Significance of chromogranin A and synaptophysin in medullary thyroid carcinoma.

Medullary thyroid carcinoma (MTC) is a relatively rare thyroid carcinoma of C-cell deviation and produces and secrete calcitonin (CT) and chromogranin A (CgA) into the blood. Thus, both CT and CgA are immunohistochemical and serum markers for MTCs. MTC occurs in both sporadic and inheritable cases and the hallmark of inheritable cases in multiple endocrine neoplasm 2 (NEN2) is MTC. MEN2 cases represent 30% of MTCs through germline RET protooncogene mutation and occur in younger ages involving bilateral thyroid lobes. Sporadic cases are 70% of cases of solitary tumor and occur in older ages. CgA and synaptophysin (SPY) are the two, most widely used and reliable immunohistochemical markers for neuroendocrine tumors including MTCs. This study aimed to detect different immunohistochemical staining patterns for CgA and SPY between non-symptomatic small, microscopic lesions and invading larger aggressive tumors in both MEA2 cases and sporadic cases. There was different CgA and SPY immunostaining in MEA2 cases where small tumors (≤ 0.3 cm) were lesser immunostained for CgA and SPY, despite strong staining for CT, compared to the larger (≥ 0.5cm) tumors, stronger immunostained for CgA. There was also different CgA and SPY immunohistochemical staining in sporadic cases between small lesion (≤ 0.5 cm) and larger tumors (≥ 1.0cm). One small sporadic tumor (0.5 x 0.3 cm) was strongly and weakly, patchy (about 10% of tumor tissue) stained for CgA and SPY, respectively, while larger sporadic tumors were diffusely, stronger stained for CgA and SPY. Therefore, stronger CgA and SPY immunostaining for larger tumors in both MEA2 and sporadic cases may be used as independent aggressive immunohistochemical markers for MTCs.

Thymic Carcinoid as the First Manifestation of Multiple Endocrine Neoplasia Type 1 Syndrome: A Case Report and Review of the Literature.

The present study reported a rare case with thymic carcinoid as the first manifestation of multiple endocrine neoplasia type 1 (MEN1) syndrome, which presented with gene mutations of the MEN1 and glucokinase regulatory protein (GCKR). In this report, a 40-year-old male was diagnosed as MEN1 syndrome with thymic carcinoid, pancreatic cancer, hyperparathyroidism, and insulinoma with intrahepatic metastasis. Genetic testing showed the mutations of the MEN1 (c.378 G>A, p. Trp126*) in the patient, his children and two sisters, and GCKR (c.151C>T, p. Arg51*) gene in the patient and his children. The pathological examination showed that neuroendocrine tumor (NET) of the pancreas was characterized as 6 mitoses per 10 high-power fields (HPF), infiltration of adipose tissue, no intravascular tumor thrombus and nerve infiltration. In addition, NET of the liver was characterized as 4 mitoses per 10 HPF, no intravascular tumor thrombus and nerve infiltration. Immunohistochemical staining showed Ckpan (+), Syn (+), CgA (+), CD 56 (+), PGP 9.5 (+), and Ki67-positive cells (8-10%) in NET. Therefore, we suggested that genetic testing in family members of MEN1 patient, which may be helpful for early diagnosis.

Role of positron emission tomography imaging in Multiple Endocrine Neoplasia syndromes.

The aim of this review was to summarize the recent developments on the role of positron emission tomography (PET) imaging using different radiopharmaceuticals in patients with multiple endocrine neoplasia (MEN) syndromes. Although most guidelines do not mention the use of PET imaging in patients with MEN syndromes, recent data seem to suggest a relevant diagnostic role of PET imaging in this setting. In particular, latest evidence has shown that somatostatin receptor PET provides a diagnostic accuracy in detecting MEN syndromes-related neuroendocrine tumours (NETs) higher than that of somatostatin receptor scintigraphy, thus influencing patient management in a significant percentage of cases. 18 F-DOPA PET seems to have a potential role in detecting MEN-2-related NETs, whereas 18 F-FDG PET is potentially useful in identifying aggressive NETs with poorer outcomes. More studies are needed to better define the role of different radiotracer-based PET imaging in patients with MEN syndromes.

Association between neuroendocrine tumors biomarkers and primary tumor site and disease type based on total 68Ga-DOTATATE-Avid tumor volume measurements.

