Differential gene expression profiles of POMC-related enzymes, transcription factors and receptors between non-pituitary and pituitary ACTH-secreting tumors

[Fulminant hypercorticism due to ACTG producing pheochromocytoma]

Endogenous hypercorticism (EH) is a severe symptom complex caused by hypercortisolemia; according to the etiology, ACTH-dependent and ACTH-independent variants are distinguished, which, according to the literature, occur in 70-80% and 20-30% of cases, respectively. A rare cause of ACTH-dependent endogenous hypercorticism is ACTH-ectopic syndrome (ACTH-ES) (about 15-20% of cases). ACTH-ES is a syndrome of adrenocorticotropic hormone (ACTH) hyperproduction by neuroendocrine tumors of extrahypophyseal origin. Various tumors can secrete ACTH: bronchopulmonary carcinoid, small cell lung cancer, less frequently, thymus carcinoid, islet cell tumors and pancreatic carcinoid, medullary thyroid cancer, carcinoid tumors of the intestine, ovaries, as well as pheochromocytoma (PCC).This publication presents a clinical case of rarely detected paraneoplastic ACTH production by pheochromocytoma. The patient had clinical manifestations of hypercorticism, therefore, she applied to the Russian National Research Center of Endocrinology of the Ministry of Health of Russia. During the examination Cushing's syndrome (CS) was confirmed, multispiral computed tomography (MSCT) of the abdominal cavity revealed a voluminous formation of the left adrenal gland. Additional examination recorded a multiple increase in urinary catecholamine levels. Subsequently, the patient underwent left-sided adrenalectomy. The diagnosis of pheochromocytoma was confirmed morphologically, immunohistochemical study demonstrated intensive expression of chromogranin A and ACTH by tumor cells.

Approach to the Patient: Diagnosis of Cushing Syndrome

Cushing syndrome results from supraphysiological exposure to glucocorticoids and is associated with significant morbidity and mortality. The pathogenesis includes administration of corticosteroids (exogenous Cushing syndrome) or autonomous cortisol overproduction, whether or not ACTH-dependent (endogenous Cushing syndrome). An early diagnosis of Cushing syndrome is warranted; however, in clinical practice, it is very challenging partly because of resemblance with other common conditions (ie, pseudo-Cushing syndrome). Initial workup should start with excluding local and systemic corticosteroid use. First-line screening tests including the 1-mg dexamethasone suppression test, 24-hour urinary free cortisol excretion, and late-night salivary cortisol measurement should be performed to screen for endogenous Cushing syndrome. Scalp-hair cortisol/cortisone analysis helps in the assessment of long-term glucocorticoid exposure as well as in detection of transient periods of hypercortisolism as observed in cyclical Cushing syndrome. Interpretation of results can be difficult because of individual patient characteristics and hence requires awareness of test limitations. Once endogenous Cushing syndrome is established, measurement of plasma ACTH concentrations differentiates between ACTH-dependent (80%-85%) or ACTH-independent (15%-20%) causes. Further assessment with different imaging modalities and dynamic biochemical testing including bilateral inferior petrosal sinus sampling helps further pinpoint the cause of Cushing's syndrome. In this issue of "Approach to the patient," the diagnostic workup of Cushing syndrome is discussed with answering the questions when to screen, how to screen, and how to differentiate the different causes. In this respect, the latest developments in biochemical and imaging techniques are discussed as well.

Two Pituitary Neuroendocrine Tumors (PitNETs) with Very High Proliferation and TP53 Mutation - High-Grade PitNET or PitNEC?

We report two pituitary neuroendocrine tumors (PitNETs) with very high Ki67 labeling indices, many mitoses and TP53 mutation (nearly all tumor cell nuclei were positive for p53). One of the tumors had bone and liver metastases. One was a corticotroph cell tumor; the other was a lactotroph tumor. The classification of these tumors is the subject of this discussion. Traditionally, pituitary carcinomas are only diagnosed by demonstration of metastases according to the 2017 WHO classification. In contrast, neuroendocrine neoplasms of the gastrointestinal tract and pancreas are classified as either well differentiated NETs that are graded as G1, G2, and G3 based on proliferation as determined by Ki67 indices of ≤ 3, 3-20 and > 20%, and/or < 2, 2-20, and > 20 mitoses per 10 high-power field respectively, or as neuroendocrine carcinomas (NECs) that are poorly differentiated neoplasms with mitoses > 20/HPF and/or a Ki67 index > 20%. With the reclassificiation of PitNETs, in our opinion, the adequate term for the well-differentiated corticotroph tumor that we report is a PitNET G3, whereas the undifferentiated prolactin tumor should be classified as PitNEC. This report expands the spectrum of pituitary neuroendocrine neoplasms.

