Synergistic inhibitory effects of gastrin and histamine receptor antagonists on Helicobacter-induced gastric cancer

Spatial Variation of the Gastrointestinal Microbiota in Response to Long-Term Administration of Vonoprazan in Mice With High Risk of Gastric Cancer

BACKGROUND

Vonoprazan, a potassium-competitive acid blocker, is superior to traditional proton pump inhibitor (PPI) in acid suppression and has been approved in the treatment of acid-related disorders. Accumulating evidence suggest associations between PPI use and gut microbiota, yet the effect of vonoprazan on GI microbiota is obscure.

METHODS

Transgenic FVB/N insulin-gastrin (INS-GAS) mice as a model of gastric cancer (GC) were administered vonoprazan by gavage every other day for 12 weeks. Stomachs were evaluated by histopathology, Ki-67 proliferation index, and inflammatory cytokines. The mucosal and lumen microbiota from stomach, jejunum, ileum, cecum, and feces were detected using 16S rRNA gene sequencing.

RESULTS

Higher incidence of intestinal metaplasia and epithelial proliferation were observed in the vonoprazan group than that in the control mice. Vonoprazan also elevated the gastric expression of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6. Each mice comprised a unique microbiota composition that was consistent across different niches. The structure of GI microbiota changed dramatically after vonoprazan treatment with the stomach being the most disturbed segment. Vonoprazan administration shifted the gut microbiota toward the enrichment of pathogenic Streptococcus, Staphylococcus, Bilophila, and the loss of commensal Prevotella, Bifidobacterium, and Faecalibacterium. Interestingly, compared to the controls, microbial interactions were weaker in the stomach while stronger in the jejunum of the vonoprazan group.

CONCLUSIONS

Long-term vonoprazan treatment promoted gastric lesions in male INS-GAS mice, with the disequilibrium of GI microbiome. The clinical application of vonoprazan needs to be judicious particularly among those with high risk of GC.

Evaluation of the Differences in the Expression of Biogenic Amine-Related mRNAs and Proteins in Endometrioid Endometrial Cancer

Biogenic amines, such as adrenaline, noradrenaline, histamine, dopamine, and serotonin are important neurotransmitters that also regulate cell viability. Their detection and analysis are helpful in the diagnosis of many diseases, including cancer. The aim of this study was to determine the expression profile of the biogenic amine-related genes and proteins in endometrioid endometrial cancer compared to the control group. The material consisted of endometrial tissue samples and whole blood collected from 30 endometrioid endometrial cancer patients and 30 cancer-free patients. The gene expression was determined by the mRNA microarrays and validated by qRT-PCR. Protein levels were determined in the serum by the enzyme-linked immunosorbent assay (ELISA). Overexpression of histamine H1–H3 receptors and early growth response 1 and silencing of calmodulin, the histamine H4 receptor, and the dopamine D5 receptor have been reported in endometrioid endometrial cancer. The obtained results indicate disturbances in the signaling activated by histamine and dopamine receptors, which could potentially contribute to the progression of endometrioid endometrial cancer.

Hypergastrinemia Expands Gastric ECL Cells Through CCK2R+ Progenitor Cells via ERK Activation

BACKGROUND & AIMS

Enterochromaffin-like (ECL) cells in the stomach express gastrin/cholecystokinin 2 receptor CCK2R and are known to expand under hypergastrinemia, but whether this results from expansion of existing ECL cells or increased production from progenitors has not been clarified.

METHODS

We used mice with green fluorescent protein fluorescent reporter expression in ECL cells (histidine decarboxylase [Hdc]-green fluorescent protein), as well as Cck2r- and Hdc-driven Tamoxifen inducible recombinase Cre (Cck2r-CreERT2, Hdc-CreERT2) mice combined with Rosa26Sor-tdTomato (R26-tdTomato) mice, and studied their expression and cell fate in the gastric corpus by using models of hypergastrinemia (gastrin infusion, omeprazole treatment).

RESULTS

Hdc-GFP marked the majority of ECL cells, located in the lower third of the gastric glands. Hypergastrinemia led to expansion of ECL cells that was not restricted to the gland base, and promoted cellular proliferation (Ki67) in the gastric isthmus but not in basal ECL cells. Cck2r-CreERT2 mice marked most ECL cells, as well as scattered cell types located higher up in the glands, whose number was increased during hypergastrinemia. Cck2r-CreERT2⁺ isthmus progenitors, but not Hdc⁺ mature ECL cells, were the source of ECL cell hyperplasia during hypergastrinemia and could grow as 3-dimensional spheroids in vitro. Moreover, gastrin treatment in vitro promoted sphere formation from sorted Cck2r⁺Hdc^- cells, and increased chromogranin A and phosphorylated- extracellular signal-regulated kinase expression in CCK2R-derived organoids. Gastrin activates extracellular signal-regulated kinase pathways in vivo and in vitro, and treatment with the Mitogen-activated protein kinase kinase 1 inhibitor U0126 blocked hypergastrinemia-mediated changes, including CCK2R-derived ECL cell hyperplasia in vivo as well as sphere formation and chromogranin A expression in vitro.

CONCLUSIONS

We show here that hypergastrinemia induces ECL cell hyperplasia that is derived primarily from CCK2R⁺ progenitors in the corpus. Gastrin-dependent function of CCK2R⁺ progenitors is regulated by the extracellular signal-regulated kinase pathway.

Gastric Corpus Mucosal Hyperplasia and Neuroendocrine Cell Hyperplasia, but not Spasmolytic Polypeptide-Expressing Metaplasia, Is Prevented by a Gastrin Receptor Antagonist in H+/K+ATPase Beta Subunit Knockout Mice

Proton pump inhibitor use is associated with an increased risk of gastric cancer, which may be mediated by hypergastrinemia. Spasmolytic polypeptide-expression metaplasia (SPEM) has been proposed as a precursor of gastric cancer. We have examined the effects of the gastrin receptor antagonist netazepide (NTZ) or vehicle on the gastric corpus mucosa of H⁺/K⁺ATPase beta subunit knockout (KO) and wild-type (WT) mice. The gastric corpus was evaluated by histopathology, immunohistochemistry (IHC), in situ hybridization (ISH) and whole-genome gene expression analysis, focusing on markers of SPEM and neuroendocrine (NE) cells. KO mice had pronounced hypertrophy, intra- and submucosal cysts and extensive expression of SPEM and NE cell markers in the gastric corpus, but not in the antrum. Numerous SPEM-related genes were upregulated in KO mice compared to WT mice. NTZ reduced hypertrophia, cysts, inflammation and NE hyperplasia. However, NTZ neither affected expression of SPEM markers nor of SPEM-related genes. In conclusion, NTZ prevented mucosal hypertrophy, cyst formation and NE cell hyperplasia but did not affect SPEM. The presence of SPEM seems unrelated to the changes caused by hypergastrinemia in this animal model.

Insights into Effects/Risks of Chronic Hypergastrinemia and Lifelong PPI Treatment in Man Based on Studies of Patients with Zollinger-Ellison Syndrome

The use of proton pump inhibitors (PPIs) over the last 30 years has rapidly increased both in the United States and worldwide. PPIs are not only very widely used both for approved indications (peptic ulcer disease, gastroesophageal reflux disease (GERD), Helicobacter pylori eradication regimens, stress ulcer prevention), but are also one of the most frequently off-label used drugs (25–70% of total). An increasing number of patients with moderate to advanced gastroesophageal reflux disease are remaining on PPI indefinitely. Whereas numerous studies show PPIs remain effective and safe, most of these studies are <5 years of duration and little data exist for >10 years of treatment. Recently, based primarily on observational/epidemiological studies, there have been an increasing number of reports raising issues about safety and side-effects with very long-term chronic treatment. Some of these safety issues are related to the possible long-term effects of chronic hypergastrinemia, which occurs in all patients taking chronic PPIs, others are related to the hypo-/achlorhydria that frequently occurs with chronic PPI treatment, and in others the mechanisms are unclear. These issues have raised considerable controversy in large part because of lack of long-term PPI treatment data (>10–20 years). Zollinger–Ellison syndrome (ZES) is caused by ectopic secretion of gastrin from a neuroendocrine tumor resulting in severe acid hypersecretion requiring life-long antisecretory treatment with PPIs, which are the drugs of choice. Because in <30% of patients with ZES, a long-term cure is not possible, these patients have life-long hypergastrinemia and require life-long treatment with PPIs. Therefore, ZES patients have been proposed as a good model of the long-term effects of hypergastrinemia in man as well as the effects/side-effects of very long-term PPI treatment. In this article, the insights from studies on ZES into these controversial issues with pertinence to chronic PPI use in non-ZES patients is reviewed, primarily concentrating on data from the prospective long-term studies of ZES patients at NIH.

