Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, the roles of Sp1/Sp3 transcription factors in the regulation of the activity of human telomerase reverse transcriptase (hTERT) promoter in response to ceramide were examined in the A549 human lung adenocarcinoma cells. The activity of the N-terminal truncated hTERT promoter, lacking the c-Myc recognition (E-box) region but containing multiple Sp1/Sp3 sites, was also significantly inhibited by C6-ceramide, indicating a role for ceramide in the regulation of Sp1/Sp3 function. Partial inhibition of Sp1 expression using small interfering RNA resulted in a significant inhibition of the hTERT promoter. Treatment with C6-ceramide inhibited the trans-activation function of overexpressed Sp1, whereas it induced the repressor effects of exogenous Sp3 on the hTERT promoter. The interaction between Sp1 and hTERT promoter DNA was significantly reduced in response to ceramide as assessed by chromatin immunoprecipitation analysis. In contrast, the promoter DNA-binding activity of Sp3 was slightly increased in response to C6-ceramide, resulting in the increased ratio of Sp3/Sp1 on the hTERT promoter, which was concomitant with the reduced recruitment of RNA polymerase II to the promoter. Furthermore, mutations of various Sp1/Sp3 recognition sequences significantly attenuated the activity of the promoter in the presence or absence of ceramide, demonstrating the importance of multiple Sp1/Sp3 recognition sites for the promoter activity. Mechanistically, the data demonstrated that C6-ceramide reduced the acetylation of Sp3 protein and partially blocked the activation of the hTERT promoter by the histone deacetylase inhibitor trichostatin A. The roles of endogenous long chain ceramide generated in response to gemcitabine in the inhibition of hTERT promoter activity and the regulation of Sp3 acetylation were also demonstrated.
...
PMID:Sp1/Sp3-dependent regulation of human telomerase reverse transcriptase promoter activity by the bioactive sphingolipid ceramide. 1595 64

Glucocorticoids are the most effective anti-inflammatory drugs used in the treatment of inflammatory diseases. While phosphorylation of histone H3 at serine 10 (p-Ser10) is one of the histone modifications related to transcription of some inflammation-related genes, the effect of glucocorticoids on p-Ser10 is not established. Here, we investigated the ability of dexamethasone (Dex) to inhibit p-Ser10 expression in response to tumor necrosis factor (TNF-alpha) in the human lung adenocarcinoma cell line A549 and the SV-40-transformed human airway epithelial cell line BEAS-2B. By Western blot analysis in BEAS-2B cells, the expression of p-Ser10 was repressed by pretreatment with Dex, an effect not seen in A549 cells. Flow cytometric analysis at a single-cell level in A549 cells indicated that TNF-alpha treatment caused early induction of p-Ser10 at 15 min, which was inhibited significantly by pretreatment with 10(-5) M Dex. By immunostaining, the p-Ser10 signal appeared as granules in TNF-alpha-treated cells at same sites of phosphorylated RNA polymerase II. In contrast, the signal was scattered in the nuclei of Dex-pretreated cells. These findings suggested that Dex limits airway inflammation by inhibiting p-Ser10 expression and redistributing p-Ser10 away from transcription sites.
...
PMID:Dexamethasone inhibits phosphorylation of histone H3 at serine 10. 1616 91

