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Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals.

ABSTRACT: Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revolutionized the understanding of gastric carcinogenesis. This includes the tumour microenvironment, germline mutations, and the role of Helicobacter pylori bacteria, Epstein Barr virus and epigenetics in somatic mutations. There is evidence that ascorbic acid, phytochemicals and endogenous antioxidant systems can modify the risk of gastric cancer. Gastric juice ascorbate levels depend on dietary intake of ascorbic acid but can also be decreased by H. pylori infection, H. pylori CagA secretion, tobacco smoking, achlorhydria and chronic atrophic gastritis. Ascorbic acid may be protective against gastric cancer by its antioxidant effect in gastric cytoprotection, regenerating active vitamin E and glutathione, inhibiting endogenous N-nitrosation, reducing toxic effects of ingested nitrosodimethylamines and heterocyclic amines, and preventing H. pylori infection. The effectiveness of such cytoprotection is related to H. pylori strain virulence, particularly CagA expression. The role of vitamin C in epigenetic reprogramming in gastric cancer is still evolving. Other factors in conjunction with vitamin C also play a role in gastric carcinogenesis. Eradication of H. pylori may lead to recovery of vitamin C secretion by gastric epithelium and enable regression of premalignant gastric lesions, thereby interrupting the Correa cascade of gastric carcinogenesis.

SUBMITTER: Toh JWT

PROVIDER: S-EPMC7503565 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals.

Toh James W T JWT Wilson Robert B RB

International journal of molecular sciences 20200903 17

Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revol ...[more]

PMID: 32899442

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Project description:BACKGROUND & AIMS: Gastric cancer results from a combination of Helicobacter pylori (H pylori) infection, exposure to dietary carcinogens, and predisposing genetic make-up. Because the role of these factors in gastric carcinogenesis cannot be determined readily in human beings, the present study examined the role of an oral carcinogen and H pylori infection in rhesus monkeys. METHODS: Gastroscopies were performed in 23 monkeys assigned to 4 groups: controls; nitrosating carcinogen ethyl-nitro-nitrosoguanidine administration alone; and inoculation of a virulent H pylori strain alone (H), or in combination with ethyl-nitro-nitrosoguanidine (EH). Follow-up gastroscopies and biopsies were performed at 3-month intervals for 5 years for pathologic and molecular studies. RESULTS: Postinoculation, H and EH groups showed persistent infection and antral gastritis. Starting at 2 and 5 years, respectively, gastric intestinal metaplasia and intraepithelial neoplasia developed in 3 EH monkeys but in no other groups. Transcriptional analysis of biopsies at 5 years revealed group-specific expression profiles, with striking changes in EH monkeys, plus a neoplasia-specific expression profile characterized by changes in multiple cancer-associated genes. Importantly, this neoplastic profile was evident in nonneoplastic mucosa, suggesting that the identified genes may represent markers preceding cancer. CONCLUSIONS: Gastric intraglandular neoplasia is induced in primates when H pylori infection is associated with consumption of a carcinogen similar to the nitrosaminesfound in pickled vegetables, suggesting that H pylori and the carcinogen synergistically induce gastric neoplasia in primates. Monkey arrays used for analysis of the affect of Helicobacter pylori and diet on development of gastric cancer. Each RNA was hybridized against a common reference. Biopsy numbers represent the following in terms of descriptions used in publication of the paper... Each set of numbers/descriptions is organized in the following order: Biopsy#; Monkey#; Group Code on Fig 5 Biopsy #4674; AB24; E; E1 Biopsy #4684; 16G; E; E2 Biopsy #4716; 89G; H; H1 Biopsy #4724; 54H; H; H2 Biopsy #4720; 20G; H; H3 Biopsy #4710; 92F; C; C1 Biopsy #4714; 26G; C; C2 Biopsy #4712; 92G; C; C3 Biopsy #4726; 08G; H; H4 Biopsy #4722; 57G; H; H5 Biopsy #4718; 85G; H; H6 Biopsy #4694; 48H; HE NON; HE1 Biopsy #4686; 59H; HE NON; HE2 Biopsy #4690; 81G; HE NEO; HE3 Biopsy #4696; 36G; HE NEO; HE4 Biopsy #4692; 63G; HE NEO; HE5 Biopsy #4680; 76G; E; E3 Biopsy #4682; 52G; E; E4 Biopsy #4678; 15G; E; E5 Biopsy #4676; 93G; E; E6 Biopsy #4688; 47H; HE NON; HE6 A pathogenicity experiment design type is where an infective agent such as a bacterium, virus, protozoan, fungus etc. infects a host organism(s) and the infective agent is assayed. Infection: Rhesus monkeys were infected with H. pylori (+/-) Compound Based Treatment: Rhesus monkeys were treated with ENNG (N-ethyl-N-nitrosoguanidine) (+/-)

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Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals.

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Pathways of Gastric Carcinogenesis, <i>Helicobacter pylori</i> Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals.

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