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Jenny Welander, Peter Söderkvist and Oliver Gimm

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine tumors of the adrenal glands and the sympathetic and parasympathetic paraganglia. They can occur sporadically or as a part of different hereditary tumor syndromes. About 30% of PCCs and PGLs are currently believed to be caused by germline mutations and several novel susceptibility genes have recently been discovered. The clinical presentation, including localization, malignant potential, and age of onset, varies depending on the genetic background of the tumors. By reviewing more than 1700 reported cases of hereditary PCC and PGL, a thorough summary of the genetics and clinical features of these tumors is given, both as part of the classical syndromes such as multiple endocrine neoplasia type 2 (MEN2), von Hippel–Lindau disease, neurofibromatosis type 1, and succinate dehydrogenase-related PCC–PGL and within syndromes associated with a smaller fraction of PCCs/PGLs, such as Carney triad, Carney–Stratakis syndrome, and MEN1. The review also covers the most recently discovered susceptibility genes including KIF1Bβ, EGLN1/PHD2, SDHAF2, TMEM127, SDHA, and MAX, as well as a comparison with the sporadic form. Further, the latest advances in elucidating the cellular pathways involved in PCC and PGL development are discussed in detail. Finally, an algorithm for genetic testing in patients with PCC and PGL is proposed.

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Ravi Kumar Dutta, Peter Söderkvist and Oliver Gimm

Hypertension is a common medical condition and affects approximately 20% of the population in developed countries. Primary aldosteronism is the most common form of secondary hypertension and affects 8–13% of patients with hypertension. The two most common causes of primary aldosteronism are aldosterone-producing adenoma and bilateral adrenal hyperplasia. Familial hyperaldosteronism types I, II and III are the known genetic syndromes, in which both adrenal glands produce excessive amounts of aldosterone. However, only a minority of patients with primary aldosteronism have one of these syndromes. Several novel susceptibility genes have been found to be mutated in aldosterone-producing adenomas: KCNJ5, ATP1A1, ATP2B3, CTNNB1, CACNA1D, CACNA1H and ARMC5. This review describes the genes currently known to be responsible for primary aldosteronism, discusses the origin of aldosterone-producing adenomas and considers the future clinical implications based on these novel insights.

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Jenny Welander, Peter Söderkvist and Oliver Gimm

Patients suffering from the neurofibromatosis type 1 syndrome, which is caused by germline mutations in the NF1 gene, have a tiny but not negligible risk of developing pheochromocytomas. It is, therefore, of interest that the NF1 gene has recently been revealed to carry somatic, inactivating mutations in a total of 35 (21.7%) of 161 sporadic pheochromocytomas in two independent tumor series. A majority of the tumors in both studies displayed loss of heterozygosity at the NF1 locus and a low NF1 mRNA expression. In view of previous findings that many sporadic pheochromocytomas cluster with neurofibromatosis type 1 syndrome-associated pheochromocytomas instead of forming clusters of their own, NF1 inactivation appears to be an important step in the pathogenesis of a large number of sporadic pheochromocytomas. A literature and public mutation database review has revealed that pheochromocytomas are among those human neoplasms in which somatic NF1 alterations are most frequent.

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Jenny Welander, Adam Andreasson, Michael Brauckhoff, Martin Bäckdahl, Catharina Larsson, Oliver Gimm and Peter Söderkvist

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 HIF2α, 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 HIF2α 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 HIF2α 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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Ravi Kumar Dutta, Jenny Welander, Michael Brauckhoff, Martin Walz, Piero Alesina, Thomas Arnesen, Peter Söderkvist and Oliver Gimm

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Stefan Karger, Carl Weidinger, Kerstin Krause, Sien-Yi Sheu, Thomas Aigner, Oliver Gimm, Kurt-Werner Schmid, Henning Dralle and Dagmar Fuhrer

