Isolated familial somatotropinoma: 11q13-loh and gene/protein expression analysis suggests a possible involvement of aip also in non-pituitary tumorigenesis

Germline AIP variants in sporadic young acromegaly and pituitary gigantism: clinical and genetic insights from a Han Chinese cohort

PURPOSE

Variants in the Aryl hydrocarbon receptor-interacting protein (AIP) gene have been identified in sporadic acromegaly and pituitary gigantism, especially in young patients, with a predisposition to aggressive clinical phenotype and poor treatment efficacy. The clinical characteristics of patients with sporadic acromegaly and pituitary gigantism as well as AIP variants in Han Chinese have been rarely reported. We aimed to identify AIP gene variants and analyze the clinical characteristics of patients with sporadic acromegaly and pituitary gigantism in Han Chinese.

METHODS

The study included 181 sporadic acromegaly (N = 163) and pituitary gigantism (N = 18) patients with an onset age of no more than 45 years old, who were diagnosed, treated, and followed up in Huashan Hospital. All 6 exons and their flanking regions of the AIP gene were analyzed with Sanger sequencing or NGS. The clinical characteristics were compared between groups with and without AIP variants.

RESULTS

Germline AIP variants were found in 15/181 (8.29%) cases. In patients with an onset age ≤30 years old, AIP variants were identified in 12/133 (9.02%). Overall, 13 variants were detected. The pathogenic (P) variants p.R304X and p.R81X were identified in four cases, with two instances of each variant. Six exon variants (p.C254R, p.K103fs, p.Q228fs, p.Y38X, p.Q213*, and p.1115 fs) have not been reported before, which were likely pathogenic (LP). Patients with P/LP variants had younger onset ages, a higher prevalence of pituitary gigantism, larger tumor volumes, and a higher percentage of Ki-67-positive cells in tumors. In addition, the group with P/LP variants showed a less significant reduction of GH levels in an acute octreotide suppression test (OST) [17.7% (0, 65.0%) vs. 80.5% (63.9%, 90.2%), P = 0.001], and a trend of less GH decrease after the 3-month treatment with long-acting somatostatin analogs (SSAs).

CONCLUSION

Germline AIP variants existed in sporadic Chinese Han acromegaly and pituitary gigantism patients and were more likely to be detected in young patients. AIP variants were associated with more aggressive tumor phenotypes and less response to SSA treatment.

Large Scale Molecular Studies of Pituitary Neuroendocrine Tumors: Novel Markers, Mechanisms and Translational Perspectives

Simple Summary

Pituitary neuroendocrine tumors are non-cancerous tumors of the pituitary gland, that may overproduce hormones leading to serious health conditions or due to tumor size cause chronic headache, vertigo or visual impairment. In recent years pituitary neuroendocrine tumors are studied with the latest molecular biology methods that simultaneously investigate a large number of factors to understand the mechanisms of how these tumors develop and how they could be diagnosed or treated. In this review article, we have studied literature reports, compiled information and described molecular factors that could affect the development and clinical characteristics of pituitary neuroendocrine tumors, discovered factors that overlap between several studies using large scale molecular analysis and interpreted the potential involvement of these factors in pituitary tumor development. Overall, this study provides a valuable resource for understanding the biology of pituitary neuroendocrine tumors.

Abstract

Pituitary neuroendocrine tumors (PitNETs) are non-metastatic neoplasms of the pituitary, which overproduce hormones leading to systemic disorders, or tumor mass effects causing headaches, vertigo or visual impairment. Recently, PitNETs have been investigated in large scale (exome and genome) molecular analyses (transcriptome microarrays and sequencing), to uncover novel markers. We performed a literature analysis on these studies to summarize the research data and extrapolate overlapping gene candidates, biomarkers, and molecular mechanisms. We observed a tendency in samples with driver mutations (GNAS, USP8) to have a smaller overall mutational rate, suggesting driver-promoted tumorigenesis, potentially changing transcriptome profiles in tumors. However, direct links from drivers to signaling pathways altered in PitNETs (Notch, Wnt, TGF-β, and cell cycle regulators) require further investigation. Modern technologies have also identified circulating nucleic acids, and pinpointed these as novel PitNET markers, i.e., miR-143-3p, miR-16-5p, miR-145-5p, and let-7g-5p, therefore these molecules must be investigated in the future translational studies. Overall, large-scale molecular studies have provided key insight into the molecular mechanisms behind PitNET pathogenesis, highlighting previously reported molecular markers, bringing new candidates into the research field, and reapplying traditional perspectives to newly discovered molecular mechanisms.

