Enterochromaffin-like Cell Tumors Research Articles

Carcinogenicity assessment of tegoprazan in Sprague-Dawley (Crl:CD) rats and ICR (Crl:CD1) mice

Tegoprazan is a novel potassium-competitive acid blocker (P-CAB) that reversibly inhibits the proton pump in gastric parietal cells and has been approved for the treatment of acid-related diseases in Korea. This study aimed to evaluate the carcinogenic potential of tegoprazan in Sprague-Dawley rats and CD-1 mice. Tegoprazan was administered daily by oral gavage to rats for up to 94 weeks and mice for up to 104 weeks. Evidence of carcinogenic potential of tegoprazan was identified in rats only and was limited to benign and/or malignant neuroendocrine cell tumors at exposures >7-fold of the recommended human dose. Glandular stomach findings were considered secondary to the expected pharmacology of tegoprazan, characterized by their location in the fundic and body regions of the stomach. Overall, tegoprazan induced gastric enterochromaffin-like (ECL) cell tumors in SD rats, but did not produce any treatment-related statistically significant increase in the incidence of neoplasms relevant to humans when administered to SD rats and CD-1 mice by gavage at doses up to 300 and 150 mg/kg/day, respectively. Gastric ECL cell tumors are thought to be induced by the exaggerated indirect pharmacological effect of tegoprazan, similar to that reported for proton pump inhibitors (PPIs) and other P-CABs.

Particular endoscopic presentation of multiple gastric ECLomas

66-year-old woman with no significant pathological history is admitted for etiologic assessment of anemia. It is an iron deficiency microcytic anemia with hemoglobin at 9.8g/dL. An upper digestive endoscopy showed multiple fundic polypoid lesions of variable size measuring more than 10mm, including a subcardial lesion measuring 20mm (Figure 1&2). With the presence of other antrals centimetrics polypoids lesions. The anatomopathological examination of the lesions is in favor of ECL (enterochromaffin like) cell carcinoids. Fundic biopsy revealed fundic atrophy consistent with Biermer's disease. The biological assessment showed a collapsed vitamin B12 level with the presence of anti parietal cell antibodies. The treatment is based on injectable iron infusions, vitamin B12 injections and taking proton pump inhibitors. supracentimetric polypoid lesions were resected endoscopically with regular endoscopic control of other small lesions. Gastric neuroendocrine tumors form a heterogeneous group, very largely dominated by tumors derived from so-called enterochromaffin-like (ECL) cells, endocrine cells specialized in the secretion of histamine and located within the fundic mucosa, at the deep part of the glands [1]. The vast majority of ECL cell tumors occur in a context of hypergastrinemia. It is most often a hypergastrinemia secondary to achlorhydria induced by chronic atrophic gastritis affecting the fundic mucosa (especially in the context of Biermer's disease). Endoscopically, gastric neuroendocrine tumors appear as multiple small polypoid lesions of less than 1 cm in size. Therapeutically, simple monitoring is recommended for ECLomas < 1 cm in size. In case of size > 1 cm, an endoscopic mucosectomy is sufficient if the submucosa is undamaged. Otherwise, ECLomas are treated by local resection associated with antrectomy.

S3718 A Case of Chronic Atrophic Gastritis Leading to Gastric Neuroendocrine Tumor

