Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to study the role of Helicobacter pylori infection in gastric carcinogenesis, we have measured oxidized (carbonyls) and nitrated (nitrotyrosine-containing) proteins as markers for oxidative and nitrative stress in 216 human gastric biopsies using dot and western immunoblots and correlated the results with H. pylori, cagA status, expression of interleukin-8 and inducible nitric oxide synthase (iNOS) mRNAs, and gastric pathology. Higher levels of both oxidized and nitrated proteins were found in patients with either chronic gastritis or duodenal ulcer than in those with normal mucosa. The levels of modified proteins were significantly higher in inflamed samples infected with H. pylori, especially cagA+ strains, and in those with expression of interleukin-8 and iNOS mRNAs than in those negative for these parameters. These results indicate that infection with cagA+ H. pylori induces significant oxidative and nitrative stress in stomach mucosa, contributing to the pathogenesis of H. pylori-associated gastroduodenal diseases.
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PMID:Increased oxidative and nitrative stress in human stomach associated with cagA+ Helicobacter pylori infection and inflammation. 1133 Apr 21

Dysfunction of E-cadherin and catenin has been linked to invasiveness and differentiation of tumors. This study aimed to characterize the expression of cadherins and catenins in early gastric carcinoma and their relationship to clinicopathologic characteristics and Helicobacter pylori infection. E-cadherin and alpha-, beta- and gamma-catenins were strongly expressed in normal epithelium but abnormal immunoreactivity of at least one of these four proteins was noted in 48 (90.6%) of 53 early gastric carcinomas. Only 5 cases with intestinal-type tumors had intact expression of E-cadherin and alpha-, beta-, and gamma-catenins. Abnormal immunoreactivity in the tumor tissue was observed in 18 patients (34.0%) for E-cadherin, in 35 (66.0%) for alpha-catenin, in 20 (37.7%) for beta-catenin, and in 37 (69.8%) for gamma-catenin. In diffuse-type tumors, abnormal expression of E-cadherin (60.9 vs. 13.3%, p < 0.0005), alpha-catenin (82.6 vs. 53.3%, p < 0.05) and gamma-catenin (91.3 vs. 53.3%, p < 0.005) was more frequent than in the intestinal type. Ten tumors with lymph node metastasis showed a relatively higher frequency of abnormal expression of E-cadherin (70 vs. 25.6%, p < 0.05) but a lower frequency of abnormal expression of beta-catenin (10 vs. 44.1%, p = 0.07) than those without metastasis. No significant association was found between cadherin/catenin expression and the depth of invasion or the H. pylori status. It was concluded that abnormal expression of E-cadherin and the catenin-mediated cell-cell adhesion system occurs frequently in early gastric carcinogenesis and may play an important role in the genesis of histologic differentiation and in the mode of metastasis of early gastric carcinomas.
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PMID:Immunohistochemical evaluation of cadherin and catenin expression in early gastric carcinomas: correlation with clinicopathologic characteristics and Helicobacter pylori infection. 1140 2

Considering a suspected link between Helicobacter pylori infection and human stomach cancer, a new H. pylori gene for membrane protein 1 (HP-MP1) was recently cloned. Because HP-MP1 induces release of inflammatory cytokines and tumor necrosis factor-alpha acts as both initiator and tumor promoter, we studied the possible involvement of HP-MP1 in carcinogenesis of H. pylori. Two cell lines, BALB/3T3 cells as control and v-Ha-ras-transfected BALB/3T3 cells (Bhas 42 cells) as putative initiated cells, were each transfected with HP-MP1, urease B genes, or vector alone. All of the Bhas/mpl clones showed strong expression of tumor necrosis factor-alpha gene and produced tumors in 100% of nude mice. Two Bhas/ure clones showed weak tumorigenicity; the other Bhas and BALB clones showed none. Results indicate strong carcinogenic activity of HP-MP1 in cooperation with viral Ras protein and weak activity of urease B.
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PMID:Helicobacter pylori membrane protein 1: a new carcinogenic factor of Helicobacter pylori. 1152 25

