18F-Radiolabeling and Preliminary Evaluation of a HSP90 ligand.

PURPOSE: With the ambition of improving the management of pancreatic neuroendocrine tumors (P-NETs), we developed and preliminary validated a novel fluorine-18 labelled HSP90 ligand. METHODS: A precursor containing methoxymethyl ethers protecting groups and a tosyl as leaving group was synthesized. The target compound was labeled with nucleophilic 18F-fluoride and the protecting groups was subsequently removed with hydrochloric acid before purification. In vitro cell- and frozen section autoradiography and in vivo animal studies were performed. RESULTS: The precursor was successfully synthesized and utilized in the 18F-radiolabeling giving 0.5-1.0 GBq of pure product with a synthesis time of 70 min. In vitro experiments indicated a high specific binding, but in vivo studies showed no tumor uptake due to fast hepatobiliary metabolism and excretion. CONCLUSIONS: Despite the unfavorable in vivo properties of the tracer, the promising results from in vitro autoradiography experiments in frozen sections of P-NETs from surgical resection encourage us to continue the project aiming the improvement of in vivo properties of the tracer.

Mitotane effects in a H295R xenograft model of adjuvant treatment of adrenocortical cancer.

Adrenocortical cancer is one of the most aggressive endocrine malignancies. Growth through the capsule or accidental release of cancer cells during surgery frequently results in metastatic disease. We investigated the antitumoral effect of 2 adrenocorticolytic compounds, O, P'-DDD and MeSO2-DDE, in the adrenocortical cell line H295R both in vitro and as a xenograft model in vivo. H295R cells were injected s. c. in nude mice. O, P'-DDD, MeSO2-DDE, or oil (control) was administered i. p., either simultaneously with cell injection at day 0 (mimicking adjuvant treatment), or at day 48 (established tumors). Accumulation of PET tracers [ (11)C]methionine (MET), [ (11)C] metomidate (MTO), 2-deoxy-2-[ (18)F]fluoro-d-glucose (FDG), and [ (18)F]-l-tyrosine (FLT) in the aggregates were assessed +/- drug treatment in vitro. Tumor growth was significantly inhibited when O, P'-DDD was given at the same time as injection of tumor cells. No significant growth inhibition was observed after treatment with O, P'-DDD at day 48. A significant reduction in FLT uptake and an increased FDG uptake, compared to control, were observed following treatment with 15 microM O, P'-DDD (p<0.01) in vitro. MeSO2-DDE (15 microM) treatment gave rise to a reduced MET and an increased FLT uptake (p<0.01). Both compounds reduced the uptake of MTO compared to control (p<0.01). Treatment with O, P'-DDD simultaneously to inoculation of H295R cells in mice, imitating release of cells during surgery, gave a markedly better effect than treatment of established H295R tumors. We suggest that FLT may be a potential PET biomarker when assessing adrenocortical cancer treatment with O,P'-DDD. Further studies in humans are needed to investigate this.

Advances in adrenal tumors 2018.

This review aims to provide clinicians and researchers with a condensed update on the most important studies in the field during 2017. We present the academic output measured by active clinical trials and peer-reviewed published manuscripts. The most important and contributory manuscripts were summarized for each diagnostic entity, with a particular focus on manuscripts that describe translational research that have the potential to improve clinical care. Finally, we highlight the importance of collaborations in adrenal tumor research, which allowed for these recent advances and provide structures for future success in this scientific field.

DNA copy number status is a powerful predictor of poor survival in endocrine pancreatic tumor patients.

