Genome-wide methylation in paired lung tumor/non-tumor samples using the HELP assay
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE35520 | GEO | 2012/04/01
SECONDARY ACCESSION(S): PRJNA152239
REPOSITORIES: GEO
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Project description:In lung cancer, hypermethylation of specific gene promoters has been found during the progressive carcinogenesis. The identification of common methylation events will aid in the understanding of molecular events during neoplastic transformation and help develop biomarkers for cancer with high predictive and diagnostic value. To explore common methylation events on a genome-wide scale in lung cancer, we analyzed the methylation profiles of paired NSCLC tumor and far adjacent non-tumor samples using the HELP-microarray assay, which yields information on 1.2 million fragments throughout the genome. In this study, 24 pairs of tumor and adjacent non-tumor samples were analyzed using the HELP assay. At p = 5E-6, we identified 26,138 differentially methylated fragments (corresponding to 2 CpG sites each) in tumor versus non-tumor. The overall trend was consistent with genome-wide hypomethylation and locus specific hypermethylation (localized to CG-island containing promoters). We could identify both known and novel regions of the genome as well as specific gene-promoters that are hypermethylated in tumor versus non-tumor. The HELPassay: HpaII tiny fragment enrichment by ligation-mediated polymerase chain reaction [PCR] assay 24 pairs of NSCLC subjects, tumor and paired non-tumor samples from each subject were analyzed. Individual HpaII restriction digest profiles were compared to an internal MspI digest control, to yield differentially methylated fragments for every sample. Samples were compared intra-subject between tumor and adjacent non-tumor for these differential methylation profiles and the overall significant changes across 24 subjects were identified.
2012-03-31 | E-GEOD-35520 | biostudies-arrayexpress
Project description:Genome-wide methylation in paired lung tumor/non-tumor samples using the HELP assay
| PRJNA152239 | ENA
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: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
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: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:A large-scale characterization of the methylation states of candidate CpG islands (CGIs) throughout the gastric cancer methylome has not previously been conducted. Genome-wide DNA methylation profiles were compared between 4 metastatic and 4 non-metastatic gastric carcinomas (GCs) and their surgical margins (SMs). The GC genome showed significantly higher proportions of hypomethylation in the promoter and exon-1 regions, as well as increased hypermethylation of intragenic fragments when compared to SMs. Differential methylation was observed in CGIs near transcription start sites of 546 genes between GCs and SMs, and 601 genes between metastatic and non-metastatic GCs. From the list of differentially methylated CGIs, 68 candidate genes and 10 known tumor-related genes were selected for further characterization based on their known molecular function using DHPLC. Significant differential methylation was validated in the CGIs of 15 genes between GCs and SMs (Ps<0.05) and confirmed using bisulfite-sequencing. These genes include BMP3, BNIP3, CDKN2A, ECEL1, ELK1, GFRA1, HOXD10, KCNH1, PSMD10, PTPRT, SIGIRR, SRF, TBX5, TFPI2, and ZNF382. Hypomethylation of CGIs correlated with up-regulation of GFRA1 expression in GCs, while hypermethylation of other genes inactivated their transcription. Most importantly, prevalence of GFRA1, SRF, and ZNF382 methylation alterations were inversely and coordinately associated with GC metastasis and the patients’ overall survival throughout discovery and testing cohorts in China as well as independent validation cohorts in Japan and Korea. In conclusion, methylation changes in the CGIs of 15 genes correlated strongly with GC development. GFRA1 hypomethylation and SRF and ZNF382 hypermethylation are potential synergistic biomarkers for the prediction of GC metastasis. To identify differential methylation of CGIs related to GC development and metastasis, genome-wide DNA methylation changes in 8 pairs of GC and SM samples were analysed using the MCAM assay with a 99K custom-designed Agilent oligonucleotide microarray composed of 99,027 probes targeting 6,177 unique protein-coding genes containing at least two methylation-sensitive/insensitive SmaI/ XmaI restriction sites (CCC|GGG/ C|CmCGGG) as described in Shen et al, PLoS Genet 3, 2023-2036 (2007).
2014-06-02 | E-GEOD-47724 | biostudies-arrayexpress
Project description:Promoter hypermethylation divides colon cancers into subtypes with and without a CpG island methylator phenotype (CIMP). Here, we performed genome-wide DNA methylation profiling of colonic normal and tumor tissues to dissect development of CpG hypermethylation in colon carcinogenesis. This identified age-environment related versus genetically driven CpG hypermethylation, the latter being associated with CIMP cancers. We found a strong association between BRAFV600E mutation and downregulation of the DNA demethylases TET1 and TET2. Expression of BRAFV600E in CIMP cancer cells suppressed TET1 transcription, which was sufficient to establish hypermethylation at CIMP genes promoters, including that of TET2. This phenotype was reverted by the BRAFV600E inhibitor vemurafenib. Thus, BRAFV600E, via impairment of cytosine de-methylation, is a genetic driver of CIMP in colon tumorigenesis. Genome-wide DNA methylation profiling of adjacent non-tumor colon tissue and colon adenocarcinoma samples. The Illumina Infinium 27k Human DNA methylation Beadchip v1.2 was used to obtain DNA methylation profiles across approximately 27,000 CpGs. Samples included 8 colon cancer tissues and their associated healthy mucosa (CAM).
2019-12-18 | GSE98531 | GEO
Project description:Global loss of DNA methylation and locus/gene-specific gain of DNA methylation are two distinct hallmarks of carcinogenesis. Aberrant DNA methylation is implicated in smoking-related lung cancer. In this study, we have comprehensively investigated the modulation of DNA methylation consequent to chronic exposure to a prototype smoke-derived carcinogen, benzo[a]pyrene diol epoxide (B[a]PDE), in genomic regions of significance in lung cancer, in normal human cells. We have used a pulldown assay for enrichment of the CpG methylated fraction of cellular DNA combined with microarray platforms, followed by extensive validation through conventional bisulfite-based analysis. Here, we demonstrate strikingly similar patterns of DNA methylation in non-transformed B[a]PDE-treated cells vs control using high-throughput microarray-based DNA methylation profiling confirmed by conventional bisulfite-based DNA methylation analysis. The absence of aberrant DNA methylation in our model system within a timeframe that precedes cellular transformation suggests that following carcinogen exposure, other as yet unknown factors (secondary to carcinogen treatment) may help initiate global loss of DNA methylation and region-specific gain of DNA methylation, which can, in turn, contribute to lung cancer development. Unveiling the initiating events that cause aberrant DNA methylation in lung cancer has tremendous public health relevance, as it can help define future strategies for early detection and prevention of this highly lethal disease. Methylated fragments in genomic DNA extracted from benzo[a]pyrene diol epoxide (B[a]PDE)-treated normal human fibroblasts versus control (solvent [dimethylsulfoxide (DMSO)-treated counterpart cells] were enriched with the MIRA assay and hybridized together with input genomic DNA to NimbleGen's whole genome tiling array.
2010-04-29 | E-GEOD-21532 | biostudies-arrayexpress