vasoactive-intestinal-peptide and Insulinoma

Pancreatic neuroendocrine tumors (PNETs) are rare neoplasms representing <5% of all pancreatic malignancies with an estimated incidence of 1-1.5 cases/100,000. PNETs are broadly classified as either functional or nonfunctional. Functional PNETs include insulinomas, gastrinomas, vasoactive intestinal peptideomas, glucagonomas, and somatostatinomas. The clinical manifestations associated with these tumors are the result of excessive hormonal secretion and action. The functional nature of these tumors makes pancreatic hormone testing critical not only for initial diagnosis but also for follow-up, because they are important tumor markers. Nonfunctional PNETs typically remain clinically silent until a substantial mass effect occurs. Although the majority of PNETs occur sporadically, it is important to recognize that these tumors may be associated with a variety of familial syndromes and in many cases genetic testing of PNET patients is warranted. This article familiarizes the reader with the clinical presentation and the biochemical, radiologic, and genetic testing indicated for diagnosis and follow-up of patients with PNET.

Topics: Gastrinoma; Gastrins; Glucagon; Glucagonoma; Hormones; Humans; Hypoglycemia; Insulinoma; Neuroendocrine Tumors; Pancreatic Neoplasms; Somatostatinoma; Vasoactive Intestinal Peptide; Vipoma

Multiple Endocrine Neoplasia type 1 (MEN1) is a rare autosomal dominant hereditary cancer syndrome presented mostly by tumours of the parathyroids, endocrine pancreas and anterior pituitary, and characterised by a very high penetrance and an equal sex distribution. It occurs in approximately one in 30,000 individuals. Two different forms, sporadic and familial, have been described. The sporadic form presents with two of the three principal MEN1-related endocrine tumours (parathyroid adenomas, entero-pancreatic tumours and pituitary tumours) within a single patient, while the familial form consists of a MEN1 case with at least one first degree relative showing one of the endocrine characterising tumours. Other endocrine and non-endocrine lesions, such as adrenal cortical tumours, carcinoids of the bronchi, gastrointestinal tract and thymus, lipomas, angiofibromas, collagenomas have been described. The responsible gene, MEN1, maps on chromosome 11q13 and encodes a 610 aminoacid nuclear protein, menin, with no sequence homology to other known human proteins. MEN1 syndrome is caused by inactivating mutations of the MEN1 tumour suppressor gene. This gene is probably involved in the regulation of several cell functions such as DNA replication and repair and transcriptional machinery. The combination of clinical and genetic investigations, together with the improving of molecular genetics knowledge of the syndrome, helps in the clinical management of patients. Treatment consists of surgery and/or drug therapy, often in association with radiotherapy or chemotherapy. Currently, DNA testing allows the early identification of germline mutations in asymptomatic gene carriers, to whom routine surveillance (regular biochemical and/or radiological screenings to detect the development of MEN1-associated tumours and lesions) is recommended.

Topics: Adolescent; Adrenal Cortex Neoplasms; Adult; Aged; Aged, 80 and over; Angiofibroma; Carcinoid Tumor; Child; Facial Neoplasms; Female; Gastrinoma; Genetic Testing; Humans; Insulinoma; Lipoma; Male; Meningioma; Middle Aged; Multiple Endocrine Neoplasia Type 1; Pancreatic Neoplasms; Parathyroid Neoplasms; Pituitary Neoplasms; Prolactinoma; Proto-Oncogene Proteins; Thyroid Neoplasms; Vasoactive Intestinal Peptide; Young Adult

Gut peptide secreting tumours originate most commonly from the pancreatic Islets of Langerhans. Tumours at a variety of other sites have also been shown to synthesize and release these peptides, reflecting the wide distribution of the peptide secreting cells of the diffuse neuroendocrine system. Tumours such as the glucagonomas, insulinomas, VIPomas and gastrinomas are associated with characteristic clinical syndromes resulting from the effects of the peptide they secrete. The majority of the islet cell tumours in fact secrete a number of different peptides and many of these are present in several molecular forms, some of which may not be biologically active. This may explain the lack of clinical sequelae in association with tumours such as the somatostatinomas. The clinical features, methods of diagnosis, localisation and treatment of these tumours will be discussed.

