The identification of differentially downregulated genes in hypoxia or G9a overexpression
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE64710 | GEO | 2015/01/07
SECONDARY ACCESSION(S): PRJNA271698
REPOSITORIES: GEO
Similar Datasets
Project description:To identify that differentially downregulated genes in hypoxia or G9a overexpression, we have employed whole genome microarray expression profiling. SNU484 cells expressing GFP or GFP-G9a vector under normoxic or hypoxic conditions was used to identify that differentially downregulated genes.
2015-01-07 | E-GEOD-64710 | biostudies-arrayexpress
Project description:Epigenetic mechanisms play important roles in the regulation of tumorigenesis, and hypoxia-induced epigenetic changes may be key drivers of the adaptation of cancer cells to the hypoxic microenvironment typical of solid tumors. Previously, we showed that loss-of-function or inhibition of the oncogenic H3K9 methyltransferase G9A attenuates tumor growth and constitutes an important strategy for cancer management. However, the mechanisms by which blockade of G9A leads to a tumor suppressive effect remain poorly understood. Here, we show that G9A is highly expressed in breast cancer compared to normal breast tissue and is associated with poor prognosis in patients, where it may function as a potent oncogenic driver in this cancer type. In agreement with this, G9A inhibition leads to increased cell death, impaired cell migration, reduced cell cycle and downregulated anchorage-independent growth. Interestingly, whole transcriptome analysis revealed that a number of previously non-responsive genes become amenable to hypoxia following G9A inhibition, including many targets that drive cancer cell survival. This was accompanied by the upregulation of the hypoxia inducible factors HIF1A and HIF2A during the use of G9A inhibition to curb cancer cell growth even under normoxic conditions. Therefore, we show that G9A is a key mediator of oncogenic processes in breast cancer cells and cancer therapeutics involving G9A inhibition can be used successfully to attenuate oncogenicity. However, cancer cells mount a survival response via activation of the HIF pathway that may necessitate the additional suppression of HIF signaling for improved efficacy in the eradication of the disease.
2017-12-20 | GSE89891 | GEO
Project description:Hypoxia is one of the major driving forces mediating tumor angiogenesis, aggressiveness, as well as resistance to chemo- and radiotherapy. It has also been suggested to play important roles in stem cell maintenance for both normal and cancer tissues. However, the mechanisms by which hypoxia-driven epigenetic changes modulate tumorigenesis remain poorly understood. As the histone H3 lysine 9 (H3K9) demethylase Jmjd1a and methyltransferase G9a are upregulated downstream targets of hypoxia, we focused on these two catalytically opposing epigenetic modifiers to address this question. Through the use of homozygous Jmjd1a and G9a knockout mouse embryonic stem (ES) cells, we found that Jmjd1a was not required for stem cell self-renewal and that anti-angiogenesis related genes were epigenetically dysregulated in both Jmjd1a- and G9a deficient ES cells under hypoxic conditions, accompanied by corresponding changes in H3K9 dimethylation and H3K4 trimethylation levels in the proximal promoter regions of these target genes. Most importantly, these genetic alterations led to opposing tumor phenotypes: loss of Jmjd1a results in increased tumor growth, whereas loss of G9a produces smaller tumors. These findings provide new insights on the importance of hypoxia signalling in regulating the epigenetic status and expression of angiogenesis genes that promote tumor progression. 63 microarray samples consisting of 7 mouse ES cell lines of which 2 are wild type (control), 2 Jmjd1a knockout, 2 G9a knockout and 1 G9a knockout that was reconstituted for G9a (G9a control). Each cell line and condition was seeded at 3 different densities (2X10^5, 4X10^5 and 6X10^5) in 6 cm dishes to control for the effects of cell confluency on gene expression. 18 hours after plating, the cells were subjected to normoxia (21% O2) for 24 hours (control), normoxia 20 hours followed by hypoxia (1% O2) for 4 hours (acute hypoxia) and 24 hours hypoxia (chronic treatment). Total RNA was harvested from all samples for microarrays after the 24 hour treatments.
2014-07-30 | E-GEOD-35061 | biostudies-arrayexpress
Project description:Chronic hypoxia inhibits apoptosis to enhance survival of cancer cells. The mechanisms that prevent apoptosis under hypoxia are unclear. Here, we show that hypoxia induced G9a, a lysine methyltransferase, which methylates a tumor suppressor, Runt-related transcription factor 3 (RUNX3) at lysines 129 and 171. G9a-mediated methylation reduced transcriptional activity of RUNX3 by inhibiting interactions with its transcriptional cofactors, the core-binding factor-beta (CBF-beta) and p300, and also decreased the protein level of RUNX3 via Smurf1-mediated proteasomal degradation. Through ChIP-seq and gene expression profiling, G9a-mediated methylation inhibited expression of genes involved in apoptosis, thereby enhancing survival and proliferation of cancer cells both in vitro and vivo. Our results suggest G9a-dependent methylation of RUNX3 as a therapeutic target to control tumor growth.
2020-11-02 | GSE124481 | GEO
Project description:Chronic hypoxia inhibits apoptosis and cell cycle arrest in cancer cells, leading to cell survival, proliferation and angiogenesis. The mechanism for anti-apoptosis and cell proliferation in hypoxic cancer cells is still elusive. Here, we showed that hypoxia inactivates Runt-related transcription factor 3 (RUNX3), which is known to play as a tumor suppressor to induce apoptosis and cell cycle arrest in various cancers. RUNX3 is methylated under hypoxic conditions at lysines (K) 129 and 171 through its interaction with methyltranferase G9a. Gene expression profiling revealed that the mutations of K129 and 171 in RUNX3 induced the expression of genes related to apoptosis and cell cycle arrest under hypoxic conditions, indicating critical roles of the RNUX methylation in anti-apoptosis and cell proliferation. Moreover, K129 and 171 mutants, compared to G9a or G9a+RUNX3 control, showed significant reduction in apoptotic ability and tumor progression in xenograft models. Therefore, G9a-dependent methylation of RUNX3 is a novel target to inhibit cell proliferation and anti-apoptosis under hypoxic conditions during tumorigenesis.
