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Free access

Giampaolo Trivellin, Ricardo R Correa, Maria Batsis, Fabio R Faucz, Prashant Chittiboina, Ivana Bjelobaba, Darwin O Larco, Martha Quezado, Adrian F Daly, Stanko S Stojilkovic, T John Wu, Albert Beckers, Maya B Lodish, and Constantine A Stratakis

Cushing’s disease (CD) in children is caused by adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas. Germline or somatic mutations in genes such as MEN1, CDKIs, AIP, and USP8 have been identified in pediatric CD, but the genetic defects in a significant percentage of cases are still unknown. In this study, we investigated the orphan G-protein-coupled receptor GPR101, a gene known to be involved in somatotropinomas, for its possible involvement in corticotropinomas. We performed GPR101 sequencing, expression analyses by RT-qPCR and immunostaining, and functional studies (cell proliferation, pituitary hormone secretion, and cAMP measurement) in a series of patients with sporadic CD secondary to ACTH-secreting adenomas in whom we extracted DNA from peripheral blood and pituitary tumor samples (n=36). No increased GPR101 expression was observed in tumors compared with normal pituitary (NP) tissues, nor did we find a correlation between GPR101 and ACTH expression levels. Sequence analysis revealed a very rare germline heterozygous GPR101 variant (p.G31S) in one patient with CD. Overexpression of the p.G31S variant did not lead to increased growth and proliferation, although modest effects on cAMP signaling were observed. GPR101 is not overexpressed in ACTH-secreting tumors compared with NPs. In conclusion, rare germline GPR101 variant was found in one patient with CD, but in vitro studies did not support a consistent pathogenic effect. GPR101 is unlikely to be involved in the pathogenesis of CD.

Free access

Takako Araki, Ning-Ai Liu, Yukiko Tone, Daniel Cuevas-Ramos, Roy Heltsley, Masahide Tone, and Shlomo Melmed

Cushing’s syndrome is caused by excessive adrenocorticotropic hormone (ACTH) secretion derived from pituitary corticotroph tumors (Cushing disease) or from non-pituitary tumors (ectopic Cushing’s syndrome). Hypercortisolemic features of ectopic Cushing’s syndrome are severe, and no definitive treatment for paraneoplastic ACTH excess is available. We aimed to identify subcellular therapeutic targets by elucidating transcriptional regulation of the human ACTH precursor POMC (proopiomelanocortin) and ACTH production in non-pituitary tumor cells and in cell lines derived from patients with ectopic Cushing’s syndrome. We show that ectopic hPOMC transcription proceeds independently of pituitary-specific Tpit/Pitx1 and demonstrate a novel E2F1-mediated transcriptional mechanism regulating hPOMC. We identify an E2F1 cluster binding to the proximal hPOMC promoter region (−42 to +68), with DNA-binding activity determined by the phosphorylation at Ser-337. hPOMC mRNA expression in cancer cells was upregulated (up to 40-fold) by the co-expression of E2F1 and its heterodimer partner DP1. Direct and indirect inhibitors of E2F1 activity suppressed hPOMC gene expression and ACTH by modifying E2F1 DNA-binding activity in ectopic Cushing’s cell lines and primary tumor cells, and also suppressed paraneoplastic ACTH and cortisol levels in xenografted mice. E2F1-mediated hPOMC transcription is a potential target for suppressing ACTH production in ectopic Cushing’s syndrome.