Topics: Adenoma, Islet Cell; Bombesin; Bronchial Neoplasms; C-Peptide; Carcinoma, Small Cell; Diagnosis, Differential; Endocrine System Diseases; Erythema; Gastrointestinal Hormones; Glucagon; Glucagonoma; Humans; Insulin; Insulin Secretion; Insulinoma; Male; Neoplasms; Neurotensin; Pancreatic Hormones; Pancreatic Neoplasms; Pancreatic Polypeptide; Somatostatinoma; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

Intestinal adenocarcinomas and various endocrine tumors express large numbers of high-affinity receptors for vasoactive intestinal peptide (VIP). We have evaluated the usefulness of scanning with VIP labeled with iodine-123 for tumor localization in patients with gastrointestinal tumors.. Radioiodinated VIP was purified by high-pressure liquid chromatography and administered as a single intravenous bolus injection (300 pmol [1 microgram]). Scanning with radiolabeled VIP was compared with computed tomography and scanning with somatostatin analogues in 79 patients with colorectal cancer, pancreatic carcinoma, gastric cancer, carcinoid tumor, or insulinoma.. Visualization of gastrointestinal tumors and metastases was obtained with radiolabeled VIP. Binding of the labeled peptide by primary tumors and metastases was visible shortly after the injection and was still demonstrable at 24 hours. In patients with colorectal adenocarcinomas, primary or recurrent tumors were visualized in 10 of 10, liver metastases in 15 of 18, lung metastases in 2 of 3, and lymph-node metastases in 4 of 4. Primary pancreatic adenocarcinomas were visualized by imaging in 10 of 12 patients, and liver metastases were seen in 7 of 7. Primary or recurrent gastric adenocarcinomas were visualized in 5 of 5 patients, and liver metastases were seen in 2 of 2 patients. VIP scans were positive in 9 of 10 patients with carcinoid tumors and in 4 of 4 patients with insulinomas. Some tumors with positive VIP scans were also visualized with somatostatin analogues (4 of 17 colorectal adenocarcinomas, 8 of 9 carcinoids, and 2 of 2 insulinomas). In vitro binding studies confirmed the presence of VIP receptors on gastrointestinal tumors.. Scanning with radiolabeled VIP can visualize intestinal tumors and metastases that express receptors for VIP.

Topics: Adenocarcinoma; Carcinoid Tumor; Colorectal Neoplasms; Female; Gastrointestinal Neoplasms; Humans; Insulinoma; Iodine Radioisotopes; Male; Octreotide; Pancreatic Neoplasms; Radionuclide Imaging; Receptors, Somatostatin; Receptors, Vasoactive Intestinal Peptide; Stomach Neoplasms; Vasoactive Intestinal Peptide

Vasoactive intestinal polypeptide (VIP)-immunoreactive nerves have been demonstrated in close association with the islets of Langerhans, and VIP has been shown to stimulate insulin and somatostatin secretion. Using [125I]VIP and membranes prepared from rat insulinoma (RIN) cells, i.e., the subclones m5F (m5F; mainly insulin-secreting) and 14B (14B; mainly somatostatin-secreting), it was found that VIP (10(-10)-10(-7) M) competitively inhibited the binding of [125I]VIP. A single class of high affinity binding sites with Kd values of 0.40 +/- 0.06 nM and 0.36 +/- 0.08 nM for m5F and 14B, respectively, with a corresponding number of binding sites (Bmax) of 163 +/- 20 and 254 +/- 51 fmol/mg protein was observed. The rank order of potency in inhibiting [125I]VIP binding was in both cell lines: VIP greater than helodermin greater than pituitary adenylate cyclase activating polypeptide 1-27 (PACAP27) greater than peptide histidine isoleucine (PHI) greater than secretin. VIP caused a dose-dependent increase in cAMP-formation in both m5F and 14B cell membranes with EC50 values of 3.0 and 3.5 nM, respectively, but VIP (1.10(-9)-3.10(-6) M) had no effect on insulin secretion (over 2 h) from the m5F cells. Thus, the data suggest that the VIP-receptors in these neoplastic rat cell lines, despite an apparent coupling to adenylate cyclase activity, seem to be functionally uncoupled to an effect on insulin secretion following an acute exposure to VIP.

