Invasive Breast Carcinoma with Neuroendocrine Differentiation: A Single-Center Analysis of Clinical Features and Prognosis

Introduction Invasive breast cancer with neuroendocrine differentiation is a rare subtype of breast malignancy. Due to frequent changes in the definition of these lesions, the correct diagnosis, estimation of exact prevalence, and clinical behaviour of this entity may be challenging. The aim of this study was to evaluate the prevalence, clinical features, and outcomes in a large cohort of patients with breast cancer with neuroendocrine differentiation.

Patients Twenty-seven cases of breast cancer with neuroendocrine differentiation have been included in this analysis. Twenty-one cases were identified by systematic immunohistochemical re-evaluation of 465 breast cancer specimens using the neuroendocrine markers chromogranin A and synaptophysin, resulting in a prevalence of 4.5%. A further six cases were identified by a review of clinical records.

Results Median age at the time of diagnosis was 61 years. 70% of patients had T2 – 4 tumors and 37% were node-positive. The most common immunohistochemical subtype was HR-positive/HER2-negative (85%). 93% were positive for synaptophysin and 48% for chromogranin A. Somatostatin receptor type 2A status was positive in 12 of 24 analyzed tumors (50%). Neuroendocrine-specific treatment with somatostatin analogues was administered in two patients. The 5-year survival rate was 70%.

Conclusions Breast cancer with neuroendocrine differentiation is mostly HR-positive/HER2-negative and the diagnosis is made at a higher TNM stage than in patients with conventional invasive breast carcinoma. Moreover, breast cancer with neuroendocrine differentiation was found to be associated with impaired prognosis in several retrospective trials. Due to somatostatin receptor 2A expression, somatostatin receptor-based imaging can be used and somatostatin receptor-targeted therapy can be offered in selected cases.

Delta-Like Protein 3 Expression in Paired Chemonaive and Chemorelapsed Small Cell Lung Cancer Samples

Rovalpituzumab tesirine (Rova-T), an antibody-drug conjugate directed against Delta-like protein 3 (DLL3), is under development for patients with small cell lung cancer (SCLC). DLL3 is expressed on the majority of SCLC samples. Because SCLC is rarely biopsied in the course of disease, data regarding DLL3 expression in relapses is not available. The aim of this study was to investigate the expression of DLL3 in chemorelapsed (but untreated with Rova-T) SCLC samples and compare the results with chemonaive counterparts. Two evaluation methods to assess DLL3 expression were explored. Additionally, we assessed if DLL3 expression of chemorelapsed and/or chemonaive samples has prognostic impact and if it correlates with other clinicopathological data. The study included 30 paired SCLC samples, which were stained with an anti DLL3 antibody. DLL3 expression was assessed using tumor proportion score (TPS) and H-score and was categorized as DLL3 low (TPS < 50%, H-score ≤ 150) and DLL3 high (TPS ≥ 50%, H-score > 150). Expression data were correlated with clinicopathological characteristics. Kaplan–Meier curves were used to illustrate overall survival (OS) depending on DLL3 expression in chemonaive and chemorelapsed samples, respectively, and depending on dynamics of expression during course of therapy. DLL3 was expressed in 86.6% chemonaive and 80% chemorelapsed SCLC samples without significant differences between the two groups. However, the extent of expression varied in a substantial proportion of pairs (36.6% with TPS, 43.3% with H-score), defined as a shift from low to high or high to low expression. TPS and H-score provided comparable results. There were no profound correlations with clinicopathological data. Survival analysis revealed a trend toward a more favorable OS in DLL low-expressing chemonaive SCLC (p = 0.57) and, in turn, in DLL3 high-expressing chemorelapsed SCLC (p = 0.42) as well as in SCLC demonstrating a shift from low to high expression (p = 0.56) without being statistically significant. This is the first study to investigate DLL3 expression in a large cohort of rare paired chemonaive-chemorelapsed SCLC specimens. Comparative analysis revealed that DLL3 expression was not stable during the course of therapy, suggesting therapy-based alterations. Unlike in chemonaive samples, a high DLL3 expression in chemorelapsed samples indicated a trend for a more favorable prognosis. Our results highlight the importance to investigate DLL3 in latest chemorelapsed SCLC tumor tissue.

Gastric enterochromaffin-like cell changes in multiple endocrine neoplasia type 1

BACKGROUND

Gastric enterochromaffin-like cell (ECL) tumours can occur in patients with multiple endocrine neoplasia type 1 (MEN1), especially in those affected by Zollinger Ellison syndrome (ZES). Since the prevalence of ECL lesions is not well defined yet, the present study evaluated the presence and extent of ECL lesions in MEN1 patients with and without ZES.

METHODS

Multiple endocrine neoplasia type 1 patients being part of a regular screening program (2014-2018) underwent gastroduodenoscopies with biopsies of the stomach and determination of serum gastrin and chromogranin A levels. Haematoxylin- and immunostaining with chromogranin A, gastrin and VMAT I and II (vesicular monoamine transporter I and II) of the biopsies were performed.

RESULTS

Thirty-eight MEN1 patients, of whom 16 (42%) were diagnosed and treated earlier for ZES, were analysed. In ten of 16 (62.5%) ZES patients, a locally scattered, mixed image of diffuse, linear and micronodular mild hyperplasia was present. In addition, two of these patients (13%) showed small (max 1.5 mm in size) intramucosal ECL tumours. Neither ECL changes, nor tumours were found in MEN1 patients without ZES (n = 22). In MEN1/ZES patients, the median serum gastrin level was significantly elevated compared to MEN1 patients without ZES (206 pg/ml vs. 30.5 pg/ml, p < .001). A subgroup analysis of the serum gastrin and chromogranin A levels of MEN1/ZES patients with or without ECL hyperplasia did not show significant differences (gastrin level: p = .302, chromogranin A: p = .464).

CONCLUSION

Enterochromaffin-like cell hyperplasia and gastric carcinoids occur only in MEN1 patients with ZES, but less frequently than reported.

Primary Neuroendocrine Neoplasia of the Liver

ABSTRACT

The presence of primary neuroendocrine tumors in the liver is still a matter of controversy. We present a case of a somatostatin-receptor-positive mass of the liver in the 68Ga-DOTATOC PET/CT. No other primary tumor was found after conventional imaging, endoscopically, and after liver-segment resection. Immunohistochemically, a constellation of findings was found to be compatible with a primary neuroendocrine neoplasm of the liver.

[Neuroendocrine Neoplasia of the digestive tract]

Neuroendocrine Neoplasia of the digestive tract Abstract. Neuroendocrine neoplasia are a rare and heterogenous tumor entity with long median survival even in metastatic situation. Surgery is the key therapeutic option although a wide range of other therapies are available in metastatic situation. Milestones in classification and grading were achieved by the European Neuroendocrine Tumor Society (ENETS) leading to practical guidelines and WHO- and TNM-classification comparable to the colorectal carcinoma. These new guidelines enable the handling of a rare and complex tumor entity.

Long-term outcome of surgical resection in patients with gastroenteropancreatic neuroendocrine neoplasia: results from a German nation-wide multi-centric registry

BACKGROUND

Neuroendocrine neoplasia (NEN) are rare and heterogenous tumours. Few data exist on the impact of surgical therapy.

MATERIALS AND METHODS

This is a retrospective analysis of prospectively collected data of gastroenteropancreatic NEN in the German NET-Registry (1999-2012). It focuses on patients without distant metastases (limited disease, LD, stage I-IIIB).