PDE4 subtypes in cancer

Cyclic nucleotide phosphodiesterases (PDE) break down cyclic nucleotides such as cAMP and cGMP, reducing the signaling of these important intracellular second messengers. Several unique families of phosphodiesterases exist, and certain families are clinically important modulators of vasodilation. In the current work, we have summarized the body of literature that describes an emerging role for the PDE4 subfamily of phosphodiesterases in malignancy. We have systematically investigated PDE4A, PDE4B, PDE4C, and PDE4D isoforms and found evidence associating them with several cancer types including hematologic malignancies and lung cancers, among others. In this review, we compare the evidence examining the functional role of each PDE4 subtype across malignancies, looking for common signaling themes, signaling pathways, and establishing the case for PDE4 subtypes as a potential therapeutic target for cancer treatment.

From dwarves to giants: South American's contribution to the history of growth hormone and related disorders

The aim of this article is to present a historical review on giants and dwarves living in South America and the contribution of South America's researchers to scientific advances on growth hormone (GH) and human disorders related to GH excess and GH deficiency (GHD). We went back in time to investigate facts and myths stemming from countless reports of giants who lived in the Patagonia region, focusing on what is currently known about gigantism in South America. Additionally, we have reviewed the exceptional work carried out in two of the world's largest cohorts of dwarfism related to GH-IGF axis: one living in Itabaianinha, Brazil, suffering from severe GHD due to a mutation in the GHRH receptor (GHRHR) gene, and the other living in El Oro and Loja provinces of Ecuador, who are carriers of GH receptor gene mutation that causes total GH insensitivity (Laron syndrome). Importantly, we present an overview of the outstanding medical contribution of Jose Dantas de Souza Leite, a Brazilian physician that described the first cases of acromegaly, and Bernardo Alberto Houssay, an Argentine researcher graced with the Nobel Prize, who was one the first scientists to establish a link between GH and glucose metabolism.

Genetics of Pituitary Tumours

Pituitary tumours are relatively common in the general population. Most often they occur sporadically, with somatic mutations accounting for a significant minority of somatotroph and corticotroph adenomas. Pituitary tumours can also develop secondary to germline mutations as part of a complex syndrome or as familial isolated pituitary adenomas. Tumours occurring in a familial setting may present at a younger age and can behave more aggressively with resistance to treatment. This chapter will focus on the genetics and molecular pathogenesis of pituitary tumours.

Surgery, Octreotide, Temozolomide, Bevacizumab, Radiotherapy, and Pegvisomant Treatment of an AIP Mutation‒Positive Child

CONTEXT

Inactivating germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene are linked to pituitary adenoma predisposition. Here, we present the youngest known patient with AIP-related pituitary adenoma.

CASE DESCRIPTION

The patient presented at the age of 4 years with pituitary apoplexy and left ptosis with severe visual loss following a 1-year history of abdominal pain, headaches, and rapid growth. His IGF-1 level was 5× the upper limit of normal, and his random GH level was 1200 ng/mL. MRI showed a 43 × 24 × 35‒mm adenoma with suprasellar extension invading the left cavernous sinus (Knosp grade 4). After transsphenoidal surgery, histology showed a grade 2A sparsely granulated somatotropinoma with negative O6-methylguanine-DNA methyltransferase and positive vascular endothelial growth factor staining. Genetic testing identified a heterozygous germline nonsense AIP mutation (p.Arg81Ter). Exome sequencing of the tumor revealed that it had lost the entire maternal chromosome-11, rendering it hemizygous for chromosome-11 and therefore lacking functional copies of AIP in the tumor. He was started on octreotide, but because the tumor rapidly regrew and IGF-1 levels were unchanged, temozolomide was initiated, and intensity-modulated radiotherapy was administered 5 months after surgery. Two months later, bevacizumab was added, resulting in excellent tumor response. Although these treatments stabilized tumor growth over 4 years, IGF-1 was normalized only after pegvisomant treatment, although access to this medication was intermittent. At 3.5 years of follow-up, gamma knife treatment was administered, and pegvisomant dose increase was indicated.