Topics: Adenylyl Cyclases; Animals; Cyclic AMP; Enzyme Activation; Insulin; Insulin Secretion; Insulinoma; Islets of Langerhans; Kinetics; Pancreatic Neoplasms; Radioligand Assay; Rats; Receptors, Gastrointestinal Hormone; Receptors, Vasoactive Intestinal Peptide; Tumor Cells, Cultured; Vasoactive Intestinal Peptide

Over a five-year period, we measured concentrations of gut hormones in plasma samples from 353 patients in whom diagnoses of pancreatic endocrine tumors were subsequently confirmed. A median of 19 months (range, 7 to 120) after the initial diagnosis, 24 of these patients (6.8 percent) had elevated concentrations of other hormones in association with new clinical symptoms. In 13 of these patients (8 with glucagonomas, 3 with tumors secreting vasoactive intestinal polypeptide, and 2 with insulinomas), hypergastrinemia developed along with the clinical features of a gastrinoma; 5 patients died of gastrointestinal perforation or bleeding, apparently caused by this second tumor. We conclude that patients with pancreatic endocrine tumors, regardless of their initial clinical picture, require continued surveillance for new elevations of hormones.

Topics: Adenoma, Islet Cell; Adult; Aged; Gastrins; Gastrointestinal Hemorrhage; Glucagon; Glucagonoma; Hormones; Humans; Insulinoma; Middle Aged; Pancreatic Neoplasms; Time Factors; Vasoactive Intestinal Peptide; Vipoma; Zollinger-Ellison Syndrome

Specific binding sites for 125I-labelled rat peptide-histidine-isoleucine (PHI) were identified on rat insulinoma-derived RINm5F cells. The concentrations of peptides producing half-maximal displacement of label were rat PHI, 0.36 +/- 0.14 nM, vasoactive intestinal polypeptide (VIP), 0.38 +/- 0.13 nM and secretin, approximately 0.2 microM. Glucagon and glucagon-like peptide-1(7-36)amide were without effect on binding. PHI and VIP produced dose-dependent increases in cAMP production in the cells that were significantly (P less than 0.05) above unstimulated rates for ligand concentrations between 10(-8) and 10(-6) M. Both PHI and VIP produced a small but significant (P less than 0.05) enhancement in the rate of release of immunoreactive insulin from the cells but the effect was not dose dependent.

Topics: Adenoma, Islet Cell; Adenylyl Cyclases; Animals; Cyclic AMP; Enzyme Activation; Insulin; Insulin Secretion; Insulinoma; Iodine Radioisotopes; Pancreatic Neoplasms; Peptide PHI; Rats; Receptors, Cell Surface; Receptors, Peptide; Tumor Cells, Cultured; Vasoactive Intestinal Peptide

Topics: Diagnosis, Differential; Humans; Hyperparathyroidism; Insulinoma; Multiple Endocrine Neoplasia; Pancreatic Neoplasms; Prolactin; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

Vasoactive intestinal polypeptide (VIP) is a 28-amino-acid hormone produced primarily by neural tissues. The amino acid sequence of VIP is similar to that of a number of gastrointestinal hormones, including glucagon and secretin. VIP is synthesized as part of a polyprotein, pre-proVIP, which generates, in addition to VIP, an additional bioactive peptide known as PHM. As a first step toward understanding the molecular basis of pre-proVIP gene expression, we have isolated the pre-proVIP gene and have determined its structure. The gene is approximately 9 kb long and is interrupted by six introns which appear to divide the gene into functional domains. One of the introns occurs within the 3'-untranslated region of the gene.

Topics: Amino Acid Sequence; Base Sequence; DNA; Gene Expression Regulation; Genes; Humans; Insulinoma; Islets of Langerhans; Peptide PHI; Peptides; Protein Precursors; Transcription, Genetic; Vasoactive Intestinal Peptide

Topics: Endocrine System Diseases; Enterochromaffin Cells; Female; Gastrointestinal Neoplasms; Glucagonoma; Humans; Insulinoma; Male; Multiple Endocrine Neoplasia; Pancreatic Neoplasms; Somatostatinoma; Stomach Neoplasms; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

A typical pancreatic insulinoma is characterized by immunohistochemistry which reflects its histogenesis, morphology and hormonal activity.