An Update on Silent Corticotroph Adenomas: Diagnosis, Mechanisms, Clinical Features, and Management

Simple Summary

The 2017 World Health Organization classification of endocrine tumors defines pituitary adenomas based on their cell lineages. T-PIT can serve as a complimentary tool for further identification of silent corticotroph adenomas (SCAs). Unlike functioning corticotroph adenomas in patients with Cushing’s disease, SCAs present no clinical and biochemical features of Cushing’s syndrome. SCAs have been shown to exhibit a more aggressive course characterized by a higher probability of recurrence and resistance to conventional treatment due to their intrinsic histological features. The aim of our review is to offer an update on the diagnosis, mechanisms, clinical features and management of SCAs. Studies of the molecular mechanisms of SCA pathogenesis will provide new directions for the diagnosis and management of SCAs.

Abstract

With the introduction of 2017 World Health Organization (WHO) classification of endocrine tumors, T-PIT can serve as a complementary tool for identification of silent corticotroph adenomas (SCAs) in some cases if the tumor is not classifiable by pituitary hormone expression in pathological tissue samples. An increase of the proportion of SCAs among the non-functioning pituitary adenomas (NFPAs) has been witnessed under the new rule with the detection of T-PIT-positive ACTH-negative SCAs. Studies of molecular mechanisms related to SCA pathogenesis will provide new directions for the diagnosis and management of SCAs. A precise pathological diagnosis can help clinicians better identify SCAs. Understanding clinical features in the context of the pathophysiology of SCAs is critical for optimal management. It could provide information on appropriate follow-up time and aid in early recognition and treatment of potentially aggressive forms. Management approaches include surgical, radiation, and/or medical therapies.

The silent variants of pituitary tumors: demographic, radiological and molecular characteristics

INTRODUCTION

Tumors of the anterior pituitary gland (PTs) are mostly benign tumors with a low prevalence, which has nevertheless increased with advances in brain radiology techniques. Nearly half of PTs are not associated with a clinical endocrine syndrome. These tumors have been indistinctly named non-functioning pituitary adenomas (NFPAs) or silent pituitary tumors (SPTs) and the mechanisms of silencing are not fully known.

AIM

To study the frequency and characterize the silent variant of PTs in a large local series, and to assess their pituitary adenohypophyseal gene expression.

METHODS

This observational, cross-sectional study was performed in a Pituitary Tumor Center of Excellence and involved 268 PTs. After identifying the different subtypes according to the immunohistochemical (IHC) expression of adenohypophyseal hormones, we studied their gene expression by RT-qPCR.

RESULTS

We found that silent tumors were larger and more invasive, but not more proliferative than their functional counterparts. The RT-qPCR complements the IHC typification of PTs, reducing the proportion of null-cell subtype. Finally, some silent PT subtype variants showed lower specific adenohypophyseal hormone gene expression than their functional counterparts, which may contribute to the absence of endocrine manifestations.

CONCLUSIONS

This paper highlights the importance of identifying the silent variant of the PTs subtypes. As expected, silent tumors were larger and more invasive than their functioning counterparts. However, there was no difference in the proliferation activity between them. Finally, the lower specific gene expression in the silent than in the functioning counterparts of some PTs subtypes gives insights into the silencing mechanisms of PTs.

Digital analysis of hormonal immunostaining in pituitary adenomas classified according to WHO 2017 criteria and correlation with preoperative laboratory findings

OBJECTIVE

The authors sought to evaluate clinical and laboratory data from pituitary adenoma (PA) patients with functioning PA (associated with acromegaly [n = 10] or Cushing disease [n = 10]) or nonfunctioning PA (NFPA; n = 10) that were classified according to 2017 WHO criteria (based on the expression of the transcription factors pituitary-specific positive transcription factor 1 [Pit-1], a transcription factor member of the T-box family [Tpit], and steroidogenic factor 1 [SF-1]) and to assess the immunostaining results for growth hormone (GH) and adrenocorticotropic hormone (ACTH) in the corresponding tumors.

