| 1. |
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| 2. |
- Schepke, Elizabeth, et al.
(författare)
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DNA methylation profiling improves routine diagnosis of paediatric central nervous system tumours: A prospective population-based study
- 2022
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Ingår i: Neuropathology and Applied Neurobiology. - : Wiley. - 0305-1846 .- 1365-2990. ; 48:6
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Paediatric brain tumours are rare, and establishing a precise diagnosis can be challenging. Analysis of DNA methylation profiles has been shown to be a reliable method to classify central nervous system (CNS) tumours with high accuracy. We aimed to prospectively analyse CNS tumours diagnosed in Sweden, to assess the clinical impact of adding DNA methylation-based classification to standard paediatric brain tumour diagnostics in an unselected cohort. Methods: All CNS tumours diagnosed in children (0-18 years) during 2017-2020 were eligible for inclusion provided sufficient tumour material was available. Tumours were analysed using genome-wide DNA methylation profiling and classified by the MNP brain tumour classifier. The initial histopathological diagnosis was compared with the DNA methylation-based classification. For incongruent results, a blinded re-evaluation was performed by an experienced neuropathologist. Results: Two hundred forty tumours with a histopathology-based diagnosis were profiled. A high-confidence methylation score of 0.84 or more was reached in 78% of the cases. In 69%, the histopathological diagnosis was confirmed, and for some of these also refined, 6% were incongruent, and the re-evaluation favoured the methylation-based classification. In the remaining 3% of cases, the methylation class was non-contributory. The change in diagnosis would have had a direct impact on the clinical management in 5% of all patients. Conclusions: Integrating DNA methylation-based tumour classification into routine clinical analysis improves diagnostics and provides molecular information that is important for treatment decisions. The results from methylation profiling should be interpreted in the context of clinical and histopathological information.
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| 3. |
- Tüzesi, Ágota, 1982, et al.
(författare)
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Pediatric brain tumor cells release exosomes with a miRNA repertoire that differs from exosomes secreted by normal cells
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8:52, s. 90164-90175
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Tidskriftsartikel (refereegranskat)abstract
- High-grade gliomas (HGGs) are very aggressive brain tumors with a cancer stem cell component. Cells, including cancer stem cells, release vesicles called exosomes which contain small non-coding RNAs such as microRNAs (miRNAs). These are thought to play an important role in cell-cell communication. However, we have limited knowledge of the types of exosomal miRNAs released by pediatric HGG stem cells; a prerequisite for exploring their potential roles in HGG biology. Here we isolated exosomes released by pediatric glioma stem cells (GSCs) and compared their repertoire of miRNAs to genetically normal neural stem cells (NSCs) exosomes, as well as their respective cellular miRNA content. Whereas cellular miRNAs are similar, we find that the exosomal miRNA profiles differ between normal and tumor cells, and identify several differentially expressed miRNAs. Of particular interest is miR-1290 and miR-1246, which have previously been linked to 'stemness' and invasion in other cancers. We demonstrate that GSC-secreted exosomes influence the gene expression of receiving NSCs, particularly targeting genes with a role in cell fate and tumorigenesis. Thus, our study shows that GSCs and NSCs have similar cellular miRNA profiles, yet differ significantly in the repertoire of exosomal miRNAs and these could influence malignant features of HGG. © Tuzesi et al.
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| 4. |
- Wenger, Anna, 1990, et al.
(författare)
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Determinants for Effective ALECSAT Immunotherapy Treatment on Autologous Patient-Derived Glioblastoma Stem Cells.