CONCLUSION

Multimodal treatment with surgery, long-acting octreotide, radiotherapy, temozolomide, bevacizumab, and pegvisomant can control genetically driven, aggressive, childhood-onset somatotropinomas.

Emergence of Pituitary Adenoma in a Child during Surveillance: Clinical Challenges and the Family Members' View in an AIP Mutation-Positive Family

INTRODUCTION

Germline aryl hydrocarbon receptor-interacting protein (AIP) mutations are responsible for 15-30% of familial isolated pituitary adenomas (FIPAs). We report a FIPA kindred with a heterozygous deletion in AIP, aiming to highlight the indications and benefits of genetic screening, variability in clinical presentations, and management challenges in this setting.

PATIENTS

An 18-year-old male was diagnosed with a clinically nonfunctioning pituitary adenoma (NFPA). Two years later, his brother was diagnosed with a somatolactotrophinoma, and a small Rathke's cleft cyst and a microadenoma were detected on screening in their 17-year-old sister. Following amenorrhoea, their maternal cousin was diagnosed with hyperprolactinaemia and two distinct pituitary microadenomas. A 12-year-old niece developed headache and her MRI showed a microadenoma, not seen on a pituitary MRI scan 3 years earlier.

DISCUSSION

Out of the 14 members harbouring germline AIP mutations in this kindred, 5 have pituitary adenoma. Affected members had different features and courses of disease. Bulky pituitary and not fully suppressed GH on OGTT can be challenging in the evaluation of females in teenage years. Multiple pituitary adenomas with different secretory profiles may arise in the pituitary of these patients. Small, stable NFPAs can be present in mutation carriers, similar to incidentalomas in the general population. Genetic screening and baseline review, with follow-up of younger subjects, are recommended in AIP mutation-positive families.

Genetic Aspects of Pituitary Adenomas

Although most of pituitary adenomas are benign, they may cause significant burden to patients. Sporadic adenomas represent the vast majority of the cases, where recognized somatic mutations (eg, GNAS or USP8), as well as altered gene-expression profile often affecting cell cycle proteins have been identified. More rarely, germline mutations predisposing to pituitary adenomas -as part of a syndrome (eg, MEN1 or Carney complex), or isolated to the pituitary (AIP or GPR101) can be identified. These alterations influence the biological behavior, clinical presentations and therapeutic responses, and their full understanding helps to provide appropriate care for these patients.

SNPs in the aryl hydrocarbon receptor-interacting protein gene associated with sporadic non-functioning pituitary adenoma

Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene have previously been associated with a predisposition to pituitary adenomas. However, to the best of our knowledge, mutations in AIP that relate specifically to sporadic non-functioning pituitary adenomas (NFPAs) have yet to be reported. Therefore, the present study aimed to identify single nucleotide polymorphisms (SNPs) in the AIP gene that may be associated with NFPAs. Peripheral blood samples and the entire coding sequence of the AIP gene from 56 patients with NFPAs and 56 controls were analyzed in triplicate. Of the 56 patients with NFPAs, 9 patients (16.1%) were identified as harboring five different SNPs, although no germline mutations in the AIP gene were detected in any of the patients. Three different SNPs (7051C>T, 8012G>C and 8020G>C) were identified in exons 4 and 6 in 3 different patients (each in 1 patient). Two different SNPs (7318C>A and 7886A>G) were identified in exons 5 and 6, respectively, in 6 different patients (each in 3 patients). No SNPs or germline mutations in the AIP gene were identified in the controls. The results of the present study suggested that mutations in the AIP gene might not have an important role in the tumorigenesis of NFPAs. However, further studies are required in order to investigate potential molecular and genetic mechanisms that may underlie the involvement of AIP in NFPA.

