Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Helicobacter pylori causes peptic ulceration and gastric adenocarcinoma; the latter is common in Iran but not in Iraq. We hypothesized that more virulent H. pylori strains may be found in Iran than in Iraq and so compared established and newly described virulence factors in strains from these countries. We studied 59 unselected dyspeptic patients from Iran and 49 from Iraq. cagA was found in similar proportions of strains from both countries (76% in Iran versus 71% in Iraq) and was significantly associated with peptic ulcer disease in Iraq (P <or= 0.01) but not in Iran. cagA alleles encoding four or more tyrosine phosphorylation motifs were found in 12% of the Iranian strains but none of the Iraqi strains (P = 0.02). There were no significant differences in the vacA signal-, middle-, or intermediate-region types between Iranian and Iraqi strains. Among the strains from Iran, vacA genotypes showed no specific peptic ulcer associations, but among the strains from Iraq, vacA i1 strains were associated with gastric ulcer (P <or= 0.02), mimicking their previously demonstrated association with gastric cancer in Iran. dupA was found in similar proportions of Iranian and Iraqi strains (38% and 32%, respectively) and was associated with peptic ulceration in Iraqi patients (P <or= 0.01) but not Iranian patients. H. pylori strains from Iraq and Iran possess virulence factors similar to those in Western countries. The presence of cagA with more phosphorylation motifs in Iranian strains may contribute to the higher incidence of gastric cancer. However, the association between strain virulence markers and disease in Iraq but not Iran suggests that other host and environmental factors may be more important in the disease-prone Iranian population.
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PMID:Differences in virulence markers between Helicobacter pylori strains from Iraq and those from Iran: potential importance of regional differences in H. pylori-associated disease. 1835 34

This article discusses recent advances in gastric cancer research that have improved treatment and outcomes of gastric malignancy, or have the potential to do so. The significance of Helicobacter pylori infection and eradication, immunology, host genetics, proto-oncogenes, and epigenetic alterations in gastric cancer are discussed. Abnormal signaling through growth factor pathways (tyrosine kinases and gastrointestinal peptides) presents ample opportunities for therapeutic intervention that are currently being tested in clinical trials. Drugs targeting abnormal epigenetic changes, such as DNA hypermethylation and histone deacetylation, are also on the horizon, although most of this research is still in the preclinical phase. The potential prognostic implications of genetics and immunology in gastric cancer prognosis are also reviewed.
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PMID:Translational research in gastric malignancy. 1837 55

We have identified a critical role for amplified FGFR2 in gastric cancer cell proliferation and survival. In a panel of gastric cancer cell lines, fibroblast growth factor receptor 2 (FGFR2) was overexpressed and tyrosine phosphorylated selectively in FGFR2-amplified cell lines KatoIII, Snu16, and OCUM-2M. FGFR2 kinase inhibition by a specific small-molecule inhibitor resulted in selective and potent growth inhibition in FGFR2-amplified cell lines, resulting in growth arrest in KatoIII cells and prominent induction of apoptosis in both Snu16 and OCUM-2M cells. FGFR2-amplified cell lines also contained elevated phosphotyrosine in EGFR, Her2, and Erbb3, but the elevated phosphorylation in EGFR could not be inhibited by gefitinib or erlotinib. We show that the elevated EGFR, Her2, and Erbb3 phosphotyrosine is dependent on FGFR2, revealing EGFR family kinases to be downstream targets of amplified FGFR2. Moreover, shRNA to Erbb3 resulted in a loss of proliferation, confirming a functional role for the activated EGFR signaling pathway. These results reveal that both the FGFR2 and EGFR family signaling pathways are activated in FGFR2-amplified gastric cancer cell lines to drive cell proliferation and survival. Inhibitors of FGFR2 or Erbb3 signaling may have therapeutic efficacy in the subset of gastric cancers containing FGFR2 amplification.
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PMID:FGFR2-amplified gastric cancer cell lines require FGFR2 and Erbb3 signaling for growth and survival. 1838 41

Cortactin is frequently overexpressed in cancer cells, and changes of the levels of its tyrosine phosphorylation have been observed in several cancer cells. However, how the expression level and phosphorylation state of cortactin would influence the ultimate cellular function of cancer cells is unknown. In this study, we analyzed the role of cortactin in gastric and breast cancer cell lines using RNA interference technique and found that knockdown of cortactin inhibited cell migration in a subset of gastric cancer cells with a lower level of its tyrosine phosphorylation, whereas it greatly enhanced cell migration and increased tyrosine phosphorylation of p130Cas in other subsets of cells with hyperphosphorylated cortactin. Consistent results were obtained when hyperphosphorylation of cortactin was induced in MCF7 breast cancer cells by expressing Fyn tyrosine kinase. Additionally, immunostaining analysis showed that knockdown of hyperphosphorylated cortactin resulted in the recruitment of p130Cas to focal adhesions. These results suggest that cortactin hyperphosphorylation suppresses cell migration possibly through the inhibition of membrane localization and tyrosine phosphorylation of p130Cas.
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PMID:Hyperphosphorylated cortactin in cancer cells plays an inhibitory role in cell motility. 1840 44

