Multiple Endocrine Neoplasia Type 1 Tumor Research Articles

A novel likely pathogenetic variant p.(Cys235Arg) of the MEN1 gene in multiple endocrine neoplasia type 1 with multifocal glucagonomas.

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary endocrine syndrome caused by pathogenic variants in MEN1 tumor suppressor gene. Diagnosis is commonly based on clinical criteria and confirmed by genetic testing. The objective of the present study was to report on a MEN1 case characterized by multiple pancreatic glucagonomas, with particular concern on the possible predisposing genetic defects. While conducting an extensive review of the most recent scientific evidence on the unusual glucagonoma familial forms, we analyzed the MEN1 gene in a 35-year-old female with MEN1, as well as her son and daughter, using Sanger and next-generation sequencing (NGS) approaches. We additionally explored the functional and structural consequences of the identified variant using in silico analyses. NGS did not show any known pathogenic variant in the tested regions. However, a new non-conservative variant in exon 4 of MEN1 gene was found in heterozygosity in the patient and in her daughter, resulting in an amino acid substitution from hydrophobic cysteine to hydrophilic arginine at c.703T > C, p.(Cys235Arg). This variant is absent from populations databases and was never reported in full papers: its characteristics, together with the high specificity of the patient's clinical phenotype, pointed toward a possible causative role. Our findings confirm the need for careful genetic analysis of patients with MEN1 and establish a likely pathogenic role for the new p.(Cys235Arg) variant, at least in the rare subset of MEN1 associated with glucagonomas.

Abstract #1412022: A Rare Case of Multiple Endocrine Neoplasia Type 1 (MEN1) Presenting with Recurrent Abdominal Pain

MEN1 is a rare genetic disorder characterized by combined occurrence of two or more tumors involving parathyroid, anterior pituitary and the neuroendocrine tissue of gastro-entero-pancreatic organ system. We present a case of a young male with recurrent abdominal pain who was later diagnosed with MEN1 syndrome. 27-year-old male with past medical history of chronic abdominal pain presented for an episode of acute upper abdominal pain which was constant and worsened with any movement or palpation. His family history was significant for father having parathyroid disorder and skin lesions. On examination, he was ill appearing with tachycardia, multiple skin lesions and tenderness in upper abdomen. Labs were significant for leukocytosis and hypercalcemia (corrected level 10.5 mg/dl). Rest of the electrolytes, kidney function, liver enzymes and lipase were normal. Computed tomography (CT) abdomen showed inflammatory changes and thickening along the distal stomach/proximal duodenum with scattered free air, concerning for a perforated ulcer. Indeterminate bilateral adrenal nodules were also noted. Patient underwent emergent exploratory laparotomy and was noted to have small perforation in the anterior proximal portion of the duodenum which was repaired. Post-operatively, work up for persistent hypercalcemia revealed parathyroid hormone levels of 152 pg/ml and 25-hydroxy vitamin D of 13.7 ng/ml. He was diagnosed with primary hyperparathyroidism and upon stabilization, discharged with plan for outpatient follow-up. After few months, he had another admission due to worsening epigastric pain. Repeat CT abdomen showed multiple pancreatic lesions involving head, tail and uncinate process and stable adrenal nodules. Presence of pancreatic lesions, gastric ulcers, hyperparathyroidism, adrenal nodules, and multiple skin lesions raised concern of MEN1. Further evaluation showed elevated gastrin level (633 pg/ml), chromogranin level (2464 ng/mL) and mildly elevated prolactin. Rest of pituitary and adrenal axis hormone levels were normal. MEN1 gene testing was positive. No pituitary lesion was identified on magnetic resonance imaging brain. He underwent subtotal parathyroidectomy and cervical thymectomy. He was continued on twice daily pantoprazole and was discharged home in stable condition. MEN1 tumor types and age of tumor onset can differ significantly, and tumors become evident either by hormonal overproduction or by tumor growth. There are no genotype phenotype correlations, even within the same family. Pharmacological therapies to suppress hypersecretion are often first line and can be successful in up to 50% patients. Surgery is an option for patients with hypersecretion unresponsive to medical therapy, compression of the optic nerves and/or chiasma endangering vision or when there is uncertainty of diagnosis requiring biopsy. MEN1 is linked with higher mortality. Approximately 70% of the MEN1 deaths are due to thymic neuroendocrine tumors (NETs) and duodenopancreatic-NETs. Early diagnosis of tumors with appropriate interventions can significantly improve patient survival.

Approach of Multiple Endocrine Neoplasia Type 1 (MEN1) Syndrome-Related Skin Tumors.

