4219 results for "*oma"

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• Molecular features of adenomas predicting metachronous colorectal cancer: a nested-case control study

  "Background & Aims: Current morphological features defining advanced adenomas (size ≥10 mm, high grade dysplasia or >25% villous component) cannot optimally distinguish individuals at high-risk or low-risk of metachronous colorectal cancer (me-CRC), which may result in suboptimal surveillance. Certain DNA copy number alterations are associated with adenoma-to-carcinoma progression (cancer-associated events; CAEs). We aimed to evaluate whether CAEs can better predict an individual’s risk of me-CRC than the morphological advanced adenoma features. Methods: In this nested case-control study, 529 individuals with a single adenoma at their first colonoscopy were selected from a Norwegian adenoma cohort. DNA copy number profiles were determined, by means of low-coverage whole genome sequencing. We assessed the prevalence of CAEs in advanced and non-advanced adenomas and its association with me-CRC. For the latter, cases (with CRC) were matched to controls (without CRC), with the same follow-up period as cases, as well as age and sex. Subsequently, odds ratios (OR) for the association of the presence of an advanced adenoma or a molecularly-defined high-risk adenoma with me-CRC were calculated. Results: Molecular high-risk features were observed in 85/267 (32%) of advanced adenomas and in 27/262 (10%) of non-advanced adenomas. Me-CRC was more strongly associated with advanced adenomas (OR 3.58; 95% CI 2.27-5.72) than with molecular high-risk adenomas (OR 1.90; 95% CI 1.14–3.16). After adjusting for other variables, only advanced adenoma remained significantly associated with me-CRC (OR 3.39; 95% CI 2.10–5.55). Conclusion: Molecularly-defined high-risk adenomas were associated with me-CRC, but the association of advanced adenoma with me-CRC was stronger. " Project goal: Evaluate the value of DNA copy numbers alterations detected in a baseline adenoma, in the prediction of risk of metachronous CRC

  Study EGAS00001007039

• RNAseq of 76 samples from Uveal Melanoma tumors

  Hotspot mutations in the spliceosome gene SF3B1 are reported in 20% of uveal melanomas. SF3B1 is involved in 3'-splice site (3'ss) recognition during RNA splicing; however, the molecular mechanisms of its mutation have remained unclear. Here we show, using RNA-Seq analyses of uveal melanoma, that the SF3B1 R625/K666 mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 3'ss

  Study EGAS00001002932

• Methylation-based classification of human mesenchymal chondrosarcoma

  We applied methylome and copy number profiling to a set of 45 well characterized MCS cases to evaluate their potential diagnostic value. Notably, the findings were reproducible also when analysing the round cell and cartilaginous component separately. Furthermore, four outliers were identified by methylome profiling for which the diagnosis had to be revised. Methylome profiling represents a sensitive, specific and reliable tool to support the diagnosis of MCS, particularly if only the round cell component is obtained in a biopsy and the diagnosis is not suspected. It can furthermore aid in confirming the diagnosis in case RNA sequencing for the HEY1::NCOA2 fusion transcript is not available.

  Study EGAS00001007042

• Revealing active mutational processes in tumours using DigiPico/MutLX at unprecedented accuracy

  Active mutational processes in a tumor result in genetic micro-heterogeneity that can determine the tumor’s evolutionary trajectory. Identification of these processes by studying micro-heterogeneity can unveil novel aspects of tumor evolution with potential therapeutic implications. Such studies, however, are inherently problematic because of the discovery of excessive false positive mutations. Here we report the optimization and validation of a robust whole genome sequencing and analysis pipeline (DigiPico/MutLX) that virtually eliminates false positive results. Using our method, we identified, for the first time, a sub-clonal local hyper-mutation (kataegis) event in a recurrent ovarian carcinoma, which was unidentifiable from the bulk WGS data of the same tumor. Overall, we propose DigiPico/MutLX method as a powerful framework for the reliable study of genetic micro-heterogeneity in tumor and normal tissues.

  Study EGAS00001003555

• Linked-read based analysis of Medulloblastomas

  Medulloblastoma (MB) is the most common type of malignant pediatric brain tumor with group 4 medulloblastomas (G4 MBs) accounting for 40% of cases of medulloblastomas. The molecular mechanisms that underlie this subgroup are still poorly understood. Point mutations are detected in a large number of genes at low incidence per gene while the detection of complex structural variants (SVs) in recurrently affected gene typically requires the application of long-read technologies. Here, we applied linked-read sequencing, which combines the long-range genome information of long-read sequencing with the high base pair accuracy of short read sequencing and very low sample input requirements.

