| 1. |
- Backman, Samuel, et al.
(författare)
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Detection of Somatic Mutations in Gastroenteropancreatic Neuroendocrine Tumors Using Targeted Deep Sequencing
- 2017
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Ingår i: Anticancer Research. - : Anticancer Research USA Inc.. - 0250-7005 .- 1791-7530. ; 37:2, s. 705-712
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Tidskriftsartikel (refereegranskat)abstract
- Mutations affecting the mechanistic target of rapamycin (MTOR) signalling pathway are frequent in human cancer and have been identified in up to 15% of pancreatic neuroendocrine tumours (NETs). Grade A evidence supports the efficacy of MTOR inhibition with everolimus in pancreatic NETs. Although a significant proportion of patients experience disease stabilization, only a minority will show objective tumour responses. It has been proposed that genomic mutations resulting in activation of MTOR signalling could be used to predict sensitivity to everolimus.PATIENTS AND METHODS: Patients with NETs that underwent treatment with everolimus at our Institution were identified and those with available tumour tissue were selected for further analysis. Targeted next-generation sequencing (NGS) was used to re-sequence 22 genes that were selected on the basis of documented involvement in the MTOR signalling pathway or in the tumourigenesis of gastroenterpancreatic NETs. Radiological responses were documented using Response Evaluation Criteria in Solid Tumours.RESULTS: Six patients were identified, one had a partial response and four had stable disease. Sequencing of tumour tissue resulted in a median sequence depth of 667.1 (range=404-1301) with 1-fold coverage of 95.9-96.5% and 10-fold coverage of 87.6-92.2%. A total of 494 genetic variants were discovered, four of which were identified as pathogenic. All pathogenic variants were validated using Sanger sequencing and were found exclusively in menin 1 (MEN1) and death domain associated protein (DAXX) genes. No mutations in the MTOR pathway-related genes were observed.CONCLUSION: Targeted NGS is a feasible method with high diagnostic yield for genetic characterization of pancreatic NETs. A potential association between mutations in NETs and response to everolimus should be investigated by future studies.
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| 2. |
- Backman, Samuel, et al.
(författare)
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Global DNA Methylation Analysis Identifies Two Discrete clusters of Pheochromocytoma with Distinct Genomic and Genetic Alterations
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Pheochromocytomas and paragangliomas (PPGLs) are rare and frequently heritable neural-crest derived tumours arising from the adrenal medulla or extra-adrenal chromaffin cells respectively. The majority of PPGL tumours are benign and do not recur with distant metastases. However, a sizeable fraction of these tumours secrete vasoactive catecholamines into the circulation causing a variety of symptoms including hypertension, palpitations and diaphoresis. The genetic landscape of PPGL has been well characterized and more than a dozen genes have been described as recurrently mutated. Recent studies of DNA-methylation have revealed distinct clusters of PPGL that share DNA methylation patterns and driver mutations, as well as identified potential biomarkers for malignancy. However, these findings have not been adequately validated in independent cohorts. In this study we use an array-based genome-wide approach to study the methylome of 39 PPGL and 4 normal adrenal medullae. We identified two distinct clusters of tumours characterized by different methylation patterns and different driver mutations. Moreover, we identify genes that are differentially methylated between tumour subcategories, and between tumours and normal tissue.
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| 3. |
- Backman, Samuel, 1994-
(författare)
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Molecular studies of endocrine tumors : Insights from genetics and epigenetics
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Endocrine tumors may be benign or malignant and may occur in any of the hormone producing tissues. They share several biological characteristics, including a low mutation-burden, and may co-occur in several hereditary tumor syndromes. The aim of this thesis was to identify genetic and epigenetic aberrations in endocrine tumors.In paper I we performed a comprehensive DNA methylation analysis of 39 pheochromocytomas/paragangliomas as well as 4 normal adrenal medullae on the HumanMethylation27 BeadChip array. We validated two previously described clusters based on DNA methylation with distinct genetic associations.In Paper II we performed a transcriptomic analysis of 15 aldosterone producing adenomas. CTNNB1-mutated tumors were found to form a distinct subgroup based on gene expression and to share gene expression similarities with non-aldosterone producing adrenocortical tumors with CTNNB1 mutations, including overexpression of AFF3 and ISM1.In paper III we used whole genome sequencing to identify germline genetic variants in 14 patients with Multiple Endocrine Neoplasia type 1 previously found to be wildtype for the MEN1 gene on routine clinical testing. Three patients were found to carry previously undetected MEN1 mutations. Two patients were confirmed to have phenocopies caused by variants affecting CASR or CDC73. In total 9/14 patients were not found to have a disease-causing germline variant, suggesting that the syndrome may in some cases be due to chance co-occurrence of several sporadic tumors.In paper IV RNA-Seq and whole genome sequencing of a cohort of SI-NETs selected on the basis of unusually short or long survival was performed in order to identify disease causing genes and potential prognostic factors. We confirmed known genetic aberrations and found rare variants in known cancer driver genes. Based on gene expression two clusters that differ in prognosis were detected. Moreover, through integration of copy number variation data and gene expression, we identied novel potential disease causing genes.
