Surgery of the primary tumour in 201 patients with high-grade gastroenteropancreatic neuroendocrine and mixed neuroendocrine-non-neuroendocrine neoplasms.

The benefit of surgery in high-grade gastroenteropancreatic neuroendocrine neoplasms (GEP NEN) and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) is uncertain. The present study aimed to investigate outcomes after tumour surgery in patients with high-grade (Ki-67 > 20%) GEP NEN or MiNEN stage I-III or stage IV. We analysed data from patients treated in the period 2007-2015 at eight Nordic university hospitals. Overall survival (OS) and progression-free survival (PFS)/disease-free survival (DFS) were analysed by Kaplan-Meier estimates. Prognostic factors were evaluated using Cox regression. We included 201 surgically resected patients, 143 stage I-III and 58 stage IV, with 68% having neuroendocrine carcinoma, 23% MiNEN, 5% neuroendocrine tumour G3 and 4% uncertain NEN G3. Primary tumours were located in colon/rectum (52%), oesophagus/cardia (19%), pancreas (10%), stomach (7%), jejunum/ileum (5%), duodenum (4%), gallbladder (2%) and anal canal (1%). For patients with stage I-III, median DFS was 12 months (95% confidence interval [CI] = 5.5-18.5) and median OS was 32 months (95% CI = 24.0-40.0). For patients with stage I-III and an R0 resection, median DFS was 21 months (95% CI = 4.9-37.1) and median OS was 39 months (95% CI = 25.0-53.0). For patients with stage IV, median PFS/DFS was 4 months (95% CI = 1.9-6.1) and median OS was 11 months (95% CI = 4.8-17.2). For patients with stage IV and an R0 resection, median DFS was 6 months (95% CI = 0-16.4) and median OS was 32 months (95% CI = 25.5-38.5). Performance status > 1 and colorectal primary were associated with poor prognosis. There was no difference in survival between patients with high-grade GEP NEN and MiNEN. Surgery of the primary tumour in patients with loco-regional high-grade GEP NEN or MiNEN led to good long-term results and should be considered if an R0 resection is considered achievable. Highly selected patients with stage IV disease may also benefit from surgery.

Histidine decarboxylase and urinary methylimidazoleacetic acid in gastric neuroendocrine cells and tumours.

AIM: To study histidine decarboxylase (HDC) expression in normal and neoplastic gastric neuroendocrine cells in relationship to the main histamine metabolite. METHODS: Control tissues from fundus (n = 3) and corpus (n = 3) mucosa of six patients undergoing operations for gastric adenocarcinoma, biopsy and/or gastric surgical specimens from 64 patients with primary gastric neuroendocrine tumours (GNETs), as well as metastases from 22 of these patients, were investigated using conventional immunohistochemistry and double immunofluorescence with commercial antibodies vs vesicular monoamine transporter 2 (VMAT-2), HDC and ghrelin. The urinary excretion of the main histamine metabolite methylimidazoleacetic acid (U-MeImAA) was determined using high-performance liquid chromatography in 27 of the 64 patients. RESULTS: In the gastric mucosa of the control tissues, co-localization studies identified neuroendocrine cells that showed immunoreactivity only to VMAT-2 and others with reactivity only to HDC. A third cell population co-expressed both antigens. There was no co-expression of HDC and ghrelin. Similar results were obtained in the foci of neuroendocrine cell hyperplasia associated with chronic atrophic gastritis type A and also in the tumours. The relative incidence of the three aforementioned markers varied in the tumours that were examined using conventional immunohistochemistry. All of these GNETs revealed both VMAT-2 and HDC immunoreactivity, and their metastases showed an immunohistochemical pattern and frequency similar to that of their primary tumours. In four patients, increased U-MeImAA excretion was detected, but only two of the patients exhibited related endocrine symptoms. CONCLUSION: Human enterochromaffin-like cells appear to partially co-express VMAT-2 and HDC. Co-expression of VMAT-2 and HDC might be required for increased histamine production in patients with GNETs.

Ghrelin and obestatin in human neuroendocrine tumors: expression and effect on obestatin levels after food intake.

BACKGROUND: Ghrelin and obestatin are derived from the same peptide hormone precursor and are mainly produced by the gastric mucosa. Ghrelin is involved in many biological processes, whereas the physiological function of obestatin needs further investigation. The aims of the present study were to establish the incidence of ghrelin- and obestatin-immunoreactive cells in a comprehensive panel of human neuroendocrine tumors (NETs) and to investigate if blood obestatin concentrations are influenced during a standardized meal stimulation test in healthy individuals and patients with NETs. MATERIALS AND METHODS: The expression of ghrelin and obestatin was investigated in NETs (n = 149) and other endocrine-related disorders (n = 3) using immunohistochemistry with specific polyclonal antibodies. Coexpression of the peptides was evaluated by double immunofluorescence. Concentrations of obestatin in blood were measured during a meal test in 6 healthy individuals and 5 patients with pancreatic NETs. RESULTS: Ghrelin and obestatin were expressed in 14/152 and 19/152 tumor tissues, respectively, mainly representing NETs of foregut origin and in pancreatic tissue from a nesidioblastosis patient. Double immunofluorescence staining showed colocalization of the peptides. During the meal test, obestatin levels in blood were unchanged in all patients but decreased significantly in the healthy individuals. CONCLUSION: Only a minority of NETs express ghrelin and obestatin. However, analysis of patients with tumors originating from tissues that express the peptides in normal conditions could be of importance. The results from the meal test indicate that the hormone levels are affected by food intake in healthy individuals, whereas obestatin levels remained unchanged in pancreatic NET patients.

Expression of ghrelin is correlated to a favorable outcome in invasive breast cancer.

BACKGROUND: Expression of the peptide hormones ghrelin and obestatin has previously been demonstrated in human mammary glands. However, the clinical implications of the expression of these peptides in breast cancer are unclear. The aim of this study was to investigate the potential clinical value of ghrelin and obestatin as breast cancer biomarkers. METHODS: A tissue microarray containing breast cancer specimens from 144 patients was immunostained with antibodies directed towards ghrelin and obestatin. Using varying cut-offs, the expression of the two peptides was evaluated and correlated to previously known prognostic factors in breast cancer and to the outcome. Cox regression analysis was used to assess whether these markers may predict survival of breast cancer patients. RESULTS: Moderate to strong immunoreactivity for ghrelin and obestatin was observed in 71.5% and 77.1% of the cases, respectively. Ghrelin and obestatin expression was significantly but weakly correlated to low histological grade, estrogen receptor positivity, small tumor size and low proliferation. Only ghrelin expression was significantly correlated to better recurrence-free and breast cancer-specific survival (HR = 0.3-0.4, p = 0.02-0.05) in both uni- and multivariate analyses. The optimal cut-off was any ghrelin expression versus none. Reproducibility between the two readers was very good for both stainings with kappa values of 0.94-1.00. CONCLUSIONS: Patients with tumors expressing ghrelin had 2.5-3 times lower risk for recurrence or breast cancer death than those lacking ghrelin expression. Ghrelin expression is easily assessable with high reproducibility using immunohistochemistry. Further investigations are needed to establish the clinical significance of ghrelin as a biomarker in breast cancer.

Altered expression of somatostatin receptors in pancreatic islets from NOD mice cultured at different glucose concentrations in vitro and in islets transplanted to diabetic NOD mice in vivo.

Somatostatin acts via five receptors (sst(1-5)). We investigated if the changes in pancreatic islet sst expression in diabetic NOD mice compared to normoglycemic mice are a consequence of hyperglycemia or the ongoing immune reaction in the pancreas. Pancreatic islets were isolated from NOD mice precultured for 5 days and further cultured for 3 days at high or low glucose before examined. Islets were also isolated from NOD mice and transplanted to normal or diabetic mice in a number not sufficient to cure hyperglycemia. After three days, the transplants were removed and stained for sst(1-5) and islet hormones. Overall, changes in sst islet cell expression were more common in islets cultured in high glucose concentration in vitro as compared to the islet transplantation in vivo to diabetic mice. The beta and PP cells exhibited more frequent changes in sst expression, while the alpha and delta cells were relatively unaffected by the high glucose condition. Our findings suggest that the glucose level may alter sst expressed in islets cells; however, immune mechanisms may counteract such changes in islet sst expression.

The biological hallmarks of ileal carcinoids.

Endocrine tumours derived from the small intestine, ileal carcinoids, produce and secrete the hormones tachykinins and serotonin, which induces the specific symptoms related to the tumour. Because of their low proliferation rate, they are often discovered at late stages when metastases have occurred. The biology that characterizes these tumours differs in many ways from what is generally recognized for other malignancies. In this overview, the current knowledge on the development and progression of ileal carcinoids is described.