Introduction: Neuroendocrine tumors are a rare cancer type that form in neuroendocrine cells. They can occur anywhere in the body, most commonly found in the gastrointestinal tract, bronchopulmonary system, and pancreas. Gastrointestinal NETs (GNETs) are slow-growing tumors that arise from enterochromaffin-like cell tumors and contain chromogranin, synaptophysin, and neuron-specific enolase and can develop throughout the GI tract. Case Description/Methods: 73-year-old female with a prior history of chronic atrophic gastritis with initial presentation of Iron deficiency anemia who underwent EGD and Colonoscopy. Was found to have small bleeding gastric mass on EGD, revealed Type 1 gastric carcinoid tumor on biopsy. She had a (+) anti-parietal cell antibody titer as well as elevated gastrin level. She underwent a partial gastrectomy, the pathology revealed a well-differentiated NET. Her chromogranin level was much higher compared to post surgery levels. It was recommended to continue with only yearly endoscopic surveillance. Discussion: NET features both nerve cells and endocrine cells. Most of the NETs are hormone-secreting and others are associated with hereditary genetic syndromes like multiple endocrine neoplasia type 1 and neurofibromatosis type 1. Although in roots of carcinogenesis, mutation and genetic changes play a central role, hormones can certainly predispose or amplify the process of cancer formation. GNETs have been classified into three different subtypes based on clinical characteristics: Type I, II and III GNETs. Type I GNETs are related to chronic gastritis with hypergastrinemia and enterochromaffin-like cell hyperplasia. Although GNETs remain rare tumors, the incidence of Type 1-GNETs has increased significantly, accounting for about 70-80% of all diagnosed GNETs. This case demonstrates importance of surveillance for NET in patients with chronic atrophic gastritis due to increasing prevalence and incidence. Once diagnosed, endoscopic surveillance and endoscopic removal are reasonable approaches in a surveillance strategy. The optimal interval of such interventions remains to be determined. It is important to emphasize using cost effective yet efficient diagnostic modality in order to identify lesions with predilection for G-NETS early in its course for better outcomes and treatment. As these tumors become better characterized and recognized in the future, societal guidelines for surveillance for GNETs associated with chronic atrophic gastritis will be of benefit.

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

Gastric enterochromaffin-like cell (ECL) tumours can occur in patients with multiple endocrine neoplasia type 1 (MEN1), especially in those affected by Zollinger Ellison syndrome (ZES). Since the prevalence of ECL lesions is not well defined yet, the present study evaluated the presence and extent of ECL lesions in MEN1 patients with and without ZES. Multiple endocrine neoplasia type 1 patients being part of a regular screening program (2014-2018) underwent gastroduodenoscopies with biopsies of the stomach and determination of serum gastrin and chromogranin A levels. Haematoxylin- and immunostaining with chromogranin A, gastrin and VMAT I and II (vesicular monoamine transporter I and II) of the biopsies were performed. Thirty-eight MEN1 patients, of whom 16 (42%) were diagnosed and treated earlier for ZES, were analysed. In ten of 16 (62.5%) ZES patients, a locally scattered, mixed image of diffuse, linear and micronodular mild hyperplasia was present. In addition, two of these patients (13%) showed small (max 1.5mm in size) intramucosal ECL tumours. Neither ECL changes, nor tumours were found in MEN1 patients without ZES (n=22). In MEN1/ZES patients, the median serum gastrin level was significantly elevated compared to MEN1 patients without ZES (206pg/ml vs. 30.5pg/ml, p<.001). A subgroup analysis of the serum gastrin and chromogranin A levels of MEN1/ZES patients with or without ECL hyperplasia did not show significant differences (gastrin level: p=.302, chromogranin A: p=.464). Enterochromaffin-like cell hyperplasia and gastric carcinoids occur only in MEN1 patients with ZES, but less frequently than reported.

Chloroacetanilide herbicide-induced rat enterochromaffin cell tumors: a case study within the context of the IPCS framework, for analyzing the relevance of a cancer mode of action for humans

The WHO International Programme on Chemical Safety (IPCS) framework for analyzing the relevance of a cancer mode of action (MoA) for humans (IPCS cancer-HRF) is an application to assess human relevance of tumorigenic hazards found through rodent bioassays. The chloroacetanilide herbicides, butachlor and alachlor, induced enterochromaffin-like (ECL) cell tumors in rat stomachs, at the highest doses. This study analyzed the human relevance of this tumor by applying the IPCS cancer-HRF using published data. In a postulated MoA, early key events (KEs) included decreased mucosal thickness in the fundic region, due to reduced parietal cells. The following KEs included increased pH of gastric acid and hypergastrinemia, leading to enhanced cell proliferation and hyperplasia, and resulting in the outcome of an ECL cell tumor. The data showed consistencies in dose-response and temporal concordance with the KEs and specificity in the tumor response, providing strengthened evidence of the KEs. While the early KE was not the same, similar MoAs have already been established for omeprazole and ciprofloxacin. The integrated data indicated that the postulated MoAs were biologically plausible. Alternative MoAs were excluded.. Based on sufficient evidence, an MoA was established in rats. When addressing chemically inducible MoAs of human relevance, KEs of hypergastrinemia and trophic ECL cell hyperplasia were judged to not be qualitatively and quantitatively plausible in humans. The MoA in rats is unlikely to be present in humans; however, the potential effects on parietal cells cannot be excluded. Thus, the IPCS cancer-HRF is very useful for assessing human relevance.

