3331 results for "ovarian cancer"

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• Genomic Heterogeneity and the Small Renal Mass

  Tumor heterogeneity is believed to represent a barrier to pre-operative genomic characterization in kidney cancer. Previous studies of heterogeneity in clear cell renal cell carcinoma (ccRCC) evaluated only large and metastatic tumors. In small renal tumors in which multiple biopsies are not feasible, the extent of heterogeneity remains unknown. In this study, we evaluated how the extent of genomic heterogeneity in small and large ccRCC. A total of 23 small (<4cm ) and 24 large (>7cm ) ccRCC had 3 regions sampled for evaluation of copy number, clear-cell A/clear-cell B (ccA/ccB) classification, and cell cycle progression (CCP) score. Small tumors have less genomic complexity and significantly fewer subclonal events. Pre-treatment genomic characterization based on a single biopsy in small ccRCC can provide insight into biologic potential to make clinical decisions.

  Study EGAS00001002919

• multi-OMICs study of a pair of infant monozygotic twins with concordant B-cell ALL

  B-cell acute lymphoblastic leukemia (B-cell ALL) is the most common cancer in childhood. Studying identical twins with B-cell ALL provides a unique and tractable model for deciphering the developmental timing of pre- and post-natal mutations contributing to clonal evolution. To date, this has mainly focused on major cytogenetic subgroups of childhood B-cell ALL, including MLL fusions, ETV6-RUNX1, hyperdiploidy, and BCR-ABL1. However, formal demonstration of the prenatal origin and “backtracking” the natural history of the leukemia remains understudied in “B-other”/Normal Karyotype (NK) B-cell ALL. To characterize the genetic and the epigenetic landscape of this particular leukemia subtype, we performed whole genome DNA-, B-cell receptor (BCR)-, and DNA bisulfite-sequencing on a pair of 8-month-old monozygotic twins diagnosed with concordant “B-other”/NK B-cell ALL.

  Study EGAS00001003651

• Accurate mapping of mitochondrial DNA deletions and duplications using deep sequencing

  Deletions and duplications in mitochondrial DNA (mtDNA) cause mitochondrial disease and accumulate in conditions such as cancer and age-related disorders, but validated high-throughput methodology that can readily detect and discriminate between these two types of events is lacking. Here we present MitoSAlt, a computational method for accurate identification, quantification and visualization of mtDNA deletions and duplications from whole genome, whole exome or transcriptome sequencing data. MitoSAlt was tested on simulated sequencing reads and human patient samples with single deletions and duplications to verify its accuracy. Application to mouse models of mtDNA maintenance disease further demonstrated the ability to detect deletions and duplications even at low levels of heteroplasmy. MitoSAlt paves the way for simple and reliable determination of mtDNA deletions and duplications across a wide range of relevant conditions and available sequencing datasets.  

  Study EGAS00001004380

• Colorectal advanced adenomas NKI-AvL TGO COCOS series

  Colorectal cancer (CRC) develops from normal epithelium, through a benign precursor lesion called adenoma, by accumulation of genetic alterations affecting oncogenes and tumour suppressor genes. About 5% of colorectal adenomas are estimated to progress to CRC. However, it is important to identify which adenomas actually carry a high-risk of progression, because these serve as intermediate endpoints for e.g. screening programs. In clinical practice, adenomas with a size of ≥10 mm, villous component and/or high-grade dysplasia, called advanced adenomas, are considered high-risk, although solid evidence for this classification is lacking. Specific DNA copy number changes are associated with adenoma-to-carcinoma progression.For this tissue dataset, we applied low-pass whole genome sequencing to 96 advanced adenomas. Advanced adenomas were classified as lesions with low-risk or high-risk of progression, according to the presence of specific DNA copy number changes (Carvalho et al, CancerPrevRes, 2018).

  Study EGAS00001002952

• Novel mutations in TOP2A in gliomas

  High grade gliomas (HGGs) are aggressive, primary brain tumors with poor clinical outcomes. To better understand glioma pathobiology and find potential therapeutic susceptibilities, we designed a custom- panel 664 cancer- and epigenetics-related genes and employed targeted next generation sequencing to study the genomic landscape of somatic and germline variants in 182 glioma samples of different malignancy grades. Besides known alterations in TP53, IDH1, ATRX, EGFR genes, we found several novel variants that can be potential drivers in gliomas. In four patients from the Polish glioma cohort, we identified a novel recurrent mutation in the TOP2A gene coding for Topoisomerase 2A in glioblastomas (GBM, WHO grade IV gliomas). The mutation results in a substitution of glutamic acid (E) 948 to glutamine (Q) of TOP2 A and we predicted this E948Q substitution may affect DNA binding and a TOP2A enzymatic activity.

  Study EGAS00001004556

• Oncogenic chimeric transcription factors drive tumor-specific transcription, processing, and translation of silent genomic regions

  Many cancers are characterized by gene fusions encoding oncogenic chimeric transcription factors (TFs) such as EWS::FLI1 in Ewing sarcoma (EwS). Here, we find that EWS::FLI1 induces the robust expression of a specific set of novel spliced and polyadenylated transcripts within otherwise transcriptionally silent regions of the genome. These neogenes (NGs) are virtually undetectable in large collections of normal tissues or non-EwS tumors and can be silenced by CRISPR interference at regulatory EWS::FLI1-bound microsatellites. Ribosome profiling and proteomics further show that some NGs are translated into highly EwS-specific peptides. More generally, we show that hundreds of NGs can be detected in diverse cancers characterized by chimeric TFs. Altogether, this study identifies the transcription, processing, and translation of novel, specific, highly expressed multi-exonic transcripts from otherwise silent regions of the genome as a new activity of aberrant TFs in cancer.

