Randomized Controlled Trial of the Gastrin/CCK2 Receptor Antagonist Netazepide in Patients with Barrett's Esophagus.

Hypergastrinemia has been associated with high-grade dysplasia and adenocarcinoma in patients with Barrett's esophagus, and experimental studies suggest proinflammatory and proneoplastic effects of gastrin on Barrett's esophagus. This is of potential concern, as patients with Barrett's esophagus are treated with medications that suppress gastric acid production, resulting in increased physiologic levels of gastrin. We aimed to determine whether treatment with the novel gastrin/CCK2 receptor antagonist netazepide reduces expression of markers associated with inflammation and neoplasia in Barrett's esophagus. This was a randomized, double-blind, placebo-controlled trial of netazepide in patients with Barrett's esophagus without dysplasia. Subjects were treated for 12 weeks, with endoscopic assessment at baseline and at end of treatment. The primary outcome was within-individual change in cellular proliferation as assessed by Ki67. Secondary analyses included changes in gene expression, assessed by RNA-sequencing, and safety and tolerability. A total of 20 subjects completed the study and were included in the analyses. There was no difference between arms in mean change in cellular proliferation (netazepide: +35.6 Ki67+ cells/mm2, SD 620.7; placebo: +307.8 Ki67+ cells/mm2, SD 640.3; P = 0.35). Netazepide treatment resulted in increased expression of genes related to gastric phenotype (TFF2, MUC5B) and certain cancer-associated markers (REG3A, PAX9, MUC1), and decreased expression of intestinal markers MUC2, FABP1, FABP2, and CDX1 No serious adverse events related to study drug occurred. The gastrin/CCK2 receptor antagonist netazepide did not reduce cellular proliferation in patients with nondysplastic Barrett's esophagus. Further research should focus on the biological effects of gastrin in Barrett's esophagus.Prevention Relevance: Treatment of patients with Barrett's esophagus with a gastrin/CCK2 receptor antagonist did not have obvious chemopreventive effects.

Netazepide Inhibits Expression of Pappalysin 2 in Type 1 Gastric Neuroendocrine Tumors.

BACKGROUND & AIMS: In patients with autoimmune atrophic gastritis and achlorhydria, hypergastrinemia is associated with the development of type 1 gastric neuroendocrine tumors (gNETs). Twelve months of treatment with netazepide (YF476), an antagonist of the cholecystokinin B receptor (CCKBR or CCK2R), eradicated some type 1 gNETs in patients. We investigated the mechanisms by which netazepide induced gNET regression using gene expression profiling. METHODS: We obtained serum samples and gastric corpus biopsy specimens from 8 patients with hypergastrinemia and type 1 gNETs enrolled in a phase 2 trial of netazepide. Control samples were obtained from 10 patients without gastric cancer. We used amplified and biotinylated sense-strand DNA targets from total RNA and Affymetrix (Thermofisher Scientific, UK) Human Gene 2.0 ST microarrays to identify differentially expressed genes in stomach tissues from patients with type 1 gNETs before, during, and after netazepide treatment. Findings were validated in a human AGSGR gastric adenocarcinoma cell line that stably expresses human CCK2R, primary mouse gastroids, transgenic hypergastrinemic INS-GAS mice, and patient samples. RESULTS: Levels of pappalysin 2 (PAPPA2) messenger RNA were reduced significantly in gNET tissues from patients receiving netazepide therapy compared with tissues collected before therapy. PAPPA2 is a metalloproteinase that increases the bioavailability of insulin-like growth factor (IGF) by cleaving IGF binding proteins (IGFBPs). PAPPA2 expression was increased in the gastric corpus of patients with type 1 gNETs, and immunohistochemistry showed localization in the same vicinity as CCK2R-expressing enterochromaffin-like cells. Up-regulation of PAPPA2 also was found in the stomachs of INS-GAS mice. Gastrin increased PAPPA2 expression with time and in a dose-dependent manner in gastric AGSGR cells and mouse gastroids by activating CCK2R. Knockdown of PAPPA2 in AGSGR cells with small interfering RNAs significantly decreased their migratory response and tissue remodeling in response to gastrin. Gastrin altered the expression and cleavage of IGFBP3 and IGFBP5. CONCLUSIONS: In an analysis of human gNETS and mice, we found that gastrin up-regulates the expression of gastric PAPPA2. Increased PAPPA2 alters IGF bioavailability, cell migration, and tissue remodeling, which are involved in type 1 gNET development. These effects are inhibited by netazepide.

