Unknown,Transcriptomics,Genomics,Proteomics

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Identification of KDM3A regulated genes in the ER positive breast cancer cell line MCF-7

ABSTRACT: Using a siRNA screen we identified the histone demethylase enzyme KDM3A as a potential positive regulator of ER signalling in breast cancer. To interrogate the full extent of KDM3A regulation on ER signalling we assessed basal and estrogen (E2)- stimulated global gene expression changes in KDM3A-depleted MCF-7 cells by microarray analysis using the Illumina Human HT12 Version 4 BeadChip array. We identified ER regulated genes affected by KDM3A knockdown and determined that KDM3A is required for ER recruitment to estrogen response elements in the promotors of ER regulated genes. We also identified that KDM3A regulates expression of a number of genes involved in proliferation and that knockdown of KDM3A inhibits ER positive breast cancer cell growth. MCF-7 cells were transfected with either a non-silencing scrambled control siRNA (siSCR) or a KDM3A targeting siRNA (siKDM3A-B) using Lipfectamine RNAiMAX (Invitrogen) to a final concentration of 25 nM in steroid depleted conditions. Cells were grown for 48 hours prior to treatment with vehicle or 10 nM E2 for 4 hours before RNA extraction using TRIzol (Ambion, Life Technologies) and hybridization of triplicate samples to an Illumine HT-12 v4 BeadChip array. One sample failed due to low amounts of cRNA and was therefore not included in the analysis (siKDM3A + E2 Replicate 3). The array for replicates 1 and 2 was performed in August 2013 (Array 1) and replicate 3 in August 2014 (Array 2). When processing the data Array 2 was normalized to Array 1.

ORGANISM(S): Homo sapiens

SUBMITTER: Mark Wade

PROVIDER: E-GEOD-68918 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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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Identification of KDM3A regulated genes in the ER positive breast cancer cell line MCF-7

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