Non-endocrine findings in patients with MEN1 (multiple endocrine neoplasia) syndrome also include skin lesions, especially tumor-type lesions. This is a narrative review of the English-language medical literature including original studies concerning MEN1 and dermatological issues (apart from dermatologic features of each endocrine tumor/neuroendocrine neoplasia), identified through a PubMed-based search (based on clinical relevance, with no timeline restriction or concern regarding the level of statistical significance). We identified 27 original studies involving clinical presentation of patients with MEN1 and cutaneous tumors; eight other original studies that also included the genetic background; and four additional original studies were included. The largest cohorts were from studies in Italy (N = 145 individuals), Spain (N = 90), the United States (N = 48 and N = 32), and Japan (N = 28). The age of patients varied from 18 to 76 years, with the majority of individuals in their forties. The most common cutaneous tumors are angiofibromas (AF), collagenomas (CG), and lipomas (L). Other lesions are atypical nevi, basocellular carcinoma, squamous cell carcinoma, acrochordons, papillomatosis confluens et reticularis, gingival papules, and cutaneous T-cell lymphoma of the eyelid. Non-tumor aspects are confetti-like hypopigmentation, café-au-lait macules, and gingival papules. MEN1 gene, respective menin involvement has also been found in melanomas, but the association with MEN1 remains debatable. Typically, cutaneous tumors (AF, CG, and L) are benign and are surgically treated only for cosmetic reasons. Some of them are reported as first presentation. Even though skin lesions are not pathognomonic, recognizing them plays an important role in early identification of MEN1 patients. Whether a subgroup of MEN1 subjects is prone to developing these types of cutaneous lesions and how they influence MEN1 evolution is still an open issue.

Comparison Between Sporadic and Multiple Endocrine Neoplasia Type 1-Associated Insulinoma.

The differences between sporadic and multiple endocrine neoplasia type 1 (MEN-1)-associated insulinoma are not well described. Herein, we compared demographics, neoplasm characteristics, presentation, and survival in patients with sporadic vs MEN-1 insulinomas including benign and malignant disease. A retrospective study identified insulinoma patients. MEN-1 was defined based on genetic testing or clinically in patients with 2 or more primary MEN-1 tumor types. A total of 311 patients were identified: 84% benign and 16% malignant. The incidence of malignancy was similar (18% vs 16%, MEN-1 vs sporadic, p = 0.76). Within malignant patients, the median (interquartile range) age was 33 (25 ,44) years in MEN-1 vs 54 (41, 70) years in sporadic insulinoma (p = 0.04). There was no difference in sex or tumor size between MEN-1 and sporadic malignant insulinoma (p > 0.05). Of the 260 patients with benign insulinoma, 7% had MEN-1 syndrome. MEN-1 patients presented with insulinoma at a younger age: median (interquartile range) age was 38 (24, 49) years vs 52 (43, 65) years (p < 0.01). Resection of benign insulinoma was performed in 78% of the MEN-1 and 94% of the sporadic group (p = 0.03). Resected benign tumors were larger in the MEN-1 group: 2.0 (1.65, 2.45) cm vs 1.5 (1.2, 2.0) cm, respectively (p = 0.03). Concurrent insulinomas were more common in MEN-1 (17% vs 2%; p < 0.01). MEN-1 patients present with insulinoma at younger age and have larger benign pancreatic lesions at the time of resection compared with sporadic neoplasms. Younger patients and those with multifocal pancreatic neuroendocrine tumor in the setting of endogenous hyperinsulinism should be evaluated for MEN-1.

Multi-omics analyses of MEN1 missense mutations identify disruption of menin–MLL and menin–JunD interactions as critical requirements for molecular pathogenicity

BackgroundLoss-of-function mutations of the multiple endocrine neoplasia type 1 (MEN1) gene are causal to the MEN1 tumor syndrome, but they are also commonly found in sporadic pancreatic neuroendocrine tumors and other types of cancers. The MEN1 gene product, menin, is involved in transcriptional and chromatin regulation, most prominently as an integral component of KMT2A/MLL1 and KMT2B/MLL2 containing COMPASS-like histone H3K4 methyltransferase complexes. In a mutually exclusive fashion, menin also interacts with the JunD subunit of the AP-1 and ATF/CREB transcription factors.ResultsHere, we applied and in silico screening approach for 253 disease-related MEN1 missense mutations in order to select a set of nine menin mutations in surface-exposed residues. The protein interactomes of these mutants were assessed by quantitative mass spectrometry, which indicated that seven of the nine mutants disrupt interactions with both MLL1/MLL2 and JunD complexes. Interestingly, we identified three missense mutations, R52G, E255K and E359K, which predominantly reduce the MLL1 and MLL2 interactions when compared with JunD. This observation was supported by a pronounced loss of binding of the R52G, E255K and E359K mutant proteins at unique MLL1 genomic binding sites with less effect on unique JunD sites.ConclusionsOur results underline the effects of MEN1 gene mutations in both familial and sporadic tumors of endocrine origin on the interactions of menin with the MLL1 and MLL2 histone H3K4 methyltransferase complexes and with JunD-containing transcription factors. Menin binding pocket mutants R52G, E255K and E359K have differential effects on MLL1/MLL2 and JunD interactions, which translate into differential genomic binding patterns. Our findings encourage future studies addressing the pathophysiological relevance of the separate MLL1/MLL2- and JunD-dependent functions of menin mutants in MEN1 disease model systems.

