Identification and characterization of the multiple endocrine neoplasia type 1 (MEN1) gene

Sporadic Parathyroid Carcinoma Treated With Lenvatinib, Exhibiting a Novel Somatic MEN1 Mutation

Parathyroid carcinoma (PC) is extremely rare and is primarily treated surgically. Chemotherapy is an option for advanced stages, but no standard regimen exists. Emerging research suggests the efficacy of multitarget tyrosine kinase inhibitors (MTKIs) for PC, targeting vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR). A 61-year-old Japanese woman presented with a neck mass, diagnosed as PC with pleural and lumbar metastases. After parathyroidectomy and radiation for lumbar metastasis, immunohistochemistry showed VEGFR overexpression, leading to targeted therapy with MTKIs. Despite no actionable mutations on cancer genomic panel test, a novel MEN1 somatic mutation (NM_130801: exon2: c.332delG: p.G111fs*8) was identified, which may affect VEGFR2 expression and tumor epigenetics. Although severe hand-foot syndrome necessitated dose reductions and treatment interruptions, sorafenib treatment managed hypercalcemia with evocalcet and denosumab. Lenvatinib, as second-line therapy, was effective against pleural metastases but caused thrombocytopenia and hematuria, leading to discontinuation and uncontrolled recurrence and metastasis progression. Our case highlights the need for further research on genomic profiling, molecular targets, and therapy response in PC.

Multiple endocrine neoplasia type 1 combined with thyroid neoplasm: A case report and review of literatures

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is a rare hereditary tumor syndrome inherited in an autosomal dominant manner and presents mostly as parathyroid, endocrine pancreas (such as gastrinoma) and anterior pituitary tumors. At present, papillary thyroid carcinoma (PTC) and nodular goiter are not regarded as components of MEN1.

CASE SUMMARY

A 35-year-old woman presented with MEN1 accompanied by coinstantaneous PTC and nodular goiter. The pathological diagnosis was PTC with cervical lymph node metastasis, nodular goiter, parathyroid cyst and adenomatoid hyperplasia. Genetic testing was performed and a MEN1 gene mutation was detected. The patient underwent unilateral lobectomy of the thyroid gland and surgical removal of the parathyroid tumors. At 18 mo of follow-up, ultrasonic examination of the neck showed no abnormality. Serum calcium and parathyroid hormone levels were normal. No new MEN1-associated tumors were detected.

CONCLUSION

The role of inactivating mutations of MEN1 gene in tumorigenesis of PTC and/or nodular goiter remains to be determined by more case reports and further research.

The Mechanisms Underlying Autonomous Adrenocorticotropic Hormone Secretion in Cushing's Disease

Cushing’s disease caused due to adrenocorticotropic hormone (ACTH)-secreting pituitary adenomas (ACTHomas) leads to hypercortisolemia, resulting in increased morbidity and mortality. Autonomous ACTH secretion is attributed to the impaired glucocorticoid negative feedback (glucocorticoid resistance) response. Interestingly, other conditions, such as ectopic ACTH syndrome (EAS) and non-neoplastic hypercortisolemia (NNH, also known as pseudo-Cushing’s syndrome) also exhibit glucocorticoid resistance. Therefore, to differentiate between these conditions, several dynamic tests, including those with desmopressin (DDAVP), corticotrophin-releasing hormone (CRH), and Dex/CRH have been developed. In normal pituitary corticotrophs, ACTH synthesis and secretion are regulated mainly by CRH and glucocorticoids, which are the ACTH secretion-stimulating and -suppressing factors, respectively. These factors regulate ACTH synthesis and secretion through genomic and non-genomic mechanisms. Conversely, glucocorticoid negative feedback is impaired in ACTHomas, which could be due to the overexpression of 11β-HSD2, HSP90, or TR4, or loss of expression of CABLES1 or nuclear BRG1 proteins. Genetic analysis has indicated the involvement of several genes in the etiology of ACTHomas, including USP8, USP48, BRAF, and TP53. However, the association between glucocorticoid resistance and these genes remains unclear. Here, we review the clinical aspects and molecular mechanisms of ACTHomas and compare them to those of other related conditions.

Paediatric and young adult manifestations and outcomes of multiple endocrine neoplasia type 1

CONTEXT

Multiple endocrine neoplasia 1 (MEN 1) is an autosomal dominant disease presenting as hyperplasia and neoplasia of parathyroid, pituitary and enteropancreatic tissues. Over 90% of gene carriers develop phenotypic disease by age 30 years, potentially with onset of asymptomatic disease during childhood and adolescence.

