Transcriptional differences in breast cancer cells exposed to acute versus chronic hypoxia.
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE240211 | GEO | 2023/09/01
REPOSITORIES: GEO
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Project description:To determine hypoxia mediated changes in whole blood, normal C57Bl/10 mice were gradually exposed to a chronic hypoxic environment, equivalent to an altitude of 6500m, for 2 weeks in vivo. Control, age-matched mice were maintained under normoxic, normobaric conditions by exposing them to ambient air in Philadelphia (c. 50 mts above sea level). Purpose: To determine the expression profile of genes differentially expressed in mouse whole blood upon exposure to normobaric hypoxia in vivo. Methods: The hypoxic group consisting of 6 C57/BL10 mice was exposed to normobaric hypoxia, in a specially designed and hermetically closed hypoxic chamber, using a gas mixing system Pegas 4000 MF (Columbus Instruments, Ohio, USA). The oxygen level was decreased from 21% to 8% over a period of 14 days. 6 control mice were kept at normal oxygen and pressure levels by exposing them to ambient air in Philadelphia (c. 50 mts above sea level). RNA from whole blood was isolated, processed and used for microarray-based expression profiling. Profiles were generated for genes differentially expressed at control versus normobaric hypoxia in whole blood using a false discovery rate (FDR) of 0%. The Profile was validated by real-time quantitative reverse transcription-polymerase chain reaction (qPCR) on 2 biologically independent samples, not used for generating the profile. Results: The transcriptomes associated with normobaric hypoxia in whole blood were identified. We found 4723 genes that were differentially expressed in normobaric hypoxic whole blood compared to control with a 0% FDR and a 2 fold cutoff. Conclusion: Transcriptome level differences exist in the whole blood of animals subjected to normobaric hypoxia. Our definition of the normobaric hypoxia blood transcriptome provides insight into the functioning and response to hypoxia in whole blood.
2010-05-07 | E-GEOD-15894 | biostudies-arrayexpress
Project description:Intratumoral hypoxia causes the formation of dysfunctional blood vessels which contribute to tumor metastasis. Blood vessels are embedded in the tumor stroma where cancer-associated fibroblasts (CAFs) constitute the most prominent cellular component. We found that hypoxic human mammary CAFs promote blood vessel growth in CAF-endothelial cell co-cultures in vitro. Mass spectrometry-based proteomic analysis of CAF secretome unravels how hypoxic CAFs contribute to blood vessel abnormalities by altering the secretion of a multitude of pro- and anti-angiogenic factors. Hypoxia induces pronounced remodeling of the CAF proteome, including proteins that have not been previously related to this process. Our study provides a map of unprecedented depth of hypoxia-induced molecular alterations in mammary CAFs that can be exploited to identify novel mechanisms that control hypoxic CAF functions.
2019-02-15 | PXD006535 | Pride
Project description:Hypoxia is an important driver of cancer progression, and rapidly growing tumors often result in intratumoral hypoxic regions. Hypoxia is associated with metabolic reprogramming and angiogenesis, resulting in enhanced tumor progression. Here, we aimed to study breast cancer hypoxia responses at the proteomic level, and we wanted to identify differences in protein secretion from luminal-like and basal-like cell lines before and after hypoxia.
2023-06-23 | PXD027136 | Pride
Project description:Vascular disruption following bony injury results in a hypoxic gradient within the wound microenvironment. Nevertheless, the effects of low oxygen tension on osteogenic precursors remain to be fully elucidated. In the present study, we investigated in vitro osteoblast and mesenchymal stem cell differentiation following exposure to 21% O(2) (ambient oxygen), 2% O(2) (hypoxia), and <0.02% O(2) (anoxia). Hypoxia had little effect on osteogenic differentiation. In contrast, short-term anoxic treatment of primary osteoblasts and mesenchymal precursors inhibited in vitro bone nodule formation and extracellular calcium deposition. Cell viability assays revealed that this effect was not caused by immediate or delayed cell death. Microarray profiling implicated down-regulation of the key osteogenic transcription factor Runx2 as a potential mechanism for the anoxic inhibition of differentiation. Subsequent analysis revealed not only a short-term differential regulation of Runx2 and its targets by anoxia and hypoxia, but a long-term inhibition of Runx2 transcriptional and protein levels after only 12-24 h of anoxic insult. Furthermore, we present evidence that Runx2 inhibition may, at least in part, be because of anoxic repression of BMP2, and that restoring Runx2 levels during anoxia by pretreatment with recombinant BMP2 rescued the anoxic inhibition of differentiation. Taken together, our findings indicate that brief exposure to anoxia (but not 2% hypoxia) down-regulated BMP2 and Runx2 expression, thus inhibiting critical steps in the osteogenic differentiation of pluripotent mesenchymal precursors and committed osteoblasts. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Computed
2005-07-16 | E-GEOD-2951 | biostudies-arrayexpress
Project description:Validation of an in vitro model of hypoxia using a primary cell culture of mouse embryonic fibroblasts (MEF) exposed to 1% oxygen at 37 degrees celsius. Control cells were exposed to atmospheric oxygen. Hypoxic and normoxic MEF (in 100 mm dishes, four replicates per group) were submitted to gene expression analysis using Affymetrix Exon microarrays. Differential gene expression analysis was performed with R package DEMI (http://biit.cs.ut.ee/demi/).
2014-03-01 | E-GEOD-54228 | biostudies-arrayexpress
Project description:Intratumoral hypoxia causes the formation of dysfunctional blood vessels which contribute to tumor metastasis. Blood vessels are embedded in the tumor stroma where cancer-associated fibroblasts (CAFs) constitute the most prominent cellular component. We found that hypoxic human mammary CAFs promote blood vessel growth in CAF-endothelial cell co-cultures in vitro. Mass spectrometry-based proteomic analysis of CAF secretome unravels how hypoxic CAFs contribute to blood vessel abnormalities by altering the secretion of a multitude of pro- and anti-angiogenic factors. Hypoxia induces pronounced remodeling of the CAF proteome, including proteins that have not been previously related to this process. Amongst those, the uncharacterized antisense gene protein NCBP2-AS2 is one of the most transcriptionally upregulated proteins in the proteome and secretome of hypoxic CAFs. Silencing of NCBP2-AS2 abrogates the pro-angiogenic function acquired by hypoxic CAFs through decreasing VEGF expression levels to the levels found in normoxic CAFs.
2019-02-15 | PXD006539 | Pride
Project description:The environment inside even a small tumor is characterized by total (anoxia) or partial oxygen deprivation, hypoxia. It has been shown that radiotherapy and some conventional chemotherapies may be less effective in hypoxia, and therefore it is important to investigate how different drugs act in different microenvironments. In the associated study we performed a large screening of the effects of 19 clinically used or experimental chemotherapeutic drugs on four different cell lines in conditions of normoxia, hypoxia and anoxia. A panel of 19 commercially available drugs: 5-fluorouracil, acriflavine, bortezomib, cisplatin, digitoxin, digoxin, docetaxel, doxorubicin, etoposide, gemcitabine, irinotecan, melphalan, mitomycin c, rapamycin, sorafenib, thalidomide, tirapazamine, topotecan and vincristine were tested for cytotoxic activity on the cancer cell lines A2780 (ovarian), ACHN (renal), MCF-7 (breast), H69 (SCLC) and U-937 (lymphoma). Parallel aliquots of the cells were grown at different oxygen pressures and after 72 hours of drug exposure viability was measured with the fluorometric microculture cytotoxicity assay (FMCA). Sorafenib, irinotecan and docetaxel were in general more effective in an oxygenated environment, while cisplatin, mitomycin c and tirapazamine were more effective in a low oxygen environment. Surprisingly, hypoxia in H69 and MCF-7 cells mostly rendered higher drug sensitivity. In contrast ACHN appeared more sensitive to hypoxia, giving slower proliferating cells, and consequently, was more resistant to most drugs. Gene expression analysis was performed on MCF-7 cells after 90 hours in either anoxic or hypoxic conditions, and compared to cells grown in a regular cell incubator. The gene expression analysis was performed to validate that the cells were hypoxic/anoxic and showed the characteristic hypoxia response. Microarray based mRNA profiling was used to charactarize cells grown in hypoxia and anoxia. In the associated study we performed a large screening of the effects of 19 clinically used or experimental chemotherapeutic drugs on four different cell lines in conditions of normoxia, hypoxia and anoxia. We fin that hypoxia/anoxia render cancer cells both more resistant and more sensistive, depending of the type of drug used. The gene expression analysis was performed to validate that the cells really were hypoxic/anoxic and showed the characteristic hypoxia response. The cell line used for the gene expression analysis was MCF-7.
