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)

Gastric cancer is poorly-responsive to widely used antitumour drugs, the efficacy of which is thought to be related to the capacity of triggering apoptosis. This process requires a series of gene products including a functional p53 protein. We tested the effects of two DNA topoisomerase II poisons, etoposide and doxorubicin, on gastric cancer cell lines with different genetic lesions. We characterised MKN74 and MKN28 cells for p53 gene status and for the expression of p53 and p21 proteins, as well as of topoisomerase II alpha and beta isoforms. After drug treatments, the cells were analysed for drug cytotoxicity, colony forming ability, cell cycle distribution and presence of apoptotic features. Our findings demonstrated that both etoposide and doxorubicin have a potent anti-proliferative effect on gastric cancer cells. Cell death kinetics was different in the two cell lines, MKN74 cells being more sensitive than MKN28 to the drugs. MKN74 cells, although harboring a wt p53 gene, were unable to undergo a massive apoptosis following etoposide treatment. The response of this cell line might be related to the topoisomerase II beta isozyme, the expression of which proved to be undetectable.
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PMID:Effects of topoisomerase II inhibitors on gastric cancer cells characterized by different genetic lesions. 1172 58

Triptolide, a major component in the extract of Chinese herbal plant Tripterygium wilfordii Hook f (TWHf), has potential anti-neoplastic effect. In the present study we investigated the potential therapeutic effects and mechanisms of triptolide against human gastric cancer cells. Four gastric cancer cell lines with different p53 status, AGS and MKN-45 (wild type p53); MKN-28 and SGC-7901 (mutant p53) were observed as to cell growth inhibition and induction of apoptosis in response to triptolide treatment. We showed that triptolide inhibited cell growth, induced apoptosis and suppressed NK-kappaB and AP-1 transactivation in AGS cells with wild-type p53. Triptolide induced apoptosis by stimulating the expressions of p53, p21(waf1/cip1), bax protein, and increased the activity of caspases. In addition, it caused cell cycle arrest in the G(0)/G(1) phase. To examine the role of p53 in these functions, we showed that suppression of p53 level with antisense oligonucleotide abrogated triptolide-induced apoptosis and over-expression of dominant negative p53 abolished the inhibitory effect on NF-kappaB activation. Furthermore, we demonstrated that triptolide had differential effects on gastric cancer cells with different p53 status. We showed that triptolide also inhibited cell growth and induced apoptosis in MKN-45 with wild-type p53, whereas it had no significant growth-inhibition and apoptosis induction effects on the MKN-28 and SGC-7901 cells with mutant p53. Our data suggest that triptolide exhibits anti-tumor and anti-inflammatory effects by inhibiting cell proliferation, inducing apoptosis and inhibiting NF-kappaB and AP-1 transcriptional activity. However, a functional p53 is required for these proapoptotic, anti-inflammatory and anti-tumor effects.
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PMID:Functional p53 is required for triptolide-induced apoptosis and AP-1 and nuclear factor-kappaB activation in gastric cancer cells. 1175 84

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

WNT signaling pathway is implicated in carcinogenesis and embryogenesis. WNT signal is transduced to the beta-catenin - TCF pathway, the JNK pathway, or the Ca2+-releasing pathway through seven-transmembrane-type WNT receptors encoded by Frizzled (FZD) genes. Xenopus Strabismus (Stbm) is a tetra-spanning transmembrane protein interacting with Dishevelled, and is a negative regulator of the WNT - beta-catenin - TCF signaling pathway. STB1/KIAA1215/VANGL2 is a human orthologue of Xenopus Stbm (90.6% total-amino-acid identity). Here, STB2/VANGL1 gene fragments were identified in human genome draft sequences by using bioinformatics, and STB2 cDNAs were isolated by using cDNA-PCR. STB2 gene consisted of at lest 7 exons, and encoded a 524-amino-acid protein with 4 transmembrane domains and the C-terminal Ser/Thr-X-Val motif. Human STB2 was homologous to human STB1 (73.1% total-amino-acid identity) and Xenopus Stbm (72.7% total-amino-acid identity). STB2 gene was clustered with Calsequestrin 2 (CASQ2) gene in tail-to-tail manner (interval less than 5.0 kb), and CASQ2 gene is mapped to human chromosome 1p11-p13.3 or linked to human chromosome 1p13-p21. STB2 mRNAs of 4.8- and 6.8-kb in size were expressed almost ubiquitously in various normal tissues. STB2 mRNA was significantly up-regulated in gastric cancer cell lines MKN28, MKN74, pancreatic cancer cell lines BxPC-3, PSN-1 and Hs766T. On the other hand, STB2 mRNA was significantly down-regulated in a pancreatic cancer cell line AsPC-1. This is the first report on molecular cloning and characterization of STB2.
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PMID:Molecular cloning and characterization of Strabismus 2 (STB2). 1195 95