Topics: Adenoma, Islet Cell; Glucagon; Humans; Insulin; Insulinoma; Microscopy, Electron; Pancreatic Neoplasms; Somatostatin; Vasoactive Intestinal Peptide

Topics: Adenoma, Islet Cell; Humans; Insulinoma; Pancreatic Neoplasms; Vasoactive Intestinal Peptide; Vipoma; Zollinger-Ellison Syndrome

Topics: Adenoma, Islet Cell; Adult; Aged; Diabetes Mellitus; Diagnosis, Differential; Female; Glucagonoma; Humans; Insulinoma; Liver Neoplasms; Male; Middle Aged; Pancreatic Neoplasms; Skin Diseases; Somatostatinoma; Vasoactive Intestinal Peptide

In three families with the multiple endocrine adenomatosis type I (MEA I) trait, 51 members were investigated by measurement of circulating peptide hormones as tumor markers. Twenty-five of 51 members (49 percent) were considered to be affected by MEA I disorders. The incidence rose with age (75 percent in generation II). Both sexes were affected equally. Hyperparathyroidism was present in 20 of 25 affected members (80 percent), and pituitary tumors (prolactinomas) were found in four of 25 (16 percent). Endocrine pancreatic tumors were found in nine of 25 affected members (36 percent), but when "probable" tumors (seven) are included the frequency rises to 72 percent. Hyperparathyroidism was found in all except one member with proved lesions in other organs. Among patients with proved and possible endocrine pancreatic tumors, elevated serum levels of gastrin and pancreatic polypeptide were frequently found, 78 percent and 67 percent, respectively, and we suggest that serum gastrin and pancreatic polypeptide levels are the most useful screening markers at present for pancreatic lesions in MEA I.

Topics: Adenoma; Adolescent; Adult; Age Factors; Aged; Female; Gastrins; Humans; Hyperparathyroidism; Insulinoma; Liver Neoplasms; Male; Middle Aged; Multiple Endocrine Neoplasia; Pancreatic Neoplasms; Pancreatic Polypeptide; Parathyroid Neoplasms; Pedigree; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

Topics: Gastrointestinal Hormones; Glucagonoma; Humans; Insulinoma; Intestinal Mucosa; Somatostatinoma; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

One hundred twenty-five pancreatic endocrine tumors were analyzed by immunocytochemistry using various antisera. Twenty-three of 27 insulinomas, 10 of 10 PP-omas (PP: pancreatic polypeptide) and 15 of 30 "nonsecreting" tumors were benign, whereas 8 of 13 glucagonomas, 16 of 24 gastrinomas, and 16 of 21 VIP-omas (VIP: vasoactive intestinal polypeptide) were malignant. As a rule, the hormone secreted by the tumor and causing clinical symptoms could be localized by immunocytochemistry. Fifty of 95 active tumors were found to contain cells immunoreactive to peptide(s) not causing clinical symptoms, and 54 of 30 "nonsecreting" tumors were shown to be multicellular. By electron microscopy more than one cell type could be identified in 12 tumors. Histologically, the growth pattern of the tumors was very variable and distribution of immunoreactive cells was distinctly patchy. Radioimmunoassay on extracts of 20 of 27 tumors confirmed the presence of peptides visualized by immunocytochemistry. In 17 of 22 specimens, groups of endocrine cells in close contact with ductules were found in the pancreatic parenchyma distant from the tumor. Pancreatic endocrine tumors probably arise from the pancreatic ductular epithelium. They are often multicellular, producing and sometimes secreting more than one hormone or hormone-like substance. They represent highly complex biologic systems in which the interrelationship of various gastrointestinal-pancreatic hormones can be studied.

Topics: Adolescent; Adult; Aged; Child; Endocrine System Diseases; Female; Glucagonoma; Humans; Insulinoma; Male; Middle Aged; Pancreatic Neoplasms; Pancreatic Polypeptide; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome