epithelial phenotype. On the other hand, transfecting pII with miR-449a inhibitor reduced cell invasion but did not induce EMT. Transfecting pII cell line with the mimic or inhibitor of miR-29a-3p showed no change in EMT markers or cell invasion suggesting that the EMT induced by loss of ER function can be reversed by blocking some but not just any random EMT-associated genes.ConclusionsThese data suggest that differences in miR expression can be exploited not only as mediators (using mimics) and targets (using miR antagonists) for general cancer therapies aimed at regulating either individual or multiple mRNAs, but also to re-sensitize endocrine resistant breast cancers by turning them back into a type that will be susceptible to endocrine agents.

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LRH-1 governs vital transcriptional programs in endocrine sensitive and resistant breast cancer cells: Expression profiling

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