OBJECTIVE: To determine the association between neuroendocrine tumor (NET) biomarker levels and the extent of disease as assessed by 68Ga DOTATATE PET/CT imaging. DESIGN: A retrospective analysis of a prospective database of patients with NETs. METHODS: Fasting plasma chromogranin A (CgA), neuron-specific enolase (NSE), gastrin, glucagon, vasoactive intestinal peptide (VIP) and pancreatic polypeptide (PP), and 24-h urinary 5-hydroxyindoleacetic acid (5-HIAA) levels were measured. Correlation between biomarkers and total 68Ga-DOTATATE-avid tumor volume (TV) was analyzed. RESULTS: The analysis included 232 patients. In patients with pancreatic NETs (n = 112), 68Ga-DOTATATE TV correlated with CgA (r = 0.6, P = 0.001, Spearman). In patients with multiple endocrine neoplasia type 1 (n = 39), 68Ga-DOTATATE TV correlated with glucagon (r = 0.5, P = 0.01) and PP levels (r = 0.5, P = 0.049). In patients with von Hippel-Lindau (n = 24), plasma VIP (r = 0.5, P = 0.02) and PP levels (r = 0.7, P < 0.001) correlated with 68Ga-DOTATATE TV. In patients with small intestine NET (SINET, n = 74), 68Ga-DOTATATE TV correlated with CgA (r = 0.5, P = 0.02) and 5-HIAA levels (r = 0.7, P < 0.001), with 5-HIAA ≥8.1 mg/24 h associated with metastatic disease with high positive (81.8%) and negative (85.7%) predictive values (P = 0.001). 68Ga-DOTATATE TV in patients with NET of unknown primary (n = 16) and those with NET of other primary location (n = 30) correlated with 5-HIAA levels (r = 0.8, P = 0.002 and r = 0.7, P = 0.02 respectively). CONCLUSIONS: Our data supports the use of specific NET biomarkers based on the site of the primary NET and the presence of hereditary syndrome-associated NET. High urinary 5-HIAA levels indicate the presence of metastatic disease in patients with SINET.

Morphology, Biochemistry, and Pathophysiology of MENX-Related Pheochromocytoma Recapitulate the Clinical Features.

Pheochromocytomas (PCCs) are tumors arising from neural crest-derived chromaffin cells. There are currently few animal models of PCC that recapitulate the key features of human tumors. Because such models may be useful for investigations of molecular pathomechanisms and development of novel therapeutic interventions, we characterized a spontaneous animal model (multiple endocrine neoplasia [MENX] rats) that develops endogenous PCCs with complete penetrance. Urine was longitudinally collected from wild-type (wt) and MENX-affected (mutant) rats and outputs of catecholamines and their O-methylated metabolites determined by mass spectrometry. Adrenal catecholamine contents, cellular ultrastructure, and expression of phenylethanolamine N-methyltransferase, which converts norepinephrine to epinephrine, were also determined in wt and mutant rats. Blood pressure was longitudinally measured and end-organ pathology assessed. Compared with wt rats, mutant animals showed age-dependent increases in urinary outputs of norepinephrine (P = .0079) and normetanephrine (P = .0014) that correlated in time with development of tumor nodules, increases in blood pressure, and development of hypertension-related end-organ pathology. Development of tumor nodules, which lacked expression of N-methyltransferase, occurred on a background of adrenal medullary morphological and biochemical changes occurring as early as 1 month of age and involving increased adrenal medullary concentrations of dense cored vesicles, tissue contents of both norepinephrine and epinephrine, and urinary outputs of metanephrine, the metabolite of epinephrine. Taken together, MENX-affected rats share several biochemical and pathophysiological features with PCC patients. This model thus provides a suitable platform to study the pathogenesis of PCC for preclinical translational studies aimed at the development of novel therapies for aggressive forms of human tumors.

Basic Characteristics of Adults with Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Adenopathy Syndrome in Comparison with the Typical Pediatric Expression of Disease.

