3-nitrotyrosine and Stomach-Neoplasms

Investigation of urinary markers as indices of endogenous nitrosation and of gastric cancer etiology has been a major focus of our work. As part of this effort, studies have been carried out on a Colombian population at high risk for gastric cancer. In this group, nitrosoproline excretion was highly correlated with nitrate excretion in the subpopulation with advanced gastric pathology, but not in control subpopulations with more normal stomachs. Neither urinary 7-methylguanine nor 3-methyladenine was strongly related to gastric pathology or to urinary nitrate or nitrosoproline levels. More recently, as evidence has accumulated concerning the importance of nitric oxide as a cellular messenger, we have begun research toward developing markers for the presence of nitric oxide and for endogenous nitrosation via this compound. Nitric oxide is formed from arginine by activated endothelial cells as a messenger for vasodilation. We have shown that prolonged exercise leads to increased urinary nitrate and that when 15N-arginine is ingested by humans, 15N-nitrate levels increase in 24-hr urine collections. Nitrosohydroxyethylglycine and 3-nitrotyrosine were evaluated as indices for the formation of N-nitrosomorpholine and for the nitration of protein, respectively, under experimental conditions (e.g., immunostimulation) expected to enhance nitric oxide formation. Nitrotyrosine has not proved useful as a biomarker for nitration/nitrosation reactions in immunostimulated rats. Immunostimulation of rats following administration of morpholine led to increases in urinary nitrate and nitrosohydroxyethylglycine. This procedure, however, would not be appropriate for humans due to the toxicity of morpholine and the carcinogenicity of N-nitrosomorpholine.

Topics: Adenine; Alkylating Agents; Animals; Biomarkers; Dimethylnitrosamine; DNA Damage; Humans; Nitric Oxide; Nitrosamines; Nitroso Compounds; Risk Factors; Stomach Neoplasms; Tyrosine

To establish the role of oxidative stress and v-akt murine thymoma viral oncogene homolog (AKT) activation in gastric cancer development, we examined the levels of phosphorylated AKT (pAKT), inducible nitric oxide synthase (iNOS), nitrotyrosine (NT), and human telomerase reverse transcriptase (hTERT) by enzyme-linked immunosorbent assay in 73 non-cancerous gastric mucosa and 10 gastric carcinomas. We found that the levels of pAKT were associated with the levels of iNOS, NT, and hTERT. Gastric mucosa was classified into four categories: chronic gastritis without Helicobacter pylori (CG), chronic active gastritis with H. pylori (CAG), chronic metaplastic gastritis without H. pylori (CMG), and chronic gastritis with atypia without H. pylori (CGA). We found increasing levels of pAKT, iNOS, and NT in the order of CG, CAG, CMG, and CGA. hTERT was detected only in CGA. These findings suggest that oxidative stress might be associated with AKT activation and hTERT induction and that mucosa in CGA might confer a high-risk status for gastric carcinogenesis.

Topics: Cell Line, Tumor; Gastric Mucosa; Humans; Nitric Oxide; Nitric Oxide Synthase Type II; Phosphorylation; Proto-Oncogene Proteins c-akt; Risk Factors; Stomach Neoplasms; Telomerase; Tyrosine

To investigate the extent of oxidative stress in pre-neoplastic and neoplastic gastric mucosa in relation to their pathological criteria and histological subtypes.. A total of 104 gastric adenocarcinomas from 98 patients (88 infiltrative and 16 intraepithelial tumors) were assessed immunohistochemically for expression of iNOS and occurrence of nitrotyrosine (NTYR)-containing proteins and 8-hydroxy-2'-deoxyguanosine (8-OH-dG)-containing DNA, as markers of NO production and damages to protein and DNA.. Tumor cells staining for iNOS, NTYR and 8-OH-dG were detected in 41%, 62% and 50% of infiltrative carcinoma, respectively. The three markers were shown for the first time in intraepithelial carcinoma. The expression of iNOS was significantly more frequent in tubular carcinoma (TC) compared to diffuse carcinoma (DC) (54% vs 18%; P = 0.008) or in polymorphous carcinoma (PolyC) (54% vs 21%; P = 0.04). NTYR staining was obviously more often found in TC than that in PolyC (72% vs 30%; P = 0.03). There was a tendency towards a higher rate of iNOS staining when distant metastasis (pM) was present. In infiltrative TC, the presence of oxidative stress markers was not significantly correlated with histological grade, density of inflammation, the depth of infiltration (pT), lymph nodes dissemination (pN) and pathological stages (pTNM).. The iNOS-oxidative pathway may play an important role in TC, but moderately in PolyC and DC. DNA oxidation and protein nitration occur in the three subtypes. Based on the significant differences of NTYR levels, TC and PolyC appear as two distinct subtypes.