Infection with Helicobacter pylori cagA-positive strains is associated with gastritis, ulcerations, and gastric cancer. CagA is translocated into infected epithelial cells by a type IV secretion system and can be tyrosine phosphorylated, inducing signal transduction and motogenic responses in epithelial cells. Cellular cholesterol, a vital component of the membrane, contributes to membrane dynamics and functions and is important in VacA intoxication and phagocyte evasion during H. pylori infection. In this investigation, we showed that cholesterol extraction by methyl-beta-cyclodextrin reduced the level of CagA translocation and phosphorylation. Confocal microscope visualization revealed that a significant portion of translocated CagA was colocalized with the raft marker GM1 and c-Src during infection. Moreover, GM1 was rapidly recruited into sites of bacterial attachment by live-cell imaging analysis. CagA and VacA were cofractionated with detergent-resistant membranes (DRMs), suggesting that the distribution of CagA and VacA is associated with rafts in infected cells. Upon cholesterol depletion, the distribution shifted to non-DRMs. Accordingly, the CagA-induced hummingbird phenotype and interleukin-8 induction were blocked by cholesterol depletion. Raft-disrupting agents did not influence bacterial adherence but did significantly reduce internalization activity in AGS cells. Together, these results suggest that delivery of CagA into epithelial cells by the bacterial type IV secretion system is mediated in a cholesterol-dependent manner.
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PMID:Cholesterol depletion reduces Helicobacter pylori CagA translocation and CagA-induced responses in AGS cells. 1844 91

The signalling pathways leading to the development of Helicobacter pylori-induced gastric cancer remain poorly understood. We tested the hypothesis that H. pylori infections involve the activation of Akt signalling in human gastric epithelial cancer cells. Immunoblot, immunofluorescence and kinase assays show that H. pylori infection of gastric epithelial cells induced phosphorylation of Akt at Ser 473 and Thr 308. Mutations in the H. pylori virulence factor OipA dramatically reduced phosphorylation of Ser 473, while the cag pathogenicity island mutants predominantly inhibited phosphorylation of Thr 308. As the downstream of Akt activation, H. pylori infection inactivated the inactivation of glycogen synthase kinase 3beta at Ser 9 by its phosphorylation. As the upstream of Akt activation, H. pylori infection activated epidermal growth factor receptor (EGFR) at Tyr 992, phosphatidylinositol 3-OH kinase (PI3K) p85 subunit and PI3K-dependent kinase 1 at Ser 241. Pharmacologic inhibitors of PI3K or mitogen-activated protein kinase kinase (MEK), Akt knock-down and EGFR knock-down showed that H. pylori infection induced the activation of EGFR-->PI3K-->PI3K-dependent kinase 1-->Akt-->extracellular signal-regulated kinase signalling pathways, the inactivation of glycogen synthase kinase 3beta and interleukin-8 production. The combined functions of cag pathogenicity island and OipA were necessary and sufficient for full activation of signalling at each level. We propose activation of these pathways as a novel mechanism for H. pylori-mediated carcinogenesis.
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PMID:Helicobacter pylori activate epidermal growth factor receptor- and phosphatidylinositol 3-OH kinase-dependent Akt and glycogen synthase kinase 3beta phosphorylation. 1878 53

The pathophysiology of Helicobacter pylori-associated gastroduodenal diseases, ulcerogenesis, and carcinogenesis is intimately linked to activation of epidermal growth factor receptor (EGFR) and production of vascular endothelial growth factor (VEGF). Extracellular virulence factors, such as CagA and VacA, have been proposed to regulate EGFR activation and VEGF production in gastric epithelial cells. We demonstrate that the H. pylori secretory protein, HP0175, by virtue of its ability to bind TLR4, transactivates EGFR and stimulates EGFR-dependent VEGF production in the gastric cancer cell line AGS. Knock-out of the hp0175 gene attenuates the ability of the resultant H. pylori strain to activate EGFR or to induce VEGF production. HP0175-induced activation of EGFR is preceded by translocation of TLR4 into lipid rafts. In lipid rafts, the Src kinase family member Lyn interacts with TLR4, leading to tyrosine phosphorylation of TLR4. Knockdown of Lyn prevents HP0175-induced activation of EGFR and VEGF production. Tyrosine-phosphorylated TLR4 interacts with EGFR. This interaction is necessary for the activation of EGFR. Disruption of lipid rafts with methyl beta-cyclodextrin prevents HP0175-induced tyrosine phosphorylation of TLR4 and activation of EGFR. This mechanism of transactivation of EGFR is novel and distinct from that of metalloprotease-dependent shedding of EGF-like ligands, leading to autocrine activation of EGFR. It provides new insight into our understanding of the receptor cross-talk network.
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PMID:Helicobacter pylori protein HP0175 transactivates epidermal growth factor receptor through TLR4 in gastric epithelial cells. 1880 58