METHODS

Clinical and laboratory data were collected retrospectively. The percentage of tumoral cells positive for Pit-1, Tpit, or SF-1 was assessed and ImageJ software was used to evaluate immunopositivity in PAs with 2 different antibodies against GH (primary antibody 1 [AbGH-1] and primary antibody 2 [AbGH-2]) and 2 different antibodies against ACTH (primary antibody 1 [AbACTH-1] and primary antibody 2 [AbACTH-2]).

RESULTS

Cells with positive Pit-1 staining were more frequently observed in lesions from patients with acromegaly (acromegaly group) than in lesions from patients with Cushing disease (Cushing group; p < 0.001) and those from patients with NFPA (NFPA group; p < 0.001). The percentage of Tpit-positive cells was higher in the Cushing group than in the acromegaly (p < 0.001) and NFPA (p < 0.001) groups. No difference was detected regarding SF-1 frequency among all groups (p = 0.855). In acromegalic individuals, GH immunostaining levels varied depending on the antibody employed, and only one of the antibodies (AbGH-2) yielded higher values in comparison with the values for NFPA patients (p < 0.001). For all of the antibodies employed, no significant correlations were detected between GH tissue expression and the laboratory data (serum GH vs AbGH-1, p = 0.933; serum GH vs AbGH-2, p = 0.853; serum insulin-like growth factor-1 [IGF-1] vs AbGH-1, p = 0.407; serum IGF-1 vs AbGH-2, p = 0.881). In the Cushing group data, both antibodies showed similar ACTH tissue expression, which was higher than that obtained in the NFPA group (p < 0.001). There were no significant associations between ACTH immunohistochemical findings and ACTH serum levels (serum ACTH vs AbACTH-1, p = 0.651; serum ACTH vs AbACTH-2, p = 0.987). However, ACTH immunostaining evaluated with AbACTH-1 showed a significant correlation with 24-hour urinary cortisol (24-hour cortisol vs AbACTH-1, p = 0.047; 24-hour cortisol vs AbACTH-2, p = 0.071).

CONCLUSIONS

Immunostaining for Pit-1 and Tpit accurately identified lesions associated with acromegaly and Cushing disease, respectively. Conversely, SF-1 did not differentiate NFPA from lesions of the other two groups. Regarding hormonal tissue detection, results of the current investigation indicate that different antibodies may lead not only to divergent immunohistochemical results but also to lack of correlation with laboratory findings. Finally, PA classification based on transcription factor expression (Pit-1, Tpit, and SF-1), as proposed by the 2017 WHO classification of pituitary tumors, may avoid the limitations of PA classification based solely on digital immunohistochemical detection of hormones.

New types of localization methods for adrenocorticotropic hormone-dependent Cushing's syndrome

The management of endogenous Cushing's syndrome (CS) typically involves two key steps: (i) confirmation of autonomous hypercortisolism and (ii) localization of the cause to guide treatment. Adrenocorticotropic hormone (ACTH)-dependent CS is most commonly due to a pituitary corticotrope tumor which may be so small as to evade detection on conventional magnetic resonance imaging (MRI). Although biochemical testing (e.g., corticotropin stimulation; dexamethasone suppression) can provide an indication of the likely origin of ACTH excess, bilateral inferior petrosal sinus catheterization offers greater accuracy to distinguish pituitary-driven CS [Cushing's Disease (CD)] from the ectopic ACTH syndrome [EAS, e.g., due to a bronchial or pancreatic neuroendocrine tumor (NET)]. In patients with CD, 40-50% may not have a pituitary adenoma (PA) readily visualized on standard clinical MRI. In these subjects, alternative MR sequences (e.g., dynamic, volumetric, fluid attenuation inversion recovery) and higher magnetic field strength (7T > 3T > 1.5T) may aid tumor localization but carry a risk of identifying coincidental (non-causative) pituitary lesions. Molecular imaging is therefore increasingly being deployed to detect small ACTH-secreting PA, with hybrid imaging [e.g., positron emission tomography (PET) combined with MRI] allowing precise anatomical localization of sites of radiotracer (e.g., ¹¹C-methionine) uptake. Similarly, small ACTH-secreting NETs, missed on initial cross-sectional imaging, may be detected using PET tracers targeting abnormal glucose metabolism (e.g., ¹⁸F-fluorodeoxyglucose), somatostatin receptor (SSTR) expression (e.g., ⁶⁸Ga-DOTATATE), amine precursor (e.g., ¹⁸F-DOPA) or amino acid (e.g., ¹¹C-methionine) uptake. Therefore, modern management of ACTH-dependent CS should ideally be undertaken in specialist centers which have an array of cross-sectional and functional imaging techniques at their disposal.

