Anna Spada

Clinical characteristics and therapeutic responses in patients with Germ-line AIP mutations and pituitary adenomas : An international collaborative study

CONTEXT AIP mutations (AIPmut) give rise to a pituitary adenoma predisposition that occurs in familial isolated pituitary adenomas and less often in sporadic cases. The clinical and therapeutic features of AIPmut-associated pituitary adenomas have not been studied comprehensively. OBJECTIVE The objective of the study was to assess clinical/therapeutic characteristics of AIPmut pituitary adenomas. DESIGN This study was an international, multicenter, retrospective case collection/database analysis. SETTING The study was conducted at 36 tertiary referral endocrine and clinical genetics departments. PATIENTS Patients included 96 patients with germline AIPmut and pituitary adenomas and 232 matched AIPmut-negative acromegaly controls. RESULTS The AIPmut population was predominantly young and male (63.5%); first symptoms occurred as children/adolescents in 50%. At diagnosis, most tumors were macroadenomas (93.3%); extension and invasion was common. Somatotropinomas comprised 78.1% of the cohort; there were also prolactinomas (n = 13), nonsecreting adenomas (n = 7), and a TSH-secreting adenoma. AIPmut somatotropinomas were larger (P = 0.00026), with higher GH levels (P = 0.00068), more frequent extension (P = 0.018) and prolactin cosecretion (P = 0.00023), and occurred 2 decades before controls (P < 0.000001). Gigantism was more common in the AIPmut group (P < 0.000001). AIPmut somatotropinoma patients underwent more surgical interventions (P = 0.00069) and had lower decreases in GH (P = 0.00037) and IGF-I (P = 0.028) and less tumor shrinkage with somatostatin analogs (P < 0.00001) vs. controls. AIPmut prolactinomas occurred generally in young males and frequently required surgery or radiotherapy. CONCLUSIONS AIPmut pituitary adenomas have clinical features that may negatively impact treatment efficacy. Predisposition for aggressive disease in young patients, often in a familial setting, suggests that earlier diagnosis of AIPmut pituitary adenomas may have clinical utility.

Maternal and foetal resistin and adiponectin concentrations in normal and complicated pregnancies

Objective   The aim of this study was to evaluate how resistin and adiponectin (ApN) are involved in maternal energy metabolism and foetal growth.

Pseudohypoparathyroidism and GNAS Epigenetic Defects: Clinical Evaluation of Albright Hereditary Osteodystrophy and Molecular Analysis in 40 Patients

CONTEXT The two main subtypes of pseudohypoparathyroidism (PHP), PHP-Ia and -Ib, are caused by mutations in GNAS exons 1-13 and methylation defects in the imprinted GNAS cluster, respectively. PHP-Ia patients show Albright hereditary osteodystrophy (AHO) and resistance toward PTH and additional hormones, whereas PHP-Ib patients do not have AHO, and hormone resistance appears to be limited to PTH and TSH. Recently, methylation defects have been detected in few patients with PHP and mild AHO, indicating a molecular overlap between the two forms. OBJECTIVES The aim of the study was to screen patients with clinically diagnosed PHP-Ia for methylation defects and to investigate the presence of correlations between the molecular findings and AHO severity. PATIENTS AND METHODS We investigated differential methylation of GNAS regions and STX16 microdeletions in genomic DNA from 40 patients with sporadic AHO and multihormone resistance, with no mutations in Gsalpha-coding GNAS exons. RESULTS Molecular analysis showed GNAS cluster imprinting defects in 24 of the 40 patients analyzed. No STX16 deletion was detected. The presence of imprinting defects was not associated with the severity of AHO or with specific AHO signs. CONCLUSIONS We report the largest series of the literature of patients with clinical AHO and multihormone resistance and no mutation in the Gsalpha gene. Our findings of frequent GNAS imprinting defects further confirm the existence of an overlap between molecular and clinical features of PHP-Ia and PHP-Ib and highlight the necessity of a new clinical classification of the disease that takes into account the recent knowledge on the molecular basis underlying these defects.