Helicobacter pylori (H. pylori) infection is associated with changes in epithelial turnover, through their significance of these in gastric carcinogenesis is still controversial. The purpose of this study was to determine the influence of H. pylori infection on cell proliferation and the relation with the cell-cycle regulators, and finally to provide insights into the mechanism by which H. pylori may lead to gastric carcinogenesis. We investigated Ki-67, p53, p21(Waf1/Cip1), cyclin D1 expression in 55 patients with H. pylori gastritis, and compared the results with patients those of non-H. pylori gastritis patients (n=21), gastric adenocarcinoma patients (n=8) and samples with normal gastric mucosa (n=12). Gastric biopsies were histologically evaluated for inflammatory reaction, intestinal metaplasia and atrophy according to the Sydney system. Overexpression of Ki-67, p53, p21(Waf1/Cip1) and cyclin D1 was found in H. pylori gastritis patients (32.7%, 10.9%, 20.0% and 7.3%, respectively), whereas only scattered expression in cells in the neck region of the crypts, but no overexpression was found in gastric antral epithelial cells in biopsy specimens from patients with non-H. pylori gastritis and noninflammed mucosa. A significant relationship was found between the grade of H. pylori colonization and Ki-67, p53, p21(Waf1/Cip1) and cyclin D1 expression. Expression was significantly higher in patients with intestinal metaplasia with atrophy, whereas no overexpression was found in patients without intestinal metaplasia with atrophy (p=0.05). H. pylori infection is associated with increased cell proliferation, increased epithelial DNA damage, and atrophy, which might contribute to the development of gastric cancer. Even if the exact mechanism has not been elucidated yet, our results suggest that H. pylori infection acts as a cofactor in gastric carcinogenesis.
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PMID:Expression of cell-cycle related proteins in Helicobacter pylori gastritis and association with gastric carcinoma. 1208 13

Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of gastrointestinal cancers. Recently, a similar protective effect has been demonstrated by the specific cyclo-oxygenase-2 (COX-2) inhibitors. However, the exact mechanism that accounts for the anti-proliferative effect of specific COX-2 inhibitors is still not fully understood, and it is still controversial whether these protective effects are predominantly mediated through the inhibition of COX-2 activity and prostaglandin synthesis. Identification of molecular targets regulated by COX-2 inhibitors could lead to a better understanding of their pro-apoptotic and anti-neoplastic activities. In the present study, we investigated the effect and the possible molecular target of a COX-2-specific inhibitor SC-236 on gastric cancer. We showed that SC-236 induced apoptosis in gastric cancer cells. However, this effect was not dependent on COX-2 inhibition. SC-236 down-regulated the protein expression and kinase activity of PKC-beta(1), increased the expression of PKCdelta and PKCeta, but did not alter the expression of other PKC isoforms in AGS cells. Moreover, exogenous prostaglandins or PGE(2) receptor antagonists could not reverse the inhibition effect on PKCbeta(1) by SC-236, which suggested that this effect occurred through a mechanism independent of cyclo-oxygenase activity and prostaglandin synthesis. Overexpression of PKCbeta(1) attenuated the apoptotic response of AGS cells to SC-236 and was associated with overexpression of p21(waf1/cip1). Inhibition of PKCbeta(1)-mediated overexpression of p21(waf1/cip1) partially reduced the anti-apoptotic effect of PKCbeta(1). The down-regulation of PKCbeta(1) provides an explanation for COX-independent apoptotic effects of specific COX-2 inhibitor in cultured gastric cancer cells. We also suggest that PKCbeta(1) act as survival mediator in gastric cancer, and its down-regulation by COX-2 inhibitor SC-236 may provide new target for future treatment of gastric cancer.
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PMID:Novel target for induction of apoptosis by cyclo-oxygenase-2 inhibitor SC-236 through a protein kinase C-beta(1)-dependent pathway. 1220 23

