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Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant familial cancer syndrome characterized primarily by endocrine tumors of the parathyroids, anterior pituitary, and enteropancreatic endocrine tissues. Affected individuals carry a germ-line loss-of-function mutation of the MEN1 gene, and tumors arise after loss of the second allele. Homozygous loss of Men1 in the germ line of mice results in early embryonic lethality, with defective development of neural tube, heart, liver, and craniofacial structures. We generated immortalized wild-type (WT) and menin-null mouse embryo fibroblast (MEF) cell lines and evaluated their characteristics, including global expression patterns. The WT and menin-null cell lines were aneuploid, and the nulls did not display tumorigenic characteristics in soft agar assay. Expression arrays in menin-null MEFs revealed altered expression of several extracellular matrix proteins that are critical in organogenesis. Specifically, transcripts for fibulin 2 (Fbln2), periostin (Postn), and versican [chondroitin sulfate proteoglycan (Cspg2)], genes critical for the developing heart and known to be induced by transforming growth factor-β (TGF-β), were decreased in their expression in menin-null MEFs. Fbln2 expression was the most affected, and the reduction in menin-null MEFs for Fbln2, Postn, and Cspg2 was 16.18-, 5.37-, and 2.15-fold, respectively. Menin-null MEFs also showed poor response to TGF-β–induced Smad3-mediated transcription in a reporter assay, supporting a role for menin in this pathway. Postn and Cspg2 expression in WT, unlike in null MEFs, increased on TGF-β treatment. The expression changes associated with the loss of the tumor suppressor menin provide insights into the defective organogenesis observed during early embryonic development in Men1-null mouse embryos. (Mol Cancer Res 2007;5(10):1041–51)

Supplementary Table S1 from Mouse Embryo Fibroblasts Lacking the Tumor Suppressor Menin Show Altered Expression of Extracellular Matrix Protein Genes

Supplementary Figures 1-4 from The Tumor Suppressor Protein Menin Inhibits AKT Activation by Regulating Its Cellular Localization

Context Parathyroid cancer (PC) is a rare endocrine neoplasm with high mortality. While surgery is the treatment for patients with the disease, recurrence rates are high, and patients usually succumb to severe hypercalcemia. There is no effective systemic therapy for the disease. Objective To investigate for novel genes causing parathyroid cancer. Methods We analyzed the germline DNA of 17 patients with “sporadic” PC and 3 with atypical parathyroid tumors (APTs) who did not have germline CDC73 or MEN1 pathogenic variants. Sequencing of available tumor tissue from 14 patients with PC and 2 with APT was also performed (including 2 patients with no available germline DNA). In addition, sporadic parathyroid adenomas from 74 patients were analyzed for FLCN variants. Results We identified germline FLCN variants in 3 unrelated patients with PC. The 2 frameshift variants have been described in patients with Birt-Hogg-Dubé (BHD) syndrome, while the pathogenicity of the missense variant c.124G > C (p.G42R) has not been definitively established. Functional analysis of the missense variant showed a potential effect on posttranslational modification. All 3 patients with germline FLCN variants were noted to have renal cysts and 2 had lung cysts, features associated with BHD syndrome. Somatic FLCN variants were identified in tumors from 2 (1 APT) of 16 patients with PC/APT and in none of the 74 sporadic parathyroid adenomas. No second hits in FLCN were noted on sequencing; however, loss of heterozygosity at the locus was demonstrated in 2 of 3 patients with the identified germline FLCN variant. Conclusion The finding of FLCN variants associated with PC may provide the foundation for the development of therapy for this malignancy.

Context Autologous implantation of parathyroid tissue is frequently utilized after parathyroidectomy in patients with heritable forms of primary hyperparathyroidism (PHPT). Data on long-term functional outcome of these grafts is sparse. Objective To investigate long-term outcomes of parathyroid autografts. Methods Retrospective study of patients with PHPT who underwent parathyroid autografts from 1991 to 2020. Results We identified 115 patients with PHPT who underwent 135 parathyroid autografts. Median follow-up duration since graft was 10 (4-20) years. Of the 111 grafts with known functional outcome, 54 (49%) were fully functional, 13 (12%) partially functional, and 44 (40%) nonfunctional at last follow-up. Age at time of graft, thymectomy prior to autograft, graft type (delayed vs immediate), or duration of cryopreservation did not predict functional outcome. There were 45 (83%) post-graft PHPT recurrences among 54 fully functional grafts at a median duration of 8 (4-15) years after grafting. Surgery was performed in 42/45 recurrences, but cure was attained in 18/42 (43%) only. Twelve of 18 (67%) recurrences were graft-related while remaining 6 (33%) had a neck or mediastinal source. Median time to recurrence was 16 (11-25) years in neck or mediastinal source vs 7 (2-13) years in graft-related recurrences. Median parathyroid hormone (PTH) gradient was significantly higher at 23 (20-27) in graft-related recurrence vs 1.3 (1.2-2.5) in neck or mediastinal source (P = .03). Conclusions Post-graft recurrence of PHPT occurs frequently within the first decade after graft and is challenging to localize. Time to recurrence after graft is significantly shorter and PTH gradient higher for graft-related recurrence. Clinical Trial Number: NCT04969926

Patients with the multiple endocrine neoplasia type 1 (MEN1) syndrome carry germline heterozygous loss-of-function mutations in the MEN1 gene which predisposes them to develop various endocrine and non-endocrine tumors. Over 90% of the tumors show loss of heterozygosity (LOH) at chromosome 11q13, the MEN1 locus, due to somatic loss of the wild-type MEN1 allele. Thymic neuroendocrine tumors (NETs) or thymic carcinoids are uncommon in MEN1 patients but are a major cause of mortality. LOH at the MEN1 locus has not been demonstrated in thymic tumors. The goal of this study was to investigate the molecular aspects of MEN1-associated thymic tumors including LOH at the MEN1 locus and RNA-sequencing (RNA-Seq) to identify genes associated with tumor development and potential targeted therapy. A retrospective chart review of 294 patients with MEN1 germline mutations identified 14 patients (4.8%) with thymic tumors (12 thymic NETs and 2 thymomas). LOH at the MEN1 locus was identified in 10 tumors including the 2 thymomas, demonstrating that somatic LOH at the MEN1 locus is also the mechanism for thymic tumor development. Unsupervised principal component analysis and hierarchical clustering of RNA-Seq data showed that thymic NETs formed a homogenous transcriptomic group separate from thymoma and normal thymus. KSR2 (kinase suppressor of Ras 2), that promotes Ras-mediated signaling, was abundantly expressed in thymic NETs, a potential therapeutic target. The molecular insights gained from our study about thymic tumors combined with similar data from other MEN1-associated tumors may lead to better surveillance and treatment of these rare tumors.

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) may occur in 30% to 90% of patients with multiple endocrine neoplasia type 1 (MEN1). However, only 1% of GEP-NETs are grade 3 (G3). Given the rarity of these aggressive tumors, treatment of advanced G3 GEP-NETs in MEN1 is based on the treatment guidelines for sporadic GEP-NETs. We report a 43-year-old male with germline MEN1 followed at our institution, with clinical features including hyperparathyroidism, a nonfunctional pancreatic NET, and Zollinger–Ellison syndrome. On routine surveillance imaging at age 40, computed tomography/positron emission tomography imaging showed 2 arterially enhancing intraluminal masses on the medial aspect of the gastric wall. Anatomical imaging confirmed 2 enhancing masses within the pancreas and a rounded mass-like thickening along the lesser curvature of the stomach. The gastric mass was resected, and pathology reported a well-differentiated G3 NET with a Ki-67 >20%. The patient continued active surveillance. Eighteen months later cross-sectional imaging studies showed findings consistent with metastatic disease within the right hepatic lobe and bland embolization was done. On follow-up scans, including 68Ga-DOTATATE (68Ga-DOTA(0)-Tyr(3)-octreotate) imaging, interval increase in number and avidity of metastatic lesions were compatible with disease progression. Given a paucity of treatment recommendations for G3 tumors in MEN1, the patient was counseled based on standard NET treatment guidelines and recommended 177Lu-DOTATATE treatment. PRRT (peptide receptor radionuclide therapy) with 177Lu-DOTATATE (177Lu-tetraazacyclododecanetetraacetic acid-octreotide) is an important therapeutic modality for patients with somatostatin receptor–positive NETs. However, prospective studies are needed to understand the role of PRRT in G3 NETs.