Receptors for gut hormones, which are often overexpressed in cancer, are clinically relevant for receptor-targeted tumor imaging and therapy. Because the receptors for the gut hormone secretin are poorly characterized, we assessed secretin receptor expression in the main secretin target, the human pancreas. We investigated 58 non-neoplastic pancreases and 55 pancreatic tumors for receptor localization and density by in vitro receptor autoradiography using [(125)I]Tyr(10) rat secretin and for secretin receptor mRNA by reverse transcriptase-polymerase chain reaction. Secretin receptors were highly expressed in non-neoplastic ducts and lobuli and also in lower amounts in ductal neoplasias, including ductal adenocarcinoma, intraductal papillary mucinous tumors, and pancreatic intraepithelial neoplasia. Reverse transcriptase-polymerase chain reaction revealed wild-type receptor mRNA in the non-neoplastic pancreas and both wild-type and spliced variant receptor transcripts in ductal adenocarcinomas. Serous cystic tumors were highly positive for secretin receptors, whereas mucinous cystic tumors were negative. This study is the first to describe the precise secretin receptor distribution in human non-neoplastic pancreas and various pancreatic tumors. High secretin receptor expression in the non-neoplastic ducts reflects the major role of secretin in bicarbonate secretion. Reduced secretin binding in pancreatic ductal tumors may relate to (alternatively spliced) secretin receptor isoforms. Thus, secretin receptors in pancreatic tumors may represent potential clinical targets.
...
PMID:Secretin receptors in normal and diseased human pancreas: marked reduction of receptor binding in ductal neoplasia. 1619 32

Human telomerase is a ribonucleoprotein complex composed of at least the reverse catalytic transcriptase hTERT and RNA component hTR. The enzyme stabilizes telomere length and thereby contributes to unlimited cell proliferation, i.e. immortality. Reactivation of telomerase activity during carcinogenesis is a common hallmark in most human tumor types. Consequently, telomerase is an attractive molecular target toward which to direct cancer therapeutic agents. RNA interference (RNAi) has been shown to be an effective method for inhibiting the expression of a given gene in human cells by targeting with short duplex RNA (short-interfering RNA or siRNA). Thus, we evaluated the ability of siRNAs to inhibit telomerase activity in the HT29 immortal human colorectal adenocarcinoma cell line as a model for colorectal carcinogenesis. By transient expression of a specific siRNA directed against hTERT, we reduced telomerase activity in the transfected cells. Moreover, telomere lengths were reduced in cells stably expressing this particular RNA sequence, cloned as an shRNA into an eukaryotic expression vector. The cell clone that displayed a telomerase-negative phenotype showed dramatically reduced telomere lengths and stopped proliferation. We observed that the vector was integrated into the cell genome and, despite telomere shortening, cells retained their MSI phenotype. We conclude that we have developed a potent telomerase inhibitor leading to cell death.
...
PMID:Telomerase inhibition by an siRNA directed against hTERT leads to telomere attrition in HT29 cells. 1682 Sep 26

Aptamers offer advantages over other oligonucleotide-based approaches that artificially interfere with target gene function due to their ability to bind protein products of these genes with high affinity and specificity. However, RNA aptamers are limited in their ability to target intracellular proteins since even nuclease-resistant aptamers do not efficiently enter the intracellular compartments. Moreover, attempts at expressing RNA aptamers within mammalian cells through vector-based approaches have been hampered by the presence of additional flanking sequences in expressed RNA aptamers, which may alter their functional conformation. In this report, we successfully expressed a 'pure' RNA aptamer specific for NF-kappaB p50 protein (A-p50) utilizing an adenoviral vector employing the H1 RNA polymerase III promoter. Binding of the expressed aptamer to its target and subsequent inhibition of NF-kappaB mediated intracellular events were demonstrated in human lung adenocarcinoma cells (A549), murine mammary carcinoma cells (4T1) as well as a human tumor xenograft model. This success highlights the promise of RNA aptamers to effectively target intracellular proteins for in vitro discovery and in vivo applications.
...
PMID:H1 RNA polymerase III promoter-driven expression of an RNA aptamer leads to high-level inhibition of intracellular protein activity. 1685 94