Topics: Adenocarcinoma; Adult; Aged; Aged, 80 and over; Biomarkers; Carcinoma in Situ; Deoxyguanine Nucleotides; DNA, Neoplasm; Female; Gastric Mucosa; Humans; Immunohistochemistry; Male; Middle Aged; Neoplasm Proteins; Nitric Oxide; Nitric Oxide Synthase Type II; Oxidative Stress; Precancerous Conditions; Retrospective Studies; Stomach Neoplasms; Tyrosine

Epidemiological studies show that high intake of food-bound vitamin C and E reduces the risk of gastric cancer. Whether dietary supplementation with antioxidant micronutrients interferes with Helicobacter pylori infection and associated diseases is unclear. The aim of this study was to investigate if dietary vitamin C or E supplementation influences the progression of gastritis, gastric mucosal nitrosative and oxidative protein damage, gastric mucosal lipid peroxidation, or gastric mucosal oxidative DNA damage in H. pylori-infected Mongolian gerbils.. Gerbils were divided into four groups: H. pylori-infected animals fed with vitamin C- or vitamin E-supplemented food, and infected and uninfected animals given standard rodent food. Subgroups of animals were killed at different time-points until 52 weeks postinfection. Concentrations of 3-nitrotyrosine and thiobarbituric acid-reactive substances (TBARS) in the gastric mucosa were determined with an immunodot blot and a fluorometric method, respectively. Mucosal concentrations of carbonyl carbons on proteins and 8-hydroxydeoxyguanosine were determined by enzyme-linked immunosorbent assay. Gastritis was scored semiquantitatively.. Vitamin supplements had no effect on the colonization with H. pylori. Vitamin C as well as vitamin E supplements reduced mucosal 3-nitrotyrosine concentrations to normal levels in infected animals. Vitamin E supplements decreased mucosal protein carbonyls and TBARS in short-term gastritis. In addition, vitamin C supplements caused attenuated mucosal oxidative DNA damage and milder mucosal inflammation in short-term gastritis.. Vitamin C or vitamin E supplementation leads to some short-term protective effects on H. pylori-induced gastritis in Mongolian gerbils. These effects seem to subside over time when the infection persists.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Ascorbic Acid; Deoxyguanosine; Dietary Supplements; Disease Models, Animal; Gastric Mucosa; Gastritis; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Male; Stomach Neoplasms; Thiobarbituric Acid Reactive Substances; Tyrosine; Vitamin E; Vitamins

To detect the presence of inducible nitric oxide synthase (iNOS), nitrotyrosine (NT) and apoptosis in gastric adenocarcinomas and their possible correlations with the clinicopathological characteristics and prognosis of gastric adenocarcinoma.. Sixty-six specimens of gastric adenocarcinoma and corresponding adjacent normal gastric tissues were studied. Immunohistochemistry was employed to localize iNOS and NT protein and an immunohistochemical scoring system was used. The occurrence of apoptotic cell death (apoptotic index (AI)) was analyzed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling (TUNEL) method.. Results showed that iNOS expression was detected at an intermediate or high level in 41 of 66 (62%) specimens of gastric adenocarcinoma. NT expression was 58%. Neither of them was found in the normal gastric tissues; there were significant positive correlations among iNOS expression, NT expression and AI. Many clinicopathologic characteristics of gastric adenocarcinoma, such as tumor size, depth of invasion, lymph node metastasis and TNM staging, were related to iNOS and NT expressions (P<0.05). In 66 surviving patients, the 5-year survival rate of 41 patients who had tumors with intermediate or high iNOS expressions and high AIs (4.09%; 19.96%) was significantly lower than that of 25 patients who had tumors with negative or low iNOS expressions and low AIs (0.79%; 47.14%) (P = 0.001). COX's multivariate analysis revealed that the iNOS expression was identified as one of the significant independent prognostic factors predictive of a poor survival (relative risk (RR) = 2.69).. NO produced by iNOS may play a stronger role in promoting gastric adenocarcinoma growth than in suppressing its growth. iNOS and NT expressions by gastric adenocarcinoma may correlate with a poor survival.

