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Free access

Catherine Goudie, Fady Hannah-Shmouni, Mahmure Kavak, Constantine A Stratakis, and William D Foulkes

As medicine is poised to be transformed by incorporating genetic data in its daily practice, it is essential that clinicians familiarise themselves with the information that is now available from more than 50 years of genetic discoveries that continue unabated and increase by the day. Endocrinology has always stood at the forefront of what is called today ‘precision medicine’: genetic disorders of the pituitary and the adrenal glands were among the first to be molecularly elucidated in the 1980s. The discovery of two endocrine-related genes, GNAS and RET, both identified in the late 1980s, contributed greatly in the understanding of cancer and its progression. The use of RET mutation testing for the management of medullary thyroid cancer was among the first and one of most successful applications of genetics in informing clinical decisions in an individualised manner, in this case by preventing cancer or guiding the choice of tyrosine kinase inhibitors in cancer treatment. New information emerges every day in the genetics or system biology of endocrine disorders. This review goes over most of these discoveries and the known endocrine tumour syndromes. We cover key genetic developments for each disease and provide information that can be used by the clinician in daily practice.

Free access

Kerong Shi, Vaishali I Parekh, Swarnava Roy, Shruti S Desai, and Sunita K Agarwal

The multiple endocrine neoplasia type 1 (MEN1) syndrome is caused by germline mutations in the MEN1 gene encoding menin, with tissue-specific tumors of the parathyroids, anterior pituitary, and enteropancreatic endocrine tissues. Also, 30–40% of sporadic pancreatic endocrine tumors show somatic MEN1 gene inactivation. Although menin is expressed in all cell types of the pancreas, mouse models with loss of menin in either pancreatic α-cells, or β-cells, or total pancreas develop β-cell-specific endocrine tumors (insulinomas). Loss of widely expressed tumor suppressor genes may produce tissue-specific tumors by reactivating one or more embryonic-specific differentiation factors. Therefore, we determined the effect of menin overexpression or knockdown on the expression of β-cell differentiation factors in a mouse β-cell line (MIN6). We show that the β-cell differentiation factor Hlxb9 is posttranscriptionally upregulated upon menin knockdown, and it interacts with menin. Hlxb9 reduces cell proliferation and causes apoptosis in the presence of menin, and it regulates genes that modulate insulin level. Thus, upon menin loss or from other causes, dysregulation of Hlxb9 predicts a possible combined mechanism for β-cell proliferation and insulin production in insulinomas. These observations help to understand how a ubiquitously expressed protein such as menin might control tissue-specific tumorigenesis. Also, our findings identify Hlxb9 as an important factor for β-cell proliferation and insulin regulation.

Free access

Rachel S van Leeuwaarde, Joanne M de Laat, Carolina R C Pieterman, Koen Dreijerink, Menno R Vriens, and Gerlof D Valk

Multiple endocrine neoplasia type 1 is a rare autosomal inherited disorder associated with a high risk for patients to simultaneously develop tumors of the parathyroid glands, duodenopancreatic neuroendocrine tumors and tumors of the anterior pituitary gland. Early identification of MEN1 in patients enables presymptomatic screening of manifestations, which makes timely interventions possible with the intention to prevent morbidity and mortality. Causes of death nowadays have shifted toward local or metastatic progression of malignant neuroendocrine tumors. In early cohorts, complications like peptic ulcers in gastrinoma, renal failure in hyperparathyroidism, hypoglycemia and acute hypercalcemia were the primary causes of early mortality. Improved medical treatments of these complications led to a significantly improved life expectancy. The MEN1 landscape is still evolving, considering the finding of breast cancer as a new MEN1-related manifestation and ongoing publications on follow-up and medical care for patients with MEN1. This review aims at summarizing the most recent insights into the follow-up and medical care for patients with MEN1 and identifying the gaps for future research.

