Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although in vitro studies have suggested that Helicobacter pylori not only attaches to cultured cells but also induces signal transduction events in host cells, the underlying mechanism of H. pylori action has yet to be fully investigated. In the present study, a cytotoxin-positive H. pylori was used to infect and examined for its effect on the stimulation of second messengers in human gastric adenocarcinoma (AGS). Results showed that H. pylori increased cytosolic free calcium concentration [Ca2+]i in host cells in a dose-dependent manner. The increase of [Ca2+]i was due to release from the intracellular Ca2+ store as well as entry to the extracellular Ca2+. H. pylori infection on host cells was also found to induce the generations of inositol phosphates, adenosine 3', 5'-cyclic monophosphate, and guanosine 3',5'-cyclic monophosphate, and to stimulate the secretion of pepsinogen.
Int J Mol Med 1999 Apr
PMID:Signaling pathway and pepsinogen secretion in Helicobacter pylori-infected human gastric adenocarcinoma. 1008 17

For tumor progression, a cascade of linked sequential biological events is essential. We tried to test whether biological therapy can modulate specific biological phenotypes and increase the anti-tumor effect when combined with chemotherapy. Five human gastric cancer cell lines (YCC-1, YCC-2, YCC-3, YCC-7, AGS) were used in these studies. Pentosan polysulfate (PPS) as a heparin-binding growth factor inhibitor, Tranexamic acid as a plasmin inhibitor, Lovastatin as an adhesion inhibitor and Adriamycin as a chemotherapeutic agent were selected. The effects of each drug on colony formation and tumor cell proliferation were evaluated by soft agar assay and cell proliferation assay, respectively to test direct anti-tumor effect. The expression of uPA, PAI-1 was determined by ELISA, while MMPs activity was evaluated by zymography. PPS suppressed the colony-forming activity as much as Adriamycin did, but it showed only cytostatic effects in cell proliferation assay. Migration capacity using Boyden chamber assay was more closely correlated with adhesive capacity than uPA or MMP-2 expression. The motility inhibitory effect of Tranexamic acid was observed in the YCC-7 cell line, which expressed all the required biological phenotypes for migration. In AGS, with high cell motility and adhesiveness, the adhesion was inhibited by Lovastatin and most of the inhibitory effect was recovered by Mevalonate. When PPS was combined with Adriamycin on the Adriamycin-resistant, midkine (MK) gene expressing YCC-7 cell line, the growth inhibition rate increased up to 84%, while that for a single treatment of PPS or Adriamycin was 40% and 22%, respectively (p=0.001). When we combined Tranexamic acid and Adriamycin, we observed the synergistic effect in YCC-3 and YCC-7, while no combined effect was found in YCC-1. The combination of Lovastatin and Adriamycin did not show any combined effects in any of the cell lines. In conclusion, a synergistic anti-proliferative effect (chemo-sensitization) with combined chemo-biotherapy was found in cancer cells with specific biological target, MK. The anti-motility effect was the greatest when the gastric cancer cells expressed all the specific biological phenotypes.
Int J Mol Med 1999 Aug
PMID:Modulation of biological phenotypes for tumor growth and metastasis by target-specific biological inhibitors in gastric cancer. 1040 90

The proximal region of the human gastrin gene promoter contains three GC/GT boxes at positions -140 to -134 bp, -108 to -102 bp and -67 to -61 bp. In this study we have examined the significance of the three elements, and their role in Sp1 and Sp3 mediated gastrin transcription. In AGS cells, mutation of each of the boxes caused a moderate decrease in promoter activity from 33 to 63%, whereas double or triple mutations reduced activity to 3-12%. In Drosophila cells Sp1 activated the promoter, mainly through the distal GC box. Similarly, co-transfection of heterologous promoter constructs revealed that only the distal GC box increased activation by Sp1. The effect of Sp3 was cell-line dependent, since Sp3 inhibited the gastrin promoter activity in AGS cells and caused a synergistic activation of the Sp1 stimulated gastrin promoter in Drosophila cells. Both effects were dependent on the C-terminal DNA binding domain of Sp3. The results indicates that the combined effect of the GC/GT boxes and the ratio between Sp1 and Sp3 are important for gastrin gene expression.
Mol Cell Endocrinol 1999 Sep 10
PMID:Composite action of three GC/GT boxes in the proximal promoter region is important for gastrin gene transcription. 1058 Aug 33