Targeting the Wnt Pathway and Cancer Stem Cells with Anti-progastrin Humanized Antibodies as a Potential Treatment for K-RAS-Mutated Colorectal Cancer.

Purpose: Patients with metastatic colorectal cancer suffer from disease relapse mainly due to cancer stem cells (CSC). Interestingly, they have an increased level of blood progastrin, a tumor-promoting peptide essential for the self-renewal of colon CSCs, which is also a direct ß-catenin/TCF4 target gene. In this study, we aimed to develop a novel targeted therapy to neutralize secreted progastrin to inhibit Wnt signaling, CSCs, and reduce relapses.Experimental Design: Antibodies (monoclonal and humanized) directed against progastrin were produced and selected for target specificity and affinity. After validation of their effectiveness on survival of colorectal cancer cell lines harboring B-RAF or K-RAS mutations, their efficacy was assessed in vitro and in vivo, alone or concomitantly with chemotherapy, on CSC self-renewal capacity, tumor recurrence, and Wnt signaling.Results: We show that anti-progastrin antibodies decrease self-renewal of CSCs both in vitro and in vivo, either alone or in combination with chemotherapy. Furthermore, migration and invasion of colorectal cancer cells are diminished; chemosensitivity is prolonged in SW620 and HT29 cells and posttreatment relapse is significantly delayed in T84 cells, xenografted nude mice. Finally, we show that the Wnt signaling activity in vitro is decreased, and, in transgenic mice developing Wnt-driven intestinal neoplasia, the tumor burden is alleviated, with an amplification of cell differentiation in the remaining tumors.Conclusions: Altogether, these data show that humanized anti-progastrin antibodies might represent a potential new treatment for K-RAS-mutated colorectal patients, for which there is a crucial unmet medical need. Clin Cancer Res; 23(17); 5267-80. ©2017 AACR.

Role of proton pump inhibitors in preventing hypergastrinemia-associated carcinogenesis and in antagonizing the trophic effect of gastrin.

Gastrin is the main hormone stimulating gastric acid secretion, but it exerts proliferative and anti-apoptotic actions on various cancer cell types, in addition to its well-known trophic effect on enterochromaffin-like cells. As treatment with proton pump inhibitors (PPIs) increases the biosynthesis and secretion of gastrin, it has been postulated that treatment with PPIs could increase the risk of cancer, especially in Barrett's esophagus, gastric carcinoids, and colorectal cancer (CRC). Some tumors produce gastrin of their own, which can act in an autocrine manner to promote tumor growth. In addition, gastrin is known to foster the tumor microenvironment. However, in spite of these potentially increased cancer risks due to PPI-induced hypergastrinemia, prospective, large-scale cohort studies did not show an increase in CRC prevalence. The question as to why the long-term use of PPIs was not associated with an increased cancer risk of CRC might be answered by the fact that the PPIs antagonized the trophic effects of hypergastrinemia. Furthermore, the blockade of proton pumps or potassium channels in cancer cells could limit the abnormal glycolytic energy metabolism of cancer cells. Apart from their suppressive effect on gastric acids, PPIs exert an anti-tumor effect through the selective induction of apoptosis as well as an anti-inflammatory effect, and they protect cells from developing chemo- or radiotherapeutic resistance. Moreover, the anti-carcinogenic actions of PPIs were augmented with PPI-induced hypergastrinemia. Together with their potential targeted killing of cancer stem cells, these effects demonstrate their potential anti-cancer actions.

Immunotherapy for gastric premalignant lesions and cancer.

