Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We assessed the possible association between CagA+ Helicobacter pylori infection and gastric carcinogenesis in gastric cancer patients. Gastric biopsy specimens were obtained from 64 patients with gastric cancer and were histologically classified into intestinal and diffuse types. H. pylori infection was determined by cultivation, flaA-PCR and serum antibody against CagA. p53, BAX and transforming growth factor-beta-RII (TGFbeta-RII) gene mutations were analyzed by PCR-SSCP and direct sequencing. Intestinal and diffuse types of cancer were detected in 45 and 19 patients, respectively. H. pylori infection was found in 55 (85.9%) of 64 patients. There was no significant difference in H. pylori positivity between intestinal and diffuse types. However, the CagA antibody was positive in 15 (78.9%) of 19 patients with the diffuse type and in 22 (48.9%) of 45 patients with the intestinal type (p = 0.030). Among the 55 H. pylori-positive cases, 11 (29.7%) of the 37 patients in the CagA+ group were found to have p53 alterations, compared with 2 (11.1%) in the 18 CagA- group (p = 0.182). Moreover, among the 64 gastric cancer patients, p53 alterations were more frequently found in the CagA+ group (29.7%) than in the H. pylori-positive CagA- and H. pylori-negative groups (7.4%; p = 0.033). BAX gene mutations were found in 19 (29.7%) of 64 patients and there was no relationship among CagA seropositivity, cancer stages and histopathological phenotypes. In contrast, the TGFbeta-RII gene mutation was only detected in one CagA- patient. The results suggest that CagA+ H. pylori infection may have an important role in the development of gastric cancer patients with p53 mutations
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PMID:Association between CagA+ Helicobacter pylori infection and p53, bax and transforming growth factor-beta-RII gene mutations in gastric cancer patients. 1125 69

The authors studied 46 primary gastric lymphomas for expression of the p53 gene by immunohistochemistry and screened for mutations in p53 exon 5-8 by polymerase chain reaction-single strand conformation polymorphism. Twenty-five specimens cases were also analyzed for loss of heterozygosity (LOH) of chromosomal region 17p12-13.1. In 36 lymphomas negative for Epstein-Barr virus (EBV) infection, of which 29 were of mucosa-associated lymphoid tissue (MALT) type, p53 genetic changes were found in 47.2% but correlated poorly with overexpression. Only 20% of the mutations involved exon 7. There were recurrent mutations of intron 7, intron 6, and exon 6. In contrast, the 10 EBV-positive cases, none of MALT type, had a much higher rate of mutation, and all showed both p53 overexpression and p53 mutation and/or LOH, and 87.5% had mutations involving exon 7. Four of these involved codon 242, not seen in the EBV-negative group. Splicing mutations of intron 8 were seen in three specimens, two involving the same nucleotide position. In four of five specimens, LOH analysis identified microsatellite instability, allelic loss, or both. The Helicobacter pylori infection rate in the EBV-positive group (20%) was much lower than in the EBV-negative group (91.7%). These differences between the two groups suggest involvement of different carcinogens. Mutation of codon 242 has not been specifically associated with other tumors and may represent a mutational hot spot in the EBV-positive lymphomas.
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PMID:Epstein-Barr virus-associated gastric lymphomas are distinct from mucosa-associated lymphoid tissue-type lymphomas: genetic abnormalities of p53 gene. 1155 17

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

The development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma is dependent on Helicobacter pylori infection. Bacterial colonisation of the gastric mucosa triggers lymphoid infiltration and the formation of acquired MALT. The bacterial infection induces and sustains an actively proliferating B-cell population through direct (autoantigen) and indirect (intratumoral T cells specific for H. pylori) immunological stimulation. Moreover, the bacterial infection provokes a neutrophilic response, which causes the release of oxygen free radicals. These reactive species may promote the acquisition of genetic abnormalities and malignant transformation of reactive B cells. A transformed clone carrying the translocation t(1;18)(q21;q21) forms a MALT lymphoma, the growth of which is independent of H. pylori and will not respond to bacterial eradication. Malignant clones without t(11;18)(q21;q21), but with other genetic abnormalities, such as trisomy 3 or microsatellite instability, depend critically on immune stimulation mediated by H. pylori for their clonal expansion. In the early stages, the tumour can be successfully treated by eradication of the bacterium, whereas at later stages the tumour may escape its growth dependency through acquisition of additional genetic abnormalities such as t(1;14)(p22;q32) and t(1;2)(p22,p12) involving the BCL-10 gene. Finally, further genetic abnormalities, such as inactivation of the tumour suppressor genes, p53 and p16, can lead to high-grade transformation. Detection of these abnormalities may help with the clinical management of patients with gastric MALT lymphoma.
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PMID:Gastric MALT lymphoma: from aetiology to treatment. 1190 29

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

Helicobacter pylori infection is the main cause of chronic gastritis. The infection has been linked to altered proliferative activity and changes in various cell cycle regulating proteins. To determine, in a general population sample, the proliferative activity and expression of p53 and p21 in males and females of different age groups with and without H. pylori-associated chronic gastritis, gastric biopsies from 273 subjects (188 with and 85 without H. pylori infection) randomly selected from a general population were examined immunohistochemically for Ki-67, p53, and p21. One thousand epithelial cells, including the surface, neck, and glandular areas, were counted in both the corpus and the antrum. Results are expressed as the percentage of positive cells. Subjects with H. pylori infection showed significantly increased proliferative activity and expression of p53 compared to uninfected individuals. Regarding the expression of p21, no difference was detected. Multiple linear regression analysis showed significant associations between chronic inflammation or inflammatory activity, on the one hand, and the degree of proliferation in both the corpus and the antrum, on the other hand. In the antrum, the degree of H. pylori colonization was related to the expression of p53. H. pylori seems to cause increased proliferation and increased expression of p53 (but not p21) in the gastric mucosa, neither of which is age or sex dependent. The proliferative activity is related mainly to events associated with inflammation, while the expression of p53 in the antrum is associated with the degree of H. pylori infection. The action of p53 appears to be independent of p21 activity.
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PMID:Gastric epithelial proliferation and p53 and p21 expression in a general population sample: relations to age, sex, and mucosal changes associated with H. pylori infection. 1214 17

