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.

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.

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.

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.

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.

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.

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 molecular targets for tyrosine kinase receptor antagonists in malignant endocrine pancreatic tumors.

PURPOSE: Molecular targeting with monoclonal antibodies and tyrosine kinase inhibitors is a novel approach to cancer treatment. We have examined the expression of molecular targets in patients with malignant endocrine pancreatic tumors, which is necessary to justify additional studies investigating the potential benefit from such treatment. EXPERIMENTAL DESIGN: Thirty-eight tumor tissues from malignant endocrine pancreatic tumors were examined with immunohistochemistry using specific polyclonal antibodies with regard to the expression pattern of platelet-derived growth factor receptors (PDGFRs) alpha and beta, c-kit, and epidermal growth factor receptor (EGFR). RESULTS: All 38 tissue specimens expressed PDGFRalpha on tumor cells, and 21 of 37 specimens (57%) expressed PDGFRalpha in tumor stroma (1 specimen was nonevaluable). Twenty-eight samples (74%) stained positive for PDGFRbeta on tumor cells, and 36 of 37 samples (97%) stained positive for PDGFRbeta in the stroma (1 specimen was nonevaluable). Thirty-five tumor tissues (92%) stained positive for c-kit, and 21 (55%) stained positive for EGFR on tumor cells. No differences were seen between syndromes or between poorly differentiated or well-differentiated tumors. Previous treatment did not influence expression pattern. Receptor expression pattern varied considerably between individuals. CONCLUSIONS: We have found that tyrosine kinase receptors PDGFRs alpha and beta, EGFR, and c-kit are expressed in more than half of the patients with endocrine pancreatic tumors. Because these receptors represent molecular targets for STI571 and ZD1839 (tyrosine kinase inhibitors) and IMC-C225 (a monoclonal antibody), we propose that patients suffering from EPTs might benefit from this new treatment strategy. However, because of great variability in receptor expression pattern, all patients' individual receptor expression should be examined.

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.

Malignant gastric ghrelinoma with hyperghrelinemia.

A characteristic feature of neuroendocrine tumors is production and release of peptide hormone. Ghrelin is a 28-amino acid hormone that stimulates GH release. In this paper, we describe a patient with a metastasizing gastric neuroendocrine tumor displaying intense immunoreactivity for ghrelin and extremely high circulating levels of ghrelin. Tumor tissue biopsies from the primary tumor and one liver metastasis were examined by immunohistochemistry. Ghrelin and several other hormones and tumor markers were measured in blood. The clinical course of the patient was followed. Tumor tissue biopsies showed immunoreactivity for cytokeratin, chromogranin A, human synaptic vesicle protein 2, synaptophysin, and ghrelin. Grossly elevated circulating levels of total ghrelin, 2100 microg/liter (reference interval < 5 microg/liter) and active ghrelin, 28 microg/liter (reference interval < 0.1 microg/liter) were found at presentation. Chromogranin A, chromogranin B, and calcitonin levels were also increased. Both total and active ghrelin increased, despite treatment, during follow-up of the patient. We have identified and characterized a patient with a malignant gastric neuroendocrine tumor secreting ghrelin as the main hormone. This might be a new tumor entity of the stomach, and it is suggested that patients with malignant gastric neuroendocrine tumors should be investigated for ghrelin production.

Expression and distribution of somatostatin receptor subtypes in the pancreatic islets of mice and rats.