The clinical behavior of endocrine pancreatic tumors (EPTs) is difficult to predict in the absence of metastases or invasion to adjacent organs. Several markers have been indicated as potential predictors of metastatic disease, such as tumor size > or =2 cm, Ki67 proliferative index > or =2%, cytokeratin (CK) 19 status, and recently in insulinomas, chromosomal instability (CIN). The goal of this study was to evaluate the value of these markers, and in particular of the CIN, to predict tumor recurrence or progression and tumor-specific death, using a series of 47 insulinomas and 24 non-insulinoma EPTs. From these EPT cases, a genomic profile has been generated and follow-up data have been obtained. The proliferative index has been determined in 68 tumors and a CK19 expression pattern in 50 tumors. Results are statistically analyzed using Kaplan-Meier plots and the log-rank statistic. General CIN, as well as specific chromosomal alterations such as 3p and 6q loss and 12q gain, turned out to be the most powerful indicators for poor tumor-free survival (P< or =0.0004) and tumor-specific death (P< or =0.0113) in insulinomas. The CIN, chromosome 7q gain, and a proliferative index > or =2% were reliable in predicting a poor tumor-free survival in non-insulinoma EPTs (P< or =0.0181, whereas CK19 expression was the most optimal predictor of tumor-specific death in these tumors. In conclusion, DNA copy number status is the most sensitive and efficient marker of adverse clinical outcome in insulinomas and of potential interest in non-insulinoma EPTs. As a consequence, this marker should be considered as a prognosticator to improve clinical diagnosis, most practically as a simple multi-target test.

Molecular parameters associated with insulinoma progression: chromosomal instability versus p53 and CK19 status.

Insulinomas represent the predominant syndromic subtype of endocrine pancreatic tumors (EPTs). Their metastatic potential cannot be predicted reliably using histopathological criteria. In the past few years, several attempts have been made to identify prognostic markers, among them TP53 mutations and immunostaining of p53 and recently cytokeratin 19 (CK19). In a previous study using conventional comparative genomic hybridization (CGH) we have shown that chromosomal instability (CIN) is associated with metastatic disease in insulinomas. It was our aim to evaluate these potential parameters in a single study. For the determination of CIN, we applied CGH to microarrays because it allows a high-resolution detection of DNA copy number changes in comparison with conventional CGH as well as the analysis of chromosomal regions close to the centromeres and telomeres, and at 1pter-->p32, 16p, 19 and 22. These regions are usually excluded from conventional CGH analysis, because they may show DNA gains in negative control hybridizations. Array CGH analysis of 30 insulinomas (15 tumors of benign, eight tumors of uncertain and seven tumors of malignant behavior) revealed that >or=20 chromosomal alterations and >or=6 telomeric losses were the best predictors of malignant progression. A subset of 22 insulinomas was further investigated for TP53 exon 5-8 gene mutations, and p53 and CK19 expression. Only one malignant tumor was shown to harbor an arginine 273 serine mutation and immunopositivity for p53. CK19 immunopositivity was detected in three malignant tumors and one tumor with uncertain behavior. In conclusion, our results indicate that CIN as well as telomeric loss are very powerful indicators for malignant progression in sporadic insulinomas. Our data do not support a critical role for p53 and CK19 as molecular parameters for this purpose.

Different splice variants of CD44 are expressed in gastrinomas but not in other subtypes of endocrine pancreatic tumors.

Endocrine pancreatic tumors are neuroendocrine neoplasms with malignant potential and give rise to varied clinical syndromes due to excessive secretion of multiple hormones. In this study 22 endocrine pancreatic tumors and 11 carcinoid tumors were examined for the expression of CD44 using a monoclonal antibody. CD44 gene activity of 11 endocrine pancreatic tumor tissues and five carcinoid tumor tissues was also studied by amplifying messenger RNA with the polymerase chain reaction followed by electrophoresis and blot hybridization. Strong immunoreactivity was detected on all gastrinomas examined (P < 0.001), and in two non-functioning endocrine pancreatic tumors. Such immunoreactivity was not observed in other subtypes of endocrine pancreatic tumors. In the normal human pancreas, the acinar portion and ductal epithelial cells stained strongly positive but pancreatic islet cells did not show any significant immunostaining. Furthermore, in endocrine pancreatic tumors with metastatic disease, CD44-positive tumors had a tendency to metastasize to lymph nodes (P = 0.005), as compared with CD44-negative tumors which were locally invasive or metastasized to the liver. Although, in this limited material and short follow-up, we were not able to show any statistical significance, patients with CD44-negative endocrine pancreatic tumors had prolonged survival time compared with patients with CD44-positive tumors (73% versus 59% at 5 years; P = 0.7). Of 10 carcinoid tumors examined, all three foregut carcinoids and one midgut carcinoid stained strongly positive, whereas all other midgut carcinoids were negative. Analysis of CD44 splice variants showed that in all five gastrinomas there was overproduction of alternatively spliced larger molecular variants as compared with other types of endocrine pancreatic tumors and carcinoid tumors. The band pattern from one case of carcinoid tumor with a fulminant clinical course was similar to that of gastrinomas, whereas other carcinoid tumors expressed the epithelial form of CD44. The earlier identified splice variants which confer metastatic behavior on a pancreatic tumor cell line were not expressed in neuroendocrine tumors. Our data indicate that CD44 expression in endocrine pancreatic tumors correlates with the ability to give rise to lymph node metastases and may play a vital role in determining the fate of metastasizing cells. Moreover, because gastrin is not detectable in the normal human pancreas, the pancreatic ductal cell positivity for CD44 strengthened the ductal origin concept of gastrinomas. The band pattern of CD44 splice variants suggests that the previously described splice variants conferring metastatic behavior do not accompany metastatic activity of neuroendocrine tumors.