The forkhead box transcription factor FOXO3a has recently been identified as central mediator of the cellular response to oxidative stress inducing cell cycle arrest or apoptosis. The aim of our study was to investigate the regulation of FOXO3a in the thyroid and to determine whether alterations in FOXO3a activity occur in thyroid carcinogenesis. In vitro, we demonstrate that FOXO3a activity is negatively regulated by the PI3K/Akt cascade promoting increased phosphorylation and cytoplasmatic accumulation of FOXO3a with decreased transcription of the target genes p27kip (CDKN1B) and Bim (BCL2L11), but increased expression of GADD45A. By contrast, we show that H2O2 exposure activates FOXO3a in thyrocytes with JNK (MAPK8)-mediated nuclear accumulation of FOXO3a and increased expression of the cell cycle arrest genes p27kip and GADD45A. In vivo, we observed a marked cytoplasmatic accumulation of FOXO3a in differentiated thyroid cancers versus an exclusive nuclear accumulation in follicular adenoma and normal thyroid tissue. Moreover, this cytosolic accumulation of FOXO3a correlated with an increased phospho-Akt expression in thyroid malignancies and was accompanied by decreased expression of the FOXO targets p27kip and Bim and an increase in GADD45A mRNA expression in the thyroid cancers. Our data suggest FOXO3a as a novel player of cellular stress response in the thyroid, mediating the thyrocyte's fate either to survive or to undergo apoptosis. Furthermore, PI3K-dependent FOXO3a inactivation may be a novel pathomechanism for the escape from apoptosis in thyroid cancer cells, in particular in follicular thyroid carcinoma.

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Michael A Hahn, Viive M Howell, Anthony J Gill, Adele Clarkson, Graham Weaire-Buchanan, Bruce G Robinson, Leigh Delbridge, Oliver Gimm, Wolfgang D Schmitt, Bin T Teh and Deborah J Marsh

The tumor suppressor HRPT2/CDC73 is mutated in constitutive DNA from patients with the familial disorder hyperparathyroidism–jaw tumor syndrome and in ∼70% of all parathyroid carcinomas. In a number of HRPT2 mutant tumors however, expression of the encoded protein parafibromin is lost in the absence of a clear second event such as HRPT2 allelic loss or the presence of a second mutation in this tumor suppressor gene. We sought to determine whether hypermethylation of a 713 bp CpG island extending 648 nucleotides upstream of the HRPT2 translational start site and 65 nucleotides into exon 1 might be a mechanism contributing to the loss of expression of parafibromin in parathyroid tumors. Furthermore, we asked whether mutations might be present in the 5′-untranslated region (5′-UTR) of HRPT2. We investigated a pool of tissue from 3 normal parathyroid glands, as well as 15 individual parathyroid tumor samples including 6 tumors with known HRPT2 mutations, for hypermethylation of the HRPT2 CpG island. Methylation was not identified in any specimens despite complete loss of parafibromin expression in two parathyroid carcinomas with a single detectable HRPT2 mutation and retention of the wild-type HRPT2 allele. Furthermore, no mutations of a likely pathogenic nature were identified in the 5′-UTR of HRPT2. These data strongly suggest that alternative mechanisms such as mutation in HRPT2 intronic regions, additional epigenetic regulation such as histone modifications, or other regulatory inactivation mechanisms such as targeting by microRNAs may play a role in the loss of parafibromin expression.

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Hartmut P Neumann, William F Young Jr, Tobias Krauss, Jean-Pierre Bayley, Francesca Schiavi, Giuseppe Opocher, Carsten C Boedeker, Amit Tirosh, Frederic Castinetti, Juri Ruf, Dmitry Beltsevich, Martin Walz, Harald-Thomas Groeben, Ernst von Dobschuetz, Oliver Gimm, Nelson Wohllk, Marija Pfeifer, Delmar M Lourenço Jr, Mariola Peczkowska, Attila Patocs, Joanne Ngeow, Özer Makay, Nalini S Shah, Arthur Tischler, Helena Leijon, Gianmaria Pennelli, Karina Villar Gómez de las Heras, Thera P Links, Birke Bausch and Charis Eng

Although the authors of the present review have contributed to genetic discoveries in the field of pheochromocytoma research, we can legitimately ask whether these advances have led to improvements in the diagnosis and management of patients with pheochromocytoma. The answer to this question is an emphatic Yes! In the field of molecular genetics, the well-established axiom that familial (genetic) pheochromocytoma represents 10% of all cases has been overturned, with >35% of cases now attributable to germline disease-causing mutations. Furthermore, genetic pheochromocytoma can now be grouped into five different clinical presentation types in the context of the ten known susceptibility genes for pheochromocytoma-associated syndromes. We now have the tools to diagnose patients with genetic pheochromocytoma, identify germline mutation carriers and to offer gene-informed medical management including enhanced surveillance and prevention. Clinically, we now treat an entire family of tumors of the paraganglia, with the exact phenotype varying by specific gene. In terms of detection and classification, simultaneous advances in biochemical detection and imaging localization have taken place, and the histopathology of the paraganglioma tumor family has been revised by immunohistochemical-genetic classification by gene-specific antibody immunohistochemistry. Treatment options have also been substantially enriched by the application of minimally invasive and adrenal-sparing surgery. Finally and most importantly, it is now widely recognized that patients with genetic pheochromocytoma/paraganglioma syndromes should be treated in specialized centers dedicated to the diagnosis, treatment and surveillance of this rare neoplasm.