The Reduction in Gastric Atrophy after Helicobacter pylori Eradication Is Reduced by Treatment with Inhibitors of Gastric Acid Secretion

Background: Helicobacter pylori (H. pylori) eradication therapy may improve gastric atrophy and intestinal metaplasia, but the results of previous studies have not always been consistent. The aim of this study was to compare the histological changes of intestinal metaplasia and gastric atrophy among the use of acid-suppressing drugs after H. pylori eradication. Methods: A cohort of 242 patients who underwent successful eradication therapy for H. pylori gastritis and surveillance endoscopy examination from 1996 to 2015 was analyzed. Changes in the histological scores of intestinal metaplasia and atrophy according to drug use (proton-pump inhibitors (PPIs), H₂ receptor antagonists (H2RAs), and non-acid suppressant use) were evaluated in biopsies of the antrum and corpus using a generalized linear mixed model in all patients. Results: The mean follow-up period and number of biopsies were 5.48 ± 4.69 years and 2.62 ± 1.67 times, respectively. Improvement in the atrophy scores of both the antrum (p = 0.042) and corpus (p = 0.020) were significantly superior in patients with non-acid suppressant drug use compared with those of PPI and H2RA use. Metaplasia scores in both the antrum and corpus did not improve in all groups, and no significant differences were observed among groups in the antrum (p = 0.271) and corpus (p = 0.077). Conclusions: Prolonged acid suppression by PPIs or H2RAs may limit the recovery of gastric atrophy following H. pylori eradication.

Long-term use of proton-pump inhibitors and risk of gastric cancer: a review of the current evidence

Gastric cancer remains one of the leading cancers in the world with a high mortality, particularly in East Asia. Helicobacter pylori infection accounts for the majority of the noncardia gastric cancers by triggering gastric inflammation and subsequent neoplastic progression. Eradication of H. pylori can reduce, but not totally eliminate, subsequent risk of developing gastric cancer. Proton-pump inhibitors (PPIs) are one of the most widely prescribed medications worldwide. With their profound gastric-acid suppression, there are concerns about a possible carcinogenic role in gastric cancer, due to induced hypergastrinemia, gastric atrophy and bacterial overgrowth in the stomach. While randomized clinical trials to establish causality between long-term PPI use and gastric cancer are lacking, current evidence based on observational studies suggests PPIs are associated with an increased gastric cancer risk. However, opinions on causality remain divergent due to unmeasured and possible residual confounding in various studies. Our recent study has showed that even after H. pylori eradication, long-term PPI use is still associated with an increased risk of gastric cancer by more than twofold. Hence, long-term PPIs should be used judiciously after considering individual's risk-benefit profile, particularly among those with history of H. pylori infection. Further well-designed prospective studies are warranted to confirm the potential role of PPIs in gastric cancer according to baseline gastric histology and its interaction with other chemopreventive agents like aspirin, statins and metformin.

What We Know and What We Need to Know about Aromatic and Cationic Biogenic Amines in the Gastrointestinal Tract

Biogenic amines derived from basic and aromatic amino acids (B/A-BAs), polyamines, histamine, serotonin, and catecholamines are a group of molecules playing essential roles in many relevant physiological processes, including cell proliferation, immune response, nutrition and reproduction. All these physiological effects involve a variety of tissue-specific cellular receptors and signalling pathways, which conforms to a very complex network that is not yet well-characterized. Strong evidence has proved the importance of this group of molecules in the gastrointestinal context, also playing roles in several pathologies. This work is based on the hypothesis that integration of biomedical information helps to reach new translational actions. Thus, the major aim of this work is to combine scientific knowledge on biomolecules, metabolism and physiology of the main B/A-BAs involved in the pathophysiology of the gastrointestinal tract, in order to point out important gaps in information and other facts deserving further research efforts in order to connect molecular information with pathophysiological observations.

Blocking H1/H2 histamine receptors inhibits damage/fibrosis in Mdr2-/- mice and human cholangiocarcinoma tumorigenesis

Primary sclerosing cholangitis (PSC) patients are at risk of developing cholangiocarcinoma (CCA). We have shown that (1) histamine increases biliary hyperplasia through H1/H2 histamine receptors (HRs) and (2) histamine levels increase and mast cells (MCs) infiltrate during PSC and CCA. We examined the effects of chronic treatment with H1/H2HR antagonists on PSC and CCA. Wild-type and multidrug-resistant knockout (Mdr2-/- ) mice were treated by osmotic minipumps with saline, mepyramine, or ranitidine (10 mg/kg body weight/day) or a combination of mepyramine/ranitidine for 4 weeks. Liver damage was assessed by hematoxylin and eosin. We evaluated (1) H1/H2HR expression, (2) MC presence, (3) L-histidine decarboxylase/histamine axis, (4) cholangiocyte proliferation/bile duct mass, and (5) fibrosis/hepatic stellate cell activation. Nu/nu mice were implanted with Mz-ChA-1 cells into the hind flanks and treated with saline, mepyramine, or ranitidine. Tumor growth was measured, and (1) H1/H2HR expression, (2) proliferation, (3) MC activation, (4) angiogenesis, and (5) epithelial-mesenchymal transition (EMT) were evaluated. In vitro, human hepatic stellate cells were evaluated for H1HR and H2HR expression. Cultured cholangiocytes and CCA lines were treated with saline, mepyramine, or ranitidine (25 μM) before evaluating proliferation, angiogenesis, EMT, and potential signaling mechanisms. H1/H2HR and MC presence increased in human PSC and CCA. In H1/H2HR antagonist (alone or in combination)-treated Mdr2-/- mice, liver and biliary damage and fibrosis decreased compared to saline treatment. H1/H2HR antagonists decreased tumor growth, serum histamine, angiogenesis, and EMT. In vitro, H1/H2HR blockers reduced biliary proliferation, and CCA cells had decreased proliferation, angiogenesis, EMT, and migration. Conclusion: Inhibition of H1/H2HR reverses PSC-associated damage and decreases CCA growth, angiogenesis, and EMT; because PSC patients are at risk of developing CCA, using HR blockers may be therapeutic for these diseases. (Hepatology 2018).

Activation of Signal Transduction and Activator of Transcription 3 Signaling Contributes to Helicobacter-Associated Gastric Epithelial Proliferation and Inflammation

Background/Aim

Although IL-6-mediated activation of the signal transduction and activator of transcription 3 (STAT3) axis is involved in inflammation and cancer, the role of STAT3 in Helicobacter-associated gastric inflammation and carcinogenesis is unclear. This study investigated the role of STAT3 in gastric inflammation and carcinogenesis and examined the molecular mechanism of Helicobacter-induced gastric phenotypes.

Methods

To evaluate the contribution of STAT3 to gastric inflammation and carcinogenesis, we used wild-type (WT) and gastric epithelial conditional Stat3-knockout (Stat3^Δgec) mice. Mice were infected with Helicobacter felis and euthanized at 18 months postinfection. Mouse gastric organoids were treated with recombinant IL-6 (rIL-6) or rIL-11 and a JAK inhibitor (JAKi) to assess the role of IL-6/STAT3 signaling in vitro.

Results

Inflammation and mucous metaplasia were more severe in WT mice than in Stat3^Δgec mice. The epithelial cell proliferation rate and STAT3 activation were increased in WT mice. Application of rIL-6 and rIL-11 induced expression of intestinal metaplasia-associated genes, such as Tff2; this induction was suppressed by JAKi administration.

Conclusions

Loss of STAT3 signaling in the gastric mucosa leads to decreased epithelial cell proliferation, atrophy, and metaplasia in the setting of Helicobacter infection. Therefore, activation of STAT3 signaling may play a key role in Helicobacter-associated gastric carcinogenesis.

Gastrin stimulates a cholecystokinin-2-receptor-expressing cardia progenitor cell and promotes progression of Barrett's-like esophagus

Objective

The incidence of esophageal adenocarcinoma (EAC) is increasing, but factors contributing to malignant progression of its precursor lesion, Barrett's esophagus (BE), have not been defined. Hypergastrinemia caused by long-term use of proton pump inhibitors (PPIs), has been suggested as one possible risk factor. The gastrin receptor, CCK2R, is expressed in the cardia and upregulated in BE, suggesting the involvement of the gastrin-CCK2R pathway in progression. In the L2-IL-1β mouse model, Barrett's-like esophagus arises from the gastric cardia. Therefore, we aimed to analyze the effect of hypergastrinemia on CCK2R+ progenitor cells in L2-IL-1β mice.

