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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The recent demonstration in animal models that H. pylori alone may be capable of inducing intestinal-type gastric cancer, and that H. felis can accelerate gastrin-induced gastric neoplasia has stimulated research on examining the mechanisms of H. pylori-associated carcinogenesis in humans. Several mechanisms are currently under investigation, including the dysregulation of the gastric epithelial cell cycle, the formation of DNA adducts, the generation of free radicals, alterations in growth factor secretion and cytokines, and the effects of decreased gastric acid secretion. This review will examine the relevant evidence acquired from human tissue studies, animal models and cell culture systems in an attempt to explore these pathways, and to evaluate the mechanisms by which H. pylori may cause gastric cancer.
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PMID:The carcinogenic effect of H. pylori on the gastric epithelial cell. 1069 64

Numerous epidemiological studies demonstrated the association between Helicobacter pylori (H. pylori) infection and gastric cancer but the mechanism of the involvement of H. pylori in gastric cancerogenesis remains virtually unknown. This study was designed to determine the seropositivity of H. pylori and cytotoxin associated gene A (CagA), serum gastrin and gastric lumen gastrin levels under basal conditions and following stimulation with histamine in gastric cancer patients and controls. 100 gastric cancer patients aging from 21 to 60 years and 300 gender- and age-adjusted controls hospitalized with non-ulcer dyspepsia (NUD) entered this study. 13C-Urea Breath Test (UBT), serum immunoglobulin (IgG) antibodies to H. pylori and CagA were used to assess the H. pylori infection and serum levels of IL-1beta, IL-8 and TNFalpha were measured by enzyme-linked immunosorbent assay (ELISA) to evaluate the degree of gastric inflammation by H. pylori . Gastrin-17 mRNA and gastrin receptors (CCK(B)) mRNA expression in gastric mucosal samples taken by biopsy from the macroscopically intact fundic and antral mucosa as well as from the gastric tumor was determined using RT-PCR. The overall H. pylori seropositivity in gastric cancer patients at age 21-60 years was about 92%, compared, respectively, to 68%, in controls. A summary odds ratio (OR) for gastric cancer in H. pylori infected patients was about 5.0 . The H. pylori CagA seropositivity in gastric cancer patients was about 58.5% compared to 32.4% in controls, giving the summary OR for gastric cancer in CagA positive patients about 8.0. The prevalence of H. pylori- and H. pylori CagA-seropositivity was significantly higher in cancers than in controls, irrespective of the histology of gastric tumor (intestinal, diffuse or mixed type). Median IL-1beta and IL-8 reached significantly higher values in gastric cancer patients (9.31 and 30.8 pg/ml) than in controls (0.21 and 3.12, respectively). In contrast, median serum gastrin in cancers (as total group) was several folds higher (62.6 pM) than in controls (19.3 pM). Also median luminal gastrin concentration in gastric cancer patients was many folds higher (310 pM) than in controls (20 pM). This study shows for the first time that cancer patients are capable of releasing large amounts of gastrin into the gastric lumen to increase luminal hormone concentration to the level that was recently reported to stimulate the growth of H. pylori. There was no any correlation between plasma gastrin levels and gastric luminal concentration of gastrin suggesting that: 1) luminal gastrin originates from different source than plasma hormone, most probably from the cancer cells, 2) cancer cells are capable of expressing gastrin and releasing it mainly into the gastric juice and 3) the gastric cancer cells are equipped with gastrin-specific (CCK(B)) receptor so they exhibit the self-growth promoting activity in autocrine fashion. This notion is supported by direct detection of gastrin mRNA and gastrin receptor (CCK(B)-receptors) mRNA using RT-PCR in cancer tissue. To our knowledge this is the first study showing an important role of gastrin as self-stimulant of cancer cells in patients infected with H. pylori. Basal and histamine maximally stimulated acid outputs were significantly lower in gastric cancer patients than in controls despite of enhanced gastrin release, particularly in cancer patients and this might reflect the mucosal inflammatory changes (increased serum levels of proinflammtory interleukins - IL-1beta and IL-8), that are known to increase gastrin release. We conclude that: 1) H. pylori infected patients, particularly those showing CagA-seropositivity, are at greatly increased risk of development of gastric cancer, 2) H. pylori-infected cancer patients produce significantly more IL-1beta and IL-8 that might reflect an H. (ABSTRACT TRUNCATED)
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PMID:Role of gastrin in gastric cancerogenesis in Helicobacter pylori infected humans. 1069 65