Chronic atrophic gastritis, a precancerous change for gastric cancer, shows a loss of appropriate glands, Helicobacter pylori infection and autoimmune gastritis being the two main etiologic factors. While H. pylori eradication is the mandatory treatment for the former, no etiologic treatment is available for the latter, in which a Th1-type response, modulated by Tregs and Th17 cells, is involved. H. pylori-related atrophic gastritis is a risk factor for gastric adenocarcinoma, while autoimmune atrophic gastritis is also linked to a substantial risk of gastric type I carcinoid, related to the chronic stimulus exerted by hypergastrinemia on enterochromaffin-like cells. Several studies have been published on gastric cancer treatment through an active specific immunotherapy, aimed at improving the immunoregulatory response and increasing the circulating tumor-specific T cells. No study on immunotherapy of carcinoids is available but, in our experience, the administration of an antigastrin 17 vaccine induced carcinoid regression in two out of three patients treated.

Regulated endocrine-specific protein 18 (RESP18) is localized to and regulated in A-like cells and G-cells in rat stomach.

The regulated endocrine-specific protein 18 (RESP18) has previously been localized to different endocrine cells and neurons, in particular the pituitary gland and hypothalamus. It is found in the lumen of the endoplasmic reticulum and is degraded at the post-ER pre-Golgi compartment, and a role in processing of secreted peptides has been hypothesized. The present study examines localization of RESP18 in the gastrointestinal mucosa of rats by immunohistochemistry, and expression and regulation in response to hypergastrinemia induced by acid inhibition (pantoprazole), gastrin antagonism (YF476), fasting-refeeding and octreotide by mRNA measurements. RESP18 was mainly found in the gastric mucosa, but could also be detected in a few, scattered cells in the lower small intestine and in colon. In the antral mucosa, all RESP18 immunoreactivity was localized to ghrelin-producing A-like cells and gastrin-producing G-cells. In the corpus mucosa, a significant fraction, but not all of the RESP18 immunoreactive cells, were A-like cells. In both antrum and corpus, Resp18 mRNA seemed to vary similarly with the activation of the A-like cells, and in the antrum also with stimulation of the G-cells. This study demonstrates, for the first time, the localization of RESP18 to specific neuroendocrine cells of the gastrointestinal mucosa and that it seems to be regulated synchronously with the peptides secreted from these cells. This suggests that Resp18 may indeed have a functional role in the synthesis or storage of these gastrointestinal peptides.

Humoral regulation of heart rate during digestion in pythons (Python molurus and Python regius).

Pythons exhibit a doubling of heart rate when metabolism increases several times during digestion. Pythons, therefore, represent a promising model organism to study autonomic cardiovascular regulation during the postprandial state, and previous studies show that the postprandial tachycardia is governed by a release of vagal tone as well as a pronounced stimulation from nonadrenergic, noncholinergic (NANC) factors. Here we show that infusion of plasma from digesting donor pythons elicit a marked tachycardia in fasting snakes, demonstrating that the NANC factor resides in the blood. Injections of the gastrin and cholecystokinin receptor antagonist proglumide had no effect on double-blocked heart rate or blood pressure. Histamine has been recognized as a NANC factor in the early postprandial period in pythons, but the mechanism of its release has not been identified. Mast cells represent the largest repository of histamine in vertebrates, and it has been speculated that mast cells release histamine during digestion. Treatment with the mast cell stabilizer cromolyn significantly reduced postprandial heart rate in pythons compared with an untreated group but did not affect double-blocked heart rate. While this study indicates that histamine induces postprandial tachycardia in pythons, its release during digestion is not stimulated by gastrin or cholecystokinin nor is its release from mast cells a stimulant of postprandial tachycardia.

Gastroprotective effect of anti-cancer compound rohitukine: possible role of gastrin antagonism and H(+) K (+)-ATPase inhibition.

