Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Disseminated tumor cells (DTC) are a potential contributor to relapse of cancer. In the present study we developed a model for induction of disseminated tumor cells in nude mice, which can aid in the search for therapeutic approaches as well as improve our understanding of metastasizing gastric cancer. To detect DTC in blood and bone marrow we established a modified animal model of orthotopic transplantation. Two groups of nude mice were used for xenotransplantation of gastric cancer specimens. In group I tumor specimens originating from a gastric adenocarcinoma cell line were transplanted onto the stomach; in group II they were transplanted subcutaneously into both axillaries. Tumor growth, metastases and presence of DTC were compared in both groups. For detection of DTC a nested reverse transcriptase polymerase chain reaction (RT-PCR) for human cytokeratin (CK)-20 was performed on blood and bone marrow of all mice. Tumor growth occurred in both groups (9/10 animals in group I, 10/10 in group II) within 14 weeks. Only animals in group I developed local invasive tumor growth, stenosis of the stomach and distant metastases. Tumors in animals of group II grew with local displacement only and developed no metastases. There were no signals of CK-20 detected in the blood in both groups. In group I, 5 of 9 animals had positive signals of human CK-20 in their bone marrow as a sign of DTC. In group II no DTC were detected in bone marrow. We conclude that orthotopic transplantation is a prerequisite for the development of DTC and metastasizing tumor growth in this modified gastric cancer model.
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PMID:Detection of disseminated tumor cells in nude mice with human gastric cancer. 1459 89

Expression of E1AF/PEA3 (ETV4), an ets family transcriptional factor, has been implicated in tumor progression through induction of matrix metalloproteinase (MMP) expression. The aim of this study was to examine E1AF mRNA expression and to determine whether it is correlated with progression of, and/or MMP expression in, human gastric cancer. Using the semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we analyzed 100 gastric cancer tissues for E1AF mRNA expression. Expression of ER81 (ETV1) and ERM (ETV5), the other two members of the PEA3 subfamily, and Ets-1 and Ets-2 was also analyzed. The results were correlated with clinicopathological characteristics and MMP expression. Immunohistochemical analysis and an in vitro invasion assay were also performed. E1AF mRNA expression was detected in 64% of the 100 gastric cancer tissues, but was undetectable or only faintly detected in adjacent non-tumor tissues. E1AF expression was significantly correlated with depth of invasion, lymphatic and venous invasion, lymph node and distant metastasis, advance in pathological tumor-node-metastasis stage and recurrence. Patients with E1AF-positive tumors had significantly shorter overall and disease-free survival periods than did those with E1AF-negative tumors (P < 0.0001 and P < 0.0001, respectively). E1AF expression retained its significant predictive value for overall and disease-free survival in multivariate analysis that included conventional clinicopathological factors (P = 0.0082 and P = 0.0096, respectively). Among the MMPs analyzed, expression of matrilysin (MMP-7) was significantly correlated with E1AF expression. Immunohistochemical expression of E1AF was predominantly observed at the invasive front, where the expression of matrilysin was often co-localized. Antisense E1AF-transfected MKN45 gastric cancer cells expressed reduced levels of matrilysin and were less invasive in vitro than mock-transfected MKN45 cells. The results of this study suggest that E1AF, the expression of which is closely correlated with the expression of matrilysin, plays a key role in the progression of gastric cancer.
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PMID:Expression of ets-related transcriptional factor E1AF is associated with tumor progression and over-expression of matrilysin in human gastric cancer. 1460 92