- 2018
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Ingår i: Neoplasia. - : Elsevier BV. - 1476-5586 .- 1522-8002. ; 20:1, s. 25-31
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma (GBM) is the most aggressive primary brain tumor with a median survival of less than 15 months, emphasizing the need for better treatments. Immunotherapy as a treatment for improving or aiding the patient's own immune defense to target the tumor has been suggested for GBM. A randomized clinical trial of adoptive cell transfer using ALECSAT (Autologous Lymphoid Effector Cells Specific Against Tumor Cells) is currently ongoing in Sweden. Here we performed a paired pre-clinical study to investigate the composition and in vitro effect of ALECSAT and identify determinants for the effect using autologous GBM-derived cancer stem cells (CSC), immunocytochemistry and flow cytometry. We show a clear dose-response relationship of ALECSAT on CSC, suggesting that the number of infused cells is of importance. In addition, the in vitro effect of ALECSAT on CSC correlated significantly to the blood count of T helper (Th) cells in the patient indicating a potential benefit of collecting cells for ALECSAT preparation at an even earlier stage when patients generally have a better blood count. The factors identified in this study will be important to consider in the design of future immunotherapy trials to achieve prolonged survival.
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| 5. |
- Wenger, Anna, 1990, et al.
(författare)
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Stem cell cultures derived from pediatric brain tumors accurately model the originating tumors.
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8, s. 18626-18639
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Tidskriftsartikel (refereegranskat)abstract
- Brain tumors are the leading cause of cancer-related death in children but high-grade gliomas in children and adolescents have remained a relatively under-investigated disease despite this. A better understanding of the cellular and molecular pathogenesis of the diseases is required in order to improve the outcome for these children. In vitro-cultured primary tumor cells from patients are indispensable tools for this purpose by enabling functional analyses and development of new therapies. However, relevant well-characterized in vitro cultures from pediatric gliomas cultured under serum-free conditions have been lacking. We have therefore established patient-derived in vitro cultures and performed thorough characterization of the cells using large-scale analyses of DNA methylation, copy-number alterations and investigated their stability during prolonged time in culture. We show that the cells were stable during prolonged culture in serum-free stem cell media without apparent alterations in morphology or growth rate. The cells were proliferative, positive for stem cell markers, able to respond to differentiation cues and initiated tumors in zebrafish and mice suggesting that the cells are cancer stem cells or progenitor cells. The cells accurately mirrored the tumor they were derived from in terms of methylation pattern, copy number alterations and DNA mutations. These unique primary in vitro cultures can thus be used as a relevant and robust model system for functional studies on pediatric brain tumors.
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| 6. |
- Ferreyra Vega, Sandra, et al.
(författare)
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Spatial heterogeneity in DNA methylation and chromosomal alterations in diffuse gliomas and meningiomas
- 2022
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Ingår i: Modern Pathology. - : Elsevier BV. - 0893-3952. ; 35:11, s. 1551-1561
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Tidskriftsartikel (refereegranskat)abstract
- Adult-type diffuse gliomas and meningiomas are the most common primary intracranial tumors of the central nervous system. DNA methylation profiling is a novel diagnostic technique increasingly used also in the clinic. Although molecular heterogeneity is well described in these tumors, DNA methylation heterogeneity is less studied. We therefore investigated the intratumor genetic and epigenetic heterogeneity in diffuse gliomas and meningiomas, with focus on potential clinical implications. We further investigated tumor purity as a source for heterogeneity in the tumors. We analyzed genome-wide DNA methylation profiles generated from 126 spatially separated tumor biopsies from 39 diffuse gliomas and meningiomas. Moreover, we evaluated five methods for measurement of tumor purity and investigated intratumor heterogeneity by assessing DNA methylation-based classification, chromosomal copy number alterations and molecular markers. Our results demonstrated homogeneous methylation-based classification of IDH-mutant gliomas and further corroborates subtype heterogeneity in glioblastoma IDH-wildtype and high-grade meningioma patients after excluding samples with low tumor purity. We detected a large number of differentially methylated CpG sites within diffuse gliomas and meningiomas, particularly in tumors of higher grades. The presence of CDKN2A/B homozygous deletion differed in one out of two patients with IDH-mutant astrocytomas, CNS WHO grade 4. We conclude that diffuse gliomas and high-grade meningiomas are characterized by intratumor heterogeneity, which should be considered in clinical diagnostics and in the assessment of methylation-based and molecular markers.