OBJECTIVE

To describe the paediatric and young adult manifestations of MEN 1.

DESIGN

Descriptive retrospective study of 180 patients with a common MEN1 genotype. The paediatric and young adult (age <22 years) manifestations were determined using hospital records and disease surveillance data.

RESULTS

Primary hyperparathyroidism (PHPT) was identified in 42 patients (mean age 17.2 ± 3.3 years). Parathyroidectomy was performed in 16 (38.1%; mean age 17.8 ± 3.2). Four patients experienced recurrent PHPT (25%), and six (37.5%) developed permanent hypoparathyroidism. Pituitary disease was identified in 13 patients. Prolactinoma was found in nine patients (mean age 16.6 ± 2.6 years) of whom four (44.4%) had macroprolactinoma. Two patients required surgical intervention; dopamine agonists showed efficacy in six patients. Two patients with Cushing's disease were successfully treated surgically. Three patients with nonfunctioning pituitary microadenoma managed conservatively. Pancreatic neuroendocrine neoplasms (pNENs) were diagnosed in 12 patients (mean age 17.0 ± 2.6 years): three patients with insulinoma successfully resected (two resected and one exhibiting perineural invasion) and nine patients with nonfunctioning adenomas (NFAs).

CONCLUSION

Pituitary adenomas, PHPT and pNENs are encountered in the paediatric and young adult MEN 1 population. Successful outcomes are typically achieved using standard medical and surgical paradigms; however, parathyroidectomy was associated with a substantial complication rate.

Two nonsense somatic mutations in MEN1 identified in sporadic insulinomas

Insulinomas are functional pancreatic neuroendocrine tumors that cause hypoglycemia and severe morbidity. The aim of our study was to identify gene mutations responsible for tumorigenesis of sporadic insulinoma. Whole exome sequencing analysis was performed on tumors and paired peripheral blood from three patients with insulinomas. After initial analysis, somatic mutations were obtained and a deleterious protein product was further predicted by various bioinformatic programs. Whole exome sequencing identified 55 rare somatic mutations among three insulinoma patients, including MEN1 gene nonsense mutations (c. 681C>G; p.Tyr227* in exon 4 of MEN1 and c. 346G>T; p.Glu116* in exon 2 of MEN1) in two different tumor samples. The mutations resulted in a significant truncation of the protein and a non-functional gene product, which was involved in defective binding of menin to proteins implicated in genetic and epigenetic mechanisms. Our results extend the growing list of pathogenic MEN1 mutations in sporadic cases of insulinoma.

Germline and somatic genetic changes in multicentric tumors obtained from a patient with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary cancer syndrome caused by germline mutations of the MEN1 gene located in chromosome 11q13. In patients with MEN1, multicentric tumors develop in the involved organs; however, precise evaluation of genetic changes in these multicentric tumors has not been performed. In the present study, using whole-exome sequencing, we analyzed germline and somatic genetic changes in blood cells, two pancreatic endocrine tumors and one duodenal tumor obtained from a patient with MEN1 gastrinoma. We found that this patient possessed a novel germline mutation of the MEN1 gene [NM_137099.2:c.1505dupA (p.Lys502Lysfs); the localization was Chr11:64572134 on Assembly GRCh37], in which an adenine insertion in codon 502 of the MEN1 gene resulted in a frame shift and a premature stop codon. In terms of heterozygosity, the mutated allele was heterozygous in blood cells, hemizygous in the two pancreatic tumors and homozygous in the duodenal tumor. Immunohistochemical staining confirmed that only truncated menin protein accumulated in the nucleus of the tumor tissues. Further evaluation of tumor-specific somatic mutations in two pancreatic tumors did not detect single-nucleotide variations (SNVs) in 609 cancer-associated genes designated by the COSMIC cancer gene census, suggesting that the germline MEN1 mutation and resultant loss of heterozygosity played a major role in tumorigenesis. In the duodenal tumor, in addition to the germline MEN1 mutation, single-nucleotide variations in two cancer-associated genes were found. Further studies are required to clarify the role of these somatic single-nucleotide variations in the progression of MEN1 tumors.

