The estrogen receptor-a (ERa) is a transcription factor which plays a critical role in controlling cell proliferation and tumorigenesis by recruiting various cofactors to estrogen response elements (EREs) to induce or repress gene transcription. A deeper understanding of these transcriptional mechanisms may uncover novel therapeutic targets for ERa-dependent cancers. Here we show for the first time that BRD4 regulates ERa-induced gene expression by affecting elongation-associated phosphorylation of RNA Polymerase II (RNAPII P-Ser2) and histone H2B monoubiquitination (H2Bub1). Consistently, BRD4 activity is required for estrogen-induced proliferation of ER+ breast and endometrial cancer cells and uterine growth in mice. Genome-wide occupancy studies revealed an enrichment of BRD4 on transcriptional start sites as well as EREs enriched for H3K27ac and demonstrate a requirement for BRD4 for H2B monoubiquitination in the transcribed region of estrogen-responsive genes. Importantly, we further demonstrate that BRD4 occupancy correlates with active mRNA transcription and is required for the production of ERa-dependent enhancer RNAs (eRNAs). These results uncover BRD4 as a central regulator of ERa function and potential therapeutic target. Overall design: mRNA expression profiles of MCF7 cells treated with +/- estrogen treatment under negative control siRNA, BRD4 siRNA or JQ1 treatment, in duplicates.
Bromodomain protein BRD4 is required for estrogen receptor-dependent enhancer activation and gene transcription.
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View SamplesResistance towards anti-angiogenic therapy (AAT) still represents a substantial clinical challenge. We report here that tumor-infiltrating mast cells (MC) are powerful mediators decreasing efficacy of AAT in mice and cancer patients. They act in a cell-extrinsic manner by secreting granzyme B, which liberates pro-angiogenic mediators from the extracellular matrix. In addition, MC also diminish efficacy of anti-angiogenic agents in a cell-autonomous way, which can be blocked by the mast cell degranulation inhibitor cromolyn. Our findings are relevant in humans because patients harboring higher numbers of MC in their tumors have an inferior outcome after anti-angiogenic treatment in the Gepar Quinto randomized Phase 3 clinical trial. Thus, MC-targeting might represent a novel promising approach to increase efficacy of AAT.
Mast cells decrease efficacy of anti-angiogenic therapy by secreting matrix-degrading granzyme B.
Specimen part
View SamplesThe tumorigenicity of human pluripotent stem cells (hPSCs) is a major safety concern for their application in regenerative medicine. Here we identify the tight-junction protein Claudin-6 as a specific cell surface marker of hPSCs that can be used to selectively remove Claudin-6-positive cells from mixed cultures. We show that Claudin-6 is absent in adult tissues but highly expressed in undifferentiated cells, where it is dispensable for hPSC survival and self-renewal. We use three different strategies to remove Claudin-6-positive cells from mixed populations: an antibody against Claudin-6; a cytotoxin-conjugated antibody that selectively targets undifferentiated cells; and clostridium perfringens enterotoxin, a toxin that binds several Claudins, including Claudin-6, and efficiently kills undifferentiated cells, thus eliminating the tumorigenic potential of hPSC-containing cultures. This work provides a proof of concept for the use of Claudin-6 to eliminate residual undifferentiated hPSCs from culture, highlighting a strategy that may increase the safety of hPSC-based cell therapies.
Immunologic and chemical targeting of the tight-junction protein Claudin-6 eliminates tumorigenic human pluripotent stem cells.
Specimen part, Cell line
View SamplesPluripotent-specific inhibitors (PluriSIns) make a powerful tool for studying the mechanisms that control the survival of human pluripotent stem cells (hPSCs). Here we characterize PluriSIn#2 as a novel selective indirect inhibitor of topoisomerase II alpha (TOP2A). We find that TOP2A is uniquely expressed in undifferentiated hPSCs, and that its inhibition results in their rapid cell death. These findings reveal a dependency of hPSCs on the activity of TOP2A, which can be harnessed for their selective elimination from culture.
Brief reports: Controlling the survival of human pluripotent stem cells by small molecule-based targeting of topoisomerase II alpha.
Specimen part, Cell line, Treatment
View SamplesWe aimed to determine whether overexpression of endoderm-specific miRNA may affect hESC differentiation. To this end, we analyzed the effect of lentiviral-based overexpression of liver-specific miR-122 on hESC differentiation, using genomewide gene microarrays. Stable overexpression of endoderm-specific miR-122 in hESC resulted in increased expression of a few endodermal markers in spontaneously-differentiating hESC, but had no clear effect on directing differentiation towards an endodermal fate; rather, it delayed the general differentiation of hESC.
MicroRNA expression patterns and function in endodermal differentiation of human embryonic stem cells.