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| 7. |
- Kling, Teresia, 1985, et al.
(författare)
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DNA methylation-based age estimation in pediatric healthy tissues and brain tumors.
- 2020
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Ingår i: Aging. - : Impact Journals, LLC. - 1945-4589. ; 12:21, s. 21037-21056
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Tidskriftsartikel (refereegranskat)abstract
- Several DNA methylation clocks have been developed to reflect chronological age of human tissues, but most clocks have been trained on adult samples. The rapid methylome changes in children and the role of epigenetics in pediatric tumors calls for tools accurately estimating methylation age in children. We aimed to evaluate seven methylation clocks in multiple tissues from healthy children to inform future studies on the optimal clock for pediatric cohorts, and analyzed the methylation age in brain tumors. We found that clocks trained on pediatric samples were the best in all tested tissues, highlighting the need for dedicated clocks. For blood samples, the Skin and blood clock had the best correlation with chronological age, while PedBE was the most accurate for saliva and buccal samples, and Horvath for brain tissue. Horvath methylation age was accelerated in pediatric brain tumors and the acceleration was subtype-specific for atypical teratoid rhabdoid tumor (ATRT), ependymoma, medulloblastoma and glioma. The subtypes with the highest acceleration corresponded to the worst prognostic categories in ATRT, ependymoma and glioma, whereas the relationship was reversed in medulloblastoma. This suggests that methylation age has potential as a prognostic biomarker in pediatric brain tumors and should be further explored.
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| 8. |
- Kling, Teresia, 1985, et al.
(författare)
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Validation of the MethylationEPIC BeadChip for fresh-frozen and formalin-fixed paraffin-embedded tumours.
- 2017
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Ingår i: Clinical epigenetics. - : Springer Science and Business Media LLC. - 1868-7083 .- 1868-7075. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- DNA methylation is the most studied epigenetic modification due to its role in regulating gene expression, and its involvement in the pathogenesis of cancer and several diseases upon aberrations in methylation. The method of choice to evaluate genome-wide methylation has been the Illumina HumanMethylation450 BeadChip (450K), but it was recently replaced with the MethylationEPIC BeadChip (EPIC). We therefore sought to validate the EPIC array in comparison to the 450K array for both fresh-frozen (FF) and formalin-fixed paraffin-embedded (FFPE) tumours. We also performed analysis on the EPIC array with paired FF and FFPE samples to adapt to a clinical setting where FFPE is routinely used. Further, we compared two restoration methods, REPLI-g and Infinium, for FFPE-derived DNA on the EPIC array. The Pearson correlation of β values for common probes on the 450K and EPIC array was high for both FF (mean: 0.992) and FFPE (mean: 0.984) samples. The β values generated from the EPIC array for FFPE samples correlated well with the paired FF tumours, but varied between 0.901 and 0.987. We did note that sample pairs with lower correlation had less bimodal density distributions of β values and displayed higher noise in the copy number alteration plots (generated from the methylation array data) in the FFPE sample. Both REPLI-g and the Infinium restoration for FFPE samples performed well on the EPIC array and generated equivalent correlation scores to the paired FF sample.
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| 9. |
- Larsson, Susanna, et al.