Design

L2-IL-1β mice were mated with hypergastrinemic (INS-GAS) mice or treated with PPIs to examine the effect of hypergastrinemia in BE progression. CCK2R-CreERT crossed with L2-IL-1β mice were used to analyze the lineage progenitor potential of CCK2R+ cells. Cardia glands were cultured in vitro, and the effect of gastrin treatment analyzed. L2-IL-1β mice were treated with a CCK2R antagonist YF476 as a potential chemopreventive drug.

Results

Hypergastrinemia resulted in increased proliferation and expansion of Barrett's-like esophagus. Lineage tracing experiments revealed that CCK2R+ cells are long-lived progenitors that can give rise to such lesions under chronic inflammation. Gastrin stimulated organoid growth in cardia culture, while CCK2R inhibition prevented Barrett's-like esophagus and dysplasia.

Conclusions

Our data suggest a progression model for BE to EAC in which CCK2R+ progenitor cells, stimulated by hypergastrinemia, proliferate to give rise to metaplasia and dysplasia. Hypergastrinemia can result from PPI use, and the effects of hypergastrinemia in human BE should be studied further.

The cytoprotective protein clusterin is overexpressed in hypergastrinemic rodent models of oxyntic preneoplasia and promotes gastric cancer cell survival

The cytoprotective protein clusterin is often dysregulated during tumorigenesis, and in the stomach, upregulation of clusterin marks emergence of the oxyntic atrophy (loss of acid-producing parietal cells)-associated spasmolytic polypeptide-expressing metaplasia (SPEM). The hormone gastrin is important for normal function and maturation of the gastric oxyntic mucosa and hypergastrinemia might be involved in gastric carcinogenesis. Gastrin induces expression of clusterin in adenocarcinoma cells. In the present study, we examined the expression patterns and gastrin-mediated regulation of clusterin in gastric tissue from: humans; rats treated with proton pump (H+/K+-ATPase) inhibitors and/or a gastrin receptor (CCK2R) antagonist; H+/K+-ATPase β-subunit knockout (H/K-β KO) mice; and Mongolian gerbils infected with Helicobacter pylori and given a CCK2R antagonist. Biological function of secretory clusterin was studied in human gastric cancer cells. Clusterin was highly expressed in neuroendocrine cells in normal oxyntic mucosa of humans and rodents. In response to hypergastrinemia, expression of clusterin increased significantly and its localization shifted to basal groups of proliferative cells in the mucous neck cell-chief cell lineage in all animal models. That shift was partially inhibited by antagonizing the CCK2R in rats and gerbils. The oxyntic mucosa of H/K-β KO mice contained areas with clusterin-positive mucous cells resembling SPEM. In gastric adenocarcinomas, clusterin mRNA expression was higher in diffuse tumors containing signet ring cells compared with diffuse tumors without signet ring cells, and clusterin seemed to be secreted by tumor cells. In gastric cancer cell lines, gastrin increased secretion of clusterin, and both gastrin and secretory clusterin promoted survival after starvation- and chemotherapy-induced stress. Overall, our results indicate that clusterin is overexpressed in hypergastrinemic rodent models of oxyntic preneoplasia and stimulates gastric cancer cell survival.

Mouse models for gastric cancer: Matching models to biological questions

Gastric cancer is the third leading cause of cancer-related mortality worldwide. This is in part due to the asymptomatic nature of the disease, which often results in late-stage diagnosis, at which point there are limited treatment options. Even when treated successfully, gastric cancer patients have a high risk of tumor recurrence and acquired drug resistance. It is vital to gain a better understanding of the molecular mechanisms underlying gastric cancer pathogenesis to facilitate the design of new-targeted therapies that may improve patient survival. A number of chemically and genetically engineered mouse models of gastric cancer have provided significant insight into the contribution of genetic and environmental factors to disease onset and progression. This review outlines the strengths and limitations of current mouse models of gastric cancer and their relevance to the pre-clinical development of new therapeutics.

Effect of green tea catechins on gastric mucosal dysplasia in insulin-gastrin mice

Green tea catechins (GTCs) have been implicated in various physiological effects, including anti-carcinogenic activities. In the present study, we evaluated the effects of GTCs specifically on the development of gastritis and pre-malignant lesions in insulin-gastrin mice. Nine-week-old male INS-GAS mice (n=38) were supplemented with GTCs for 4 and 28 weeks, and their body weights, serum gastrin levels, histopathology and pro-inflammatory cytokine levels in gastric tissue and mucosal cell proliferation were monitored. Body weights of the GTC-treated mice were significantly lower than those of the untreated controls (P≤0.05). Serum gastrin levels were suppressed at the age of 37-weeks (P≤0.05). The histopathological scores indicated that the extent of dysplasia was significantly diminished (P≤0.05), although GTC supplementation did not affect the inflammation scores. The messenger RNA levels of interferon (IFN)-γ were significantly reduced at the age of 13 weeks (P≤0.05), although the changes did not reach statistical significance at the age of 37 weeks (P=0.056). The labeling index of Ki-67 immunohistochemistry was significantly decreased (P≤0.05). These results demonstrated that GTCs may play a protective role in the development of gastritis and pre-malignant lesions via an IFN-γ, gastrin, and mucosal cell proliferation-dependent mechanism in this rodent model and potentially in humans.

Effect of netazepide, a gastrin/CCK2 receptor antagonist, on gastric acid secretion and rabeprazole-induced hypergastrinaemia in healthy subjects

AIMS

To compare gastric acid suppression by netazepide, a gastrin/CCK2 receptor antagonist, with that by a proton pump inhibitor (PPI), and to determine if netazepide can prevent the trophic effects of PPI-induced hypergastrinaemia.

METHODS

Thirty healthy subjects completed a double-blind, randomized, parallel group trial of oral netazepide and rabeprazole, alone and combined, once daily for 6 weeks. Primary end points were: basal and pentagastrin-stimulated gastric acid and 24 h circulating gastrin and chromogranin A (CgA) at baseline, start and end of treatment, gastric biopsies at baseline and end of treatment and basal and pentagastrin-stimulated gastric acid and dyspepsia questionnaire after treatment withdrawal.

RESULTS

All treatments similarly inhibited pentagastrin-stimulated gastric acid secretion. All treatments increased serum gastrin, but the combination and rabeprazole did so more than netazepide alone. The combination also reduced basal acid secretion. Rabeprazole increased plasma CgA, whereas netazepide and the combination reduced it. None of the biopsies showed enterochromaffin-like (ECL) cell hyperplasia. Withdrawal of treatments led neither to rebound hyperacidity nor dyspepsia.

CONCLUSIONS

Netazepide suppressed pentagastrin-stimulated gastric acid secretion as effectively as did rabeprazole. The reduction in basal acid secretion and greater increase in serum gastrin by the combination is consistent with more effective acid suppression. Despite our failure to show rabeprazole-induced ECL cell hyperplasia and rebound hyperacidity, the increase in plasma CgA after rabeprazole is consistent with a trophic effect on ECL cells, which netazepide prevented. Thus, netazepide is a potential treatment for the trophic effects of hypergastrinaemia and, with or without a PPI, is a potential treatment for acid-related conditions.

Recapitulating Human Gastric Cancer Pathogenesis: Experimental Models of Gastric Cancer

This review focuses on the various experimental models to study gastric cancer pathogenesis, with the role of genetically engineered mouse models (GEMMs) used as the major examples. We review differences in human stomach anatomy compared to the stomachs of the experimental models, including the mouse and invertebrate models such as Drosophila and C. elegans. The contribution of major signaling pathways, e.g., Notch, Hedgehog, AKT/PI3K is discussed in the context of their potential contribution to foregut tumorigenesis. We critically examine the rationale behind specific GEMMs, chemical carcinogens, dietary promoters, Helicobacter infection, and direct mutagenesis of relevant oncogenes and tumor suppressor that have been developed to study gastric cancer pathogenesis. Despite species differences, more efficient and effective models to test specific genes and pathways disrupted in human gastric carcinogenesis have yet to emerge. As we better understand these species differences, "humanized" versions of mouse models will more closely approximate human gastric cancer pathogenesis. Towards that end, epigenetic marks on chromatin, the gut microbiota, and ways of manipulating the immune system will likely move center stage, permitting greater overlap between rodent and human cancer phenotypes thus providing a unified progression model.

