Unknown,Transcriptomics,Genomics,Proteomics

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Genome-wide methylation analysis of prostate tissues reveals global methylation patterns of prostate cancer

ABSTRACT: High-throughput analyses of concordant gene methylation and expression events were carried out for 91 human prostate specimens, including prostate cancer (T), matched normal adjacent to tumor (AT), and organ donor (OD). Methylated DNA in genomic DNA was immunoprecipitated with anti-methylcytidine antibodies and detected by Affymetrix human whole genome SNP 6.0 chips. Methylated genomic DNA was purified by 5-hmc antibodies and Affymetrix SNP arrays were performed according to the manufacturer's manual. Copy number analysis of Affymetrix human SNP arrays was performed for both 5mc- and genomic DNA of prostate cancer samples. Methylations of genes were called when the allel amplification was reported in 5_mc DNA, and the background of the detection was suppressed by matched DNA sample. we used copy number of each probe set as baseline to detect the enrichment of methylated DNA from the same sample. Therefore, each specimen has two arrays; one is straight copy number (*SNP.CEL), another methylation enriched DNA (*5MC_SNP.CEL). Each CNV probe is based on the design from Affymetrix but no SNP ID was assigned.

ORGANISM(S): Homo sapiens

SUBMITTER: Yan P. Yu

PROVIDER: E-GEOD-45000 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Beginning with precursor lesions, aberrant DNA methylation marks the entire spectrum of prostate cancer progression. We mapped the global DNA methylation patterns in prostate tissues (n=17) and cells (n=2) from fifty nanograms of genomic DNA using Methylplex-Next Generation Sequencing (M-NGS). A Hidden Markov Model (HMM)-based algorithm previously used for Chip-Seq data analysis(http://www.sph.umich.edu/csg/qin/HPeak) was used to locate peaks from mapped reads obtained in each sequencing run. The total methylation events in intergenic/intronic regions between benign adjacent and cancer tissues were comparable. While approximately 20% of all CpG islands (CGIs) (68,508) were methylated in tissues, promoter CGI methylation gradually increased from ~12.6% in benign samples to 19.3% and 21.8% in localized and metastatic cancer tissues. We found distinct patterns in promoter methylation around transcription start sites, where methylation occurred directly on the CGIs, flanking regions and on CGI sparse promoters. Among the 6,691 methylated promoters in prostate tissues, 2481 differentially methylated regions (DMRs) are cancer specific and several previously studied targets were among them. A novel cancer specific DMR in WFDC2 promoter showed 77% methylation in cancer (17/22), 100% methylation in transformed prostate cell lines (6/6), none in the benign tissues (0/10) and normal PrEC cells. Integration of LNCaP DNA methylation and H3K4me3 data suggested a role for DNA methylation in alternate transcription start site utilization. While methylated promoters containing CGIs had mutually exclusive H3K4me3 modification, the histone mark was absent in CGI sparse promoters. Finally, we observed difference in methylation of LINE-1 elements between transcription factor ERG positive and negative cancers. The comprehensive methylome map presented here will further our understanding of epigenetic regulation of the prostate cancer genome. We mapped the global DNA methylation patterns in prostate tissues (n=17; data not available in GEO - being deposited in dbGaP for controlled access) and cells (n=2) from fifty nanograms of genomic DNA using Methylplex-Next Generation Sequencing (M-NGS). For replicate analysis in cell lines, a total of 4 runs were completed for PrEC prostate normal cell line, and 5 runs were completed for LNCaP prostate cancer cell line. For tissue samples, 2 benign prostate samples were ran twice on illumina next generation sequencing platform to access overall repeatability of M-NGS.

Project description:TMPRSS2-ERG gene fusions that are frequently identified in prostate cancer can be generated either through chromosomal translocation or via interstitial deletion. The latter mechanism deletes an interstitial region of ~3Mb and it remains largely unanswered whether genes deleted within this region contribute to prostate cancer. By characterizing two knockin mouse models recapitulating TMPRSS2-ERG fusions with or without the interstitial deletion, we found that only those with deletion developed poorly differentiated adenocarcinomas with epithelial-to-mesenchymal transition, when under a Pten-null background. We identified several interstitial genes, including ETS2 and BACE2, whose reduced expression correlates with worse disease-free survival and lethal disease. By using an Ets2 conditional knockout allele, we demonstrated that loss of one copy of Ets2 was sufficient for prostate cancer progression when under a Pten-null background. Collectively, our data suggest that ETS2 is a prostate tumor suppressor and haploinsufficiency of one or more interstitial genes contributes to prostate cancer progression. Genotyped male mice were euthanized at 12 months of age and prostates isolated. Prostates were fixed overnight in 10% formalin and stored in 70% ethanol until tissue processing and paraffin embedding. Serial sections were cut from paraffin blocks which were stained for H&E and analyzed by a trained rodent histopathologist. Using these sections as a visual guide for specific types of lesions, the sequential sections were stained with hematoxylin and used for laser capture microdissection on ArcturusXT system. Epithelial cells within notable high grade prostate intraepithelial neoplasia (HG-PIN) lesions were microdissected from 3 mice from each corresponding genotype. In addition, poorly differentiated adenocarcinomas from PbCre;T-3Mb-Erg/+;PtenL/L mice were also dissected. RNA was isolated from the microdissected tissue using the Qiagen RNeasy FFPE kit and subjected to Nugen Amplification before microarray analysis on an Affymetrix Mouse Gene 2.0 ST chip.

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Genome-wide methylation analysis of prostate tissues reveals global methylation patterns of prostate cancer

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