Introduction Recurrent and metastatic pheochromocytoma (PCC) are rare advanced endocrine neoplasms with limited treatment options. Insight into the pathogenic molecular alterations in patients with advanced PCC can provide therapeutic options for precisely targeting dysregulated pathways. Objective We report the discovery and characterization of a novel BRAF-containing fusion transcript and its downstream molecular alterations in a patient with recurrent PCC with peritoneal seeding (pheochromocytomatosis). Methods We reviewed the medical record of a patient with pheochromocytomatosis. A comprehensive pan-cancer molecular profiling using next-generation sequencing (NGS) as well as confirmatory real-time-quantitative PCR were performed on surgical specimens. BRAF rearrangement and downstream molecular changes were assayed using fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. Western blot was used to assess the in vitro activation of the mitogen-activated protein kinase (MAPK) signaling pathway and the EMT markers in transfected HEK-293 cells. Results The NGS analysis of a specimen from a 72-year-old female patient with pheochromocytomatosis showed an in-frame fusion of exon 3 of Glucocorticoid Induced 1 (GLCCI1) to exon 9 of BRAF. The upstream auto-inhibitory domain of BRAF was excluded from the GLCCI1-BRAF fusion; however, the downstream BRAF kinase domain was intact. A BRAF rearrangement was confirmed via a BRAF-specific break-apart FISH assay. Four separate tumor foci harbored GLCCI1-BRAF fusion. IHC demonstrated increased phosphorylated MEK. HEK-293 cells transfected with the GLCCI1-BRAF fusion demonstrated increased phosphorylated MEK as well as higher expression of EMT markers SNAI1 and ZEB1 in vitro. Conclusion We demonstrate a novel pathogenic gene fusion of GLCCI1 with the oncogenic kinase domain of BRAF, resulting in an activation of the MAPK signaling pathway and EMT markers. Thus, this patient may benefit from clinically available MEK and/or BRAF inhibitors when systemic therapy is indicated. Summary statement This report is the first of GLCCI1 fused to BRAF in a human neoplasm and only the second BRAF-containing fusion transcript in PCC. Detailed molecular characterization of PCC can be a valuable tool in managing patients with recurrent PCC and pheochromocytomatosis that represents a significant clinical challenge.

Multiple endocrine neoplasia type 1 (MEN1), a rare tumor syndrome that is inherited in an autosomal dominant pattern, is continuing to raise great interest for endocrinology, gastroenterology, surgery, radiology, genetics, and molecular biology specialists. There have been 2 major clinical practice guidance papers published in the past 2 decades, with the most recent published 8 years ago. Since then, several new insights on the basic biology and clinical features of MEN1 have appeared in the literature, and those data are discussed in this review. The genetic and molecular interactions of the MEN1-encoded protein menin with transcription factors and chromatin-modifying proteins in cell signaling pathways mediated by transforming growth factor β/bone morphogenetic protein, a few nuclear receptors, Wnt/β-catenin, and Hedgehog, and preclinical studies in mouse models have facilitated the understanding of the pathogenesis of MEN1-associated tumors and potential pharmacological interventions. The advancements in genetic diagnosis have offered a chance to recognize MEN1-related conditions in germline MEN1 mutation–negative patients. There is rapidly accumulating knowledge about clinical presentation in children, adolescents, and pregnancy that is translatable into the management of these very fragile patients. The discoveries about the genetic and molecular signatures of sporadic neuroendocrine tumors support the development of clinical trials with novel targeted therapies, along with advancements in diagnostic tools and surgical approaches. Finally, quality of life studies in patients affected by MEN1 and related conditions represent an effort necessary to develop a pharmacoeconomic interpretation of the problem. Because advances are being made both broadly and in focused areas, this timely review presents and discusses those studies collectively.

Gastroenteropancreatic neuroendocrine tumors (GEP NETs) comprise a heterogenous and diverse group of neoplasms arising from a common neuroendocrine cell origin. The majority of these tumors occur sporadically while ~20% manifest within the context of hereditary syndromes. Germline MEN1 mutations cause a syndrome with an increased susceptibility to multifocal primary GEP NETs. In addition, somatic MEN1 mutations also occur in these sporadic lesions. MEN1 alterations are the most frequent somatic mutation found in pancreatic neuroendocrine tumors. In this review, we explore the implication of the loss of the MEN1-encoded protein menin as a key pathogenic driver in subsets of GEP NETs with downstream consequences including upregulation of the oncogenic receptor c-MET (hepatocyte growth factor receptor). Furthermore, the review will summarize the data related to the clinical presentation, therapeutic standards, and outcomes of these tumors in both sporadic and germline MEN1 mutation-associated contexts. Finally, we present the data on c-MET expression in GEP NETs, clinical trials using c-MET inhibitors and provide an overview of the molecular mechanisms by which c-MET inhibition in these lesions represents a potential precision-medicine targeted approach.

Multiple studies have shown that approximately 50-70% of patients with MEN1 die of causes directly related to MEN1 particularly gastroenteropancreatic (GEP) neuroendocrine tumors (NETs). While non-functional GEP-NETs are the most common in the general population, gastrinomas (40%) are the most common functional GEP-NETs in patients with MEN1. c-MET is a proto-oncogene that encodes for c-MET, a tyrosine kinase receptor which promotes tumor cell motility, proliferation, survival, invasion, and metastasis. Studies in patients with sporadic gastrinomas and pancreatic NETs (PNETs) have shown that c-MET expression correlates with decreased survival. While c-MET inhibitors are currently in various stages of investigation for treatment of carcinoids and sporadic PNETs, data regarding their efficacy in patients with MEN1-related GEP NETs is lacking. The majority of trials in patients with GEP-NETs exclude or do not report the number of patients with MEN1. Importantly, somatic MEN1 mutations are observed in 20-40% of sporadic NETs (gastrinomas, PNETs, lung NETs, etc.) but correlation of cMET expression with the presence of somatic or germline MEN1 mutations has not been reported. We sought to investigate the expression of c-MET in tumor tissue from germline MEN1 patients with metastatic GEP-NETs. Methods We identified subjects with a germline positive MEN1 mutation and pathologically confirmed distant metastasis who had a follow-up visit between 2018-2020. Of these, we selected subjects with available tissue specimens (including either multiple organ sources or different tumor types). Where available, we identified specimens from multiple source or tumor types. Immunohistochemistry (IHC) to detect c-MET was performed with anti-MET (Cell Signaling) using the DAKO IHC kit (Agilent). IHC slides were imaged and observed to score the level of c-MET staining (-, 1+ to 5+). A score of 3+ or higher was considered consistent with overexpression. We investigated if age at initial GEP-NET presentation, tumor type, tissue source, tumor grade, total number of surgeries for GEP-NET, number of sites of distant metastasis and disease status from overall GEP-NET burden over the preceding 12 months (stable/progressive) predicted c-MET expression. Results Eight subjects with available tissue specimens were identified, of which six had tissue from multiple organs while five had tissue from multiple tumor types. Six subjects (75%) showed increased expression of c-MET in one or more tumor specimen(s). The frequency of c-MET overexpression varied with tumor types – carcinoids (n=2/2; 100%), gastrinomas (n=3/5; 60%) and non-functional tumors (n=3/6; 50%). c-MET expression also varied among different tumors in the same patient. Tumor tissue from liver (n=2/2), duodenum (n=3/4), stomach (n=1/1), ovary (n=1/1), pancreas (n= 1/5), and lymph nodes (n=1/3), all showed over-expression of c-MET. No clear predictors of c-MET overexpression emerged. Conclusion Our finding suggests a role for c-MET expression in personalizing therapy for patients with MEN1-related NETs with distant metastases. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Sunday, June 12, 2022 12:48 p.m. - 12:53 p.m.