Helicobacter pylori, the main cause of chronic gastritis, plays a central role in the etiology of peptic ulcer disease and gastric cancer. In vitro studies have shown that H. pylori increases gastric epithelial cell turnover, thus increasing the risk for the development of neoplastic clones. The mechanisms by which H. pylori promotes perturbation of cell proliferation are not yet elucidated. To investigate whether products released by H. pylori in culture media interfere with cell cycle progression of human gastric epithelial cells, four cell lines (MKN 28, MKN 7, MKN 74, and AGS) were incubated in the presence of H. pylori broth culture filtrate. Cell cycle analysis showed that a H. pylori-released factor(s) significantly inhibited the G1- to S-phase progression of MKN 28 and MKN 7 cell lines, with a reversible, nonlethal mechanism, independent of the expression of VacA, CagA, and/or urease. The cell cycle inhibition occurred concomitantly with an increase in p27(KIP1) protein levels, a reduction in Rb protein phosphorylation on serine residues 807-811, and a significant decrease in cyclin E-associated cdk2 activity. In contrast, the cell cycle progression of MKN 74 and AGS cell lines was not affected by the H. pylori-released factor(s). In normal human fibroblasts, G1-phase cell accumulation was concomitant with the reduction in Rb protein phosphorylation; that, however, appeared to be dependent on p21(WAF1/CIP1) rather than on p27(KIP1) protein. A preliminary characterization showed that the molecular mass of the partially purified cell cycle inhibitory factor(s) was approximately 40 kDa. These results suggest that H. pylori releases a soluble factor(s) that may affect cell cycle progression of gastric epithelial cells through elevated levels of cdk inhibitor p27(KIP1). This factor(s) might act in vivo on noncolonized distant cells, the most proliferating cells of human gastric mucosa.
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PMID:Helicobacter pylori releases a factor(s) inhibiting cell cycle progression of human gastric cell lines by affecting cyclin E/cdk2 kinase activity and Rb protein phosphorylation through enhanced p27(KIP1) protein expression. 1244 Nov 36

Esophageal cancer is still one of the most widespread diseases, and surgery for esophageal carcinoma is very stressful for patients. Even though lymph node metastasis occurs more frequently in cases of early esophageal cancer than it does in cases of gastric cancer, surgeons prefer to avoid lymph node dissection if possible, thereby subjecting patients to less invasion. Thus, the aim of the present study was to examine the possibility of predicting lymph node metastasis on the basis of tumor location, quantification theory II analysis of tumor expression of genetic markers in primary esophageal cancer. Surgical specimens from 63 patients of esophageal cancer with submucosal invasion were examined for the relationship between tumor location and lymph node metastasis. In 19 of these 63 patients, p53, p21(Waf1, and proliferating cell nuclear antigen (PCNA) were examined immunohistologically, and to quantify the risk of lymph node metastasis, computer analysis was performed on the basis of quantification theory II, in which pathological lymph node metastasis (pN) was the objective variable and "high" or "low" expression of each of the three markers was the predictive variable. Tumors located in the lower third of the esophagus had no lymph node metastasis to the upper mediastinal region, and were thus indicated for trans-hiatal esophagectomy. A coefficient greater than 0.91 predicted node negative disease accurately without false-negative results; false-positive results were obtained for 54.5% of patients with a coefficient less than 0.064. Thus, we found that quantification theory II may be useful when considering indications for surgery without lymph node dissection in some cases of T1 esophageal carcinoma.
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PMID:Prediction of lymph node metastasis by p53, p21(Waf1), and PCNA expression in esophageal cancer patients. 1286 74