Neuroendocrine pathology of the stomach: the Parma contribution.

The current knowledge on gastric neuroendocrine pathology essentially developed in the last four decades. The historical evolution of the concepts and of the relevant clinical implications is described from the perspective of a group actively participating in this research domain. The histamine-producing enterochromaffin-like (ECL) cells have been recognized as the leading cell type involved in the most significant alterations of gastric neuroendocrine cells. The trophic stimulus exerted by circulating gastrin has been demonstrated to have a crucial role on proliferative changes of ECL cells through a sequence of hyperplasia-dysplasia-neoplasia described by Solcia et al. (Digestion 41:185-200,1988). The development of ECL cell tumors in rats treated with toxicological doses of inhibitors of gastric acid secretion prompted appropriate anatomoclinical investigations proving the lack of tumor risk in humans when therapeutic dosages of the drugs are used. Moving from the comprehensive concept of gastric carcinoid, different types of neuroendocrine tumors have been identified in the stomach with substantial variations in prognosis and treatment options. In general, ECL cell tumors developed in hypergastrinemic conditions were found to behave better than those originating outside the setting of hormonal stimulation. Pathological features highly predictive of patient survival have been described. The genetic changes involved in tumor development and progression have revealed substantial overlapping with those of neuroendocrine tumors of other foregut derivatives (i.e., pancreas, duodenum, lung) delineating a family of neuroendocrine tumors genetically distinct from those of the distal parts of the digestive system.

Case 200: Gastric Enterochromaffinlike Cell Tumors in a Patient with Type 1 Multiple Endocrine Neoplasia

History A 55-year-old man presented with chronic epigastric pain lasting for about 1 year and without fever or vomiting. The abdomen was soft and tender at physical examination. Laboratory tests revealed unremarkable liver function, normal hemoglobin level, and normal amylase level. White blood cell count was normal, and there was no inflammatory syndrome. The patient's medical history included pancreatic gastrinoma resected by means of left pancreatectomy 31 years before, hyperparathyroidism treated with subtotal parathyroidectomy 24 years before, and a slowly growing lung mass known for 9 years. Esophagogastroduodenoscopy was performed because of a suspected gastroduodenal ulcer. The results showed numerous small (<10 mm) gastric and duodenal ulcers and multiple 10-15-mm polypoid gastric masses. Contrast material-enhanced dual-phase multidetector row computed tomography (CT) of the chest and abdomen was performed with a 64-section CT scanner (LightSpeed VCT; GE Healthcare, Milwaukee, Wis). Technical parameters for CT were as follows: pitch, 0.98; section thickness and reconstruction interval, 1.25 mm; 120 kVp; and variable milliamperage determined by x-, y-, and z-axis dose modulation. After an unenhanced abdominal scan, iobitridol, a nonionic iodinated contrast agent containing 350 mg of iodine per milliliter (Xenetix 350; Guerbet, Aulnay-sousbois, France), was administered intravenously through a 16-18-gauge catheter. A 120-mL dose of the contrast agent was injected via an antecubital vein at a rate of 4 mL/sec. No oral contrast medium was administered. After preliminary unenhanced abdominal scanning, arterial and portal venous phase acquisitions were obtained 45 and 80 seconds after initiation of contrast medium injection.

Consensus Diagnoses and Mode of Action for the Formation of Gastric Tumors in Rats Treated with the Chloroacetanilide Herbicides Alachlor and Butachlor

A panel of pathologists (Panel) was formed to evaluate the pathogenesis and human relevance of tumors that developed in the fundic region of rat stomachs in carcinogenicity and mechanistic studies with alachlor and butachlor. The Panel evaluated stomach sections stained with hematoxylin and eosin, neuron-specific enolase, and chromogranin A to determine the presence and relative proportion of enterochromaffin-like (ECL) cells in the tumors and concluded all tumors were derived from ECL cells. Biochemical and pathological data demonstrated the tumor formation involved a nongenotoxic threshold mode of action (MOA) initially characterized by profound atrophy of the glandular fundic mucosa that affected gastric glands, but not surface epithelium. This resulted in a substantial loss of parietal cells and a compensatory mucosal cell proliferation. The loss of parietal cells caused a marked increase in gastric pH (hypochlorhydria), leading to sustained and profound hypergastrinemia. The mucosal atrophy, together with the increased gastrin, stimulated cell growth in one or more ECL cell populations, resulting in neoplasia. ECL cell autocrine and paracrine effects led to dedifferentiation of ECL cell tumors. The Panel concluded the tumors develop via a threshold-dependent nongenotoxic MOA, under conditions not relevant to humans.