Gastrin May Mediate the Carcinogenic Effect of Helicobacter pylori Infection of the Stomach

Gastric cancer occurs almost exclusively in patients with gastritis. Since Helicobacter pylori (Hp) was proved to cause gastritis, Hp was also expected to play a role in gastric carcinogenesis. Despite extensive studies, the mechanisms by which Hp cause gastric cancer are still poorly understood. However, there is evidence that the anatomical site of Hp infection is of major importance. Infection confined to the antral mucosa protects against gastric cancer but predisposes to duodenal ulcer, whereas Hp infection of the oxyntic mucosa increases the risk of gastric cancer. Hp infection does not predispose to cancers in the gastric cardia. In patients with atrophic gastritis of the oxyntic mucosa, the intragastric pH is elevated and the concentration of microorganisms in the stomach is increased. This does not lead to increased risk of gastric cancer at all anatomical sites. The site specificity of Hp infection in relation to cancer risk indicates that neither Hp nor the changes in gastric microflora due to gastric hypoacidity are carcinogenic per se. However, reduced gastric acidity also leads to hypergastrinemia, which stimulates the function and proliferation of enterochromaffin-like (ECL) cells located in the oxyntic mucosa. The ECL cell may be more important in human gastric carcinogenesis than previously realized, as every condition causing long-term hypergastrinemia in animals results in the development of neoplasia in the oxyntic mucosa. Patients with hypergastrinemia will far more often develop carcinomas in the gastric corpus. In conclusion, hypergastrinemia may explain the carcinogenic effect of Hp.

Effectiveness of individual-focused interventions to prevent chronic disease

BACKGROUND

The burden of chronic disease is projected to assume crisis proportions in most parts of the world by the middle of the century, focusing attention on the need for preventive interventions. We identify and review published research on primary prevention individual-level interventions in current practice and describe and discuss the limitations of the current evidence. The report facilitates prioritizing a research agenda for potential interventions that might be investigated within cohort studies.

MATERIALS AND METHODS

This study is a rapid review. Computerized database searches (PubMed and EMBASE) were performed in October 2012 to identify articles on primary prevention interventions that are directed at the individual level. Potentially, relevant International Agency of Research on Cancer handbooks and monographs were also reviewed. The review includes articles reported in English on the efficacy or effectiveness of a preventive intervention in an adult population. It excludes articles on alcohol or tobacco smoking.

RESULTS

Many chronic disease interventions directed at individuals report a protective effect in the short term and some evidence for the efficacy of chemoprevention in chronic disease prevention exists. Evidence these effects persist in the longer term is inconsistent.

CONCLUSIONS

There are currently only limited evidence-based preventions for most chronic diseases, for which a summary is available in Table A1 (see Appendix B). Most individual-level intervention research studies have been conducted using case-control designs and some small, randomized studies. There are fewer impediments to lifestyle modifications when compared to prevention using chemoprevention and vaccination or other methods of prevention of persistent infection.

Netazepide, a gastrin/CCK2 receptor antagonist, causes dose-dependent, persistent inhibition of the responses to pentagastrin in healthy subjects

AIMS

To confirm by means of pentagastrin, a synthetic gastrin agonist, that netazepide is a gastrin/CCK2 receptor antagonist in healthy subjects, and that antagonism persists during repeated dosing.

METHODS

We did two studies in which we infused pentagastrin (0.6 μg kg(-1)  h(-1) intravenously), aspirated gastric secretion and measured the volume, pH and H(+) secretion rate of the gastric aspirate. First, we did a double-blind, five-way crossover study (n = 10) to assess the effect of single oral doses of netazepide (1, 5, 25 and 100 mg) and placebo on the response to pentagastrin. Then, we did a single-blind, placebo-controlled study (n = 8) to assess the effect of the first and last oral doses of netazepide (100 mg) twice daily for 13 doses on the response to pentagastrin.

RESULTS

Netazepide was well tolerated. After placebo, pentagastrin increased the volume and H(+) secretion rate and reduced the pH of gastric aspirate. Compared with placebo, single doses of netazepide caused dose-dependent inhibition of the pentagastrin response (P < 0.02); netazepide (100 mg) abolished the response. After 13 doses, the reduction in volume and H(+) secretion rate persisted (P < 0.001), but the pH effect was mostly lost.

CONCLUSIONS

Netazepide is an orally active, potent, competitive antagonist of human gastrin/CCK2 receptors. Antagonism is dose dependent and persists during repeated dosing, despite tolerance to the effect on pH. Further studies are required to explain that tolerance. Netazepide is a tool to study the physiology and pharmacology of gastrin, and merits studies in patients to assess its potential to treat gastric acid-related conditions and the trophic effects of hypergastrinaemia.

Effect of repeated doses of netazepide, a gastrin receptor antagonist, omeprazole and placebo on 24 h gastric acidity and gastrin in healthy subjects

AIM

To administer repeated oral doses of netazepide to healthy subjects for the first time, to assess safety, tolerability, pharmacokinetics and effect on 24 h gastric pH and plasma gastrin.

METHOD

We did two randomized, double-blind, parallel group studies. The first compared netazepide 25 and 100 mg 12 hourly, omeprazole 20 mg once daily and placebo for 7 days. On day 7 only, we measured pH and assayed plasma gastrin. The second study compared netazepide 5, 10 and 25 mg and placebo once daily for 14 days. We measured pH on days 1, 7 and 14 and assayed plasma gastrin on days 1 and 14. We compared treatments by time gastric pH ≥ 4 during 0-4, 4-9, 9-13 and 13-24 h after the morning dose, and by plasma gastrin. P < 0.05 was significant.

RESULTS

Netazepide was well tolerated. On day 7 of the first study, netazepide increased pH significantly only during 9-13 h after the 100 mg dose, whereas omeprazole raised pH significantly during all periods. Both netazepide and omeprazole increased plasma gastrin significantly. Netazepide had linear pharmacokinetics. In the second study, netazepide caused dose-dependent, sustained increases in pH on day 1, but as in the first study, netazepide had little effect on pH on days 7 and 14. Again, netazepide increased plasma gastrin significantly.

CONCLUSION

Although repeated doses of netazepide led to tolerance to its effect on pH, the accompanying increase in plasma gastrin is consistent with continued inhibition of acid secretion, via gastrin receptor antagonism and gene up-regulation.

Mouse models of gastric carcinogenesis

Gastric cancer is one of the most common cancers in the world. Animal models have been used to elucidate the details of the molecular mechanisms of various cancers. However, most inbred strains of mice have resistance to gastric carcinogenesis. Helicobacter infection and carcinogen treatment have been used to establish mouse models that exhibit phenotypes similar to those of human gastric cancer. A large number of transgenic and knockout mouse models of gastric cancer have been developed using genetic engineering. A combination of carcinogens and gene manipulation has been applied to facilitate development of advanced gastric cancer; however, it is rare for mouse models of gastric cancer to show aggressive, metastatic phenotypes required for preclinical studies. Here, we review current mouse models of gastric carcinogenesis and provide our perspectives on future developments in this field.

Dietary factors modulate Helicobacter-associated gastric cancer in rodent models

Since its discovery in 1982, the global importance of Helicobacter pylori-induced disease, particularly in developing countries, remains high. The use of rodent models, particularly mice, and the unanticipated usefulness of the gerbil to study H. pylori pathogenesis have been used extensively to study the interactions of the host, the pathogen, and the environmental conditions influencing the outcome of persistent H. pylori infection. Dietary factors in humans are increasingly recognized as being important factors in modulating progression and severity of H. pylori-induced gastric cancer. Studies using rodent models to verify and help explain mechanisms whereby various dietary ingredients impact disease outcome should continue to be extremely productive.

The gastrin receptor antagonist netazepide (YF476) prevents oxyntic mucosal inflammation induced by Helicobacter pylori infection in Mongolian gerbils

OBJECTIVE

Long-term Helicobacter pylori infection causes gastritis leading to hypergastrinemia and predisposes to gastric cancer. Our aim was to assess the role of gastrin in oxyntic mucosal inflammation in H. pylori-infected Mongolian gerbils by means of the gastrin receptor antagonist netazepide (YF476).

DESIGN

We studied 60 gerbils for 18 months and left five animals uninfected (control group), inoculated 55 with H. pylori, and treated 28 of the infected animals with netazepide (Hp+YF476 group). Twenty-seven infected animals were given no treatment (Hp group). We measured plasma gastrin and intraluminal pH. H. pylori detection and histologic evaluations of the stomach were carried out.