Multiple Endocine Neoplasia Type 1 (MEN1) is associated with duodenopancreatic neuroendocrine tumors (dpNETs) and metastatic dpNET is the primary cause of disease-related mortality for this condition. Currently, there is a paucity of prognostic factors that can reliably identify patients with MEN1-related dpNETS who are at high risk of distant metastasis. Previously, we uncovered a blood-based polyamine metabolite signature that was associated with MEN1-dpNET disease progression. In the current study, we aimed to build upon our prior findings, by exploring the contributions of proteomics for identifying circulating protein markers associated with tumor progression. We performed in-depth proteomic analysis of serially collected plasmas from a genetically engineered mouse model of Men1-pNET, Men1fl/flPdx1-CreTg, and Men1fl/fl control mice to assess dynamic changes in the plasma proteome that associated with disease progression. Findings were compared to plasma proteomic profiles from a cohort of 56 patients with MEN1 (14 with distant metastasis dpNETs (cases) and 42 with either indolent dpNETs or no dpNETs (controls)). Analyses revealed 196 proteins related to oncogenic N-MYC, YAP1, POU5F1, and SMAD that were positively associated with pNET disease progression in Men1fl/flPdx1-CreTg mice. Similarly, 187 proteins were elevated in MEN1 patients with distant metastasis compared controls. Proteins with increased levels in metastatic cases included AMY2B, CELA3B, RNASE1, IGFBP2, CHI3L1, LYZ, TIMP1, LRG1, and COL18A1 previously associated with pancreatic cancer and other neuronal proteins. Cross-species intersection revealed 19 proteins including NDC80, DEF8, SPAG17, ATM, IMMT, DNAH6, DSP, CIT, HRG, CD79A, BDP1, SERPINA11, TARBP1, and SERPIND1 that were positively associated with disease progression in Men1fl/flPdx1-CreTg mice and human subjects. Our integrated analyses identified novel circulating protein features associated with disease progression in MEN1-related dpNET. Citation Format: Johannes F. Fahrmann, Amanda R. Wasylishen, Carolina R.C. Pieterman, Ehsan Irajizad, Jody Vykoukal, Ranran Wu, Jennifer D. Dennison, Christine B. Peterson, Guillermina Lozano, Hua Zhao, Kim-Ahn Do, Daniel M. Halperin, Sunita K. Agarwal, Jenny E. Blau, Jaydira D. Rivero, Naris Nilubol, Mary F. Walter, James M. Welch, Lee S. Weinstein, Menno R. Vriens, Rachel S. van Leeuwaarde, Mark J.C. van Treijen, Gerlof D. Valk, Nancy D. Perrier, Sam M Hanash, Hiroyuki Katayama. Blood-based proteomic signatures associated with MEN1-related duodenopancreatic neuroendocrine tumor progression. [abstract]. In: Proceedings of the AACR Special Conference: Precision Prevention, Early Detection, and Interception of Cancer; 2022 Nov 17-19; Austin, TX. Philadelphia (PA): AACR; Can Prev Res 2023;16(1 Suppl): Abstract nr P066.

Context Duodenopancreatic neuroendocrine tumors (dpNETs) frequently occur in patients with multiple endocrine neoplasia type 1 (MEN1), and metastatic dpNET is the primary cause of disease-related mortality. There is a need for biomarkers that can identify patients with MEN1-related dpNETs that are at high risk of developing distant metastasis. Polyamines have tumor-promoting roles in several cancer types. Objective We hypothesized that MEN1-dpNET–related disease progression is associated with elevated levels of circulating polyamines. Methods Through an international collaboration between The University of Texas MD Anderson Cancer Center, the National Institutes of Health, and the University Medical Center Utrecht, plasma polyamine levels were assessed using mass spectrometry in 84 patients with MEN1 (20 with distant metastatic dpNETs [patients] and 64 with either indolent dpNETs or no dpNETs [controls]). A mouse model of MEN1-pNET, Men1fl/flPdx1-CreTg, was used to test time-dependent changes in plasma polyamines associated with disease progression. Results A 3-marker plasma polyamine signature (3MP: N-acetylputrescine, acetylspermidine, and diacetylspermidine) distinguished patients with metastatic dpNETs from controls in an initial set of plasmas from the 3 participating centers. The fixed 3MP yielded an area under the curve of 0.84 (95% CI, 0.62-1.00) with 66.7% sensitivity at 95% specificity for distinguishing patients from controls in an independent test set from MDACC. In Men1fl/flPdx1-CreTg mice, the 3MP was elevated early and remained high during disease progression. Conclusion Our findings provide a basis for prospective testing of blood-based polyamines as a potential means for monitoring patients with MEN1 for harboring or developing aggressive disease.

Pancreatic neuroendocrine tumors (PNETs) are classified based on their histologic differentiation and proliferative indices, which have been used extensively to determine prognosis. Advances in next-generation sequencing and other high-throughput techniques have allowed researchers to objectively explore tumor specimens and learn about the genetic alterations associated with malignant transformation in PNETs. As a result, targeted, pathway-specific therapies have been emerging for the treatment of unresectable and metastatic disease. As we continue to trial various pharmaceutical products, evidence from studies using multi-omics approaches indicates that clinical aggressiveness stratifies along other genotypic and phenotypic demarcations, as well. In this review, we explore the clinically relevant and potentially targetable molecular signatures of PNETs, their associated trials, and the overall differences in reported prognoses and responses to existing therapies.

Purpose To compare the deoxyribonucleic acid (DNA) methylation signature of neuroendocrine tumors (NETs) by primary tumor site and inherited predisposition syndromes von Hippel–Lindau disease (VHL) and multiple endocrine neoplasia type 1 (MEN1). Methods Genome-wide DNA methylation (835 424 CpGs) of 96 NET samples. Principal components analysis (PCA) and unsupervised hierarchical clustering analyses were used to determine DNA methylome signatures. Results Hypomethylated CpGs were significantly more common in VHL-related versus sporadic and MEN1-related NETs (P < .001 for both comparisons). Small-intestinal NETs (SINETs) had the most differentially methylated CpGs, either hyper- or hypomethylated, followed by duodenal NETs (DNETs) and pancreatic NETs (PNETs, P < .001 for all comparisons). There was complete separation of SINETs on PCA, and 3 NETs of unknown origin clustered with the SINET samples. Sporadic, VHL-related, and MEN1-related PNETs formed distinct groups on PCA, and VHL clustered separately, showing pronounced DNA hypomethylation, while sporadic and MEN1-related NETs clustered together. MEN1-related PNETs, DNETs, and gastric NETs each had a distinct DNA methylome signature, with complete separation by PCA and unsupervised clustering. Finally, we identified 12 hypermethylated CpGs in the 1A promoter of the APC (adenomatous polyposis coli) gene, with higher methylation levels in MEN1-related NETs versus VHL-related and sporadic NETs (P < .001 for both comparisons). Conclusions DNA CpG methylation profiles are unique in different primary NET types even when occurring in MEN1-related NETs. This tumor DNA methylome signature may be utilized for noninvasive molecular characterization of NETs, through DNA methylation profiling of biopsy samples or even circulating tumor DNA in the near future.

Objective There is scant data of the genome-wide methylome alterations in neuroendocrine tumors (NET). Thus, the goal of this study was to compare the DNA methylation signature of NETs with respect to various primary sites and inherited genetic predisposition syndromes including von Hippel-Lindau (VHL) and multiple endocrine neoplasia type 1 (MEN1). Methods Genome-wide DNA methylation analysis of 96 NETs (primary and metastatic) was performed by using the Illumina Infinium EPIC Array. Principal component analysis (PCA) and unsupervised clustering analyses were performed to identify distinct methylome signatures. The methylation status of genetic drivers such as APC were assessed by primary site. Results A total of 835,424 CpGs methylation sites were quantified. Hypermethylated CpG sites were detected more frequently in sporadic vs. MEN1-related vs. VHL-related NETs, respectively (p < 0.001 for all comparisons), while hypomethylated CpGs sites were more common in VHL-related NETs vs. sporadic and MEN1-related NETs (p Small-intestinal NETs (SINETs) had the most differences at CpGs with the highest number of hyper- and hypomethylated CpG sites, followed by duodenal NETs (DNETs) and pancreatic NETs (PNETs, p Conclusion Various primary NET sites and genetically predisposed MEN1-related NETs have distinct DNA CpG methylation signatures. The methylome signatures identified in this study may be useful for non-invasive molecular characterization of NETs, through DNA methylation profiling of biopsy samples or circulating tumor DNA.