RESULTS

Data of 2239 patients with NEN were recorded. Median age was 59 years, the gender ratio was 1:1.3 (f:m). A total of 986 patients (44%) had LD, and the 5-year survival rate (5 years) was 77% for all and 90% for patients with LD. A total of 1635 patients (73%) received a surgical therapy (1st to 6th line); the 5 and 10 ysr were 83/65% after and 59/35% without surgery for all patients (p < .001). The resection margins in the LD patients were 76%, 16%, and 3% for R0, R1 and R2, respectively. The 10 ysr was 84%, 59% and 42% for R0, R1 and R2 resections, respectively (p = .021 R0/R1, p < .001 R0/R2). The R0 resection rate was 75% for G1/G2 NET and 67% for G3 NEC.

CONCLUSION

The rate of complete tumour resection (R0) in LD is independent of tumour grading, and R0 resection is the key determinant of long-term survival, as demonstrated by the 10 ysr. of 84%. All NEN patients with limited disease should be considered for operation, if possible, as the best 10-year survival is shown after an R0 resection.

BRAFV600E mutation: A promising target in colorectal neuroendocrine carcinoma

To determine the role of BRAF^V600E mutation and MAPK signaling as well as the effects of BRAF and MEK directed therapy in gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN), with a focus on highly aggressive gastroenteropancreatic neuroendocrine carcinoma (GEP-NEC). Using Sanger sequencing of BRAF exon 15 we determined the frequency of BRAF^V600E mutations in 71 primary GEP-NENs. MEK phosphorylation was examined by immunohistochemistry in corresponding tissue samples. To evaluate the biological relevance of BRAF^V600E mutation and MAPK signaling in GEP-NECs, effects of a pharmacological BRAF and MEK inhibition were analyzed in NEC cell lines both in vitro and in vivo. BRAF^V600E mutation was detected in 9.9% of all GEP-NENs. Interestingly, only NECs of the colon harbored BRAF^V600E mutations, leading to a mutation frequency of 46.7% in this subgroup of patients. In addition, a BRAF^V600E mutation was significantly associated with high levels of MEK phosphorylation (pMEK) and advanced tumor stages. Pharmacological inhibition of BRAF and MEK abrogated NEC cell growth, inducing G1 cell cycle arrest and apoptosis only in BRAF^V600E mutated cells. BRAF inhibitor dabrafenib and MEK inhibitor trametinib prevented growth of BRAF^V600E positive NEC xenografts. High frequencies of BRAF^V600E mutation and elevated expression levels of pMEK were detected in biologically aggressive and highly proliferative colorectal NECs. We provide evidence that targeting BRAF oncogene may represent a therapeutic strategy for patients with BRAF mutant colorectal NECs.

Aberrant methylated key genes of methyl group metabolism within the molecular etiology of urothelial carcinogenesis

Urothelial carcinoma (UC), the most common cancer of the urinary bladder causes severe morbidity and mortality, e.g. about 40.000 deaths in the EU annually, and incurs considerable costs for the health system due to the need for prolonged treatments and long-term monitoring. Extensive aberrant  DNA methylation is described to prevail in urothelial carcinoma and is thought to contribute to genetic instability, altered gene expression and tumor progression. However, it is unknown how this epigenetic alteration arises during carcinogenesis. Intact methyl group metabolism is required to ensure maintenance of cell-type specific methylomes and thereby genetic integrity and proper cellular function. Here, using two independent techniques for detecting DNA methylation, we observed DNA hypermethylation of the 5'-regulatory regions of the key methyl group metabolism genes ODC1, AHCY and MTHFR in early urothelial carcinoma. These hypermethylation events are associated with genome-wide DNA hypomethylation which is commonly associated with genetic instability. We therefore infer that hypermethylation of methyl group metabolism genes acts in a feed-forward cycle to promote additional DNA methylation changes and suggest a new hypothesis on the molecular etiology of urothelial carcinoma.

Establishment of the First Well-differentiated Human Pancreatic Neuroendocrine Tumor Model

Clinical options for systemic therapy of neuroendocrine tumors (NET) are limited. Development of new drugs requires suitable representative in vitro and in vivo model systems. So far, the unavailability of a human model with a well-differentiated phenotype and typical growth characteristics has impaired preclinical research in NET. Herein, we establish and characterize a lymph node-derived cell line (NT-3) from a male patient with well-differentiated pancreatic NET. Neuroendocrine differentiation and tumor biology was compared with existing NET cell lines BON and QGP-1. In vivo growth was assessed in a xenograft mouse model. The neuroendocrine identity of NT-3 was verified by expression of multiple NET-specific markers, which were highly expressed in NT-3 compared with BON and QGP-1. In addition, NT-3 expressed and secreted insulin. Until now, this well-differentiated phenotype is stable since 58 passages. The proliferative labeling index, measured by Ki-67, of 14.6% ± 1.0% in NT-3 is akin to the original tumor (15%-20%), and was lower than in BON (80.6% ± 3.3%) and QGP-1 (82.6% ± 1.0%). NT-3 highly expressed somatostatin receptors (SSTRs: 1, 2, 3, and 5). Upon subcutaneous transplantation of NT-3 cells, recipient mice developed tumors with an efficient tumor take rate (94%) and growth rate (139% ± 13%) by 4 weeks. Importantly, morphology and neuroendocrine marker expression of xenograft tumors resembled the original human tumor.Implications: High expression of somatostatin receptors and a well-differentiated phenotype as well as a slow growth rate qualify the new cell line as a relevant model to study neuroendocrine tumor biology and to develop new tumor treatments. Mol Cancer Res; 16(3); 496-507. ©2018 AACR.

Loss of Chromosome 18 in Neuroendocrine Tumors of the Small Intestine: The Enigma Remains

BACKGROUND/AIMS

Neuroendocrine tumors of the small intestine (SI-NETs) exhibit an increasing incidence and high mortality rate. Until now, no fundamental molecular event has been linked to the tumorigenesis and progression of these tumors. Only the loss of chromosome 18 (Chr18) has been shown in up to two thirds of SI-NETs, whereby the significance of this alteration is still not understood. We therefore performed the first comprehensive study to identify Chr18-related events at the genetic, epigenetic and gene/protein expression levels.

METHODS

We did expression analysis of all seven putative Chr18-related tumor suppressors by quantitative real-time PCR (qRT-PCR), Western blot and immunohistochemistry. Next-generation exome sequencing and SNP array analysis were performed with five SI-NETs with (partial) loss of Chr18. Finally, we analyzed all microRNAs (miRNAs) located on Chr18 by qRT-PCR, comparing Chr18+/- and Chr18+/+ SI-NETs.

RESULTS

Only DCC (deleted in colorectal cancer) revealed loss of/greatly reduced expression in 6/21 cases (29%). No relevant loss of SMAD2, SMAD4, elongin A3 and CABLES was detected. PMAIP1 and maspin were absent at the protein level. Next-generation sequencing did not reveal relevant recurrent somatic mutations on Chr18 either in an exploratory cohort of five SI-NETs, or in a validation cohort (n = 30). SNP array analysis showed no additional losses. The quantitative analysis of all 27 Chr18-related miRNAs revealed no difference in expression between Chr18+/- and Chr18+/+ SI-NETs.

CONCLUSION

DCC seems to be the only Chr18-related tumor suppressor affected by the monoallelic loss of Chr18 resulting in a loss of DCC protein expression in one third of SI-NETs. No additional genetic or epigenetic alterations were present on Chr18.