The present study was designed to evaluate the anti-ulcerogenic properties of an alkaloid chromane, rohitukine from Dysoxylum binectariferum. Anti-ulcer potential of rohitukine was assessed in cold restrained, pyloric ligated and ethanol induced ulcers in rats. In addition, rohitukine was tested in vitro for H(+) K(+)-ATPase inhibitory activity in gastric microsomes. Moreover, we studied the role of rohitukine on the cytosolic concentration of Ca(2+) in parietal cell-enriched cell suspension in order to ascertain its mechanism of action. Cytoprotective activity was evaluated through PGE(2) level. Rohitukine significantly attenuated the ulcers in cold restraint ulcer (CRU) model in a dose-related manner. Moreover, it significantly lowered the free acidity and pepsin activity in pyloric ligated rats while improved the depleted level of mucin. Furthermore, rohitukine significantly reversed the cold restrained-induced increase in gastrin level. Our in vitro study revealed that rohitukine moderately inhibited the microsomal H(+) K(+)-ATPase activity with respect to positive control omeprazole. Furthermore, rohitukine potently antagonized the gastrin-elicited increase in cytosolic Ca(2+) level in parietal cell-enriched suspension. In ethanol-induced gastric lesions in rats, rohitukine significantly inhibited the formation of erosions and increased PGE(2) content showing more potency than reference drug sucralfate. Our results thus suggest that rohitukine possess significant anti-ulcer and anti-gastrinic activity in rats. It is likely that gastro-protective influences of rohitukine are dependent partly on its acid-lowering potential and partly on cytoprotective property. The acid-reducing effect of rohitukine might be attributed to its lowering effect on gastrin production and/or antagonism of gastrin-evoked functional responses of parietal cells. Thus, rohitukine represent a useful agent in the treatment of peptic ulcer disease.

Bismuth ions inhibit the biological activity of non-amidated gastrins in vivo.

The peptide hormone gastrin binds two ferric ions with high affinity, and iron binding is essential for the biological activity of non-amidated gastrins in vitro and in vivo. Bi3+ ions also bind to glycine-extended gastrin17 (Ggly), but inhibit Ggly-induced cell proliferation and migration in gastrointestinal cell lines in vitro. The aims of the present study were firstly, to establish the mechanism by which Bi3+ ions inhibit the binding of Fe3+ ions to Ggly, and secondly, to test the effect of Bi3+ ions on the activity of non-amidated gastrins in vivo. The interaction between Bi3+ ions, Fe3+ ions and Ggly was investigated by ultraviolet spectroscopy. The effect of Bi3+ ions on colorectal mucosal proliferation was measured in three animal models. In vitro in the presence of Bi3+ ions the affinity of Fe3+ ions for Ggly was substantially reduced; the data was better fitted by a mixed, rather than a competitive, inhibition model. In rats treated with Ggly alone proliferation in the rectal mucosa was increased by 318%, but was reduced to control values (p < 0.001) in animals receiving oral bismuth plus Ggly. Proliferation in the colonic mucosa of mice overexpressing Ggly or progastrin was significantly greater than in wild-type mice, but was no greater than control (p < 0.01) in animals receiving oral bismuth. Thus a reduction in the binding of Fe3+ ions to Ggly and progastrin in the presence of Bi3+ ions is a likely explanation for the ability of oral bismuth to block the biological activity of non-amidated gastrins in vivo.

Blocking gastrin and CCK-B autocrine loop affects cell proliferation and apoptosis in vitro.

Gastrin and cholecystokinin-B receptor (CCK-B) were co-expressed in human gastric carcinoma tissues, suggesting that a functional autocrine loop, the gastrin and CCK-B receptor loop, may be presented in gastric cancer cells and play an important role in the pathogenesis and progression of gastric carcinomas. The present study was aimed at studying the effects of blocking the gastrin and CCK-B receptor loop on cell proliferation and apoptosis in gastric cancer cell line SGC-7901 cells (SGC-7901 cells). First, the expression of gastrin and CCK-B receptor mRNAs and gastrin protein in SGC-7901 cells were measured by RT-PCR and immunocytochemistry, respectively. Radioimmunoassay (RIA) was used to detect the concentrations of gastrin in culture medium. The gastrin-CCK-B receptor axis was blocked by using a specific neutralizing antibody against human gastrin and siRNA specifically targeting human CCK-B receptors, respectively. Flow cytometry was used to measure the cell cycle and apoptotic cells, and western blotting was used to measure the expression of CCK-B receptor, caspase-3, and matrix metalloproteinase-2 (MMP-2) in cells. The results showed that SGC-7901 cells not only coexpressed gastrin and CCK-B receptor mRNAs, but also endogenously secreted gastrin protein into the culture medium, thus forming gastrin-CCK-B receptor autocrine loop. Biologically, disrupting gastrin-CCK-B receptor autocrine loop by neutralizing the endogenous gastrin or by knocking down CCK-B receptor expression significantly inhibited the cell proliferation and decreased the percentage of cells residing in the S-phase of the cell cycle, and meanwhile promoted cell apoptosis and increased caspase-3 expression as well as decreased MMP-2 expression. An autocrine loop between endogenously secreted gastrin and CCK-B receptors may play a key role in the regulation of cell proliferation and apoptosis in SGC-7901 cells.