Gastric carcinoid in a patient infected withHelicobacter pylori: A new entity?

There are four types of gastric carcinoid tumors, classified according to their histology and malignant potential. Only a few cases of carcinoid tumors in patients infected with Helicobacter pylori (H. pylori) have been reported so far. We report a patient infected with H. pylori presenting with a small solitary gastric carcinoid tumor with very low proliferative rate and normal gastrin levels. The tumor was endoscopically removed and the patient received an eradication therapy against H. pylori. No signs of metastatic disease have been found so far during more than 3 year of follow-up. Infection with H. pylori may cause chronic gastritis with normal or elevated gastrin levels, leading to the development of gastric carcinoids by mechanisms unrelated to gastrin. Enterochromaffin-like cell tumors related to a chronic H. pylori infection may be considered as a distinct type of gastric carcinoid tumors.

The CCK 2 receptor antagonist, YF476, inhibits Mastomys ECL cell hyperplasia and gastric carcinoid tumor development

YF476 is a potent and highly selective cholecystokin 2 (CCK 2) receptor antagonist of the benzodiazepine class. It inhibits gastric neuroendocrine enterochromaffin-like (ECL) cell secretion, proliferation and spontaneous formation of gastric neuroendocrine tumors (carcinoids) in cotton rats. The Mastomys rodent species exhibits a genetic predisposition to gastric ECL neuroendocrine tumor formation which can be accelerated by acid suppression and induction of hypergastrinemia. In this respect, it mimics the human condition of atrophic gastritis, hypergastrinemia and gastric carcinoid development. We investigated whether YF476 could inhibit acid suppression-induced ECL cell hyperplasia and neoplasia in this model. In addition, we examined whether YF476 could reverse established ECL cell hyperplasia and neoplasia. Targeting the CCK 2 receptor during Loxtidine-induced hypergastrinemia resulted in a reduction in ECL cell secretion (plasma and mucosal histamine, and histidine decarboxylase ( HDC) transcripts, p < 0.05) and proliferation (numbers of HDC-positive cells, connective tissue growth factor ( CTGF) and cyclin D1 transcription). This was associated with a decrease in ECL cell hyperplasia and a 60% reduction in gastric ECL cell microcarcinoid (tumors < 0.3 mm in size) formation. YF476 inhibited ECL cell neoplasia (gastric carcinoid) in animals with hyperplasia, inhibited the formation of ECL cell tumors when co-administered with Loxtidine and reversed the growth and developement of gastric ECL cell carcinoids in long-term acid suppressed Mastomys. Variable importance analysis using a logistic multinomial regression model indicated the effects of YF476 were specific to the ECL cell and alterations in ECL cell function reflected inhibition of transcripts for HDC, Chromogranin A ( CgA), CCK 2 and the autocrine growth factor, CTGF. We conclude that specifically targeting the CCK 2 receptor inhibits gastrin-mediated ECL cell secretion and ECL cell proliferation and tumor development in vivo.

Carcinogenic Hypergastrinemia: Signet-Ring Cell Carcinoma in a Patient with Multiple Endocrine Neoplasia Type 1 with Zollinger-Ellison’s Syndrome