Bone phenotypes in multiple endocrine neoplasia type 1: survey on the MEN1 Florentine database.

Multiple endocrine neoplasia type 1 (MEN1) is a rare, inherited cancer syndrome characterized by the development of multiple endocrine and non-endocrine tumors. MEN1 patients show a reduction of bone mass and a higher prevalence of early onset osteoporosis, compared to healthy population of the same age, gender, and ethnicity. During the monitoring and follow-up of MEN1 patients, the attention of clinicians is primarily focused on the diagnosis and therapy of tumors, while the assessment of bone health and mineral metabolism is, in many cases, marginally considered. In this study, we retrospectively analyzed bone and mineral metabolism features in a series of MEN1 patients from the MEN1 Florentine database. Biochemical markers of bone and mineral metabolism and densitometric parameters of bone mass were retrieved from the database and were analyzed based on age ranges and genders of patients and presence/absence of the three main MEN1-related endocrine tumor types. Our evaluation confirmed that patients with a MEN1 diagnosis have a high prevalence of earlyonset osteopenia and osteoporosis, in association with levels of serum and urinary markers of bone turnover higher than the normal reference values, regardless of their different MEN1 tumors. Fifty percent of patients younger than 26 years manifested osteopenia and 8.3% had osteoporosis, in at least one of the measured bone sites. These data suggest the importance of including biochemical and instrumental monitoring of bone metabolism and bone mass in the routine medical evaluation and follow-up of MEN1 patients and MEN1 carriers as important clinical aspects in the management of the syndrome.

Role of miR-24 in Multiple Endocrine Neoplasia Type 1: A Potential Target for Molecular Therapy.

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited multiple cancer syndrome of neuroendocrine tissues. Tumors are caused by an inherited germinal heterozygote inactivating mutation of the MEN1 tumor suppressor gene, followed by a somatic loss of heterozygosity (LOH) of the MEN1 gene in target neuroendocrine cells, mainly at parathyroids, pancreas islets, and anterior pituitary. Over 1500 different germline and somatic mutations of the MEN1 gene have been identified, but the syndrome is completely missing a direct genotype-phenotype correlation, thus supporting the hypothesis that exogenous and endogenous factors, other than MEN1 specific mutation, are involved in MEN1 tumorigenesis and definition of individual clinical phenotype. Epigenetic factors, such as microRNAs (miRNAs), are strongly suspected to have a role in MEN1 tumor initiation and development. Recently, a direct autoregulatory network between miR-24, MEN1 mRNA, and menin was demonstrated in parathyroids and endocrine pancreas, showing a miR-24-induced silencing of menin expression that could have a key role in initiation of tumors in MEN1-target neuroendocrine cells. Here, we review the current knowledge on the post-transcriptional regulation of MEN1 and menin expression by miR-24, and its possible direct role in MEN1 syndrome, describing the possibility and the potential approaches to target and silence this miRNA, to permit the correct expression of the wild type menin, and thereby prevent the development of cancers in the target tissues.

Comprehensive Analysis of Clinical Features in Index Cases With Multiple Endocrine Neoplasia Type 1 Refine the Risk Rate for Detection of Mutation Distinguishing Negative-Mutation (Phenocopies) and Positive-Mutation Cases

Background: Index cases clinically diagnosed with multiple endocrine neoplasia type 1 (MEN1) are declared as MEN1 phenocopies if no germline MEN1 mutation is identified. In comparison with positive-mutation cases, most phenocopies have been diagnosed in older age, mainly by association of primary hyperparathyroidism (HPT) and pituitary adenoma (PIT), with HPT predominantly diagnosed as uniglandular disease. Besides that, phenocopies rarely develop a third MEN1-related tumor and are associated with lower morbidity and longer survival. However, all these data are mainly derived of genetic studies by Sanger targeted to MEN1 gene from a strict number of MEN1 phenocopies. Objectives: to recognize strong clinical profiles capable of predicting the occurrence or absence of germline MEN1 mutation refining the clinical differentiation of phenocopies and mutation-positive cases before genetic testing disclosure. Casuistic/Methods: 143 MEN1 index cases: 87 MEN1-positive and 56 true MEN1 phenocopies (excluded mutations for MLPA assay and by a mini-painel based on long-range PCR and next generation sequencing of 6 MEN1-related genes (MEN1, p15, p18, p21, p27, AIP) covering full coding and non-coding regions. Results: High detectability rate of MEN1 mutation was associated with the presence of ≥ 4 organs affected for primary tumors (100%), association of HPT/PET (neuroendocrine pancreatic tumor)/PIT (93%), HPT/PET (81%), positive familial history (88% vs. 48%), presence of PET (84%) as malign (80%) as multifocal (95%), two different PETs (100%), multiglandular HPT (81%) and diagnosis of one MEN1-related tumor (93%) or of two/three MEN1 tumors diagnosed before 21y (100%). The combination HPT/PIT has the lowest rate of detection of mutation (33%), it is even lower if PIT was acromegaly (12%) or age at the diagnosis of HPT and PIT was, respectively, > 45y and >30y (8%) and absent if it is added uniglandular HPT (0%) or if there was association HPT/PIT (age-independent) with uniglandular HPT (0%). The prediction for detection of mutation increases if these HPT (> 45y)/PIT (> 30y) cases have multiglandular HPT (20%) and it is 100% with association HPT (< 30y)/PIT (< 21y). A p <0.05 was observed to all data above. Conclusions: By integration of phenotypic clues and full genetic analysis applied to the largest MEN1 phenocopy series, we identified strong clinical predictors capable of anticipate the potential risk rate for mutation detection revealing the estimated chance of an index case harbor a mutation or be classified as phenocopy. By their peculiarities, the management/treatment of phenocopies should potentially be different of that recommended to mutation-positive cases.