Reflections on some pilot trials of gastrin receptor blockade in pancreatic cancer.

The experience of synthesising a novel gastrin receptor antagonist gastrazole and taking it into 3 small clinical studies in pancreatic cancer in man is described. The need for such a compound is illustrated by the observation that inhibition of gastric acid secretion by H2 receptor antagonists results in hypergastrinaemia. A large number of cell types have gastrin receptors including pancreatic cancer cells which have been shown to be stimulated by gastrin. Small numbers of pancreatic cancer patients given gastrazole by continuous intravenous infusion showed prolonged survival compared with best supportive care or placebo, and equivalent survival to those given 5 fluouracil. The results suggest a greater benefit for patients with early stage disease. An alternative gastrin receptor antagonist YF 476 is also described which has the advantage of efficacy given by the oral route. This new compound requires to be studied in pancreatic cancer and other diseases associated with hypergastrinaemia.

Development of XPA067.06, a potent high affinity human anti-gastrin monoclonal antibody.

The peptide hormone gastrin is a key factor in regulation of gastric acid secretion. It has also been implicated in the development or maintenance of various types of cancer, such as pancreatic and stomach carcinoma. Inhibition of gastrin activity has potential for therapeutic use as a suppressor of acid secretion as well as an inhibitor of gastrin-responsive tumors. XPA067.06 is an affinity matured, 30 pM fully human anti-gastrin monoclonal antibody that was generated. The antibody was tested in a mouse gastric pH model to determine its effect on acid secretion. In this model, animals were treated with human gastrin, XPA067.06, and H2R or M1 receptor antagonists. Gastric fluid was collected and acid output was measured as a function of pH. XPA067.06 was shown to significantly inhibit gastrin-17-stimulated acid output for at least 48h. These results demonstrate that XPA067.06 effectively binds and neutralizes human gastrin-17 in vivo with rapid onset and prolonged duration of efficacy.

Gastroprotective action of orexin-A against stress-induced gastric damage is mediated by endogenous prostaglandins, sensory afferent neuropeptides and nitric oxide.

Orexin-A, identified in the neurons and endocrine cells in the gut, has been implicated in control of food intake and sleep behavior but little is known about its influence on gastric secretion and mucosal integrity. The effects of orexin-A on gastric secretion and gastric lesions induced in rats by 3.5 h of water immersion and restraint stress (WRS) or 75% ethanol were determined. Orexin-A (5-80 microg/kg i.p.) increased gastric acid secretion and attenuated gastric lesions induced by WRS and this was accompanied by the significant rise in plasma orexin-A, CGRP and gastrin levels, the gastric mucosal blood flow (GBF), luminal NO concentration and an increase in mRNA for CGRP and overexpression of COX-2 protein and the generation of PGE(2) in the gastric mucosa. Orexin-A-induced protection was abolished by selective OX-1 receptor antagonist, vagotomy and attenuated by suppression of COX-1 and COX-2, deactivation of afferent nerves with neurotoxic dose of capsaicin, pretreatment with CCK(2)/gastrin antagonist, CGRP(8-37) or capsazepine and by inhibition of NOS with L-NNA. This study shows for the first time that orexin-A exerts a potent protective action on the stomach of rats exposed to non-topical ulcerogens such as WRS or topical noxious agents such as ethanol and these effects depend upon hyperemia mediated by COX-PG and NOS-NO systems, activation of vagal nerves and sensory neuropeptides such as CGRP released from sensory nerves probably triggered by an increase in gastric acid secretion induced by this peptide.

Designing antibodies for the inhibition of gastrin activity in tumoral cell lines.