WNT10A and WNT10B genes are human orthologues of mouse proto-oncogene Wnt-10b. We have previously cloned and characterized WNT10A, and demonstrated up-regulation of WNT10A by tumor necrosis factor alpha (TNFalpha) in gastric cancer. Here, we cloned and characterized human WNT10B, which showed Gly60Asp amino-acid substitution compared with human WNT10B previously reported by another group. Gly60 WNT10B allele was identified in 2 human genome draft sequences and 7 human ESTs, while Asp60 WNT10B allele was not identified in any human genome draft sequences or ESTs. The Gly60-type WNT10B cDNA isolated in this study might be derived from more common WNT10B allele. WNT10B was most homologous to WNT10A (64.5% total amino-acid identity) among human WNTs. Variable region in the WNT core domain of WNT10B and WNT10A were longer than that of other WNTs, such as WNT2B1, WNT2B2, WNT3, WNT3A, WNT5B, WNT7B, WNT8A, WNT11, WNT14, and WNT14B/WNT15. We next investigated expression of WNT10B in human gastric cancer. WNT10B was moderately expressed in MKN45 and MKN74 cells, and weakly expressed in Okajima, TMK1, MKN7, MKN28, and KATO-III cells. Because interferon gamma (IFNgamma) and TNFalpha were frequently elevated in gastric mucosa with Helicobacter pylori infection, effects of IFNgamma and TNFalpha on WNT10B expression in MKN45 cells were investigated. TNFalpha induced transient up-regulation of WNT10B mRNA in MKN45 cells. Up-regulation of WNT10B in human gastric mucosa might lead to gastric carcinogenesis through activation of the beta-catenin - TCF signaling pathway, just like up-regulation of Wnt-10b in mouse mammary gland leads to mammary carcinogenesis.
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PMID:Proto-oncogene WNT10B is up-regulated by tumor necrosis factor alpha in human gastric cancer cell line MKN45. 1171 88

Both genetic and epigenetic alterations of tumor suppressor and tumor-related genes involved in the pathogenesis of gastric cancer are reviewed here, and molecular pathways of gastric carcinogenesis are proposed. Gastric carcinomas are believed to evolve from native gastric mucosa or intestinal metaplastic mucosa that undergoes genetic and epigenetic alterations involving either the suppressor pathway (defects in tumor suppressor genes) or mutator pathway (defects in DNA mismatch repair genes). Methylation of E-cadherin in native gastric mucosa results in undifferentiated carcinomas (suppressor pathway), while methylation of hMLHI results in differentiated foveolar-type carcinomas (mutator pathway). The majority of differentiated gastric carcinomas however, arise from intestinal metaplastic mucosa and exhibit structural alterations of tumor suppressor genes, especially p53. They appear to be related to chronic injury, perhaps due to Helicobacter pylori infection. Approximately 20% of differentiated carcinomas (ordinary-type) have evidence of mutator pathway tumorigenesis. Mutations of E-cadherin are mainly involved in the progression of differentiated carcinomas to undifferentiated tumors. The molecular pathways of gastric carcinogenesis depend on the histological background, and gastric carcinomas show distinct biological behaviors as a result of discernible cellular genetic and epigenetic alterations.
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PMID:Genetic and epigenetic alterations of tumor suppressor and tumor-related genes in gastric cancer. 1181 81

Although it is fairly well accepted that Helicobacter pylori infection plays a significant role in causing gastric cancer, the exact mechanisms involved in its pathogenesis are unclear. We have examined the relationship between H. pylori infection and oncogene expression in different stages of disease progression from precursor lesions to gastric carcinoma. We used Diff-Quik stain to diagnose H. pylori infection and immunohistochemical stains against c-erbB-2, p53, ras, c-myc, and bcl-2 to determine expression of oncogenes. H. pylori infection was found in all cases of chronic gastritis, atrophic gastritis, intestinal metaplasia, and early gastric carcinoma, and in 16 of 30 (53%) cases of advanced gastric carcinoma. Overexpression of c-erbB-2 was found in 2 (7%) cases of advanced gastric carcinoma, which were H. pylori negative. Suppressor gene, p53, was overexpressed in 3 (30%) cases of intestinal metaplasia, 2 (33%) cases of early gastric carcinoma, and 18 (60%) cases of advanced gastric carcinoma. Of these 18 p53-positive advanced gastric cancer cases, 11 (61%) were H. pylori positive. Expression of ras p21 was found in 4 (40%) cases of H. pylori-negative normal mucosa, 10 (100%) cases of chronic gastritis, 1 (10%) case of atrophic mucosa, 6 (60%) cases of intestinal metaplasia, 2 (33%) cases of nonneoplastic mucosa adjacent to early gastric carcinoma, and 7 (23%) nonneoplastic mucosa adjacent to advanced gastric carcinoma, all of which showed H. pylori. No evidence of expression of either c-myc or bcl-2 was detected in any of the above-mentioned samples. The data suggest that H. pylori infection may increase expression of ras p21 proteins and induce p53 suppressor gene mutation early in the process of gastric carcinogenesis.
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PMID:Helicobacter pylori infection and oncogene expressions in gastric carcinoma and its precursor lesions. 1183 9