Background: Here we describe a patient who presented with symptomatic hypocalcemia and a biochemical picture suggestive of PTH resistance. PTH resistance is a hallmark of pseudohypoparathyroidism, a heterogeneous group of rare disorders caused by genetic or epigenetic alterations of PTH/PTHrP signaling. However, PTH receptor-related autoimmune etiology has not been identified as the underlying mechanism for PTH resistance. Here we describe the first case of acquired autoimmune PTH resistance that is secondary to PTH1R autoantibodies. Clinical Case: A 60-year-old African-American woman, who previously had normal calcium homeostasis, presented with acute, symptomatic hypocalcemia, hyperphosphatemia and markedly elevated serum PTH, consistent with parathyroid hormone resistance. She did not have other hormone resistance or a clinical phenotype suggestive of pseudohypoparathyroidism. Whole-exome sequencing and GNAS methylation analysis revealed no genetic or epigenetic defects of the PTH/PTHrP signaling pathway. Treatment with Calcitriol and Calcium supplements was initiated with good clinical response. Within 10 years of follow-up, the patient developed autoimmune hypothyroidism, alopecia and an unusual form of membranous glomerulonephritis, raising the suspicion for an autoimmune etiology for PTH resistance. Luciferase immunoprecipitation system assay identified antibodies against PTH1R with mapping to the N-terminal extracellular ligand-binding domain (amino acids 1- 178). Using an in vitro biological assay in GP-2.3 cells, we found that the antibodies derived from the patient’s serum blocked PTH downstream signaling via Gsalpha/cAMP/protein kinase A pathway in a concentration-dependent manner. The patient’s autoantibody profile led to the diagnosis of additional autoimmune diseases, including atrophic gastritis and Sjogren syndrome. Lymphocyte immunophenotyping using flow cytometry revealed an overall normal B and T cell profile, but with decreased frequencies and numbers of switched and non-switched memory B cell subsets and an increased frequency and number of the CD8+ naïve cell population. Genes associated with autoimmune inflammatory disorders were sequenced but no pathologic changes were detected. Conclusions: Identification of the first case of autoimmune PTH resistance secondary to PTH1R autoantibodies extends the etiologic spectrum of hypoparathyroidism and should be considered when a patient presents with findings consistent with pseudohypoparathyroidism, especially in the presence of additional autoimmune diseases.

Background: Neuroendocrine neoplasms (NEN) are a heterogenous group of tumors. Patients with the multiple endocrine neoplasia type 1 (MEN1) syndrome often manifest with simultaneous functional and non-functional NEN in various endocrine glands. In MEN1, nuclear medicine plays an important role in the diagnostic work-up and localization of NEN. Little is known about the comparative efficacy of 68Ga-Dotatate PET/CT (DOTA) versus 18F-FDOPA PET/CT (FDOPA) and both versus non-nuclear medicine imaging (CT and MRI) in the identification of primary and metastatic NEN. Methods: This prospective MEN1 cohort study evaluated 15 germline MEN1 mutation-positive patients. Subjects were imaged using CT, MRI, DOTA and 18F-FDOPA. Radiological review with a multidisciplinary team was performed for each patient. Results: One-hundred twenty-nine total lesions were identified using any of the four scans. DOTA sensitivity was 69% (89/129; 95% CI 61% to 76%) with a mean standardized uptake value (SUV) of 33.9 ± 30.1, FDOPA sensitivity was 18% (23/129; 95% CI 12% to 25%) with mean SUV of 12.1 ± 15.16. DOTA identified an additional 50 lesions not seen on CT (of which MRI detected 8 lesions with an average size 0.95 cm ± 0.48; 3 pancreatic, 2 duodenal, 2 liver, and 1 lymph node) and identified 55 lesions not seen on MRI (of which CT identified 13 with a mean size of 1.1 cm ± 0.45; 1 lung, 4 pancreatic, 2 duodenal, 1 liver, and 5 lymph nodes). Overall, CT detected 51.2% (66/129) of lesions (mean 0.61 cm ± 0.73; 95% CI 43% to 60%) and MRI detected 39.5% (51/129; 0.47 cm ± 0.71; 95% CI 32% to 48%), and there was no significant difference in the size of lesions detected (p=0.18). Analysis by organ NEN revealed equal sensitivity between FDOPA and DOTA for lung carcinoid, detecting 33% (4/12) of lesions, while CT detected 92% (11/12) of lesions. In the duodenum, DOTA identified 100% (11 /11) of lesions, while FDOPA had poor sensitivity (9%) in this location. Within the pancreas, DOTA has a sensitivity of 81% (31/38), while FDOPA had a sensitivity of 21% (8/38). CT localized 42% (16/38) of pancreatic lesions, of which MRI missed 6. Interestingly, DOTA missed 7 pancreatic lesions all approximately 1cm or larger, which is previously unrecognized (range 0.9 - 1.8cm). Twenty-three liver metastases were detected on anatomic imaging (CT identified 14, while MRI detected 15, with only 9 overlapping lesions). DOTA identified 60% (14/23) of lesions, of which 3 lesions were missed by CT and MRI. However, DOTA was more sensitive in the liver than FDOPA which only detected 2 lesions. FDOPA detected one lesion in the adrenal (0.9cm) that was not seen on DOTA. Conclusion: DOTA imaging proved to be superior to FDOPA, CT and MRI overall in detecting NENs in MEN1, specifically in the duodenum. Pancreatic NEN missed by DOTA may represent higher grade tumors and may benefit from 18FDG PET/CT imaging.

Background: Multiple endocrine neoplasia type 1 (MEN1) is a rare inherited disorder in which patients develop multiple simultaneous hormone-secreting tumors. Most common tumors include: anterior pituitary adenomas (50%), multi-gland parathyroid adenomas (95%), and gastroenteropancreatic neuroendocrine tumors (40-80%). Only rare MEN1 associated glucagonomas ( Methods: We queried a prospective natural history study of MEN1 patients who tested positive for germline MEN1 mutations (n=287) between 1991-2019 (54 patients on our current protocol were followed before 1991; the earliest was 1971). All lifetime events of VTE were included. Search terms included: DVT, thromb, embol, PE, pulmonary embolism, clot, hematology consult, anticoagulant, coumadin, lovenox, xarelto, warfarin, aspirin, rivaroxaban and apixaban. After initial screening, 10 patients were removed due to insufficient clinical data. Kaplan-Meier analysis was performed to compare age of death between the two cohorts. Results were expressed as mean ± standard deviation. Results: Thirty-four subjects (mean 57.5 years-old, 17 women) were identified with any VTE, yielding a prevalence rate of 13.4%. The incidence of VTE corresponded to 264 events per 100,000 patient-years, which was ~2-fold higher than the estimated annual incidence rate in the general population (104-183/100,000 patient years).1 Kaplan-Meier analysis revealed no significant difference in survival between the two groups (non-VTE cohort mean 81.1 years ± 2.23; VTE cohort mean 77.4 years ± 3.45; p = 0.96). Thirty-two events occurred during the surveillance period at our institution; 9 individuals had more than one VTE. At the time of VTE, 80% had hyperparathyroidism (mean PTH ± SD; 97.56 pg/mL ± 90.76), 21% had hyperprolactinemia (prolactin 25.7μg/L ± 43.41), 62.5% had hypergastrinemia (mean gastrin 1100.9 pg/mL ± 3127.8), and 84.6% had non-functional pancreatic neuroendocrine tumors. One patient was identified to have a Factor V Leiden mutation, 3 patients had lupus anti-coagulant. Eleven patients experienced events within a post-surgical period of 3 months. Conclusions: Hypercoagulability in MEN1 has been previously unidentified. Our cohort data suggests a two-fold increase in the incidence of VTE as compared to the general population, with a high risk occurring within the perioperative period. Further mechanistic investigation and validation from other cohorts are needed to confirm the increased prevalence of VTE in this population. 1Heit, John A., et al. Epidemiology of venous thromboembolism. Nat Rev Cardiol 2015 Aug;12(8): 464-474.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant syndrome characterized by hyperparathyroidism, pituitary adenomas, and gastro-entero-pancreatic neuroendocrine tumors. Patients with MEN1 mutations have impaired glucose homeostasis, but the role of insulin resistance and beta-cell function is unclear. METHODS: Using a case-control study design, a retrospective analysis of germline mutation-positive MEN 1 patients (n=289) seen at our institution between 1991-2019 was performed. Patients with diabetes and/or insulinoma were excluded. Subjects were age, BMI, sex and race matched 1:1 to unrelated, healthy controls. Fasting glucose, insulin, c-peptide, calcium, PTH, 25-OH vitamin D, cholesterol, LDL, HDL and triglycerides (TG) were compared between two groups. Homeostasis model assessment (HOMA-IR) and HOMA-beta cell function (HOMA-b) were used as surrogate measures of insulin resistance and beta-cell function, respectively. Data is presented as mean ± SD. RESULTS: MEN1 subjects (n=40; age 41±11 years; BMI 29.2±7.2 kg/m2) were matched to healthy controls (age 41±11 years; BMI 29.1±7.5 kg/m2). Only 3 MEN1 patients had no evidence of pancreatic neuroendocrine tumors. Impaired fasting glucose was more prevalent in MEN1 compared with controls (53% vs 10%, p CONCLUSION: Lower insulin sensitivity, but not impaired beta cell function may contribute to the higher prevalence of impaired fasting glucose in MEN1 patients compared with controls. Mechanistic studies into the role of menin loss in glucose homeostasis are warranted.