Mutation of the multiple endocrine neoplasia type 1 gene in nonfamilial, malignant tumors of the endocrine pancreas.

Endocrine pancreatic tumors are rare neoplasms that occur sporadically or as part of a multiple endocrine neoplasia type 1 (MEN1) syndrome. Germ-line mutations of the MEN1 gene, located at 11q13, have been demonstrated in MEN1 kindreds, and loss of heterozygosity (LOH) on 11q13 together with somatic MEN1 mutations have been detected in 20% of nonfamilial parathyroid tumors. Here, we examine 11 non-MEN1 malignant tumors of the endocrine pancreas, 9 nonfunctioning tumors, and 2 glucagonomas. LOH of at least one informative locus on 11q13 was found in 70% of the tumors. Three tumors displayed somatic mutations of the MEN1 gene together with LOH on 11q13, whereas the corresponding germ-line DNA was normal. These findings support the hypothesis that MEN1 gene mutations contribute to the tumorigenesis of nonfamilial, malignant endocrine pancreatic tumors.

Molecular cloning and characterization of a cDNA encoding mouse phospholipase C-beta3.

A cDNA encoding mouse PLC-beta3 (mPLC-beta3) was identified by screening a mouse kidney cDNA library and using the rapid amplification of cDNA ends (RACE) method. The predicted open reading frame was 3705 bp in length. The deduced 1235 amino acid (aa) sequence shares 95.3% and 92% homology with the sequences of rat and human PLC-beta3, respectively. The corresponding mRNA is highly expressed in kidney, skeletal muscle, liver, lung, heart and brain. In spleen, mPLC-beta3 mRNA was not detectable, which is in contrast to humans where there is a distinct expression. Using ultrastructural immunocytochemistry, mPLC-beta3 expression was detected in the heterochromatin of the nucleus in mouse brain neurons. The observation of PLC-beta3 nuclear localization suggests that PLC-beta3 may have intranuclear functions.

Menin represses JunD-activated transcription by a histone deacetylase-dependent mechanism.

Recently the multiple endocrine neoplasia type 1 (MEN-1) tumor suppressor gene was cloned. MEN-1 encodes a nuclear protein, called menin, of hitherto unknown function. In order to investigate the biological function of menin we employed the yeast two-hybrid system to identify menin-interacting proteins. Here we report that menin functions as a transcriptional repressor through interaction with the transcription factor JunD. The interaction is mediated via the N-terminal transcription activation domain of JunD, and the C-terminal part of menin. In transient co-transfection experiments, expression of menin leads to specific repression of JunD transcriptional activity, which is dependent on the integrity of the menin C-terminal region. C-Terminal truncations of the protein not only abolish repression, but increase JunD transcriptional activity, implying the existence of a functional domain separate from the JunD-binding region. Menin-mediated repression is relieved by the histone deacetylase inhibitor trichostatin A, indicating that deacetylation of histones is an essential component of this repression mechanism, as has recently been demonstrated for the retinoblastoma protein. Missense, in-frame deletions, frameshift and nonsense mutations lead to inactivation of menin or possibly to truncated proteins. This would result in loss of repression of menin/JunD target genes, as well as non-target genes through indirect mechanisms, deregulation of cellular growth control and endocrine tumorigenesis.