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Tobias Krauss, Alfonso Massimiliano Ferrara, Thera P Links, Ulrich Wellner, Irina Bancos, Andrey Kvachenyuk, Karina Villar Gómez de las Heras, Marina Y Yukina, Roman Petrov, Garrett Bullivant, Laura von Duecker, Swati Jadhav, Ursula Ploeckinger, Staffan Welin, Camilla Schalin-Jäntti, Oliver Gimm, Marija Pfeifer, Joanne Ngeow, Kornelia Hasse-Lazar, Gabriela Sansó, Xiaoping Qi, M Umit Ugurlu, Rene E Diaz, Nelson Wohllk, Mariola Peczkowska, Jens Aberle, Delmar M Lourenço Jr, Maria A A Pereira, Maria C B V Fragoso, Ana O Hoff, Madson Q Almeida, Alice H D Violante, Ana R P Quidute, Zhewei Zhang, Mònica Recasens, Luis Robles Díaz, Tada Kunavisarut, Taweesak Wannachalee, Sirinart Sirinvaravong, Eric Jonasch, Simona Grozinsky-Glasberg, Merav Fraenkel, Dmitry Beltsevich, Viacheslav I Egorov, Dirk Bausch, Matthias Schott, Nikolaus Tiling, Gianmaria Pennelli, Stefan Zschiedrich, Roland Därr, Juri Ruf, Timm Denecke, Karl-Heinrich Link, Stefania Zovato, Ernst von Dobschuetz, Svetlana Yaremchuk, Holger Amthauer, Özer Makay, Attila Patocs, Martin K Walz, Tobias B Huber, Jochen Seufert, Per Hellman, Raymond H Kim, Ekaterina Kuchinskaya, Francesca Schiavi, Angelica Malinoc, Nicole Reisch, Barbara Jarzab, Marta Barontini, Andrzej Januszewicz, Nalini Shah, William F Young Jr, Giuseppe Opocher, Charis Eng, Hartmut P H Neumann and Birke Bausch

Pancreatic neuroendocrine tumors (PanNETs) are rare in von Hippel–Lindau disease (VHL) but cause serious morbidity and mortality. Management guidelines for VHL-PanNETs continue to be based on limited evidence, and survival data to guide surgical management are lacking. We established the European-American-Asian-VHL-PanNET-Registry to assess data for risks for metastases, survival and long-term outcomes to provide best management recommendations. Of 2330 VHL patients, 273 had a total of 484 PanNETs. Median age at diagnosis of PanNET was 35 years (range 10–75). Fifty-five (20%) patients had metastatic PanNETs. Metastatic PanNETs were significantly larger (median size 5 vs 2 cm; P < 0.001) and tumor volume doubling time (TVDT) was faster (22 vs 126 months; P = 0.001). All metastatic tumors were ≥2.8 cm. Codons 161 and 167 were hotspots for VHL germline mutations with enhanced risk for metastatic PanNETs. Multivariate prediction modeling disclosed maximum tumor diameter and TVDT as significant predictors for metastatic disease (positive and negative predictive values of 51% and 100% for diameter cut-off ≥2.8 cm, 44% and 91% for TVDT cut-off of ≤24 months). In 117 of 273 patients, PanNETs >1.5 cm in diameter were operated. Ten-year survival was significantly longer in operated vs non-operated patients, in particular for PanNETs <2.8 cm vs ≥2.8 cm (94% vs 85% by 10 years; P = 0.020; 80% vs 50% at 10 years; P = 0.030). This study demonstrates that patients with PanNET approaching the cut-off diameter of 2.8 cm should be operated. Mutations in exon 3, especially of codons 161/167 are at enhanced risk for metastatic PanNETs. Survival is significantly longer in operated non-metastatic VHL-PanNETs.