Gastric neuroendocrine tumors are rare neoplasms that originate from gastric enterochromaffin-like (ECL) cells in the oxyntic mucosa. Gastrin and its derivates have been reported to regulate epithelial cell proliferation, migration, and differentiation. Mutations in the epithelial cadherin (E-cadherin) gene have been shown to be associated with the occurrence of diffuse gastric carcinomas in affected families. In this study we investigated the histopathological and molecular findings in the gastrointestinal wall of a patient with multiple endocrine neoplasia type 1 with malignant duodenal gastrinoma and multiple gastric ECL cell tumors, who additionally developed a signet-ring cell carcinoma of the stomach. Biopsies from the gastrointestinal tract of a patient with multiple endocrine neoplasia type 1 were immunostained for vesicular monoamine transporter-2 and E-cadherin. Nonamidated gastrin products were measured in the serum of the patient using antibodies that react with progastrin, Gly-extended, and amidated gastrins. Genetic analyses were performed to exclude germ-line mutations within the E-cadherin gene. Immunohistochemical studies of gastric ECL cell tumors showed a largely diminished E-cadherin expression in comparison to gastric surface mucosa cells and a loss of E-cadherin expression in the cells of the signet-ring carcinoma. Detailed biochemical measurements revealed progastrin concentrations that were approximately 20%, and Gly-gastrin concentrations that were approximately 10% the amidated gastrin concentrations in plasma. Molecular analyses revealed no E-cadherin germ-line mutation. Our immunohistochemical studies might suggest that the gastrinoma-associated excessive progastrin tissue concentrations led to diminished expression of E-cadherin within the gastric mucosa and promoted tumor development of a signet-ring cell carcinoma.

Prognostic value of immunohistochemistry in gastric neuroendocrine (carcinoid) tumors

Three subtypes of enterochromaffin-like cell tumors (carcinoids) have been described: type I, associated with chronic atrophic gastritis; type II, multiple endocrine neoplasia 1 and Zollinger-Ellison syndrome; and type III, sporadic tumors. (i) To investigate the immunoexpression of Ki-67, p53 and Bcl-2 proteins in enterochromaffin-like cell (carcinoid) tumors and (ii) to evaluate the prognostic value of these markers. Fifty-four samples from 21 patients with gastric carcinoid tumors were sectioned and immunostained using avidin-biotin peroxidase method. The mean age was 62.2+/-11.4 years (36-83 years-old) and 13 (61.9%) were women. Type I lesions were detected in 61.9% and type III in 38.1%. Tumors were single in 10 (47.6%) and were multiple and/or multicentric in 11 (52.4%). Nuclear p53 immunoreactivity was observed in 6/21 patients (28.6%), and all of them were type III tumors (6/8), compared with no p53 expression in type I (0/13), P=0.0002. p53 expression was also associated with high degree of cell proliferation (Ki-67-positive nuclear cells), P=0.00001. Bcl-2 expression was either unreactive or weakly positive in all tumor lesions. The mean follow-up period was 50.4 months (SD=45.2), varying from 6 to 144 months. Overall survival time of patients with positive p53 expression and high proliferative rate was significantly lower than that of negative patients (14.4 vs 123 months, P=0.0007). (i) p53 immunoexpression associated with high proliferative rate was useful to distinguish between type I and type III gastric carcinoid tumors and (ii) these markers were able to predict a shorter survival.

Effects of 5 years of treatment with rabeprazole or omeprazole on the gastric mucosa

Prolonged gastric acid suppression leads to hypergastrinaemia, which promotes hyperplasia of the enterochromaffin-like (ECL) cells of the oxyntic mucosa. The objective was to determine the effects of 5 years of treatment with rabeprazole or omeprazole on the gastric mucosa. Two hundred and forty-three patients received rabeprazole (20 mg or 10 mg) or omeprazole (20 mg) once daily for up to 5 years, for gastro-oesophageal reflux disease and 51% completed the whole 5 year period. Gastric biopsy specimens were taken and examined for gastritis, Helicobacter pylori infection, and ECL cell status. H. pylori infection in the gastric corpus was more common than in the antrum, and remained constant, whereas antral H. pylori infection became less common as the study progressed. H. pylori infection was a highly significant predictor of higher gastritis scores, which were similar among the three treatment groups. ECL cell hyperplasia occurred in a minority of patients, and was associated with serum gastrin concentrations. No ECL cell dysplasia or tumours were observed. There were no significant differences among the treatment groups in gastritis or ECL cell hyperplasia grades. This study has confirmed the link between ECL cell hyperplasia and elevated serum gastrin concentrations, but has found no evidence that this progresses to high grades of hyperplasia during 5 years of treatment with rabeprazole or omeprazole.