MEN1, MEN4, and Carney Complex: Pathology and Molecular Genetics

Pituitary adenomas are a common feature of a subset of endocrine neoplasia syndromes, which have otherwise highly variable disease manifestations. We provide here a review of the clinical features and human molecular genetics of multiple endocrine neoplasia (MEN) type 1 and 4 (MEN1 and MEN4, respectively) and Carney complex (CNC). MEN1, MEN4, and CNC are hereditary autosomal dominant syndromes that can present with pituitary adenomas. MEN1 is caused by inactivating mutations in the MEN1 gene, whose product menin is involved in multiple intracellular pathways contributing to transcriptional control and cell proliferation. MEN1 clinical features include primary hyperparathyroidism, pancreatic neuroendocrine tumours and prolactinomas as well as other pituitary adenomas. A subset of patients with pituitary adenomas and other MEN1 features have mutations in the CDKN1B gene; their disease has been called MEN4. Inactivating mutations in the type 1α regulatory subunit of protein kinase A (PKA; the PRKAR1A gene), that lead to dysregulation and activation of the PKA pathway, are the main genetic cause of CNC, which is clinically characterised by primary pigmented nodular adrenocortical disease, spotty skin pigmentation (lentigines), cardiac and other myxomas and acromegaly due to somatotropinomas or somatotrope hyperplasia.

A clinically novel AIP mutation in a patient with a very large, apparently sporadic somatotrope adenoma

Heterozygous germline inactivating mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene lead to pituitary adenomas that most frequently present in the setting of familial isolated pituitary adenoma syndrome, usually as somatotropinomas and prolactinomas. More recently, they have been found in a significant percentage of young patients presenting with pituitary macroadenoma without any apparent family history. We describe the case of a 19-year-old man who presented with a gigantic somatotropinoma. His family history was negative. His peripheral DNA showed a heterozygous AIP mutation (p.I13N), while tumor tissue only had the mutated allele, showing loss of heterozygosity (LOH) and suggesting that the mutation caused the disease.

Genetics and epigenetics of adrenocortical tumors

Adrenocortical tumors are common neoplasms. Most are benign, nonfunctional and clinically irrelevant. However, adrenocortical carcinoma is a rare disease with a dismal prognosis and no effective treatment apart from surgical resection. The molecular genetics of adrenocortical tumors remain poorly understood. For decades, molecular studies relied on a small number of samples and were directed to candidate-genes. This approach, based on the elucidation of the genetics of rare genetic syndromes in which adrenocortical tumors are a manifestation, has led to the discovery of major dysfunctional molecular pathways in adrenocortical tumors, such as the IGF pathway, the Wnt pathway and TP53. However, with the advent of high-throughput methodologies and the organization of international consortiums to obtain a larger number of samples and high-quality clinical data, this paradigm is rapidly changing. In the last decade, genome-wide expression profile studies, microRNA profiling and methylation profiling allowed the identification of subgroups of tumors with distinct genetic markers, molecular pathways activation patterns and clinical behavior. As a consequence, molecular classification of tumors has proven to be superior to traditional histological and clinical methods in prognosis prediction. In addition, this knowledge has also allowed the proposal of molecular-targeted approaches to provide better treatment options for advanced disease. This review aims to summarize the most relevant data on the rapidly evolving field of genetics of adrenal disorders.