Whole-body (11)C-5-hydroxytryptophan positron emission tomography as a universal imaging technique for neuroendocrine tumors: comparison with somatostatin receptor scintigraphy and computed tomography.

Neuroendocrine tumors (NETs) can be small and situated almost anywhere throughout the body. Our objective was to investigate whether whole-body (WB) positron emission tomography (PET) with (11)C-5-hydroxytryptophan (5-HTP) can be used as a universal imaging technique for NETs and to compare this technique with established imaging methods. Forty-two consecutive patients with evidence of NET and a detected lesion on any conventional imaging (six bronchial, two foregut, 16 midgut, and two thymic carcinoids; one ectopic Cushing's syndrome; four gastrinomas; one insulinoma; six nonfunctioning endocrine pancreatic tumors; one gastric carcinoid, one paraganglioma; and two endocrine-differentiated pancreatic carcinomas) were studied. The WB-(11)C-5-HTP-PET examinations were compared with WB-computed tomography (CT) and somatostatin receptor scintigraphy (SRS). Tumor lesions were imaged with PET in 95% of the patients. In 58% of the patients, PET could detect more lesions than SRS and CT and equal numbers in 34%, whereas in three cases, SRS or CT showed more lesions. In 84% (16 of 19 patients), PET could visualize the primary tumor compared with 47 and 42% for SRS and CT, respectively. The surgically removed PET-positive primary tumor sizes were 6-30 mm. To conclude, this study indicates that WB-(11)C-5-HTP-PET can be used as a universal imaging method for detection of NETs. This study also shows that WB-(11)C-HTP-PET is sensitive in imaging small NET lesions, such as primary tumors, and can in a majority of cases image significantly more tumor lesions than SRS and CT.

Definition of the Minimal MEN1 Candidate Area Based on a 5-Mb Integrated Map of Proximal 11q13

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder with a high penetrance characterized by tumors of the parathyroid glands, the endocrine pancreas, and the anterior pituitary. The MEN1 gene, a putative tumor suppressor gene, has been mapped to a 3- to 8-cM region in chromosome 11q13 but it remains elusive as yet. We have combined the efforts and resources from four laboratories to form the European Consortium on MEN1 with the aims of establishing the genetic and the physical maps of 11q13 and of further narrowing the MEN1 region. A 5-Mb integrated map of the region was established by fluorescence in situ hybridization on both metaphase chromosomes and DNA fibers, by hybridization to DNA from somatic cell hybrids containing various parts of human chromosome 11, by long-range restriction mapping, and by characterization of YACs and cosmids. Polymorphic markers were positioned and ordered by physical mapping and genetic linkage in 86 MEN1 families with 452 affected individuals. Two critical recombinants identified in two affected cases placed the MEN1 gene in an approximately 2-Mb region around PYGM, flanked by D11S1883 and D11S449.

Subcellular distribution of phospholipase C isoforms in rodent pancreas and gastric mucosa.

Phosphoinositide-specific phospholipase C (PLC) has been implicated as a participant in cell proliferation as well as enzyme and hormone secretion. Defining the subcellular distribution of PLC isoforms would possibly contribute to further understanding of their function. We investigated the intracellular distribution of four PLCs (beta1, beta2, beta3, and gamma1) in mouse pancreatic cells as well as mouse and rat gastric mucosa cells by ultrastructural immunocytochemistry. In pancreatic acinar cells, PLCbeta1 and PLCgamma1 were demonstrated in the zymogen granules while PLCbeta2 was present in the granulae as well as the endoplasmic reticulum (ER), and PLCbeta3 was prominent in the ER. In the endocrine pancreas, PLCbeta2 immunolabeling was expressed in the secretory granulae of alpha, beta, delta, and pancreatic polypeptide cells. PLCbeta3 showed a slight labeling in the nucleus and ER of all four pancreatic endocrine cell types while PLCgamma1 was prominent in alpha cell granulae. In the gastric mucosa cells, PLCbeta2 was highly expressed in the heterochromatin areas and in the ER of parietal, chief, mucous, and enterochromaffin-like cells. PLCbeta3 were expressed in a manner similar to PLCbeta2 in those cells; however, no immunoreaction was seen in the ER of parietal cell. PLCgamma1 was demonstrated in the chief cell granulae. One possible, although yet speculative, interpretation of our results is that the studied PLC isoforms may be involved in processing in pancreatic secretory granulae and that nuclear PLCbeta2 and PLCbeta3 signaling pathways may be operative in the cells of the gastric mucosa.