Summary Pheochromocytoma (PHEO) in multiple endocrine neoplasia type 1 (MEN1) is extremely rare. The incidence is reported as less than 2%. We report a case of a 76-year-old male with familial MEN1 who was found to have unilateral PHEO. Although the patient was normotensive and asymptomatic, routine screening imaging with CT demonstrated bilateral adrenal masses. The left adrenal mass grew from 2.5 to 3.9 cm over 4 years with attenuation values of 9 Hounsfield units (HU) pre-contrast and 15 HU post-contrast washout. Laboratory evaluation demonstrated an adrenergic biochemical phenotype. Both 18F-fluorodeoxyglucose (18F-FDG) PET/CT and 123I-metaiodobenzylguanidine (123I-mIBG) scintigraphy demonstrated bilateral adrenal uptake. In contrast, 18F-fluorodihydroxyphenylalanine (18F-FDOPA) PET/CT demonstrated unilateral left adrenal uptake (28.7 standardized uptake value (SUV)) and physiologic right adrenal uptake. The patient underwent an uneventful left adrenalectomy with pathology consistent for PHEO. Post-operatively, he had biochemical normalization. A review of the literature suggests that adrenal tumors >2 cm may be at higher risk for pheochromocytoma in patients with MEN1. Despite a lack of symptoms related to catecholamine excess, enlarging adrenal nodules should be biochemically screened for PHEO. 18F-FDOPA PET/CT may be beneficial for localization in these patients. Learning points: 18F-FDOPA PET/CT is a beneficial imaging modality for identifying pheochromocytoma in MEN1 patients. Adrenal adenomas should undergo routine biochemical workup for PHEO in MEN1 and can have serious peri-operative complications if not recognized, given that MEN1 patients undergo frequent surgical interventions. MEN1 is implicated in the tumorigenesis of PHEO in this patient.

Purpose: Mitochondrial glycerophosphate dehydrogenase (MGPDH) is the key enzyme connecting oxidative phosphorylation (OXPHOS) and glycolysis as well as a target of the antidiabetic drug metformin in the liver. There are no data on the expression and role of MGPDH as a metformin target in cancer. In this study, we evaluated MGPDH as a potential target of metformin in thyroid cancer and investigated its contribution in thyroid cancer metabolism. Experimental Design: We analyzed MGPDH expression in 253 thyroid cancer and normal tissues by immunostaining and examined its expression and localization in thyroid cancer–derived cell lines (FTC133, BCPAP) by confocal microscopy. The effects of metformin on MGPDH expression were determined by qRT-PCR and Western blot analysis. Seahorse analyzer was utilized to assess the effects of metformin on OXPHOS and glycolysis in thyroid cancer cells. We analyzed the effects of metformin on tumor growth and MGPDH expression in metastatic thyroid cancer mouse models. Results: We show for the first time that MGPDH is overexpressed in thyroid cancer compared with normal thyroid. We demonstrate that MGPDH regulates human thyroid cancer cell growth and OXPHOS rate in vitro. Metformin treatment is associated with downregulation of MGPDH expression and inhibition of OXPHOS in thyroid cancer in vitro. Cells characterized by high MGPDH expression are more sensitive to OXPHOS-inhibitory effects of metformin in vitro and growth-inhibitory effects of metformin in vitro and in vivo. Conclusions: Our study established MGPDH as a novel regulator of thyroid cancer growth and metabolism that can be effectively targeted by metformin. Clin Cancer Res; 24(16); 4030–43. ©2018 AACR.

Epigenetic regulation is emerging as a key feature in the molecular characteristics of various human diseases. Epigenetic aberrations can occur from mutations in genes associated with epigenetic regulation, improper deposition, removal or reading of histone modifications, DNA methylation/demethylation and impaired non-coding RNA interactions in chromatin. Menin, the protein product of the gene causative for the multiple endocrine neoplasia type 1 (MEN1) syndrome, interacts with chromatin-associated protein complexes and also regulates some non-coding RNAs, thus participating in epigenetic control mechanisms. Germline inactivating mutations in theMEN1gene that encodes menin predispose patients to develop endocrine tumors of the parathyroids, anterior pituitary and the duodenopancreatic neuroendocrine tissues. Therefore, functional loss of menin in the various MEN1-associated endocrine cell types can result in epigenetic changes that promote tumorigenesis. Because epigenetic changes are reversible, they can be targeted to develop therapeutics for restoring the tumor epigenome to the normal state. Irrespective of whether epigenetic alterations are the cause or consequence of the tumorigenesis process, targeting the endocrine tumor-associated epigenome offers opportunities for exploring therapeutic options. This review presents epigenetic control mechanisms relevant to the interactions and targets of menin, and the contribution of epigenetics in the tumorigenesis of endocrine cell types from menin loss.

Background Approximately 10% of patients with primary hyperparathyroidism (PHPT) have hereditary disease. Hereditary PHPT may be syndromic (MEN1, 2, and 4 and hyperparathyroidism-jaw tumor syndrome) or non-syndromic (familial isolated PHPT). There are limited data on the probability of testing positive for genetic mutation based on clinical presentation. The aim of this study was to determine potential associations between clinical and biochemical features and mutation in susceptibility genes for PHPT in patients with a family history of PHPT. Study Design A retrospective analysis of 657 patients who had an initial parathyroidectomy for PHPT at a tertiary referral center. Logistic regression analyses were performed in 205 patients with a family history of PHPT to identify factors associated with a positive genetic test. Results Of 657 patients, 205 (31.2%) had a family history of PHPT. Of those 205 patients, 123 (60%) had a germline mutation detected (91 MEN1 , 14 CDC73 , and 18 GCM2 ). In univariate analysis, younger age (45 years and younger), male sex, multigland disease, and parathyroid carcinoma were associated with positive germline mutation; biochemical cure after an initial parathyroidectomy was less frequent in patients with familial PHPT (96.2% vs 89.2%; p = 0.005). In multivariable analysis, age 45 years and younger, male sex, and multigland disease were independent factors associated with positive genetic testing. Conclusions In addition to a family history of PHPT, male sex, age 45 years and younger, and presence of multigland disease, should prompt physicians to offer the opportunity for genetic counseling and testing, as it could influence the management of patients with PHPT.