A pilot genome-wide association study shows genomic variants enriched in the non-tumor cells of patients with well-differentiated neuroendocrine tumors of the ileum.

Genetic studies of midgut carcinoid cancer have exclusively focused on genomic changes of the tumor cells. We investigated the role of constitutional genetic polymorphisms in predisposing individuals to ileal carcinoids. In all, 239 cases and 110 controls were collected from three institutions: the Uppsala University Hospital; the Dana-Farber Cancer Institute; and the MD Anderson Cancer Center, and were genotyped using microarrays assaying >300 000 single nucleotide polymorphisms. Association with rs2208059 in KIF16B approached statistical significance (Mantel-Haenszel odds ratio=2.42, P=4.16×10(-7)) at a Bonferroni-corrected level (<1.62×10(-7)). Using two computational algorithms, four copy-number variants (CNVs) were identified in multiple cases that were absent in study controls and markedly less frequent in ∼1500 population-based controls. Of these four constitutional CNVs identified in blood-derived DNA, a 40 kb heterozygous deletion in Chr18q22.1 corresponded with a region frequently showing loss of heterozygosity (LOH) in ileal carcinoid tumor cells based on our meta-analysis of previously published cytogenetic studies (69.7% LOH, 95% confidence interval=60.0-77.9%). We analyzed the constitutional 40 kb deletion on chr18 in our study samples with a real-time quantitative PCR assay; 14/226 cases (6.19%) and 2/97 controls (2.06%) carried the CNV, although the exact boundaries of each deletion have not been determined. Given the small sample size, our findings warrant an independent cohort for a replication study. Owing to the rarity of this disease, we believe these results will provide a valuable resource for future work on this serious condition by allowing others to make efficient use of their samples in targeted studies.

Common pathogenetic mechanism involving human chromosome 18 in familial and sporadic ileal carcinoid tumors.

Serotonin producing endocrine carcinoma of small intestine (ileal carcinoid) is a clinically distinct endocrine tumor. It is generally considered as a sporadic disease and its molecular etiology is poorly understood. We report comprehensive clinical and molecular studies of 55 sporadic and familial patients diagnosed with this condition. Nine pedigrees encompassing 23 affected subjects were established, consistent with autosomal dominant mode of inheritance. Familial and sporadic patients demonstrated indistinguishable clinical pictures. Molecular analyses of 61 tumors from 45 individuals, including eight familial and 37 sporadic patients, aimed at determination of global copy number aberrations using BAC and Illumina SNP arrays and gene expression profiling by Affymetrix chips. Chromosome 18 aberrations were identified in both sporadic and in familial tumors; 100% vs. 38%, respectively. Other, less frequent aberrations were also common for both groups. Global expression profiles revealed no differentially expressed genes. Frequent gain of chromosome 7 was exclusively observed in metastases, when patient matched primary tumors and metastases were compared. Notably, the latter aberration correlated with solid growth pattern morphology (P < 0.01), a histopathological feature that has previously been related to worse prognosis. The clinical and molecular similarities identified between sporadic and familial cases suggest a common pathogenetic mechanism involved in tumor initiation. The familial variant of ileal carcinoid represents a previously unrecognized autosomal dominant inherited tumor disease, which we propose to call Familial Ileal Endocrine Carcinoma (FIEC). Our findings indicate the location of a FIEC tumor suppressor gene near the telomere of 18q, involved in development of inherited and sporadic tumors.

Connective tissue growth factor expression in endocrine tumors is associated with high stromal expression of alpha-smooth muscle actin.