Bronchopulmonary Neuroendocrine Neoplasms and Their Precursor Lesions in Multiple Endocrine Neoplasia Type 1

OBJECTIVE

The prevalence and clinical behavior of bronchopulmonary neuroendocrine tumors (bNET) associated with multiple endocrine neoplasia type 1 (MEN1) are not well defined. This study aimed to determine the prevalence, potential precursor lesions and prognosis of bNET in patients with MEN1.

METHODS

A database of 75 prospectively collected MEN1 cases was retrospectively analyzed for bNET. Patient characteristics, imaging and treatment were evaluated. Resection specimens of operated patients were reassessed by two specialized pathologists. Available CT scans of the whole cohort were reviewed to determine the prevalence of bronchopulmonary nodules.

RESULTS

Five of the 75 MEN1 patients (6.6%; 2 male, 3 female) developed histologically confirmed bNET after a median follow-up of 134 months. The median age at diagnosis of bNET was 47 years (range 31-67), and all patients were asymptomatic. Four patients underwent anatomic lung resections with lymphadenectomy; the remaining patient with multiple lesions had only a wedge resection of the largest bNET. Tumor sizes ranged from 7 to 32 mm in diameter, and all bNET were well differentiated. Two patients had lymph node metastases. Two of 4 reevaluated resection specimens revealed multifocal bNET, and 3 specimens showed tumorlets (up to 3) associated with multifocal areas of a neuroendocrine cell hyperplasia within the subsegmental bronchi. One bNET-related death (1.3%) occurred during long-term follow-up. Review of the available CT scans of the patients without proven bNET revealed small bronchopulmonary lesions (≥3 mm) in 16 of 53 cases (30.2%).

CONCLUSIONS

bNET in MEN1 might be more common than previously recognized. Their natural course seems to be rather benign. Multifocal tumorlets and multifocal neuroendocrine cell hyperplasia might represent their precursor lesions.

Cellularity, characteristics of hematopoietic parameters and prognosis in myelodysplastic syndromes

BACKGROUND

Myelodysplastic syndromes (MDS) present with a normo- or hyperplastic bone marrow in most cases. We aimed at a characterization of patients with different types of cellularity.

METHODS

We assessed marrow cellularity both by histology and cytology in 1270 patients and analyzed hematologic, cytogenetic, and prognostic parameters accordingly.

RESULTS

The concordance of the assessment of cellularity differed dramatically between histology and cytology as only 36.5% were described as hypocellular by both methods (P < 0.0005) (hypocellular 16.4%, normocellular 23.3%, hypercellular 60.3%). There were no major differences with regard to hematopoietic insufficiency. The presence of fibrosis was associated to hypercellular bone marrow. Median survival differed from 38 months in hypocellular, 42 months in normocellular, and 25 months in hypercellular MDS (P < 0.0005). AML progression rates were 33% for hypercellular MDS after 2 yr, whereas hypo- and normocellular had a progression rate of 19% after 2 yr (P = 0.018). IPSS and IPSS-R were able to identify different risk groups within all three cellularity groups.

CONCLUSION

Based on our data, hypocellular patients obviously do not present as a separate entity, as there were no striking differences with regard to cytogenetics and WHO types. Assessment of cellularity should be performed by histopathology.

Glucagon cell hyperplasia and neoplasia with and without glucagon receptor mutations

CONTEXT

Glucagon cell adenomatosis (GCA) was recently recognized as a multifocal hyperplastic and neoplastic disease of the glucagon cells unrelated to multiple endocrine neoplasia type 1 and von-Hippel-Lindau disease.

OBJECTIVE

The study focused on the molecular analysis of the glucagon receptor (GCGR) gene in GCA and a description of the clinicopathological features of GCA with and without GCGR mutations.

DESIGN

Pancreatic tissues from patients showing multiple glucagon cell tumors were morphologically characterized and macro- or microdissected. All exons of the GCGR gene were analyzed for mutations by Sanger and next-generation sequencing. Genotyping for all detected GCGR variants was performed in 2560 healthy individuals.

PATIENTS

Six patients with GCA, and the parents of one patient were included in the study.

MAIN OUTCOME MEASURES

The main outcome measures were the correlations between the patients' GCGR mutation status and the respective clinicopathological data.

RESULTS

GCGR germline mutations were found in three of six patients. Patient 1 harbored a homozygous stop mutation. This patient's parents showed an identical but heterozygous GCGR mutation. Patient 2 had two different heterozygous point mutations leading each to premature stop codons. Patient 3 exhibited two homozygous missense mutations. No GCGR mutations were identified in the three other patients and in a large cohort of healthy subjects. The patients harboring GCGR mutations exhibited a greater number of tumors and larger tumors than patients with wild-type GCGR. One of the patients with wild-type GCGR showed lymph node micrometastases.

CONCLUSIONS

GCA with GCGR germline mutations seems to follow an autosomal-recessive trait. By interrupting the GCGR signaling pathways GCGR mutations probably cause GCA via glucagon cell hyperplasia. GCA also occurs in patients without GCGR mutations, but seems to be associated with fewer and smaller tumors.

Novel prognostic markers revealed by a proteomic approach separating benign from malignant insulinomas

The prognosis of pancreatic neuroendocrine tumors is related to size, histology and proliferation rate. However, this stratification needs to be refined further. We conducted a proteome study on insulinomas, a well-defined pancreatic neuroendocrine tumor entity, in order to identify proteins that can be used as biomarkers for malignancy. Based on a long follow-up, insulinomas were divided into those with metastases (malignant) and those without (benign). Microdissected cells from six benign and six malignant insulinomas were subjected to a procedure combining fluorescence dye saturation labeling with high-resolution two-dimensional gel electrophoresis. Differentially expressed proteins were identified using nano liquid chromatography-electrospray ionization/multi-stage mass spectrometry and validated by immunohistochemistry on tissue microarrays containing 62 insulinomas. Sixteen differentially regulated proteins were identified among 3000 protein spots. Immunohistochemical validation revealed that aldehyde dehydrogenase 1A1 and voltage-dependent anion-selective channel protein 1 showed significantly stronger expression in malignant insulinomas than in benign insulinomas, whereas tumor protein D52 (TPD52) binding protein was expressed less strongly in malignant insulinomas than in benign insulinomas. Using multivariate analysis, low TPD52 expression was identified as a strong independent prognostic factor for both recurrence-free and overall disease-related survival.

Hyperplasia to neoplasia sequence of duodenal and pancreatic neuroendocrine diseases and pseudohyperplasia of the PP-cells in the pancreas

Hyperplastic changes of the neuroendocrine cell system may have the potential to evolve into neoplastic diseases. This is particularly the case in the setting of genetically determined and hereditary neuroendocrine tumor syndromes such as MEN1. The review discusses the MEN1-associated hyperplasia-neoplasia sequence in the development of gastrinomas in the duodenum and glucagon-producing tumors in the pancreas. It also presents other newly described diseases (e.g., glucagon cell adenomatosis and insulinomatosis) in which the tumors are (or most likely) also preceded by islet cell hyperplasia. Finally, the pseudohyperplasia of PP-rich islets in the pancreatic head is defined as a physiologic condition clearly differing from other hyperplastic-neoplastic neuroendocrine diseases.