2014-05-04 | E-GEOD-47009 | biostudies-arrayexpress
Project description:How cancer cells adapt to hypoxia during tumor development remains an important question. The hypothesis tested in the present study was that tumor cell-derived exosome vesicles (also known as microvesicles or extracellular vesicles) are mediators of hypoxia-dependent intercellular signaling in glioblastoma (GBM), i.e. highly aggressive brain tumors characterized by hypoxia and a vascular density that is among the highest of all human malignancies. In vitro hypoxia experiments and studies with patient materials reveal the enrichment in exosomes of hypoxia-regulated mRNAs and proteins, several of which were associated with poor patient prognosis. We show that cancer cell exosomes mediate hypoxia-dependent, phenotypic modulation of stromal cells in vitro and ex vivo, resulting in accelerated GBM tumor angiogenesis and growth in mice. These data suggest that exosomes constitute potent mediators of hypoxia-driven tumor development, and circulating multiparameter biomarkers of tumor hypoxia. U87 MG glioblastoma cells were grown at normoxic (21% oxygen) or hypoxic (1% oxygen) conditions for 48 hours. Conditioned media from normoxic and hypoxic cells were then used to isolate exosomes by differential centrifugation. Both cells and exosomes were lysed in Trizol reagent, and RNA was isolated.Total RNA from all samples (four types of samples in three biological repilicates) was subjected to genome-wide transcriptional analysis with Illumina HumanHT-12 V3.0 expression beadchip. Gene expression profile obtained from hypoxic U87 MG glioblastoma cells was compared to the profile of normoxic control cells. Analogically, gene expression profile obtained from hypoxic U87 MG cells was compared to the profile of exosomes secreted by normoxic U87 MG cells.
2013-03-20 | E-GEOD-45301 | biostudies-arrayexpress
Project description:Hypermethylation of tumor suppressor gene (TSG) promoters confers growth advantages to cancer cells, but how these changes arise is poorly understood. Here, we report that tumor hypoxia reduces the activity of oxygen-dependent TET enzymes, which catalyze DNA de-methylation through 5-methylcytosine oxidation. This occurs independently of hypoxia-associated alterations in TET gene expression, basal metabolism, HIF activity or nuclear reactive oxygen species, but directly depends on oxygen shortage. Hypoxia-induced loss of TET activity increases hypermethylation at gene promoters in vitro, while also in patients, gene promoters are markedly more methylated in hypoxic than normoxic tumors. Affected genes are frequently involved in DNA repair, cell cycle regulation, angiogenesis and metastasis, indicating cellular selection of hypermethylation events. Overall, up to 50% of the tumor-associated hypermethylation is ascribable to hypoxia across various cancer types. Accordingly, spontaneous murine breast tumors become hypermethylated when rendered hypoxic through vessel pruning, whereas vessel normalisation rescues this effect. Tumor hypoxia thus acts as a novel regulator underlying DNA methylation.
2016-09-01 | GSE71402 | GEO
Project description:Hypermethylation of tumor suppressor gene (TSG) promoters confers growth advantages to cancer cells, but how these changes arise is poorly understood. Here, we report that tumor hypoxia reduces the activity of oxygen-dependent TET enzymes, which catalyze DNA de-methylation through 5-methylcytosine oxidation. This occurs independently of hypoxia-associated alterations in TET gene expression, basal metabolism, HIF activity or nuclear reactive oxygen species, but directly depends on oxygen shortage. Hypoxia-induced loss of TET activity increases hypermethylation at gene promoters in vitro, while also in patients, gene promoters are markedly more methylated in hypoxic than normoxic tumors. Affected genes are frequently involved in DNA repair, cell cycle regulation, angiogenesis and metastasis, indicating cellular selection of hypermethylation events. Overall, up to 50% of the tumor-associated hypermethylation is ascribable to hypoxia across various cancer types. Accordingly, spontaneous murine breast tumors become hypermethylated when rendered hypoxic through vessel pruning, whereas vessel normalisation rescues this effect. Tumor hypoxia thus acts as a novel regulator underlying DNA methylation.
2016-09-01 | GSE71401 | GEO