Comparative Analysis of Different International Criteria (ACMG-AMP vs. TENGEN) Applied to Classification of Missense Germline Allelic Variants in Patients With Multiple Endocrine Neoplasia Type 1 or Suspected to this Syndrome

Context: Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant genetic syndrome caused by germline pathogenic allele variants (PAV) in the MEN1 tumor suppressor gene, which predispose MEN1 carriers to the increased risk of several endocrine neoplasms throughout life. The MEN1 gene (11q13), contains 10 exons encoding the MENIN protein. About 600 different PAVs have been reported, with 25% of them being missense variants. Of value, the definition of pathogenicity can be challenging, especially for missense variants. Thus, international guidelines for improving the classification of allele variants were recently defined by the ACMG-AMP (2015). Recently, applying ACMG-AMP criteria with inclusion of clinical features the TENGEN French group suggested modifications aiming to refine the classification of variants in MEN1 syndrome. Objective: To classify missense allelic variants found in the MEN1 gene by the ACMG-AMP guideline using VARSOME and by the TENGEN group to support a comparative analysis of the results obtained with these two methodologies (ACMG-AMP; TENGEN). Methods: the classification of 16 different missense allele variants identified in 17 index cases with or suspected to MEN1 syndrome was conducted according to ACMG-AMP criteria using the VARSOME software followed by the analysis defined by the TENGEN group. Results: Of the 16 variants, 6 were new, 1 was recurrent (2 unrelated index cases) and 9 of them occurred in codons with previous reports of different amino acid exchanges in the same region. Differences observed in the classification by ACMG-AMP and TENGEN were: pathogenic variant (6% vs. 65%); probably pathogenic (88% vs. 12%) and variants of uncertain significance (VUS) (6% vs. 23%). The four VUS classified by TENGEN (one of them for ACMG-AMP) were of sporadic cases without clinical diagnosis of MEN1 (2, for one MEN1-related tumor in early age; 1, for suspected MEN1) or with high risk of phenocopy (1, HPT + acromegaly). Conclusion: The difference observed in the classification of the pathogenicity of these variants, especially due to the higher occurrence of VUS in TENGEN, indicates that the criteria adopted by ACMG-VARSOME would have to be refined for clinical features. By other side, TENGEN apparently reinforce the classification of pathogenicity in cases with clinical diagnosis of MEN1 and reduce the definition of pathogenicity to variants found in MEN1-suspected cases without clinical criteria for the MEN1 diagnosis. These protocols apparently need to be investigate, validated and, probably, improved in other cohorts to reduce risks of misinterpretations and classifications that can, lately, interfere in genetic counseling and in the clinical management of patients. Finally, long-term outcome of cases classified as VUS, functional studies and, familial segregation may reinforce the initial impressions obtained with TENGEN classification.