[Surgical treatment of ACTH-ectopic syndrome]

ACTH-ectopic syndrome is a severe, multiple-symptom disease characterized by secretion of adrenocorticotropic hormone (ACTH) by ectopic tumor, increased release of adrenal cortical hormones and clinical picture of hypercorticism. Diagnosis and treatment of ACTH-ectopic syndrome is still difficult problem despite the achievements of modern medicine. There are several unresolved issues including optimal diagnostic algorithm, indications for various surgical procedures and their optimal dates. This review is devoted to these questions.

Identification of Important Invasion-Related Genes in Non-functional Pituitary Adenomas

Non-functioning pituitary adenomas (NFPAs) are locally invasive with high morbidity. The objective of this study was to diagnose important genes and pathways related to the invasiveness of NFPAs and gain more insights into the underlying molecular mechanisms of NFPAs. The gene expression profiles of GSE51618 were downloaded from the Gene Expression Omnibus database with 4 non-invasive NFPA samples, 3 invasive NFPA samples, and 3 normal pituitary gland samples. Differentially expressed genes (DEGs) are screened between invasive NFPA samples and normal pituitary gland samples, followed by pathway and ontology (GO) enrichment analyses. Subsequently, a protein-protein interaction (PPI) network was constructed and analyzed for these DEGs, and module analysis was performed. In addition, a target gene-miRNA network and target gene-TF (transcription factor) network were analyzed for these DEGs. A total of 879 DEGs were obtained. Among them, 439 genes were upregulated and 440 genes were downregulated. Pathway enrichment analysis indicated that the upregulated genes were significantly enriched in cysteine biosynthesis/homocysteine degradation (trans-sulfuration) and PI3K-Akt signaling pathway, while the downregulated genes were mainly associated with docosahexaenoate biosynthesis III (mammals) and chemokine signaling pathway. GO enrichment analysis indicated that the upregulated genes were significantly enriched in animal organ morphogenesis, extracellular matrix, and hormone activity, while the downregulated genes were mainly associated with leukocyte chemotaxis, dendrites, and RAGE receptor binding. Subsequently, ESR1, SOX2, TTN, GFAP, WIF1, TTR, XIST, SPAG5, PPBP, AR, IL1R2, and HIST1H1C were diagnosed as the top hub genes in the upregulated and downregulated PPI networks and modules. In addition, HS3ST1, GPC4, CCND2, and SCD were diagnosed as the top hub genes in the upregulated and downregulated target gene-miRNA networks, while CISH, ISLR, UBE2E3, and CCNG2 were diagnosed as the top hub genes in the upregulated and downregulated target gene-TF networks. The new important DEGs and pathways diagnosed in this study may serve key roles in the invasiveness of NFPAs and indicate more molecular targets for the treatment of NFPAs.

Analysis of pituitary adenoma expression patterns suggests a potential role for the NeuroD1 transcription factor in neuroendocrine tumor-targeting therapies

