| 1. |
- Christofer Juhlin, C., et al.
(författare)
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Whole-exome sequencing defines the mutational landscape of pheochromocytoma and identifies KMT2D as a recurrently mutated gene
- 2015
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Ingår i: Genes, Chromosomes and Cancer. - : Wiley: 12 months. - 1045-2257 .- 1098-2264. ; 54:9, s. 542-554
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Tidskriftsartikel (refereegranskat)abstract
- As subsets of pheochromocytomas (PCCs) lack a defined molecular etiology, we sought to characterize the mutational landscape of PCCs to identify novel gene candidates involved in disease development. A discovery cohort of 15 PCCs wild type for mutations in PCC susceptibility genes underwent whole-exome sequencing, and an additional 83 PCCs served as a verification cohort for targeted sequencing of candidate mutations. A low rate of nonsilent single nucleotide variants (SNVs) was detected (6.1/sample). Somatic HRAS and EPAS1 mutations were observed in one case each, whereas the remaining 13 cases did not exhibit variants in established PCC genes. SNVs aggregated in apoptosis-related pathways, and mutations in COSMIC genes not previously reported in PCCs included ZAN, MITF, WDTC1, and CAMTA1. Two somatic mutations and one constitutional variant in the well-established cancer gene lysine (K)-specific methyltransferase 2D (KMT2D, MLL2) were discovered in one sample each, prompting KMT2D screening using focused exome-sequencing in the verification cohort. An additional 11 PCCs displayed KMT2D variants, of which two were recurrent. In total, missense KMT2D variants were found in 14 (11 somatic, two constitutional, one undetermined) of 99 PCCs (14%). Five cases displayed somatic mutations in the functional FYR/SET domains of KMT2D, constituting 36% of all KMT2D-mutated PCCs. KMT2D expression was upregulated in PCCs compared to normal adrenals, and KMT2D overexpression positively affected cell migration in a PCC cell line. We conclude that KMT2D represents a recurrently mutated gene with potential implication for PCC development. (c) 2015 The Authors. Genes, Chromosomes and Cancer Published by Wiley Periodicals, Inc.
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| 3. |
- Kugelberg, Johan, et al.
(författare)
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Role of SDHAF2 and SDHD in von Hippel-Lindau Associated Pheochromocytomas
- 2014
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Ingår i: World Journal of Surgery. - : Springer Verlag (Germany). - 0364-2313 .- 1432-2323. ; 38:3, s. 724-732
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Tidskriftsartikel (refereegranskat)abstract
- Background Pheochromocytomas (PCCs) develop from the adrenal medulla and are often part of a hereditary syndrome such as von Hippel-Lindau (VHL) syndrome. In VHL, only about 30 % of patients with a VHL missense mutation develop PCCs. Thus, additional genetic events leading to formation of such tumors in patients with VHL syndrome are sought. SDHAF2 (previously termed SDH5) and SDHD are both located on chromosome 11q and are required for the function of mitochondrial complex II. While SDHAF2 has been shown to be mutated in patients with paragangliomas (PGLs), SDHD mutations have been found both in patients with PCCs and in patients with PGLs. Materials and methods Because loss of 11q is a common event in VHL-associated PCCs, we aimed to investigate whether SDHAF2 and SDHD are targets. In the present study, 41 VHL-associated PCCs were screened for mutations and loss of heterozygosity (LOH) in SDHAF2 or SDHD. Promoter methylation, as well as mRNA expression of SDHAF2 and SDHD, was studied. In addition, immunohistochemistry (IHC) of SDHB, known to be a universal marker for loss of any part the SDH complex, was conducted. Results and conclusions LOH was found in more than 50 % of the VHL-associated PCCs, and was correlated with a significant decrease (p less than 0.05) in both SDHAF2 and SDHD mRNA expression, which may be suggestive of a pathogenic role. However, while SDHB protein expression as determined by IHC in a small cohort of tumors was lower in PCCs than in the surrounding adrenal cortex, there was no obvious correlation with LOH or the level of SDHAF2/SDHD mRNA expression. In addition, the lack of mutations and promoter methylation in the investigated samples indicates that other events on chromosome 11 might be involved in the development of PCCs in association with VHL syndrome.