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| 4. |
- Backman, Samuel, et al.
(författare)
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Potential prognostic markers and candidate genetic drivers in small intestine neuroendocrine tumours
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundSmall intestinal neuroendocrine tumours (SI-NETs) are the most common tumour of the small intestine. The disease often has a favourable outcome with long survival even in the context of metastatic disease. However, some patients fare worse and succumb to the disease soon after diagnosis despite similar stage and grade. Molecular prognostic markers are lacking. The most common genetic aberration is loss of chromosome 18q, although the oncogenic mechanism of this is unknown. The only recurrently mutated gene is CDKN1B, which is mutated in 9% of cases.AimsTo identify molecular derangements in SI-NETs and identify potential prognostic markers.MethodsForty tumour samples from thirty patients with unusually long or unusually short survival after diagnosis were subjected to whole genome sequencing. Twenty of the samples were also included for RNA Sequencing.ResultsIn addition to mutations in CDKN1B we find rare variants in known cancer genes including NF1, MAX and SPEN. Unsupervised clustering based on gene expression resulted in two clusters with prognostic significance. We identify potential prognostic markers based on gene expression. Finally, we identify genes whose expression is affected by the most common copy number variations in these tumours, including SOCS6 on chromosome 18 and ATM on chromosome 11.
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| 5. |
- Backman, Samuel, et al.
(författare)
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The Evolutionary History of Metastatic Pancreatic Neuroendocrine Tumours Reveals a Therapy Driven Route to High-Grade Transformation.
- 2024
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Ingår i: medRxiv : the preprint server for health sciences.
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Tidskriftsartikel (refereegranskat)abstract
- Tumour evolution with acquisition of more aggressive disease characteristics is a hallmark of disseminated cancer. Metastatic pancreatic neuroendocrine tumours (PanNETs) in particular, show frequent progression from a low/intermediate to a high-grade disease. To understand the molecular mechanisms underlying this phenomenon, we performed multi-omics analysis of 32 longitudinal samples from six metastatic PanNET patients. Following MEN1 inactivation, PanNETs exhibit genetic heterogeneity on both spatial and temporal dimensions with parallel and convergent tumuor evolution involving the ATRX/DAXX and mTOR pathways. Following alkylating chemotherapy treatment, some PanNETs develop mismatch repair deficiency and acquire a hypermutator phenotype. This DNA hypermutation phenotype was only found in cases that also showed transformation into a high-grade PanNET. Overall, our findings contribute to broaden the understanding of metastatic PanNET, and suggests that therapy driven disease evolution is an important hallmark of this disease.
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| 6. |
- Backman, Samuel, et al.
(författare)
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Whole genome sequencing of apparently mutation-negative MEN1 patients
- 2020
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Ingår i: European Journal of Endocrinology. - : Oxford University Press (OUP). - 0804-4643 .- 1479-683X. ; 182:1, s. 35-45
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:Multiple Endocrine Neoplasia type 1 (MEN1) is an autosomal dominant syndrome usually caused by loss-of-function mutations in the MEN1-gene. However, a minority of patients who fulfill the criteria for MEN1 are not found to harbor MEN1-mutations. Besides, some of these individuals, present with a subtly different phenotype suggestive of sporadic disease. The aim of the present study was to investigate the genetic architecture of mutation-negative MEN1. DESIGN:Fourteen patients with a clinical diagnosis (n=13) or suspicion (n=1) of MEN1 who had negative genetic screening of the MEN1 gene were included. METHODS:Constitutional DNA from the included patients, as well as tumor DNA from six of the patients, was subjected to whole genome sequencing. Constitutional variants were filtered against population databases and somatic variants were studied under a tumor-suppressor model. RESULTS:Three patients carried pathogenic variants (two splice-site variants, one missense variant) in MEN1 that had not been detected during routine clinical sequencing, one patient carried a pathogenic variant in CASR and one patient carried a gross deletion on chromosome 1q which included the CDC73 gene. Analysis of matched tumor DNA from six patients without mutations did not detect any recurrent genes fulfilling Knudson's two-hit model. CONCLUSION:These results highlight the possibility of germline mutations being missed in routine screening, the importance of considering phenocopies in atypical or mutation-negative cases. The absence of apparent disease-causing mutations suggests that a fraction of MEN1 mutation negative MEN1 cases may be due to the chance occurrence of several endocrine tumors in one patient.
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| 7. |
- Crona, Joakim, et al.