It has been suggested that certain histological criteria may serve to indicate a good prognosis in patients with esophageal carcinoma. These include absence of subepithelial extension of the carcinoma cells, stage no higher than m2, and no neoplastic involvement near the resection margin. As endoscopic mucosal resection is becoming an accepted treatment option in this type of tumor, prognostic parameters of this type are of particular interest. By contrast, when metastases are detected in the celiac lymph nodes, it implies that the tumor is unresectable and that palliative treatment is required. Endoscopic ultrasound (EUS)-guided fine-needle aspiration has been found to be the most cost-effective option in this setting. Although autofluorescence endoscopy is being tested as a new technique for endoscopic diagnosis, its value is at present unclear. However, such developments may lead to improved diagnosis in the future, particularly in relation to the initial stages of carcinoma. For the moment, EUS is still the most widely accepted method for early diagnosis and staging. Esophageal squamous-cell carcinoma appears to be commonly associated with head and neck cancer, but the cost-effectiveness of surveillance is a matter of controversy. With regard to Barrett's esophagus and adenocarcinoma, p53 staining in areas of low-grade dysplasia appears to be helpful for predicting progression to high-grade dysplasia. The prevalence of short-segment Barrett's esophagus increases with age, but the length of the segment does not increase with time; the length probably depends on individual conditions, not merely on elapsed time. Helicobacter pylori infection appears to be associated with intestinal metaplasia at the esophagogastric junction. However, the most recent data appear to suggest that this scenario (usually termed "carditis") may be different from intestinal metaplasia in the lower esophagus, related to acid reflux. A follow-up program might be able to detect Barrett's esophagus adenocarcinoma at earlier stages, but only a minority of Barrett's esophagus patients are likely to be detected before neoplasia has developed. Gastric cancer appears to develop in individuals with H. pylori infection, but not in uninfected persons. In addition, those with severe gastric atrophy, corpus-predominant gastritis, and intestinal metaplasia may be at greater risk for gastric cancer. This again raises the question of H. pylori eradication in asymptomatic individuals with infection, and surveillance of patients with severe intestinal metaplasia. The most recent data appear to support the notion that healing of MALT lymphoma depends not only on H. pylori eradication and on the stage of the tumor, but also on individual factors (possibly immunology-related).
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PMID:Diagnosis of esophagogastric tumors. 1251 Feb 24

Many epidemiological studies have shown a strong association between chronic Helicobacter pylori infection and subsequent development of gastric carcinoma in humans. To confirm this link more clearly, it is necessary to use this bacterium in experimental studies to develop gastric carcinoma in suitable experimental animals. Persistent H. pylori infection has recently been achieved in the Japanese Monkeys and Mongolian gerbil models, with results demonstrating that the sequential histopathological changes in the gastric mucosa are closely mimic the gastric mucosal changes caused by H. pylori infection in humans. Gastric mucosa infected with H. pylori exhibited significantly higher gastritis score, reduction in glandular height, increase in the number of Ki-67 positive cells and over expression of p53 protein and p53 gene mutation in the Japanese Monkey Model. In the Mongolian gerbil model, H. pylori infection enhances gastric carcinogenesis in combination with known carcinogens such as MNU and MNNG, and also demonstrated that H. pylori infection alone can result in the development of gastric carcinoma. However, diagnostic criteria of gastric carcinoma in animal models remain in the great discussion. These important results provide a starting point for further studies to clarify the mechanism of gastric carcinogenesis as a result of H. pylori infection and assist the planning of eradication therapy to prevent gastric carcinoma.
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PMID:Helicobacter pylori and gastric carcinoma--from the view point of animal model. 1252 42

To determine the prevalence of gastric precancerous lesions and mucosal genetic alterations in relatives of a cluster of familial gastric cancer (FGC), we studied a kindred spanning two generations. The founder, daughter and niece underwent surgery for gastric cancer (GC); a son and other two daughters of the founder, presented with chronic dyspepsia. In all subjects, gastric mucosa samples were analysed for pathological features, Helicobacter pylori infection, microsatellite (MIN) and chromosomal (CIN) instability. The overexpression of mp53 and c-myc, and cytoplasmic beta-catenin delocalisation were found in the 2 younger cancer patients. All GC and gastritis patients had normal E-cadherin expression and were MIN-negative. Aneuploidy characterised all GC cases, and mixed euploid and aneuploid cell populations were present in the gastric biopsies from two of three 'at-risk' relatives. These two subjects, one of whom had severe active gastritis, and gastric mp53 and c-myc expression, were CagA-positive H. pylori-infected. DNA aneuploidy, p53 and c-myc expression disappeared after H. pylori eradication. In this FGC cluster, genetic abnormalities were found in first-degree relatives (3 patients) only in presence of H. pylori infection (2 cases H. pylori-positive versus 1 case H. pylori-negative) supporting the hypothesis that, besides the influence of a genetic profile, FGC may be, at least partly, mediated by intrafamilial clustering of H. pylori infection.
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PMID:Is there a link between environmental factors and a genetic predisposition to cancer? A lesson from a familial cluster of gastric cancers. 1285 70


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