A differential diagnosis of inherited endocrine tumors and their tumor counterparts

Inherited endocrine tumors have been increasingly recognized in clinical practice, although some difficulties still exist in differentiating these conditions from their sporadic endocrine tumor counterparts. Here, we list the 12 main topics that could add helpful information and clues for performing an early differential diagnosis to distinguish between these conditions. The early diagnosis of patients with inherited endocrine tumors may be performed either clinically or by mutation analysis in at-risk individuals. Early detection usually has a large impact in tumor management, allowing preventive clinical or surgical therapy in most cases. Advice for the clinical and surgical management of inherited endocrine tumors is also discussed. In addition, recent clinical and genetic advances for 17 different forms of inherited endocrine tumors are briefly reviewed.

Should aip gene screening be recommended in family members of FIPA patients with R16H variant?

Germline mutations of aryl-hydrocarbon-receptor interacting protein (AIP) are associated with pituitary adenoma predisposition. They occur in 20 % of familial isolated pituitary adenoma (FIPA) and in about 3-5 % of sporadic pituitary adenomas, especially in early onset somatotropinomas and prolactinomas. Our aim was to evaluate the clinical and genetic features of a large Italian FIPA family, where an AIP variant was identified. AIP direct sequencing from genomic DNA was carried out in 16 available family members. AIP R16H carriers also underwent magnetic resonance imaging and hormonal assessments. AIP mutations were also searched in 16 patients with sporadic growth hormone-secreting pituitary adenoma and in 6 unrelated patients in whom pituitary adenoma was excluded. We found an AIP R16H variation in two family members harbouring a pituitary adenoma and in 6 unaffected family members. No AIP mutation was found neither in growth hormone-secreting pituitary adenoma patients, nor in the unrelated patients without pituitary adenoma. We report a FIPA family harbouring an AIP R16H change, supporting the hypothesis that the latter represents a variant of unknown significance.

Familial isolated pituitary adenomas (FIPA) and the pituitary adenoma predisposition due to mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene

Pituitary adenomas are one of the most frequent intracranial tumors and occur with a prevalence of approximately 1:1000 in the developed world. Pituitary adenomas have a serious disease burden, and their management involves neurosurgery, biological therapies, and radiotherapy. Early diagnosis of pituitary tumors while they are smaller may help increase cure rates. Few genetic predictors of pituitary adenoma development exist. Recent years have seen two separate, complimentary advances in inherited pituitary tumor research. The clinical condition of familial isolated pituitary adenomas (FIPA) has been described, which encompasses the familial occurrence of isolated pituitary adenomas outside of the setting of syndromic conditions like multiple endocrine neoplasia type 1 and Carney complex. FIPA families comprise approximately 2% of pituitary adenomas and represent a clinical entity with homogeneous or heterogeneous pituitary adenoma types occurring within the same kindred. The aryl hydrocarbon receptor interacting protein (AIP) gene has been identified as causing a pituitary adenoma predisposition of variable penetrance that accounts for 20% of FIPA families. Germline AIP mutations have been shown to associate with the occurrence of large pituitary adenomas that occur at a young age, predominantly in children/adolescents and young adults. AIP mutations are usually associated with somatotropinomas, but prolactinomas, nonfunctioning pituitary adenomas, Cushing disease, and other infrequent clinical adenoma types can also occur. Gigantism is a particular feature of AIP mutations and occurs in more than one third of affected somatotropinoma patients. Study of pituitary adenoma patients with AIP mutations has demonstrated that these cases raise clinical challenges to successful treatment. Extensive research on the biology of AIP and new advances in mouse Aip knockout models demonstrate multiple pathways by which AIP may contribute to tumorigenesis. This review assesses the current clinical and therapeutic characteristics of more than 200 FIPA families and addresses research findings among AIP mutation-bearing patients in different populations with pituitary adenomas.

Familial isolated pituitary adenomas: an emerging clinical entity

Familial pituitary tumors are increasingly recognized. While some of these cases are related to wellknown syndromic conditions such as multiple endocrine neoplasia type 1 (MEN1) or Carney complex, others belong to the familial isolated pituitary adenoma (FIPA) patient group. The discovery of heterozygous, loss-of-function germline mutations in the gene encoding the aryl hydrocarbon receptor interacting protein (AIP) in 2006 has subsequently enabled the identification of a mutation in this gene in 20% of FIPA families and 20% of childhood-onset simplex soma- totroph adenomas. The exact mechanism by which the lack of AIP leads to pituitary adenomas is not clear. AIP mutations cause a low penetrance autosomal dominant disease with often a distinct phenotype characterized by young-onset, aggressive, large GH, mixed GH and PRL or PRL-secreting adenomas. This review aims to summarize currently available clinical data on AIP mutation-positive and negative FIPA patients.