Polyamine analogs are known to inhibit tumorigenesis at least in part by mimicking some of the regulatory roles of natural polyamines. To begin the identification of those signaling pathways that are involved in differential cellular responses to the synthetic conformationally restricted polyamine analog CGC-11093, we conducted gene expression profiling, proteomic, and genome-wide DNA methylation and histone acetylation analyses of the HCT116 colon adenocarcinoma cell line after treatment with this analog. Gene expression analysis was performed using Affymetrix GeneChip human genome U133 Plus 2.0 arrays. Changes in protein expression were evaluated using 2D polyacrylamide gels followed by LCMS/MS. DNA methylation was measured using 6,800 element CpG island microarrays. Treatment of cells with CGC-11093 at concentrations ranging from 0.1 to 10 microM caused inhibition of cell growth and metabolic activity, but only minimally affected cell viability. Gene expression analysis showed concentration-dependent effects of CGC-11093 on the DNA/RNA binding transcription factor, cell cycle, signaling, transport, cytoskeletal/structural, and serine protease genes. Functional gene analysis revealed distinct expression patterns related to inhibition of cell cycle control, TGF beta signaling, proteasome and RNA polymerase pathways, upregulation of the aminoacyl-tRNA synthesis pathway, and perturbations in the MAPK and Wnt signaling pathways. Microarray results were validated for selected genes with real time RT PCR. Proteomics analysis showed correlative changes in the expression of proteins involved in the regulation of proteasome function (proteasome subunit Y) and tRNA synthesis. CGC-11093 treatment did not produce any detectable changes in DNA methylation or histone acetylation in cells. This study validates specific target pathways for a specific conformationally restricted polyamine analog and suggests the utility of combined gene and DNA methylation microarrays along with proteomic analyses as a useful approach to the evaluation of the mechanisms of action of anticancer drugs.
...
PMID:Pharmacogenomics of the polyamine analog 3,8,13,18-tetraaza-10,11-[(E)-1,2-cyclopropyl]eicosane tetrahydrochloride, CGC-11093, in the colon adenocarcinoma cell line HCT1161. 1712 31

Intraductal papillary mucinous neoplasm (IPMN) is a well-established entity in pancreatic neoplasms and a precursor of infiltrating adenocarcinoma. Fascin, an actin-bundling protein involved in cellular motility, is upregulated in many human neoplasms. Its overexpression in pancreatic intraepithelial neoplasia, a pre-cancerous lesion sharing many characteristics with IPMN, has been reported. However, fascin expression in IPMN remains unknown. The aim of this study was to investigate fascin expression in IPMNs and to elucidate its relationship to clinicopathological features, including histological grade and phenotypic subclassification. We evaluated fascin expression by immunohistochemistry in 116 surgical specimens, followed by quantitative analysis of fascin mRNA expression using a laser microdissection system and real-time reverse-transcriptase polymerase chain reaction in eight frozen samples. Fascin expression was significantly higher in borderline neoplasms (25/29, 86%) and carcinomas (37/42, 88%) than in adenomas (23/45, 51%) (P<0.05, respectively), but no difference was observed between borderline neoplasms and carcinomas. With regard to the subclassification, intestinal-type neoplasms (35/39, 90%) were more frequently positive for fascin than gastric-type neoplasms (36/59, 61%) (P<0.05). Two oncocytic-type neoplasms were both fascin-negative. Fascin mRNA expression seemed to be higher in moderately to severely dysplastic epithelium than in mildly dysplastic epithelium (not statistically significant), supporting the immunohistochemical experiments. Our findings suggest that fascin overexpression is involved in the progression of IPMN. Fascin could become a new therapeutic target for inhibition of their progression.
...
PMID:Fascin overexpression in intraductal papillary mucinous neoplasms (adenomas, borderline neoplasms, and carcinomas) of the pancreas, correlated with increased histological grade. 1739 45