Free access

D M Robertson, H G Burger, and P J Fuller

Inhibin and activin are members of the transforming growth factor beta (TGFbeta) family of cytokines produced by the gonads, with a recognised role in regulating pituitary FSH secretion. Inhibin consists of two homologous subunits, alpha and either betaA or betaB (inhibin A and B). Activins are hetero- or homodimers of the beta-subunits. Inhibin and free alpha subunit are known products of two ovarian tumours (granulosa cell tumours and mucinous carcinomas). This observation has provided the basis for the development of a serum diagnostic test to monitor the occurrence and treatment of these cancers. Transgenic mice with an inhibin alpha subunit gene deletion develop stromal/granulosa cell tumours suggesting that the alpha subunit is a tumour suppressor gene. The role of inhibin and activin is reviewed in ovarian cancer both as a measure of proven clinical utility in diagnosis and management and also as a factor in the pathogenesis of these tumours. In order to place these findings into perspective the biology of inhibin/activin and of other members of the TGFbeta superfamily is also discussed.

Free access

Ji Won Kim, Dharmendra K Yadav, Soo Jin Kim, Moo-Yeol Lee, Jung-Min Park, Bum Seok Kim, Mi-hyun Kim, Hyeung-geun Park, and Keon Wook Kang

GV1001, a 16-amino acid fragment of the human telomerase reverse transcriptase catalytic subunit (hTERT), has been developed as an injectable formulation of cancer vaccine. Here, we revealed for the first time that GV1001 is a novel ligand for gonadotropin-releasing hormone receptor (GnRHR). The docking prediction for GV1001 against GnRHR showed high binding affinity. Binding of GV1001 to GnRHR stimulated the Gαs-coupled cAMP signaling pathway and antagonized Gαq-coupled Ca2+ release by leuprolide acetate (LA), a GnRHR agonist. Repeated injection of GV1001 attenuated both serum testosterone level and seminal vesicle weight via desensitization of hypothalamic–pituitary–gonadal (HPG) axis. We then tested whether GV1001 has an inhibitory effect on tumor growth of LNCaP cells, androgen receptor–positive human prostate cancer (PCa) cells. GV1001 significantly inhibited tumor growth and induced apoptosis in LNCaP-implanted xenografts. Interestingly, mRNA expressions of matrix metalloproteinase 2 and matrix metalloproteinase 9 were suppressed by GV1001, but not by LA. Moreover, GV1001 significantly inhibited the proliferation and migration of PCa cells and induced apoptosis in a concentration-dependent manner. Our findings suggest that GV1001 functions as a biased GnRHR ligand to selectively stimulate the Gαs/cAMP pathway, with anti-proliferative and anti-migratory effects on human PCa.

Free access

Daniel S Olsson, Casper Hammarstrand, Ing-Liss Bryngelsson, Anna G Nilsson, Eva Andersson, Gudmundur Johannsson, and Oskar Ragnarsson

Whether patients with non-functioning pituitary adenoma (NFPA) are at increased risk of developing malignant tumours has been sparsely studied and is a matter of debate. In this study, we have investigated the incidence of malignant tumours in a large and unselected group of patients with NFPA. The study was nationwide and included all patients diagnosed with NFPA between 1987 and 2011 (n = 2795) in Sweden, identified in the National Patient Register. Malignant tumours, occurring after the NFPA diagnosis, were identified in the Swedish Cancer Register between 1987 and 2014. Standardised incidence ratios (SIRs) for malignant tumours with 95% confidence intervals (CI) were calculated using the Swedish population as reference. In total, 448 malignant tumours were detected in 386 patients with NFPA, as compared to 368 expected malignancies in the general population (SIR 1.22 (95% CI 1.11–1.33)). The incidence of neoplasms of the brain was increased (SIR 5.83 (95% CI 4.03–8.14)). When analysing the total incidence of malignancies excluding neoplasms of the brain, the overall SIR was still increased (SIR 1.14 (95% CI 1.03–1.26)). The incidence of malignant neoplasm of skin other than malignant melanoma (SIR 1.99 (95% CI 1.55–2.52)) and malignant melanoma (SIR 1.62 (95% CI 1.04–2.38)) were increased, whereas the incidence of breast cancer (SIR 0.65 (95% CI 0.42–0.97)) was decreased. The incidence of other types of malignancies did not differ significantly from the expected incidence in the general population. In conclusion, patients with NFPA have an increased overall risk of developing malignancies. To what extent these findings are due to more frequent medical surveillance, genetic predisposition or endocrine changes, remains unknown.