Gastrin and its derivatives are becoming important targets for immunotherapy of pancreatic, gastric and colorectal tumors. This study was conducted to design antibodies able to block gastrin binding to the gastrin/cholecystokinin-2 (CCK-2) receptor in order to delay tumor growth. The authors have used different gastrin molecules, combined with the diphtheria toxoid, to generate and select human single chain variable fragments (scFvs) as well as mouse monoclonal antibodies and scFvs against different regions of gastrin. There was a remarkable conservation in the antibody repertoire against gastrin, independently of the approach and the species. The germlines most frequently used in gastrin antibody formation were identified. Three different epitopes were identified in the gastrin molecule. The resulting mouse monoclonal antibodies and scFvs were analyzed for gastrin neutralization using Colo 320 WT cells, which overexpress the CCK-2 receptor. The gastrin neutralizing activity assay showed that N-terminal specific mouse monoclonal antibodies were more efficient to inhibit proliferation of Colo 320 WT cells than the anti-C terminal antibodies. Moreover, the human antigastrin scFvs obtained in this study inhibited significantly the proliferation of Colo 320 tumoral cells. These findings should contribute to a more rational design of antibody-based antigastrin therapies in cancer, including passive administration of human antibodies with blocking activity.

G17DT: an antigastrin immunogen for the treatment of gastrointestinal malignancy.

G17DT (Gastrimmune) is an antigastrin-17 immunogen, raising antibodies that blockade gastrin-stimulated tumor growth. It has completed Phase III trials in patients with pancreatic cancer, and Phase III trials in gastric cancer are planned. Preclinical studies have confirmed that the G17DT-induced antibodies both reduce gastrin-17-stimulated gastric acid secretion and inhibit gastrin from interacting with the cholecystokinin-2 receptor. The efficacy of both passive and active immunization with G17DT has been established in a number of tumor systems, with additive effects demonstrated in combination chemotherapy in pancreatic, colon and gastric tumor models. Phase I/II studies in advanced gastrointestinal malignancies have shown no systemic or autoimmune reactions to active immunization with G17DT. The use of an optimized dose and dosing schedule has yielded a high proportion of antibody responders (70%), with minimal side effects and antibody titers measurable within 2 - 4 weeks. Phase II trials of G17DT in combination with chemotherapy have also been conducted in gastric and colorectal cancer. A Phase III, multicenter, double-blind, randomized, controlled trial of G17DT versus placebo in patients with advanced pancreatic cancer confirmed improved survival of patients in the G17DT group through an intention-to-treat analysis. The results of a randomized, double-blind, multinational, multicenter study of G17DT in combination with gemcitabine versus placebo and gemcitabine in patients with advanced pancreatic cancer failed to show improved overall survival except on subset analysis of patients with high antibody titers. Therefore, G17DT represents an emerging new modality for gastrointestinal malignancy.

Gastrin - active participant or bystander in gastric carcinogenesis?

Gastrin is a pro-proliferative, anti-apoptotic hormone with a central role in acid secretion in the gastric mucosa and a long-standing association with malignant progression in transgenic mouse models. However, its exact role in human gastric malignancy requires further validation. Gastrin expression is tightly regulated by two closely associated hormones, somatostatin and gastrin-releasing peptide, and aspects of their interaction may be deregulated during progression to gastric adenocarcinoma. Furthermore, agonists and antagonists of the receptors for all three hormones have shown modest clinical efficacy against gastric adenocarcinoma, which might provide useful information on the future combined use of these agents.

The KCNE2 potassium channel ancillary subunit is essential for gastric acid secretion.

Genes in the KCNE family encode single transmembrane domain ancillary subunits that co-assemble with voltage-gated potassium (Kv) channel alpha subunits to alter their function. KCNE2 (also known as MiRP1) is expressed in the heart, is associated with human cardiac arrhythmia, and modulates cardiac Kv alpha subunits hERG and KCNQ1 in vitro. KCNE2 and KCNQ1 are also expressed in parietal cells, leading to speculation they form a native channel complex there. Here, we disrupted the murine kcne2 gene and found that kcne2 (-/-) mice have a severe gastric phenotype with profoundly reduced parietal cell proton secretion, abnormal parietal cell morphology, achlorhydria, hypergastrinemia, and striking gastric glandular hyperplasia arising from an increase in the number of non-acid secretory cells. KCNQ1 exhibited abnormal distribution in gastric glands from kcne2 (-/-) mice, with increased expression in non-acid secretory cells. Parietal cells from kcne2 (+/-) mice exhibited normal architecture but reduced proton secretion, and kcne2 (+/-) mice were hypochlorhydric, indicating a gene-dose effect and a primary defect in gastric acid secretion. These data demonstrate that KCNE2 is essential for gastric acid secretion, the first genetic evidence that a member of the KCNE gene family is required for normal gastrointestinal function.

