Deletion of chromosome 13q and 14q is a common feature of tumors with BRCA2 mutations
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ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Michel Longy
PROVIDER: E-GEOD-39710 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:In colorectal cancer (CRC), chromosomal instability (CIN) is typically studied using comparative-genomic hybridization (CGH) arrays. We studied paired (tumor and surrounding healthy) fresh-frozen tissue from 86 CRC patients using Illumina’s Infinium-based SNP array. This method allowed us to study CIN in CRC, with simultaneous analysis of copy number (CN) and B-allele frequency (BAF), which is a representation of allelic composition. This data helped us to detect mono-allelic and bi-allelic amplifications/deletion, copy neutral loss of heterozygosity, and levels of mosaicism for mixed cell populations, some of which can not be assessed with other methods that do not measure BAF. We identified associations between CN abnormalities and different CRC phenotypes (MSI, histological diagnosis, location, tumor grade, stage, MSI and presence of lymph node metastasis). We showed commonalities between regions of CN change observed in CRC and the regions reported in previous studies of other solid cancers (e.g., amplifications of 20q, 13q, 8q, 5p and deletions of 18q, 17p and 8p). From the Therapeutic Target Database we found relevant drugs, targeted to the genes located in these regions with CN changes, approved or in trials for other cancers and common diseases. These drugs may be considered for future therapeutic trials in CRC, based on personalized cytogenetic diagnosis. We also found many regions harboring genes which are not currently targeted by any relevant drugs that may be considered for future drug discovery studies. Our study shows the application of high-density SNP arrays for cytogenetic study in CRC and its importance for personalized treatment. DNA was extracted from colon tissue samples provided by 86 CRC patients. Each patient provided paired CRC tumor tissue and adjacent normal colon mucosa samples, which were fresh-frozen after resection. Samples were genotyped using Illumina's Infinium-based 610 Quad and CytoSNP 12 microarray chips. The genotype data from paired tumor and normal samples was used to detect tumor-specific chromosomal instabilities in copy number, including copy-neutral LOH, which cannot be assessed by many other cytogenetic methods. Supplementary file "GSE34678_raw_GPL8887.txt" includes the raw data for Samples using GPL8887 (GSM853162-GSM853239); supplementary file "GSE34678_raw_GPL13829.txt" includes the raw data for Samples using GPL13829 (GSM853240-GSM853363).
2014-12-19 | E-GEOD-34678 | biostudies-arrayexpress
Project description:Chromosomal instability is central to the process of carcinogenesis. The detection of somatic chromosomal alterations in small premalignant lesions genome-wide remains challenging since sample heterogeneity dilutes the aberrant cell information. We introduced an analytic metric termed "delta-θ", and applied this metric to a titrated cancer cell model using a pair of cancer cell line and matched lymphoblastoid cell line. We examined heterogeneous clinical specimens including bronchial biopsies and brushings with this metric. Distinctive genomic variation were successfully detected across the whole genome in invasive cancer cases (6/6), carcinoma in situ (3/3), and high grade dysplasia (severe or moderate) (3/11). We modeled titration series (100%, 25%, 12.5%, 6.3%, 3.1%, 1.6% and 0% tumor content) mixing the genomic DNA of the cell line pair. We also investigated 30 malignant/premalignant samples from 18 patients with heavy smoking histories (6 invasive lung cancer, 3 carcinoma in situ,15 dysplasia, 3 hyperplasia and 3 normal histology) using Illumina HumanOmni2.5 and Human 660w SNP microarrays. All of them were paired with matched reference blood DNA and analyzed.