Free access

Shoucheng Ning, Susan J Knox, Griffith R Harsh, Michael D Culler, and Laurence Katznelson

Somatostatin analogs are a mainstay of medical therapy in patients with GH producing human pituitary tumors, and it has been suggested that somatostatin analogs may be radioprotective. We utilized GH secreting rat GH3 cells to investigate whether a somatostatin analog may limit the effects of radiation on proliferation and apoptosis in vitro and on tumor growth in vivo. Treatment with lanreotide alone at doses of either 100 or 1000 nM for 48 h reduced clonogenic survival by 5–10%. Radiation alone produced a dose-dependent survival curve with a SF2 of 48–55%, and lanreotide had no effect on this curve. The addition of lanreotide resulted in a 23% increase in the proportion of apoptotic sub-G1 cells following irradiation (P<0.01). In a mouse GH3 tumor xenograft model, lanreotide 10 mg/kg moderately inhibited the growth of GH3 tumors, with a 4× tumor growth delay (TGD) time that ranged from 4.5 to 8.3 days. Fractionated local tumor radiation alone significantly inhibited tumor growth and produced a TGD of 35.1±5.7 days for 250 cGy fractions. The combination of lanreotide, either antecedent to or concurrent, with radiation of 250, 200 or 150 cGy/fraction for 5 days inhibited tumor growth and produced the TGD times that were similar to radiation alone (P>0.05). Pretreatment with lanreotide had the most significant radiosensitizing effect. These studies demonstrate that the somatostatin analog lanreotide is not radioprotective in GH3 cells, and further studies are necessary to determine the impact of lanreotide on apoptosis.

Free access

Pedro Marques, Sayka Barry, Eivind Carlsen, David Collier, Amy Ronaldson, Sherine Awad, Neil Dorward, Joan Grieve, Nigel Mendoza, Samiul Muquit, Ashley B Grossman, Frances Balkwill, and Márta Korbonits

Tumour-associated fibroblasts (TAFs) are key elements of the tumour microenvironment, but their role in pituitary neuroendocrine tumours (PitNETs) has been little explored. We hypothesised that TAF-derived cytokines may play a role in tumour aggressiveness and that their release can be inhibited by somatostatin analogues. TAFs were isolated and cultured from 16 PitNETs (11 clinically non-functioning tumours and 5 somatotropinomas). The fibroblast secretome was assessed with a 42-plex cytokine array before and after multiligand somatostatin receptor agonist pasireotide treatment. Angiogenesis and epithelial-to-mesenchymal transition pathway assessment included CD31, E-cadherin and ZEB1 expression. GH3 cells treated with TAF- or skin fibroblast-conditioned medium were assessed for migration, invasion and cell morphology changes. PitNET TAFs secreted significant amounts of cytokines including CCL2, CCL11, VEGF-A, CCL22, IL-6, FGF-2 and IL-8. TAFs from PitNETs with cavernous sinus invasion secreted higher IL-6 levels compared to fibroblasts from non-invasive tumours (P = 0.027). Higher CCL2 release from TAFs correlated with more capillaries (r = 0.672, P = 0.004), and TAFs from PitNETs with a higher Ki-67 tended to secrete more CCL2 (P = 0.058). SST1 is the predominant somatostatin receptor in TAFs, and pasireotide decreased TAF-derived IL-6 by 80% (P < 0.001) and CCL2 by 35% (P = 0.038). GH3 cells treated with TAF-conditioned medium showed increased migration and invasion compared to cells treated with skin fibroblast-conditioned medium, with morphological and E-cadherin and ZEB1 expression changes suggesting epithelial-to-mesenchymal transition. TAF-derived cytokines may increase PitNET aggressiveness, alter angiogenesis and induce epithelial-to-mesenchymal transition changes. Pasireotide’s inhibitory effect on TAF-derived cytokines suggest that this effect may play a role in its anti-tumour effects.