Autoinflammatory diseases are caused by inflammasome dysregulation leading to overproduction of proinflammatory cytokines and a pathological delay in the inflammation switching off. The progress of cellular biology has partially clarified pathogenic mechanisms behind monogenic autoinflammatory diseases, whereas little is known about the polygenic ones. Although the genetic susceptibility of periodic fever, aphthous stomatitis, pharyngitis, and adenopathy (PFAPA) syndrome is still obscure, the presence of overlapping symptoms with monogenic periodic fevers, the recurrence in family members, the important role played by dysregulated interleukin- (IL-) 1ß secretion during flares, the overexpression of inflammasome-associated genes during attacks, and, last but not least, the therapeutic efficacy of IL-1ß blockade strongly indicate a potential genetic involvement in its pathogenesis, probably linked with environmental factors. PFAPA syndrome has a typical inception in the pediatric age, but a delayed onset during adulthood has been described as well. Treatments required as well as effectiveness of tonsillectomy remain controversial, even if the disease seems to have a self-limited course mostly in children. The purpose of this review is to provide an overview of this complex polygenic/multifactorial autoinflammatory disorder in which the innate immune system undoubtedly plays a basic role.

Islet Cells Serve as Cells of Origin of Pancreatic Gastrin-Positive Endocrine Tumors.

The cells of origin of pancreatic gastrinomas remain an enigma, since no gastrin-expressing cells are found in the normal adult pancreas. It was proposed that the cellular origin of pancreatic gastrinomas may come from either the pancreatic cells themselves or gastrin-expressing cells which have migrated from the duodenum. In the current study, we further characterized previously described transient pancreatic gastrin-expressing cells using cell lineage tracing in a pan-pancreatic progenitor and a pancreatic endocrine progenitor model. We provide evidence showing that pancreatic gastrin-expressing cells, found from embryonic day 12.5 until postnatal day 7, are derived from pancreatic Ptf1a(+) and neurogenin 3-expressing (Ngn3(+)) progenitors. Importantly, the majority of them coexpress glucagon, with 4% coexpressing insulin, indicating that they are a temporary subpopulation of both alpha and beta cells. Interestingly, Men1 disruption in both Ngn3 progenitors and beta and alpha cells resulted in the development of pancreatic gastrin-expressing tumors, suggesting that the latter developed from islet cells. Finally, we detected gastrin expression using three human cohorts with pancreatic endocrine tumors (pNETs) that have not been diagnosed as gastrinomas (in 9/34 pNETs from 6/14 patients with multiple endocrine neoplasia type 1, in 5/35 sporadic nonfunctioning pNETs, and in 2/20 sporadic insulinomas), consistent with observations made in mouse models. Our work provides insight into the histogenesis of pancreatic gastrin-expressing tumors.

PTCH 1 staining of pancreatic neuroendocrine tumor (PNET) samples from patients with and without multiple endocrine neoplasia (MEN-1) syndrome reveals a potential therapeutic target.

Pancreatic neuroendocrine tumors (PNETs) are rare, indolent tumors that may occur sporadically or develop in association with well-recognized hereditary syndromes, particularly multiple endocrine neoplasia type 1 (MEN-1). We previously demonstrated that the hedgehog (HH) signaling pathway was aberrantly up-regulated in a mouse model that phenocopies the human MEN-1 syndrome, Men1l/l;RipCre, and that inhibition of this pathway suppresses MEN-1 tumor cell proliferation. We hypothesized that the HH signaling pathway is similarly upregulated in human PNETs. We performed immunohistochemical (IHC) staining for PTCH1 in human fresh and archival PNET specimens to examine whether human sporadic and MEN-1-associated PNETs revealed similar abnormalities as in our mouse model and correlated the results with clinical and demographic factors of the study cohort. PTCH1 staining was positive in 12 of 22 PNET patients (55%). Four of 5 MEN-1 patients stained for PTCH1 (p = 0.32 as compared with sporadic disease patients). Nine of 16 patients with metastatic disease stained for PTCH1 as compared with zero of 3 with localized disease only (p = 0.21). No demographic or clinical features appeared to be predictive of PTCH 1 positivity and PTCH 1 positivity per se was not predictive of clinical outcome. PTCH1, a marker of HH pathway up regulation, is detectable in both primary and metastatic tumors in more than 50% of PNET patients. Although no clinical or demographic factors predict PTCH1 positivity and PTCH1 positivity does not predict clinical outcome, the frequency of expression alone indicates that perturbation of this pathway with agents such as Vismodegib, an inhibitor of Smoothened (SMO), should be examined in future clinical trials.

p27 variant and corticotropinoma susceptibility: a genetic and in vitro study.