RESULTS

All 55 inoculated animals were H. pylori positive at termination. Eighteen animals in the Hp group had gastritis. There was a threefold increase in mucosal thickness in the Hp group compared to the Hp+YF476 group, and a threefold increase in oxyntic neuroendocrine cells in the Hp group compared to the Hp+YF476 group (p < .05). All animals in the Hp+YF476 group had macro- and microscopically normal findings in the stomach. Plasma gastrin was higher in the Hp group than in the control group (172 ± 16 pmol/L vs 124 ± 5 pmol/L, p < .05) and highest in the Hp+YF476 group (530 ± 36 pmol/L). Intraluminal pH was higher in the Hp group than in the Hp+YF476 group (2.51 vs 2.30, p < .05).

CONCLUSION

The gastrin antagonist netazepide prevents H. pylori-induced gastritis in Mongolian gerbils. Thus, gastrin has a key role in the inflammatory reaction of the gastric mucosa to H. pylori infection in this species.

The role of the gastrointestinal microbiome in Helicobacter pylori pathogenesis

The discovery of Helicobacter pylori overturned the conventional dogma that the stomach was a sterile organ and that pH values<4 were capable of sterilizing the stomach. H. pylori are an etiological agent associated with gastritis, hypochlorhydria, duodenal ulcers, and gastric cancer. It is now appreciated that the human stomach supports a bacterial community with possibly 100s of bacterial species that influence stomach homeostasis. Other bacteria colonizing the stomach may also influence H. pylori-associated gastric pathogenesis by creating reactive oxygen and nitrogen species and modulating inflammatory responses. In this review, we summarize the available literature concerning the gastric microbiota in humans, mice, and Mongolian gerbils. We also discuss the gastric perturbations, many involving H. pylori, that facilitate the colonization by bacteria from other compartments of the gastrointestinal tract, and identify risk factors known to affect gastric homeostasis that contribute to changes in the microbiota.

Netazepide, a gastrin receptor antagonist, normalises tumour biomarkers and causes regression of type 1 gastric neuroendocrine tumours in a nonrandomised trial of patients with chronic atrophic gastritis

INTRODUCTION

Autoimmune chronic atrophic gastritis (CAG) causes hypochlorhydria and hypergastrinaemia, which can lead to enterochromaffin-like (ECL) cell hyperplasia and gastric neuroendocrine tumours (type 1 gastric NETs). Most behave indolently, but some larger tumours metastasise. Antrectomy, which removes the source of the hypergastrinaemia, usually causes tumour regression. Non-clinical and healthy-subject studies have shown that netazepide (YF476) is a potent, highly selective and orally-active gastrin/CCK-2 receptor antagonist. Also, it is effective in animal models of ECL-cell tumours induced by hypergastrinaemia.

AIM

To assess the effect of netazepide on tumour biomarkers, number and size in patients with type I gastric NETs.

METHODS

We studied 8 patients with multiple tumours and raised circulating gastrin and chromogranin A (CgA) concentrations in an open trial of oral netazepide for 12 weeks, with follow-up 12 weeks later. At 0, 6, 12 and 24 weeks, we carried out gastroscopy, counted and measured tumours, and took biopsies to assess abundances of several ECL-cell constituents. At 0, 3, 6, 9, 12 and 24 weeks, we measured circulating gastrin and CgA and assessed safety and tolerability.

RESULTS

Netazepide was safe and well tolerated. Abundances of CgA (p<0.05), histidine decarboxylase (p<0.05) and matrix metalloproteinase-7(p<0.10) were reduced at 6 and 12 weeks, but were raised again at follow-up. Likewise, plasma CgA was reduced at 3 weeks (p<0.01), remained so until 12 weeks, but was raised again at follow-up. Tumours were fewer and the size of the largest one was smaller (p<0.05) at 12 weeks, and remained so at follow-up. Serum gastrin was unaffected.

CONCLUSION

The reduction in abundances, plasma CgA, and tumour number and size by netazepide show that type 1 NETs are gastrin-dependent tumours. Failure of netazepide to increase serum gastrin further is consistent with achlorhydria. Netazepide is a potential new treatment for type 1 NETs. Longer, controlled trials are justified.

TRIAL REGISTRATION

European Union EudraCT database 2007-002916-24 https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-002916-24ClinicalTrials.gov NCT01339169 http://clinicaltrials.gov/ct2/show/NCT01339169?term=yf476&rank=5.

MiR-148a regulates the growth and apoptosis in pancreatic cancer by targeting CCKBR and Bcl-2

Our previous studies have revealed that miR-148a is downregulated in pancreatic cancer. Bioinformatics analysis has shown cholecystokinin-B receptor (CCKBR) and B cell lymphoma (Bcl-2) to be potential targets of miR-148a. But the pathophysiologic role of miR-148a and its relevance to the growth and development of pancreatic cancer are yet to be investigated. The purpose of this study is to elucidate the molecular mechanisms where miR-148a acts as a tumor suppressor in pancreatic cancer. Our results showed significant downregulation of miR-148a in 28 pancreatic cancer tissue samples and five pancreatic cancer cell lines, compared with their non-tumor counterparts by qRT-PCR. MiR-148a was found to not only inhibit the proliferation of pancreatic cancer cells (PANC-1 and AsPC-1) in vitro by MTT assay and colony formation assay, but also to promote cells apoptosis in vitro by Annexin V-FITC apoptosis detection and caspase activity assay. Using western blot and luciferase activity assay, CCKBR and Bcl-2 were identified as targets of miR-148a. Moreover, we also found that the expression of Bcl-2 lacking in 3'UTR could abrogate the pro-apoptosis function of miR-148a. These findings suggest the importance of miR-148a's targeting of CCKBR and Bcl-2 in the regulation of pancreatic cancer growth and apoptosis.

High expression of gastrin receptor protein in injured mucosa of Helicobacter pylori-positive gastritis

BACKGROUND AND AIM

Gastrin is a growth factor for the gastric epithelial cells. However, it is unknown how gastric receptor (GR) expression is regulated in the gastric mucosa. We studied GR expression using a newly raised antibody and investigated the relationship between GR expression and gastritis.

METHODS

Gastric receptor expression in 63 human gastric mucosa was studied. Helicobacter pylori infection and histological gastritis status were evaluated in gastric biopsy samples. In gastric ulcer cases, additional biopsy specimens were taken from injured mucosa. Fasting sera were collected and serum gastrin level evaluated. MKN-28 cells were cultured at various pH conditions, and the change in GR expression was determined.

RESULTS

Gastric receptor expression was detected in the foveolar epithelium of the gastric mucosa, and its expression was stronger in patients infected with H. pylori. In particular, higher expression was detected in regenerating injured mucosa. There was no association between gastritis score/serum gastrin level and GR expression in H. pylori-positive cases. In MKN-28 cells, GR protein expression was lower in neutral conditions than in acidic or alkaline conditions.

CONCLUSION

Gastric mucosal injury with H. pylori infection destroys the pH barrier on the foveolar epithelium and may induce GR expression through pH changes.

Mouse models of gastric cancer

Animal models have greatly enriched our understanding of the molecular mechanisms of numerous types of cancers. Gastric cancer is one of the most common cancers worldwide, with a poor prognosis and high incidence of drug-resistance. However, most inbred strains of mice have proven resistant to gastric carcinogenesis. To establish useful models which mimic human gastric cancer phenotypes, investigators have utilized animals infected with Helicobacter species and treated with carcinogens. In addition, by exploiting genetic engineering, a variety of transgenic and knockout mouse models of gastric cancer have emerged, such as INS-GAS mice and TFF1 knockout mice. Investigators have used the combination of carcinogens and gene alteration to accelerate gastric cancer development, but rarely do mouse models show an aggressive and metastatic gastric cancer phenotype that could be relevant to preclinical studies, which may require more specific targeting of gastric progenitor cells. Here, we review current gastric carcinogenesis mouse models and provide our future perspectives on this field.