Neuroendocrine tumors of the bronchopulmonary system (typical and atypical carcinoid tumors): current strategies in diagnosis and treatment. Conclusions of an expert meeting February 2011 in Weimar, Germany

Neuroendocrine tumors (NETs; syn. carcinoid tumors) are highly or moderately differentiated neoplasms. They comprise a large variety of rare and heterogeneous tumors with an estimated incidence of 3-5/100,000/year. They can arise in virtually every internal organ, but mainly occur in the gastroenteropancreatic and bronchopulmonary systems. Around 25% of the NETs are localized in the bronchopulmonary system. Approximately 2% of all lung tumors are NETs. According to the World Health Organization (WHO) classification of lung tumors, bronchopulmonary NETs are subdivided into typical carcinoids (TCs) and atypical carcinoids (ACs). The parameter with the highest impact on NET behavior and prognosis is the histological classification and staging according to the tumor/node/metastasis (TNM) system. The diagnosis of NETs is established by histological examination and the immunohistochemical detection of general neuroendocrine markers, such as chromogranin A (CgA) and synaptophysin. Serum markers and the use of functional imaging techniques are important additive tools to establish the diagnosis of a NET. The only curative option for lung NETs is complete surgical resection. Beyond that, the currently available interdisciplinary therapeutic options are local ablation, biotherapy (somatostatin analogues), or chemotherapy. New therapeutic options such as peptide receptor radionuclide therapy (PRRT) and molecularly targeted therapies achieve promising results and are under further evaluation. This report is a consensus summary of the interdisciplinary symposium 'Neuroendocrine Tumors of the Lung and of the Gastroenteropancreatic System (GEP NET) - Expert Dialogue' held on February 25-26, 2011 in Weimar, Germany. At this conference, a panel of 23 German experts shared their knowledge and exchanged their thoughts about research, diagnosis, and clinical management of NETs, whereby special attention was paid to NETs of the respiratory tract.

New model for gastroenteropancreatic large-cell neuroendocrine carcinoma: establishment of two clinically relevant cell lines

Recently, a novel WHO-classification has been introduced that divided gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) according to their proliferation index into G1- or G2-neuroendocrine tumors (NET) and poorly differentiated small-cell or large-cell G3-neuroendocrine carcinomas (NEC). Our knowledge on primary NECs of the GEP-system is limited due to the rarity of these tumors and chemotherapeutic concepts of highly aggressive NEC do not provide convincing results. The aim of this study was to establish a reliable cell line model for NEC that could be helpful in identifying novel druggable molecular targets. Cell lines were established from liver (NEC-DUE1) or lymph node metastases (NEC-DUE2) from large cell NECs of the gastroesophageal junction and the large intestine, respectively. Morphological characteristics and expression of neuroendocrine markers were extensively analyzed. Chromosomal aberrations were mapped by array comparative genomic hybridization and DNA profiling was analyzed by DNA fingerprinting. In vitro and in vivo tumorigenicity was evaluated and the sensitivity against chemotherapeutic agents assessed. Both cell lines exhibited typical morphological and molecular features of large cell NEC. In vitro and in vivo experiments demonstrated that both cell lines retained their malignant properties. Whereas NEC-DUE1 and -DUE2 were resistant to chemotherapeutic drugs such as cisplatin, etoposide and oxaliplatin, a high sensitivity to 5-fluorouracil was observed for the NEC-DUE1 cell line. Taken together, we established and characterized the first GEP large-cell NEC cell lines that might serve as a helpful tool not only to understand the biology of these tumors, but also to establish novel targeted therapies in a preclinical setup.

Encapsulation status of papillary thyroid microcarcinomas is associated with the risk of lymph node metastases and tumor multifocality

The management of papillary microcarcinoma (PMC) of the thyroid is controversial, especially after partial thyroid resection for benign thyroid disease. In order to detect prognostic factors for PMC, we analyzed 116 patients with PMC for encapsulation status and lymph node metastases. Between 10/1992 and 12/2010, 116 patients with PMC have been operated in our department (87 females, 29 males, median age 49 years). Eighty per cent of PMCs were diagnosed postoperatively. Seventy-six patients (66%) received a more extended resection with either thyroidectomy, near total thyroidectomy, or Dunhill operation either primarily or after completion operation, whereas 40 patients (34%) had only partial resection. Fifty patients (43%) received radioiodine (RIA) ablation. Lymph node metastases were found in 21 patients (18%). Univariate analysis showed four risk factors to be significantly associated with the risk of lymph node metastasis (p<0.05): male gender, younger age, age group<50 years and nonencapsulation of the tumor. Multivariate analysis demonstrated statistical significance for gender and tumor capsulation status. The tumor capsulation status also correlated with tumor multifocality. Our data show that the risk of lymph node metastases is significantly higher in partially or nonencapsulated PMC than in encapsulated specimens. We therefore suggest that the WHO classification should be extended to a compulsory notification of the encapsulation status in PMC.

Secondary malignancy in patients with sporadic neuroendocrine neoplasia

The incidence of neuroendocrine neoplasias (NENs), especially of the gastro-entero-pancreatic (GEP), system relatively increased over the past decades, as a result of advanced diagnostic tools, a better clinical awareness, and distinguished pathological diagnostic recognition. Previous reports hypothesized an increased risk for secondary malignancies in patients with NEN especially in GEP-NENs. The present study was designed to investigate the coincidence of NENs and secondary malignancies in a large patient collective. A retrospective analysis was performed on 161 patients (85 female and 76 male) with NEN of various origins. Clinical data of these patients, different classification systems (TNM/WHO), proliferations-based grading, and clinical follow-up were collected and analyzed. Out of 143 patients with a sporadic NEN, 15 (10.49 %) patients were identified with secondary malignant tumors. Median age at the time of the primary operation for NEN was 65 years, whereas the median age of initial diagnosis of associated tumors was 59 years. Mean follow-up time was 61 months. The risk of developing a secondary malignancy was most elevated for patients with an NEN of the lung, the stomach, and the ileum (60, 50 and 20 %, respectively). The spectrum of secondary malignancies included various types of cancer. Kaplan-Meier survival analysis shows a difference suggesting that patients with a secondary malignancy demonstrate a worse survival compared to patients without a secondary tumor; no significance was detected (p = 0.349). Our data suggest that secondary malignancies in patients with NEN's especially in GEP-NENs are found more frequently than in general population. Therefore, patients with NEN need a continuous and detailed follow-up. The reason for the increased incidence of secondary malignancies in patients with NENs remains to be elucidated.

Is minimal residual lymph node disease in papillary thyroid cancer of prognostic impact? An analysis of the epithelial cell adhesion molecule EpCAM in lymph nodes of 40 pN0 patients

This study was aimed to assess the extend of nodal microdissemination in patients with pN0 papillary thyroid carcinoma (PTC) using immunohistochemical analysis. In early stage PTC both, systematic lymphadenectomy as well as radio iodine treatment, aimed to eliminate occult nodal tumor involvement, are under controversial debate, since little is known about the extend of lymphatic microdissemination in these patients. Formalin embedded samples of the resected lymph nodes were systematically screened for the presence of disseminated tumor cells using immunohistochemistry (monoclonal antibody Ber-EP4). Clinical and histopathological parameters as well as the post-operative course were recorded. Survival data were analysed by the Kaplan-Meier method and the log rank test. Overall 321 lymph nodes of 40 patients were screened immunohistochemically. In 12.5% of the patients disseminated occult tumor cells were diagnosed. In addition to tumor resection 90% of the patients underwent adjuvant radio-iodine treatment. The mean observation period in our collective was 72 months. The detection of disseminated tumor cells did not correlate with clinicopathologic risk parameters and did not have significant influence on the prognosis of these patients. Immunohistochemical analysis enables the detection of disseminated tumor cells in patients with pN0 PTC. This finding seems to support the application of adjuvant radio iodine, even in early tumor stages.

