Unknown,Transcriptomics,Genomics,Proteomics

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Isocitrate dehydrogenase 1 (IDH1) mutant gliomas demonstrate a distinct global CpG island methylation profile compared to IDH1 wildtype gliomas using MRSE

ABSTRACT: In order to identify other molecular aberrations that may cooperate with IDH1R132MUT in gliomagenesis, we performed CpG-island methylation profiling analysis using MSRE (Tran et al. Front. Neurosci. 3:57. Doi: 10.3389/neuro.15.005.2009) on a subset of IDH1R132MUT and IDH1R132WT GBMs and found a distinct pattern of CpG island hypermethylation that was detected in all GBMs and lower grade gliomas with IDH1R132MUT. While absent from nearly all IDH1R132WT glioma, the methylation pattern in IDH1R132MUT GBMs shows similarity to the recently reported CpG island methylator phenotype (CIMP) found to be tightly associated with IDH1R132MUT gliomas(Noushmehr et al. Cancer Cell, Volume 17, Issue 5, 18 May 2010, Pages 510-522, ISSN 1535-6108, DOI: 10.1016/j.ccr.2010.03.017). Methylation profiling performed on 40 distinct brain tumor samples: 7 Anaplastic Astrocytomas, including 3 IDH1MUT and 4 IDH1WT; 5 Lowgrade Astrocytomas, including 4 IDH1MUT and 1 IDH1WT; 28 Glioblastoma, including 8 IDH1MUT and 20 IDH1WT.

ORGANISM(S): Homo sapiens

SUBMITTER: Reshmi Chowdhury

PROVIDER: E-GEOD-28271 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Genome wide methylation profiling of gliomas is likely to provide important clues to improving treatment outcomes. Restriction enzyme based approaches have been widely utilized for methylation profiling of cancer genomes and will continue to have importance in combination with higher density microarrays. With the availability of the human genome sequence and microarray probe sequences, these approaches can be readily characterized and optimized via in silico modeling. We adapted the previously described HpaII/MspI based Methylation Sensitive Restriction Enzyme (MSRE) assay for use with two-color Agilent 244K CpG island microarrays. In this assay, fragmented genomic DNA is digested in separate reactions with isoschizomeric HpaII (methylation-sensitive) and MspI (methylation-insensitive) restriction enzymes. Using in silico hybridization, we found that genomic fragmentation with BfaI was superior to MseI, providing a maximum effective coverage of 22,362 CpG islands in the human genome. In addition, we confirmed the presence of an internal control group of fragments lacking HpaII/MspI sites which enable separation of methylated and unmethylated fragments. We used this method on genomic DNA isolated from normal brain, U87MG cells, and a glioblastoma patient tumor sample and confirmed selected differentially methylated CpG islands using bisulfite sequencing. Along with additional validation points, we performed a receiver operating characteristics (ROC) analysis to determine the optimal threshold (p â¤ 0.001). Based on this threshold, we identified ~2400 CpG islands common to all three samples and 145 CpG islands unique to glioblastoma. These data provide general guidance to individuals seeking to maximize effective coverage using restriction enzyme based methylation profiling approaches. Five samples: normal human brain DNA, U87MG cell line, glioblastoma tumor, human DNA treated with SssI enzyme used as positive control, and Genomiphied human DNA used as negative control. Two technical replicates were performed on all samples except the negative control.

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Isocitrate dehydrogenase 1 (IDH1) mutant gliomas demonstrate a distinct global CpG island methylation profile compared to IDH1 wildtype gliomas using MRSE

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