Free access

Paraskevi Xekouki and Constantine A Stratakis

Succinate dehydrogenase (SDH) or mitochondrial complex II is a multimeric enzyme that is bound to the inner membrane of mitochondria and has a dual role as it serves both as a critical step of the tricarboxylic acid or Krebs cycle and as a member of the respiratory chain that transfers electrons directly to the ubiquinone pool. Mutations in SDH subunits have been implicated in the formation of familial paragangliomas (PGLs) and/or pheochromocytomas (PHEOs) and in Carney–Stratakis syndrome. More recently, SDH defects were associated with predisposition to a Cowden disease phenotype, renal, and thyroid cancer. We recently described a kindred with the coexistence of familial PGLs and an aggressive GH-secreting pituitary adenoma, harboring an SDHD mutation. The pituitary tumor showed loss of heterozygosity at the SDHD locus, indicating the possibility that SDHD's loss was causatively linked to the development of the neoplasm. In total, 29 cases of pituitary adenomas presenting in association with PHEOs and/or extra-adrenal PGLs have been reported in the literature since 1952. Although a number of other genetic defects are possible in these cases, we speculate that the association of PHEOs and/or PGLs with pituitary tumors is a new syndromic association and a novel phenotype for SDH defects.

Open access

Laura C Hernández-Ramírez, Ryhem Gam, Nuria Valdés, Maya B Lodish, Nathan Pankratz, Aurelio Balsalobre, Yves Gauthier, Fabio R Faucz, Giampaolo Trivellin, Prashant Chittiboina, John Lane, Denise M Kay, Aggeliki Dimopoulos, Stephan Gaillard, Mario Neou, Jérôme Bertherat, Guillaume Assié, Chiara Villa, James L Mills, Jacques Drouin, and Constantine A Stratakis

The CABLES1 cell cycle regulator participates in the adrenal–pituitary negative feedback, and its expression is reduced in corticotropinomas, pituitary tumors with a largely unexplained genetic basis. We investigated the presence of CABLES1 mutations/copy number variations (CNVs) and their associated clinical, histopathological and molecular features in patients with Cushing’s disease (CD). Samples from 146 pediatric (118 germline DNA only/28 germline and tumor DNA) and 35 adult (tumor DNA) CD patients were screened for CABLES1 mutations. CNVs were assessed in 116 pediatric CD patients (87 germline DNA only/29 germline and tumor DNA). Four potentially pathogenic missense variants in CABLES1 were identified, two in young adults (c.532G > A, p.E178K and c.718C > T, p.L240F) and two in children (c.935G > A, p.G312D and c.1388A > G, and p.D463G) with CD; no CNVs were found. The four variants affected residues within or close to the predicted cyclin-dependent kinase-3 (CDK3)-binding region of the CABLES1 protein and impaired its ability to block cell growth in a mouse corticotropinoma cell line (AtT20/D16v-F2). The four patients had macroadenomas. We provide evidence for a role of CABLES1 as a novel pituitary tumor-predisposing gene. Its function might link two of the main molecular mechanisms altered in corticotropinomas: the cyclin-dependent kinase/cyclin group of cell cycle regulators and the epidermal growth factor receptor signaling pathway. Further studies are needed to assess the prevalence of CABLES1 mutations among patients with other types of pituitary adenomas and to elucidate the pituitary-specific functions of this gene.

Restricted access

F W F Hanna, C F Johnston, J E S Ardill, and K D Buchanan

Abstract

Background: Salmon calcitonin (sCT) injection into rats has been reported to induce pituitary tumours. We have demonstrated the co-existence, in the rat-derived α-TSH cell line, of an sCT-like peptide, as well as a receptor for sCT.

Aim: This was to investigate the possible existence of sCT-like immunoreactivity (sCT-LI) in human neuroendocrine tumours.

Methods: A collection of human neuroendocrine tumours was tested, using a highly specific antibody for sCT. Immunostaining was abolished by preabsorption with sCT at concentrations higher than 1 μg/ml. However, as immunofluorescence was still obvious at the highest concentration (100 pg/ml) of hCT employed, any significant cross-reactivity was excluded.

Results: Of the human pituitary null cell tumours studied, positive staining was obtained in 2 out of 12, suggesting a similarity between the rat and human pituitary glands. None of the other pituitary tumours tested showed sCT-LI (these included 8 corticotroph tumours, 6 prolactinomas and 2 somatotroph tumours).

This work was extended to medullary thyroid carcinomas (MTCs) and a further group of neuroendocrine tumours, looking for the specificity of this sCT-LI among the various APUDomas.