Notch 1 tumor expression is lacking in highly proliferative pancreatic neuroendocrine tumors

To date, very little is known about the development of benign organic hyperinsulinism and its metastatic potential. Typical morphologic, biochemical, or genetic differentiations for benign or malign tumor course of insulinomas do not exist. As signaling pathways may affect pancreatic cancer development and the maintenance of the neoplastic phenotype, the purpose of this study was to examine the role of Notch1 expression in organic hyperinsulinism. We examined 32 well-differentiated pancreatic endocrine tumors (wd PET); 11 wd PET of unknown behavior (wd PET ub); and 15 wd pancreatic endocrine cancer (wd PEC) for Notch1 expression by immunohistochemistry. Demographic data, clinical data, and follow-up of all patients were analyzed. Islets of the Langerhans show the strongest Notch1 staining in nearly 90 %. Positive Notch1 staining was absent in the acinar of the pancreas. In patients with a wd PET more than every second tumor (56.3 %/n = 18/32) demonstrated a negative Notch1 staining. The other 14 patients were positive for Notch1. Tumors of unknown behavior (wd PET ub) and malignant insulinomas had no signs of Notch expression in contrast to benign insulinomas. Considering the clinical and histomorphological tumor behavior, no correlation between Notch1 expression and clinical data was found. The missing Notch expression in the malignant tumor course might be used as a potential predictive marker, but further studies are needed to investigate the underlying molecular mechanism.

Species-specific vesicular monoamine transporter 2 (VMAT2) expression in mammalian pancreatic beta cells: implications for optimising radioligand-based human beta cell mass (BCM) imaging in animal models

AIMS/HYPOTHESIS

Imaging of beta cell mass (BCM) is a major challenge in diabetes research. The vesicular monoamine transporter 2 (VMAT2) is abundantly expressed in human beta cells. Radiolabelled analogues of tetrabenazine (TBZ; a low-molecular-weight, cell-permeant VMAT2-selective ligand) have been employed for pancreatic islet imaging in humans. Since reports on TBZ-based VMAT2 imaging in rodent pancreas have been fraught with confusion, we compared VMAT2 gene expression patterns in the mouse, rat, pig and human pancreas, to identify appropriate animal models with which to further validate and optimise TBZ imaging in humans.

METHODS

We used a panel of highly sensitive VMAT2 antibodies developed against equivalently antigenic regions of the transporter from each species in combination with immunostaining for insulin and species-specific in situ hybridisation probes. Individual pancreatic islets were obtained by laser-capture microdissection and subjected to analysis of mRNA expression of VMAT2.

RESULTS

The VMAT2 protein was not expressed in beta cells in the adult pancreas of common mouse or rat laboratory strains, in contrast to its expression in beta cells (but not other pancreatic endocrine cell types) in the pancreas of pigs and humans. VMAT2- and tyrosine hydroxylase co-positive (catecholaminergic) innervation was less abundant in humans than in rodents. VMAT2-positive mast cells were identified in the pancreas of all species.

CONCLUSIONS/INTERPRETATION

Primates and pigs are suitable models for TBZ imaging of beta cells. Rodents, because of a complete lack of VMAT2 expression in the endocrine pancreas, are a 'null' model for assessing interference with BCM measurements by VMAT2-positive mast cells and sympathetic innervation in the pancreas.

[Neuroendocrine tumours of the GI tract--data from the German NET Registry]

BACKGROUND

Neuroendocrine tumours (NET) are rare and heterogeneous neoplasia. To obtain valid data on epidemiology, diagnostics, therapy, prognosis and risk factors is the aim of the German NET registry.

PATIENTS AND METHODS

Data from 2009 histologically proven NET were collected from 35 NET centres between 1999 and 2010. Data collection has been performed prospectively since 2004. Results: Median follow-up was 34.5 months and median age at diagnosis 56.4 years. Primary tumour localisations were pancreas (34.2%), midgut (5.8%), stomach (6.5%), bowel (6.9%), duodenum (4.8%) and neuroendocrine CUP (12.6%). Synchronous metastases were seen in 46% and second malignancies in 12%. From 860 patients, 402 (46.7%) had functional tumours with the following hormone excess syndromes: carcinoid syndrome (19.1%; n = 164), persistent hyperinsulinaemic hypoglycaemia (17.7%; n = 152), Zollinger- Ellison syndrome (7.1%; n = 61), glucagonoma (0.7%; n = 15), Verner-Morrison syndrome (0.4%; n = 8) and somatostatinoma syndrome(0.1%; n = 2). Surgical therapy was performed in 78%, therapy with somatostatin receptor analogues(SSA) in 28%, peptide radioreceptor therapy (PRRT) in 19%, chemotherapy in 18% and interferon therapy in 6.5%. Only surgery was done in 47%, whereas 53% received a second therapy. General mortality rate during follow-up was 14.9%. The tumour-specific survival rates for 2, 5 and 10 years were 94, 85 and 70%. The 5-year survival is dependent on the surgical or non-surgical therapy (82 versus 61%, p < 0.001) and also on the primary tumour site (90/30% for midgut, 85/65% for pancreas, p < 0.001). Grading (G1, G2, G3) based on proliferation index Ki-67 recommended by the ENETS guidelines and WHO classification is highly correlated to the 5-year survival rate (88, 82, 33%, p < 0.001).

CONCLUSION

The German NET registry provides valid multicentric data on NET in Germany. Surgical therapy is the most frequent and important therapy with good clinical outcome. In non-resectable, metastatic tumours, systemic therapies are common. Continuation and evaluation of the new WHO and TNM classifications for NET and their therapies will be a future focus of the registry.

Comprehensive re-sequencing of adrenal aldosterone producing lesions reveal three somatic mutations near the KCNJ5 potassium channel selectivity filter

Background

Aldosterone producing lesions are a common cause of hypertension, but genetic alterations for tumorigenesis have been unclear. Recently, either of two recurrent somatic missense mutations (G151R or L168R) was found in the potassium channel KCNJ5 gene in aldosterone producing adenomas. These mutations alter the channel selectivity filter and result in Na⁺ conductance and cell depolarization, stimulating aldosterone production and cell proliferation. Because a similar mutation occurs in a Mendelian form of primary aldosteronism, these mutations appear to be sufficient for cell proliferation and aldosterone production. The prevalence and spectrum of KCNJ5 mutations in different entities of adrenocortical lesions remain to be defined.

Materials and Methods

The coding region and flanking intronic segments of KCNJ5 were subjected to Sanger DNA sequencing in 351 aldosterone producing lesions, from patients with primary aldosteronism and 130 other adrenocortical lesions. The specimens had been collected from 10 different worldwide referral centers.

Results

G151R or L168R somatic mutations were identified in 47% of aldosterone producing adenomas, each with similar frequency. A previously unreported somatic mutation near the selectivity filter, E145Q, was observed twice. Somatic G151R or L168R mutations were also found in 40% of aldosterone producing adenomas associated with marked hyperplasia, but not in specimens with merely unilateral hyperplasia. Mutations were absent in 130 non-aldosterone secreting lesions.

KCNJ5 mutations were overrepresented in aldosterone producing adenomas from female compared to male patients (63 vs. 24%). Males with KCNJ5 mutations were significantly younger than those without (45 vs. 54, respectively; p<0.005) and their APAs with KCNJ5 mutations were larger than those without (27.1 mm vs. 17.1 mm; p<0.005).