We previously performed a global analysis of the gene expression of gastric cancer cell lines established from metastases to the peritoneal cavity with the cDNA microarray method, which made it possible to analyse the expression of approximately 21168 genes for the identification of novel markers for the detection of micrometastases in the peritoneal cavity. One of the upregulated genes is dopa decarboxylase (DDC), which is responsible for the synthesis of the key neurotransmitters dopamine and serotonine. We have examined its potential as a novel marker for the detection of peritoneal micrometastases of gastric cancer.DDC mRNA in the peritoneal wash from 112 gastric cancer patients was quantified for comparison of carcinoembryonic antigen (CEA) mRNA by means of real-time reverse transcriptase-polymerase chain reaction (RT-PCR) with a fluorescently labelled probe to predict peritoneal recurrence. The quantity of DDC and CEA correlated with wall penetration. Real-time RT-PCR could quantitate 10-10(6) DDC-expressing gastric cancer cells per 10(7) mesothelial cells. The cutoff value was set at the upper limit of the quantitative value for noncancer patients, and those above this cutoff value constituted the micrometastasis (MM+) group. Of 15 cases with peritoneal dissemination, 13 were MM+DDC (87% sensitivity), and one of 48 t1 cases was MM+ (98% specificity). DDC levels in peritoneal washes from patients with synchronous peritoneal metastases were more than 50 times higher than in those from patients without metastasis (P<0.01). For 15 cases of peritoneal dissemination (seven cases were cytologically positive), DDC was positive in 13 cases (87% sensitivity), but CEA failed to detect micrometastases in four cases (73% sensitivity), indicating that DDC is in some cases superior to CEA for the detection of peritoneal micrometastases of gastric cancer in terms of sensitivity as well as specificity, especially for poorly differentiated adenocarcinomas. A combination of CEA and DDC improved the accuracy of diagnosis up to 94%. These results suggest that DDC is potentially a novel marker for peritoneal dissemination of gastric cancer and that quantitative RT-PCR of DDC is reliable and efficient for the selection of patients for adjuvant intraperitoneal chemotherapy to prevent peritoneal recurrence.
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PMID:Overexpression of dopa decarboxylase in peritoneal dissemination of gastric cancer and its potential as a novel marker for the detection of peritoneal micrometastases with real-time RT-PCR. 1476 Mar 82

The enzyme inducible nitric oxide synthase (iNOS) is part of the host innate defense system against bacterial infection. During chronic inflammation, like that seen with a Helicobacter pylori infection, constant nitric oxide production may lead to tissue and DNA damage, thus increasing the patient's risk for developing cancer. Several investigations on iNOS expression in H. pylori-associated gastritis have resulted in conflicting data. Therefore, we investigated the association between chronic H. pylori infection and iNOS expression in samples from stomach carcinoma patients as well as in antral biopsies from patients with H. pylori-associated gastritis. iNOS expression was analyzed by means of reverse transcriptase (RT)-PCR and quantified by competitive RT-PCR. To study in situ localization of iNOS in biopsy samples, immunohistochemistry was performed. iNOS enzyme activity was quantified using an arginine/citrulline assay. A significant increase in iNOS mRNA signal was only present in one-third of the analyzed patient biopsies with H. pylori-associated gastritis. These biopsies showed a 90% association with intestinal metaplasia and a 100% association with CagA-positive H. pylori. Intestinal metaplasia is discussed to be one step in the carcinogenesis of stomach cancer. Quantitation of iNOS transcripts and iNOS enzyme activity in non-cancerous mucosa of gastric cancer patients revealed a significant increase in iNOS transcripts and iNOS activity only in the mucosa of patients with stomach cancer of the intestinal type but not in the diffuse type. Our results support the hypothesis that CagA-positive H. pylori strains are associated with the expression and activity of iNOS, and therefore might contribute to the development of intestinal metaplasia leading to gastric cancer of the intestinal type.
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PMID:Up-regulation of inducible nitric oxide synthase in Helicobacter pylori-associated gastritis may represent an increased risk factor to develop gastric carcinoma of the intestinal type. 1476 Sep 71

Traditional Chinese medicinal plants are a treasure house for screening novel inhibitors of DNA polymerases and DNA topoisomerases from mammals; in the present study, nine lanostane-type triterpene acids were found in sclerotium of Poria cocos. Among the nine compounds, only dehydroebriconic acid could potently inhibit DNA topoisomerase II (topo II) activity (IC(50) = 4.6 microM), while the compound moderately inhibited the activities of DNA polymerases alpha, beta, gamma, delta, epsilon, eta, iota, kappa and lambda only from mammals, to similar extents. Another compound, dehydrotrametenonic acid, also showed moderate inhibitory effects against topo II (IC(50) = 37.5 microM) and weak effects against all the polymerases tested. Both compounds showed no inhibitory effect against topo I, higher plant (cauliflower) DNA polymerase I (alpha-like polymerase) or II (beta-like polymerase), calf thymus terminal deoxynucleotidyl transferase, human immunodeficiency virus type-1 reverse transcriptase, prokaryotic DNA polymerases such as the Klenow fragment of E. coli DNA polymerase I, Taq DNA polymerase and T4 DNA polymerase, or DNA metabolic enzymes such as T 7 RNA polymerase, T4 polynucleotide kinase and bovine deoxyribonuclease I. These findings suggest that dehydroebriconic acid and dehydrotrametenonic acid should be designated as topo II-preferential inhibitors, although they also moderately inhibited all the mammalian DNA polymerases tested. Both dehydrotrametenonic acid and dehydroebriconic acid could prevent the growth of human gastric cancer cells, and their LD(50) values were 63.6 and 38.4 microM, respectively. The cells were halted at the G1 phase in the cell cycle. The relation between the structure of triterpene acids and their inhibitory activities is discussed.
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PMID:A novel DNA topoisomerase inhibitor: dehydroebriconic acid, one of the lanostane-type triterpene acids from Poria cocos. 1507 95