E2F -1 is a transcription factor that regulates cell cycle progression into S-phase. Deregulation of E2F-1 activity has been associated with cellular commitment to apoptosis. Also critical in the regulation of S-phase are the actions of the cyclin dependent kinases, Cdk2 and cdc2. Inhibition of these cyclin dependent kinases has been similarly associated with disrupting orderly S-phase progression and causing subsequent apoptosis in certain cancer cells. In this study, we examine the ability of adenovirus-mediated E2F-1 overexpression to induce apoptosis in human gastric carcinoma cells. Furthermore, we investigate the effect of the cyclin dependent kinase inhibitors, olomoucine and roscovitine, on E2F-1-mediated apoptosis in human gastric carcinoma cells. AGS and SNU-1 gastric adenocarcinoma cells were infected with adenoviral vectors expressing E2F-1 (Ad5CMVE2F-1) or control viruses expressing beta-galactosidase (Ad5CMVLacZ) or lacking a transgene (Ad5). Gastric adenocarcinoma cells were then independently treated with roscovitine or olomoucine. Finally, gastric adenocarcinoma cells were infected with the various adenoviral vectors in combination with roscovitine or olomoucine. E2F-1 overexpression resulted in an 85% reduction in cell viability at 72 h compared to controls. Combining E2F-1 overexpression with roscovitine resulted in >99% reduction in cell viability by 72 h. Overexpression of E2F-1 resulted in premature S-phase entry and G2/M arrest at 24 h, followed by apoptosis by 72 h. Combining E2F-1 overexpression with roscovitine resulted in an earlier G2/M arrest, followed by a more complete, widespread apoptotic response by 24 h. Caspase 3/CPP32 activation and PARP cleavage in response to E2F-1 overexpression, alone and in combination with roscovitine, implicate the caspase cascade in E2F-1-mediated apoptosis of gastric cancer cells. Bax levels also increased in response to E2F-1 gene transfer, alone and in combination with roscovitine. E2F-1 overexpression induces widespread apoptosis in human gastric carcinoma cells. Combining E2F-1 overexpression with cyclin-dependent kinase inhibitors results in an enhanced apoptotic response, causing nearly complete gastric tumor cell death within 72 h. E2F-1 gene therapy in combination with cyclin dependent kinase inhibitors is a potentially active chemogene therapy strategy for the treatment of human gastric cancer.
Int J Mol Med 2000 Jul
PMID:Adenovirus-mediated E2F-1 gene transfer induces an apoptotic response in human gastric carcinoma cells that is enhanced by cyclin dependent kinase inhibitors. 1085 Dec 67

Helicobacter pylori colonizes the human stomach and is the causative agent of a variety of gastric diseases. After bacterial attachment, the H. pylori CagA protein is translocated into gastric epithelial cells and tyrosine phosphorylated. This process is associated with characteristic cytoskeletal rearrangements, resulting in a scatter factor-like ('hummingbird') phenotype. In this study, using a cagA mutant complemented with wild-type cagA and transiently expressing CagA in AGS cells, we have demonstrated that translocated CagA is necessary for rearrangements of the actin cytoskeleton to occur. Anti-phosphotyrosine immunoblotting studies and treatment of infected cells with phosphotyrosine kinase inhibitors suggested that not only translocation but also phosphorylation of CagA is important in this process. Transient expression of CagA-green fluorescent protein (GFP) fusion proteins and two-dimensional gel electrophoresis of CagA protein species demonstrated tyrosine phosphorylation in the C-terminus. Site-directed mutagenesis of CagA revealed that tyrosine residue 972 is essential for induction of the cellular phenotype. We have also demonstrated that translocation and phosphorylation of CagA is necessary but not sufficient for induction of the hummingbird phenotype in AGS cells, indicating the involvement of as yet unidentified bacterial factor(s).
Mol Microbiol 2001 Nov
PMID:Phosphorylation of tyrosine 972 of the Helicobacter pylori CagA protein is essential for induction of a scattering phenotype in gastric epithelial cells. 1172 31