Background: Multiple endocrine neoplasia type 1 (MEN1) is an inherited tumor syndrome with autosomal dominant inheritance. Thymic neuroendocrine tumors (NETs) are known manifestations of MEN1 occurring in 2-8% of patients. However, thymomas, a type of thymic epithelial tumors, have only been described in rare case reports. They markedly differ from thymic NETs in their natural history, morphology, prognosis, and therapeutic options. Here we present a case of an aggressive, recurrent thymoma associated with MEN1. Case Report: A 58-year-old Caucasian female with a family history of MEN1 was diagnosed with a prolactinoma at age 15 when she presented with irregular menses, galactorrhea, headaches and visual field defects. She was referred to our institution for further evaluation where genetic testing confirmed the diagnosis of MEN1. Throughout the years, she developed primary hyperparathyroidism, non-functional pancreatic neuroendocrine tumors, Zollinger-Ellison syndrome, bilateral adrenal hyperplasia, and bronchial carcinoid. At the age of 49, magnetic resonance imaging (MRI) and computed tomography (CT) scan of the chest incidentally demonstrated a 2.5 x 6 x 10-cm anterior mediastinal mass, with marked compression of the left brachiocephalic vein and encasement of the superior vena cava. Biopsy was consistent for malignant cells of thymic epithelial origin. A median sternotomy with en bloc resection with SVC resection and reconstruction, mediastinal lymph node dissection and placation of the right hemidiaphragm were performed. Pathology revealed WHO type B3 thymoma extending into the pulmonary parenchyma with positive tissue margins but negative lymph node involvement. Following surgery, she underwent adjuvant radiation therapy with a total dose of 59 Gy. Annual screening showed disease remission. However, nine years after initial presentation, surveillance CT scans revealed a pleural base mass with mass effect on the superior portion of the IVC, as well as hypoattenuated masses within the liver. Positron emission tomography with fluorodeoxyglucose (18FDG PET-CT) confirmed multiple metastatic lesions involving thorax and abdomen. Biopsy of the retrocaval soft tissue subxiphoid mass revealed epithelioid cells in a background of lymphocytes consistent with recurrent thymoma. She was subsequently staged as IV B thymoma and was recommended to start systemic chemotherapy. Conclusion: We described a case of an aggressive thymoma in a patient with MEN1 syndrome demonstrating that their association exists and the clinical presentation can be aggressive. Thus, it is important for practitioners to screen for thymic tumors routinely in patients with MEN1 for early detection as they can be a major cause of mortality. Although further studies are needed, improving the detection of these tumors could significantly contribute to reducing MEN1-related deaths.

The insulin-secreting pancreatic neuroendocrine tumors, insulinomas, characterized by increased pancreatic islet β-cell proliferation, express the phosphorylated isoform of the β-cell differentiation factor HLXB9 that interacts with NONO/p54NRB, a survival factor. Interestingly, two different homozygous germline mutations in HLXB9, p.F248L and p.F272L, were reported in neonatal diabetes, a condition with functional β-cell deficiency. Also, two somatic heterozygous NONO mutations were found in endocrine-related tumors, p.H146R (parathyroid) and p.R293H (small intestine neuroendocrine tumor). However, the biological consequence of the mutations, and the role of HLXB9-NONO interaction in normal or abnormal β cells, is not known. Expression, localization, and functional analysis of the clinically relevant HLXB9 and NONO mutants showed that HLXB9/p.F248L mutant localized in the nucleus but lacked phosphorylation, and NONO/p.R293H mutant was structurally impaired. The HLXB9 and NONO mutants retained the ability to interact, and overexpression of wild-type or mutant HXLB9 in MIN6 cells suppressed cell proliferation. To further understand the biological consequence of the HLXB9-NONO interaction, we mapped the NONO-interacting region in HLXB9. An 80–amino acid conserved region of HLXB9 could compete with full-length HLXB9 to interact with NONO; however, in functional assays, nuclear expression of this HLXB9-conserved region in MIN6 cells did not interfere with cell proliferation. Overall, our results highlight the importance of HLXB9 in conditions of β-cell excess (insulinomas) and in conditions of β-cell loss or dysfunction (diabetes). Our studies implicate therapeutic strategies for either reducing β-cell proliferation in insulinomas or alleviating normal β-cell deficiency in diabetes through the modulation of HLXB9 phosphorylation., Functional analysis showed that one of two HLXB9 mutations found in neonatal diabetes blocked phosphorylation and one of two NONO mutations found in endocrine tumors perturbed protein structure.

BACKGROUND Nonfunctioning pancreatic neuroendocrine tumors (NFPanNETs) may be sporadic or inherited because of germline mutations associated with von Hippel-Lindau disease (VHL) or multiple endocrine neoplasia type 1 (MEN1). The clinical behavior of NFPanNETs is difficult to predict, even in tumors of the same stage and grade. The authors analyzed genotype-specific patterns of transcriptional messenger RNA (mRNA) levels of NFPanNETs to understand the molecular features that determine PanNET phenotype. METHODS Thirty-two samples were included for genome-wide mRNA gene expression analysis (9 VHL-associated, 10 MEN1-associated, and 9 sporadic NFPanNETs and 4 purified normal islet cell [NIC] samples). Validation of genes was performed by real-time polymerase chain reaction analysis and immunohistochemistry. Gene expression profiles were analyzed by tumor genotype, and pathway analysis was curated. RESULTS Consensus clustering of mRNA expression revealed separate clustering of NICs, VHL-associated NFPanNETs, and MEN1-associated NFPanNETs; whereas some sporadic tumors clustered with MEN1. Four of 5 MEN1-like sporadic PanNET subtypes had loss of heterozygosity at the MEN1 gene locus. Pathway analysis demonstrated subtype-specific pathway activation, comprising angiogenesis and immune response in VHL; neuronal development in MEN1; protein ubiquitination in the new MEN1/sporadic subtype; and cytokinesis and cilium/microtubule development in sporadic NFPanNETs. Among many genes, platelet-derived growth factor receptor β (PDGFRB), lymphoid enhancer-binding factor-1 (Lef-1), cyclin-dependent kinase 4 (CDK4), and CDK6 were upregulated in VHL or MEN1 NFPanNETs, providing potential subtype-specific treatment targets. CONCLUSIONS Distinct mRNA expression patterns were identified in sporadic-associated, VHL-associated, and MEN1-associated NFPanNETs. The current results uncover new pathways involved in NFPanNETs that are subtype-specific and provide potential new diagnostic or therapeutic targets based on tumor subtype. Cancer 2018;124:636-47. © 2017 American Cancer Society.

Context: Germline gain-of-function variants in the transcription factor GCM2 were found in 18% of kindreds with familial isolated hyperparathyroidism (FIHP). These variants [c.1136T>A (p.Leu379Gln) and c.1181A>C (p.Tyr394Ser)] were located in a 17-amino acid transcriptional inhibitory domain named C-terminal conserved inhibitory domain (CCID). Objective: We investigated the ethnicity of individuals with germline variants in the GCM2 CCID in our primary hyperparathyroidism (PHPT) patient samples and in the Genome Aggregation Database. Design: Ethnicity information was obtained from an in-house clinical database and genetic counseling. Sanger sequencing of blood DNA was used to determine the genotype of the GCM2 CCID region. Luciferase reporter assays were performed to determine the functional impact of GCM2 variants. Setting and Patients: National Institute of Diabetes and Digestive and Kidney Diseases endocrine clinic is a service that accepts PHPT referral patients. Results: The GCM2 p.Tyr394Ser variant was found in 41% [95% confidence interval (CI), 22% to 64%] of Ashkenazi Jewish (AJ) kindreds with FIHP and in 27% (95% CI, 17% to 40%) of AJ patients with sporadic PHPT. The p.Tyr394Ser variant was also found in sporadic PHPT patients of European ancestry, but at a lower prevalence. The p.Leu379Gln variant was found in 8% (95% CI, 1% to 26%) of European kindreds with FIHP and 0.5% (95% CI, 0% to 3.0%) of sporadic PHPT cases of European ancestry. The sporadic PHPT patients with GCM2-activating variants often had multigland involvement or postoperative recurrent or persistent disease. Conclusions: Specific GCM2-activating variants enriched among various ethnic backgrounds could contribute to a large number of cases with FIHP or sporadic PHPT., Specific GCM2 activating variants enriched in various ethnic backgrounds could contribute to a large number of cases with familial isolated hyperparathyroidism or sporadic primary hyperparathyroidism.