NeuroD1’s roles in the pathogenesis of pituitary adenomas and in the biology of the normal adult pituitary gland have been insufficiently researched. Much of the work investigating its expression patterns has yielded contradictory results. Objective: morphological study of NeuroD1 transcription factor expression in different types of pituitary adenomas and in normal adult human pituitary glands. Materials and methods: This study analyzed 48 pituitary adenomas and nine normal pituitary glands. In all cases, immunohistochemical study was performed with antibodies to NeuroD1, 6 hormones of adenohypophysis, Ki-67, and CK7. We used confocal laser scanning microscopy, electron microscopy and electron immunocytochemistry. Results: NeuroD1 expression was detected in all cases of plurihormonal adenomas, mammosomatotropinomas, corticotropinomas, prolactinomas, gonadotropinomas, null-cell pituitary adenomas, and in normal pituitary glands. The average numbers of NeuroD1 expressing cells in normal adenohypophysis specimens were significantly lower than in the adenomas overall (p=0.006). NeuroD1 expression was confirmed by several methods (in prolactinomas, by double stain immunohistochemistry; in mammosomatotropinomas, by double stain immunohistochemistry, confocal laser scanning microscopy, and electron immunocytochemistry; and in somatotropinomas, by electron immunocytochemistry). Conclusion: Immunohistochemistry, confocal microscopy, and double label electron immunocytochemistry confirmed NeuroD1’s key role in the pathogenesis of pituitary tumors, regardless of their hormonal state. Its expression level in pituitary adenomas is significantly higher than in the normal pituitary gland and has no reliable correlation with any studied hormones or Ki-67. These findings suggest that NeuroD1 should be investigated further as a potential molecular target in tumor-targeting therapies.

A case of ectopic ACTH syndrome due to DDAVP-sensitive but V1b receptor-negative bronchial typical carcinoid with lymphatic metastasis and plasma ProGRP elevation

Ectopic ACTH syndrome (EAS) is a potentially fatal endocrine disease that results from a variety of neuroendocrine tumors (NETs), such as small cell lung cancer (SCLC) and bronchial typical carcinoid. Typical carcinoid is usually slow growing, not associated with plasma progastrin releasing peptide (ProGRP) elevation. Here, we report a 47-year-old female smoker with progressive typical carcinoid and plasma ProGRP elevation. Several types of Cushingoid features were found on physical examination. In addition, laboratory examination showed elevated plasma ACTH and serum cortisol levels. These findings indicated ACTH-dependent Cushing's syndrome. Moreover, the serum cortisol level was not suppressed by overnight high-dose dexamethasone treatment, suggesting the presence of an extra-pituitary tumor. Contrast-enhanced brain MRI revealed no pituitary adenoma, which also supported the idea that EAS occurred in the present case. Strikingly, chest computed tomographic (CT) scan showed a single 18-mm peripheral nodule in the right middle lobe of the lung. Tumor marker analysis revealed an elevation in plasma ProGRP. These data suggested a possibility that SCLC secreted ACTH and caused EAS in this patient. Of note, the plasma ACTH level was increased (1.7 fold) in l-desamino-8-D-arginine vasopressin (DDAVP) test, also suggesting the specific clinical feature in this case. After additional imaging examinations, we performed surgical resection with the suspicion of limited SCLC. As a result, pathological examination revealed a vasopressin receptor Ib (V1b) receptor-negative bronchial typical carcinoid with ACTH production and mediastinal lymphatic metastasis. In summary, we present a case of EAS caused by progressive bronchial typical carcinoid with plasma ProGRP elevation. We propose a novel subtype of lung typical carcinoid.

Is it time to consider the expression of specific-pituitary hormone genes when typifying pituitary tumours?

The aim of the present study is to check whether we can replicate, in an independent series, previous results showing that the molecular study of pituitary-specific gene expression complements the inmunohistochemical identification of pituitary neuroendocrine tumours. We selected 112 patients (51 (46.4%) women; mean age 51.4±16 years; 102 macroadenomas (91.9%), 9 microadenomas (8.1%)) with complete clinical, radiological, immunohistochemical and molecular data from our data set of pituitary neuroendocrine tumours. Patients were different from those previously studied. We measured the expression of the pituitary-specific hormone genes and type 1 corticotrophin-releasing hormone and arginine vasopressin 1b receptors, by quantitative real-time polymerase chain reaction using TaqMan probes. Afterwards, we identified the different pituitary neuroendocrine tumour subtypes following the 2017 World Health Organization classification of pituitary tumours, calculating the concordance between their molecular and immuhistochemical identification. The concordance between molecular and immunohistochemical identification of functioning pituitary neuroendocrine tumours with the clinical diagnosis was globally similar to the previous series, where the SYBR Green technique was used instead of TaqMan probes. Our results also corroborated the poor correlation between molecular and immunohistochemical detection of the silent pituitary neuroendocrine tumour variants. This discrepancy was more remarkable in lactotroph, null-cell and plurihormonal pituitary neuroendocrine tumours. In conclusion, this study validates the results previously published by our group, highlighting a complementary role for the molecular study of the pituitary-specific hormone genes in the typification of pituitary neuroendocrine tumours subtypes.