Multiple allelic deletions and intratumoral genetic heterogeneity in men1 pancreatic tumors.

Multiple endocrine neoplasia type 1 (MEN1) is an inherited syndrome with multiple tumors of the endocrine pancreas, the parathyroid, the pituitary, and other tissues. The MEN1 gene at 11q13 is homozygously mutated in the majority of MEN1 tumors. Here we present a genome-wide loss of heterozygosity (LOH) screening of 23 pancreatic lesions, one duodenal tumor, and one thymic carcinoid from 13 MEN1 patients. Multiple allelic deletions were found. Fractional allelic loss varied from 6-75%, mean 31%. All pancreatic tumors displayed LOH on chromosome 11, whereas the frequency of losses for chromosomes 3, 6, 8, 10, 18, and 21 was over 30%. Different lesions from individual patients had discrepant patterns of LOH. Intratumoral heterogeneity was revealed, with chromosome 6 and 11 deletions in most tumor cells, whereas other chromosomal loci were deleted in portions of the analyzed tumor. Chromosome 6 deletions were mainly found in lesions from patients with malignant features. Fractional allelic loss did not correlate to malignancy or to tumor size. Our findings indicate that MEN1 pancreatic tumors fail to maintain DNA integrity and demonstrate signs of chromosomal instability.

Prognostic markers in patients with typical bronchial carcinoid tumors.

Typical bronchial carcinoids are usually considered fairly benign tumors. Metastases do however occur, and up to 10% of the patients ultimately die from their disease. To identify prognostic markers, we immunostained 43 typical bronchial carcinoids with antibodies against 8 possibly relevant hormones, oncogenes, tumor suppressor genes, adhesion molecules, and proliferation markers. Altogether 12 patients (28%) had metastatic disease, of whom 10 had regional lymph node metastases at diagnosis. Distant metastases have occurred in 5 patients (12%); all of these have died from their disease. Patients with high expression of Ki-67 had shorter survival time (P < 0.01). None of the immunostained hormones correlated to distant metastases or shorter survival time, but gastrin-releasing peptide correlated to metastatic disease (P < 0.05). All patients who died had CD44-negative tumors (P < 0.001). Nuclear nm23 staining correlated to decreased risk for metastatic disease and distant metastases per se (P < 0.01). Bcl-2 and p53 were associated with increased risk for distant metastases (P < 0.05 and P < 0.01, respectively). We conclude that some patients with typical bronchial carcinoids die from their disease and that gastrin-releasing peptide, Bcl-2, and p53 may be of importance for the malignant transformation of the tumor. Moreover, CD44, nm23, and Ki-67 may give valuable prognostic information and help identify the patients at risk of disease-related death.

Plasma chromogranin A in patients with multiple endocrine neoplasia type 1.