Helicobacter pylori infection induces apoptosis in gastric epithelial cells. Here, we report a novel apoptosis-inducing protein that functions as a leading factor in H. pylori-mediated apoptosis induction. We purified the protein from H. pylori by separating fractions that showed apoptosis-inducing activity. This protein induced apoptosis of AGS cells in a dose-dependent manner. The purified protein consisted of two protein fragments with molecular masses of about 40 and 22 kDa, which combined to constitute a single complex in their natural form. N-terminal sequencing indicated that both these protein fragments were encoded by the HP1118 gene. The purified protein exhibited gamma-glutamyl transpeptidase activity, the inhibition of which by 6-diazo-5-oxo-l-norleucine resulted in a complete loss of apoptosis-inducing activity. To the best of our knowledge, the apoptosis-inducing function is a newly identified physiological role for bacterial gamma-glutamyl transpeptidase. The apoptosis-inducing activity of the isogenic mutant gamma-glutamyl transpeptidase-deficient strain was significantly lower compared with that of the parent strain, demonstrating that gamma-glutamyl transpeptidase plays a significant role in H. pylori-mediated apoptosis. Our findings provide new insights into H. pylori pathogenicity and reveal a novel aspect of the bacterial gamma-glutamyl transpeptidase function.
Mol Microbiol 2003 Jan
PMID:A novel apoptosis-inducing protein from Helicobacter pylori. 1251 94

Camptothecin, a topoisomerase I inhibitor, is a well-known anticancer drug. However, its mechanism has not been well studied in human gastric cancer cell lines. Camptothecin induced apoptotic cell death in human gastric cancer cell line AGS. Z-VAD-fmk, pan-caspase inhibitor, blocked apoptotic phenotypes induced by camptothecin suggesting that caspases are involved in camptothecin-induced cell death. An inhibitor of caspase-6 or -8 or -9 did not prevent cell death by camptothecin. Various protease inhibitors failed to prevent camptothecin-induced cell death. These results suggest that only few caspases are involved in camptothecin-induced cell death. Camptothecin induced phosphorylation of ERK1/2, JNK, and p38 MAPK, in a dose and time-dependent manner in AGS. Z-VAD-fmk did not affect MAPK signaling induced by camptothecin suggesting that caspase signaling occurs downstream of MAPK signaling. Blocking of p38 MAPK, but not ERK1/2, resulted in partial inhibition of cell death and PARP cleavage by camptothecin in AGS. Taken together, MAPK signaling is associated with apoptotic cell death by camptothecin.
Mol Cells 2002 Dec 31
PMID:MAPK signaling is involved in camptothecin-induced cell death. 1252 Dec 96

