We recently described X-linked acrogigantism (X-LAG) in sporadic cases of infantile gigantism and a few familial cases of pituitary gigantism in the context of the disorder known as familial isolated pituitary adenomas. X-LAG cases with early onset gigantism (in infants or toddlers) shared copy number gains (CNG) of the distal long arm of chromosome X (Xq26.3). In all patients described to date with Xq26.3 CNG and acro-gigantism, the only coding gene sequence shared by all chromosomal defects was that of GPR101. GPR101 is a class A, rhodopsin-like orphan guanine nucleotide-binding protein (G protein)-coupled receptor (GPCR) with no known endogenous ligand. We review what is known about GPR101, specifically its expression profile in human and animal models, the evidence supporting causation of X-LAG and possibly other roles, including its function in growth, puberty and appetite regulation, as well as efforts to identify putative ligands.
Giampaolo Trivellin, Fabio R Faucz, Adrian F Daly, Albert Beckers, and Constantine A Stratakis
Y de Keyzer, D Vieau, A Picon, and X Bertagna
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.
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.
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.
Kirsten L Dennison, Nyssa Becker Samanas, Quincy Eckert Harenda, Maureen Peters Hickman, Nicole L Seiler, Lina Ding, and James D Shull
The ACI rat model of 17β-estradiol (E2)-induced mammary cancer is highly relevant for use in establishing the endocrine, genetic, and environmental bases of breast cancer etiology and identifying novel agents and strategies for preventing breast cancer. E2 treatment rapidly induces mammary cancer in female ACI rats and simultaneously induces pituitary lactotroph hyperplasia and adenoma. The pituitary tumors can result in undesired morbidity, which compromises long-term studies focused on mammary cancer etiology and prevention. We have defined the genetic bases of susceptibility to E2-induced mammary cancers and pituitary tumors and have utilized the knowledge gained in these studies to develop a novel inbred rat strain, designated ACWi, that retains the high degree of susceptibility to E2-induced mammary cancer exhibited by ACI rats, but lacks the treatment-related morbidity associated with pituitary lactotroph hyperplasia/adenoma. When treated with E2, female ACWi rats developed palpable mammary cancer at a median latency of 116 days, an incidence of 100% by 161 days and exhibited an average of 15.6 mammary tumors per rat following 196 days of treatment. These parameters did not differ from those observed for contemporaneously treated ACI rats. None of the E2-treated ACWi rats were killed before the intended experimental end point due to any treatment-related morbidity other than mammary cancer burden, whereas 20% of contemporaneously treated ACI rats exhibited treatment-related morbidity that necessitated premature killing. The ACWi rat strain is well suited for use by those in the research community, focusing on breast cancer etiology and prevention.
Anne Wierinckx, Carole Auger, Pauline Devauchelle, Arlette Reynaud, Pascale Chevallier, Michel Jan, Gilles Perrin, Michelle Fèvre-Montange, Catherine Rey, Dominique Figarella-Branger, Gérald Raverot, Marie-Françoise Belin, Joël Lachuer, and Jacqueline Trouillas
Although most pituitary tumors are benign, some are invasive or aggressive. In the absence of specific markers of malignancy, only tumors with metastases are considered malignant. To identify markers of invasion and aggressiveness, we focused on prolactin (PRL) tumors in the human and rat. Using radiology and histological methods, we classified 25 human PRL tumors into three groups (non-invasive, invasive, and aggressive–invasive) and compared them with a model of transplantable rat PRL tumors with benign and malignant lineages. Combining histological(mitoses and labeling for Ki-67, P53, pituitary transforming tumor gene (PTTG), and polysialic acid neural cell adhesion molecule) and transcriptomic (microarrays and q-RTPCR) methods with clinical data (post-surgical outcome with case–control statistical analysis), we found nine genes implicated in invasion (ADAMTS6, CRMP1, and DCAMKL3) proliferation (PTTG, ASK, CCNB1, AURKB, and CENPE), or pituitary differentiation (PITX1) showing differential expression in the three groups of tumors (P = 0.015 to 0.0001). A case–control analysis, comparing patients in remission (9 controls) and patients with persistent or recurrent tumors (14 cases) revealed that eight out of the nine genes were differentially up- or downregulated (P = 0.05 to 0.002), with only PTTG showing no correlation with clinical course (P = 0.258). These combined histological and transcriptomic analyses improve the pathological diagnosis of PRL tumors, indicating a reliable procedure for predicting tumor aggressiveness and recurrence potential. The similar gene profiles found between non-invasive human and benign rat tumors, as well as between aggressive–invasive human and malignant rat tumors provide new insights into malignancy in human pituitary tumors.