Precursor Lesions in Patients With Multiple Endocrine Neoplasia Type 1--Associated Duodenal Gastrinomas

The identification of precursor lesions has a great impact on the understanding of tumorigenesis. Precursor lesions of endocrine tumors are known to occur in the setting of the MEN1 syndrome. The aim of this study was to test the hypothesis that MEN1-associated duodenal gastrinomas originate from diffuse preneoplastic gastrin cell changes. Precursor lesions may precede the development of duodenal gastrinomas because, in contrast to sporadic gastrinomas, these tumors are usually multiple. The distribution of endocrine cells in the nontumorous duodenal tissue was analyzed qualitatively and quantitatively for 25 patients operated on for a duodenal gastrinoma. MEN1 status was assessed clinically and by polymerase chain reaction-based mutational analysis. Fourteen of 25 patients with gastrinoma had proliferative, hyperplastic lesions consisting of gastrin cells in the nontumorous duodenal mucosa, similar to the gastric enterochromaffin-like cell lesions observed in chronic atrophic gastritis. All patients with Zollinger-Ellison syndrome with proven MEN1 had such proliferative gastrin cell lesions, and all patients with Zollinger-Ellison syndrome without precursor lesions were MEN1 negative. Duodenal gastrinomas in MEN1, but not sporadic duodenal gastrinomas, are associated with proliferative gastrin cell changes within the nontumorous mucosa. It is likely that these lesions precede the development of MEN1-associated duodenal gastrinomas.

Global expression analysis of ECL cells in Mastomys natalensis gastric mucosa identifies alterations in the AP-1 pathway induced by gastrin-mediated transformation

Enterochromaffin-like (ECL) cell hyperplasia and then irreversible neoplasia can be generated in the African rodent Mastomys natalensis using the H2 receptor blocker, loxtidine, for 8-16 wk. We used a GeneChip approach complemented by standard technologies to identify gene expression alterations in the gastric mucosa during gastrin-mediated ECL cell transformation. Gastric mucosa (mucosal scrapping) and ECL cell-enriched fractions were obtained from untreated Mastomys (controls) and from animals treated with loxtidine for 8 wk (hyperplasia). Tumor ECL cells were obtained by hand-dissection of gastric ECL cell nodules from animals treated with loxtidine for >16 wk and from a spontaneously developed ECL cell tumor. RNA was isolated, examined on rat U34A GeneChips, and comparison analysis was performed to identify altered gene expression. Alterations in gene expressions were examined further by immunohistochemistry, quantitative RT-PCR (Q-RT-PCR), sequencing and Western blot. GeneSpring analysis demonstrated alterations in few genes (<20) in hyperplastic and tumor mucosa. The histamine H1 receptor was consistently increased in proliferating mucosa. This gene change was confirmed by Q-RT-PCR. Other genes showing alterations included neural-(chromogranin A and somatostatin), cell-cycle-, and AP-1-associated genes. Immunostaining confirmed alterations in neural markers. Cluster analysis of ECL cell-enriched samples demonstrated that c-fos and junD were differently regulated. Q-RT-PCR and Western blot in prospectively collected gastric mucosal samples confirmed the differential expression of Fos and Jun. The negative regulators of AP-1, JunD, and Menin were decreased in tumor mucosa. A missense of unknown function was noted in the menin gene. Hypergastrinemia in an animal model of gastric carcinoids differentially altered the histamine type 1 receptor and gene expression and protein composition of AP-1. These results suggest that expression of this receptor and an altered composition of AP-1 with a loss of inhibition play a role in ECL cell transformation.

Enterocromaffin-like cell tumor induced by Helicobacter pylori infection in Mongolian gerbils.

Gastric carcinoids are strongly associated with chronic atrophic gastritis A, and it is suggested that hypergastrinemia plays a critical role in development of gastric carcinoids. Since Helicobacter pylori infection causes hypergastrinemia, it is held that H. pylori infection produces gastric carcinoids. We followed the histological changes of H. pylori-infected stomachs of Mongolian gerbils for a long time. Five-week-old-male Mongolian gerbils were infected with H. pylori ATCC 43504 with cagA gene, expressing vacuolating cytotoxin. Determination of the serum gastrin and histopathological examination of the stomach at 6, 12, 18, and 24 months after H. pylori inoculation was studied and compared with uninfected animals. In infected animals, the gastric carcinomas appeared 18 and 24 months after infection. Endocrine cell dysplasias and carcinoids with marked atrophic gastritis of the oxyntic mucosa were observed in the infected animals 24 months after H. pylori inoculation. The serum gastrin level in the infected group increased from an average of 86.2 pg/ml at the beginning of the study to an average of 498 pg/ml and 989 pg/ml at 18 and 24 months after infection, respectively. These changes in the serum gastrin levels were significant compared with uninfected controls that showed no changes. H. pylori infection caused not only gastric carcinomas but also enterochromaffin-like cell tumors in Mongolian gerbils, due to hypergastrinemia. This model is thought to be useful to study the relationship between hypergastrinemia and gastric carcinoids.