All the tested MTCs (n=14) expressed sCT-LI, while none of the examined phaeochromocytomas (n=23), intestinal carcinoids (n=14), lung carcinoids (n=16), stomach carcinoids (n=2), rectal carcinoids (n=2), gastrinomas (n=4), insulinomas (n=12), oat cell carcinomas (n=7), carotid body tumours (n=9), VIPomas (n=3), or a glucagonoma (n=1) expressed sCT-LI. This indicates that this sCT-LI might be unique to MTC (and possibly the pituitary).

Conclusion: The possible existence of the most potent form of CT may provide an explanation for the vasomotor disturbances in MTC and may be a potential new tumour marker for MTC. Phylogenetically, the presence of a lower form of CT in mammalian tissues would give an insight into the conservation of the CT peptide family in evolution.

Endocrine-Related Cancer (1997) 4 191-195

Free access

Liliya Rostomyan, Adrian F Daly, Patrick Petrossians, Emil Nachev, Anurag R Lila, Anne-Lise Lecoq, Beatriz Lecumberri, Giampaolo Trivellin, Roberto Salvatori, Andreas G Moraitis, Ian Holdaway, Dianne J Kranenburg - van Klaveren, Maria Chiara Zatelli, Nuria Palacios, Cecile Nozieres, Margaret Zacharin, Tapani Ebeling, Marja Ojaniemi, Liudmila Rozhinskaya, Elisa Verrua, Marie-Lise Jaffrain-Rea, Silvia Filipponi, Daria Gusakova, Vyacheslav Pronin, Jerome Bertherat, Zhanna Belaya, Irena Ilovayskaya, Mona Sahnoun-Fathallah, Caroline Sievers, Gunter K Stalla, Emilie Castermans, Jean-Hubert Caberg, Ekaterina Sorkina, Renata Simona Auriemma, Sachin Mittal, Maria Kareva, Philippe A Lysy, Philippe Emy, Ernesto De Menis, Catherine S Choong, Giovanna Mantovani, Vincent Bours, Wouter De Herder, Thierry Brue, Anne Barlier, Sebastian J C M M Neggers, Sabina Zacharieva, Philippe Chanson, Nalini Samir Shah, Constantine A Stratakis, Luciana A Naves, and Albert Beckers

Despite being a classical growth disorder, pituitary gigantism has not been studied previously in a standardized way. We performed a retrospective, multicenter, international study to characterize a large series of pituitary gigantism patients. We included 208 patients (163 males; 78.4%) with growth hormone excess and a current/previous abnormal growth velocity for age or final height >2 s.d. above country normal means. The median onset of rapid growth was 13 years and occurred significantly earlier in females than in males; pituitary adenomas were diagnosed earlier in females than males (15.8 vs 21.5 years respectively). Adenomas were ≥10 mm (i.e., macroadenomas) in 84%, of which extrasellar extension occurred in 77% and invasion in 54%. GH/IGF1 control was achieved in 39% during long-term follow-up. Final height was greater in younger onset patients, with larger tumors and higher GH levels. Later disease control was associated with a greater difference from mid-parental height (r=0.23, P=0.02). AIP mutations occurred in 29%; microduplication at Xq26.3 – X-linked acrogigantism (X-LAG) – occurred in two familial isolated pituitary adenoma kindreds and in ten sporadic patients. Tumor size was not different in X-LAG, AIP mutated and genetically negative patient groups. AIP-mutated and X-LAG patients were significantly younger at onset and diagnosis, but disease control was worse in genetically negative cases. Pituitary gigantism patients are characterized by male predominance and large tumors that are difficult to control. Treatment delay increases final height and symptom burden. AIP mutations and X-LAG explain many cases, but no genetic etiology is seen in >50% of cases.