Anne-Lise Lecoq, Say Viengchareun, Mirella Hage, Jérôme Bouligand, Jacques Young, Audrey Boutron, Philippe Zizzari, Marc Lombès, Philippe Chanson, and Peter Kamenický
Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene predispose humans to pituitary adenomas through unknown molecular mechanisms. The best-known interacting partner of AIP is the aryl hydrocarbon receptor (AhR), a transcription factor that mediates the effects of xenobiotics implicated in carcinogenesis. As 75% of AIP mutations disrupt the physical and/or functional interaction with AhR, we postulated that the tumorigenic potential of AIP mutations might result from altered AhR signaling. We evaluated the impact of AIP mutations on the AhR signaling pathway, first in fibroblasts from AIP-mutated patients with pituitary adenomas, by comparison with fibroblasts from healthy subjects, then in transfected pituitary GH3 cells. The AIP protein level in mutated fibroblasts was about half of that in cells from healthy subjects, but AhR expression was unaffected. Gene expression analyses showed significant modifications in the expression of the AhR target genes CYP1B1 and AHRR in AIP-mutated fibroblasts, both before and after stimulation with the endogenous AhR ligand kynurenine. Kynurenine increased Cyp1b1 expression to a greater extent in GH3 cells overexpressing wild type compared with cells expressing mutant AIP. Knockdown of endogenous Aip in these cells attenuated Cyp1b1 induction by the AhR ligand. Both mutant AIP expression and knockdown of endogenous Aip affected the kynurenine-dependent GH secretion of GH3 cells. This study of human fibroblasts bearing endogenous heterozygous AIP mutations and transfected pituitary GH3 cells shows that AIP mutations affect the AIP protein level and alter AhR transcriptional activity in a gene- and tissue-dependent manner.
Simona Grozinsky-Glasberg, Kate E Lines, Shani Avniel-Polak, Chas Bountra, and Rajesh V Thakker
Neuroendocrine neoplasms (NENs) occur usually as sporadic tumours; however, rarely, they may arise in the context of a hereditary syndrome, such as multiple endocrine neoplasia type 1 (MEN1), an autosomal dominant disorder characterised by the combined development of pancreatic NENs (pNENs) together with parathyroid and anterior pituitary tumours. The therapeutic decision for sporadic pNENs patients is multi-disciplinary and complex: based on the grade and stage of the tumor, various options (and their combinations) are considered, such as surgical excision (either curative or for debulking aims), biological drugs (somatostatin analogues), targeted therapies (mTOR inhibitors or tyrosine kinases (TK)/receptors inhibitors), peptide receptor radioligand therapy (PRRT), chemotherapy, and liver-directed therapies. However, treatment of MEN1-related NENs’ patients is even more challenging, as these tumours are usually multifocal with co-existing foci of heterogeneous biology and malignant potential, rendering them more resistant to the conventional therapies used in their sporadic counterparts, and therefore associated with a poorer prognosis. Moreover, clinical data using standard therapeutic options in MEN1-related NENs are scarce. Recent preclinical studies have identified potentially new targeted therapeutic options for treating MEN1-associated NENs, such as epigenetic modulators, Wnt pathway-targeting β-catenin antagonists, Ras signalling modulators, Akt/mTOR signalling modulators, novel somatostatin receptors analogues, anti-angiogenic drugs, as well as MEN1 gene replacement therapy. The present review aims to summarize these novel therapeutic opportunities for NENs developing in the context of MEN1 syndrome, with an emphasis on pancreatic NENs, as they are the most frequent ones studied in MEN1-NENs models to date; moreover, due to the recent shifting nomenclature of ‘pituitary adenomas’ to ‘pituitary neuroendocrine neoplasms’, relevant data on MEN1-pituitary tumours, when appropriate, are briefly described.
Petteri Ahtiainen, Victoria Sharp, Susana B Rulli, Adolfo Rivero-Müller, Veronika Mamaeva, Matias Röyttä, and Ilpo Huhtaniemi
The etiology of pituitary adenomas remains largely unknown, with the exception of involvement of estrogens in the formation of prolactinomas. We have examined the molecular pathogenesis of prolactin-producing pituitary adenomas in transgenic female mice expressing the human choriongonadotropin (hCG) β-subunit. The LH/CG bioactivity is elevated in the mice, with consequent highly stimulated ovarian progesterone (P4) production, in the face of normal estrogen secretion. Curiously, despite normal estrogen levels, large prolactinomas developed in these mice, and we provide here several lines of evidence that the elevated P4 levels are involved in the growth of these estrogen-dependent tumors. The antiprogestin mifepristone inhibited tumor growth, and combined postgonadectomy estradiol/P4 treatment was more effective than estrogen alone in inducing tumor growth. Evidence for direct growth-promoting effect of P4 was obtained from cultures of primary mouse pituitary cells and rat somatomammotroph GH3 cells. The mouse tumors and cultured cells revealed stimulation of the cyclin D1/cyclin-dependent kinase 4/retinoblastoma protein/transcription factor E2F1 pathway in the growth response to P4. If extrapolated to humans, and given the importance of endogenous P4 and synthetic progestins in female reproductive functions and their pharmacotherapy, it is relevant to revisit the potential role of these hormones in the origin and growth of prolactinomas.