Multiple Endocrine Neoplasia Type-I-like Syndrome in Two Cats

Multiple endocrine neoplasia (MEN) embodies a group of diseases in human patients and domestic animals that are characterized by hyperplasia or neoplasia, or both, of two or more endocrine tissues. The MEN-1 syndrome is associated with menin gene mutations that induce various combinations of parathyroid, pituitary, and pancreatic endocrine tumors in humans. Two male, Domestic Shorthair cats developed symmetric alopecia, insulin-resistant diabetes mellitus, and pituitary-dependent hyperadrenocorticism at 12 and 13 years of age. Examination of skin biopsy specimens revealed atrophic dermatosis associated with hyperadrenocorticism. In one cat, cutaneous lesions consistent with paraneoplastic alopecia associated with pancreatic adenocarcinoma also were evident. Multiple invasive pancreatic beta cell carcinomas, pituitary corticotroph adenomas, and thyroid C-cell and parathyroid chief cell hyperplasia were diagnosed on the basis of results of gross, histologic, and immunohistochemical findings in both cats. Pancreatic exocrine adenocarcinoma was diagnosed in both cats. one cat also had hepatocellular carcinoma. Exons 1-8 of the feline menin gene were sequenced and were found to bear 93% homology with the human gene sequence, and the corresponding amino acid sequences shared 98% homology. Purification of total RNA and amplification of cDNA from lesional tissues to document mutations in the feline menin gene sequence were unsuccessful. The combination of lesions observed was consistent with the diagnosis of MEN-1-like syndrome in both cats.

[Pancreatic neuroendocrine tumours. What do we know of their history?]

Starting with Paul Langerhans, who first described pancreatic islets in 1869, this article reviews the various protagonists who, in the last century and a half, have contributed to the discovery of the main hormones originating in the pancreas, the analytical methods for their measurement, the imaging techniques for identifying tumoural location, and the various pancreatic neoplasms.

Novel MEN 1 gene findings in rare sporadic insulinoma--a case control study

BACKGROUND

Insulinomas, which are rare tumors causing hyperinsulinemic hypoglycemia are usually sporadic but may also occur in association with multiple endocrine neoplasia type 1 (MEN-1) syndrome an autosomal dominant disorder caused by MEN1 gene mutations. MEN1 encodes a nuclear protein Menin, a tumor suppressor which acts as an adapter and interacts with partner proteins involved in crucial activities like transcriptional regulation, cell division, proliferation and genome stability. This study reports on clinical findings and mutation screening in sporadic insulinoma patients.

METHODS

Seventeen patients diagnosed with insulinoma were recruited along with 30 healthy volunteers who acted as controls for the present study. The patients presented with symptoms of sweating, tremors, drowsiness, palpitations, loss of consciousness, abnormal behavior, seizures and weight gain. Detailed clinical and family history was collected from all the participants along with 5 ml of blood sample after taking informed consent. Genomic DNA isolated from blood was subjected to MEN1 gene amplification followed by direct sequencing. Nucleotide sequences obtained were compared with published MEN1 cDNA sequences. Prediction of functional effects of novel changes was done using various bioinformatics algorithms.

RESULTS

Molecular analysis revealed presence of three novel exonic mutations (M561K, Q192K and Q261Q), two novel intronic variations c.445-44G → A and c.913-42G → C in introns two and six respectively and three reported exon SNPs; H433H (rs540012), D418D (rs2071313), A541T (rs2959656) and one intronic SNP (rs669976).

CONCLUSIONS

The study identified presence of novel pathogenic MEN1 mutations in sporadic cases of insulinoma. The new mutations identified were in regions involved in defective binding of menin to proteins implicated in genetic and epigenetic mechanisms. The outcome of the study extends the growing list of MEN1 pathogenic mutations even in sporadic cases providing consequential insight into phenotypic heterogeneity and in the expression of individual mutations.

The role of genetic and epigenetic changes in pituitary tumorigenesis

Pituitary adenomas are one of the most common intracranial tumors. Despite their benign nature, dysregulation of hormone secretion causes systemic metabolic deterioration, resulting in high mortality and an impaired quality of life. Tumorigenic pathogenesis of pituitary adenomas is mainly investigated by performing genetic analyses of somatic mutations in the tumor or germline mutations in patients. Genetically modified mouse models, which develop pituitary adenomas, are also used. Genetic analysis in rare familial pituitary adenomas, including multiple endocrine neoplasia type 1 and type 4, Carney complex, familial isolated pituitary adenomas, and succinate dehydrogenases (SDHs)-mediated paraganglioma syndrome, revealed several causal germline mutations and sporadic somatic mutations in these genes. The analysis of genetically modified mouse models exhibiting pituitary adenomas has revealed the underlying mechanisms, where cell cycle regulatory molecules, tumor suppressors, and growth factor signaling are involved in pituitary tumorigenesis. Furthermore, accumulating evidence suggests that epigenetic changes, including deoxyribonucleic acid (DNA) methylation, histone modification, micro ribonucleic acids (RNAs), and long noncoding RNAs play a pivotal role. The elucidation of precise mechanisms of pituitary tumorigenesis can contribute to the development of novel targeted therapy for pituitary adenomas.