OBJECTIVE: Complications due to fibrosis development are common in patients with well-differentiated endocrine carcinomas in the small intestine (ileal carcinoids). Connective tissue growth factor (CTGF) expression in ileal carcinoids may be related to this fibrosis development. This study aimed to examine CTGF expression in relation to local myofibroblast differentiation in a large series of ileal carcinoids and in different types of endocrine tumors. METHODS: Immunoreactivity (IR) for CTGF and α-smooth muscle actin (α-SMA), a marker for myofibroblasts, was compared in serial tumor tissue sections from 42 patients with ileal carcinoids and from 80 patients with other endocrine tumors. Western blot was performed on an additional 21 patients with ileal carcinoids. RESULTS: CTGF IR was present in >50% of tumor cells in all 42 ileal carcinoids and in 2 out of 14 endocrine pancreatic tumors, 4 out of 6 rectal carcinoids, and 1 out of 5 lung carcinoids. Tumors with abundant CTGF expression also displayed α-SMA IR in stromal fibroblast-like cells, whereas other endocrine tumors displayed less or no CTGF and α-SMA IR. Protein bands corresponding to full-length CTGF (36-42 kDa) were detected in protein lysates from ileal carcinoids. CONCLUSION: CTGF is uniquely prevalent in ileal carcinoids when compared with most other endocrine tumor types. Immunoreactive cells are adjacent areas with increased fibrovascular stroma that express α-SMA. This supports a potential role for CTGF in myofibroblast-mediated fibrosis associated with ileal carcinoids, and indicates that CTGF should be investigated as a target for future therapy.

Neuroendocrine markers are expressed in human mammary glands.

BACKGROUND: Regulatory peptides have previously been detected in epithelial cells of human mammary glands. As these peptides are produced by scattered neuroendocrine cells in the epithelium of other tissues the aim of this study was to investigate whether the mammary glands express molecular markers for neuroendocrine cells. MATERIAL AND METHODS: Specimens from 28 human mammary glands were retrieved. The distribution of immunoreactive cells was determined using immunohistochemistry with antibodies versus a set of endocrine markers including peptide hormones, chromogranins/secretogranins, vesicular monoamine transporters, synaptophysin, serotonin and synaptic vesicle protein 2. RESULTS: Cells of the luminal epithelium of ducts and lobules of human mammary glands expressed vesicular monoamine transporter 2 and chromogranin B, as well as the previously reported regulatory peptides obestatin, ghrelin, adrenomedullin and apelin. Using consecutive sections, it was revealed that the immunoreactivity patterns of the regulatory peptides and vesicular monoamine transporter 2 were similar. Interestingly, immunoreactivity for secretogranin II, secretogranin III and chromogranin B was identified in myoepithelial cells. No immunoreactivity was detected for chromogranin A or synaptophysin. CONCLUSION: Specific cells in the epithelium and myoepithelium of mammary glands express neuroendocrine markers suggesting that mammary glands may have neuroendocrine functions.

Obestatin/ghrelin cells in normal mucosa and endocrine tumours of the stomach.

OBJECTIVE: Obestatin and ghrelin are derived from the same gene and co-expressed in the same endocrine cells. Vesicular monoamine transporter-2 (VMAT-2), a marker for enterochromaffin-like (ECL) cells, is considered to be expressed in ghrelin cells. The aim was to establish if the two peptides and the transporter are co-expressed, both in normal gastric mucosa and in gastric endocrine tumours. DESIGN: An immunohistochemical study was performed on gastric biopsy material and on surgical specimens from 63 patients with gastric endocrine tumours and from individuals with normal gastric mucosa. Cells displaying obestatin immunoreactivity were examined regarding co-localization with ghrelin and VMAT-2. Both single- and double-immunostaining techniques were applied. Obestatin concentration in blood was measured in a subgroup of these patients. The results were correlated to various clinico-pathological parameters. RESULTS: In the normal mucosa, obestatin/ghrelin-immunoreactive cells rarely co-expressed VMAT-2. In most tumour tissue specimens, only a fraction of neoplastic cells displayed immunoreactivity to obestatin, and these cells always co-expressed ghrelin. Neoplastic obestatin-/ghrelin-IR cells invariably expressed VMAT-2, except for two ghrelinomas. The obestatin concentrations in blood were consistently low and did not correlate to clinico-pathological data. CONCLUSIONS: Obestatin and ghrelin immunoreactivity always occurred in the same endocrine cells in the gastric mucosa but these cells only occasionally co-expressed VMAT-2, opposite to the findings in tumours. These results indicate that endocrine cells expressing obestatin and ghrelin mainly differ from VMAT-2 expressing cells (ECL-cells) and can develop into pure ghrelinomas. Plasma concentrations of obestatin did not correlate to cellular expression.

Elevated plasma chromogranin A is the first indication of recurrence in radically operated midgut carcinoid tumors.