A Rare Presentation of Multiple Endocrine Neoplasia Type 1

Background: Multiple endocrine neoplasia type 1 (MEN1) is a rare, autosomal dominant inherited syndrome caused by mutations in the MEN1 tumor suppressor gene with a reported incidence of 2 in 100,000.Clinical Case: A 26-year-old Caucasian female was seen for surveillance screening given positive familial mutation in the MEN1 gene. She had a significant family history of pathogenic MEN1 in her son, brother, father and paternal aunt. On presentation, she denied any history of headache, nipple discharge, kidney stones, fractures, heart burn, abdominal pain, diarrhea, hypoglycemia, flushing, lightheadedness. She was on hormonal IUD for contraception and had not had menstrual cycles for the last 6 months. Vital signs and physical examination were unremarkable. Her initial evaluation included a normal calcium of 9.8mg/dL (RR:8.6-10.6mg/dL), PTH of 70pg/ml (RR:12-88pg/ml), 25OH-vitamin-D of 11ng/ml (RR:20-80ng/ml). She had normal gastrin, chromogranin A, glucagon, and vasoactive intestinal peptide levels. Prolactin was 17.6ng/ml (RR:3.3-26.7 ng/ml). MRI pituitary showed a 6mm lesion representing a Rathke’s cleft cyst, not compressing surrounding structures.Two months following the initial encounter, she presented with abdominal pain, nausea, vomiting. She was found to have an obstructing renal stone requiring stent placement. Calcium was 10.1mg/dl. She was also noted to have an incidental pancreatic tail mass of 4.2cm on CT abdomen. She underwent laparoscopic robotic distal spleno-pancreatectomy. Surgical pathology showed a well differentiated 3.5cm neuroendocrine tumor with negative margins, which stained positively for insulin. She had not reported symptoms of weight gain or any episodes suspicious for sympathoadrenal activation or neuroglycopenia, and was again confirmed after surgery.Patient was re-admitted to the hospital for right-sided flank pain and was found to have a new 6mm obstructing calculus with moderate hydronephrosis of the right kidney. Corrected calcium level was found to be mildly elevated at 11.1mg/dL. Repeat PTH was stable at 81pg/ml, and urinary calcium was elevated at 447.3mg/24h (RR:50-250mg/24h). Subsequently, she underwent 3.5 gland parathyroidectomy and thymectomy. On POD20, PTH was 29pg/ml and calcium was 8.6mg/dl.Conclusion: This case highlights a rare presentation of MEN1 with an asymptomatic insulinoma and nephrolithiasis, despite having normal calcium and PTH levels initially. Primary hyperparathyroidism is the most common presentation of MEN1, seen in up to 90% of patients. The second most common finding in MEN1 patients, reported in 70% of the cases, are entero-pancreatic tumors, the most common being gastrinoma. Insulinoma, which is less common and is seen in only 10-30% patients, needs documentation of Whipple’s triad. Interestingly, our patient never had any history of hypoglycemia.

Genomic profiling of multiple tissues in two patients with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant tumor syndrome. This hereditary cancer is caused by germline variants in MEN1. Two patients with MEN1 were identified via whole exome sequencing and gene expression profile analysis, conducted for 5,063 patients with various types of cancers. We obtained multiple tumors from each patient; tumors derived from these two MEN1 patients had a loss of the normal MEN1 allele and frequently chromosomal copy number changes. Thus, we investigated whether structural variants were present in the MEN1 patient genomes. Whole-genome sequencing revealed no catastrophic rearrangements, and the tumor samples had very low somatic variants. The two patients had germline variants in MEN1 and some chromosomal copy number changes including on chromosome 11. The only pathogenic variant detected was the MEN1 germline variant, and chromosomal rearrangements led to tumorigenesis in somatic cells. Furthermore, the MEN1 tumor samples displayed a specific signature characterized by T:A>C:G transition. Studies of multiple tumors obtained from single patients are rare in hereditary cancer syndromes, and our results provide insights that the second hit of the tumor suppressor gene MEN1 may be caused by a gross genome rearrangement, not a small insertion and deletion, nor a change in epigenetic regulation.

Phenotypes Associated With MEN1 Syndrome: A Focus on Genotype-Phenotype Correlations.

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited tumor syndrome, associated with parathyroid, pituitary, and gastro-entero-pancreatic (GEP) neuroendocrine tumors (NETs). MEN1 is usually consequent to different germline and somatic mutations of the MEN1 tumor suppressor gene, although phenocopies have also been reported. This review analyzed main biomedical databases searching for reports on MEN1 gene mutations and focused on aggressive and aberrant clinical manifestations to investigate the potential genotype-phenotype correlation. Despite efforts made by several groups, this link remains elusive to date and evidence that aggressive or aberrant clinical phenotypes may be related to specific mutations has been provided by case reports and small groups of MEN1 patients or families. In such context, a higher risk of aggressive tumor phenotypes has been described in relation to frameshift and non-sense mutations, and predominantly associated with aggressive GEP NETs, particularly pancreatic NETs. In our experience a novel heterozygous missense mutation at c.836C>A in exon 6 was noticed in a MEN1 patient operated for macro-prolactinoma, who progressively developed recurrent parathyroid adenomas, expanding gastrinomas and, long after the first MEN1 manifestation, a neuroendocrine uterine carcinoma. In conclusion, proof of genotype-phenotype correlation is limited but current evidence hints at the need for long-term interdisciplinary surveillance in patients with aggressive phenotypes and genetically confirmed MEN1.

Multiple Endocrine Neoplasia Type 1: The Potential Role of microRNAs in the Management of the Syndrome.

Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited tumor syndrome, characterized by the development of multiple neuroendocrine tumors (NETs) in a single patient. Major manifestations include primary hyperparathyroidism, gastro-entero-pancreatic neuroendocrine tumors, and pituitary adenomas. In addition to these main NETs, various combinations of more than 20 endocrine and non-endocrine tumors have been described in MEN1 patients. Despite advances in diagnostic techniques and treatment options, which are generally similar to those of sporadic tumors, patients with MEN1 have a poor life expectancy, and the need for targeted therapies is strongly felt. MEN1 is caused by germline heterozygous inactivating mutations of the MEN1 gene, which encodes menin, a tumor suppressor protein. The lack of a direct genotype–phenotype correlation does not permit the determination of the exact clinical course of the syndrome. One of the possible causes of this lack of association could be ascribed to epigenetic factors, including microRNAs (miRNAs), single-stranded non-coding small RNAs that negatively regulate post-transcriptional gene expression. Some miRNAs, and their deregulation, have been associated with MEN1 tumorigenesis. Recently, an extracellular class of miRNAs has also been identified (c-miRNAs); variations in their levels showed association with various human diseases, including tumors. The aim of this review is to provide a general overview on the involvement of miRNAs in MEN1 tumor development, to be used as possible targets for novel molecular therapies. The potential role of c-miRNAs as future non-invasive diagnostic and prognostic biomarkers of MEN1 will be discussed as well.

Multiple Endocrine Neoplasia Type 1 (MEN1) 5'UTR Deletion, in MEN1 Family, Decreases Menin Expression.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the occurrence of parathyroid, pancreatic and pituitary tumors, and is due to mutations in the coding region of the MEN1 gene, which encodes menin. We investigated a family with identical twins that had MEN1, with different MEN1 tumors. DNA sequence analysis of the MEN1 coding region had not identified any abnormalities and we hypothesized that deletions and mutations involving the untranslated regions may be involved. Informed consent and venous blood samples were obtained from five family members. Sanger DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) analyses were performed using leukocyte DNA. This revealed a heterozygous 596bp deletion (Δ596bp) between nucleotides -1087 and -492 upstream of the translation start site, located within the MEN1 5' untranslated region (UTR), and includes the core promoter and multiple cis-regulatory regions. To investigate the effects of this 5'UTR deletion on MEN1 promoter activity, we generated luciferase reporter constructs, containing either wild-type 842bp or mutant 246bp MEN1 promoter, and transfected them into human embryonic kidney HEK293 and pancreatic neuroendocrine tumor BON-1 cells. This revealed the Δ596bp mutation to result in significant reductions by 37-fold (p < 0.0001) and 16-fold (p < 0.0001) in luciferase expression in HEK293 and BON-1 cells, respectively, compared to wild-type. The effects of this 5'UTR deletion on MEN1 transcription and translation were assessed using qRT-PCR and Western blot analyses, respectively, of mRNA and protein lysates obtained from Epstein-Barr-virus transformed lymphoblastoid cells derived from affected and unaffected individuals. This demonstrated the Δ596bp mutation to result in significant reductions of 84% (p < 0.05) and 88% (p < 0.05) in MEN1 mRNA and menin protein, respectively, compared to unaffected individuals. Thus, our results report the first germline MEN1 5'UTR mutation and highlight the importance of investigating UTRs in MEN1 patients who do not have coding region mutations. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Prognostic factors for the outcome of nonfunctioning pancreatic neuroendocrine tumors in MEN1: a systematic review of literature.

Metastatic duodenopancreatic neuro-endocrine tumors (dpNETs) are the most important disease-related cause of death in patients with multiple endocrine neoplasia type 1 (MEN1). Nonfunctioning pNETs (NF-pNETs) are highly prevalent in MEN1 and clinically heterogeneous. Therefore, management is controversial. Data on prognostic factors for risk stratification are limited. This systematic review aims to establish the current state of evidence regarding prognostic factors in MEN1-related NF-pNETs. We systematically searched four databases for studies assessing prognostic value of any factor on NF-pNET progression, development of distant metastases, and/or overall survival. In- and exclusion, critical appraisal and data-extraction were performed independently by two authors according to pre-defined criteria. Thirteen studies (370 unique patients) were included. Prognostic factors investigated were tumor size, timing of surgical resection, WHO grade, methylation, p27/p18 expression by immunohistochemistry (IHC), ARX/PDX1 IHC and alternative lengthening of telomeres. Results were complemented with evidence from studies in MEN1-related pNET for which data could not be separately extracted for NF-pNET and data from sporadic NF-pNET. We found that the most important prognostic factors used in clinical decision making in MEN1-related NF-pNETs are tumor size and grade. NF-pNETs <2 cm may be managed with watchful waiting, while surgical resection is advised for NF-pNETs ≥2 cm. Grade 2 NF-pNETs should be considered high risk. The most promising and MEN1-relevant avenues of prognostic research are multi-analyte circulating biomarkers, tissue-based molecular factors and imaging-based prognostication. Multi-institutional collaboration between clinical, translation and basic scientists with uniform data and biospecimen collection in prospective cohorts should advance the field.

Multiple Endocrine Neoplasia Type 1 (MEN1): An Update and the Significance of Early Genetic and Clinical Diagnosis.