Restricted access

Y de Keyzer, D Vieau, A Picon, and X Bertagna

Cushing's syndrome refers to the manifestations induced by chronic exposure to glucocorticoid excess and may result from various causes that are all associated with tumors. The most frequent one, that which was first recognized by Harvey Cushing (Cushing 1932) – and therefore called Cushing's disease – is due to adrenocorticotropin (ACTH) hypersecretion by a pituitary corticotrope adenoma; the ectopic ACTH syndrome is another, much rarer (∼5-10%) one, caused by a variety of so-called ACTH-secreting non-pituitary tumors; finally, approximately 30% of Cushing's syndromes are ACTH-non-dependent, caused by primary adrenocortical tumors, most often unilateral and either benign or malignant. The first case of ectopic ACTH syndrome was probably reported by Brown (1928) who described the case of a bearded woman with diabetes. At that time the author had no idea that ACTH existed. The discovery of ACTH, the development of an ACTH bioassay, and the pioneering work of Liddle's group eventually led
Free access

R van der Pas, W W de Herder, L J Hofland, and R A Feelders

Cushing's syndrome (CS) is a severe endocrine disorder characterized by chronic cortisol excess due to an ACTH-secreting pituitary adenoma, ectopic ACTH production, or a cortisol-producing adrenal neoplasia. Regardless of the underlying cause, untreated CS is associated with considerable morbidity and mortality. Surgery is the primary therapy for all causes of CS, but surgical failure and ineligibility of the patient to undergo surgery necessitate alternative treatment modalities. The role of medical therapy in CS has been limited because of lack of efficacy or intolerability. In recent years, however, new targets for medical therapy have been identified, both at the level of the pituitary gland (e.g. somatostatin, dopamine, and epidermal growth factor receptors) and the adrenal gland (ectopically expressed receptors in ACTH-independent macronodular adrenal hyperplasia). In this review, results of preclinical and clinical studies with drugs that exert their action through these molecular targets, as well as already established medical treatment options, will be discussed.

Free access

Samuel M O'Toole, Judit Dénes, Mercedes Robledo, Constantine A Stratakis, and Márta Korbonits

The combination of pituitary adenomas (PA) and phaeochromocytomas (phaeo) or paragangliomas (PGL) is a rare event. Although these endocrine tumours may occur together by coincidence, there is mounting evidence that, in at least some cases, classical phaeo/PGL-predisposing genes may also play a role in pituitary tumorigenesis. A new condition that we termed ‘3Pas’ for the association of PA with phaeo and/or PGL was recently described in patients with succinate dehydrogenase mutations and PAs. It should also be noted that the classical tumour suppressor gene, MEN1 that is the archetype of the PA-predisposing genes, is also rarely associated with phaeos in both mice and humans with MEN1 defects. In this report, we review the data leading to the discovery of 3PAs, other associations linking PAs with phaeos and/or PGLs, and the corresponding clinical and molecular genetics.

Free access

S L Asa, O Casar-Borota, P Chanson, E Delgrange, P Earls, S Ezzat, A Grossman, H Ikeda, N Inoshita, N Karavitaki, M Korbonits, E R Laws Jr, M B Lopes, N Maartens, I E McCutcheon, O Mete, H Nishioka, G Raverot, F Roncaroli, W Saeger, L V Syro, A Vasiljevic, C Villa, A Wierinckx, J Trouillas, and and the attendees of 14th Meeting of the International Pituitary Pathology Club, Annecy, France, November 2016

The classification of neoplasms of adenohypophysial cells is misleading because of the simplistic distinction between adenoma and carcinoma, based solely on metastatic spread and the poor reproducibility and predictive value of the definition of atypical adenomas based on the detection of mitoses or expression of Ki-67 or p53. In addition, the current classification of neoplasms of the anterior pituitary does not accurately reflect the clinical spectrum of behavior. Invasion and regrowth of proliferative lesions and persistence of hormone hypersecretion cause significant morbidity and mortality. We propose a new terminology, pituitary neuroendocrine tumor (PitNET), which is consistent with that used for other neuroendocrine neoplasms and which recognizes the highly variable impact of these tumors on patients.