The effect of gastrin on stimulating tumour proliferation has been evaluated on human pancreas cancer cells in culture and in tumours transplanted to nude mice. The presence of CCK-B/gastrin-like receptor responsible for that effect of gastrin has been proved in colonic (WiDr, HT-29, YAMC) and pancreatic (PANC-1, BON) cell lines. The aim of our study was to examine the stimulating effect of gastrin and pentagastrin on the growth of human gastric adenocarcinoma cell line. The human gastric adenocarcinoma cell line (AGS, CRL-1739) was purchased from ATCC (Rockville, MA, USA). Gastrin-17 was purchased from Sigma-Aldrich (Budapest, Hungary), pentagastrin was from Zeneca Limited (Macclasfield, UK). The cells were incubated in DMEM containing 10% FCS on 96-well culturing plate with 10(4) cells/well starting cell number at 37 degrees C with 5% CO2. The proliferation rates were detected: by the measurements of the metabolically active cells with Owen's reagent and the determination of protein content, and by cell counting in a haemocytometer at several incubation times. As a result, we detected similar proliferation rates using gastrin-17 or pentagastrin in the incubation medium. The stimulating effect of gastrin/pentagastrin on cell line proliferation was in correlation with its concentration. Our results proved that pentagastrin is a 10 times less effective stimulator of proliferation of gastric cancer than gastrin-17, and that AGS human adenocarcinoma cell line might be CCK receptor positive.
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PMID:Gastrin and pentagastrin enhance the tumour proliferation of human stable cultured gastric adenocarcinoma cells. 1076 93

Helicobacter pylori plays major causative roles in peptic ulcer disease and gastric cancer. Elevated acid secretion in patients with duodenal ulcers (DUs) contributes to duodenal injury, and diminished acid secretion in patients with gastric cancer allows carcinogen-producing bacteria to colonize the stomach. Eradication of H. pylori normalizes acid secretion both in hyper-secreting DU patients and hypo-secreting relatives of gastric cancer patients. Therefore, we and others have asked how H. pylori causes these disparate changes in acid secretion. H. pylori gastritis more or less restricted to the gastric antrum in DU patients is associated with increased acid secretion. This is probably because gastritis increases release of the antral acid-stimulating hormone gastrin and diminished mucosal expression of the inhibitory peptide somatostatin. Bacterial products and inflammatory cytokines including TNFalpha may cause these changes in endocrine function. Gastritis involving the gastric corpus tends to diminish acid secretion, probably because bacterial products and cytokines including IL-1 inhibit parietal cells. Pharmacological inhibition of acid secretion increases corpus gastritis in H. pylori-infected subjects, so it is envisaged that gastric hypo-secretion of any cause might become self-perpetuating. H. pylori-associated mucosal atrophy will also contribute to acid hypo-secretion and is more likely in when the diet is high in salt or lacking in antioxidant vitamins. Data on gastric acid secretion in patients with esophagitis are limited but suggest that acid secretion is normal or slightly diminished. Nevertheless, H. pylori infection may be relevant to the management of esophagitis because: (i) H. pylori infection increases the pH-elevating effect of acid inhibiting drugs; (ii) proton pump inhibitors may increase the tendency of H. pylori to cause atrophic gastritis; and (iii) successful eradication of H. pylori is reported to increase the likelihood of esophagitis developing in patients who had DU disease. Points (ii) and (iii) remain controversial and more work is clearly required to elucidate the relationship between H. pylori, acid secretion, gastric mucosa atrophy and esophagitis.
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PMID:Helicobacter pylori modulation of gastric acid. 1078 May 81