Genetic analysis in a patient presenting with meningioma and familial isolated pituitary adenoma (FIPA) reveals selective involvement of the R81X mutation of the AIP gene in the pathogenesis of the pituitary tumor

Familial isolated pituitary adenoma (FIPA), defined as the occurrence of at least two cases of pituitary adenoma in a family that does not exhibit features of syndromic diseases, such as Carney complex or Multiple Endocrine Neoplasia type 1 or 4, is a rare autosomal dominant disease with low penetrance. About 20 % of the families with FIPA harbor inactivating mutation in aryl hydrocarbon receptor-interacting protein gene (AIP) associated with loss of heterozygosity of the same genetic locus (11q13) in the tumor. Rarely different types of extra-pituitary tumors have been described in the setting of AIP mutation-positive FIPA. We present the case of a patient who was diagnosed with acromegaly due to the AIP mutation c.241C>T (p.R81X) at the age of 34 years, and treated by transsphenoidal surgery. At the age of 43 years she was diagnosed with a meningioma, and at age 46 had recurrence of the somatotropinoma. Genetic studies demonstrated loss of the normal allele (by sequencing and microsatellite analysis) in DNA from the pituitary adenoma but not from the meningioma, suggesting a selective involvement of AIP mutation in the pathogenesis of the pituitary adenoma, and a casual association with the meningioma. Further investigations are required to define the exact role of AIP in non-pituitary tumorigenesis.

Novel mutations in MEN1, CDKN1B and AIP genes in patients with multiple endocrine neoplasia type 1 syndrome in Spain

CONTEXT

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant disorder mostly owing to a genetic defect in MEN1 gene. Not all patients with MEN1 phenotype present a defect in this gene. Thus, other genes like CDKN and AIP have been showed to be involved in MEN1-like patients.

OBJECTIVE

The aim of this study was to perform a genetic screening in our cohort or patients with suspected MEN1 syndrome by direct sequencing analysis of MEN1, CDKN1B and AIP, and dosage analysis of MEN1 and AIP.

RESULTS

A total of 79 different sporadic and familial cases with the MEN1 phenotype have been studied, in which 34 of them (48%) present a mutation in MEN1 gene. In two patients without a detectable mutation in MEN1 gene, we have identified a novel missense mutation (c.163G>A/p.Ala55Thr) in CDKN1B gene and a novel frameshift mutation (c.825_845delCGCGGCCGTGTGGAATGCCCA/p. His275GlnfsX49) in AIP gene, respectively.

CONCLUSIONS

Our data support that MEN1 gene is the main target for genetic analysis in clinical MEN1 syndrome. We confirm that in those patients without MEN1 gene mutation, other genes such as CDKN1B/p27Kip, or AIP in those including pituitary tumours should also be tested.

Narrowing the gap of personalized medicine in emerging countries: the case of multiple endocrine neoplasias in Brazil

The finished version of the human genome sequence was completed in 2003, and this event initiated a revolution in medical practice, which is usually referred to as the age of genomic or personalized medicine. Genomic medicine aims to be predictive, personalized, preventive, and also participative (4Ps). It offers a new approach to several pathological conditions, although its impact so far has been more evident in mendelian diseases. This article briefly reviews the potential advantages of this approach, and also some issues that may arise in the attempt to apply the accumulated knowledge from genomic medicine to clinical practice in emerging countries. The advantages of applying genomic medicine into clinical practice are obvious, enabling prediction, prevention, and early diagnosis and treatment of several genetic disorders. However, there are also some issues, such as those related to: (a) the need for approval of a law equivalent to the Genetic Information Nondiscrimination Act, which was approved in 2008 in the USA; (b) the need for private and public funding for genetics and genomics; (c) the need for development of innovative healthcare systems that may substantially cut costs (e.g. costs of periodic medical followup); (d) the need for new graduate and postgraduate curricula in which genomic medicine is emphasized; and (e) the need to adequately inform the population and possible consumers of genetic testing, with reference to the basic aspects of genomic medicine.