PACAP mediates the neural proliferative pathway of Mastomys Enterochromaffin-like cell transformation

Background and aim: Pituitary adenylate-cyclase activating peptide (PACAP) is a more potent proliferative agent than gastrin for rat enterochromaffin-like (ECL) cell proliferation in vitro. The role of this neurotransmitter during gastrin-mediated ECL cell tumor formation and gastrin-autonomous ECL cell neoplasia is unknown. Methods and results: ECL cell transformation was induced in the Mastomys using 16 wk H 2 receptor blockade of acid inhibition. Examination of the epithelial fundic mucosa demonstrated that PACAP-immunoreactivity significantly increased in the tumor mucosa compared to the naı̈ve stomach, and was associated with ECL cells. Naı̈ve and tumor ECL cells were then purified (∼95%) from Mastomys and the presence of all three PACAP/VPAC receptor subtypes was demonstrated by polymerase chain-reaction amplification. Thereafter, cells were maintained in short-term (48 h) primary cultures. PACAP significantly ( p<0.05) increased 24 h bromo-deoxyuridine uptake (∼4-fold) in both cell types with estimated EC 50 values of ∼4×10 −16 M and ∼2×10 −16 M, respectively. Specific receptor antagonists (PAC 1/VPAC 1) of PACAP competitively inhibited these proliferative effects in naı̈ve cells. Oligonucleotide antisense directed against PAC 1 significantly inhibited PACAP-stimulated DNA synthesis by ∼85% ( p<0.05) in tumor cells. Conclusion: PACAP is a potent and effective modulator of ECL cell proliferation. The expression of this neuropeptide and its receptors, particularly PAC 1, suggest the existence of a neural regulatory pathway of ECL cell proliferation and transformation.

Enterochromaffin-like (ECL) cells express amphiphysin in addition to neuronal and muscle cells in the rat castric corpus

Background. Human and rat fundic mucosa contain Enterochromaffinlike(ECL) cells. We have previously shown that these cells undergo apoptosis in the presence of TNF-a, a cytokine that is released during H. pylori infection in the gastric mucosa. Of further interest is basic FGF which is detected in ECL cell tumors. The aim of our current study was to elucidate the mechanisms of TNF-a induced apoptotis in ECL-cells and the role of bFGF during this reponse. MethodslResults. ECL-cells were isolated from rat fundic mucosa to a purity> 90% and cultured up to 24 hr. Western Blotting showed a strong signal from unphosphorylated lKBa at 0 min. After 5 min, the signal was decreased and after 10 min, unphosphorylated lKBa-was no longer detectable, indicating that IKBa was strongly phosphorylated, which in tum leads to the activation of NFKB. To determine NFKB-activation more directly, we performed electromobility-shift assays (EMSA) using cell extracts pretreated with vehicle for I hr, then treated with TNF-a (25 ng/mL) or vehicle for another hour. The EMSAs revealed a specific activation of the NFKB subunits p50 and p65. In order to investigate the functional role of NFKB in the mediation of pro-apoptotic TNF-a effects, we measured ECL-cell apoptosis (programed cell death) after preincubation (I hr) with the specific NFKB-inhibitors MGl32 (5 mM) and PSI (6 mM) and subsequent incubation with TNF-a (25 ng/mL, I hr). Cells incubated without inhibitors and/or TNF-a served as controls. Using the TUNEL technique, TNF-a was found to cause apoptosis in 16% ofECL cells compared to a basal rate of6%. MGI32 and PSI alone did not induce apoptosis (total of 5-8% of ECL cells), but were able to inhibit TNF-a-induced apoptosis completely. For MG132, these results were repeated using an ELISA-assay based upon the detection of nucleosomes which also showed complete inhibition ofTNF-a effects. The observations were verified using the EMSA technique mentioned above. To elucidate the role of basic FGF, we tested bFGF effects on TNF-a induced apoptosis. Using the ELISA, we found that bFGF at 10-100 ng/mL completely blocked TNF-a induced cell death. Conclusion. TNF-a induced apoptosis of ECL cells is mediated by phosphorylation of IKBa and subsequent activation of NFKB. bFGF inhibits TNF-a induced ECL cell death, which may also playa role for the persistence of ECL cells during chronic gastric inflammation (DFG Pr 41112-2).