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| 4. |
- Stenman, Adam, et al.
(författare)
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HRAS mutation prevalence and associated expression patterns in pheochromocytoma
- 2016
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Ingår i: Genes, Chromosomes and Cancer. - : WILEY-BLACKWELL. - 1045-2257 .- 1098-2264. ; 55:5, s. 452-459
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Tidskriftsartikel (refereegranskat)abstract
- Pheochromocytomas (PCC) and abdominal paragangliomas (PGL) display a highly diverse genetic background and recent gene expression profiling studies have shown that PCC and PGL (together PPGL) alter either kinase signaling pathways or the pseudo-hypoxia response pathway dependent of the genetic composition. Recurrent mutations in the Harvey rat sarcoma viral oncogene homolog (HRAS) have recently been verified in sporadic PPGLs. In order to further establish the HRAS mutation frequency and to characterize the associated expression profiles of HRAS mutated tumors, 156 PPGLs for exon 2 and 3 hotspot mutations in the HRAS gene was screened, and compared with microarray-based gene expression profiles for 93 of the cases. The activating HRAS mutations G13R, Q61R, and Q61K were found in 10/142 PCC (7.0%) and a Q61L mutation was revealed in 1/14 PGL (7.1%). All HRAS mutated cases included in the mRNA expression profiling grouped in Cluster 2, and 21 transcripts were identified as altered when comparing the mutated tumors with 91 HRAS wild-type PPGL. Somatic HRAS mutations were not revealed in cases with known PPGL susceptibility gene mutations and all HRAS mutated cases were benign. The HRAS mutation prevalence of all PPGL published up to date is 5.2% (49/950), and 8.8% (48/548) among cases without a known PPGL susceptibility gene mutation. The findings support a role of HRAS mutations as a somatic driver event in benign PPGL without other known susceptibility gene mutations. HRAS mutated PPGL cluster together with NF1- and RET-mutated tumors associated with activation of kinase-signaling pathways.
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| 5. |
- Welander, Jenny, et al.
(författare)
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Frequent EPAS1/HIF2 alpha exons 9 and 12 mutations in non-familial pheochromocytoma
- 2014
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Ingår i: Endocrine-Related Cancer. - : BioScientifica. - 1351-0088 .- 1479-6821. ; 21:3, s. 495-504
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Tidskriftsartikel (refereegranskat)abstract
- Pheochromocytomas are neuroendocrine tumors arising from the adrenal medulla. While heritable mutations are frequently described, less is known about the genetics of sporadic pheochromocytoma. Mutations in genes involved in the cellular hypoxia response have been identified in tumors, and recently EPAS1, encoding HIF2 alpha, has been revealed to be a new gene involved in the pathogenesis of pheochromocytoma and abdominal paraganglioma. The aim of this study was to further characterize EPAS1 alterations in non-familial pheochromocytomas. Tumor DNA from 42 adrenal pheochromocytoma cases with apparently sporadic presentation, without known hereditary mutations in predisposing genes, were analyzed for mutations in EPAS1 by sequencing of exons 9 and 12, which contain the two hydroxylation sites involved in HIF2a degradation, and also exon 2. In addition, the copy number at the EPAS1 locus as well as transcriptome-wide gene expression were studied by DNA and RNA microarray analyses, respectively. We identified six missense EPAS1 mutations, three in exon 9 and three in exon 12, in five of 42 pheochromocytomas (12%). The mutations were both somatic and constitutional, and had no overlap in 11 cases (26%) with somatic mutations in NF1 or RET. One sample had two different EPAS1 mutations, shown by cloning to occur in cis, possibly indicating a novel mechanism of HIF2a stabilization through inactivation of both hydroxylation sites. One of the tumors with an EPAS1 mutation also had a gain in DNA copy number at the EPAS1 locus. All EPAS1-mutated tumors displayed a pseudo-hypoxic gene expression pattern, indicating an oncogenic role of the identified mutations.