BACKGROUND: We conducted a case-control study to evaluate whether patients with severe gastric atrophy (indicated by serum pepsinogen concentration) have a high risk of gastric cancer.METHODS: At the time of diagnosis of gastric cancer, sera from 301 patients (cases) and 602 sex- and age-matched cancer-free individuals (controls) were tested for the presence of anti- Helicobacter pylori IgG antibody (HM-CAP enzyme-linked immunoassay [ELISA] kit; Kyowa Medix, Tokyo, Japan) and serum pepsinogen (PG) levels (PG I and II Riabead Kits; Dainabot, Tokyo, Japan). We defined positivity for pepsinogen a pepsinogen I concentration of less than 70 ng/mL and a PG I/II ratio of less than 3.0. We categorized the subjects according to serum pepsinogen levels and anti- Helicobacter pylori IgG antibody, creating four categories.RESULTS: Of the 301 cancer cases, 177 had positive serum pepsinogen levels, and 172 were positive for anti- Helicobacter pylori IgG antibody. The category in which subjects had positive serum pepsinogen levels and were negative for anti- Helicobacter pylori IgG antibody had the highest proportion (76.9%) of individuals with gastric cancer and the highest odds ratio (4.20) of the four categories. The odds ratios were 2.55 (95% confidence interval; 1.92-3.88) for positive serum pepsinogen levels and 0.93 (95% confidence interval; 0.63-1.27) for positive anti- Helicobacter pylori IgG antibody.CONCLUSION: These results suggest that patients with positive serum pepsinogen levels who are negative for IgG antibody to Helicobacter pylori, constitute a high-risk group for gastric cancer. Helicobacter pylori infection is associated with the development of gastric cancer by providing a suitable environment i.e., severe gastric atrophy, for carcinogenesis of the gastric mucosa.
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PMID:Severe atrophic gastritis with Helicobacter pylori infection and gastric cancer. 1195 55

Both HLA-DQA1 and -DQB1 genes and Helicobacter pylori infection have been linked to gastric cancer. The aim of this work was to determine if HLA-DQA1 and -DQB1 alleles are presented at altered frequency in Italian patients with gastric adenocarcinoma and H. pylori infection. Oligotyping for HLA-DQA1 and -DQB1 and H. pylori serology was performed for 50 patients with gastric adenocarcinoma and compared with 80 patients with colonic adenocarcinoma and 179 healthy subjects. H. pylori infection was present in 76% of gastric cancer patients, 77.5% of colonic cancer patients, and 72% of controls. The prevalence of infection was not significantly different in the three groups of subjects sorted according to their HLA-DQA1 or -DQB1 status. Apart from HLA-DQA1* 0201, which was less common in patients with colonic carcinoma than controls, no other HLA-DQA1 and no HLA-DQB1 allele were present at altered frequency in patients with gastric or colonic cancer. Neither anatomical location and histological type of cancer nor the presence of lymph node or distant metastases were significantly associated with specific HLA-DQA1 or -DQB1 alleles or H. pylori infection. Both HLA-DQA1 and -DQB1 genes have a minor, if any, role in H. pylori infection and gastric carcinogenesis.
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PMID:HLA-DQA1 and -DQB1 genes and Helicobacter pylori infection in Italian patients with gastric adenocarcinoma. 1197 82

To study the status of oxidative DNA damage in Helicobacter pylori infection in more detail, we examined oxidative DNA damage to individual genes by determining the loss of PCR product of a targeted gene before and after gastric mucosal DNA was treated with 8-hydroxyguanine glycosylase, which cleaves DNA at the 8-hydroxyguanine residues. The results showed that, of the 5 genes tested, p53, insulin-like growth factor II receptor and transforming growth factor-beta receptor type II showed significant oxidative DNA damage in H. pylori-positive tissues and that the BAX and beta-ACTIN genes were relatively undamaged. These results suggest that in H. pylori infection, oxidative DNA damage does not occur homogeneously throughout the genomic DNA but, rather, in a gene-specific manner. We conclude that the progressive accumulation of preferential oxidative DNA damage in certain genes, such as p53, likely contributes to gastric carcinogenesis.
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PMID:Gene-specific oxidative DNA damage in Helicobacter pylori-infected human gastric mucosa. 1199 37

Inducible NO synthase (iNOS) expression and production of NO are both up-regulated with Helicobacter pylori infection in vivo and in vitro. We determined whether major pathogenicity proteins released by H. pylori activate iNOS by coculturing macrophages with wild-type or mutant strains deficient in VacA, CagA, picB product, or urease (ureA(-)). When filters were used to separate H. pylori from macrophages, there was a selective and significant decrease in stimulated iNOS mRNA, protein, and NO(2)(-) production with the ureA(-) strain compared with wild-type and other mutants. Similarly, macrophage NO(2)(-) generation was increased by H. pylori protein water extracts of all strains except ureA(-). Recombinant urease stimulated significant increases in macrophage iNOS expression and NO(2)(-) production. Taken together, these findings indicate a new role for the essential H. pylori survival factor, urease, implicating it in NO-dependent mucosal damage and carcinogenesis.
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PMID:Cutting edge: urease release by Helicobacter pylori stimulates macrophage inducible nitric oxide synthase. 1205 7


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