BACKGROUND: Patients with malignant midgut carcinoids are occasionally diagnosed with limited tumor spread, and surgery with radical intention is performed. Despite curative intent, recurrences occur frequently, motivating long-term biochemical and radiological follow-up. This study aimed to compare the usefulness of various methods in detecting such recurrences. METHODS: This retrospective study included 56 patients with radically operated midgut carcinoids referred to our University Hospital for evaluation and follow-up between 1985 and 2004. Patients were monitored 1-3 times per year using plasma-chromogranin A (P-CgA), urinary 5-hydroxyindoleacetic acid (U-5HIAA) concentrations as well as radiological examinations, including ultrasonography, computerized tomography or magnetic resonance investigation. In a subset of cases, somatostatin receptor scintigraphy and/or positron emission tomography with 5-hydroxytryptophan was performed. Time from operation until established recurrence was recorded. RESULTS: Tumor recurrence was established in 33 of 56 patients after a median of 32 months (range 6-217). Elevated P-CgA was the first marker to become pathologically elevated in 28 of these 33 patients (85%). In 3 of these 28 patients, radiology was simultaneously positive for a recurrence. CONCLUSION: P-CgA was the first marker to indicate tumor recurrence in the majority of radically operated midgut carcinoid patients. To avoid unnecessary and costly examinations in asymptomatic patients, we suggest that follow-up should comprise measurements of P-CgA twice a year and annual ultrasonography until P-CgA is elevated or clinical symptoms occur, at which time all efforts should be made to identify recurrent tumor lesions in order to give the patient the best possible treatment which, if possible, should be surgical removal of the recurrence.

Tachykinins in endocrine tumors and the carcinoid syndrome.

OBJECTIVE: A new antibody, active against the common tachykinin (TK) C-terminal, was used to study TK expression in patients with endocrine tumors and a possible association between plasma-TK levels and symptoms of diarrhea and flush in patients with metastasizing ileocecal serotonin-producing carcinoid tumors (MSPCs). METHOD: TK, serotonin and chromogranin A (CgA) immunoreactivity (IR) was studied by immunohistochemistry in tissue samples from 33 midgut carcinoids and 72 other endocrine tumors. Circulating TK (P-TK) and urinary-5 hydroxyindoleacetic acid (U-5HIAA) concentrations were measured in 42 patients with MSPCs before treatment and related to symptoms in patients with the carcinoid syndrome. Circulating CgA concentrations were also measured in 39 out of the 42 patients. RESULTS: All MSPCs displayed serotonin and strong TK expression. TK-IR was also seen in all serotonin-producing lung and appendix carcinoids. None of the other tumors examined contained TK-IR cells. Concentrations of P-TK, P-CgA, and U-5HIAA were elevated in patients experiencing daily episodes of either flush or diarrhea, when compared with patients experiencing occasional or none of these symptoms. In a Spearman partial rank test, the correlation of P-TK with daily diarrhea was independent of both U-5HIAA and CgA levels. CONCLUSION: We found that TK synthesis occurs in serotonin-IR tumors and that P-TK levels are significantly correlated with symptoms of flush and diarrhea in patients with MSPCs. This is, to our knowledge, the first report demonstrating an independent correlation of P-TKs with carcinoid diarrhea, a symptom that is customarily regarded as serotonin mediated. Further investigations may present opportunities for new therapeutic possibilities.

Distribution of obestatin and ghrelin in human tissues: immunoreactive cells in the gastrointestinal tract, pancreas, and mammary glands.

Obestatin and ghrelin are two peptides derived from the same prohormone. It is well established that ghrelin is produced by endocrine cells in the gastric mucosa. However, the distribution of human obestatin immunoreactive cells is not thoroughly characterized. A polyclonal antibody that specifically recognizes human obestatin was produced. Using this antibody and a commercial antibody vs ghrelin, the distribution of obestatin and ghrelin immunoreactive cells was determined in a panel of human tissues using immunohistochemistry. The two peptides were detected in the mucosa of the gastrointestinal tract, from cardia to ileum, and in the pancreatic islets. Interestingly, epithelial cells in the ducts of mammary glands showed distinct immunoreactivity for both ghrelin and obestatin. By double immunofluorescence microscopy, it was shown that all detected cells were immunoreactive for both peptides. Furthermore, the subcellular localization of obestatin and ghrelin was essentially identical, indicating that obestatin and ghrelin are stored in the same secretory vesicles.

Treatment with combined streptozotocin and liposomal doxorubicin in metastatic endocrine pancreatic tumors.