The biological role of 1,25-dihydroxyvitamin D(3) has generally been related to calcium homeostasis, but this hormone also has fundamental effects on processes of cellular proliferation and differentiation. The genomic actions of 1,25-dihydroxyvitamin D(3) are mediated by the vitamin D receptor (VDR) present in target cells. However, VDR transcriptional regulation is not well understood, probably attributable to the complexity of the VDR gene and its promoter. In the present study, it is demonstrated that administration of the pituitary transcription factor Pit-1 (originally found in the pituitary gland but also present in other nonpituitary cell types and tissues) to the MCF-7 (human breast adenocarcinoma) cell line induces a significant increase in VDR mRNA and protein levels. Conversely, Pit-1-targeted small interference RNA markedly reduced expression of VDR in MCF-7 cells. Reporter gene assays demonstrated that the effect of Pit-1 is mediated by its binding to a region located between -254 and -246 bp from the VDR transcription start site. Selective mutations of this site completely abolished VDR transcription. Chromatin immunoprecipitation analysis showed that binding of Pit-1 to the VDR promoter leads additionally to recruitment of cAMP response element-binding protein binding protein, acetylated histone H4, and RNA polymerase II. Surprisingly, Pit-1 binding also recruits VDR protein to the VDR promoter. Using several cell lines with different levels of VDR expression, it was demonstrated that up-regulation of VDR transcription by Pit-1 is dependent on the presence of VDR protein, suggesting that transcriptional expression of VDR in a given cell type is dependent on, among other factors, its own expression levels.
...
PMID:Cellular expression levels of the vitamin D receptor are critical to its transcriptional regulation by the pituitary transcription factor Pit-1. 1745 92

In this study, distinct roles of de novo-generated endogenous ceramides and mechanisms by which deacetylated Sp3 regulates the hTERT promoter activity in response to ceramide signaling were explored. The generation of C18-ceramide via the expression of ceramide synthase 1 (CerS1), and not C16-ceramide by CerS5 or CerS6 expression, resulted in repression of the hTERT promoter via deacetylation of Sp3 by histone deacetylase 1 (HDAC1) in A549 human lung adenocarcinoma cells. Then roles and mechanisms of action of ceramide-mediated deacetylation of Sp3 in inhibiting the hTERT promoter were determined using constitutively deacetylated or acetylated Sp3 mutants at lysine (K) 551. Expression of the deacetylated Sp3 mutant resulted in repression, whereas its acetylated mutant induced basal hTERT promoter activity in Drosophila S2 cells, which do not express any endogenous Sp3, and in A549 cells. Remarkably, chromatin immunoprecipitation data revealed that acetylated Sp3 mutant (K551Q-Sp3) did not bind whereas deacetylated Sp3 (K551R-Sp3) mutant bound strongly to the promoter DNA, resulting in the recruitment of histone deacetylase 1 (HDAC1) and inhibition of the association of RNA polymerase II with the promoter. Mechanistically, increased generation of C18-ceramide by hCerS1 expression, but not by its catalytically inactive mutant, mediated the association and recruitment of the deacetylated Sp3/HDAC1 complex to the hTERT promoter DNA, resulting in the local histone H3 deacetylation and repression of the promoter.
...
PMID:Mechanisms of ceramide-mediated repression of the human telomerase reverse transcriptase promoter via deacetylation of Sp3 by histone deacetylase 1. 1754 28

Prolonged activation of NF-kappaB is involved in the pathogenesis of chronic inflammatory diseases and associated cancers. NF-kappaB activation is considered to be a main mechanism opposing TNFalpha-induced apoptosis. We investigated whether inhibition of NF-kappaB could sensitize tumor and endothelial cells to TNFalpha-induced apoptosis. As such, we developed a novel H1 RNA polymerase III promoter driven adenoviral vector to express an RNA aptamer, Ad-A-p50, which selectively inhibits NF-kappaB activation in the nucleus. This event sensitizes human lung adenocarcinoma cells (A549) and human endothelial cells (HUVEC) to TNFalpha-induced apoptosis through the multiple pathways regulated by NF-kappaB, including Bcl-XL, HIF-1alpha, and VEGF. Our findings also suggest a new mechanism of HIF-1alpha regulation by NF-kappaB in the normoxic environment. RNA aptamer inhibition of NF-kappaB offers exciting opportunities for sensitizing inflammatory and tumor cells to TNFalpha-induced apoptosis.
...
PMID:NF-kappaB inhibition by an adenovirus expressed aptamer sensitizes TNFalpha-induced apoptosis. 1756 May 52


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---