Germline mutations in p27(kip1) are associated with increased susceptibility to multiple endocrine neoplasias (MEN) both in rats and humans; however, the potential role of common polymorphisms of this gene in endocrine tumor susceptibility and tumorigenesis remains mostly unrecognized. To assess the risk associated with polymorphism rs2066827 (p27-V109G), we genotyped a large cohort of Brazilian patients with sporadic endocrine tumors (pituitary adenomas, n=252; pheochromocytomas, n=125; medullary thyroid carcinoma, n=51; and parathyroid adenomas, n=19) and 885 population-matched healthy controls and determined the odds ratios and 95% CIs. Significant associations were found for the group of patients with pituitary adenomas (P=0.01), particularly for those with ACTH-secreting pituitary adenomas (P=0.005). In contrast, no association was found with GH-secreting pituitary tumors alone or with the sporadic counterpart of MEN2-component neoplasias. Our in vitro analyses revealed increased colony formation and cell growth rate for an AtT20 corticotropin mouse cell line overexpressing the p27-V109G variant compared with cells transfected with the WT p27. However, the genotypic effects in genetic and in vitro approaches were divergent. In accordance with our genetic data showing specificity for ACTH-secreting pituitary tissues, the overexpression of p27-V109G in a GH3 somatotropin rat cell line resulted in no difference compared with the WT. Pituitary tumors are one of the major clinical components of syndromes associated with the p27 pathogenic mutations MENX and MEN4. Our genetic and in vitro data indicate that the common polymorphism rs2066827 may play a role in corticotropinoma susceptibility and tumorigenesis through a molecular mechanism not fully understood thus far.

Multiplicity of hormone-secreting tumors: common themes about cause, expression, and management.

CONTEXT: Multiplicity of hormone-secreting tumors occurs in a substantial portion of hormone-excess states. Multiplicity increases the difficulty of management and drives the selection of special strategies. EVIDENCE ACQUISITION: This is a synthesis from publications about tumor development and expression, and also about types of clinical strategy for hormone-secreting tumors. EVIDENCE SYNTHESIS: Comparisons were made between patient groups with solitary tumors vs those with multiple tumors. Major themes with clinical relevance emerged. Usually, tumor multiplicity develops from a genetic susceptibility in all cells of a tissue. This applies to hormone-secreting tumors that begin as either polyclonal (such as in the parathyroids of familial hypocalciuric hypercalcemia) or monoclonal tumors (such as in the parathyroids of multiple endocrine neoplasia type 1 [MEN1]). High penetrance of a hereditary tumor frequently results in bilaterality and in several other types of multiplicity. Managements are better for the hormone excess than for the associated cancers. Management strategies can be categorized broadly as ablation that is total, subtotal, or zero. Examples are discussed for each category, and 1 example of each category is named here: 1) total ablation of the entire tissue with effort to replace ablated functions (for example, in C-cell neoplasia of multiple endocrine neoplasia type 2); 2) subtotal ablation with increased likelihood of persistent disease or recurrent disease (for example, in the parathyroid tumors of MEN1); or 3) no ablation of tissue with or without the use of pharmacotherapy (for example, with blockers for secretion of stomach acid in gastrinomas of MEN1). CONCLUSIONS: Tumor multiplicity usually arises from defects in all cells of the precursor tissue. Even the optimized managements involve compromises. Still, an understanding of pathophysiology and of therapeutic options should guide optimized management.

A novel mutation in the upstream open reading frame of the CDKN1B gene causes a MEN4 phenotype.