(författare)
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Cell line-based xenograft mouse model of paediatric glioma stem cells mirrors the clinical course of the patient
- 2018
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 39:10, s. 1304-1309
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Tidskriftsartikel (refereegranskat)abstract
- The leading cause of cancer-related mortality among children is brain tumour, and glioblastoma multiforme (GBM) has the worst prognosis. New treatments are urgently needed, but with few cases and clinical trials in children, pre-clinical models such as patient-derived tumour xenografts (PDTX) are important. To generate these, tumour tissue is transplanted into mice, but this yields highly variable results and requires serial passaging in mice, which is time-consuming and expensive. We therefore aimed to establish a cell line-based orthotopic mouse model representative of the patient tumour. Glioma stem cell (GSC) lines derived from paediatric GBM were orthotopically transplanted into immunodeficient mice. Overall survival data were collected and histological analysis of the resulting neoplasias was performed. Genome-wide DNA methylation arrays were used for methylation and copy-number alterations (CNA) profiling. All GSC lines initiated tumours on transplantation and the survival of the mice correlated well with the survival of the patients. Xenograft tumours presented histological hallmarks of GBM, and were also classified as GBM by methylation profiling. Each xenograft tumour clustered together with its respective injected GSC line and patient tumour based on the methylation data. We have established a robust and reproducible cell line-based xenograft paediatric GBM model. The xenograft tumours accurately reflected the patient tumours and mirrored the clinical course of the patient. This model can therefore be used to assess patient response in pre-clinical studies.
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| 10. |
- Li, Jiuyi, et al.
(författare)
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Individual Assignment of Adult Diffuse Gliomas into the EM/PM Molecular Subtypes Using a TaqMan Low-Density Array.
- 2019
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Ingår i: Clinical cancer research : an official journal of the American Association for Cancer Research. - 1078-0432. ; 25:23, s. 7068-7077
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to develop a diagnostic platform to capture the transcriptomic resemblance of individual adult diffuse gliomas of WHO grades II-IV to neural development and the genomic signature associated with glioma progression.Based on the EM/PM classification scheme, we designed a RT-PCR-based TaqMan Low-density array (TLDA) containing 44 classifier and 4 reference genes. Samples of a training data set (GSE48865), characterized by RNA-sequencing, were utilized to optimize the TLDA design and to develop a support vector machine (SVM)-based prediction model. Complemented with Sanger sequencing for IDH1/2, and low coverage whole genome sequencing (WGS), the TLDA and SVM prediction model were tested in a validation (31 gliomas) and a test (121 gliomas) dataset.Independent of morphologically defined subtypes and grades, gliomas can be individually assigned into the EM and PM glioma subtypes with the respective areas under ROC curves at 0.86 and 0.85 in the validation dataset. The EM gliomas showed a medium overall survival (OS) of 15.6 months, whereas the medium OS for PM gliomas was not reached (hazard ratio = 3.55, 95% confidence interval: 1.96 to 6.45). The EM and PM gliomas showed distinct patterns of genomic alterations, with IDH mutation and 1p19q co-deletion in the PM gliomas and gain of chromosome 7/loss of chromosome 10 in the EM gliomas. Extensive chromosomal abnormalities marked the progression of PM gliomas.The integration of EM/PM subtyping, IDH sequencing and low coverage WGS may improve the risk stratification and selection of treatment regimens for glioma patients.
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| 11. |
- Wenger, Anna, 1990, et al.
(författare)
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CRISPR-Cas9 knockout screen identifies novel treatment targets in childhood high-grade glioma
- 2023
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Ingår i: Clinical Epigenetics. - 1868-7075. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundBrain tumours are the leading cause of cancer-related death in children, and there is no effective treatment. A growing body of evidence points to deregulated epigenetics as a tumour driver, particularly in paediatric cancers as they have relatively few genomic alterations, and key driver mutations have been identified in histone 3 (H3). Cancer stem cells (CSC) are implicated in tumour development, relapse and therapy resistance and thus particularly important to target. We therefore aimed to identify novel epigenetic treatment targets in CSC derived from H3-mutated high-grade glioma (HGG) through a CRISPR-Cas9 knockout screen.ResultsThe knockout screen identified more than 100 novel genes essential for the growth of CSC derived from paediatric HGG with H3K27M mutation. We successfully validated 12 of the 13 selected hits by individual knockout in the same two CSC lines, and for the top six hits we included two additional CSC lines derived from H3 wild-type paediatric HGG. Knockout of these genes led to a significant decrease in CSC growth, and altered stem cell and differentiation markers.ConclusionsThe screen robustly identified essential genes known in the literature, but also many novel genes essential for CSC growth in paediatric HGG. Six of the novel genes (UBE2N, CHD4, LSM11, KANSL1, KANSL3 and EED) were validated individually thus demonstrating their importance for CSC growth in H3-mutated and wild-type HGG. These genes should be further studied and evaluated as novel treatment targets in paediatric HGG.