TNF-a-associated apoptosis in rat gastric enterochromaffin-like cells is mediated by NFKB and can be antagonized by BFGF

Background. Human and rat fundic mucosa contain Enterochromaffinlike(ECL) cells. We have previously shown that these cells undergo apoptosis in the presence of TNF-a, a cytokine that is released during H. pylori infection in the gastric mucosa. Of further interest is basic FGF which is detected in ECL cell tumors. The aim of our current study was to elucidate the mechanisms of TNF-a induced apoptotis in ECL-cells and the role of bFGF during this reponse. MethodslResults. ECL-cells were isolated from rat fundic mucosa to a purity> 90% and cultured up to 24 hr. Western Blotting showed a strong signal from unphosphorylated lKBa at 0 min. After 5 min, the signal was decreased and after 10 min, unphosphorylated lKBa-was no longer detectable, indicating that IKBa was strongly phosphorylated, which in tum leads to the activation of NFKB. To determine NFKB-activation more directly, we performed electromobility-shift assays (EMSA) using cell extracts pretreated with vehicle for I hr, then treated with TNF-a (25 ng/mL) or vehicle for another hour. The EMSAs revealed a specific activation of the NFKB subunits p50 and p65. In order to investigate the functional role of NFKB in the mediation of pro-apoptotic TNF-a effects, we measured ECL-cell apoptosis (programed cell death) after preincubation (I hr) with the specific NFKB-inhibitors MGl32 (5 mM) and PSI (6 mM) and subsequent incubation with TNF-a (25 ng/mL, I hr). Cells incubated without inhibitors and/or TNF-a served as controls. Using the TUNEL technique, TNF-a was found to cause apoptosis in 16% ofECL cells compared to a basal rate of6%. MGI32 and PSI alone did not induce apoptosis (total of 5-8% of ECL cells), but were able to inhibit TNF-a-induced apoptosis completely. For MG132, these results were repeated using an ELISA-assay based upon the detection of nucleosomes which also showed complete inhibition ofTNF-a effects. The observations were verified using the EMSA technique mentioned above. To elucidate the role of basic FGF, we tested bFGF effects on TNF-a induced apoptosis. Using the ELISA, we found that bFGF at 10-100 ng/mL completely blocked TNF-a induced cell death. Conclusion. TNF-a induced apoptosis of ECL cells is mediated by phosphorylation of IKBa and subsequent activation of NFKB. bFGF inhibits TNF-a induced ECL cell death, which may also playa role for the persistence of ECL cells during chronic gastric inflammation (DFG Pr 41112-2).

Morphological, molecular, and prognostic aspects of gastric endocrine tumors.

This paper aims at describing the neuroendocrine cell growths of the gastric mucosa and their pathogenesis. In the corpus-fundus mucosa, gastric neuroendocrine nontumor growths are mostly represented by hyperplastic and, more rarely, dysplastic enterochromaffin-like (ECL) cell changes, while hyperplasia of gastrin-producing (G) cells and, rarely, of somatostatin-producing (D) cells are reported in the antral mucosa. The large majority of gastric neuroendocrine tumors is made by benign, gastrin-dependent, well-differentiated ECL cell growths arising in a background of chronic atrophic gastritis (type I) or, more rarely, associated with type I multiple endocrine neoplasia (MEN I) and Zollinger-Ellison (ZE) syndromes (type II). Rare, aggressive, frequently metastatic, well-differentiated gastric neuroendocrine tumors are gastrin-independent and arise as sporadic lesions in the absence of specific gastric pathology (type III). Poorly differentiated neuroendocrine carcinomas (PDEC) are rare, highly aggressive carcinomas. A central role for gastrin is postulated in the pathogenesis of well-differentiated type I and II ECL cell tumors with different possible genetic mechanisms. A more complex genetic background, independent of gastrin and possibly implicating altered function or mutation of p53 and other genes is highly suspected for the development of aggressive type III ECL cell carcinomas and PDECs.