Gastric and duodenal neuroendocrine tumours

Gastric neuroendocrine neoplasms (NENs) are increasing in frequency and have a varied spectrum with regard to histology, clinicopathologic background, stage, and prognosis. They are usually discovered incidentally, are for the most part benign and are associated with hypergastrinaemia (secondary either to chronic atrophic gastritis or rarely Zollinger-Ellison syndrome; types 1 and 2, respectively) or more rarely sporadic type 3. Applications of recent staging and grading systems - namely using Ki-67 proliferative indices - (from ENETS and WHO 2010) can be particularly helpful in further categorising these tumours. The natural history of Type 1 gastric carcinoids is generally (>95%) favourable and simple surveillance is usually recommended for small (<1 cm) T1 tumours, with local (endoscopic or surgical) resection for larger lesions. Other potential therapies such as somatostatin analogues and gastrin receptor antagonists may offer newer therapeutic possibilities. Rarely, gastric NENs have a malignant course and this is usually confined to Type 2 and especially Type 3 tumours; the latter mimic the biological course of gastric adenocarcinoma and require radical oncological therapies. Most duodenal NENs, apart from gastrinomas (that are not dealt with here) are sporadic and non functional. They are also increasing in frequency probably due to incidental discovery at endoscopy or imaging for other reasons and this may account for their overall good prognosis. Peri-ampullary and ampullary NENs may have a more aggressive outcome and should be carefully appraised and treated (often with surgical resection).

Treatment of gastric carcinoids type 1 with the gastrin receptor antagonist netazepide (YF476) results in regression of tumours and normalisation of serum chromogranin A

BACKGROUND

Patients with chronic atrophic gastritis have long-term gastric hypoacidity, and secondary hypergastrinaemia. Some also develop gastric ECL cells carcinoids (type 1 GC). Most type 1 GC remain indolent, but some metastasise. Patients undergo surveillance, and some are treated with somatostatin analogues, endoscopic resection or surgery. Netazepide (YF476) is a highly selective, potent and orally active gastrin receptor antagonist, which has anti-tumour activity in various rodent models of gastric neoplasia driven by hypergastrinaemia. Netazepide has been studied in healthy volunteers.

AIM

To assess the effect of netazepide on type 1 GC.

METHODS

Eight patients with multiple type 1 GC received oral netazepide once daily for 12 weeks, with follow-up at 12 weeks in an open-label, pilot trial. Upper endoscopy was performed at 0, 6, 12 and 24 weeks, and carcinoids were counted and measured. Fasting serum gastrin and chromogranin A (CgA) and safety and tolerability were assessed at 0, 3, 6, 9, 12 and 24 weeks.

RESULTS

Netazepide was well tolerated. All patients had a reduction in the number and size of their largest carcinoid. CgA was reduced to normal levels at 3 weeks and remained so until 12 weeks, but had returned to pre-treatment levels at 24 weeks. Gastrin remained unchanged throughout treatment.

CONCLUSIONS

The gastrin receptor antagonist netazepide is a promising new medical treatment for type 1 gastric carcinoids, which appear to be gastrin-dependent. Controlled studies and long-term treatment are justified to find out whether netazepide treatment can eradicate type 1 gastric carcinoids.

Barrett esophagus: what a mouse model can teach us about human disease

The incidence of esophageal adenocarcinoma (EAC) is rapidly rising in the western world and accounts for 2% of all cancer-related deaths. The precursor lesion for EAC is Barrett esophagus (BE), which is strongly associated with gastresophageal reflux disease. A major limitation to the study of EAC has been the absence of tractable and genetically modifiable preclinical models of BE. A mouse model of BE and EAC that resembles human disease could provide novel insights into the origins and molecular pathogenesis of BE. In addition, validated animal models could help stratify BE patients given the limited predictive power of current standard endoscopic measures and clinical assessment. Here, we review the findings from recently developed mouse models of BE and EAC and their impact on clinical decision making, surveillance programs and therapeutic options. The data, taken together, suggest potential origins of BE from the gastric cardia, a role of bile acid and hypergatrinemia for carcinogenesis, a growing importance for columnar-like epithelium and a critical role for Notch signaling.

Targeting STAT3 in gastric cancer

INTRODUCTION

STAT3 is a key transcription factor for many regulatory factors that modulate gene transcription. Particularly important are cytokines and growth factors that maintain homeostasis by regulating immunocytes, stromal and epithelial cells. Dysregulation of STAT3 by constitutive activation plays an important role in the initiation of inflammation and cellular transformation in numerous cancers, especially of epithelial origin. This review focuses on STAT3 drive in gastric cancer initiation and progression, with emphasis on its activation by cytokines, and how targeting the primary drivers or gastric STAT3 therapeutically may prevent or slow stomach cancer development.

AREAS COVERED

This review will discuss the mechanics of STAT3 signalling, how constitutive STAT3 activation promotes gastric tumourigenesis in both human adenocarcinomas and mouse models, the nature of the upstream regulators of STAT3, and their association with chronic Helicobacter pylori infection, STAT3-activated genes that promote transformation and progression, and finally the development and use of STAT3 and upstream cytokine inhibitors as therapeutics.

EXPERT OPINION

Chronic STAT3 activation is a key event in gastric cancer induction and progression. Specific targeting of stomach epithelial STAT3 or blocking IL-11Rα/gp130 and/or EGFR signal transduction in chronic gastric inflammation and metaplasia may be therapeutically effective in preventing gastric carcinogenesis.

Association between common genetic variant of HRH2 and gastric cancer risk

Histamine plays important physiological roles in the upper gastrointestinal tract and acts via the H2 receptor. The -1018 G>A (rs2067474) in an enhancer element of the promoter and non-synonymous rs79385261 (Asn46Thr) were identified in HRH2. We attempted to clarify the associations of these polymorphisms with gastric carcinogenesis. The study was performed in 321 patients with gastric cancer and 599 subjects with no evidence of gastric malignancies on upper gastroduodenal endoscopy. The genotypes were determined using a one-tube multiplex PCR-SSCP method. The degree of gastritis was assessed in 496 subjects and serum pepsinogen (PG) I/II levels were measured in 124 subjects without gastric cancer. The minor allele of Asn46Thr could not be detected. The frequencies of the -1018 A allele in the non-GC and GC groups were 13.5% and 8.26%, respectively (p=0.00077). Overall, -1018 GG homozygotes had an increased risk for developing gastric cancer (OR 1.68; 95% CI 1.17-2.42; p=0.0052), especially intestinal type cancer (OR 1.94; 95% CI 1.23-3.08; p=0.0047). In subjects aged >60 years, the adjusted risk for gastric cancer among individuals who were -1018 GG homozygotes was 1.87 (range 1.19-2.93; p=0.0065) compared with A carriers. In the gastric cancer cases located in the antrum and at comparative advanced stage, -1018 GG homozygosity was a significantly increased risk factor. In subjects >60 years, the metaplasia score was significantly higher in -1018 GG homozygotes than A carriers. Both atrophy and metaplasia scores were significantly increased with age only in -1018 GG homozygotes. The PG I/II ratio was significantly decreased in H. pylori positive GG homozygotes than negative GG homozygotes and positive A carriers. Our results suggest that -1018 GG homozygosity of HRH2 may be associated with the severity of gastric mucosal atrophy. This genotype has an increased risk for the subsequent development of gastric cancer, especially intestinal type, at advanced age.

Deletion and down-regulation of HRH4 gene in gastric carcinomas: a potential correlation with tumor progression

BACKGROUND

Histamine is an established growth factor for gastrointestinal malignancies. The effect of histamine is largely determined locally by the histamine receptor expression pattern. Histamine receptor H4 (HRH4), the newest member of the histamine receptor family, is positively expressed on the epithelium of the gastrointestinal tract, and its function remains to be elucidated. Previously, we reported the decreased expression of HRH4 in colorectal cancers and revealed its correlation with tumor proliferation. In the current study, we aimed to investigate the abnormalities of HRH4 gene in gastric carcinomas (GCs).

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed H4R expression in collected GC samples by quantitative PCR, Western blot analysis, and immunostaining. Our results showed that the protein and mRNA levels of HRH4 were reduced in some GC samples, especially in advanced GC samples. Copy number decrease of HRH4 gene was observed (17.6%, 23 out of 131), which was closely correlated with the attenuated expression of H4R. In vitro studies, using gastric cancer cell lines, showed that the alteration of HRH4 expression on gastric cancer cells influences tumor growth upon exposure to histamine.

CONCLUSIONS/SIGNIFICANCE

We show for the first time that deletion of HRH4 gene is present in GC cases and is closely correlated with attenuated gene expression. Down-regulation of HRH4 in gastric carcinomas plays a role in histamine-mediated growth control of GC cells.