Epigenetics of pituitary tumors: Pathogenetic and therapeutic implications

Genetic mutations involving oncogenes or tumor suppressor genes are relatively uncommon in human sporadic pituitary tumors. Instead, increasing evidence has highlighted frequent epigenetic alterations including DNA methylation, histone modifications, and enhanced miRNA expression. This review covers some of this evidence as it illuminates mechanisms of tumorigenesis and highlights therapeutic opportunities.

The retrotransposon gag domain containing protein Rgag4 is an Ikaros target in the pituitary

Previous studies have established the common and critical involvement of the zinc finger protein Ikaros in lymphoid and pituitary cell development and expansion. Key to the assembly of several transcriptional networks, we have demonstrated up-regulation of Ikaros and its interacting partner the C-terminal Binding Protein (CtBP) in response to hypoxia. This prompted us to explore common transcriptional targets using a chromatin immunoprecipitate (ChIP) screen of DNA from pituitary corticotroph cells. This strategy yielded a finite list of targets common to both transcription factors that included the metalloprotease ADAMTS10. In this report, we focus on validation of a second candidate target, the retrotransposon gag domain containing protein Rgag4. We identified the ability of Ikaros to bind the Rgag4 promoter, influence its transcriptional activity, and induce endogenous gene expression. Robust expression of Rgag4 was noted in the anterior lobe of the pituitary gland which was diminished in Ikaros knockout mice. Down-regulation of Rgag4 resulted in profound reduction of hormone gene expression with diminished ACTH secretion, recapitulating the effect of Ikaros deficiency in knockout mice. The results introduce Rgag4 to the repertoire of effectors serving to couple the chromatin remodeler Ikaros with the hormonal stress response.

Overview of the 2017 WHO Classification of Pituitary Tumors

This review focuses on discussing the main changes on the upcoming fourth edition of the WHO Classification of Tumors of the Pituitary Gland emphasizing histopathological and molecular genetics aspects of pituitary neuroendocrine (i.e., pituitary adenomas) and some of the non-neuroendocrine tumors involving the pituitary gland. Instead of a formal review, we introduced the highlights of the new WHO classification by answering select questions relevant to practising pathologists. The revised classification of pituitary adenomas, in addition to hormone immunohistochemistry, recognizes the role of other immunohistochemical markers including but not limited to pituitary transcription factors. Recognizing this novel approach, the fourth edition of the WHO classification has abandoned the concept of "a hormone-producing pituitary adenoma" and adopted a pituitary adenohypophyseal cell lineage designation of the adenomas with subsequent categorization of histological variants according to hormone content and specific histological and immunohistochemical features. This new classification does not require a routine ultrastructural examination of these tumors. The new definition of the Null cell adenoma requires the demonstration of immunonegativity for pituitary transcription factors and adenohypophyseal hormones Moreover, the term of atypical pituitary adenoma is no longer recommended. In addition to the accurate tumor subtyping, assessment of the tumor proliferative potential by mitotic count and Ki-67 index, and other clinical parameters such as tumor invasion, is strongly recommended in individual cases for consideration of clinically aggressive adenomas. This classification also recognizes some subtypes of pituitary neuroendocrine tumors as "high-risk pituitary adenomas" due to the clinical aggressive behavior; these include the sparsely granulated somatotroph adenoma, the lactotroph adenoma in men, the Crooke's cell adenoma, the silent corticotroph adenoma, and the newly introduced plurihormonal Pit-1-positive adenoma (previously known as silent subtype III pituitary adenoma). An additional novel aspect of the new WHO classification was also the definition of the spectrum of thyroid transcription factor-1 expressing pituitary tumors of the posterior lobe as representing a morphological spectrum of a single nosological entity. These tumors include the pituicytoma, the spindle cell oncocytoma, the granular cell tumor of the neurohypophysis, and the sellar ependymoma.