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant condition characterized by parathyroid, anterior pituitary and enteropancreatic endocrine cell tumors. Neuroendocrine tumors occur in approximately in 5–15% of MEN1 patients. Very few cases of ovarian NETs have been reported in association with clinical MEN1 and without genetic testing confirmation. Thirty-three-year-old woman with MEN1 was found to have right adnexal mass on computed tomography (CT). Attempt at laparoscopic removal was unsuccessful, and mass was removed via a minilaparotomy in piecemeal fashion. Pathology showed ovarian NET arising from a teratoma. Four years later, patient presented with recurrence involving the pelvis and anterior abdominal wall. She was treated with debulking surgery and somatostatin analogs (SSAs). Targeted DNA sequencing analysis on the primary adnexal mass as well as the recurrent abdominal wall tumor confirmed loss of heterozygosity (LOH) at the MEN1 gene locus. This case represents to our knowledge, the first genetically confirmed case of ovarian NET arising by a MEN1 mechanism in a patient with MEN1. Extreme caution should be exercised during surgery as failure to remove an ovarian NET en masse can result in peritoneal seeding and recurrence. For patients with advanced ovarian NETs, systemic therapy options include SSAs, peptide receptor radioligand therapy (PRRT) and novel agents targeting mammalian target of rapamycin (mTOR) and vascular endothelial growth factor (VEGF). Learning points: Ovarian NET can arise from a MEN1 mechanism, and any adnexal mass in a MEN1 patient can be considered as a possible malignant NET. Given the rarity of this disease, limited data are available on prognostication and treatment. Management strategies are extrapolated from evidence available in NETs from primaries of other origins. Care should be exercised to remove ovarian NETs en bloc as failure to do so may result in peritoneal seeding and recurrence. Treatment options for advanced disease include debulking surgery, SSAs, TKIs, mTOR inhibitors, PRRT and chemotherapy. Background Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant condition, caused by a germline mutation in the MEN1 gene, leading to the development of tumors of the parathyroid glands, anterior pituitary and enteropancreatic endocrine cells. NETs are well-differentiated neuroendocrine neoplasms originating from enterochromaffin cells typically disseminated throughout the gastrointestinal and bronchopulmonary system and can also occur in patients with MEN1 (1). NETs are traditionally classified based upon the embryologic site of origin (foregut, midgut or hindgut), morphologic pattern and silver stain affinity differences (insular, trabecular, mucinous, strumal or mixed). Newer classification systems have been developed to emphasize the considerable clinical and histopathologic variability of NETs found within each embryologic site of origin. The most recent WHO 2017 classification differentiates pancreatic NETs into three grades (low, intermediate and high), and other gastrointestinal NETs into two grades (low and intermediate) on the basis of mitotic count per high power field and proliferative index (Ki-67) (2). The majority of MEN1 syndrome-associated NETs are of foregut origin (thymus 24%, bronchus 27%, stomach 3% and duodenum 14%). Ovarian NETs are rare, comprising 0.1% of all ovarian neoplasms, and very few cases of primary ovarian NET in patients with MEN1 syndrome have been reported in the literature (1, 3). However, none of the cases reported confirmed the origin of tumor by a MEN1 mechanism (loss of heterozygosity at MEN1 locus) (1, 4). Given their rarity, data regarding treatment of ovarian NETs are limited. Here, we present a case of primary ovarian NET arising from a teratoma in a patient with MEN1 with targeted DNA sequencing of the tumor. A brief discussion about challenges and recent advances in the management of primary ovarian NETs follows.

Background: Further characterization of insulinomas from MEN1 patients versus sporadic cases may help elucidate pathophysiological differences and improve future diagnostic algorithms. Methods A retrospective analysis of all patients with insulinoma were included (MEN1 between 1971-2019; sporadic between 1997-2019). Demographic, clinical, laboratory results including a supervised fast, imaging and intra-arterial calcium stimulation (CaStim) data were retrieved when available. Categorical and continuous variables were compared using Fisher’s exact test and Mann-Whitney U-test, respectively. Results One hundred and thirteen patients were identified with insulinoma (69 women, median 44 years, range 13-78 years); of these, 27 patients had MEN1 (11 women, median 37 years, range 18-64 years). Patients with MEN1-related insulinomas sustained a significantly longer duration of the fast and had larger surgically resected tumors (29.73±15.32 vs 15.4±10.8 hours, p

Patients with the multiple endocrine neoplasia 1 (MEN1) syndrome develop various tumors during their lifetime. One of the rare manifestations observed in MEN1 patients is thymic neuroendocrine tumor (Th-NET) or thymic carcinoid, which is a major cause of death due to its aggressive nature, frequent recurrence, and lack of effective treatment. The goal of this study was to analyze the clinical presentation and outcome of Th-NETs in MEN1 patients at our institution and to investigate the correlation between genotype and phenotype. We evaluated the clinical characteristics of MEN1 patients with Th-NETs from a cohort of 350 patients with a MEN1 germline mutation and identified 13 patients (3.7%) with Th-NETs: 11 with thymic carcinoid, 1 with a thymoma demonstrating a neuroendocrine phenotype, and 1 with a non-neuroendocrine thymoma. Thymic carcinoid occurred exclusively in men and was the first tumor identified in 2 of the patients, while the 2 patients with thymoma were both females. Median age of diagnosis for Th-NETs was 43 years (range: 29-65 years). Mean tumor largest diameter was 7.18 cm (range: 2.5-15 cm). ACTH production was not detected in any of the thymic carcinoid cases. Seven patients died, 4 of them are still followed, and 2 of them were lost to follow-up. Th-NETs recurred following surgical resection in 7 patients. Family history of thymic carcinoid was identified in 6 patients. Smoking history was found in 6 patients. MEN1-associated tumors in our cohort included parathyroid adenoma (n=13), pancreatic NET (n=11), pituitary adenoma (n=8), Zollinger-Ellison syndrome (n=7), and lung carcinoid (n=1). In archived tumor samples obtained from 11 patients, chromogranin-A and synaptophysin immunohistochemistry confirmed the neuroendocrine phenotype in thymic carcinoids and showed neuroendocrine differentiation in one of the thymomas. Tumor grade analysis was performed using Ki-67 staining. Genomic DNA was isolated from peripheral blood leukocytes and the following MEN1 germline heterozygous mutations were identified: 8 frameshift, 3 nonsense, 1 in-frame deletion, and 1 missense mutation (found in a thymoma sample). The mutations were scattered throughout the entire MEN1 coding region without specific clustering. Moreover, the only genotype-phenotype correlation observed was a preponderance of protein truncating mutations (frameshift and nonsense) in the Th-NET cohort. Th-NETs are uncommon in MEN1 syndrome. Our Th-NET cohort showed a male predominance. MEN1 mutations in the Th-NET patients did not show any specific clustering, but a preponderance of protein truncating mutations was observed in the MEN1 gene. Further analysis of Th-NET samples for genetic alterations and gene expression profiles will help to uncover the yet to be determined modifying factors in the pathophysiology of Th-NETs.

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

BACKGROUND: Gastric neuroendocrine tumors (carcinoid) associated with Zollinger Ellison Syndrome (ZES) induced hypergastrinemia in Multiple Endocrine Neoplasia type 1 (MEN1) occur in 15-50% of patients and are generally thought to be benign. Here we present a case of metastatic grade 3 gastric neuroendocrine tumor in MEN1. CASE: A 41-year male with history of MEN1 syndrome manifested by hyperparathyroidism, pancreatic neuroendocrine tumors, and Zollinger-Ellison Syndrome had been followed for 10 years. The patient had undergone yearly surveillance including CT, MRI, upper GI endoscopy (EGD) and 68Ga-DOTATATE, which had identified multiple small foci in the pancreas and duodenum. However, only MRI revealed a T2 hypointense 2.6 cm mildly enhancing mass along the lesser curvature of the stomach that was not visible on CT, MRI, EGD or 68Ga-DOTATATE within the 2 years prior. Gastrin levels remained 20% and mitotic count >20 per 10 high powered fields. At the time of diagnosis, this lesion was histologically classified as well to moderately differentiated, high grade neuroendocrine carcinoma (Grade 3), large cell type. Loss of heterozygosity for the MEN1 gene at 11q13 was confirmed in the tumor. Monitoring with serial scans demonstrated right hepatic lobe metastasis by 1-year post-surgery. CONCLUSION: Previous reports of MEN1/ZES gastric carcinoid are associated with high gastrin levels, long disease duration, and are typically grade 1 or 2[i]. Special attention to identification of gastric mucosal nodules with well-controlled ZES is required as these lesions may rarely become malignant. Endnotes i Berna MJ, et al. A prospective study of gastric carcinoids and enterochromaffin-like cell changes in multiple endocrine neoplasia type 1 and Zollinger-Ellison syndrome: identification of risk factors. JCEM. 2008; 93(5):1582-91.