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| 12. |
- Wenger, Anna, 1990
(författare)
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Deregulated epigenetics and cancer stem cells in brain tumours
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Glioblastoma (GBM) is an incurable brain tumour with dismal prognosis as the median survival for afflicted patients is only 8 months. Aberrations of epigenetic processes, which govern gene expression, are involved in cancer, but these epigenetic mechanisms are reversible and can potentially be corrected by treatment. One epigenetic mark, DNA methylation, can also be used for tumour classification. The aim of this thesis was to 1) establish a representative model system of paediatric GBM and use it to identify new epigenetic treatment targets, and 2) profile the epigenetic heterogeneity in adult and paediatric brain tumours and its effect on methylation-based classification. Patient-derived cancer stem cell (CSC) lines were established in paper I from paediatric GBM, and the cells retained the methylation pattern of the originating tumours. The CSC were injected into mice orthotopically in paper II and formed GBM tumours similar to the patient tumours. The survival of the injected mice correlated significantly with the survival of the patients, and the model thus reflects the clinical course of the patients. In paper III, we performed a CRISPR knockout screen with an epigenetic library and identified several novel genes as essential for the growth of CSC. Paper IV demonstrated that multiple methylation subclasses coexist within adult GBM, and that the methylation status of the clinically used biomarker MGMT varied. In contrast, the subclasses were stable across space and time in paediatric brain tumours in paper V. In conclusion, we showed that intratumour methylation heterogeneity is a feature of adult GBM and should be considered for methylation-based biomarkers and classification. The methylation classification was however homogeneous within paediatric brain tumours, which is promising as it is in clinical use for this patient group. We also established a representative in vitro and in vivo model system of CSC derived from paediatric GBM. With this model system, we identified candidate genes as tumour drivers and potential therapeutic targets in paediatric GBM.
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| 13. |
- Wenger, Anna, 1990, et al.
(författare)
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DNA methylation alterations across time and space in paediatric brain tumours
- 2022
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Ingår i: Acta Neuropathologica Communications. - : Springer Science and Business Media LLC. - 2051-5960. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- DNA methylation is increasingly used for tumour classification and has expanded upon the > 100 currently known brain tumour entities. A correct diagnosis is the basis for suitable treatment for patients with brain tumours, which is the leading cause of cancer-related death in children. DNA methylation profiling is required for diagnosis of certain tumours, and used clinically for paediatric brain tumours in several countries. We therefore evaluated if the methylation-based classification is robust in different locations of the same tumour, and determined how the methylation pattern changed over time to relapse. We sampled 3-7 spatially separated biopsies per patient, and collected samples from paired primary and relapse brain tumours from children. Altogether, 121 samples from 46 paediatric patients with brain tumours were profiled with EPIC methylation arrays. The methylation-based classification was mainly homogeneous for all included tumour types that were successfully classified, which is promising for clinical diagnostics. There were indications of multiple subclasses within tumours and switches in the relapse setting, but not confirmed as the classification scores were below the threshold. Site-specific methylation alterations did occur within the tumours and varied significantly between tumour types for the temporal samples, and as a trend in spatial samples. More alterations were present in high-grade tumours compared to low-grade, and significantly more alterations with longer relapse times. The alterations in the spatial and temporal samples were significantly depleted in CpG islands, exons and transcription start sites, while enriched in OpenSea and regions not affiliated with a gene, suggesting a random location of the alterations in less conserved regions. In conclusion, more DNA methylation changes accumulated over time and more alterations occurred in high-grade tumours. The alterations mainly occurred in regions without gene affiliation, and did not affect the methylation-based classification, which largely remained homogeneous in paediatric brain tumours.