Fundic gland polyps (FGPs) are tiny multiple sessile polyps of the acid-secreting gastric mucosa. They have been described both in a sporadic form, mainly in middle-aged females, and in a syndromic form, associated with familial adenomatous polyposis (FAP)-Gardner's syndrome and attenuated variants (AFAP). They share the same histology, characterised by superficial and deep cystic dilatations, shortened gastric pits, with an inconspicuous lamina propria. They have been for a long time described as innocuous lesions, but some recent reports have shown that FGPs may harbour dysplastic foci and ultimately (particularly syndromic polyps) gastric cancer. Factors influencing their genesis are unknown. A circulating factor in FAP patients has been postulated and a role of female hormones has been suggested for sporadic FGPs. Whereas patients with sporadic FGPs have normal basal acid output, normal fast serum levels of gastrin and pepsinogen I, the role of gastrin seems crucial for the development of cystic changes in flat body-fundus mucosa, and for the appearance of FGPs in patients with Zollinger-Ellison syndrome. A role of H. pylori induced gastritis has been excluded. Actually, patients with both sporadic and syndromic FGPs appear consistently free from H. pylori colonisation, again for an unknown factor(s). Some recent reports have claimed a role for omeprazole in the genesis of FGPs, a highly controversial issue. Ultimately, the nature of FGPs is still debated: some have interpreted them as hamartomatous lesions, others as a peculiar form of hyperplastic polyp.
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PMID:Fundic gland polyps: a still elusive entity on the eve of the year 2000. 1083 97

Altered gastrin expression associated with Helicobacter pylori infection may contribute to the pathogenesis of peptic ulcer disease or gastric cancer in man, but gastrin has not been investigated in a murine model of Helicobacter infection. C57BL/6 mice were inoculated with Helicobacter felis and examined after 4-21 weeks for G and D cell numbers, antral gastrin and somatostatin mRNA, and luminal pH. In H. felis-infected mice, gastrin mRNA declined at four and six weeks after infection to 57% and 23%, respectively, of uninfected control values. Concurrently, somatostatin mRNA showed no change at four weeks and a modest 25% decrease at six weeks after infection. Similar reductions were noted in G and D cell numbers, resulting in a decrease in the G/D cell ratio after mice were infected with H. felis. Infected animals also showed a loss of parietal and chief cells, and an increased gastric pH. H. felis infection in C57BL/6 mice leads to an early suppression of G cell number and gastrin mRNA. These changes precede an alteration in somatostatin cell number and mRNA and, coupled with reductions in parietal and chief cells, may contribute both to severe impairment of gastric acid output and the potential for carcinogenic processes.
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PMID:Altered gastrin regulation in mice infected with Helicobacter felis. 1096 8

Helicobacter pylori (H.p.) causes active chronic gastritis in nearly all infected patients. Cytotoxic factors elaborated by H.p. as well as autoimmune cell damage from the abundant inflammatory response contribute to gastric epithelial cell injury. Antrum gastritis increases gastrin release. The impact of H.p.-infection on gastric acid physiology is complex and usually results in increased gastric acid secretion in duodenal ulcer patients and diminished acid output in patients with gastric cancer. Multiple clinical outcomes including asymptomatic gastritis, duodenal ulcer, gastric ulcer, gastric carcinoma and gastric MALT lymphoma are associated with H.p.-infection. Differences in disease manifestation seem to result from a complex interaction of bacterial virulence, host factors as well as environmental factors. The acid-secretory ability of the infected individual seems to be the main variable determining outcome: Patients with high acid production typically develop antrum-predominant gastritis and are at an increased risk for duodenal ulcer. In contrast patients with low gastric acid secretion frequently develop pangastritis, which may progress to chronic atrophic gastritis and carcinoma.
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PMID:[Physiopathology of Helicobacter pylori infections]. 1098 80