Genetic and epigenetic analysis in korean patients with multiple endocrine neoplasia type 1

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN1) is a familial syndrome characterized by the parathyroid, pancreas and pituitary tumors. Parathyroid tumors are the most common clinical manifestations, occurring in more than 90% of MEN1 patients. Heterozygous germline mutations of the MENIN gene underlie the tumorigenesis in MEN1 and epigenetic alterations along with germline mutations may contribute to tumorigenesis. Here, we investigated the associations between genotype and phenotype in Korean MEN1 patients.

METHODS

We analyzed medical records from 14 unrelated MEN1 patients who had newly confirmed MENIN germline mutations, together with 14 previous reports in Korea. Aberrant DNA methylations were also examined in MEN1-related parathyroid tumors using the Infinium HumanMethylation 450 BeadChip.

RESULTS

Total 28 germline mutations of MENIN were relatively highly concentrated in exons 7 and 8 compared to previous reports from Western countries. Six mutations (c.111dupT/p.S38Ffs(*)79, c.225_226insT/p.T76Yfs(*)41, c.383_398del16/p.S128Tfs(*)52, c.746dupT/p.H250Afs(*)20, c.1150G>T/p.E384(*), and c.1508G>A/p.G503N) were newly found in the present study. Of interest, four patients (15%) showed unusual initial presentations and three patients were diagnosed incidentally at the general medical checkup. We also found three distinct sites in exon 2 of MENIN were significantly hypomethylated in the MEN1 parathyroid tumors, comparing correspondent blood samples.

CONCLUSION

We also have found a lack of genotype/phenotype correlation in Korean MEN1 patients. There were not a few unusual initial manifestations in MEN1 patients, thus, genetic testing for the MENIN germline mutations can provide important information for the better prognosis. Further studies are warranted to investigate altered DNA methylations in the MENIN gene involved in tumorigenesis.

Trithorax complex component Menin controls differentiation and maintenance of T helper 17 cells

Epigenetic modifications, such as posttranslational modifications of histones, play an important role in gene expression and regulation. These modifications are in part mediated by the Trithorax group (TrxG) complex and the Polycomb group (PcG) complex, which activate and repress transcription, respectively. We herein investigate the role of Menin, a component of the TrxG complex in T helper (Th) cell differentiation and show a critical role for Menin in differentiation and maintenance of Th17 cells. Menin(-/-) T cells do not efficiently differentiate into Th17 cells, leaving Th1 and Th2 cell differentiation intact in in vitro cultures. Menin deficiency resulted in the attenuation of Th17-induced airway inflammation. In differentiating Th17 cells, Menin directly bound to the Il17a gene locus and was required for the deposition of permissive histone modifications and recruitment of the RNA polymerase II transcriptional complex. Interestingly, although Menin bound to the Rorc locus, Menin was dispensable for the induction of Rorc expression and permissive histone modifications in differentiating Th17 cells. In contrast, Menin was required to maintain expression of Rorc in differentiated Th17 cells, indicating that Menin is essential to stabilize expression of the Rorc gene. Thus, Menin orchestrates Th17 cell differentiation and function by regulating both the induction and maintenance of target gene expression.

Stemness of T cells and the hematopoietic stem cells: fate, memory, niche, cytokines

Stem cells are able to generate both cells that differentiate and cells that remain undifferentiated but potentially have the same developmental program. The prolonged duration of the protective immune memory for infectious diseases such as polio, small pox, and measles, suggested that memory T cells may have stem cell properties. Understanding the molecular basis for the life-long persistence of memory T cells may be useful to project targeted therapies for immune deficiencies and infectious diseases and to formulate vaccines. In the last decade evidence from different laboratories shows that memory T cells may share self-renewal pathways with bone marrow hematopoietic stem cells. In stem cells the intrinsic self-renewal activity, which depends on gene expression, is known to be modulated by extrinsic signals from the environment that may be tissue specific. These extrinsic signals for stemness of memory T cells include cytokines such as IL-7 and IL-15 and there are other cytokine signals for maintaining the cytokine signature (TH1, TH2, etc.) of memory T cells. Intrinsic and extrinsic pathways that might be common to bone marrow hematopoietic stem cells and memory T lymphocytes are discussed and related to self-renewal functions.

Are microRNAs involved in the endocrine-specific pattern of tumorigenesis in multiple endocrine neoplasia type 1?

OBJECTIVE

To provide a general background regarding current knowledge about microRNA (miRNA) involvement in endocrine functions and in multiple endocrine neoplasia type 1 (MEN 1) endocrine tumorigenesis.