Open access

W Imruetaicharoenchoke, A Fletcher, W Lu, R J Watkins, B Modasia, V L Poole, H R Nieto, R J Thompson, K Boelaert, M L Read, V E Smith, and C J McCabe

Pituitary tumor-transforming gene 1-binding factor (PTTG1IP; PBF) is a multifunctional glycoprotein, which is overexpressed in a wide range of tumours, and significantly associated with poorer oncological outcomes, such as early tumour recurrence, distant metastasis, extramural vascular invasion and decreased disease-specific survival. PBF transforms NIH 3T3 fibroblasts and induces tumours in nude mice, while mice harbouring transgenic thyroidal PBF expression show hyperplasia and macrofollicular lesions. Our assumption that PBF becomes an oncogene purely through increased expression has been challenged by the recent report of mutations in PBF within the Catalogue of Somatic Mutations in Cancer (COSMIC) database. We therefore sought to determine whether the first 10 PBF missense substitutions in human cancer might be oncogenic. Anisomycin half-life studies revealed that most mutations were associated with reduced protein stability compared to wild-type (WT) PBF. Proliferation assays narrowed our interest to two mutational events which significantly altered cell turnover: C51R and R140W. C51R was mainly confined to the endoplasmic reticulum while R140W was apparent in the Golgi apparatus. Both C51R and R140W lost the capacity to induce cellular migration and significantly reduced cell invasion. Colony formation and soft agar assays demonstrated that, in contrast to WT PBF, both mutants were unable to elicit significant colony formation or anchorage-independent growth. However, C51R and R140W retained the ability to repress radioiodide uptake, a functional hallmark of PBF. Our data reveal new insight into PBF function and confirm that, rather than being oncogenic, mutations in PBF are likely to be passenger effects, with overexpression of PBF the more important aetiological event in human cancer.

Free access

Tullio Florio, Federica Barbieri, Renato Spaziante, Gianluigi Zona, Leo J Hofland, Peter M van Koetsveld, Richard A Feelders, Günter K Stalla, Marily Theodoropoulou, Michael D Culler, Jesse Dong, John E Taylor, Jacques-Pierre Moreau, Alexandru Saveanu, Ginette Gunz, Henry Dufour, and Philippe Jaquet

Dopamine D2 and somatostatin receptors (sstrs) were reported to affect non-functioning pituitary adenoma (NFPA) proliferation in vitro. However, the reported results differ according to the experimental conditions used. We established an experimental protocol allowing reproducible evaluation of NFPA cell proliferation in vitro, to test and compare the antiproliferative effects of dopamine and somatostatin analogs (alone or in combination) with the activity of the dopamine–somatostatin chimeric molecule BIM-23A760. The protocol was utilized by four independent laboratories, studying 38 fibroblast-deprived NFPA cell cultures. Cells were characterized for GH, POMC, sstr1–sstr5, total dopamine D2 receptor (D2R) (in all cases), and D2 receptor long and short isoforms (in 15 out of 38 cases) mRNA expression and for α-subunit, LH, and FSH release. D2R, sstr3, and sstr2 mRNAs were consistently observed, with the dominant expression of D2R (2.9±2.6 copy/copy β-glucuronidase; mean±s.e.m.), when compared with sstr3 and sstr2 (0.6±1.0 and 0.3±0.6 respectively). BIM-23A760, a molecule with high affinity for D2R and sstr2, significantly inhibited [3H]thymidine incorporation in 23 out of 38 (60%) NFPA cultures (EC50=1.2 pM and E max=−33.6±3.7%). BIM-23A760 effects were similar to those induced by the selective D2R agonist cabergoline that showed a statistically significant inhibition in 18 out of 27 tumors (compared with a significant inhibition obtained in 17 out of 27 tumors using BIM-23A760, in the same subgroup of adenomas analyzed), while octreotide was effective in 13 out of 27 cases. In conclusion, superimposable data generated in four independent laboratories using a standardized protocol demonstrate that, in vitro, chimeric dopamine/sstr agonists are effective in inhibiting cell proliferation in two-thirds of NFPAs.