(författare)
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RNA-Sequencing Analysis of Adrenocortical Carcinoma, Pheochromocytoma and Paraganglioma from a Pan-Cancer Perspective
- 2018
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Ingår i: Cancers. - : MDPI. - 2072-6694. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Adrenocortical carcinoma (ACC) and pheochromocytoma and paraganglioma (PPGL) are defined by clinicopathological criteria and can be further sub-divided based on different molecular features. Whether differences between these molecular subgroups are significant enough to re-challenge their current clinicopathological classification is currently unknown. It is also not fully understood to which other cancers ACC and PPGL show similarity to. To address these questions, we included recent RNA-Seq data from the Cancer Genome Atlas (TCGA) and Therapeutically Applicable Research to Generate Effective Treatments (TARGET) datasets. Two bioinformatics pipelines were used for unsupervised clustering and principal components analysis. Results were validated using consensus clustering model and interpreted according to previous pan-cancer experiments. Two datasets consisting of 3319 tumors from 35 disease categories were studied. Consistent with the current classification, ACCs clustered as a homogenous group in a pan-cancer context. It also clustered close to neural crest derived tumors, including gliomas, neuroblastomas, pancreatic neuroendocrine tumors, and PPGLs. Contrary, some PPGLs mixed with pancreatic neuroendocrine tumors or neuroblastomas. Thus, our unbiased gene-expression analysis of PPGL did not overlap with their current clinicopathological classification. These results emphasize some importances of the shared embryological origin of these tumors, all either related or close to neural crest tumors, and opens for investigation of a complementary categorization based on gene-expression features.
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| 8. |
- Crona, Joakim, et al.
(författare)
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Spatiotemporal Heterogeneity Characterizes the Genetic Landscape of Pheochromocytoma and Defines Early Events in Tumorigenesis.
- 2015
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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 21:19, s. 4451-4460
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Pheochromocytoma and paraganglioma (PPGL) patients display heterogeneity in the clinical presentation and underlying genetic cause. The degree of inter- and intratumor genetic heterogeneity has not yet been defined.EXPERIMENTAL DESIGN: In PPGLs from 94 patients, we analyzed LOH, copy-number variations, and mutation status of SDHA, SDHB, SDHC, SDHD, SDHAF2, VHL, EPAS1, NF1, RET, TMEM127, MAX, and HRAS using high-density SNP array and targeted deep sequencing, respectively. Genetic heterogeneity was determined through (i) bioinformatics analysis of individual samples that estimated absolute purity and ploidy from SNP array data and (ii) comparison of paired tumor samples that allowed reconstruction of phylogenetic trees.RESULTS: Mutations were found in 61% of the tumors and correlated with specific patterns of somatic copy-number aberrations (SCNA) and degree of nontumoral cell admixture. Intratumor genetic heterogeneity was observed in 74 of 136 samples using absolute bioinformatics estimations and in 22 of 24 patients by comparison of paired samples. In addition, a low genetic concordance was observed between paired primary tumors and distant metastases. This allowed for reconstructing the life history of individual tumors, identifying somatic mutations as well as copy-number loss of 3p and 11p (VHL subgroup), 1p (Cluster 2), and 17q (NF1 subgroup) as early events in PPGL tumorigenesis.CONCLUSIONS: Genomic landscapes of PPGL are specific to mutation subtype and characterized by genetic heterogeneity both within and between tumor lesions of the same patient.
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| 9. |
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| 10. |
- Paulsson, Johan O., et al.
(författare)
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Whole‐genome sequencing of synchronous thyroid carcinomas identifies aberrant DNA repair in thyroid cancer dedifferentiation
- 2020
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Ingår i: Journal of Pathology. - : Wiley. - 0022-3417 .- 1096-9896. ; 250:2, s. 183-194
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Tidskriftsartikel (refereegranskat)abstract
- The genetics underlying thyroid cancer dedifferentiation is only partly understood and has not yet been characterised using comprehensive pan‐genomic analyses. We investigated a unique case with synchronous follicular thyroid carcinoma (FTC), poorly differentiated thyroid carcinoma (PDTC), and anaplastic thyroid carcinoma (ATC), as well as regional lymph node metastases from the PDTC and ATC from a single patient using whole‐genome sequencing (WGS). The FTC displayed mutations in CALR, RB1, and MSH2, and the PDTC exhibited mutations in TP53, DROSHA, APC, TERT, and additional DNA repair genes – associated with an immense increase in sub‐clonal somatic mutations. All components displayed an overrepresentation of C>T transitions with associated microsatellite instability (MSI) in the PDTC and ATC, with borderline MSI in the FTC. Clonality analyses pinpointed a shared ancestral clone enriched for mutations in TP53‐associated regulation of DNA repair and identified important sub‐clones for each tumour component already present in the corresponding preceding lesion. This genomic characterisation of the natural progression of thyroid cancer reveals several novel genes of interest for future studies. Moreover, the findings support the theory of a stepwise dedifferentiation process and suggest that defects in DNA repair could play an important role in the clonal evolution of thyroid cancer.
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