METHODS

A literature search was conducted in the miRNA database for articles on the role of miRNAs in the initiation and progression of human malignant conditions, inasmuch as miRNAs show different patterns of expression in normal and neoplastic tissues. We address the potential role of miRNAs in the endocrine pancreas, the pituitary gland, and the parathyroid glands-areas where MEN 1 shows high penetrance.

RESULTS

Experimental studies have shown the involvement of miRNAs in regulation of endocrine functions, such as insulin secretion. Moreover, studies have provided evidence that dysregulation of miRNAs was responsible for endocrine carcinogenesis, including pancreatic, pituitary, and parathyroid tumors.

CONCLUSION

miRNA expression profiles may become useful biomarkers for endocrine tumor diagnostics as well as potential targets of therapeutic strategies applied to pathologic conditions such as type 2 diabetes and endocrine tumors. Future studies should investigate the molecular and cellular mechanisms of tissue selectivity in MEN 1-associated tumorigenesis, in an effort to develop an RNA-based treatment that could prevent or delay the onset of MEN 1-associated tumors.

STAT6-mediated displacement of polycomb by trithorax complex establishes long-term maintenance of GATA3 expression in T helper type 2 cells

Polycomb group (PcG) and trithorax group (TrxG) complexes exert opposing effects on the maintenance of the transcriptional status of the developmentally regulated Hox genes. In this study, we show that activation of STAT6 induces displacement of the PcG complex by the TrxG complex at the upstream region of the gene encoding GATA3, a transcription factor essential for T helper type 2 (Th2) cell differentiation. Once Th2 cells differentiate, TrxG complex associated with the TrxG component Menin binds to the whole GATA3 gene locus, and this binding is required for the long-term maintenance of expression of GATA3 and Th2 cytokine. Thus, STAT6-mediated displacement of PcG by the TrxG complex establishes subsequent STAT6-independent maintenance of GATA3 expression in Th2 cells via the recruitment of the Menin-TrxG complex.

Insulinoma: pathophysiology, localization and management

Insulinoma is a rare neuroendocrine tumor that causes oversecretion of insulin and, as a result, patients present with symptoms of hypoglycemia. Fortunately, insulinomas are usually benign and solitary, and surgical cure rates are highly favorable. Most of these tumors occur sporadically, but they can also be associated with multiple endocrine neoplasia type-1 syndrome. The diagnosis is confirmed by a supervised fast, and early detection is important. Several preoperative and intraoperative techniques with various success rates have been employed in order to localize the lesion. When technically feasible, tumor enucleation is the procedure of choice; however, a more formal resection may be necessary for certain tumors. In the age of laparoscopy, the role of laparoscopic surgery in the management of insulinomas is continuing to attract attention. This review will discuss the historical background, pathogenesis, diagnosis, localization and management of insulinomas.

Recapitulation of pancreatic neuroendocrine tumors in human multiple endocrine neoplasia type I syndrome via Pdx1-directed inactivation of Men1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal syndrome caused by mutations in the MEN1 tumor suppressor gene. Whereas the protein product of MEN1, menin, is ubiquitously expressed, somatic loss of the remaining wild-type MEN1 allele results in tumors primarily in parathyroid, pituitary, and endocrine pancreas. To understand the endocrine specificity of the MEN1 syndrome, we evaluated biallelic loss of Men1 by inactivating Men1 in pancreatic progenitor cells using the Cre-lox system. Men1 deletion in progenitor cells that differentiate into exocrine and endocrine pancreas did not affect normal pancreas morphogenesis and development. However, mice having homozygous inactivation of the Men1 in pancreas developed endocrine tumors with no exocrine tumor manifestation, recapitulating phenotypes seen in the MEN1 patients. In the absence of menin, the endocrine pancreas showed increase in cell proliferation, vascularity, and abnormal vascular structures; such changes were lacking in exocrine pancreas. Further analysis revealed that these endocrine manifestations were associated with up-regulation in vascular endothelial growth factor expression in both human and mouse MEN1 pancreatic endocrine tumors. Together, these data suggest the presence of cell-specific factors for menin and a permissive endocrine environment for MEN1 tumorigenesis in endocrine pancreas. Based on our analysis, we propose that menin's ability to maintain cellular and microenvironment integrity might explain the endocrine- restrictive nature of the MEN1 syndrome.