High prevalence of AIP gene mutations following focused screening in young patients with sporadic pituitary macroadenomas

BACKGROUND Aryl hydrocarbon receptor interacting protein (AIP) mutations (AIPmut) cause aggressive pituitary adenomas in young patients, usually in the setting of familial isolated pituitary adenomas. The prevalence of AIPmut among sporadic pituitary adenoma patients appears to be low; studies have not addressed prevalence in the most clinically relevant population. Hence, we undertook an international, multicenter, prospective genetic, and clinical analysis at 21 tertiary referral endocrine departments. METHODS We included 163 sporadic pituitary macroadenoma patients irrespective of clinical phenotype diagnosed at <30 years of age. RESULTS Overall, 19/163 (11.7%) patients had germline AIPmut; a further nine patients had sequence changes of uncertain significance or polymorphisms. AIPmut were identified in 8/39 (20.5%) pediatric patients. Ten AIPmut were identified in 11/83 (13.3%) sporadic somatotropinoma patients, in 7/61 (11.5%) prolactinoma patients, and in 1/16 non-functioning pituitary adenoma patients. Large genetic deletions were not seen using multiplex ligation-dependent probe amplification. Familial screening was possible in the relatives of seven patients with AIPmut and carriers were found in six of the seven families. In total, pituitary adenomas were diagnosed in 2/21 AIPmut-screened carriers; both had asymptomatic microadenomas. CONCLUSION Germline AIPmut occur in 11.7% of patients <30 years with sporadic pituitary macroadenomas and in 20.5% of pediatric patients. AIPmut mutation testing in this population should be considered in order to optimize clinical genetic investigation and management.

Calcium-sensing receptor expression and signalling in human parathyroid adenomas and primary hyperplasia

Both in vivo and in vitro evidence indicates that primary hyperparathyroidism is characterized by a reduced sensitivity to extracellular calcium ([Ca2+]o). The existence of alterations in the expression and signalling of calcium sensing receptor (CaSR) in parathyroid neoplasia is still uncertain. In order to clarify the role of CaSR in the reduced [Ca2+]o sensing of parathyroid neoplasia we investigated PTH secretion and intracellular effectors triggered by CaSR activation as well as the levels of expression of CaSR and CaSR coupled G proteins (Gq/G11) in parathyroid adenomas and primary hyperplasia.

Dopamine-inhibited adenylate cyclase in female rat adenohypophysis

Abstract A dopamine-inhibited adenylate cyclase has been demonstrated in anterior pituitary gland of adult female rats, lactating and not lactating. This inhibitory effect was completely GTP dependent. In contrast, in the adenohypophysis of male rats, dopamine had no detectable effect on adenylate cyclase activity. In female rats the inhibition of the enzyme appears mediated by specific dopaminergic receptors: the effect of dopamine was mimicked by the dopaminergic agonists apomorphine and the ergot derivative CH 29–717, while norepinephrine was much less potent. On the other hand, the dopaminergic antagonists trifluoperazine and sulpiride competitively antagonized the dopamine inhibition of the adenylate cyclase. The possibility that the dopamine-inhibited enzyme is located in mammotrophs appears supported 1) by its observation in the female rat pituitary, which contains this type of cells in much larger proportion than the male gland (33–38% vs.

Proliferation of Transformed Somatotroph Cells Related to Low or Absent Expression of Protein Kinase A Regulatory Subunit 1A Protein