Discussion

Either of two somatic KCNJ5 mutations are highly prevalent and specific for aldosterone producing lesions. These findings provide new insight into the pathogenesis of primary aldosteronism.

[Pathology of neuroendocrine neoplasms]

During the last 5 years the European Neuroendocrine Tumor Society (ENETS) has developed basic recommendations for a standardized pathological diagnosis and classification of neuroendocrine neoplasms (NEN) of the gastroenteropancreatic system. These were included in the novel classification of tumors of the digestive system by the World Health Organization (WHO 2010) and the TNM classification of the union for international cancer control (2009). This review presents the pathology diagnosis regarding (1) basic diagnosis, (2) clinically relevant optional diagnosis, (3) proliferation-based grading, (4) nomenclature and (5) TNM classification. It is emphasized that a standardized diagnosis of NEN, together with clinical and radiological findings, is crucial for prognostic stratification and optimal therapy of patients with NEN. Therefore a close interdisciplinary collaboration is essential.

Neuroendocrine neoplasms of the gastroenteropancreatic system: pathology and classification

Neuroendocrine neoplasms (NEN) appear homogeneous in terms of morphology, but constitute a very heterogeneous group of tumors in terms of biological and clinical features. NEN may occur in any organ, but are most commonly observed in the lung and the gastroenteropancreatic system (GEP). The European Neuroendocrine Tumor Society (ENETS) developed guidelines in the last 5 years to standardize and improve the diagnosis and therapy of GEP-NEN. Taking these guidelines into account, the TNM classification of the Union for International Cancer Control (UICC) was introduced in 2009. The new GEP-NEN classification of the World Health Organization (WHO) was presented 1 year later. According to the guidelines of the ENETS, the UICC, and the WHO, the pathology classification of NEN of GEP consists of several basic components: (1) evidence of the neuroendocrine nature of the tumor, (2) histological distinction between well and poorly differentiated tumors, (3) proliferation-based grading. (4) TNM staging (including data about vascular invasion and resection margins), (5) with reference to the clinical question: evidence of hormones and biogenic amines, and (6) optional, especially in cases of initial diagnosis of NEN: expression of the somatostatin receptor type 2A. Based on these criteria, a standardized prognostic stratification of GEP-NEN can be performed in combination with other clinical parameters. The novel classifications constitute the basis for selecting the procedures of molecular and metabolic imaging as well as for tumor-specific treatments and permit comparisons of larger tumor populations. Close interdisciplinary cooperation is a prerequisite.

Loss of PTEN expression in neuroendocrine pancreatic tumors

PTEN (phosphatase and tensin homologue deleted from chromosome 10) is a well established tumor suppressor gene, which was cloned to chromosome 10q23. PTEN plays an important role in controlling cell growth, apoptosis, cell adhesion, and cell migration. In various studies, a genetic change as well as loss of PTEN expression by different carcinomas has been described. To date, the role of PTEN as a differentiation marker for neuroendocrine tumors (NET) and for the loss of PTEN expression is still unknown. It is assumed that loss of PTEN expression is important for tumor progression of NETs. We hypothesize that PTEN might be used as a new prognostic marker. We report 38 patients with a NET of the pancreas. Tumor tissues were surgically resected, fixed in formalin, and embedded in paraffin. PTEN expression was evaluated by immunohistochemistry and was correlated with several clinical and pathological parameters of each individual tumor. After evaluation of our immunohistochemistry data using a modified Remmele Score, a widely accepted method for categorizing staining results for reports and statistical evaluation, staining results of PTEN expression were correlated with the clinical and pathological parameters of each individual tumor. Our data demonstrates a significant difference in survival with existence of lymph node or distant metastases. Negative patients show a significant better survival compared with positive patients. Furthermore, we show a significant difference between PTEN expression and WHO or TNM classification. Taken together, our data shows a positive correlation between WHO classification and the new TNM classification of NETs, and loss of PTEN expression as well as survival. These results strongly implicate that PTEN might be helpful as a new prognostic factor.

The immune system in neuroendocrine tumors

During the last 30 years the incidence of neuroendocrine tumors has increased considerably and the overall 5-year survival rate has not changed substantially. Conventional therapeutic approaches appear to show an unsatisfactory effect in the more insidious forms of malignancies. Hence, attempts were made to direct the patient's own immune system against cancer by vaccinating against different tumor antigens. Up to date, only sporadic achievements were demonstrated in the majority cases of vaccination trials. One of the main hindrances to a successful vaccination comprises tumor-immune-escape mechanisms. This review focuses on the current knowledge concerning tumor immunoevasion strategies and the immune system in neuroendocrine tumors.

Global histone modification pattern predicts poor prognosis in organic hyperinsulinism

Here we tested whether global histone modifications predict survival in organic hyperinsulinism and whether global histone modification pattern can be used to distinguish benign from malignant primary insulinoma. A tissue microarray (TMA) was built, using samples from 63 patients with organic hyperinsulinism. The TMA was classified according to the WHO classification of 2004 [WHO 1A: benign insulinoma (wdPET); WHO 1B: unknown behavior (wdPETub); WHO 2/3: malignant insulinoma (wdPEC/pdPEC)]. The TMA consisted of tissue cores from islands of Langerhans, primary insulinomas, lymph node metastases, and hepatic metastases. Immunohistochemistry was performed on consecutive TMA slides with antibodies against H3K9Ac, H3K18Ac, H4K12Ac, H3K4diMe, and H4R3diMe. The Remmele immunoreactive scoring system was used to classify the staining. The IHC staining results were correlated to the WHO-classification of 2004 as well as to clinical follow-up data (mean: 107 months; range: 1-312 months). A nuclear staining pattern was observed for all antibodies directed against histone H3 and H4 acetylation/methylation sites. We observed significant differences in the distribution of the medians across all investigated tissue types (H3K9Ac, p=0.004; H3K18Ac, p=0.001; H4K12Ac, p=0.006; H4R3diMe, p=0.002) except for H3K4diMe (p=0.183). Correlation of the histone modification with the WHO-classification and clinical follow-up data, showed in the dichotomized groups ["low" (score 0-3), "moderate" (4-7) vs. "high" (≥8)] that patients with lower H3K18Ac levels ("low + moderate") had a significantly decreased relapse-free survival vs. patients with high H3K18Ac levels (p=0.038). The WHO classification and age were also of significant prognostic impact upon univariate analysis. A backwards Cox proportional hazards model revealed the independent prognostic effekt of H3K18Ac levels. Our data revealed low K18 acetylation levels of histone H3 as independent prognostic factor in organic hyperinsulinism. This result warrants validation with independent data sets of organic hyperinsulinism, but is in line with several previous studies in different cancer entities. The broad applicability of this potential biomarker might lead to standardized diagnostic tests in near future and may help to manage insulinoma patients more effectively.

Coincidence of mature cystic teratoma and serotonin-producing neuroendocrine tumor of the ileum

Mature cystic teratomas are often found in gonadal sites, but are very rarely located extragonadally, for example, in retroperitoneum, mediastinum, central nervous system, lung, or liver. In the literature, only 10 cases of cystic teratoma originating from the diaphragm have been reported. Here, we report for the first time a metachronous occurrence of a benign mature cystic teratoma in the left diaphragm together with a serotonin-producing neuroendocrine tumor of the ileum. The 51-year-old, female patient received a partial resection of the ileum due to a neuroendocrine tumor (pT3N1M0) 4 years ago. Furthermore, she was operated for a benign cystadenoma of the right ovary 3 years ago. In her past medical history, she had an appendectomy in her childhood and a subtotal thyroidectomy 10 years ago. To our knowledge, this is the first report describing the metachronous occurrence of benign mature cystic teratoma in the diaphragm and a highly differentiated neuroendocrine tumor of the ileum. The possible coincidence of both diseases is discussed.