The CDKN1B gene encodes the cyclin-dependent kinase inhibitor p27(KIP1), an atypical tumor suppressor playing a key role in cell cycle regulation, cell proliferation, and differentiation. Impaired p27(KIP1) expression and/or localization are often observed in tumor cells, further confirming its central role in regulating the cell cycle. Recently, germline mutations in CDKN1B have been associated with the inherited multiple endocrine neoplasia syndrome type 4, an autosomal dominant syndrome characterized by varying combinations of tumors affecting at least two endocrine organs. In this study we identified a 4-bp deletion in a highly conserved regulatory upstream ORF (uORF) in the 5'UTR of the CDKN1B gene in a patient with a pituitary adenoma and a well-differentiated pancreatic neoplasm. This deletion causes the shift of the uORF termination codon with the consequent lengthening of the uORF-encoded peptide and the drastic shortening of the intercistronic space. Our data on the immunohistochemical analysis of the patient's pancreatic lesion, functional studies based on dual-luciferase assays, site-directed mutagenesis, and on polysome profiling show a negative influence of this deletion on the translation reinitiation at the CDKN1B starting site, with a consequent reduction in p27(KIP1) expression. Our findings demonstrate that, in addition to the previously described mechanisms leading to reduced p27(KIP1) activity, such as degradation via the ubiquitin/proteasome pathway or non-covalent sequestration, p27(KIP1) activity can also be modulated by an uORF and mutations affecting uORF could change p27(KIP1) expression. This study adds the CDKN1B gene to the short list of genes for which mutations that either create, delete, or severely modify their regulatory uORFs have been associated with human diseases.

Characterization of MENX-associated pituitary tumours.

AIMS: The aim of this study is to evaluate the pathological features, serum hormone levels and ex vivo cultures of pituitary adenomas that occur in rats affected by MENX syndrome. MENX is multiple endocrine neoplasia syndrome caused by a germline mutation in the cell cycle inhibitor p27. Characterization of MENX adenomas is a prerequisite to exploit this animal model for molecular and translational studies of pituitary adenomas. METHODS: We investigated MENX pituitary adenomas with immunohistochemistry, double immunofluorescence, electron microscopy, reverse transcription polymerase chain reaction (RT-PCR), measurement of serum hormone levels and ex vivo cultures. RESULTS: Adenomas in MENX rats belong to the gonadotroph lineage. They start from 4 months of age as multiple neoplastic nodules and progress to become large lesions that efface the gland. Adenomas are composed of chromophobic cells predominantly expressing the glycoprotein alpha-subunit (αGSU). They show mitotic activity and high Ki67 labelling. A few neoplastic cells co-express gonadotropins and the transcription factor steroidogenic factor 1, together with growth hormone or prolactin and Pit-1, suggesting that they are not fully committed to one cell lineage. Ex vivo cultures show features similar to the primary tumour. CONCLUSIONS: Our results suggest that p27 function is critical to regulate gonadotroph cells growth. The MENX syndrome represents a unique model to elucidate the physiological and molecular mechanisms mediating the pathogenesis of gonadotroph adenomas.

Acromegaly caused by growth hormone releasing hormone (GHRH) secreting tumor in multiple endocrine neoplasia (MEN-1).

We are presenting the clinical features, diagnostic work up and treatment of acromegaly caused by Growth hormone releasing hormone (GHRH) secreting neuroendocrine tumor (NECT) in a case of multiple endocrine neoplasia type 1 (MEN-1). A 36 year old man, known case of MEN-1 presented with acromegalic features. He has high IGF-1, GH and very high GHRH levels with a pancreatic head tumor and pituitary mass. He had high GHRH arteriovenous gradient across pancreatic tumor and underwent tumor resection, Post operative GHRH level fell dramatically. Tumor had high GHRH m-RNA level. Acromegalic patients with MEN-1 should be screened for ectopic GHRH secretion. Measurement of GHRH arteriovenous gradient across NECT or mRNA for GHRH in resected tumor can confirm the ectopic source. Treatment of choice is surgical resection of the tumor. Somatostatin analogue is an alternative because of its dual action in the pituitary gland and the NECT. Life long surveillance is needed as recurrence chance is high.

Molecular pathology and genetics of pancreatic endocrine tumours.

Pancreatic neuroendocrine tumours (PETs) are the second most frequent pancreatic neoplasms. Their poor chemosensitivity, high rate of metastatic disease and relatively long survival make PETs an ideal field to be explored for novel therapies based on specific molecular changes. PETs are generally sporadic but can also arise within hereditary syndromes, such as multiple endocrine neoplasia type 1, von Hippel-Lindau, neurofibromatosis type 1 and tuberous sclerosis complex, which represent a model for sporadic cases too. Among allelic imbalances, main genomic changes involve gain of 17q, 7q and 20q and loss of 11q, 6q and 11p, which identify regions of putative candidate oncogenes or tumour suppressor genes (TSGs), respectively, sometime with potential prognostic significance. Overexpression of Src-like kinases and cyclin D1 (CCND1) oncogene has been described. As for TSGs, P53 (TP53), DPC4/SMAD4 and RB (RB1) are not implicated in PET tumorigenesis, while for p16INK4a (CDKN2A), TIMP3, RASSF1A and hMLH1, more data are available, suggesting a role for methylation as a silencing mechanism. In the last decade, gene expression profile studies, analysis of microRNAs and, more recently, large-scale mutational analysis have highlighted commonly altered molecular pathways in the pathology of PETs. The roles of the mammalian target of rapamycin pathway, and its connection with Src kinases, and the activity of a number of tyrosine kinase receptors seem to be pivotal, as confirmed by the results of recent clinical trials with targeted agents. Mutations of DAXX and ATRX are common and related to altered telomeres but not to prognosis.