Cyclopentenone prostaglandins (CyPGs), derivatives of arachidonic acid, have been suggested to exert growth-inhibitory activity through peroxisome proliferator-activated receptor (PPAR)-dependent and -independent mechanisms. Here we examined various eicosanoids for growth inhibition and found that the terminal derivative of prostaglandin (PG) J(2) metabolism, 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)), and PGA(1) markedly inhibited the growth and induced apoptosis in AGS gastric carcinoma cells. There were no significant increases in cell death and DNA-fragmentation in the cells with overexpression of PPARalpha or PPARgamma, indicating the possibility that 15d-PGJ(2) and PGA(1) induced apoptosis through PPAR-independent pathway. Moreover, 15d-PGJ(2) and PGA(1) activated the c-jun N-terminal kinase (JNK) and caspase-3 activity in dose- and time-dependent manners. To examine further the role of JNK signaling cascades in apoptosis induced by 15d-PGJ(2) and PGA(1), we transfected dominant-negative (DN) mutants of JNK plasmid into the cells to analyze the apoptotic characteristics of cells overexpressing DN-JNK following exposure to 15d-PGJ(2) and PGA(1). Overexpression of DN-JNK significantly repressed both endogenous JNK and caspase-3 activity, and subsequently decreased apoptosis induced by 15d-PGJ(2) and PGA(1). These results suggested that CyPGs, such as 15d-PGJ(2) and PGA(1), activated JNK signaling pathway, and that JNK activation may be involved in 15d-PGJ(2)- and PGA(1)-induced apoptosis.
Mol Carcinog 2003 May
PMID:Involvement of c-jun N-terminal kinase activation in 15-deoxy-delta12,14-prostaglandin J2-and prostaglandin A1-induced apoptosis in AGS gastric epithelial cells. 1272 Feb 96

Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of paracoccidioidomycosis (PCM), the most prevalent systemic mycosis in Latin America. Pathogenicity appears to be intimately related to the dimorphic transition from the hyphal to the yeast form, which is induced by a shift from environmental temperature to the temperature of the mammalian host. Little information is available on the P. brasiliensis genes that are necessary during the pathogenic phase. We have therefore undertaken Suppression Subtraction Hybridization (SSH) and macroarray analyses with the aim of identifying genes that are preferentially expressed in the yeast phase. Genes identified by both procedures as being more highly expressed in the yeast phase are involved in basic metabolism, signal transduction, growth and morphogenesis, and sulfur metabolism. In order to test whether the observed changes in gene expression reflect the differences between the growth conditions used to obtain the two morphological forms rather than differences intrinsic to the cell types, we performed real-time RT-PCR experiments using RNAs derived from both yeast cells and mycelia that had been cultured at 37 degrees C and 26 degrees C in either complete medium (YPD or Sabouraud) or minimal medium. Twenty genes, including AGS1 (alpha-1,3-glucan synthase) and TSA1 (thiol-specific antioxidant), were shown to be more highly expressed in the yeast cells than in the hyphae. Although their levels of expression could be different in rich and minimal media, there was a general tendency for these genes to be more highly expressed in the yeast cells.
Mol Genet Genomics 2004 Jul
PMID:Identification of genes preferentially expressed in the pathogenic yeast phase of Paracoccidioides brasiliensis, using suppression subtraction hybridization and differential macroarray analysis. 1513 90

Histoplasma capsulatum is a fungal pathogen that causes respiratory and systemic disease by proliferating within macrophages. While much is known about histoplasmosis, only a single virulence factor has been defined, in part because of the inefficiency of Histoplasma reverse genetics. As an alternative to allelic replacement, we have developed a telomeric plasmid-based system for silencing gene expression in Histoplasma by RNA interference (RNAi). Episomal expression of long RNAs that form stem-loop structures triggered gene silencing. To test the effectiveness of RNAi in Histoplasma, we depleted expression of a gfp transgene as well as two endogenous genes, ADE2 and URA5, and showed significant reductions in corresponding gene function. Silencing was target gene specific, stable during macrophage infection and reversible. We used RNAi targeting AGS1 (encoding alpha-(1,3)-glucan synthase) to deplete levels of alpha-(1,3)-glucan, a cell wall polysaccharide. Loss of alpha-(1,3)-glucan by RNAi yielded phenotypes indistinguishable from an AGS1 deletion: attenuation of the ability to kill macrophages and colonize murine lungs. This demonstrates for the first time that alpha-(1,3)-glucan is an important contributor to Histoplasma virulence.
Mol Microbiol 2004 Jul
PMID:RNA interference in Histoplasma capsulatum demonstrates a role for alpha-(1,3)-glucan in virulence. 1522 11


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