[Diagnostics and treatment in functional pancreatic neuroendocrine tumours]

Pancreatic neuroendocrine tumours (PNET) are rare entities with an annual incidence of < 100,000. About 1 - 2 % of pancreatic neoplasias are neuroendocrine tumours. About one third of these tumours secrete biologically active substances that lead to development of specific clinical syndromes. PNET may occur sporadically or in association with hereditary syndromes, such as multiple endocrine neoplasia type 1 (MEN1). Among the functional PNET, insulinomas and gastrinomas are the most common entities. In contrast, vasoactive intetinale peptide (VIP)-secreting tumours, glucagonomas, serotonin-secreting carcinoid tumors, and tumours with secretion of ectopic hormones, such as calcitonin, are extremely rare. Once diagnosis has been established on the basis of clinical and laboratory findings, localization of the source of pathologic hormone secretion is warranted. Imaging methods frequently used for localization of PNET comprise anatomical imaging modalities, computed tomography, and magnetic resonance imaging, endoscopic ultrasound, selective arterial catheterization with hepatic venous sampling, DTPA-octreotid scintigraphy and DOTA-D-Phe(1)-Tyr(3)-octreotid positron emission tomography. Therapy is based on the specific tumour entity and the extent of the disease. In the majority of patients, even in the case of malignant disease, a surgical approach is warranted, eventually combined with a medical treatment.

Increased numbers of tumor-lysing monocytes in cancer patients

Lymphatic infiltration is a well known phenomenon in different tumors including endocrine malignancies. However, little is known about the role of antigen-presenting cells and T cell activation in this context. The aim of our study was to investigate the quantity and function of CD14+/CD56+ monocytes in tumor patients including endocrine malignancies. First, these cells were characterized in peripheral blood of endocrine and non-endocrine cancer patients as well as in tumor tissue samples. Cancer patients had in mean 3.7 times more CD14+/CD56+ monocytes in the peripheral blood compared to healthy controls (p≤0.0001), while the highest frequencies were seen in patients with heavy tumor load. Importantly, these cells additionally expressed several NK cell markers. A proof of CD14+/CD56+ infiltrations into papillary thyroid carcinoma was shown by immunohistochemical analyses. Functional analyses revealed an apoptosis inducing capacity in vitro after IFN-α re-stimulation. Our data indicate the importance of tumor-lysing monocytes in antitumor immunity.

A new mutation in the menin gene causes the multiple endocrine neoplasia type 1 syndrome with adrenocortical carcinoma

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant tumor syndrome that may be caused by mutations in the MEN1 gene on 11q13. Loss of function of the tumor suppressor gene MEN1 leads to synchronous or metachronous appearance of neuroendocrine tumors arising from neuroendocrine cells of the parathyroid and pituitary glands, the duodenum and pancreatic islets, and other endocrine organs such as the adrenal cortex. We here present a patient with MEN1 who developed hyperparathyroidism, multiple well differentiated functionally inactive neuroendocrine tumors of the pancreas and an adrenal carcinoma. We describe a new mutation at codon 443 in the coding region of exon 9 in the MEN1 gene, where a cytosine residue was exchanged for adenosine (TCC > TAC) and, consequently, serine for tyrosine (p.Ser443Tyr; c.1328C > A). [corrected] Also, we provide clinical data that may add to the genotype-phenotype discussion. We conclude that the novel mutation in the MEN1 gene described herein was clinically relevant.

Aldosterone- and cortisol-co-secreting adrenal tumors: the lost subtype of primary aldosteronism

Current guidelines suggest proving angiotensin-independent aldosterone secretion in patients with primary aldosteronism (PA). It is further recommended to demonstrate unilateral disease because of its consequence for therapy. A general screening for excess secretion of other hormones is not recommended. However, clinically relevant autonomous aldosterone production rarely originates in adrenal tumors, compromised of zona glomerulosa cells only. This article reviews published data on aldosterone- and cortisol-co-secreting tumors and shows that pre-operative diagnosis of such a lesion is beneficial for patients. Overt or subclinical glucocorticoid hypersecretion may interfere with diagnostic studies, e.g. adrenal venous sampling, screening of familial forms of PA on the basis of serum 18-hydroxy-cortisol (18-OH-F) determination, and provoke glucocorticoid deficiency after surgical removal of the tumor. In addition, knowledge from histological and molecular studies in patients with aldosterone- and cortisol-co-secreting tumors challenges some concepts of the development of adrenal autonomy. The presence of an aldosterone- and cortisol-co-secreting adrenocortical tumor should be considered if a patient has i) PA and an adenoma that is larger than 2.5 cm, ii) cortisol that is non-suppressible with overnight low-dose dexamethasone, or iii) grossly elevated serum levels of hybrid steroids, such as 18-OH-F.

Chromogranin A as potential target for immunotherapy of malignant pheochromocytoma

Currently, no effective treatment for malignant pheochromocytoma exists. The aim of our study was to investigate the role of chromogranin A (CgA) as a specific target molecule for immunotherapy in a murine model for pheochromocytoma. Six amino acid-modified and non-modified CgA peptides were used for dendritic cell vaccination. Altogether, 50 mice received two different CgA vaccination protocols; another 20 animals served as controls. In vitro tetramer analyses revealed large increases of CgA-specific cytotoxic T cells (CTL) in CgA-treated mice. Tumors of exogenous applied pheochromocytoma cells showed an extensive infiltration by CD8+ T cells. In vitro, CTL of CgA-treated mice exhibited strong MHC I restricted lysis capacities towards pheochromocytoma cells. Importantly, these mice showed strongly diminished outgrowth of liver tumors of applied pheochromocytoma cells. Our data clearly demonstrate that CgA peptide-based immunotherapy induces a cytotoxic immune response in experimental pheochromocytoma, indicating potential for therapeutic applications in patients with malignant pheochromocytoma.

Induction of glutathione peroxidase 4 expression during enterocytic cell differentiation

Glutathione peroxidase 4 (GPx4), an abundant selenoenzyme, is ubiquitously expressed in a tissue-, cell- and differentiation-dependent manner, and it is localized in cytoplasmic, mitochondrial, and nuclear cellular compartments. Here, we report cytoplasmic and nuclear localization of GPx4 in Caco-2 intestinal epithelial cells. Enterocytic differentiation of Caco-2 cells triggers an increase in GPx4 mRNA and protein levels, mediated by enhanced promoter activity. We identified a combined cAMP response element (CREB) and CCAAT/enhancer binding protein (C/EBP) site as critical for the differentiation-triggered GPx4 promoter activity. Induction of GPx4 correlated with C/EBPα transcript levels during differentiation, suggesting a role of C/EBPα as regulator of enterocytic GPx4 expression. Consistent with the in vitro results, GPx4 protein was detected in cytoplasmic and nuclear compartments of enterocytes in human intestinal epithelia. GPx4 is uniformly expressed in colonic crypts and is differentially expressed along the crypt-to-villus axis in the small intestine with a more pronounced expression of GPx4 in the upper villi, which contain fully differentiated enterocytes. These data suggest that intestinal GPx4 expression is modulated by the enterocytic differentiation program, and the results support a direct role of nuclear GPx4 in the (selenium-dependent) prevention of oxidative damage in the gastrointestinal tract.