Gastrin is a growth factor for colorectal cancer, and therefore, anti-gastrin hormone therapy has a potential role in treatment of this disease. The gastrin immunogen gastrin-17-diphtheria toxoid (G17-DT; Gastrimmune) produces anti-G17 antibodies that have been shown to be effective in the treatment of colorectal carcinoma in preclinical models. Fifty patients with advanced colorectal cancer were treated with G17-DT in a multicenter, sequential group, open label Phase I/II study. Primary injections with two booster doses were given by i.m. injection. The main aim of the study was to assess the safety and efficacy of the production of antigastrin antibodies. Locally developed and standard WHO toxicity measurements with RIA and Scatchard analysis for antibody assessment were used. One center measured tumor response radiologically. Eighty % of patients produced a measurable antibody response. Antibodies of high affinity (median Kd, 0.295 nM; interquartile range, 0.16-0.41 nM) were detected between 4 and 12 weeks after primary injection. The antigen binding capacity was high at 2.8 x 10(-9) M (interquartile range, 5.1 x 10(-10) to 7.25 x 10(-9) M). The treatment was well tolerated with no systemic side effects seen. Myalgia at the injection site was seen in 46% of patients with severe pain caused by the formation of a sterile abscess seen in 14% of patients. The abscesses were all drained under ultrasound guidance, and the patients recovered fully within 6 weeks. No radiological responses were seen, but two patients had stable disease. G17-DT immunization produces anti-G17 antibodies in patients with advanced colorectal cancer. The antibodies were of an affinity high enough to compete with the cholecystokinin B/gastrin receptor for G17 binding with adequate capacity to neutralize postprandial gastrin surges. Additional dose-ranging studies have been performed in patients with gastric cancer using 100- and 200-microg doses of G17-DT formulated without adjuvant and the emulsifier aluminum monostearate. In addition, the effect of immunizing at different time intervals has been determined.
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PMID:Phase I/II study of G17-DT, an anti-gastrin immunogen, in advanced colorectal cancer. 1115 25

Gastric epithelial organization and function are controlled and maintained by a variety of endocrine and paracrine mediators. Peptides encoded by the gastrin gene are an important part of this system because targeted deletion of the gene, or of the gastrin-CCKB receptor gene, leads to decreased numbers of parietal cells and decreased gastric acid secretion. Recent studies indicate that the gastrin precursor, preprogastrin, gives rise to a variety of products, each with a distinctive spectrum of biological activity. The conversion of progastrin to smaller peptides is regulated by multiple mechanisms including prohormone phosphorylation and secretory vesicle pH. Progastrin itself stimulates colonic epithelial proliferation; biosynthetic intermediates (Gly-gastrins) stimulate colonic epithelial proliferation and gastric epithelial differentiation; and C-terminally amidated gastrins stimulate colonic proliferation, gastric epithelial proliferation and differentiation, and acid secretion. The effects of progastrin-derived peptides on gastric epithelial function are mediated in part by release of paracrine factors that include histamine, epidermal growth factor (EGF)-receptor ligands, and Reg. The importance of the appropriate regulation of this system is shown by the observation that prolonged moderate hypergastrinemia in transgenic mice leads to remodelling of the gastric epithelium, and in the presence of Helicobacter, to gastric cancer.
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PMID:The gastrins: their production and biological activities. 1118 51

Intestinal-type gastric adenocarcinomas usually are preceded by chronic atrophic gastritis. Studies of gastric cancer prevention often rely on identification of this condition. In a clinical trial, we sought to determine the best serological screening method for chronic atrophic gastritis and compared our findings to the published literature. Test characteristics of potential screening tests (antibodies to Helicobacter pyloni or CagA, elevated gastrin, low pepsinogen, increased age) alone or in combination were examined among consecutive subjects enrolled in a study of H. pylori and preneoplastic gastric lesions in Chiapas, Mexico; 70% had chronic atrophic gastritis. English-language articles concerning screening for chronic atrophic gastritis were also reviewed. Sensitivity for chronic atrophic gastritis was highest for antibodies to H. pylori (92%) or CagA, or gastrin levels >25 ng/l (both 83%). Specificity, however, was low for these tests (18, 41, and 22%, respectively). Pepsinogen levels were highly specific but insensitive markers of chronic atrophic gastritis (for pepsinogen I <25 microg/l, sensitivity was 6% and specificity was 100%; for pepsinogen I:pepsinogen II ratio <2.5, sensitivity was 14% and specificity was 96%). Combinations of markers did not improve test characteristics. Screening test characteristics from the literature varied widely and did not consistently identify a good screening strategy. In this study, CagA antibodies alone had the best combination of test characteristics for chronic atrophic gastritis screening. However, no screening test was both highly sensitive and highly specific for chronic atrophic gastritis.
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PMID:Screening markers for chronic atrophic gastritis in Chiapas, Mexico. 1121 66


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