Plasma chromogranin A (CgA) has been claimed to be a sensitive marker for neuroendocrine tumors, but its role in the early diagnosis of multiple endocrine neoplasia type 1 (MEN 1) pancreatic endocrine tumors has not been evaluated. We measured CgA in 36 patients with MEN 1, of whom 9 lacked pancreatic involvement, 20 had biochemical evidence of pancreatic endocrine tumors, and 7 displayed radiologically detectable pancreatic tumors. CgA was also analyzed in 25 patients with sporadic pancreatic endocrine tumors, 39 subjects with inflammatory bowel disease, 7 patients harboring nonendocrine pancreatic disease, and 19 healthy controls. Four of 9 of the MEN 1 patients without pancreatic involvement had elevated CgA. Furthermore, 60% with biochemically unequivocal tumors and all with a radiologically visible tumor showed elevations. All 25 patients with sporadic pancreatic endocrine tumor had increased CgA, as had 28% of patients with inflammatory bowel disease and 57% with nonendocrine pancreatic disease. Mean day to day CgA variation was 29% (range, 0-113%) in the neuroendocrine tumor patients and 21.0% (range, 0.0-47%, within reference range) among healthy controls. In summary, nonendocrine diseases may cause elevation of CgA, and its spontaneous variation can be considerable. Plasma chromogranin A is the most sensitive of the basal markers for neuroendocrine tumors, but cannot replace other established measures when screening for early pancreatic involvement in MEN 1.

A standardized meal stimulation test of the endocrine pancreas for early detection of pancreatic endocrine tumors in multiple endocrine neoplasia type 1 syndrome: five years experience.

Forty-nine members of 6 families with multiple endocrine neoplasia type 1 (MEN 1) were investigated with a standardized meal stimulation test to detect the presence of pancreatic endocrine tumors. Fifteen age-matched subjects and 4 patients with primary hyperparathyroidism also were studied. Serum pancreatic polypeptide (PP), gastrin, and insulin as well as plasma glucagon and somatostatin concentrations were determined before and during the test meal. Patients with demonstrable pancreatic endocrine tumors had significantly increased mean basal and peak serum PP (P less than 0.001) and gastrin (P less than 0.001) responses to the meal compared with healthy family members and normal subjects. Seven of 12 MEN 1 patients with parathyroid and pituitary disease but no demonstrable pancreatic endocrine tumors had exaggerated PP and/or gastrin responses to the meal; 4 of them developed pancreatic endocrine tumors, detected by abdominal computerized tomography, 0.5-4 yr later. None of the healthy members of the MEN 1 families or the patients with primary hyperparathyroidism had responses different from those of the normal subjects. Our experience with the meal stimulation test indicates that an elevated basal or exaggerated serum PP and/or gastrin response is an earlier sign of pancreatic involvement in the MEN 1 trait than is abdominal computerized tomography.

Multiple endocrine neoplasia type 1: a 10-year prospective screening study in four kindreds.

A total of 80 individuals in 4 kindreds with multiple endocrine neoplasia type 1 (MEN 1) have been subjected to repeated biochemical screening during a 10-yr period with the principal aim being to analyze characteristics of the developing pancreatic lesion. Age at presentation of the MEN 1 trait averaged 18 yr in 7 previously unaffected individuals, and this effect of the screening procedure represented a lowering by almost 2 decades. Pancreatic endocrine involvement was recognized at a mean age of 25 yr and constituted the presenting lesion in a majority of the patients. A standardized meal test and basal values of serum pancreatic polypeptide, insulin, proinsulin, and gastrin were the most efficient markers for the pancreatic lesion and preceded signs of pancreatic tumors upon radiological examinations by a mean of 3.5 yr. A 75% penetrance of the islet cell disease and 90% for primary hyperparathyroidism within the affected individuals equalled the prevalences reported in autopsy studies. Two of the kindreds showed signs of intrafamilial homogeneity with respect to the profile of peptide excess (P less than 0.05) and considerable discrepancy in the malignant potential of the pancreatic lesions. The results of early detection and surgical intervention of the pancreatic tumors in MEN 1 suggested an impact on morbidity, while any effect on the mortality of these individuals remains to be clarified.

Clinical and genetic features of adrenocortical lesions in multiple endocrine neoplasia type 1.