In vivo analysis of mouse gastrin gene regulation in enhanced GFP-BAC transgenic mice

Gastrin is secreted from a subset of neuroendocrine cells residing in the gastric antrum known as G cells, but low levels are also expressed in fetal pancreas and intestine and in many solid malignancies. Although past studies have suggested that antral gastrin is transcriptionally regulated by inflammation, gastric pH, somatostatin, and neoplastic transformation, the transcriptional regulation of gastrin has not previously been demonstrated in vivo. Here, we describe the creation of an enhanced green fluorescent protein reporter (mGAS-EGFP) mouse using a bacterial artificial chromosome that contains the entire mouse gastrin gene. Three founder lines expressed GFP signals in the gastric antrum and the transitional zone to the corpus. In addition, GFP(+) cells could be detected in the fetal pancreatic islets and small intestinal villi, but not in these organs of the adult mice. The administration of acid-suppressive reagents such as proton pump inhibitor omeprazole and gastrin/CCK-2 receptor antagonist YF476 significantly increased GFP signal intensity and GFP(+) cell numbers in the antrum, whereas these parameters were decreased by overnight fasting, octreotide (long-lasting somatostatin ortholog) infusion, and Helicobacter felis infection. GFP(+) cells were also detected in the anterior lobe of the pituitary gland and importantly in the colonic tumor cells induced by administration with azoxymethane and dextran sulfate sodium salt. This transgenic mouse provides a useful tool to study the regulation of mouse gastrin gene in vivo, thus contributing to our understanding of the mechanisms involved in transcriptional control of the gastrin gene.

Animal models to study the role of long-term hypergastrinemia in gastric carcinogenesis

Patients with chronic hypergastrinemia due to chronic atrophic gastritis or gastrinomas have an increased risk of developing gastric malignancy, and it has been questioned whether also patients with hypergastrinemia caused by long-term use of acid inhibiting drugs are at risk. Gastric carcinogenesis in humans is affected by numerous factors and progresses slowly over years. When using animal models with the possibility of intervention, a complex process can be dissected by studying the role of hypergastrinemia in carcinogenesis within a relatively short period of time. We have reviewed findings from relevant models where gastric changes in animal models of long-term hypergastrinemia have been investigated. In all species where long-term hypergastrinemia has been induced, there is an increased risk of gastric malignancy. There is evidence that hypergastrinemia is a common causative factor in carcinogenesis in the oxyntic mucosa, while other cofactors may vary in the different models.

Histamine regulation of hyperplastic and neoplastic cell growth in cholangiocytes

Histamine has long been known to be involved in inflammatory events. The discovery of antihistamines dates back to the first half of the 20^th century when a Swiss-Italian pharmacologist, Daniel Bovet began his work. In 1957 he was awarded a Nobel Prize for his production of antihistamines for allergy relief. Since that time, histamine has been found to play a role in other events besides allergic reaction. Possibly unbelievable to Bovet and his peers, histamine has now been marked as playing a role in liver pathologies including hepatobiliary diseases.

Conditional deletion of IkappaB-kinase-beta accelerates helicobacter-dependent gastric apoptosis, proliferation, and preneoplasia

BACKGROUND & AIMS

The nuclear factor kappaB (NF-kappaB)/IkappaB-kinase-beta (IKKbeta) pathway has been shown to represent a key link between inflammation and cancer, inducing pro-inflammatory cytokines in myeloid cells and anti-apoptotic pathways in epithelial cells. However, the role of NF-kappaB pathway in gastric carcinogenesis and injury has not been well-defined. We derived mice with a conditional knockout of IKKbeta in gastric epithelial cells (GECs) and myeloid cells, and examined responses to ionizing radiation (IR) and Helicobacter felis infection.

METHODS

Ikkbeta(Deltastom) mice were generated by crossing Foxa3-Cre mice to Ikkbeta(F/F) mice. Cellular stress was induced with IR and H felis in Ikkbeta(Deltastom), Ikkbeta(F/F), and cis-NF-kappaB-enhanced green fluorescent protein (GFP) reporter mice. Gastric histopathology, apoptosis, proliferation, necrosis, reactive oxygen species, and expression of cytokines, chemokines, and anti-apoptotic genes were assessed. The role of myeloid IKKbeta in these models was studied by crosses with LysM-Cre mice.

RESULTS

NF-kappaB activity was upregulated in myeloid cells with acute H felis infection, but in GECs by IR or long-term H felis infection during progression to dysplasia. Deletion of IKKbeta in GECs led to increased apoptosis, reactive oxygen species, and cellular necrosis, and resulted in up-regulation of interleukin-1alpha and down-regulation of anti-apoptotic genes. Loss of IKKbeta in GECs resulted in worse inflammation and more rapid progression to gastric preneoplasia, while loss of IKKbeta in myeloid cells inhibited development of gastric atrophy.

CONCLUSIONS

The loss of IKKbeta/NF-kappaB signaling in GECs results in increased apoptosis and necrosis in response to cellular stress, and accelerated development of dysplasia by Helicobacter infection.

Combination of sulindac and antimicrobial eradication of Helicobacter pylori prevents progression of gastric cancer in hypergastrinemic INS-GAS mice

Helicobacter pylori infection causes severe dysplasia manifested as gastrointestinal intraepithelial neoplasia (GIN) after 28 weeks post-H. pylori infection (WPI) in cancer-prone, hypergastrinemic male INS-GAS mice. We examined the efficacy of the nonsteroidal anti-inflammatory drug sulindac (400 ppm in drinking water) alone, the CCK2/gastrin receptor antagonist YM022 (45 mg/kg/wk) alone, and sulindac or YM022 combined with H. pylori eradication therapy to prevent H. pylori-associated gastric cancer in male INS-GAS mice. Treatments started at 22 WPI, and mice were euthanized at 28 WPI. In uninfected mice, all treatments significantly delayed development of spontaneous GIN (P < 0.05). In H. pylori-infected mice, sulindac alone or YM022 alone had no protective effect on H. pylori-associated GIN. Importantly, sulindac exacerbated the severity of H. pylori-associated gastritis despite decreased gastric prostaglandin E(2) levels. However, sulindac combined with H. pylori antimicrobial eradication reduced the incidence of GIN (P < 0.05), whereas YM022 combined with antimicrobial eradication did not reduce GIN. In infected mice, sulindac or YM022 treatment did not alter gastric expression of the proinflammatory cytokines Ifn-gamma and Tnf-alpha and mucosal cell proliferation. Sulindac or YM022 combined with antimicrobial eradication down-regulated mRNA levels of Ifn-gamma and Tnf-alpha and mucosal cell proliferation (P < 0.05). We conclude that sulindac enhances H. pylori gastritis and may promote inflammation-mediated gastric carcinogenesis. The combination of sulindac and antimicrobial H. pylori eradication was beneficial for reducing proinflammatory cytokine mRNA in the stomach and preventing progression from severe dysplasia to gastric cancer in H. pylori-infected INS-GAS mice.

Gastrin induces the interaction between human mononuclear leukocytes and endothelial cells through the endothelial expression of P-selectin and VCAM-1

Gastric mucosal inflammation is frequently associated with hypergastrinemia, and a correlation exists between the level of gastrin and degree of gastritis. We have previously observed that gastrin promotes leukocyte-endothelial interactions and contributes to Helicobacter-induced inflammation in the rat mesentery. In the present study, we aimed to evaluate a possible proinflammatory activity of gastrin in humans. The interaction between human leukocytes [U-937 cells, peripheral blood polymorphonuclear (PMN), and peripheral blood mononuclear (PBMC) cells] and human umbilical vein endothelial cells (HUVEC) was analyzed in static and dynamic conditions. The endothelial expression of adhesion molecules [P-selectin, E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule (VCAM)-1] was analyzed by flow cytometry and fluorescent microscopy screening. Gastrin increased the static adhesion of U-937 cells to HUVEC (1 h; 10(-9) M: 122 +/- 9%; 10(-8) M: 143 +/- 17%; 10(-7) M: 162 +/- 14% vs. control, all P < 0.05). Incubation of HUVEC with gastrin (4 h) also increased PBMC rolling (vehicle: 63 +/- 12; 10(-9) M: 109 +/- 29; 10(-8) M: 141 +/- 24; 10(-7) M: 261 +/- 16 leukocytes/min, P < 0.05) and adhesion (vehicle: 3 +/- 2, 10(-9) M: 11 +/- 4, 10(-8) M: 17 +/- 5, 10(-7) M: 15 +/- 5 leukocytes/mm(2), all P < 0.05) in the parallel-plate flow chamber. Treatment of PBMC with gastrin had no effects. The cholecystokinin (CCK)-2 receptor antagonist (L-365,260, 10(-7) M) prevented the effects of gastrin. P-selectin and VCAM-1 expression were enhanced by gastrin, and neutralizing antibodies against these molecules prevented PBMC rolling and adhesion. Gastrin did not affect the interactions between HUVEC and PMN. Gastrin induces interactions between human mononuclear leukocytes and endothelial cells through the activation of CCK-2 receptors and the enhancement of endothelial P-selectin and VCAM-1.

