Project description:Epigenetic reprogramming is commonly observed in cancer, and is hypothesized to involve multiple mechanisms, including DNA methylation and Polycomb repressive complexes (PRCs). Here we devise a new experimental and analytical strategy using customized high density tiling arrays to investigate coordinated patterns of gene expression, DNA methylation and Polycomb marks which differentiate prostate cancer cells from their normal counterparts. Three major changes in the epigenomic landscape distinguish the two cell types. Developmentally significant genes containing CpG islands which are silenced by PRCs in the normal cells acquire DNA methylation silencing and lose their PRC marks (epigenetic switching). Since these genes are normally silent this switch does not cause de novo repression but might significantly reduce epigenetic plasticity. Two other groups of genes are silenced by either de novo DNA methylation without PRC occupancy (5mC reprogramming) or by de novo PRC occupancy without DNA methylation (PRC reprogramming). Our data suggest that the two silencing mechanisms act in parallel to reprogram the cancer epigenome, and that DNA hypermethylation may replace Polycomb based repression near key regulatory genes, possibly reducing their regulatory plasticity. Profiling 5mC and H3K27m3/Suz12 occupancy in the PC3 cancer line and the PrEC system. Hybridization over a custom array including a representative set of promoters (-2.5 to +1 kb) with variable CpG content levels and variable expression levels in the two cell systems.
Project description:Epigenetic reprogramming is commonly observed in cancer, and is hypothesized to involve multiple mechanisms, including DNA methylation and Polycomb repressive complexes (PRCs). Here we devise a new experimental and analytical strategy using customized high density tiling arrays to investigate coordinated patterns of gene expression, DNA methylation and Polycomb marks which differentiate prostate cancer cells from their normal counterparts. Three major changes in the epigenomic landscape distinguish the two cell types. Developmentally significant genes containing CpG islands which are silenced by PRCs in the normal cells acquire DNA methylation silencing and lose their PRC marks (epigenetic switching). Since these genes are normally silent this switch does not cause de novo repression but might significantly reduce epigenetic plasticity. Two other groups of genes are silenced by either de novo DNA methylation without PRC occupancy (5mC reprogramming) or by de novo PRC occupancy without DNA methylation (PRC reprogramming). Our data suggest that the two silencing mechanisms act in parallel to reprogram the cancer epigenome, and that DNA hypermethylation may replace Polycomb based repression near key regulatory genes, possibly reducing their regulatory plasticity.
Project description:Genome-wide DNA methylation profiling of human PC3 invasive prostate cancer cell line treated with vehicle control (SAH, S-adenosylhomocysteine) and with SAM (S-adenosylmethionine) as well as of untreated human LNCaP non-invasive prostate cancer cell line. The Illumina Infinium 450k Human DNA Methylation BeadChip v1.2 was used to obtain DNA methylation profiles across approximately 450,000 CpGs in human cell lines exposed to described treatments. Samples included biological triplicate of PC3 control (SAH treated), biological triplicate of PC3 treated with SAM, and biological duplicate of LNCaP untreated.
Project description:Aberrant DNA hypermethylation of CpG island (CGI) promoters are associated with transcriptional repression of many tumor suppressor genes and lead to tumor progression in many cancers. Most recently, one research group observed that aberrantly hypermethylated genes in multiple cancers are already repressed, but their promoters are maintained in a hypomethylated state in pre-cancerous tissues.Their studies didn't provide a clue to explain by what mechanisms those genes were repressed in pre-cancerous tissues. Another research group found that many genes with de novo promoter hypermethylation in colon cancer were among the subset of genes "bivalently" marked in embryonic stem cells and adult stem/progenitor cells by repressive Polycomb group proteins (PcG), which are known for maintaining low, but poised, transcription.These observations provide a clue that CGI promoter hypermethylation in cancers is associated with PcG target genes in pre-cancerous tissues.we took advantage of ChIP-BS-seq technology and applied it to examine H3K27me3 and H3K4me3 profiles for one normal lymphoblastoid cell line (YH) and three cancer cell lines including one cervical cancer cell line (Hela) and two gastric cancer (GC) cell lines (BGC-823 and AGS). We aplied ChIP-BS technology to examine H3K27me3 marks, which are catalyzed by the SET domain histone methyltransferase EZH2 and have a repressive function with 50bp pair-end sequencing. found H3K27me3 marks were enriched preferentially at CpG islands, (+/-500) transcription start sites (TSSs) and exons in two GC cell lines (BGC-823 and AGS). In YH cells, H3K27me3 marks were only preferentially enriched at CpG islands. In contrast, Hela cells presented a reverse pattern with highest H3K27me3 enrichment in intergenic regions. To confirm this result in Hela cells, we performed two independent replicates of ChIP-Seq and ChIP-BS-seq. Cause of useful was relative small. we still sequenced one 100bp pe reads replicate for H3K4me3 and two replicate for H3K27me3 ChIP-BS-seq.
Project description:Genome wide DNA methylation profiling of androgen-sensitive and –refractory prostate cancer cells. The Illumina Infinium HumanMethylation450 Beadchip was used to obtain DNA methylation profiles across approximately 480.000 CpGs in Prostate cancer cell lines showing different sensitivity to hormonal treatments. Samples included the androgen receptor negative cell lines PC3 and DU145, the androgen sensitive cell line LNCaP and the LNCaP abl cell line expressing androgen receptor but refractory prostate cancer cell line to hormonal treatments.
Project description:Genome-wide DNA methylation profiling of human PC3 invasive prostate cancer cell line treated with vehicle control (SAH, S-adenosylhomocysteine) and with SAM (S-adenosylmethionine) as well as of untreated human LNCaP non-invasive prostate cancer cell line. The Illumina Infinium 450k Human DNA Methylation BeadChip v1.2 was used to obtain DNA methylation profiles across approximately 450,000 CpGs in human cell lines exposed to described treatments. Samples included biological triplicate of PC3 control (SAH treated), biological triplicate of PC3 treated with SAM, and biological duplicate of LNCaP untreated. Bisulfite-converted DNA from the 8 samples were hybridised to the Illumina Infinium 450k Human Methylation BeadChip v1.2.
Project description:The polycomb group (PcG) protein, EZH2, possesses oncogenic properties for which the underlying mechanism is unclear. In this set of experiments, we sought to identify a robust set of Suz12-occupied gene promoters in prostate cancer cell lines. Genome-wide location analysis (ChIP-chip) of SUZ12 was performed in both the PC3 and LNCaP prostate cancer cell lines using an IgG ChIP-chip as a control. There are total 3 hybridizations, including IgG ChIP-chip of PC3 cells, Suz12 ChIP-chip of PC3 and LNCaP cells.
Project description:PC3 are a metastatic prostate cancer cell line. Microarray analysis was performed to evaluate the impact of miR-149-3p overexpression or DAB2IP depletion in PC3.
Project description:To identify genomic regions which display concordant gene expression in prostate cancer, we performed expression profiling of normal prostate epithelial cells (PrEC) and the prostate cancer cell line LNCaP. These expression arrays were integrated ChIP-on-chip studies of active and repressive epigenetic marks in same cells to discover and characterise regions of Long Range Epigenetic Silencing (LRES) in prostate cancer.