Transcriptomic changes throughout post-hatch development in Gallus gallus pituitary

The pituitary gland is a neuroendocrine organ that works closely with the hypothalamus to affect multiple processes within the body including the stress response, metabolism, growth and immune function. Relative tissue expression (rEx) is a transcriptome analysis method that compares the genes expressed in a particular tissue to the genes expressed in all other tissues with available data. Using rEx, the aim of this study was to identify genes that are uniquely or more abundantly expressed in the pituitary when compared to all other collected chicken tissues. We applied rEx to define genes enriched in the chicken pituitaries at days 21, 22 and 42 post-hatch. rEx analysis identified 25 genes shared between all time points, 295 genes shared between days 21 and 22 and 407 genes unique to day 42. The 25 genes shared by all time points are involved in morphogenesis and general nervous tissue development. The 295 shared genes between days 21 and 22 are involved in neurogenesis and nervous system development and differentiation. The 407 unique day 42 genes are involved in pituitary development, endocrine system development and other hormonally related gene ontology terms. Overall, rEx analysis indicates a focus on nervous system/tissue development at days 21 and 22. By day 42, in addition to nervous tissue development, there is expression of genes involved in the endocrine system, possibly for maturation and preparation for reproduction. This study defines the transcriptome of the chicken pituitary gland and aids in understanding the expressed genes critical to its function and maturation.

Recommendations of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism for the diagnosis of Cushing's disease in Brazil

Although it is a rare condition, the accurate diagnosis and treatment of Cushing's disease is important due to its higher morbidity and mortality compared to the general population, which is attributed to cardiovascular diseases, diabetes mellitus and infections. Screening for hypercortisolism is recommended for patients who present multiple and progressive clinical signs and symptoms, especially those who are considered to be more specific to Cushing's syndrome, abnormal findings relative to age (e.g., spinal osteoporosis and high blood pressure in young patients), weight gain associated with reduced growth rate in the pediatric population and for those with adrenal incidentalomas. Routine screening is not recommended for other groups of patients, such as those with obesity or diabetes mellitus. Magnetic resonance imaging (MRI) of the pituitary, the corticotropin-releasing hormone (CRH) test and the high-dose dexamethasone suppression test are the main tests for the differential diagnosis of ACTH-dependent Cushing's syndrome. Bilateral and simultaneous petrosal sinus sampling is the gold standard method and is performed when the triad of initial tests is inconclusive, doubtful or conflicting. The aim of this article is to provide information on the early detection and establishment of a proper diagnosis of Cushing's disease, recommending follow-up of these patients at experienced referral centers. Arch Endocrinol Metab. 2016;60(3):267-86.

60 YEARS OF POMC: From the prohormone theory to pro-opiomelanocortin and to proprotein convertases (PCSK1 to PCSK9)

Pro-opiomelanocortin (POMC), is a polyprotein expressed in the pituitary and the brain where it is proteolytically processed into peptide hormones and neuropeptides with distinct biological activities. It is the prototype of multipotent prohormones. The prohormone theory was first suggested in 1967 when Chrétien and Li discovered γ-lipotropin and observed that (i) it was part of β-lipotropin (β-LPH), a larger polypeptide characterized 2 years earlier and (ii) its C-terminus was β-melanocyte-stimulating hormone (β-MSH). This discovery led them to propose that the lipotropins might be related biosynthetically to the biologically active β-MSH in a precursor to end product relationship. The theory was widely confirmed in subsequent years. As we celebrate the 50th anniversary of the sequencing of β-LPH, we reflect over the lessons learned from the sequencing of those proteins; we explain their extension to the larger POMC precursor; we examine how the theory of precursor endoproteolysis they inspired became relevant for vast fields in biology; and how it led, after a long and arduous search, to the novel proteolytic enzymes called proprotein convertases. This family of nine enzymes plays multifaceted functions in growth, development, metabolism, endocrine, and brain functions. Their genetics has provided many insights into health and disease. Their therapeutic targeting is foreseeable in the near future. Thus, what started five decades ago as a theory based on POMC fragments, has opened up novel and productive avenues of biological and medical research, including, for our own current interest, a highly intriguing hypocholesterolemic Gln152His PCSK9 mutation in French-Canadian families.