Multiple endocrine neoplasia type 1 (MEN1) is a rare hereditary tumor syndrome inherited in an autosomal dominant manner and characterized by a predisposition to a multitude of endocrine neoplasms primarily of parathyroid, enteropancreatic, and anterior pituitary origin, as well as nonendocrine neoplasms. Other endocrine tumors in MEN1 include foregut carcinoid tumors, adrenocortical tumors, and rarely pheochromocytoma. Nonendocrine manifestations include meningiomas and ependymomas, lipomas, angiofibromas, collagenomas, and leiomyomas. MEN1 is caused by inactivating mutations of the tumor suppressor gene MEN1 which encodes the protein menin. This syndrome can affect all age groups, with 17% of patients developing MEN1-associated tumors before 21 years of age. Despite advances in the diagnosis and treatment of MEN1-associated tumors, patients with MEN1 continue to have decreased life expectancy primarily due to malignant neuroendocrine tumors. The most recent clinical practice guidelines for MEN1, published in 2012, highlight the need for early genetic and clinical diagnosis of MEN1 and recommend an intensive surveillance approach for both patients with this syndrome and asymptomatic carriers starting at the age of 5 years with the goal of timely detection and management of MEN1-associated neoplasms and ultimately decreased disease-specific morbidity and mortality. Unfortunately, there is no clear genotype-phenotype correlation and individual mutation-dependent surveillance is not possible currently.

SUN-046 Identification of Clinical Predictors for Detection of Mutations in Multiple Endocrine Neoplasia Type 1

Context: Guidelines has systematically suggested genetic testing for a wide spectrum of phenotypes in order to confirm or exclude surely the diagnosis of multiple endocrine neoplasia type 1 (MEN1). However, the probability of find a germline MEN1 mutation has showed extremely variable (5-95%) when different phenotypes are considered. The prompt recognition of potential clinical predictors could anticipate the result of the genetic testing in the different clinical scenarios. Objective: To investigate if specific phenotypic features may predict the presence of germline MEN1 mutations in index-cases with clinical diagnosis of MEN1 syndrome. Methods and Patients: 110 MEN1 index cases were included: amplicons based on long-range PCR covering the full MEN1 open reading frame of 94 MEN1 index cases (49 familial, 45 sporadic) were sequenced by targeted-Next Generation Sequencing (tNGS) MiSeq Illumina platform while Sanger Sequencing (SS) was approached to the other 16 MEN1 index cases (2 familial, 14 sporadic). MLPA assay was supported to 31 MEN1-negative patients by tNGS/SS whose DNA samples were available. Results: 68 index cases (62%) had germline MEN1 mutations. With the tNGS/SS/MLPA protocol, the mutation detectability rate was higher in familial MEN1 (90%, 46/51 vs. 37%; 22/59; p, < 0.05). In comparison with MEN1-positive patients, MEN1-negative cases were older (53±12 vs. 39±13; p, < 0.05) and most of them had no more than two MEN1-related tumors (76%, 32/42 vs. 10%, 7/68; p, < 0.05). Considering the subset of 59 patients with negative familial history, the 22 MEN1-positive patients revealed clinical predictors for detection of MEN1 mutation when they were compared with 37 truly non-MEN1 mutation carriers. Thus, sporadic MEN1-positive patients had higher significantly prevalence of the following predictors. 1) ≥ 3 tumors, 86% (19/22) versus 11% (4/37); 2) PETs, 86% (19/22) versus 22% (8/37); 3) which were multifocal, 100% versus 1/8 (9%); 4) with frequent synchronic association of functioning and NF/PETs, 47% (9/19) versus 0% and; 5) high frequency of malignancies, 58% (11/19) versus 5% (2/37). Indeed, there was confirmation of these predictors comparing all 68 MEN1-positive carriers against 42 MEN1-negative cases. Conclusions: The strategy adopted to support the diagnosis of MEN1 based on analysis of clinical predictors and genetic testing for tNGS/SS-MLPA underscored that the positive familial history, occurrence of three or more MEN1 tumors, presence of PETs, especially multifocal PETs, and malignancies are strong predictors to detection of MEN1 mutations.

SAT-310 18F-FDOPA PET/CT Accurately Identifies Pheochromocytoma in 70-Year-Old Male with MEN1