We have previously shown that Fhit tumor suppressor protein interacts with Hsp60 chaperone machinery and ferredoxin reductase (Fdxr) protein. Fhit-effector interactions are associated with a Fhit-dependent increase in Fdxr stability, followed by generation of reactive oxygen species and apoptosis induction under conditions of oxidative stress. To define Fhit structural features that affect interactions, downstream signaling, and biological outcomes, we used cancer cells expressing Fhit mutants with amino acid substitutions that alter enzymatic activity, enzyme substrate binding, or phosphorylation at tyrosine 114. Gastric cancer cell clones stably expressing mutants that do not bind substrate or cannot be phosphorylated showed decreased binding to Hsp60 and Fdxr and reduced mitochondrial localization. Expression of Fhit or mutants that bind interactor proteins results in oxidative damage and accumulation of cells in G(2)/M or sub-G(1) fractions after peroxide treatment; noninteracting mutants are defective in these biological effects. Gastric cancer clones expressing noncomplexing Fhit mutants show reduction of Fhit tumor suppressor activity, confirming that substrate binding, interaction with heat shock proteins, mitochondrial localization, and interaction with Fdxr are important for Fhit tumor suppressor function.
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PMID:Correlation of fragile histidine triad (Fhit) protein structural features with effector interactions and biological functions. 1900 24

Channels formed by the canonical transient receptor potential (TRPC) subfamily of proteins are Ca(2+)-permeable, nonselective cation channels with various functions. Through a phospholipase C (PLC)-dependent mechanism TRPC6, a member of TRPC subfamily, can be activated by receptor tyrosine kinases (RTK) or G protein-coupled receptors (GPCR), which are implicated in cell proliferation and human malignancies. Here, we report that TRPC6 has a critical role in human gastric cancer development. Expression of TRPC6 was greatly upregulated in human gastric cancer epithelial cells compared with that in normal gastric epithelial cells. Treatment of AGS or MKN45 cells, human gastric cancer cell lines, with SKF96365, an agent known to inhibit TRPC channels, arrested cell cycle in G2/M phase and suppressed cell growth. Importantly, expressing a dominant negative mutant of TRPC6 (DNC6) in these cells also arrested cell cycle in G2/M phase and inhibited cell growth. The Ca(2+) elevation in the MKN45 cells evoked by histamine was inhibited by SKF96365 and DNC6. Moreover, inhibition of TRPC6 suppressed the formation of gastric tumors in nude mice. These results suggest that Ca(2+) elevation regulated by TRPC6 channels is essential for G2/M phase transition and for the development of gastric cancers.
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PMID:Blockade of TRPC6 channels induced G2/M phase arrest and suppressed growth in human gastric cancer cells. 1961 66

Interaction of the Eph family of receptor protein tyrosine kinases and their ligands, ephrin family members, induces bidirectional signaling through cell-cell contacts. High expression of B-type ephrin is associated with high invasion potential of tumors, and we previously observed that signaling through the C-terminus of ephrin-B1 mediates the migration and invasion of cells, and is involved in the promotion of carcinomatous peritonitis in vivo. Here we show that the intracellular introduction of a synthetic peptide derived from ephrin-B1 C-terminus blocks ephrin-B1 mediated signaling in scirrhous gastric cancer cells. Treatment of cancer cells with a fusion peptide consisting of HIV-TAT and amino acids 331-346 of ephrin-B1 (PTD-EFNB1-C) suppressed the activation of RhoA, mediated by the association of ephrin-B1 with an adaptor protein Dishevelled, and also inhibited extracellular secretion of metalloproteinase. Moreover, injection of PTD-EFNB1-C peptide into the peritoneal cavity of nude mice suppressed carcinomatous peritonitis of intraperitoneally transplanted scirrhous gastric cancer cells. These results indicate the possible application of ephrin-B1 C-terminal peptide to develop novel protein therapy for scirrhous gastric carcinoma, especially in the stage of tumor progression, including peritoneal dissemination.
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PMID:Suppression of gastric cancer dissemination by ephrin-B1-derived peptide. 1980 21


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