Biochemical, bone and renal patterns in hyperparathyroidism associated with multiple endocrine neoplasia type 1

Primary hyperparathyroidism associated with multiple endocrine neoplasia type I (hyperparathyroidism/multiple endocrine neoplasia type 1) differs in many aspects from sporadic hyperparathyroidism, which is the most frequently occurring form of hyperparathyroidism. Bone mineral density has frequently been studied in sporadic hyperparathyroidism but it has very rarely been examined in cases of hyperparathyroidism/multiple endocrine neoplasia type 1. Cortical bone mineral density in hyperparathyroidism/multiple endocrine neoplasia type 1 cases has only recently been examined, and early, severe and frequent bone mineral losses have been documented at this site. Early bone mineral losses are highly prevalent in the trabecular bone of patients with hyperparathyroidism/multiple endocrine neoplasia type 1. In summary, bone mineral disease in multiple endocrine neoplasia type 1 related hyperparathyroidism is an early, frequent and severe disturbance, occurring in both the cortical and trabecular bones. In addition, renal complications secondary to sporadic hyperparathyroidism are often studied, but very little work has been done on this issue in hyperparathyroidism/multiple endocrine neoplasia type 1. It has been recently verified that early, frequent, and severe renal lesions occur in patients with hyperparathyroidism/multiple endocrine neoplasia type 1, which may lead to increased morbidity and mortality. In this article we review the few available studies on bone mineral and renal disturbances in the setting of hyperparathyroidism/multiple endocrine neoplasia type 1. We performed a meta-analysis of the available data on bone mineral and renal disease in cases of multiple endocrine neoplasia type 1-related hyperparathyroidism.

Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient little mice

OBJECTIVE

To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormone-releasing hormone receptors.

MATERIALS AND METHODS

The responses of serum growth hormone to acutely injected growth hormone-releasing P-2 in lit/lit mice, which represent a model of GH deficiency arising from mutated growth hormone-releasing hormone-receptors, were compared to those observed in the heterozygous (lit/+) littermates and wild-type (+/+) C57BL/6J mice.

RESULTS

After the administration of 10 mcg of growth hormone-releasing P-2 to lit/lit mice, a growth hormone release of 9.3±1.5 ng/ml was observed compared with 1.04±1.15 ng/ml in controls (p<0.001). In comparison, an intermediate growth hormone release of 34.5±9.7 ng/ml and a higher growth hormone release of 163±46 ng/ml were induced in the lit/+ mice and wild-type mice, respectively. Thus, GHRP-2 stimulated growth hormone in the lit/lit mice, and the release of growth hormone in vivo may be only partially dependent on growth hormone-releasing hormone. Additionally, the plasma leptin and ghrelin levels were evaluated in the lit/lit mice under basal and stimulated conditions.

CONCLUSIONS

Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2. The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a.

Adrenal lesions in acromegaly: do metabolic aspects and aryl hydrocarbon receptor interacting protein gene have a role? Evaluation at baseline and after long-term follow-up

BACKGROUND

Adrenal lesions are discovered in acromegaly more frequently than in general population, without relationship with primary disease. Some patients, carriers of aryl hydrocarbon receptor interacting protein (AIP) gene mutations, developed an adrenal neoplasm.

AIM

To evaluate the role of metabolic and genetic aspects and the follow-up of adrenal nodules in acromegaly.

MATERIAL AND METHODS

We studied 69 acromegalic patients (30 male and 39 female, 56 ± 15 yr) who had been referred to the Endocrinology Unit of Padua. In all patients we determined body mass index (BMI) and waist-to-hip ratio (WHR); we performed an oral glucose tolerance test (OGTT) whenever possible. If adrenal computed tomography revealed a lesion, the patient underwent an endocrine and genetic study.