An oncogenic role for the multiple endocrine neoplasia type 1 gene in prostate cancer

Prostate cancer is the second leading cause of cancer related deaths in US men, largely because of metastasis, which is ultimately fatal. A better understanding of metastasis biology will lead to improved prognostication and therapeutics. We previously reported 11q13.1 gain was independently predictive of recurrence after radical prostatectomy. Multiple endocrine neoplasia I (MEN1) maps to this region of copy number gain in aggressive prostate tumors and was shown to be the only gene at this locus at increased expression in prostate cancer. Here, we demonstrate an oncogenic role for MEN1 in prostate cancer using a variety of independent assays.

Multiple endocrine neoplasms

Multiple endocrine neoplasia type 1 (MEN1) and type 2 (MEN2) are rare autosomal-dominant disorders characterized by primary tumours in at least two different endocrine tissues. Both syndromes present as sporadic (a single case with two of the characteristic endocrine tumours) or familial form (an MEN case plus at least one first-degree relative showing one of the characteristic endocrine tumours). MEN1 is characterized by the occurrence of parathyroid, gastro-entero-pancreatic and anterior pituitary tumours, but it can include various combinations of more than 20 endocrine and non-endocrine tumours. Generally, tumours in MEN1 are benign, although gastrinomas and foregut carcinoids may exhibit a malignant course. MEN2 is characterized by medullary thyroid carcinoma (MTC), uni- or bi-lateral pheochromocytoma, and other tumours of different endocrine tissues. If not diagnosed precociously, MTC can be fatal. MEN1 develops after tissue inactivation of both MEN1 gene copies. Activating mutations of c-RET proto-oncogene causes MEN2.

Parathyroid tumor development involves deregulation of homeobox genes

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome caused by mutations in the MEN1 tumor suppressor gene. Loss of the functional second copy of the MEN1 gene causes individuals to develop multiple endocrine tumors, primarily affecting the parathyroid, pituitary, and pancreas. While it is clear that the protein encoded by MEN1, menin, suppresses endocrine tumors, its biochemical functions and direct downstream targets remain unclear. Recent studies have suggested that menin may act as a scaffold protein to coordinate gene transcription, and that menin is an oncogenic cofactor for homeobox (HOX) gene expression in hematopoietic cancer. The role of HOX genes in adult cell differentiation is still obscure, but growing evidence suggests that they may play important roles in the development of cancer. Therefore, we hypothesized that specific HOX genes were regulated by menin in parathyroid tumor development. Utilizing quantitative TaqMan RT-PCR, we compared expression profiles of the 39 HOX genes in human familial MEN1 (fMEN1) parathyroid tumors and sporadic parathyroid adenomas with normal samples. We identified a large set of 23 HOX genes whose deregulation is specific for fMEN1 parathyroid tumors, and only 5 HOX genes whose misexpression are specific for sporadic parathyroid tumor development. These findings provide the first evidence that loss of the MEN1 tumor suppressor gene is associated with deregulation of specific HOX gene expression in the development of familial human parathyroid tumors. Our results strongly reinforce the idea that abnormal expression of developmental HOX genes can be critical in human cancer progression.

MEN1 gene mutations in Hungarian patients with multiple endocrine neoplasia type 1

OBJECTIVE

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant hereditary disorder associated with mutations of the MEN1 gene. MEN1 may present as a familial or a sporadic disorder, with multiple endocrine tumours including parathyroid adenomas or hyperplasias, and pancreatic endocrine and pituitary gland tumours. The aim of this study was to examine the prevalence and spectrum of MEN1 gene mutations in Hungarian patients with familial and sporadic MEN1 and in those with a MEN1-related state.

DESIGN

Mutation analysis, using temporal temperature gradient gel electrophoresis and direct sequencing of all coding exons and the corresponding exon-intron boundaries of the MEN1 gene, was performed.

PATIENTS AND MEASUREMENTS

Peripheral blood DNA was obtained from 32 patients (19 index patients with familial or sporadic MEN1 and 13 index patients with familial or sporadic MEN1-related state). First degree relatives were also studied.

RESULTS

Ten different MEN1 gene mutations were identified in 10 index patients, including four novel mutations (A91V, G28A and E26X all in exon 2, and L301R in exon 6). All but one mutation occurred in index patients with familial or sporadic MEN1; the prevalence of mutation was considerably higher in index patients with familial MEN1 (6/6 patients, 100%) than in those with sporadic MEN1 (3/13 patients, 23%). Of the 13 index patients with a MEN1-related state, only one patient with recurrent isolated primary hyperparathyroidism had a MEN1 gene mutation. Family screening indicated mutations in six symptomatic and in one asymptomatic first degree relative.

CONCLUSION

These results confirm previous reports on the high prevalence of novel MEN1 gene mutations among patients with MEN1, and support the questionable efficacy of mutation screening in patients with sporadic MEN1-related states.