Cell line
View SamplesPD is the second most common neurodegenerative disease worldwide with growing prevalence. MPTP is a neurotoxin which causes the appearance of Parkinson's disease (PD) pathology. The involvement of the cholinergic system in PD has been identified decades ago and anti-cholinergic drugs were upon the first drugs used for symptomatic treatment of PD. Of note, MPTP intoxication is a model of choice for symptomatic neuroprotective therapies since it have been quite predictive. Mice were exposed to the dopaminergic neurotoxin 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP), with or without the protective acetylcholinesterase (AChE-R) variant. Transgenic AChE-S (the synaptic variant), AChE-R (the shorter, protective variant) and FVB/N control mice were included in this study. Two brain regions were examined: the pre-frontal cortex (PFC) and the striatal caudate-putamen (CPu). Each condition (i.e brain region and transgenic variant) was examined on both naive and MPTP-exposed mice.
Meta-analysis of genetic and environmental Parkinson's disease models reveals a common role of mitochondrial protection pathways.
Specimen part, Treatment
View SamplesHuman pluripotent stem cells (hPSCs) tend to acquire chromosomal aberrations in culture, which may increase their tumorigenicity. However, the cellular mechanism(s) underlying these aberrations are largely unknown. Here we show that the DNA replication in aneuploid hPSCs is perturbed, resulting in high prevalence of defects in chromosome condensation and segregation. Global gene expression analyses in aneuploid hPSCs revealed decreased levels of actin cytoskeleton genes and their common transcription factor SRF. Down-regulation of SRF or chemical perturbation of actin cytoskeleton organization in diploid hPSCs resulted in increased replication stress and perturbation of chromosome condensation, recapitulating the findings in aneuploid hPSCs. Altogether, our results revealed that in hPSCs DNA replication stress results in a distinctive defect in chromosome condensation, underlying their ongoing chromosomal instability. Our results shed a new light on the mechanisms leading to ongoing chromosomal instability in hPSCs, and may be relevant to tumor development as well.
Genomic Instability in Human Pluripotent Stem Cells Arises from Replicative Stress and Chromosome Condensation Defects.
Specimen part, Cell line
View SamplesDue to their somatic cell origin, human induced pluripotent stem cells (HiPSCs) are assumed to carry a normal diploid genome, and adaptive chromosomal aberrations have not been fully evaluated. Here, we analyzed the chromosomal integrity of 66 HiPSC and 38 human embryonic stem cell (HESC) samples from 18 different studies by global gene expression meta-analysis. We report identification of a substantial number of cell lines carrying full and partial chromosomal aberrations, half of which were validated at the DNA level. Several aberrations resulted from culture adaptation, and others are suspected to originate from the parent somatic cell. Our classification revealed a third type of aneuploidy already evident in early passage HiPSCs, suggesting considerable selective pressure during the reprogramming process. The analysis indicated high incidence of chromosome 12 duplications, resulting in significant enrichment for cell cycle related genes. Such aneuploidy may limit the differentiation capacity and increase the tumorigenicity of HiPSCs.
Identification and classification of chromosomal aberrations in human induced pluripotent stem cells.
Specimen part, Cell line
View SamplesDue to their somatic cell origin, human induced pluripotent stem cells (HiPSCs) are assumed to carry a normal diploid genome, and adaptive chromosomal aberrations have not been fully evaluated. Here, we analyzed the chromosomal integrity of 66 HiPSC and 38 human embryonic stem cell (HESC) samples from 18 different studies by global gene expression meta-analysis. We report identification of a substantial number of cell lines carrying full and partial chromosomal aberrations, half of which were validated at the DNA level. Several aberrations resulted from culture adaptation, and others are suspected to originate from the parent somatic cell. Our classification revealed a third type of aneuploidy already evident in early passage HiPSCs, suggesting considerable selective pressure during the reprogramming process. The analysis indicated high incidence of chromosome 12 duplications, resulting in significant enrichment for cell cycle related genes. Such aneuploidy may limit the differentiation capacity and increase the tumorigenicity of HiPSCs.
Identification and classification of chromosomal aberrations in human induced pluripotent stem cells.
Specimen part, Cell line
View SamplesDue to their somatic cell origin, human induced pluripotent stem cells (HiPSCs) are assumed to carry a normal diploid genome, and adaptive chromosomal aberrations have not been fully evaluated. Here, we analyzed the chromosomal integrity of 66 HiPSC and 38 human embryonic stem cell (HESC) samples from 18 different studies by global gene expression meta-analysis. We report identification of a substantial number of cell lines carrying full and partial chromosomal aberrations, half of which were validated at the DNA level. Several aberrations resulted from culture adaptation, and others are suspected to originate from the parent somatic cell. Our classification revealed a third type of aneuploidy already evident in early passage HiPSCs, suggesting considerable selective pressure during the reprogramming process. The analysis indicated high incidence of chromosome 12 duplications, resulting in significant enrichment for cell cycle related genes. Such aneuploidy may limit the differentiation capacity and increase the tumorigenicity of HiPSCs.
Identification and classification of chromosomal aberrations in human induced pluripotent stem cells.
Specimen part, Cell line
View Samples