  Study EGAS00001006293

• single-stranded DNA study

  A ssDNA library protocol was applied to cfDNA from plasma samples obtained from different DNA extraction methods and revealed significant differences in DNA fragmentation patterns in comparison to dsDNA-based protocols. In particular, a specific combination of methods revealed a population of ultrashort fragments, organized at ~50 bp. We observed significant differences in the relative abundance of these ultrashort DNA fragments in plasma from healthy individuals and cancer patients. Through shallow whole genome sequencing (sWGS, <0.5-fold coverage) and the analysis of somatic copy number aberrations (SCNA), we determined the landscape of genetic alterations in this newly identified population of cfDNA fragments. In addition, we studied their potential link with regulatory regions by investigating the genome-wide coverage patterns at transcription start sites (TSS). Furthermore, we demonstrated that the ultrashort cfDNA fragments map to regions associated with secondary DNA structures, G-quadruplexes (G4s).

  Study EGAS00001005093

• Effects of busulfan, fludarabine and clofarabine treatment on human small intestinal organoids generated from healthy donors

  The intestine is vulnerable to chemotherapy-induced toxicity due to its high epithelial proliferative rate, making gut toxicity an off-target effect in several cancer treatments, including conditioning regimens for allogeneic hematopoietic cell transplantation (HSCT). In HSCT, intestinal damage is an important factor in the development of Graft-versus-Host Disease (GVHD), an immune complication in which donor immune cells attack the recipient's tissues. Here, we developed a novel human intestinal organoid-based 3D model system to study the effects of chemotherapy-induced intestinal epithelial damage at the RNA level. We show that chemotherapy conditioning specifically reprograms the intestinal epithelial transcriptome after treatment with either busulfan (3.5μM), fludarabine (15μM) or clofarabine (0.5μM) for 24h. This knowledge can potentially enable us to understand which changes undergo in healthy tissues upon conditioning and how those are related with immune activation typical in GVHD.

  Study EGAS00001007550

• Palindromic Amplification of The ERBB2 Oncogene in HER2-Positive Breast Cancer

  DNA Inverted Repeats as an At-risk Motif for Palindromic Gene Amplificatio defines oncogene amplification that is configured as a series of inverted duplications (palindromic gene amplification). There are several, recurrently amplified oncogenes throughout the human genome. However, it remains unclear whether this recurrent amplification is solely a manifestation of increased fitness resulting from random amplification mechanisms, or if genomic locus-specific amplification mechanism plays a role. In this study, we show that the ERBB2 oncogene at 17q12 is susceptible to palindromic gene amplification in HER2-positive breast tumors. We investigated eight tumors in this study, of which five tumors were HER2-positive, and three tumors were HER2-negative. HER2-status was determined by clinical FISH tests. We applied three genomic approaches to investigate the amplification mechanism: (1) copy number analysis by array-CGH on the Affymetrix SNP6.0 platform (8 files), (2) sequencing of DNA libraries enriched with tumor-derived palindromic DNA (Genome-wide Analysis of Palindrome Formation, GAPF-seq) (8 files) and (3) unbiased whole genome sequencing (WGS) (1 file). These molecular data is made available in the dbGaP. Genomic studies using tumor DNA was approved under the Internal Institutional Review Board at the Cleveland Clinic (IRB07-136: EXEMPT: Chromosome Breakage and DNA Palindrome Formation). Specimens were obtained and methods were carried out under the auspices of IRB 7881 (Evaluation of Genetic and Molecular Markers in Patients with Breast Cancer). All patients consented to allow their cancer specimens to be used by researchers in an anonymized fashion. The consent form indicates that publication will take place without identifiers to protect the identity of any specific individual. We observed significant and enrichment of palindromic DNA within amplified ERBB2 genomic segments in four out of five HER2-positive tumors. None of three HER2-negative tumors showed such enrichment. Palindromic DNA was particularly enriched at amplification peaks and boundaries between amplified and normal copy-number regions. Thus, palindromic gene amplification shaped the amplified ERBB2 locus. The moderate enrichment of palindromic DNA throughout the amplified segments leads us to propose that the ERBB2 locus is amplified through a mechanism that repeatedly generates palindromic DNA, such as Breakage-Fusion-Bridge cycles. Our results reveal a potential interaction between local genomic environments and gene amplification mechanisms. This study is published under the title "Palindromic amplification of the ERBB2 oncogene in primary HER2-positive breast tumors" (PMID:28211519).

  Study phs001261

• Immunoreactive_p53_areas_in_human_skin_2

  Previous work has suggested that in mice there may be a difference in mutational burden between areas expressing stabilised p53 protein and others. We wish to see if this observation holds true in human sun-exposed epidermis. We will take 0.25mm punch biopsies from peeled human skin epidermis which will be submitted to the low input pipeline prior to sequencing.

  Study EGAS00001004463