Age-related penetrance of endocrine tumours in multiple endocrine neoplasia type 1 (MEN1): a multicentre study of 258 gene carriers

OBJECTIVE

In multiple endocrine neoplasia type 1 (MEN1), age-related tumour penetrance according to the type of MEN1 germline mutation has not been investigated in-depth. This study was conducted to examine whether carriers of out-of-frame/truncating and in-frame MEN1 mutations differ in age-related tumour penetrance.

DESIGN

A multicentre study with biochemical, hormonal and radiological screening for MEN1-associated tumours.

PATIENTS

A total of 258 MEN1 carriers from six major German tertiary referral centres averaging 43 years of age at last follow-up.

MEASUREMENTS

Main outcome measure was time to first diagnosis of MEN1-associated tumours.

RESULTS

Independent of the year of birth and observation period, time to first tumour diagnosis did not vary much by the type of MEN1 germline mutation or endocrine organ system, and perhaps not even by the type of endocrine tumour when the amount of time was considered by which the diagnosis probably has been advanced through the manifestation of hormonal symptoms. Parathyroid hyperplasia and adenomas developed almost twice as often as enteropancreatic and pituitary tumours (77%vs. 49-32%), and more than five to sevenfold as often as adrenal cortical tumours and carcinoids (77%vs. 15-10%), reaching penetrance rates of up to 90%, 60%, 40%, 26% and 17%, respectively. The heterogeneity of tumour penetrance was marked, ranging from 9 years to 25 years for the earliest, and from 68 years to 77 years for the latest tumour manifestation.

CONCLUSIONS

Because of our inability of predicting tumour penetrance and malignant transformation individually, life-long follow-up of MEN1 carriers is warranted to prevent tumour morbidity.

Pituitary adenomas in childhood: development and diagnosis

Pituitary adenomas account for approximately 2.7% of all supratentorial tumors in the pediatric age range, and children are more likely than adults to develop a functioning adenoma. X chromosome inactivation studies indicate that pituitary adenomas arise from the clonal expression of a single mutated cell, and various intracellular mechanisms contribute to tumoral transformation. Functional pituitary tumors in childhood result in physical and biochemical effects of excess production of the oversecreted hormone, such as ACTH, prolactin, human growth hormone, TSH, LH, or FSH. In the clinical approach to pituitary adenomas, it is important to establish the presence of hormonal excess prior to undertaking imaging studies.

Menin and its interacting proteins: elucidation of menin function

The multiple endocrine neoplasia type 1 (MEN1) gene is a tumor suppressor gene encoding a 610 amino acid nuclear protein, menin. Although mutations of the MEN1 gene are responsible for MEN 1 syndrome, the intracellular functions of menin have not been fully elucidated. Recent data suggest that interactions between menin and menin-interacting proteins have a role in physiological regulation of cell growth, control of the cell cycle and genome stability, and are potentially important in bone development and multipotent mesenchymal stem cell differentiation. Loss of these interactions might also contribute to the development of MEN 1 syndrome.

Genetic screening methods for the detection of mutations responsible for multiple endocrine neoplasia type 1

Identification of mutations, which cause genetic diseases can be difficult when the disease is caused by the mutation of a large gene, which contains multiple exons. Detection of these mutations by DNA sequencing can be made more efficient by using mutation detection methods for pre-screening to identify the affected exon and to screen for the presence of already identified mutations in family members. These screening methods include denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE), single-strand conformation polymorphism, conformation-sensitive gel electrophoresis (CSGE), heteroduplex analysis and denaturing high-performance liquid chromatography (DHPLC). We discuss the advantages and shortcomings of these methods by reviewing the results of studies screening for mutations causing multiple endocrine neoplasia type 1 (MEN 1) syndrome, an autosomal dominant disorder characterized by endocrine tumours of the anterior pituitary gland, parathyroid glands, and pancreas. MEN 1 is caused by mutations of the MEN1 gene, a tumour suppressor gene, which contains one untranslated exon and nine exons. Previous studies have identified more than 400 germline and somatic mutations spreading across all the encoding sequence, and found no mutational "hot spot" or genotype-phenotype correlation. The wide diversity of mutations in the entire coding region of the MEN1 gene makes mutation screening time-consuming and expensive. We conclude that combination of mutation detection methods with DNA sequencing enhances the efficiency of identifying pathogenic mutations. However, it should be considered that experimental determination of the optimal electrophoresis conditions, such as using perpendicular electrophoresis to optimise DGGE or TGGE, is more useful than computerized algorithms to calculate these parameters.