18F-FDOPA PET/CT accurately identifies pheochromocytoma in 70-year-old male with MEN1 Background: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant inherited disorder that causes tumors most often in the parathyroid, pancreas, and pituitary. Pheochromocytoma in MEN1 is extremely rare (< 2% of cases). Identifying tumor functionality by imaging is challenging given the multiplicity of tumors in MEN1. Case Report: We are reporting a case of a 75-year old male first diagnosed at age 60 with MEN1. Sequencing of MEN1 revealed the pathogenic variant c.249_252delGTCT causing a frameshift mutation. At the time of diagnosis, he was found to have mild hyperparathyroidism status post 2-gland resection, non-functional pituitary microadenoma and bilateral adrenal masses (2.6 cm left; 2.4 cm right). The patient was normotensive and asymptomatic, with elevated plasma normetanephrine 114 pg/mL (upper limit of normal 112) and metanephrine 148 pg/mL (upper limit of normal 61). The remainder of his biochemical workup at that time was normal. The patient remained normotensive and asymptomatic, and routine yearly CT evaluation demonstrated growth of the left adrenal mass to 3.9 cm (9 Hounsfield unit (HU) pre-contrast, and post-contrast HU of 15), and right adrenal mass to 2.6 cm. Follow-up biochemical evaluation revealed an adrenergic biochemical phenotype with elevated plasma metanephrine 432 (12-61 pg/ml) and normetanephrine 291 (18-112 pg/ml) levels, with normal norepinephrine 198 (84-794 pg/ml), dopamine <25 (0-25 pg/ml) but elevated epinephrine 126 (0-57 pg/ml) levels. FDG-PET/CT demonstrated bilateral adrenal uptake (6.36 SUV on the left, and 4.38 SUV on the right) and I-123-MIBG scintigraphy demonstrated abnormal uptake of tracer corresponding to both adrenal masses. However, 18F-FDOPA PET/CT demonstrated a centrally photopenic left adrenal mass (28.7 SUV) and physiologic 18F-FDOPA PET uptake on the right adrenal mass. 68Ga-DOTATATE was not available at the time. The patient underwent an uneventful left adrenalectomy for pheochromocytoma in June 2016 and has had normalization of his previously elevated biochemical results. Loss of heterozygosity at 11q13 was analyzed and determined to be positive. Conclusion: Pheochromocytoma in MEN1 is extremely rare. Despite a lack of symptoms, enlarging adrenal nodules should be screened for pheochromocytoma. Particularly in the setting of elevated plasma metanephrines and undetermined adrenal masses by anatomic imaging, FDG-PET/CT and/or I-123-MIBG, 18F-FDOPA PET/CT may be beneficial.

When Parathyroidectomy Should Be Indicated or Postponed in Adolescents With MEN1-Related Primary Hyperparathyroidism.

Multiple Endocrine Neoplasia Type 1 (MEN1) is a rare inherited endocrine tumor syndrome principally affecting parathyroid glands, neuroendocrine tissues of the gastro-entero-pancreatic and thoracic tracts, and anterior pituitary, caused by germline inactivating mutations of the MEN1 tumor suppressor gene. Primary hyperparathyroidism (PHPT) is usually the first clinical manifestation of the syndrome, normally manifesting during the third decade of life. Cases of affected children and adolescents have been described by the age of 5. Clinical characteristics and therapeutic management of MEN1 in adolescents have been described mainly by case reports. Only two studies on MEN1 patient series under the age of 22 years have recently been published. Given the scarcity of data and the lack of a consistent number of targeted studies, there are currently no specific guidelines available for children and adolescents with MEN1; diagnostic and therapeutic management is, thus, usually the same as for adult patients. Here, we report our experience with 19 adolescent MEN1 patients, developing MEN1-associated PHPT before the age of 20. Fourteen of them, manifesting hypercalcemic PHPT before the age of 20 underwent parathyroidectomy before the age of 25 to control calcemia. Parathyroid surgery restored normal calcemia in all the operated patients. No post-surgical nephrolithiasis has been reported after a mean of 12.0 ± 5.8 years of follow-up. Comparison between pre-surgical and post-surgical values of bone mineral density (BMD) in 2 patients evidenced an improvement of bone mass after parathyroid adenoma ablation. Two patients (14.28%) developed permanent post-surgical hypoparathyroidism.

Increased Expression of GLP-1R in Proliferating Islets of Men1 Mice is Detectable by [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 /PET

Multiple endocrine neoplasia type 1 (MEN1) is an endocrine tumor syndrome caused by heterozygous mutations in the MEN1 tumor suppressor gene. The MEN1 pancreas of the adolescent gene carrier frequently contain diffusely spread pre-neoplasias and microadenomas, progressing to macroscopic and potentially malignant pancreatic neuroendocrine tumors (P-NET), which represents the major death cause in MEN1. The unveiling of the molecular mechanism of P-NET which is not currently understood fully to allow the optimization of diagnostics and treatment. Glucagon-like peptide 1 (GLP-1) pathway is essential in islet regeneration, i.e. inhibition of β-cell apoptosis and enhancement of β-cell proliferation, yet involvement of GLP-1 in MEN1 related P-NET has not yet been demonstrated. The objective of this work was to investigate if normal sized islets of Men1 heterozygous mice have increased Glucagon-like peptide-1 receptor (GLP-1R) expression compared to wild type islets, and if this increase is detectable in vivo with positron emission tomography (PET) using [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 (68Ga-Exendin-4). 68Ga-Exendin-4 showed potential for early lesion detection in MEN1 pancreas due to increased GLP1R expression.