Introduction MEN1 is an autosomal dominant condition characterized by parathyroid, anterior pituitary and enteropancreatic endocrine cell tumors. Carcinoids occur in 5-15% patients, majority of which are of foregut origin (thymus, bronchus, stomach and duodenum). Only 1 case of ovarian carcinoid has been reported in association with MEN1, and was not confirmed with genetic testing. Case report A 33-year-old female with a macroprolactinoma and primary hyperparathyroidism was referred to us with a presumptive diagnosis of MEN1. Genetic testing showed a heterozygous germline mutation in the MEN1 gene, c.219_220delCG (frameshift leading to premature protein truncation). She had no family history consistent with MEN1. EGD showed two submucosal nodules in the duodenum with confirmed histology of gastrinomas. CT demonstrated 8.7 x 7.7 cm right adnexal mass containing foci of soft tissue density and calcification. Laparoscopic resection was attempted but the mass was too large to be delivered en-bloc. Operative approach was changed to a minilaparotomy and the mass was delivered in a piecemeal fashion. Pathology demonstrated a benign dermoid cyst with neuroendocrine tumor consistent with carcinoid extending into peri-ovarian tissues. 4 years later, she presented with a lower abdominal palpable mass. CT showed an irregular, avidly enhancing 11.7 x 8.7 cm pelvic mass, extending through the anterior abdominal wall into the subcutaneous fat with satellite lesions within the anterior subcutaneous abdomen. The CT abnormalities corresponded to abnormally elevated In-111 pentetreotide uptake. Biopsy of one of the subcutaneous lesions showed metastatic neuroendocrine neoplasm with Ki67 index of 2%. Targeted genetic analysis for the patient’s MEN1 mutation using DNA samples isolated from the primary adnexal mass as well as the recurrent abdominal wall tumor demonstrated predominantly mutant sequence in both specimens, confirming LOH at the MEN1 gene locus. 5 months later, the patient presented with obstructive uropathy from nodal metastases. She underwent debulking surgery via exploratory laparotomy, panniculectomy, resection of metastatic abdominal wall tumors and abdominal wall reconstruction. Post operatively, FDG-PET scan showed few scattered disease foci. She was commenced on monthly octreotide injections. Conclusions This case represents to our knowledge, the first genetically confirmed case of ovarian carcinoid arising by a MEN1 mechanism. Ovarian carcinoid should be considered as a differential in MEN1 patients with adnexal mass. Extreme caution should be exercised during surgical resection, as failure to remove an ovarian carcinoid en masse can result in peritoneal seeding and recurrence. For patients with advanced disease, systemic therapy options include somatostatin receptor analogs, peptide receptor radioligand therapy, and novel agents targeting mTOR and VEGF. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

Background: Multiple Endocrine Neoplasia Type 1 (MEN1) is a rare inherited autosomal dominant disease predisposing patients to endocrine tumors. MEN1 can be genetically diagnosed at an early age. Patients are prone to develop benign parathyroid tumors then multifocal duodenopancreatic neuroendocrine tumors (dpNETs), which have a penetrance of >80% by age 80. Although they can be identified at an early stage, preventive measures do not exist, and one fifth of patients develop distant metastases, which is the most significant cause of mortality. Currently, no biomarkers can reliably predict which patients with MEN1-related dpNETs are at high risk of developing metastatic disease. Polyamines are naturally occurring polycationic alkylamines that have been implicated to play functional roles in promoting neoplastic transformation and growth. We have previously demonstrated a plasma polyamine signature that associates with pancreatic cancer development and that also offers value for predicting future distant metastasis in patients with triple-negative breast cancer. We hypothesized that such a plasma polyamine signature may similarly associate with disease progression in subjects with MEN1-related dpNET. Methods: As part of an international collaboration, we measured plasma polyamine levels using mass spectrometry from 14 MEN1 patients with distant metastatic dpNET (cases), 28 MEN1 patients with indolent dpNETs without distant metastases (control-1), and 14 MEN1 patients without dpNETs (control-2). Five circulating plasma polyamines were quantified in this initial test set. A combination rule was developed using logistic regression models. Findings were validated in an independent set of plasma from 6 cases and 22 controls (n=13 control-1 and n=9 control-2). Results: Area under the Receiver Operating Characteristic Curve (AUC) of individual polyamines delineating cases from controls ranged from 0.50-0.75 in the test set. A polyamine signature consisting of 3 polyamines developed in the test set yielded an AUC of 0.84 (95% CI: 0.63-1.00) with 67% sensitivity at 95% specificity in the validation set for distinguishing cases from controls. The predictive performance of the polyamine signature for distinguishing cases from MEN1 patients with indolent dpNETS without distant metastasis or MEN1 patients without dpNETS in the validation set was 0.79 (95% CI: 0.53-1.00) and 0.91 (95% CI: 0.75-1.00) with respective resultant sensitivity at 95% specificity of 50% and 67%. Conclusion: Our findings reveal a plasma polyamine signature associated with disease progression in subjects with MEN1-related dpNETs. This polyamine signature may provide a potential breakthrough for predicting progression and distant metastasis in MEN1 patients. Further prospective studies are warranted.

Multiple endocrine neoplasia (MEN) type 1 (MEN1) and 2 (MEN2) rarely co-exist in one case. Here we report a patient with features of both syndromes. The patient presented with typical MEN1 features plus pheochromocytoma and thickened corneal nerves. She had a germline 1132delG frameshift mutation in MEN1, no mutation in CDKN1B (p27) and no RET mutation, but had both RET polymorphisms Gly691Ser and Arg982Cys. This is the first case report of a combination of typical clinical findings of MEN1 harboring a germline MEN1 mutation and the MEN2-like phenotype with negative full RET gene analysis of pathogenic variants. Possible explanations include a previously unrecognized phenotype–genotype association or the influence of potential phenotypic modifying RET variants. Furthermore, the combination observed in this patient may point to a single molecular pathway, and supports the possibility of as yet unrecognized connections between the molecular pathways for MEN1/menin protein and MEN2/RET protein.

Genetic and epigenetic alterations impact human health and disease. Genetic information encoded in the DNA is faithfully passed on to daughter cells upon mitotic cell division and to the next generation through the germline. There are more than 200 different cell types in the human body each with its own distinct phenotype that is always maintained and also retained upon subsequent cell division. Epigenetic control is responsible for the translation of genotype to phenotype by establishing and maintaining specialized gene expression programs through changes in chromatin without altering the underlying DNA sequence. Epigenetic control also elicits allele-specific gene expression that is associated with the process of imprinting and X-chromosome inactivation. This chapter presents a general background of epigenetic control mechanisms and the contribution of epigenetics to human disease.

The long noncoding RNA (lncRNA) MEG3 is significantly downregulated in pancreatic neuroendocrine tumors (PNETs). MEG3 loss corresponds with aberrant upregulation of the oncogenic hepatocyte growth factor (HGF) receptor c-MET in PNETs. Meg3 overexpression in a mouse insulin-secreting PNET cell line, MIN6, downregulates c-Met expression. However, the molecular mechanism by which MEG3 regulates c-MET is not known. Using ch romatin i solation by R NA p urification and seq uencing (ChIRP-Seq), we identified Meg3 binding to unique genomic regions in and around the c-Met gene. In the absence of Meg3, these c-Met regions displayed distinctive enhancer-signature histone modifications. Furthermore, Meg3 relied on functional enhancer of zeste homolog 2 (EZH2), a component of polycomb repressive complex 2 (PRC2), to inhibit c-Met expression. Another mechanism of lncRNA-mediated regulation of gene expression utilized triplex-forming GA-GT rich sequences. Transfection of such motifs from Meg3 RNA, termed triplex-forming oligonucleotides (TFOs), in MIN6 cells suppressed c-Met expression and enhanced cell proliferation, perhaps by modulating other targets. This study comprehensively establishes epigenetic mechanisms underlying Meg3 control of c-Met and the oncogenic consequences of Meg3 loss or c-Met gain. These findings have clinical relevance for targeting c-MET in PNETs. There is also the potential for pancreatic islet β-cell expansion through c-MET regulation to ameliorate β-cell loss in diabetes.