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| 6. |
- Welander, Jenny, et al.
(författare)
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Integrative genomics reveals frequent somatic NF1 mutations in sporadic pheochromocytomas
- 2012
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP): Policy B. - 0964-6906 .- 1460-2083. ; 21:26, s. 5406-5416
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Tidskriftsartikel (refereegranskat)abstract
- Pheochromocytomas are neuroendocrine tumors of the adrenal medulla which can occur either sporadically or in the context of hereditary tumor syndromes. Whereas the genetic background of hereditary pheochromocytomas is becoming rather well-defined, very little is known about the more common sporadic form of the disease which constitutes approximate to 70 of all cases. In this study, we elucidate some of the molecular mechanisms behind sporadic pheochromocytoma by performing a comprehensive analysis of copy number alterations, gene expression, promoter methylation and somatic mutations in the genes RET, VHL, NF1, SDHA, SDHB, SDHC, SDHD, SDHAF2, KIF1B, TMEM127 and MAX, which have been associated with hereditary pheochromocytoma or paraganglioma. Our genomic and genetic analyses of 42 sporadic pheochromocytomas reveal that a large proportion (83) has an altered copy number in at least one of the known susceptibility genes, often in association with an altered messenger RNA (mRNA) expression. Specifically, 11 sporadic tumors (26) displayed a loss of one allele of the NF1 gene, which significantly correlated with a reduced NF1 mRNA expression. Subsequent sequencing of NF1 mRNA, followed by confirmation in the corresponding genomic DNA (gDNA), revealed somatic truncating mutations in 10 of the 11 tumors with NF1 loss. Our results thus suggest that the NF1 gene constitutes the most frequent (24) target of somatic mutations so far known in sporadic pheochromocytomas.
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| 7. |
- Welander, Jenny, et al.
(författare)
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Rare Germline Mutations Identified by Targeted Next-Generation Sequencing of Susceptibility Genes in Pheochromocytoma and Paraganglioma
- 2014
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 99:7, s. E1352-E1360
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Tidskriftsartikel (refereegranskat)abstract
- Context: Pheochromocytomas and paragangliomas have a highly diverse genetic background, with a third of the cases carrying a germline mutation in 1 of 14 identified genes. Objective: This study aimed to evaluate next-generation sequencing for more efficient genetic testing of pheochromocytoma and paraganglioma and to establish germline and somatic mutation frequencies for all known susceptibility genes. Design: A targeted next-generation sequencing approach on an Illumina MiSeq instrument was used for a mutation analysis in 86 unselected pheochromocytoma and paraganglioma tumor samples. The study included the genes EGLN1, EPAS1, KIF1B beta, MAX, MEN1, NF1, RET, SDHA, SDHB, SDHC, SDHD, SDHAF2, TMEM127, and VHL. Results were verified in tumor and constitutional DNA with Sanger sequencing. Results: In all cases with clinical syndromes or known germline mutations, a mutation was detected in the expected gene. Among 68 nonfamilial tumors, 32 mutations were identified in 28 of the samples (41%), including germline mutations in EGLN1, KIF1B beta, SDHA, SDHB, and TMEM127 and somatic mutations in EPAS1, KIF1B beta, MAX, NF1, RET, and VHL, including one double monoallelic EPAS1 mutation. Conclusions: Targeted next-generation sequencing proved to be fast and cost effective for the genetic analysis of pheochromocytoma and paraganglioma. More than half of the tumors harbored mutations in the investigated genes. Notably, 7% of the apparently sporadic cases carried germline mutations, highlighting the importance of comprehensive genetic testing. KIF1B beta, which previously has not been investigated in a large cohort, appears to be an equally important tumor suppressor as MAX and TMEM127 and could be considered for genetic testing of these patients.
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