Gastric carcinomas can be classified into scirrhous carcinomas (SC), i.e. 'linitis plastica' or Borrmann 4 gastric cancer, and non-scirrhous carcinomas (NSC). SC are characterized by diffuse invasive growth patterns with marked fibrosis, frequent peritoneal dissemination and lymph-node metastases and poor prognosis, while NSC show medullary growth patterns and common hematogenous metastases. To study the differences in local expression levels of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) between SC and NSC, we examined the expression of MMPs and TIMPs in human gastric carcinoma tissues by several methods including sandwich-enzyme immunoassay systems, gelatin zymography, reverse transcriptase-polymerase chain reaction (RT-PCR), real-time quantitative PCR, immunoblotting, immunohistochemistry and in situ zymography. Of the seven MMPs and two TIMPs tested, only proMMP-2 levels were remarkably higher in SC than in NSC (P < 0.01), and proMMP-2 activation ratio was significantly lower in SC than in NSC (P < 0.05). TIMP-3 mRNA levels were remarkably about 2-fold higher in SC than in NSC tissues (P < 0.01). TIMP-3 production in SC was confirmed by immunoblotting and TIMP-3 was immunolocalized to stromal fibroblasts in SC. TIMP-3 mRNA levels inversely correlated with proMMP-2 activation ratios, although the expression levels of MT1-MMP and MT2-MMP were not different in SC and NSC. By in situ zymography, gelatinolytic activity appeared to be weaker in SC than in NSC. All these data suggest that proMMP-2 activation is down-regulated by TIMP-3 expressed in scirrhous gastric carcinomas. Our findings may explain the differences in clinical behaviors of SC and NSC.
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PMID:Differences between scirrhous and non-scirrhous human gastric carcinomas from the aspect of proMMP-2 activation regulated by TIMP-3. 1538 72

We previously performed a global analysis of the gene expression of gastric cancer cell lines established from peritoneal dissemination (SNU-5, SNU-16, SNU-719, KATO-III and GT3TKB) with the cDNA microarray method to identify the novel markers for the detection of micro-metastasis in peritoneal cavity. One of the up-regulated genes is Reg IV, which is a member of the Reg gene family belonging to calcium dependent lectin (C-type lectin) gene superfamily. We have examined Reg IV potential as a novel marker for the detection of peritoneal micro-metastases of gastric cancer. Reg IV expression was examined in five gastric cancer cell lines established from peritoneal dissemination and compared with myeloid leukemia cell (HL60), methothelial cell lines Met5A and the other gastric cell line established from primary tumor (SNU-1) by quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Reg IV was highly overexpressed in 4 gastric cancer cell lines established from peritoneal dissemination, but weakly expressed in other cell lines. According to Reg IV mRNA expression levels in surgically resected specimens, the quantity of Reg IV correlated with wall penetration. Furthermore, Reg IV mRNA expression level in the peritoneal wash from 35 gastric cancer patients was also prone to correlation with wall penetration. These results suggest that Reg IV may be involved in peritoneal dissemination of gastric cancers and Reg IV may be a potential novel marker for peritoneal dissemination of gastric cancers.
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PMID:[Over expression of Reg IV in peritoneal dissemination of gastric cancer]. 1555 56