UNLABELLED: Treatment with combined streptozotocin and liposomal doxorubicin is safe and efficient in patients with endocrine pancreatic tumors (EPTs). No cardiac toxicity was reported. BACKGROUND: The combination of streptozotocin and doxorubicin has been shown to be superior to streptozotocin and fluorouracil in the treatment of metastatic EPTs. However, the risk of cardiac toxicity from anthracyclins hampers the usefulness of the drug combination. Liposomal doxorubicin has a lower frequency of cardiac adverse events compared to doxorubicin. We wanted to assess the efficacy and safety of combined streptozotocin and liposomal doxorubicin in patients with metastatic EPTs. METHODS: Thirty patients with metastatic EPTs were recruited from three medical centers in Norway and Sweden during a time period of 3 years. All patients had histopathologically confirmed diagnoses and bidimensionally measurable lesions. 30 mg/m(2) of liposomal doxorubicin was administered on day 1 of each cycle. During the first course, 1 g of streptozotocin was given on 5 consecutive days. Thereafter, 2 g of streptozotocin was given on day 1 only. Treatment was repeated every 3 weeks. RESULTS: Twelve of 30 patients (40%) achieved an objective radiological response with a median duration of 9 months. Stabilization of disease was achieved in 17 of 30 patients (57%) for a median duration of 11 months. Only one patient had progressive disease as best response. The 2-year progression-free survival was 18% and the 2-year overall survival was 72%. The treatment was well tolerated. None of the patients experienced cardiac toxicity. CONCLUSION: We conclude that combined streptozotocin and liposomal doxorubicin is a safe and efficient treatment for EPTs. The efficacy seems to be comparable to that of combined streptozotocin and doxorubicin, whereas the cardiac toxicity clearly favors using the liposomal drug combination.

Ghrelin immunoreactive cells in gastric endocrine tumors and their relation to plasma ghrelin concentration.

GOALS: Our aim was to elucidate the incidence and distribution pattern of ghrelin-immunoreactive (IR) cells in various types of human gastric endocrine tumors, and their surrounding mucosa, and relate the findings to total ghrelin concentrations in plasma. BACKGROUND: It has been demonstrated previously, that ghrelin-IR cells are present not only in normal human gastric oxyntic mucosa, but also in all types of enterochromaffinlike (ECL) cell carcinoids (ECL-CCs), and in mucosal regions affected by ECL cell hyperplasia. STUDY: Forty-eight gastric endocrine tumors were included in the study: 32 type I ECL-CCs, 3 type II, 9 type III, 1 non-ECL-CC, and 3 poorly differentiated endocrine carcinomas. The tumors were analyzed immunohistochemically with antibodies raised versus chromogranin A, synaptophysin, serotonin, somatostatin, vesicular monoamine transporter 2 and ghrelin. Total ghrelin in plasma was measured in 20 patients, using a commercial radioimmunoassay kit. RESULTS: Ghrelin-IR cells were found in all types I and II ECL-CCs but in only a few cases of the other tumors. Ghrelin-IR cells were also found among the hyperplastic endocrine cells in the mucosa surrounding types I and II, where they showed diffuse, linear, nodular and adenomatoid hyperplasia patterns. In type III ECL-CCs and poorly differentiated endocrine carcinomas, only diffuse and linear ghrelin-IR cell hyperplasia was present in the oxyntic mucosa in about half of the cases, whereas the mucosa of the non-ECL-CC did not show this feature. CONCLUSIONS: Despite the frequent occurrence of ghrelin-IR cells in both the neoplastic parenchyma and the oxyntic mucosa, plasma total ghrelin concentrations remained within the reference range and can therefore not be used as a clinical marker to identify ghrelin expressing ECL-CCs or ghrelin cell hyperplasia.

Endocrine pancreatic tumors: diagnosis and treatment.

Endocrine pancreatic tumors (EPTs) are uncommon, having an incidence of one per 100,000 people. They may appear as sporadic tumors or be associated with hereditary syndromes. EPTs are categorized as functioning or nonfunctioning tumors, based on the presence or absence of clinical syndromes. Among the former, insulinomas and gastrinomas are the most common. For the histopathological investigation of EPTs, chromogranin A and synaptophysin immunostainings are recommended. Measurement of circulating chromogranin A is also the cornerstone for the biochemical diagnosis of these tumors. Furthermore, specific hormones produced and released by the neoplastic cells can be identified by immunostaining and used for biochemical evaluation. To locate EPTs, both noninvasive (ultrasonography, computerized tomography, MRI and radionuclear imaging) and invasive techniques (arterial stimulation with venous sampling) can be used. Debulking procedures (surgery, radiofrequency ablation, embolization/chemoembolization and liver transplantation) and/or medical treatment (chemotherapy, biotherapy and peptide receptor radionuclide therapy) are the options available for the treatment of EPTs. Understanding the molecular events underlying the pathobiology of EPTs will aid the development of more accurate diagnostic/prognostic markers and give guidance for improved therapeutic modalities.