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| 14. |
- Wenger, Anna, 1990, et al.
(författare)
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Intra-Tumor DNA Methylation Heterogeneity in Glioblastoma; Implications for DNA Methylation-Based Classification.
- 2019
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Ingår i: Neuro-oncology. - : Oxford University Press (OUP). - 1523-5866 .- 1522-8517. ; 21:5, s. 616-27
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Tidskriftsartikel (refereegranskat)abstract
- A feature of glioblastoma (GBM) is cellular and molecular heterogeneity, both within and between tumors. This variability causes a risk for sampling bias and potential tumor escape from future targeted therapy. Heterogeneous intra-tumor gene expression in GBM is well documented, but little is known regarding the epigenetic heterogeneity. Variability in DNA methylation within tumors would have implications for diagnostics, as methylation can be used for tumor classification, subtyping and determination of the clinically used biomarker MGMT promoter methylation. We therefore aimed to profile the intra-tumor DNA methylation heterogeneity in GBM and its effect on diagnostic properties.Three to four spatially separated biopsies per tumor were collected from 12 GBM patients. We performed genome-wide DNA methylation analysis and investigated intra-tumor variation.All samples were classified as GBM IDH wild type (wt)/mutated by methylation profiling, but the subclass differed within five tumors. Some GBM samples exhibited higher DNA methylation differences within tumors than between, and many CpG sites (mean: 17,000) had different methylation levels within the tumors. MGMT methylation status differed in IDH mutated patients (1/1).We demonstrated that intra-tumor DNA methylation heterogeneity is a feature of GBM. Although all biopsies were classified as GBM IDH wt/mutated by methylation analysis, the assigned subclass differed in samples from the same patient. The observed heterogeneity within tumors is important to consider for methylation-based biomarkers and future improvements in stratification of GBM patients.
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| 15. |
- Wenger, Anna, 1990, et al.
(författare)
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Methylation Profiling in Diffuse Gliomas: Diagnostic Value and Considerations
- 2022
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Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 14:22
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary Diffuse gliomas are a type of brain tumour afflicting adults and children, often with a fatal outcome. An accurate diagnosis is required to give patients correct treatment and for the allocation of homogeneous diagnoses into clinical trials. Diagnosis is historically based upon the visual appearance of the tumour in a microscope, but is nowadays also complemented by molecular analyses of how the tumour cells' DNA has altered. One aspect that has gained considerable interest is the so-called DNA methylation pattern of the tumour. The pattern is a sort of bar code for the tumour, and this bar code differs for various tumour types. As such, the methylation pattern can be used for the diagnosis of tumours and stratification into methylation subclasses. Here, we review the utility of DNA methylation as a diagnostic tool in diffuse gliomas and considerations for its use. Diffuse gliomas cause significant morbidity across all age groups, despite decades of intensive research efforts. Here, we review the differences in diffuse gliomas in adults and children, as well as the World Health Organisation (WHO) 2021 classification of these tumours. We explain how DNA methylation-based classification works and list the methylation-based tumour types and subclasses for adult and paediatric diffuse gliomas. The benefits and utility of methylation-based classification in diffuse gliomas demonstrated to date are described. This entails the identification of novel tumour types/subclasses, patient stratification and targeted treatment/clinical management, and alterations in the clinical diagnosis in favour of the methylation-based over the histopathological diagnosis. Finally, we address several considerations regarding the use of DNA methylation profiling as a diagnostic tool, e.g., the threshold of the classifier, the calibrated score, tumour cell content and intratumour heterogeneity.
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