Somatostatin acts on specific membrane receptors (sst(1-5)) to inhibit exocrine and endocrine functions. The aim was to investigate the distribution of sst(1-5) in pancreatic islet cells in normal mice and rats. Pancreatic samples from five adult C57BL/6 mice and Sprague-Dawley rats were stained with antibodies against sst(1-5) and insulin, glucagon, somatostatin, or pancreatic polypeptide (PP). A quantitative analysis of the co-localization was performed. All ssts were expressed in the pancreatic islets and co-localized on islet cells to various extents. A majority of the beta-cells expressed sst(1-2) and sst(5) in mouse islets, while < or =50% in the rat expressed sst(1-5). The expression of sst(1-5) on alpha-cells did not differ much among species, with sst(2) and sst(5) being highly expressed. About 70% of the delta-cells expressed sst(1-4) in the rat pancreas, whereas 50% of the islet cells expressed sst(1-5) in the mouse. Furthermore, 60% of the PP-cells expressed sst(1-5) in the mouse, while the rat islets had lower values. Co-expression with the four major islet hormones varies among species and sst subtypes. These similarities and differences are interesting and need further evaluation to elucidate their physiological role in islets.

Subtype selective interactions of somatostatin and somatostatin analogs with sst1, sst2, and sst5 in BON-1 cells.

Somatostatin is a polypeptide hormone acting as an inhibitor of pituitary, pancreatic, and gastrointestinal secretion through specific membrane receptors of which five subtypes have been cloned (sst(1-5)). Somatostatin analogs are used in the clinic to treat patients with excessive hormone production due to a neuroendocrine tumor. The aim of this study was to investigate the biological activity of three new somatostatin receptor subtype selective analogs (BIM-23926, sst(1)-selective; BIM-23120, sst(2)-selective; and BIM-23206, sst(5)-selective) in the human neuroendocrine tumor cell line, BON-1, which expresses sst(1), sst(2), and sst(5) natively. Somatostatin-14 and octreotide were used as reference substances. Forskolin-induced cAMP accumulation and chromogranin A (CgA) secretion were inhibited by BIM-23120, BIM-23206, and somatostatin-14 in a dose-dependent manner. Cholecystokinin (CCK-8) stimulated activation of mitogen-activated protein (MAP) kinase was inhibited by BIM-23120 and BIM-23206, while BIM-23926 stimulated the activity. Selective BIM analogs showed a more efficient inhibitory effect on cAMP accumulation, CgA secretion, and MAP kinase activity than octreotide in BON-1 cells. This may be explained by the differences in affinity of the ligand to the receptor or by interaction between different sst subtypes. We conclude that increasing knowledge about sst physiology and expression in malignant disease indicates a need for new analogs that can be incorporated into the therapeutic arsenal.

Expression of somatostatin receptor subtypes 1 to 5 in tumor tissue and intratumoral vessels in malignant endocrine pancreatic tumors.

Somatostatin analogs are well established in the treatment of malignant endocrine pancreatic tumors (EPTs). Our goal is to individualize their treatment using receptor-subtype-specific analogs and, therefore, exploring the receptor expression is highly important. We have examined the expression of somatostatin receptor (sst) subtypes 1-5 on tumor cells and in intratumoral vessels in 28 tumor tissues from malignant EPTs with immunohistochemistry using sst-subtype-specific polyclonal antibodies. We found that sst(2) and sst(4) stained positive in 90% and sst(1) in 70% of the tumor tissues, whereas sst(3) and sst(5) stained positive in only 50% of the tumor tissues. Sst expression in intratumoral vessels was high for sst(2) and sst(4) (80%), moderate for sst(1) (40%), and low for sst(3) and sst(5) (10%). The ssts were evenly distributed among the different tumor subtypes. However, tumors belonging to the same subgroup of EPTs showed a variable expression of receptor subtypes. No differences in receptor-subtype expression could be seen between poorly and welldifferentiated tumors, nor between primary tumors and metastases. Prior medical treatment did not influence sst expression pattern. In conclusion, sst(2) and sst(4) were expressed in most tumor tissues and intratumoral vessels from EPTs. However, sst(3) and sst(5) were lacking in half of the tumor tissues and in most of the intratumoral vessels. These differences indicate the importance of determining each tumor s subset of receptors before treatment with receptor-subtype-specific analogs is initiated. The importance of sst expression in intratumoral vessels is not yet known.

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.

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.

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.

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.

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.