2020-11-02 | GSE81693 | GEO
Project description:Hypoxia is one of the major driving forces mediating tumor angiogenesis, aggressiveness, as well as resistance to chemo- and radiotherapy. It has also been suggested to play important roles in stem cell maintenance for both normal and cancer tissues. However, the mechanisms by which hypoxia-driven epigenetic changes modulate tumorigenesis remain poorly understood. As the histone H3 lysine 9 (H3K9) demethylase Jmjd1a and methyltransferase G9a are upregulated downstream targets of hypoxia, we focused on these two catalytically opposing epigenetic modifiers to address this question. Through the use of homozygous Jmjd1a and G9a knockout mouse embryonic stem (ES) cells, we found that Jmjd1a was not required for stem cell self-renewal and that anti-angiogenesis related genes were epigenetically dysregulated in both Jmjd1a- and G9a deficient ES cells under hypoxic conditions, accompanied by corresponding changes in H3K9 dimethylation and H3K4 trimethylation levels in the proximal promoter regions of these target genes. Most importantly, these genetic alterations led to opposing tumor phenotypes: loss of Jmjd1a results in increased tumor growth, whereas loss of G9a produces smaller tumors. These findings provide new insights on the importance of hypoxia signalling in regulating the epigenetic status and expression of angiogenesis genes that promote tumor progression.
2014-07-30 | GSE35061 | GEO
Project description:G9a is the major mammalian H3-K9 methyltransferase that targets euchromatic regionsand is essential for murine embryogenesis . We demonstrate that G9a is endowed with methyltransferase activity to concomitantly repress the downstream effector Ep-CAM, thereby promoting the invasion step of the invasion-metastasis cascade. We used microarrays to detail the G9a regulated gene expression underlying invasion-metastasis cascade and identified distinct classes of up-regulated genes during this process. Lung adenocarcinoma cells with G9a knockdown or overexpression were selected for RNA extraction and hybridization on Affymetrix microarrays.
2011-12-31 | E-GEOD-22810 | biostudies-arrayexpress
Project description:G9a (EHMT2) and the G9a-like protein GLP (EHMT1) form a stable G9a/GLP heterodimer in embryonic stem cells and function cooperatively to establish and maintain the abundant repressive H3K9me2 modification, in addition to modifying several non-histone proteins. The G9a-dependent H3K9me2 is implicated in lineage-specific gene silencing and covers large chromosomal domains. While the mechanism of H3K9me2maintenance by G9a/GLP is known, how new patterns of this modification are established is not well understood. With this in mind, we used FLAG affinity purification of G9a under two different stringency conditions (150 and 300 mM NaCl) coupled with mass spectrometry to identify proteins stably associated with G9a/GLP, which could serve as potential recruiters of the complex to unmodified chromatin.
2016-03-16 | PXD003466 | Pride
Project description:G9a is the major mammalian H3-K9 methyltransferase that targets euchromatic regionsand is essential for murine embryogenesis . We demonstrate that G9a is endowed with methyltransferase activity to concomitantly repress the downstream effector Ep-CAM, thereby promoting the invasion step of the invasion-metastasis cascade. We used microarrays to detail the G9a regulated gene expression underlying invasion-metastasis cascade and identified distinct classes of up-regulated genes during this process.
2011-12-31 | GSE22810 | GEO
Project description:Background:Pulmonary arterial hypertension (PAH) is a severe condition characterized by progressive vascular remodeling of small pulmonary arteries (PAs) causing sustained elevation of PA pressure, right ventricular failure and death. Similar to cancer cells, PA smooth muscle cells (PASMCs), which play a key role in pulmonary vascular remodeling, have adopted multiple mechanisms to sustain their survival and proliferation in the presence of stress. The histone methyltransferase G9a has been shown to exert oncogenic effects and to serve as a buffer against an exaggerated transcriptional response. Therefore, we hypothesized that G9a up-regulation in PAH plays a pivotal role in pulmonary vascular remodeling by maintaining the abnormal phenotype of PAH-PASMCs. Methods: G9alevels were measured in PAs and isolated PASMCs of PAH patients and animal models. Selective G9a pharmacological inhibitors were used in human PAH-PASMCs and in rodent PAH models (i.e.Fawn-Hooded rats and Sugen/Hypoxia-exposed mice). Results: We present evidence of increased expression of G9a in PASMCs from PAH patients as well as in remodeled PAs from animal models. We found that pharmacological inhibition of G9a activity using BIX01294 and UNC0642significantly reduces the prosurvival and proproliferative potentials of cultured PAH-PASMCs. Using RNA sequencing, further exploration revealed that G9a promotes extracellular matrix production and affords protection against the negative effects of an overactive stress response. Finally, we found that therapeutic treatment with BIX01294 reduced pulmonary vascular remodeling and lowered mean PA pressure in Fawn-Hooded rats. Treatment of Sugen/hypoxia-challenged mice with BIX01294 also improved pulmonary hemodynamics and right ventricular function. Conclusions:These findings suggest that G9a inhibition may represent a new therapeutic approach in PAH.
2023-01-20 | GSE200821 | GEO