Unusual presentation of multiple endocrine neoplasia type 1 in a young woman with a novel mutation of the MEN1 gene

We report an unusual presentation of multiple endocrine neoplasia type 1 (MEN 1) in a young woman who was subsequently proven to have a novel mutation of the MEN1 gene. The young patient, aged 25 years, was investigated for abdominal discomfort and left upper abdominal pain. Her family history was unremarkable, except an unknown disorder of her father causing early death. Abdominal ultrasonography (USG) and computed tomography revealed a giant pancreatic tumor measuring 10 cm in diameter. The diagnosis of a clinically nonfunctioning pancreatic neuroendocrine tumor was established by clinical and other studies, including USG-guided aspiration biopsy and octreotide scintigraphy, and the patient underwent a distal pancreatectomy. Histology proved a well-differentiated multinodular neuroendocrine tumor of the pancreas. During surgery, a subcutaneous lipoma was also removed from the abdominal wall. Two years later, the patient developed primary hyperparathyroidism, and two enlarged parathyroid glands were surgically removed. Magnetic resonance imaging of the pituitary gland was normal. Screening for MEN1 gene mutation by temperature gradient gel electrophoresis revealed heterozygosities in exons 3, 8, and 9, while direct sequencing indicated a novel germline mutation (C354X) resulting in a stop codon in exon 8 and polymorphisms in exon 3 (R171Q) and exon 9 (D418D and L432L). Genetic screening revealed no mutation in living family members. Our unusual case suggests that a multinodular pancreatic neuroendocrine tumor in a young patient may justify screening for MEN 1 syndrome, even in the absence of other endocrinopathy or family history.

The diffuse endocrine system: from embryogenesis to carcinogenesis

In the present review we will summarise the current knowledge about the cells comprising the Diffuse Endocrine System (DES) in mammalian organs. We will describe the morphological, histochemical and functional traits of these cells in three major systems gastrointestinal, respiratory and prostatic. We will also focus on some aspects of their ontogeny and differentiation, as well as to their relevance in carcinogenesis, especially in neuroendocrine tumors. The first chapter describes the characteristics of DES cells and some of their specific biological and biochemical traits. The second chapter deals with DES in the gastrointestinal organs, with special reference to the new data on the differentiation mechanisms that leads to the appearance of endocrine cells from an undifferentiated stem cell. The third chapter is devoted to DES of the respiratory system and some aspects of its biological role, both, during development and adulthood. Neuroendocrine hyperplasia and neuroendocrine lung tumors are also addressed. Finally, the last chapter deals with the prostatic DES, discussing its probable functional role and its relevance in hormone-resistant prostatic carcinomas.

Acromegaly and pheochromocytoma: report of a rare coexistence

OBJECTIVE

To describe a patient with the rare coexistence of acromegaly and pheochromocytoma.

METHODS

We report a case of a 57-year-old woman, who was initially examined because of polyarthritis, she was also diagnosed with type 2 diabetes mellitus and hypertension at age 56 years. Her history, clinical findings, laboratory results, and management are summarized, and etiologic hypotheses are discussed.

RESULTS

The patient had recurrent headaches and reported an increasing size of her shoes and gloves during the previous 4 years. Enlargement of her hands and feet and a bilateral temporal field defect were noted on examination. Laboratory studies revealed high levels of insulin-like growth factor I (IGF-I) and growth hormone (GH). Magnetic resonance imaging (MRI) showed a 3-cm sellar mass with impingement on the optic chiasm. The plasma level of growth hormone-releasing hormone (GHRH) was normal. She underwent transsphenoidal adenomectomy. Histologic examination confirmed a pituitary adenoma, immunoreactive for GH. Postoperatively, her headaches and arthritic pain diminished, and her levels of IGF-I and GH normalized; however, labile hypertension persisted. The urinary metanephrines and plasma catecholamines were increased. A 3-cm left adrenal mass, seen on abdominal MRI, was removed laparoscopically, after which urinary metanephrines normalized and both the diabetes and the hypertension resolved. Histopathologic analysis confirmed the diagnosis of pheochromocytoma. Immunohistochemical staining was negative for GHRH.

CONCLUSION

The finding of a pheochromocytoma and acromegaly could be a fortuitous coexistence of two separate endocrine tumors; however, the probability of such an event is extremely low. A cause-and-effect relationship has been suggested because of previous reports of GHRH production by pheochromocytomas. Some investigators have also suggested that this coexistence might be a multiple endocrine neoplasia variant. Our patient had no evidence of GHRH production, nor did we document any familial autosomal dominant transmission pattern.