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Project description:Genome-wide association studies (GWAS) have been pivotal to increasing our understanding of intestinal disease. However, the mode by which genetic variation results in phenotypic change remains largely unknown, with many associated polymorphisms likely to modulate gene expression. Analyses of expression quantitative trait loci (eQTL) to date indicate that as many as 50% of these are tissue specific. Here we report a comprehensive eQTL scan of intestinal tissue. Subjects who had undergone ileal pouch anal anastomosis and closure of ileostomy at least one year prior to recruitment were prospectively enrolled at Mount Sinai Hospital in Toronto. Endoscopically and histologically normal tissue biopsies from the afferent limb of these individuals were obtained and preserved in RNAlater. Total RNA was extracted with the QIAGEN miRNeasy Kit and mRNA analysis was performed on Affymetrix Human Gene 1.0 ST arrays. DNA was obtained from whole-blood samples from the same individuals and genotyped using the Illumina beadchips. Cis- and trans-eQTL analyses were carried out on 173 subjects encompassing the expression levels of 19,047 unique autosomal genes listed in the NCBI database and over 580K dbSNPs (Call Rate ? 95%; MAF ? 5%; Hardy–Weinberg equilibrium (HWE) ?2 p-values ? 10-6). This work was done in a custom software pipeline and the Kruskal-Wallis test was used to compare expression values across different genotypes. False discovery rate correction for multiple testing was applied at an alpha level of 5%.
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2011-12-02 | E-GEOD-31645 | biostudies-arrayexpress
Project description:Chromosome segregation errors have been linked to DNA damage and genomic rearrangements. Accumulating evidence has shown that catastrophic genomic rearrangements, like chromothripsis, can result from lagging chromosomes undergoing aberrant DNA replication and DNA damage in micronuclei. Detailed characterization of genomic rearrangements resulting from DNA damage in micronuclei has been hampered because of difficulties in culturing daughter cells with DNA damage. Here, we employ a method by which a specific single chromosome is trapped in a micronucleus, followed by transfer to an acceptor cell. Next, stably propagating clonal cell lines with an extra chromosome were established and analyzed by copy number profiling and whole genome sequencing. While non-transformed, p53 proficient and telomerase-immortalized RPE1 cells showed a stable genome following addition of the transferred chromosome, we observed frequent de novo genomic rearrangements in cells derived from the HCT116 colorectal cancer cell line after chromosome transfer. The de novo rearrangements varied from simple deletions and duplications to complex rearrangements. Phase-informative SNPs revealed that the rearrangements specifically occurred on the transferred chromosome. We found that the complex rearrangements recapitulated all features of chromothripsis, including massive oscillation between two copy number states, localization to a single chromosome, random joining of chromosome fragments and non-homologous or micro-homologous repair. We describe an approach that enables the isolation of clonal cell lines with genomic rearrangements and chromothripsis on a specific chromosome in p53 proficient cells. The procedure enables further investigation of the exact mechanism leading to chromothripsis and the analysis of its consequences for cell survival (viability) and cancer development. We analyzed 38 cell clones, originating from HCT116 or RPE1 cells respectively, with Illumina beadchip arrays to test for unique de novo copy number variants and to determine the chromosome affacted by the CNAs.
2015-08-13 | E-GEOD-71978 | biostudies-arrayexpress
Project description:Hibernomas are benign tumors with morphological features resembling brown fat. They consistently display cytogenetic rearrangements, typically translocations, involving chromosome band 11q13. Here we demonstrate that these aberrations are associated with concomitant deletions of AIP and MEN1, tumor suppressor genes that are located 3 Mb apart and that underlie the hereditary syndromes pituitary adenoma predisposition and multiple endocrine neoplasia type I. MEN1 and AIP displayed a low expression in hibernomas whereas the expression of genes up-regulated in brown fat-PPARA, PPARG, PPARGC1A, and UCP1-was high. Thus, loss of MEN1 and AIP is likely to be pathogenetically essential for hibernoma development. Simultaneous loss of two tumor suppressor genes has not previously been shown to result from a neoplasia-associated translocation. Furthermore, in contrast to the prevailing assumption that benign tumors harbor relatively few genetic aberrations, the present analyses demonstrate that a considerable number of chromosome breaks are involved in the pathogenesis of hibernoma. Global copy number analysis was performed using single nucleotide polymorphism (SNP) array. Cases 1-14 were hybridized onto Illumina Human1M-Duo v3.0 (and Human CNV370-Quad v3.0) BeadChip (Illumina, San Diego, CA, USA), following standard protocols supplied by the manufacturer. Case 15 was analyzed using Illumina Human Omni-Quad BeadChip. Normal blood DNA was analyzed in cases 1, 2, 4 and 6 using the Human CNV370-Quad v3.0 BeadChip. Data analysis was done using the BeadStudio software (Illumina).
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