Tumor hypoxia causes DNA hypermethylation by reducing TET activity
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus Homo sapiens
PROVIDER: GSE71403 | GEO | 2016/09/01
SECONDARY ACCESSION(S): PRJNA291096
REPOSITORIES: GEO
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Project description:Genome wide DNA methylation profiling of normoxic and hypoxic non-small-cell lung cancer samples for 5mC and 5hmC. The Illumina Infinium 450k Human DNA methylation Beadchip v1.2 was used to obtain DNA methylation and hydroxymethylation profiles across 485,512 CpGs from DNA extracted from fresh-frozen tumor samples. Samples included 12 hypoxic and 12 normoxic tumor samples, with hypoxia determined according to the hypoxia metagene score (Buffa et al, Br J Cancer 2010). To profile hydroxymethylation, 5hmC was glycosylated and 5mC was oxidised as described by Yu and colleagues (Nat Protoc 2012), and hydroxymethylation and methylation were differentially profiled according to the Nazor and colleagues (Genomics 2014). 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 | GSE71398 | GEO
Project description: Not available
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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 | GSE71399 | 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
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 | GSE71400 | GEO
Project description:Tumor hypoxia causes DNA hypermethylation by reducing TET activity
| PRJNA291096 | ENA
Project description:Hypoxia, a hallmark of most solid tumors, leads to aberrations in epigenetic modifications promoting malignant tumor phenotypes, including metastatic features and stem cell-like characteristics. Aberrant DNA methylation has been considered to play an essential role during tumor progression and tightly associate with tumor malignancy. However, the mechanism by which hypoxia alters DNA methylation to promote tumor malignancy remains poorly understood. Ten-eleven translocation 1-3 (TET1-3) proteins, which catalyze the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), play a critical role in the DNA demethylation that controls different biological processes. Here we demonstrate that the expression of TET1 and TET3 is closely associated with tumor hypoxia, tumor malignancy and poor prognosis of patients with breast cancer. Hypoxia results in deregulation of TET1 and TET3, leading to breast tumor initiating cell (BTIC) properties. Mechanically, hypoxia regulates expression of TET1 and TET3 via hypoxia-inducible factor-1a (HIF-1a), thereby resulting in 5hmC genome-wide changes, which in turn leads to the upregulation of TNFa expression and activation of its downstream p38-MAPK pathway. Importantly, signal transduction through the TET-TNFa-p38-MAPK signaling axis is required for the acquisition of BTIC characteristics and chemotherapy resistance, leading to more malignant tumor phenotypes. Inhibition of the hypoxia-TET-TNFα-p38-MAPK signaling pathway results in compromised BTIC properties and tumorigenicity in vitro and in vivo, suggesting a possible therapeutic strategy.
2015-10-05 | GSE60434 | GEO
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