Inactivating cholecystokinin-2 receptor inhibits progastrin-dependent colonic crypt fission, proliferation, and colorectal cancer in mice

Hyperproliferation of the colonic epithelium, leading to expansion of colonic crypt progenitors, is a recognized risk factor for colorectal cancer. Overexpression of progastrin, a nonamidated and incompletely processed product of the gastrin gene, has been shown to induce colonic hyperproliferation and promote colorectal cancer in mice, but the mechanism of pathogenesis has not been defined. Cholecystokinin-2 receptor (CCK2R) is the primary receptor for cholecystokinin (CCK) and amidated gastrin. Here, we show that Cck2r was expressed in murine colonic crypts and upregulated in the transgenic mice that overexpress human progastrin. Murine deletion of Cck2r abrogated progastrin-dependent increases in colonic proliferation, mucosal thickness, and beta-catenin and CD44 expression in the colon tumor. In addition, either deletion or antagonism of Cck2r resulted in the inhibition of progastrin-dependent increases in progenitors expressing doublecortin and CaM kinase-like-1 (DCAMKL1), stem cells expressing leucine rich repeat-containing G protein-coupled receptor 5 (LgR5), and colonic crypt fission. Furthermore, in the azoxymethane mouse model of colorectal carcinogenesis, Cck2r deletion in human progastrin-overexpressing mice resulted in markedly decreased aberrant crypt foci formation and substantially reduced tumor size and multiplicity. Taken together, these observations indicate that progastrin induces proliferative effects, primarily in colonic progenitor cells, through a CCK2R-dependent pathway. Moreover, our data suggest that CCK2R may be a potential target in the treatment or prevention of colorectal cancer.

Gastrin is an essential cofactor for helicobacter-associated gastric corpus carcinogenesis in C57BL/6 mice

We have previously described a synergistic interaction between hypergastrinemia and Helicobacter felis infection on gastric corpus carcinogenesis in FVB/N mice housed under specific-pathogen-free conditions. However, gastrin-deficient (GAS-KO) mice on a mixed C57BL/6/129Sv genetic background maintained in conventional housing were reported to develop spontaneous gastric antral tumors. Therefore, we investigated the role of gastrin in Helicobacter-associated gastric carcinogenesis in H. felis-infected mice on a uniform C57BL/6 background housed in specific-pathogen-free conditions. Hypergastrinemic transgenic (INS-GAS) mice, GAS-KO mice, and C57BL/6 wild-type mice were infected with H. felis for either 12 or 18 months. At 12 months postinfection, INS-GAS mice had mild corpus dysplasia, while B6 wild-type mice had either severe gastritis or metaplasia, and GAS-KO mice had only mild to moderate gastritis. At 18 months postinfection, both INS-GAS and B6 wild-type mice had both severe atrophic gastritis and corpus dysplasia, while GAS-KO mice had severe gastritis with mild gastric atrophy, but no corpus dysplasia. In contrast, both GAS-KO and B6 wild-type mice had mild to moderate antral dysplasia, while INS-GAS mice did not. H. felis antral colonization remained stable over time among the three groups of mice. These results point to a distinct effect of gastrin on carcinogenesis of both the gastric corpus and antrum, suggesting that gastrin is an essential cofactor for gastric corpus carcinogenesis in C57BL/6 mice.

Molecular aspects in the diagnosis of gastric cancer

BACKGROUND

Gastric cancer (GC) represents the second most common cause of cancer-related death worldwide. The prognosis remains poor, with limited treatment options. A better understanding of the initiation and progression of GC would enable the development of general screening strategies and individualized treatment modalities.

OBJECTIVE

The assessment of tools and molecular markers for the early detection and diagnosis of GC.

METHODS

Human clinical studies published within the past 5 years are reviewed. Also, significant previous data on markers in clinical use or on relevant animal or cell culture experiments are considered.

RESULTS/CONCLUSION

Serum-based screening strategies are not ready for routine application but represent an opportunity for the identification of individuals at high risk with the need for primary gastroscopy and further surveillance, which would ultimately improve survival and prognosis of GC. Infection with Helicobacter pylori represents the principal risk factor for gastric carcinogenesis. Bacterial virulence and host genetic factors contribute to individual susceptibility. Key molecular alterations in gastric carcinogenesis are related to intra- and extracellular cascades that regulate cell proliferation, tumor invasion and metastastic spread. For the development of effective prevention and treatment modalities, it is essential to unravel the basic mechanisms of gastric carcinogenesis.

Inflammation and foveolar hyperplasia are reduced by supplemental dietary glutamine during Helicobacter pylori infection in mice

We recently showed that L-Gln protects cultured gastric cells from ammonia-induced cell death and predicted that Gln may also protect during Helicobacter pylori infection in vivo. Thus, the aim of this study was to test whether supplemental dietary Gln protects against H. pylori-associated pathology. For this, C57BL/6 mice were fed a purified diet consisting of 20.3% protein (1.9% Gln), 66% carbohydrate, and 5% fat or 25.3% protein (5% supplemental L-Gln; 6.9% total Gln), 61% carbohydrate, and 5% fat. After a 2-wk prefeeding period, mice were divided into sham-(uninfected) or H. pylori-infected groups. Body weight and food consumption were recorded weekly. Tissue histopathology, H. pylori colonization, serum IgG, and pro- and antiinflammatory cytokine mRNA expression were determined at 6, 12, and 20 wk postinfection (wkPI). Inflammation, antiinflammatory cytokine, and interleukin-1beta mRNA expression were significantly greater at 6 wkPI in H. pylori-infected mice fed supplemental Gln compared with those fed the control diet. At 20 wkPI, however, inflammation and foveolar hyperplasia were significantly lower in H. pylori-infected mice fed supplemental Gln compared with those fed the control diet. Body weight gain, food consumption, H. pylori colonization, and serum IgG did not differ in H. pylori-infected mice fed supplemental Gln compared with the control diet. Our data demonstrate that H. pylori-infected mice fed supplemental dietary Gln have reduced H. pylori-associated pathology in vivo that is accompanied by beneficial changes in the immune response to H. pylori early in infection. Thus, Gln supplementation may be an alternative therapy for reducing H. pylori-associated pathology.

Amphiregulin-deficient mice develop spasmolytic polypeptide expressing metaplasia and intestinal metaplasia

BACKGROUND & AIMS

The loss of parietal cells from the fundic mucosa leads to the emergence of metaplastic lineages associated with an increased susceptibility to neoplastic transformation. Both intestinal metaplasia (IM) and spasmolytic polypeptide (TFF2/SP) expressing metaplasia (SPEM) have been identified in human stomach, but only SPEM is present in most mouse models of gastric metaplasia. We previously determined that loss of amphiregulin (AR) promotes SPEM induced by acute oxyntic atrophy. We have now examined whether SPEM in the AR-/- mouse predisposes the stomach to gastric neoplasia.

METHODS

Gross pathology of 18-month-old wild-type, AR-/-, and TGF-alpha-/- mice were examined. Ki-67, beta-catenin, Pdx-1, TFF3, and TFF2/SP expression was analyzed by immunohistochemistry. Metaplastic gastric mucosa was analyzed by dual immunostaining for TFF2/SP with MUC2 or TFF3.

RESULTS

By 18 months of age, more than 70% of AR-/- mice developed SPEM while 42% showed goblet cell IM labeled with MUC2, TFF3, and Pdx-1. A total of 28% had invasive gastric lesions in the fundus. No antral abnormalities were observed in AR-/- mice. Metaplastic cell lineages in AR-/- mice showed increases in cell proliferation and cytosolic beta-catenin expression. Dual staining for TFF2/SP with MUC2 or TFF3 showed glands containing both SPEM and IM with intervening cells expressing both TFF2/SP and MUC2 or TFF2/SP and TFF3.

CONCLUSIONS

AR-/- mice develop SPEM, which gives rise to goblet cell IM and invasive fundic dysplastic lesions. The AR-/- mouse represents the first mouse model for spontaneous development of fundic SPEM with progression to IM.