In multiple endocrine neoplasia type 1 (MEN-1), benign enlargement of the adrenal cortex has been found in about one third of necropsy cases. To elucidate the clinical and genetic characteristics of the MEN-1 adrenal lesion, we have investigated 33 MEN-1 patients. Twelve individuals (37%) demonstrated adrenal enlargement, which was bilateral in 7 of them. Histopathology revealed diffuse and nodular cortical hyperplasia, adenomas, and a single case of adrenocortical carcinoma. The apparently benign adrenal enlargements were not associated with presently ascertainable biochemical disturbances in the hypothalamic-pituitary-adrenocortical axis, and they were without radiological signs of progression during follow-up. The individual developing unilateral adrenocortical carcinoma showed rapid adrenal expansion, feminization, and an abnormal urinary steroid profile after 4 yr of observation for bilateral minor adrenal enlargements. Pancreatic endocrine tumors were significantly overrepresented and present in all MEN-1 individuals with adrenal involvement. In agreement with findings in sporadic cases, the MEN-1 adrenocortical carcinoma genome showed loss of constitutional heterozygosity for alleles at 17p, 13q, 11p, and 11q. The benign adrenal lesions retained heterozygosity for the MEN-1 locus at chromosome 11 q 13. Despite its prevalence and malignant potential, the pituitary-independent adrenocortical proliferation does not appear to be a primary lesion in MEN-1, but might represent a secondary phenomenon, perhaps related to the pancreatic endocrine tumor.

Parathyroid MEN1 gene mutations in relation to clinical characteristics of nonfamilial primary hyperparathyroidism.

Biochemical signs and severity of symptoms of primary hyperparathyroidism (pHPT) differ among patients, and little is known of any coupling of clinical characteristics of nonfamilial pHPT to genetic abnormalities in the parathyroid tumors. Mutations in the recently identified MEN1 gene at chromosome 11q13 have been found in parathyroid tumors of nonfamilial pHPT. Using microsatellite analysis for loss of heterozygosity (LOH) at 11q13 and DNA sequencing of coding exons, the MEN1 gene was studied in 49 parathyroid lesions of patients with divergent symptoms, operative findings, histopathological diagnosis, and biochemical signs of nonfamilial pHPT. Allelic loss at 11q13 was detected in 13 tumors, and 6 of them demonstrated previously unrecognized somatic missense and frameshift deletion mutations of the MEN1 gene. Many of the detected mutations would most likely result in a nonfunctional menin protein, consistent with a tumor suppressor mechanism. Clinical and biochemical characteristics of HPT were apparently unrelated to the presence or absence of LOH and the MEN1 gene mutations. However, the demonstration of LOH at 11q13 and MEN1 gene mutations in small parathyroid adenomas of patients with slight hypercalcemia and normal serum PTH levels suggest that altered MEN1 gene function may also be important for the development of mild sporadic pHPT.

Guidelines for diagnosis and therapy of MEN type 1 and type 2.

This is a consensus statement from an international group, mostly of clinical endocrinologists. MEN1 and MEN2 are hereditary cancer syndromes. The commonest tumors secrete PTH or gastrin in MEN1, and calcitonin or catecholamines in MEN2. Management strategies improved after the discoveries of their genes. MEN1 has no clear syndromic variants. Tumor monitoring in MEN1 carriers includes biochemical tests yearly and imaging tests less often. Neck surgery includes subtotal or total parathyroidectomy, parathyroid cryopreservation, and thymectomy. Proton pump inhibitors or somatostatin analogs are the main management for oversecretion of entero-pancreatic hormones, except insulin. The roles for surgery of most entero-pancreatic tumors present several controversies: exclusion of most operations on gastrinomas and indications for surgery on other tumors. Each MEN1 family probably has an inactivating MEN1 germline mutation. Testing for a germline MEN1 mutation gives useful information, but rarely mandates an intervention. The most distinctive MEN2 variants are MEN2A, MEN2B, and familial medullary thyroid cancer (MTC). They vary in aggressiveness of MTC and spectrum of disturbed organs. Mortality in MEN2 is greater from MTC than from pheochromocytoma. Thyroidectomy, during childhood if possible, is the goal in all MEN2 carriers to prevent or cure MTC. Each MEN2 index case probably has an activating germline RET mutation. RET testing has replaced calcitonin testing to diagnose the MEN2 carrier state. The specific RET codon mutation correlates with the MEN2 syndromic variant, the age of onset of MTC, and the aggressiveness of MTC; consequently, that mutation should guide major management decisions, such as whether and when to perform thyroidectomy.