The two regulatory subunits (R1 and R2) of protein kinase A (PKA) are differentially expressed in cancer cell lines and exert diverse roles in growth control. Recently, mutations of the PKA regulatory subunit 1A gene (PRKAR1A) have been identified in patients with Carney complex. The aim of this study was to evaluate the expression of the PKA regulatory subunits R1A, R2A, and R2B in a series of 30 pituitary adenomas and the effects of subunit activation on cell proliferation. In these tumors, neither mutation of PRKAR1A nor loss of heterozygosity was identified. By real-time PCR, mRNA of the three subunits was detected in all of the tumors, R1A being the most represented in the majority of samples. By contrast, immunohistochemistry documented low or absent R1A levels in all tumors, whereas R2A and R2B were highly expressed, thus resulting in an unbalanced R1/R2 ratio. The low levels of R1A were, at least in part, due to proteasome-mediated degradation. The effect of the R1/R2 ratio on proliferation was assessed in GH3 cells, which showed a similar unbalanced pattern of R subunits expression, and in growth hormone-secreting adenomas. The R2-selective cAMP analog 8-Cl cAMP and R1A RNA silencing, stimulated cell proliferation and increased Cyclin D1 expression, respectively, in human and rat adenomatous somatotrophs. These data show that a low R1/R2 ratio promoted proliferation of transformed somatotrophs and are consistent with the Carney complex model in which R1A inactivating mutations further unbalance this ratio in favor of R2 subunits. These results suggest that low expression of R1A protein may favor cAMP-dependent proliferation of transformed somatotrophs.

Multiple endocrine neoplasia type 1 in patients with recognized pituitary tumours of different types

We have investigated the prevalence of MEN 1 in patients with recognized pituitary adenomas. Since hyperparathyroidism is present in nearly 95–100% of patients with MEN 1 and frequently is the first condition to be identified, the study was limited to the identification of patients with hyperparathyroidism while the screening for gastroenteropancreatic (GEP) lesions was carried out in patients with both pituitary and parathyroid lesions.

Ghrelin secretion in severely obese subjects before and after a 3-week integrated body mass reduction program

Ghrelin, the endogenous ligand of GH-secretagogue receptors, has been implicated in the regulation of feeding behavior and energy balance. Aim of the study was to investigate ghrelin levels in fasting conditions and after a standard meal test in obese subjects before and after a 3-week integrated body weight reduction (BWR) program (consisting of energyrestricted diet, exercise training, psychological counselling and nutritional education). Weight, height, fat mass, fat free mass (by impedentiometry), circulating ghrelin, insulin and leptin levels were evaluated in 10 obese subjects (3 male, 7 female; mean age: 35±9.3 yr; body mass index BMI: 45.2±10.6 kg/m2) before and after weight reduction. At baseline, obese subjects showed significantly lower ghrelin levels than controls, which were negatively correlated with BMI, weight, insulin and leptin levels. Fasting ghrelin levels were not modified by standard meal test in obese subjects (from 110.8±69.7 to 91.8±70.2 pmol/l p=ns), while a significant reduction was observed in controls (from 352.4±176.7 to 199.0±105.2 pmol/l; p<0.01). After a 3-week integrated BWR program obese subjects significantly reduced weight, BMI and leptin levels, while no significant changes were found both in fasting ghrelin and in ghrelin response after the meal. In conclusion, 5% weight loss obtained after a short-term period of integrated BWR program is not sufficient to normalize fasting ghrelin levels nor to restore the normal ghrelin suppression after a meal in severely obese subjects.

Genetics of Pituitary Tumors: Focus on G-Protein Mutations

In recent years the demonstration that human pituitary adenomas are monoclonal in origin has provided further evidence that pituitary neoplasia arise from the replication of a single mutated cell in which growth advantage results from either activation of proto-oncogenes or inactivation of tumor suppressor genes. While common oncogenes, such as Ras, are only exceptionally involved, the only mutations identified in a significant proportion of pituitary tumors, and particular in GH-secreting adenomas, occur in the Gsα gene (GNAS1) and cause constitutive activation of the cAMP pathway (gsp oncogene). Moreover, pituitary tumors overexpress hypothalamic releasing hormones, growth factors, and their receptors as well as cyclins involved in cell cycle progression. As far as the role of tumor suppressor genes in pituitary tumorigenesis is concerned, reduced expression of these genes seems to frequently occur in pituitary tumors as a consequence of abnormal methylation processes. Although the only mutational change so far identified in pituitary tumors is the gsp oncogene, this oncogene is not associated with a clear phenotype in patients bearing positive tumors. Mechanisms able to counteract the cAMP pathway, such as high sensitivity to somatostatin, and induction of genes with opposite actions, such as phosphodiesterases, CREB end ICER, or instability of mutant Gsα, have been proposed to account for the lack of genotype/phenotype relationships.