Topics: Adenocarcinoma; Adult; Aged; Apoptosis; Female; Humans; Male; Middle Aged; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Stomach Neoplasms; Survival Analysis; Tyrosine

Overproduction of nitric oxide via inducible nitric oxide synthase (iNOS) is suggested to be a significant pathogenic factor in Helicobacter pylori induced gastritis. The purpose of this study was to examine the role of iNOS in H pylori associated gastric carcinogenesis.. Two types of mice were used in this study: iNOS deficient mice (iNOS-/-) and wild-type littermates. Gastric cancer was generated in mice using a combination treatment comprising N-methyl-N-nitrosourea administration and H pylori infection. Fifty weeks after treatment, tumours in gastric tissues from both types of mice were examined using histopathology, immunohistochemistry, and immunoblotting for iNOS and 3-nitrotyrosine.. The overall incidence of gastric cancer at week 50 was significantly lower in iNOS-/- compared with iNOS wild-type mice (p<0.05). When analysed according to tumour pathology, the incidence of gastric adenocarcinoma was significantly lower in iNOS-/- compared with iNOS wild-type mice (p<0.05). Immunostaining for iNOS was clearly observed in adenocarcinoma cells of iNOS wild-type mice, and was characterised by a strong cytoplasmic expression pattern. 3-Nitrotyrosine was expressed mostly in the area of the lamina propria of gastritis and adenoma lesions in iNOS wild-type mice. Immunoblotting analyses showed that iNOS and 3-nitrotyrosine were also expressed in both adenoma and adenocarcinoma tissues from iNOS wild-type mice. iNOS and 3-nitrotyrosine expression was greater in tumour tissues than in non-tumour tissues.. These findings suggest that iNOS contributes to H pylori associated gastric carcinogenesis in mice.

Topics: Adenocarcinoma; Adenoma; Animals; Cell Transformation, Neoplastic; Gastric Mucosa; Gastritis; Helicobacter Infections; Helicobacter pylori; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Stomach; Stomach Neoplasms; Tyrosine

Recent studies (K. Komoto et al., Am. J. Gastroenterol., 93: 1271-1276, 1998) have shown that Helicobacter pylori infection is associated with gastric cancer. However, the mechanism of H. pylori in carcinogenesis has not been clarified. H. pylori infection leads to a sustained production of reactive nitrogen species that may contribute to cause DNA damage. In this study, we examined the expression of inducible nitric oxide synthase (iNOS) and nitrotyrosine in gastric mucosa. The expression of iNOS and nitrotyrosine was examined by immunohistochemistry in 93 patients who initially underwent gastric biopsies between 1975 and 1992. Thirty-four individuals were later found to have gastric cancer at least 2 years after the initial biopsies (group A). The other 59 subjects have shown no evidence of gastric cancer during long-term follow-up. Fifty-one of these patients were positive for H. pylori (group B), and eight were negative for H. pylori (group C). The expression of iNOS and nitrotyrosine in the gastric mucosa was significantly higher in H. pylori-positive groups A and B than in H. pylori-negative group C. Among the H. pylori-positive patients, the expression of iNOS and nitrotyrosine was significantly higher in group A than in group B. These results suggest that high production of iNOS and nitrotyrosine in the gastric mucosa infected with H. pylori may contribute to the carcinogenesis of gastric cancer.

Topics: Adult; Aged; Female; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Humans; Immunohistochemistry; Male; Middle Aged; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Stomach Neoplasms; Tyrosine