Our previous studies suggest that a lack of RUNX3 function is causally related to the genesis and progression of human gastric cancer. This study was conducted to determine whether alteration of RUNX3 gene expression could be detected in the normal-looking gastric remnant mucosa, and to ascertain any difference in the potential of gastric carcinogenesis between the anastomotic site and other areas in the remnant stomach after distal gastrectomy for peptic ulcer (RB group) or gastric cancer (RM group), by analysing RUNX3 expression with special reference to topography. A total of 89 patients underwent distal gastrectomy for gastric cancer from the intact stomach (GCI group) and 58 patients underwent resection of the remnant stomach for gastric cancer (RB group: 34 cases, RM group: 24 cases). We detected RUNX3 and gene promoter methylation by in situ hybridisation, quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), and methylation-specific PCR. The interval between the initial surgery and surgery for remnant gastric cancer (interval time) was 10.4 years in the RM group, and 27.5 years in the RB group. Cancers in the RB group were significantly more predominant in the anastomosis area (P<0.05). Within the tumour, downregulation of RUNX3 expression ranged from 74.7 to 85.7% in the three groups. The rate of downregulation of RUNX3 of adjacent mucosa was 39.2% (11 in 28 cases) in RB and 47.6% (10 in 21 cases) in RM, which are significantly higher than that of the GCI group (19.5%, 17 in 87 cases). In noncancerous mucosa of the remnant stomach in the RB group, RUNX3 expression decreased more near the anastomosis area. In the RM group, however, there were no significant differences in RUNX3 expression by sampling location. Based on RUNX3 downregulation and clinical features, residual stomach mucosa of the RM group would have a higher potential of gastric carcinogenesis compared to the RB or GCI group. Gastric stump mucosa of the RB group has higher potential especially than other areas of residual stomach mucosa. Measurement of RUNX3 expression and detection of RUNX3 methylation in remnant gastric mucosa may estimate the forward risk of carcinogenesis in the remnant stomach.
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PMID:Frequent loss of RUNX3 gene expression in remnant stomach cancer and adjacent mucosa with special reference to topography. 1568 35

Malignant cells have been reported to escape immune surveillance by modulation of human lymphocyte antigen (HLA) class Ia molecule and/or other accessory molecules like TAP (transporter associated with antigen processing) and beta2-M expression. Most of these reports, however, are based on immunohistochemistry techniques with polymorphic- or isotype-specific antibodies. In the present study, we have instead used a locus-specific reverse transcriptase-polymerase chain reaction-based approach to detect the transcriptional expression of HLA class Ia as well as accessory molecules in gastric cancer. Our results indicate that HLA class Ia transcript is totally absent in only approximately 9% of cancer cases. Locus-specific expression of HLA-A and -B could, however, be detected in approximately 54% cases, whereas HLA-C was expressed in most of the cancer tissues. Interestingly, in some cases where HLA class Ia expression was observed, TAP1 expression could not be detected. Furthermore, we also investigated the frequency of nonclassical or HLA class Ib expression for molecules such as HLA-E and -G. HLA-G transcript was absent in gastric tissues both in cancerous and autologous normal region, whereas HLA-E was observed in a number of gastric cancers. Altogether these selective locus-specific losses of HLA class I along with impaired expression of accessory molecules may explain the complex phenomena by which gastric tumors escape both cytotoxic T-lymphocyte- as well as natural killer cell-mediated immune defense.
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PMID:Analysis of human lymphocyte antigen class I expression in gastric cancer by reverse transcriptase-polymerase chain reaction. 1569 2

Nucleostemin (NS) is a novel protein that promotes the proliferation of stem cells and cancer cells. The aim of this study is to prepare specific monoclonal antibodies against nucleostemin as a tool in nucleostemin research. To generate the antibodies, the cDNA coding nucleostemin was cloned from human gastric cancer cell line NCI-N87 with reverse transcriptase-polymerase chain reaction (RT-PCR). The partial cDNA fragment was inserted into prokaryotic expression vector pGEX-4T1 to make glutathione S-transferase (GST) fusion protein in Escherichia coli, and the whole-length cDNA fragment was cloned into vector pcDNA3 for expression in mammalian cells. The spleen cells, from the BALB/c mouse immunized with the GST-nucleostemin fusion protein, were used to prepare the monoclonal antibody with hybridoma technique. After screening with enzyme-linked immunosorbent assay (ELISA) and subcloning, six specific monoclonal antibodies against nucleostemin were obtained. Moreover, they also worked well in Western blotting, immunoprecipitation, and immunohistochemistry. These antibodies will be helpful in elucidating biological functions and the molecular mechanism of nucleostemin.
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PMID:Preparation and characterization of monoclonal antibodies against nucleostemin, a protein that controls cell proliferation in stem cells and cancer cells. 1578 7


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