Hypoxia promotes an aggressive tumor phenotype with increased genomic instability, partially due to downregulation of DNA repair pathways. However, in addition to DNA repair, genome stability is also controlled by cell cycle checkpoints. An important issue is therefore whether hypoxia also can alter the DNA damage cell cycle checkpoints. Here, we show that hypoxia (24h 0.2% O2) alters the expression of several G2 checkpoint regulators, as examined by microarray gene expression analysis and immunoblotting of U2OS cells. While some of the changes reflected hypoxia-induced inhibition of cell cycle progression, flow cytometric bar-coding analysis of individual cells showed that the levels of several G2 checkpoint regulators were reduced in G2 phase cells after hypoxic exposure, in particular cyclin B1. These effects were accompanied by decreased Cyclin dependent kinase (CDK) activity in G2 phase cells after hypoxia. Furthermore, cells pre-exposed to hypoxia showed a longer G2 checkpoint arrest upon treatment with ionizing radiation. Similar results were found following other hypoxic conditions (~0.03 % O2 20h and 0.2% O2 72h). These results demonstrate that the DNA damage G2 checkpoint can be altered as a consequence of hypoxia, and we propose that such alterations may influence the genome stability of hypoxic tumors.
Hypoxia-induced alterations of G2 checkpoint regulators.
Specimen part, Cell line
View SamplesWe explored the prognostic impact of the dynamic contrast enhanced MR imaging (DCE-MRI) parameter ABrix in cervical cancer combined with global gene expression data to reveal the underlying molecular phenotype of the parameter and construct a gene signature that reflected ABrix. Based on 78 cervical cancer patients subjected to curative chemoradiotherapy, we identified a prognostic ABrix parameter by pharmacokinetic analysis of DCE-MR images based on the Brix model, where tumors with low ABrix appeared to be most aggressive. Gene set enrichment analysis of 46 tumors with pairwise DCE-MRI and gene expression data showed a significant correlation between ABrix and the hypoxia gene sets, whereas gene sets related to proliferation, radioresistance, and wound healing were not significant. Hypoxia gene sets specific for cervical cancer created in cell culture experiments, including targets of the hypoxia inducible factor (HIF1) and the unfolded protein response (UPR), were the most significant. In the remaining 32 tumors, low ABrix was associated with upregulation of HIF1 protein expression, as assessed by immunohistochemistry, consistent with increased hypoxia. Based on the hypoxia gene sets, a signature of 31 genes that were upregulated in tumors with low ABrix was constructed. This DCE-MRI hypoxia gene signature showed prognostic impact in an independent validation cohort of 109 patients.
Hypoxia-induced gene expression in chemoradioresistant cervical cancer revealed by dynamic contrast-enhanced MRI.
Specimen part, Cell line, Treatment
View SamplesThis study was undertaken in order to characterize the functions of Rex-1 and identify potential Rex-1 target genes.Both alleles of the Rex-1 gene were disrupted in J1 mouse embryonic stem cells. Gene expression levels in one of the resulting Rex-1 knockout cell lines was compared to that of J1 wild type cells.
Analysis of Rex1 (zfp42) function in embryonic stem cell differentiation.
No sample metadata fields
View SamplesMale Sprague-dawley rats were exposed to saline, isopropyl alcohol, 1mg/kg, 3mg/kg or 6 mg/kg sulfur mustard for 30 min, 1 hr, 3 hr, 6 hr, or 24 hr before analysis of lung tissue by oligonucleotide array analysis.
Genomic analysis of rodent pulmonary tissue following bis-(2-chloroethyl) sulfide exposure.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Cloning and variation of ground state intestinal stem cells.
Specimen part, Treatment
View SamplesWe performed an RNA Sequencing experiment on dorsal hippocampal tissue from four groups of animals: Baf53b+/- homecage (Baf53b+/- HC); Baf53b+/- behavior (Baf53b+/- Beh); wildtype homecage (WT HC); and wildtype behavior (WT Beh). Homecage animals were sacrificed directly from the animal's cage. Behavior animals were sacrificed thirty minutes following Object Location Memory training. The objective of this study was to examine activity regulated gene expression following a learning event (HC vs Beh) in wildtype and Baf53b+/- mutant mice. Overall design: Examination of gene expression following a learning event in wildtype and Baf53b+/- mutant mice in dorsal hippocampus.
The neuron-specific chromatin regulatory subunit BAF53b is necessary for synaptic plasticity and memory.
Specimen part
View SamplesDespite major advances with embryonic and induced pluripotent stem cells or lineage-committed, p63-expressing stem cells of stratified epithelia, we know less about the indigenous stem cells of the gastrointestinal tract, pancreas, liver, and other columnar epithelia which collectively resist cloning in their elemental states. Here we demonstrate the cloning of highly immature epithelial stem cells from defined regions of the human intestine and colon. We show that single cell-derived pedigrees can be propagated indefinitely while often sustaining minimal copy number and sequence variation. Despite prolonged cultivation, these pedigrees from disparate regions of the intestinal tract respond to identical differentiation signals by formation of epithelia with eponymous structural and gene expression features. These data suggest developmental patterning of cell-autonomous commitment programs in stem cells that enforce specialization along the gastrointestinal tract and predict the utility of these cells in disease modeling and regenerative medicine.
Cloning and variation of ground state intestinal stem cells.
Specimen part
View SamplesClostridium difficile (Cd) is a gram-positive, spore-forming bacterium and the primary cause of nosocomial diarrhea and pseudomembranous colitis. The pathogenicity of Cd has been linked to its production of TcdA and TcdB. While they cause fluid secretion, inflammation, and colonic damage, their respective and synergistic roles have been difficult to ascertain. In infection animal model, TcdB has been demonstrated to be a key virulence factor, and TcdB causes obvious damage in human and porcine colonic explants. Using the colonic epithelia derived from cloned colonic stem cells, we have developed a model to test the response to TcdB. Epithelia generated in air-liquid interface cultures from cloned transverse colon stem cells were challenged with TcdB at different concentrations and durations.
Cloning and variation of ground state intestinal stem cells.
Specimen part, Treatment
View SamplesDespite major advances with embryonic and induced pluripotent stem cells or lineage-committed, p63-expressing stem cells of stratified epithelia, we know less about the indigenous stem cells of the gastrointestinal tract, pancreas, liver, and other columnar epithelia which collectively resist cloning in their elemental states. Here we demonstrate the cloning of highly immature epithelial stem cells from defined regions of the human intestine and colon. In this study, we have isolated ileal stem cells and performed air-liquid interface method to induce differentiation of human ileal stem cells. The differentiated structure showed villi-like epithelia which contains enterocytes, goblet cells, endocrine cells and paneth cells.
Cloning and variation of ground state intestinal stem cells.
Specimen part
View SamplesThe instrinsic regenerative capacity of human fetal cardiac mesenchymal stromal cells (MSCs) has not been fully characterised. Here we demonstrate that we can expand cells with characteristics of cardiovascular progenitor cells from the MSC population of human fetal hearts with only minor fluctuations over time in culture (from day 15 to day 48).
Wnt/β-Catenin Stimulation and Laminins Support Cardiovascular Cell Progenitor Expansion from Human Fetal Cardiac Mesenchymal Stromal Cells.
No sample metadata fields
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