Malignant ileocaecal serotonin-producing carcinoid tumours: the presence of a solid growth pattern and/or Ki67 index above 1% identifies patients with a poorer prognosis.

Patients with malignant serotonin-producing carcinoid tumours in the jejunum, ileum and caecum generally have long survival expectancy. In some patients, however, tumour progression is more rapid and there is a need to identify them at an early stage. The purpose of this study was to determine if histopathological characteristics and/or Ki67 and apoptotic indices are of prognostic value in cases of metastatic disease. Eighty-one patients with this tumour were included in the study; all had metastases and their survival range was 1-223 months. Five growth patterns were identified and described. For 57 patients whose tumour material was available, the Ki67 and apoptotic indices were calculated for ten randomly selected tumour areas and 'hot spots'. A Cox regression analysis was used to test if histopathology and/or Ki67 index >/=1% could identify patients whose survival might be shorter than anticipated. One of the histopathological growth patterns-the solid (non-organoid) cell pattern-was correlated to shorter survival in both primary tumours and metastases, when compared with the organoid growth patterns (hazard ratio 2.9 and 2.3, p/=1%, in both primary tumour and metastases, identified patients at increased risk of shorter survival (hazard ratio 5.4 and 2.5, p/=1%, can be used to identify patients with a poorer prognosis. This study also showed that Ki67 index <2% cannot, as previously suggested, be used to indicate a benign progression for this tumour category.

Somatostatin induces rapid contraction of neuroendocrine cells.

The peptide hormone somatostatin, as well as the somatostatin analog octreotide, induces rapid morphological changes in neuroendocrine cells. The effect can be detected in less than 2 min: retraction fibers are formed, cells round up and cell-cell contacts are broken. Somatostatin-dependent cell contraction is inhibited by Y-27632, indicating that this effect is dependent on Rho kinase. In BON1 cells, the somatostatin-induced inhibition of forskolin-induced secretion of chromogranin A is not blocked by Y-27632. It is therefore concluded that the inhibitory effect of somatostatin in forskolin-stimulated cells is not dependent on cell contraction.

Expression of tyrosine kinase receptors in malignant midgut carcinoid tumors.

BACKGROUND: The expression of certain tyrosine kinase receptors (TKR) has been shown to have a prognostic value in many tumor entities. In recent years, inhibitors and monoclonal antibodies directed towards these receptors have been developed. Several have shown antitumoral effects and have been tested in clinical trials. We wanted to investigate whether midgut carcinoid tumors express TKR and therefore would be suitable for clinical trials with TKR inhibitors (TKRI) or monoclonal antibodies. MATERIAL AND METHODS: Tumor tissue from 36 patients (24 women and 12 men) with a malignant midgut carcinoid tumor was obtained. The tissues were examined with immunohistochemistry, using polyclonal antibodies against platelet-derived growth factor receptor-alpha (PDGFRalpha), platelet-derived growth factor receptor-beta (PDGFRbeta), epidermal growth factor receptor (EGFR) and c-kit. Human BON1 cells were cultivated and stimulated with PDGF-BB. We also present a case report of a patient with a malignant midgut carcinoid tumor who had stabilization of tumor growth during treatment with imatinib. RESULTS: Immunohistochemical staining for PDGFRalpha in tumor cells showed immunoreaction for the receptor in 13/34 (38%) for PDGFRbeta in 29/33 (88%), and 24/33 (73%) were immunoreactive for EGFR. No tumor tissue showed immunoreaction for c-kit. In tumor stroma PDGFRalpha was expressed in 35%, PDGFRbeta in 94% and EGFR in 9%. We show that human neuroendocrine tumor cells respond to PDGF, indicating that these tumors express functional PDGF receptors. CONCLUSION: Malignant midgut carcinoid tumors may express three of the four TKR tested in this investigation. Therefore, these tumors might be susceptible for treatment with TKRI or monoclonal antibodies and this should be further explored in clinical trials.