PET imaging in ectopic Cushing syndrome: a systematic review

Cushing syndrome due to endogenous hypercortisolism may cause significant morbidity and mortality. The source of excess cortisol may be adrenal, pituitary, or ectopic. Ectopic Cushing syndrome is sometimes difficult to localize on conventional imaging like CT and MRI. After performing a multilevel thoracoabdominal imaging with CT, the evidence regarding the use of radiotracers for PET imaging is unclear due to significant molecular and etiological heterogeneity of potential causes of ectopic Cushing's syndrome. In our systematic review of literature, it appears that GalLium-based (Ga68) somatostatin receptor analogs have better sensitivity in diagnosis of bronchial carcinoids causing Cushing syndrome and FDG PET appears superior for small-cell lung cancers and other aggressive tumors. Further large-scale studies are needed to identify the best PET tracer for this condition.

Ectopic ACTH syndrome caused by desmopressin-responsive thymic neuroendocrine tumor

A 32-year-old Chinese woman with rapid weight gain and progressive edema was found to have typical Cushingoid features. Her endocrine data were consistent with a diagnosis of ACTH-dependent Cushing's syndrome. To differentiate ectopic ACTH syndrome (EAS) from Cushing's disease (CD), various dynamic endocrine and imaging tests were performed. Her ACTH response was negative to corticotropin-releasing hormone (CRH) and positive to desmopressin. Magnetic resonance imaging of the pituitary showed no mass lesion. Computed tomography scan of the chest revealed a large mass (21 × 15 mm) in the anterior mediastinum, where positron emission tomography showed accumulation of [(18)F] fluorodeoxyglucose. Selective venous sampling showed marked step-up in ACTH level in the internal thoracic vein but not in the cavernous sinus after CRH stimulation. These data are compatible with the diagnosis of EAS. The resected tumor was pathologically consistent with thymic neuroendocrine tumor (NET) positive for ACTH by immunohistochemistry and abundant V1b receptor gene expression by RT-PCR. Postoperatively, her circulating ACTH/cortisol levels became normalized, and responded to stimulation with CRH but not with desmopressin. Her Cushingoid appearance gradually disappeared, and she was free from recurrence 5 years after surgery. This is a rare case of desmopressin-responsive EAS caused by thymic NET with predominant V1b gene expression, which was successfully localized by imaging modalities combined with selective venous sampling.

Lycopene and beta-carotene induce growth inhibition and proapoptotic effects on ACTH-secreting pituitary adenoma cells

Pituitary adenomas comprise approximately 10-15% of intracranial tumors and result in morbidity associated with altered hormonal patterns, therapy and compression of adjacent sella turcica structures. The use of functional foods containing carotenoids contributes to reduce the risk of chronic diseases such as cancer and vascular disorders. In this study, we evaluated the influence of different concentrations of beta-carotene and lycopene on cell viability, colony formation, cell cycle, apoptosis, hormone secretion, intercellular communication and expression of connexin 43, Skp2 and p27(kip1) in ACTH-secreting pituitary adenoma cells, the AtT20 cells, incubated for 48 and 96 h with these carotenoids. We observed a decrease in cell viability caused by the lycopene and beta-carotene treatments; in these conditions, the clonogenic ability of the cells was also significantly decreased. Cell cycle analysis revealed that beta-carotene induced an increase of the cells in S and G2/M phases; furthermore, lycopene increased the proportion of these cells in G0/G1 while decreasing the S and G2/M phases. Also, carotenoids induced apoptosis after 96 h. Lycopene and beta-carotene decreased the secretion of ACTH in AtT20 cells in a dose-dependent manner. Carotenoids blocked the gap junction intercellular communication. In addition, the treatments increased the expression of phosphorylated connexin43. Finally, we also demonstrate decreased expression of S-phase kinase-associated protein 2 (Skp2) and increased expression of p27(kip1) in carotenoid-treated cells. These results show that lycopene and beta-carotene were able to negatively modulate events related to the malignant phenotype of AtT-20 cells, through a mechanism that could involve changes in the expression of connexin 43, Skp2 and p27(kip1); and suggest that these compounds might provide a novel pharmacological approach to the treatment of Cushing's disease.