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Identification of the KDM4B regulated transcriptome in the ER positive breast cancer cell line MCF-7

ABSTRACT: To elucidate the KDM4B regulated transcriptomes in ER-positive breast cancer cells we assessed global gene expression changes in KDM4B-depleted MCF-7 cells by microarray analysis using the Illumina Human HT12 Version 4 BeadChip array. Differentially expressed genes were compared with KDM3A and FOXA1 regulated transcriptomes. We identified 229 genes co-regulated by all three enzymes and that co-regulated genes were involved in cell cycle processes. We identified that 53% and 48% of KDM4B-regulated genes were also regulated by KDM3A and FOXA1, with co-regulatory gene signatures being involved with estrogen response signatures and cell proliferation. We also identified that depletion of KDM3A and KDM4B together inhibits ER-target gene expression and ER-positive breast cancer cell growth more than depletion of either gene on its own.

ORGANISM(S): Homo sapiens

PROVIDER: GSE135427 | GEO | 2019/08/06

REPOSITORIES: GEO

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Project description:Breast cancer is a heterogeneous disease comprised of at least five major subtypes. Luminal subtype tumors confer a more favourable patient prognosis, which is in part, attributed to the Estrogen Receptor-alpha (ER) positivity and anti-hormone responsiveness of these tumors. Expression of the forkhead box transcription factor, FOXA1, also correlates with the luminal subtype and patient survival, but is present in a subset of ER-negative tumors. Similarly, FOXA1 is consistently expressed in luminal breast cancer cell lines even in the absence of ER. In contrast, basal breast cancer cell lines do not express FOXA1, and loss of FOXA1 in luminal cells increases migration and invasion, characteristics of the basal subtype. To delineate an ER-independent role for FOXA1 in maintaining the luminal phenotype, and hence a more favourable prognosis, we performed cDNA microarray analyses on luminal FOXA1-positive, ER-positive (MCF7, T47D) and FOXA1-positive, ER-negative (MDA-MB-453, SKBR3) cell lines in the presence or absence of transient FOXA1 silencing. This resulted in three FOXA1 transcriptomes: (1) a luminal-signature (consistent across cell lines), (2) an ER-positive signature (restricted to MCF7 and T47D) and (3) an ER-negative signature (restricted to MDA-MB-453 and SKBR3). Use of Gene Set Enrichment Analyses (GSEA) as a phenotyping tool revealed that FOXA1 silencing resulted in a transcriptome shift from luminal to basal gene expression signatures. FOXA1 binds to both luminal and basal genes within luminal breast cancer cells, suggesting that it not only transactivates luminal genes, but also represses basal-associated genes. From these results we conclude that FOXA1 controls plasticity between basal and luminal cells, playing a dominant role in repressing the basal phenotype, and thus tumor aggressiveness, in luminal breast cancer cells. Although it has been proposed that FOXA1-targeting agents may be useful for treating luminal tumors, these data suggest that this approach may promote transitions toward a more aggressive cancer. FOXA1 siRNA treated breast cell lines compared directly to nonspecific siRNA treated cell lines using Agilent 4X44 microarrays.

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Identification of the KDM4B regulated transcriptome in the ER positive breast cancer cell line MCF-7

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