Gastrin enhances the angiogenic potential of endothelial cells via modulation of heparin-binding epidermal-like growth factor.

This study examined whether gastrin modulates endothelial cell activity via heparin-binding epidermal growth factor-like growth factor (HB-EGF) expression. Human umbilical vascular endothelial cells (HUVEC) were assessed for tubule formation in the presence of amidated gastrin-17 (G17) and glycine-extended gastrin-17 (GlyG17) peptides. HB-EGF gene and protein expressions were measured by quantitative reverse transcription-PCR, immunocytochemistry, and Western blotting, and HB-EGF shedding by ELISA. Matrix metalloproteinases MMP-2, MMP-3, and MMP-9 were assessed by Western blotting. Chick chorioallantoic membrane studies measured the in vivo angiogenic potential of gastrin and microvessel density (MVD) was assessed in large intestinal premalignant lesions of hypergastrinaemic APC(Min) mice. MVD was also examined in human colorectal tumor and resection margin normals and correlated with serum-amidated gastrin levels (via RIA) and HB-EGF protein expression (via immunohistochemistry). HUVEC cells showed increased tubule and node formation in response to G17 (186%, P < 0.0005) and GlyG17 (194%, P < 0.0005). This was blockaded by the cholecystokinin-2 receptor (CCK-2R) antagonists JB95008 and JMV1155 and by antiserum to gastrin and HB-EGF. Gastrin peptides increased HB-EGF gene expression/protein secretion in HUVEC and microvessel-derived endothelial cells and the levels of MMP-2, MMP-3, and MMP-9. G17 promoted angiogenesis in a chorioallantoic membrane assay, and MVD was significantly elevated in premalignant large intestinal tissue from hypergastrinaemic APC(Min) mice. In terms of the clinical situation, MVD in the normal mucosa surrounding colorectal adenocarcinomas correlated with patient serum gastrin levels and HB-EGF expression. Gastrin peptides, acting through the CCK-2R, enhance endothelial cell activity in models of angiogenesis. This may be mediated through enhanced expression and shedding of HB-EGF, possibly resulting from increased activity of matrix metalloproteinases. This proangiogenic effect translates to the in vivo and human situations and may add to the tumorigenic properties attributable to gastrin peptides in malignancy.

Presentation, treatment, and outcome of type 1 gastric carcinoid tumors.

BACKGROUND AND OBJECTIVES: The aim of this study was to review the presentation, treatment, and outcome of patients with Type 1 gastric carcinoid tumors. METHODS: A retrospective review of 1,600 carcinoid patients was analyzed to identify patients with gastric carcinoid tumors. RESULTS: Eighteen patients were found to have biopsy-confirmed Type 1 gastric carcinoid tumors on upper endoscopy. Reasons for endoscopy included abdominal pain (n = 4), gastrointestinal bleeding (n = 4), surveillance for pernicious anemia (n = 8), and other (n = 2). The mean pre-treatment serum gastrin and chromogranin A levels were 1,436 ng/ml (+/-771 ng/ml) and 91.6 ng/ml (+/-68.6 ng/ml), respectively. Imaging revealed evidence of gastric carcinoid in 4 of 10 patients undergoing CT scanning and 3 of 10 patients undergoing octreotide scintigraphy. Of the 18 patients, 8 were treated medically (acidification or octreotide) and 10 were treated with surgery (laparoscopic antrectomy or partial gastrectomy). Mean gastrin levels decreased by 37.2% in the medically treated group (median follow-up 6 months), versus 94.0% in the surgically treated patients (median follow-up 5 months). Mean chromogranin A levels decreased by 56.2% in patients undergoing surgery. CONCLUSIONS: Gastric antrectomy is the most efficacious treatment for Type 1 gastric carcinoid, leading to a significant reduction in serum gastrin levels and regression of carcinoid tumors.