RESULTS

Adrenal lesions were identified in 14 patients and were not related to gender, duration of disease, GH or IGF-I concentrations, basal and after-OGTT glucose and insulin levels, log(HOMA-IR) and Quantitative Insulin Sensitivity Check Index (QUICKI) values, whereas BMI and WHR were higher in patients with adrenal lesions. Baseline endocrine and radiological study revealed benign lesions; during mean 4-yr follow-up none of the patients showed hormone excess, even though some lesions increased in size. We did not find any mutation in AIP gene, except heterozygous silent alteration (T48T).

CONCLUSIONS

The frequency of non-functioning adrenal lesions in acromegaly is not associated with the considered aspects, except BMI and WHR. The prolonged follow-up showed that these lesions have a tendency to increase in size independently of the control of acromegaly, so a morphological follow- up is recommended.

Genetic susceptibility in pituitary adenomas: from pathogenesis to clinical implications

Pituitary adenomas usually present sporadically, with a multifactorial pathogenesis including somatic mutational events in cancer-related genes. Genetic predisposition implies the presence of germline DNA alterations with a range of impacts on pituitary cell biology, translating into a variable penetrance of the disease. Genetic causes must be considered in the presence of specific clinical settings, such as familial occurrence of pituitary adenoma, with or without extrapituitary diseases, and may also be suspected in young patients (<30 years of age) with macroadenomas. We review the clinical implications of genetic predisposition, with special attention on multiple endocrine neoplasia type 1, Carney complex and familial isolated pituitary adenoma. Genetic screening in selected patients with an apparently sporadic disease is also discussed.

Glucose-dependent insulinotropic peptide receptor overexpression in adrenocortical hyperplasia in MEN1 syndrome without loss of heterozygosity at the 11q13 locus

BACKGROUND

The molecular mechanisms involved in the genesis of the adrenocortical lesions seen in MEN1 syndrome (ACL-MEN1) remain poorly understood; loss of heterozygosity at 11q13 and somatic mutations of MEN1 are not usually found in these lesions. Thus, additional genes must be involved in MEN1 adrenocortical disorders. Overexpression of the glucose-dependent insulinotropic peptide receptor has been shown to promote adrenocortical tumorigenesis in a mice model and has also been associated with ACTH-independent Cushing syndrome in humans. However, to our knowledge, the status of glucose-dependent insulinotropic peptide receptor expression in adrenocortical lesions in MEN1 has not been previously investigated.

OBJECTIVE

To evaluate glucose-dependent insulinotropic peptide receptor expression in adrenocortical hyperplasia associated with MEN1 syndrome.

MATERIALS/METHODS

Three adrenocortical tissue samples were obtained from patients with previously known MEN1 germline mutations and in whom the presence of a second molecular event (a new MEN1 somatic mutation or an 11q13 loss of heterozygosity) had been excluded. The expression of the glucose-dependent insulinotropic peptide receptor was quantified by qPCR using the DDCT method, and b-actin was used as an endogenous control.

RESULTS

The median of glucose-dependent insulinotropic peptide receptor expression in the adrenocortical lesions associated with MEN1 syndrome was 2.6-fold (range 1.2 to 4.8) higher than the normal adrenal controls (p = 0.02).

CONCLUSION

The current study represents the first investigation of glucose-dependent insulinotropic peptide receptor expression in adrenocortical lesions without 11q13 loss of heterozygosity in MEN1 syndrome patients. Although we studied a limited number of cases of MEN1 adrenocortical lesions retrospectively, our preliminary data suggest an involvement of glucose-dependent insulinotropic peptide receptor overexpression in the etiology of adrenocortical hyperplasia. New prospective studies will be able to clarify the exact role of the glucose-dependent insulinotropic peptide receptor in the molecular pathogenesis of MEN1 adrenocortical lesions.