H. pylori infection of the gastric mucosa is associated with increased epithelial cell apoptosis. In vitro, interferon-gamma and TNF-alpha have been shown to increase the sensitivity of cells to apoptosis induced by H. pylori. The p53 tumor suppressor gene is frequently mutated in many cancers, including gastric cancer. Since p53 protein can induce apoptosis, we sought to determine whether or not p53 increases the ability of gastric epithelial cells to undergo apoptosis in response to H. pylori-induced cell injury. Human gastric epithelial cell lines, AGS (p53 wild-type) cells and AGS cells infected with HPV E6 gene (AGS-E6) to inactivate p53 were exposed to H. pylori. The p53, p21, and p14ARF proteins were measured in gastric epithelial cells by immunoelectrophoresis. Gastric epithelial cell apoptosis was measured by DNA end-labeling assay (TUNEL) and subG0 cell fractions using flow cytometry, and by agarose gel electrophoresis of DNA. Exposure to H. pylori increased the levels of p53, p21, and p14ARF proteins two fold in AGS cells. Gastric AGS cells with fragmented DNA increased from 1.1% to 68% in after exposure to H. pylori for 24 hr. However, AGS-E6 cells were relatively resistant to apoptosis induced by H. pylori (only 15% of cells underwent apoptosis). In additional experiments, mouse embryonic fibroblasts (MEFs) were used to further investigate the role of ARF in stabilizing p53 after exposure to H. pylori. Wild-type and p19ARF-/- MEFs were exposed to H. pylori and evaluated for activation of p53, p19ARF, and apoptosis. As with AGS cells, H. pylori stimulated a 2-fold increase in p53 and p19ARF in wild-type MEFs; however, there was no increase in p53 in ARF-null MEFs. H. pylori easily stimulated apoptosis in wild-type MEFs, although, the absence of p19ARF significantly reduced the ability of H. pylori to induce apoptosis in these cells. Activation of ARF by H. pylori is important in stabilizing p53 resulting in increased apoptosis. Thus, inactivation of either ARF or p53 in gastric cells may reduce their ability to undergo apoptosis in response to injury induced by H. pylori.
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PMID:p53 and p14 increase sensitivity of gastric cells to H. pylori-induced apoptosis. 1287 Jul 84

The aim of the present study was to examine the significance of the p21 expression in gastric cancer. We examined the expression of p53, p21, TGF beta 1 and PCNA in 75 cases of gastric cancer using immunohistochemical examinations and the expression of p21 RNA by in situ hybridization (ISH). The combination of p53 and p21 expression was related to depth of invasion, lymph node metastasis, and stage grouping. The survival curves of the p53 negative-Group and the p21-positive Group were significantly higher than those of the p53-positive and the p21-negative Group, the p53-and-p21-both-positive Group, and the p53-and-p21-both-negative Group (each p < 0.01). The average PCNA Labelling Index (LI) of the p53-negative-and-p21-positive Group was significantly lower than that of either the p53-positive-and-p21-negative Group or the p53-and-p21-both-positive Group or the p53-and-p21-both-negative Group (p < 0.01, p < 0.05, p < 0.05, respectively). All of the p53-and-p21-both-positive cases were TGF beta 1 positive, and the rate of the TGF beta 1 positive cases in the p53-and-p21-both-positive Group was significantly higher than that of the p53-positive-and-p21-negative Group, and than the rate in the p53-and-p21-both-negative Group (each p < 0.01). The survival curves of the cases with expression of p21 RNA were higher than that of cases without p21 RNA (p < 0.05). Many of the p53-positive-and-p21-negative cases were advanced cancer with very poor prognosis, but many of the p53-negative-and-p21-positive cases were early cancer with good prognosis. These results suggest that p21 suppressed synthesis of DNA via PCNA, and TGF beta 1 is a regulation factor for the expression of p21, and that the combination of p53 and p21 expression is concluded to be a useful prognostic marker of gastric carcinoma.
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PMID:The expression of p53, p21 and TGF beta 1 in gastric carcinoma. 1297 Dec 56


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