  Study EGAS00001007064

• Treatment stratification and biomarker validation using patient-derived head and neck cancer organoids

  Background Organoids are three-dimensional structures that can be grown from patient-derived material including carcinomas. These in vitro models can be cryopreserved to generate “living” biobanks that reflect patient heterogeneity. Head and neck cancer (HNC) is a collective term used for tumors arising in the head and neck area, including squamous cell carcinomas (HNSCC) and adenocarcinoma of the salivary gland. Methods to culture patient-derived HNC organoids have previously been described. Methods Organoids were derived from resection or biopsy material of patients included between 2016 and 2022. Organoids were characterised with immunohistochemistry and whole exome sequencing (WES) and exposed to chemo-, radio- and targeted-therapies. CRISPR/Cas9-based gene editing was applied to validate proposed biomarkers. Results We have extended our previously published organoid biobank to a total of 110 organoid models, some of which were characterised by histology and WES. Organoids recapitulated both single nucleotide variants and copy number alterations as found in patient HNSCC samples. Organoid and patient response to radiotherapy (RT; primary (n=6) and adjuvant (n=15)) could be compared in 21 HNC cases. In the adjuvant RT group, organoids derived from patients that relapsed were more resistant to RT in vitro, showing potential for guiding treatment options in this subset of patients. Conclusion Taken together, these results indicate illustrate the potential of organoids as a diagnostic tool in personalised medicine for HNC and indicate the potential of this technology for biomarker discovery and validation within the context of relevant patient heterogeneity.

  Study EGAS00001007076

• Recapitulation of genetic predisposition to medulloblastoma in human neuroepithelial stem cells

  Human neural stem cell cultures provide progenitor cells that are potential cells of origin for brain cancers. However, the extent to which genetic predisposition to tumor formation can be faithfully captured in stem cell lines is uncertain. Here we evaluated neuroepithelial stem (NES) cells, representative of cerebellar progenitors. We transduced NES cells with MYCN, observing medulloblastoma upon orthotopic implantation in mice. Significantly, transcriptomes and patterns of DNA methylation from xenograft tumors were globally more representative of human medulloblastoma compared to a MYCN-driven genetically engineered mouse model. Orthotopic transplantation of NES cells generated from Gorlin syndrome, patients predisposed to medulloblastoma due to germline mutated PTCH1, also generated medulloblastoma. We engineered candidate cooperating mutations in Gorlin NES cells, with mutation of DDX3X or loss of GSE1 both accelerating tumorigenesis. These findings demonstrate that human NES cells provide a potent experimental resource for dissecting genetic causation in medulloblastoma.

  Study EGAS00001003620

• Oral mucosa organoids as a potential model for personalized therapies

  Organoids were established from both tumor and matched wildtype tissue from patients diagnosed with head and neck squamous cell carcinoma (HNSCC). In order to confirm tumor status and identify oncogenic driver mutations, DNA derived of these organoids was sequenced. After validation of tumor identity, organoids were exposed to a range of (targeted) chemotherapeutics and radiotherapy. Differential responses to therapeutics were subsequently correlated to underlying genetic alterations to see if DNA mutation status could be predictive for responses to therapy.

  Study EGAS00001003628

• Infant Glioma Molecular Subtype

  Infant gliomas have completely different clinical behavior than gliomas in children and adults. Low-grade tumors are more aggressive with a higher mortality rate, while high-grade tumors are more benign. However, we have little understanding of their biology and so cannot explain this behavior and what constitutes optimal clinical management. To solve this enigma, we performed a comprehensive genetic analysis of the largest cohort to date of infantile gliomas. We uncovered several important findings which dramatically change the management of these cancers. Infant hemispheric gliomas harbor unique alterations in ROS, ALK, MET and other genes found in adult carcinomas. Unlike in adults, they are typically the only alteration present and some of these tumors regress from high- to low-grade partially explaining their favorable clinical outcome. Midline gliomas harbor RAS/MAPK pathway mutations, progress rapidly, and do not respond to current chemoradiation approaches, partially explaining their poorer outcome. These data suggest that infant gliomas require different therapeutic approaches including early use of targeted therapies.

  Study EGAS00001003714

• Gene expression profile of mesothelial-derived carcinoma-associated fibroblasts

  RNA-sequencing was carried out on ascetic fluid-isolated mesothelial cells from low-grade serous ovarian cancer patients, high-grade serous ovarian cancer patients, chemotherapy-treated high-grade serous ovarian cancer patients and control mesothelial cells obtained from non-oncologic patients to identify differentially expressed genes associated to mesothelial-to-mesenchymal transition process.

  Study EGAS00001003747