6-18F-fluoro-L-dihydroxyphenylalanine positron emission tomography is superior to 123I-metaiodobenzyl-guanidine scintigraphy in the detection of extraadrenal and hereditary pheochromocytomas and paragangliomas: correlation with vesicular monoamine transporter expression

CONTEXT

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) may be better detected by (18)F-fluorodihydroxyphenylalanine-positron emission tomography (FDOPA-PET) than (123)I-metaiodobenzyl-guanidine (123-I-MIBG) scintigraphy.

OBJECTIVE

The objective of the study was to correlate functional imaging results with immunohistochemical, molecular-genetic, and biochemical findings.

DESIGN AND SETTING

Thirty consecutive patients with suspected PHEO/PGL presenting at a tertiary referral centre were investigated in a prospective study.

PATIENTS

Twenty-five patients had confirmed PHEO/PGL. Thirteen of 25 patients had a hereditary PHEO/PGL syndrome (two multiple endocrine neoplasia II, six succinate dehydrogenase complex, subunit D, two succinate dehydrogenase complex, subunit B, one von Hippel Lindau tumor suppressor protein, two Neurofibromatosis-1), and 12 of 25 were classified as sporadic. Five patients had hormonally inactive adrenal incidentalomas.

MAIN OUTCOME MEASURES

In all patients computed tomography scan and/or magnetic resonance imaging as well as both 123-I-MIBG scintigraphy and FDOPA-PET were performed. Resected tumors were examined by immunohistochemistry for expression of the vesicular monoamine transporter (VMAT)-1 and -2 and other markers.

RESULTS

A total of 64 lesions were found with both functional imaging modalities. FDOPA-PET detected 62 lesions, whereas only 34 lesions were detected by 123-I-MIBG scintigraphy. This resulted in an overall sensitivity and specificity for FDOPA-PET of 98 and 100% and for MIBG of 53 and 91%, respectively. Comparable sensitivities were found for adrenal and extraadrenal abdominal lesions (94 vs. 97%), whereas in thoracic/cervical lesions, the sensitivity for 123-I-MIBG scintigraphy (15%) was inferior to that of FDOPA-PET imaging (100%). Immunohistochemistry demonstrated a lack of VMAT-1 expression in all MIBG-negative tumors. Clinical predictors for MIBG negativity were a predominant norepinephrine/normetanephrine secretion, an age less than 45 yr, and a hereditary cause.

CONCLUSION

FDOPA-PET is superior to 123-I-MIBG scintigraphy in patients with extraadrenal, predominantly noradrenaline-secreting, and hereditary types of PHEO/PGL. The lack of VMAT-1 expression predicts negativity for MIBG-scintigraphy.

Regulation of p53 isoform expression in renal cell carcinoma

Differential expression of p53 isoforms might participate in the marked resistance towards conventional chemotherapy of renal cell carcinomas (RCCs). Therefore, we analysed their differential expression and regulation in RCCs. RCCs expressed a more p53 activating isoform pattern during tumor initiation and progression, in vivo. In vitro, two cell lines exhibiting a similar sensitivity towards Topotecan-induced cell death revealed a similar induction of p53 target genes but strongly differed in their extent of apoptosis. Furthermore, they strongly differed in their basal expression patterns and differential regulation of the isoforms. In conclusion, our study examined for the first time the differential expression and regulation of all p53 isoforms in a tumor in vivo. Furthermore, novel results in our in vitro studies show that p53 isoforms are strongly differentially regulated by chemotherapy in RCCs and that expression and regulation of so-called "p53-target genes" are obviously at least in part regulated by other transcription factors. In addition, our original findings show that p53 isoform expression in RCC cell lines is of minor importance for sensitivity towards chemotherapy.

In vivo molecular imaging of somatostatin receptors in pancreatic islet cells and neuroendocrine tumors by miniaturized confocal laser-scanning fluorescence microscopy

The aim of the study was to evaluate real time in vivo molecular imaging of somatostatin receptors (sstrs) using a handheld miniaturized confocal laser scan microscope (CLM) in conjunction with fluorescein-labeled octreotate (OcF) in healthy mice and murine models of neuroendocrine tumors. For CLM a small rigid probe (diameter 7 mm) with an integrated single line laser (488 nm) was used (optical slice thickness 7 mum; lateral resolution 0.7 mum). OcF was synthesized via Fmoc solid-phase peptide synthesis and purified by HPLC showing high-affinity binding to the sstr2 (IC(50) 6.2 nmol). For in vitro evaluation, rat and human pancreatic cancer cells were used and characterized with respect to its sstr subtype expression and functional properties. For in vivo confocal imaging, healthy mouse pancreatic islet and renal tubular cells as well as immunoincompetent nude mice harboring sstr-expressing tumors were evaluated. Incubation of sstr-positive cells with OcF showed a specific time- and dose-dependent staining of sstr-positive cells. CLM showed rapid internalization and homogenous cytoplasmatic distribution. After systemic application to mice (n = 8), specific time-dependent internalization and cytoplasmatic distribution into pancreatic islet cells and tubular cells of the renal cortex was recorded. After injection in tumor-harboring nude mice (n = 8), sstr-positive cells selectively displayed a cell surface and cytoplasmatic staining. CLM-targeted biopsies detected sstr-positive tumor cells with a sensitivity of 87.5% and a specificity of 100% as correlated with ex vivo immunohistochemistry. CLM with OcF permits real-time molecular, functional, and morphological imaging of sstr-expressing cell structures, allowing the specific visualization of pancreatic islet cells and neuroendocrine tumors in vivo.

VHL inactivation is an important pathway for the development of malignant sporadic pancreatic endocrine tumors

A small subset of familial pancreatic endocrine tumors (PET) arises in patients with von Hippel-Lindau syndrome and these tumors may have an adverse outcome compared to other familial PET. Sporadic PET rarely harbors somatic VHL mutations, but the chromosomal location of the VHL gene is frequently deleted in sporadic PET. A subset of sporadic PET shows active hypoxia signals on mRNA and protein level. To identify the frequency of functionally relevant VHL inactivation in sporadic PET and to examine a possible prognostic significance we correlated epigenetic and genetic VHL alterations with hypoxia signals. VHL mutations were absent in all 37 PETs examined. In 2 out of 35 informative PET (6%) methylation of the VHL promoter region was detected and VHL deletion by fluorescence in situ hybridization was found in 14 out of 79 PET (18%). Hypoxia inducible factor 1alpha (HIF1-alpha), carbonic anhydrase 9 (CA-9), and glucose transporter 1 (GLUT-1) protein was expressed in 19, 27, and 30% of the 152 PETs examined. Protein expression of the HIF1-alpha downstream target CA-9 correlated significantly with the expression of CA-9 RNA (P<0.001), VHL RNA (P<0.05), and VHL deletion (P<0.001) as well as with HIF1-alpha (P<0.005) and GLUT-1 immunohistochemistry (P<0.001). These PET with VHL alterations and signs of hypoxia signalling were characterized by a significantly shortened disease-free survival. We conclude that VHL gene impairment by promoter methylation and VHL deletion in nearly 25% of PET leads to the activation of the HIF-pathway. Our data suggest that VHL inactivation and consecutive hypoxia signals may be a mechanism for the development of sporadic PET with an adverse outcome.