In vitro studies of novel PRKAR1A mutants that extend the predicted RIα protein sequence into the 3'-untranslated open reading frame: proteasomal degradation leads to RIα haploinsufficiency and Carney complex.

BACKGROUND: Carney complex (CNC) is a multiple endocrine neoplasia syndrome due to inactivating mutations in the PRKAR1A gene that codes for type Iα regulatory (RIα) subunit of protein kinase A. Most PRKAR1A mutations are subject to nonsense mRNA decay (NMD) and, thus, lead to haploinsufficiency. METHODS AND SETTING: Patient phenotyping for CNC features and DNA, RNA, protein, and transfection studies were carried out at a research center. RESULTS: We describe in unrelated kindreds with CNC four naturally occurring PRKAR1A mutations (1055del4, 1067del4ins5, 1076delTTins13, and 1142del4) that are predicted to escape NMD because they are located in the last coding exon of the gene. The phenotype of CNC was not different from that in other patients with the condition, although the number of patients was small. Each of the mutations caused a frameshift that led to a new stop codon into the 3' untranslated open reading frame, predicting an elongated protein that, however, was absent in patient-derived cells. After site-directed mutagenesis, in vitro transcription, and cell-free translation experiments, the expected size mutant proteins were present. However, when the mutant constructs were transfected in adrenal (NCI-295), testicular (N-TERA), and embryonic (HEK293) cells and despite the presence of the mutant mRNA, Western blot analysis indicated that there were no longer proteins. The subsequent application of proteasome inhibitors to cells transfected with the mutant constructs led to the detection of the aberrant proteins, although a compound that affects protein folding had no effect. The wild-type protein was also decreased in both patient-derived cells and/or tissues as well as in the in vitro systems used in this study. CONCLUSIONS: This was the first demonstration of proteasomal degradation of RIα protein variants leading to PRKAR1A haploinsufficiency and CNC, adding protein surveillance to NMD in the cellular mechanisms overseeing RIα synthesis. In agreement with the molecular data, CNC patients bearing PRKAR1A defects that extend the open reading frame did not have a different phenotype, although this has to be confirmed in a larger number of patients.

Levels of p27 sensitize to dual PI3K/mTOR inhibition.

Constitutive activation of the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling cascade occurs in a variety of human malignancies, where it sustains tumor cell proliferation and survival. Pharmacologic blockade of this pathway exerts antineoplastic activity by triggering apoptosis and/or cell-cycle arrest. Pituitary adenomas show activation of the PI3K/AKT/mTOR pathway, but only a fraction of them respond in vitro to the antiproliferative action of rapamycin and RAD001 (mTOR inhibitors), possibly because of the described negative feedback loop on AKT which reactivates the signaling cascade. Rats affected by the multiple endocrine neoplasia-like syndrome (MENX) develop pituitary adenomas showing increased activated AKT. In this study, we comparatively investigated the antitumor potential of the novel dual PI3K/mTOR inhibitor NVP-BEZ235 and the single mTOR inhibitor RAD001 on rat pituitary adenoma cells in primary culture. NVP-BEZ235 inhibits the PI3K pathway both upstream and downstream of AKT, thereby preventing the negative feedback loop. NVP-BEZ235 was more effective than RAD001 in reducing cell viability of pituitary adenomas. Consistently, NVP-BEZ235 treatment decreased Akt and S6 phosphorylation and triggered apoptosis. Because MENX is caused by a germline loss-of-function mutation in the cell-cycle inhibitor p27Kip1, we investigated the relationship between this defect and response to NVP-BEZ235 treatment. The levels of p27Kip1 positively correlate with the response to NVP-BEZ235 treatment. Combined treatment with NVP-BEZ235 and the proteasome inhibitor bortezomib, which increases p27Kip1 amount, shows synergistic antiproliferative effects on pituitary adenoma cells. Our data suggest that NVP-BEZ235 may represent an effective therapeutic modality for pituitary adenomas and that p27Kip1 levels represent a potential predictor of response to dual PI3K/mTOR inhibition.

Adrenal cortical tumors, pheochromocytomas and paragangliomas.

Distinguishing adrenal cortical adenomas from carcinomas may be a difficult diagnostic problem. The criteria of Weiss are very useful because of their reliance on histologic features. From a practical perspective, the most useful criteria to separate adenomas from carcinomas include tumor size, presence of necrosis and mitotic activity including atypical mitoses. Adrenal cortical neoplasms in pediatric patients are more difficult to diagnose and to separate adenomas from carcinomas. The diagnosis of pediatric adrenal cortical carcinoma requires a higher tumor weight, larger tumor size and more mitoses compared with carcinomas in adults. Pheochromocytomas are chromaffin-derived tumors that develop in the adrenal gland. Paragangliomas are tumors arising from paraganglia that are distributed along the parasympathetic nerves and sympathetic chain. Positive staining for chromogranin and synaptophysin is present in the chief cells, whereas the sustentacular cells are positive for S100 protein. Hereditary conditions associated with pheochromocytomas include multiple endocrine neoplasia 2A and 2B, Von Hippel-Lindau disease and neurofibromatosis I. Hereditary paraganglioma syndromes with mutations of SDHB, SDHC and SDHD are associated with paragangliomas and some pheochromocytomas.

Glucagon expression in cystic pancreatic neuroendocrine neoplasms: an immunohistochemical analysis.

Pancreatic neuroendocrine neoplasms (P-NENs) are usually solid and only rarely cystic. Glucagon expression and the association with multiple endocrine neoplasia type 1 (MEN1) seem to be common in cystic P-NENs. In this study, we analyzed 404 P-NENs to gain information about the relative frequency of grossly cystic P-NENs and their association with glucagon production by the tumor cells. Three hundred forty-six solitary P-NENs and 58 P-NENs (>1 cm in diameter) from 35 patients with an MEN1 syndrome were studied. Immunostaining was performed for the four pancreatic hormones; 5.5% (19/346) of the sporadic P-NENs showed unilocular or multilocular cystic changes that were macroscopically detectable. Sixty-three percent of the solitary cystic P-NENs (versus 7% of the solitary non-cystic P-NENs) expressed predominantly glucagon. In MEN1-associated P-NENs, the relative frequency of cystic tumors was 10.3%, and all of them expressed glucagon. None of the glucagon-positive cystic P-NENs were associated with a glucagonoma syndrome. Solitary non-MEN1-associated and MEN1-associated cystic P-NENs are predominantly non-syndromic glucagon-expressing tumors. However, cystic insulinomas may also occur. Cyst formation seems to be related to hormone production.

MEN-4 and other multiple endocrine neoplasias due to cyclin-dependent kinase inhibitors (p27(Kip1) and p18(INK4C)) mutations.

Cyclin-dependent kinase inhibitors (CDKIs) are known targets to become deregulated in various tumour types, including endocrine tumours. Typically, these cell cycle regulators are somatically inactivated in sporadic endocrine tumours. Recently, it became known that certain CDKI genes cause inherited susceptibility to endocrine neoplasia. Multiple endocrine neoplasia type 4 (MEN4) emerged as a novel form of multiple endocrine neoplasia, caused by mutations in the CDKI gene CDKN1B/p27(Kip1). The MEN4 phenotype remains unclear, but all MEN4 patients identified thus far present with parathyroid involvement, and less typically with pituitary adenomas and other endocrine features. Moreover, the CDKI gene CDKN2C/p18(INK4C) has been also implicated in endocrine neoplasia susceptibility. This review presents the recent advances in these novel MEN-related states and summarises the current knowledge of how these CDKIs may be implicated in endocrine neoplasia. In addition, it briefly presents data from Cdkn1b/p27(Kip1) and Cdkn2c/p18(INK4C) murine models, which strongly support the protective role of these inhibitors against endocrine tumourigenesis.