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

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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)

The p16 (CDKN2,MTS1) gene is located at 9p21 and its product, p16, inhibits the cyclin D/CDK4 complex. Loss of heterozygosity on chromosome 9p is very common in human bladder carcinomas and has been found in all stages of lesions, suggesting that it occurs early in bladder tumor progression. Several studies have revealed frequent homozygous deletion of the p16 gene in cell lines, and that such deletions are also common in some types of cancers. In addition, point mutations in the p16 gene have been identified in several types of neoplasia. In the present examination of urinary bladder tumors, no p16 gene mutations were detected, but nine cases out of 23 (39%) showed decreased mRNA expression, revealed by the reverse transcriptase polymerase chain reaction. There were no histological differences apparent between those cases with normal and those with decreased p16 expression. These results indicate that while p16 gene mutations may be rare, changes in the level of the p16 transcripts could play a role in human bladder carcinoma development.
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PMID:Decreased expression of the p16/MTS1 gene without mutation is frequent in human urinary bladder carcinomas. 907 Mar 36

Overexpression of p185erbB2/neu has been detected in many adenocarcinomas, including prostatic cancer. In this study, a nontumorigenic cell line isolated from the rat prostatic epithelium (NbE) transfected with the activated oncogene p185neu-T was used to investigate the role of this oncogene in tumor progression. When clones overexpressing p185neu-T were injected orthotopically (1.5 to 2 x 10(6) cells) into the dorsal-lateral prostates of nude mice, prostatic tumors were detected in all mice injected and metastasis to the skeletal muscle in the rib area in 60-80% of the mice injected. Tumor and metastasis origin was confirmed by reselection with G418 and reverse transcriptase-polymerase chain reaction. Control cell lines produced no prostatic tumors or metastases. Incubation at low density (12500 cells/2 cm2) in serum-free medium revealed that clones overexpressing p185neu-T had a higher rate of [3H]thymidine incorporation than did control clones on 3, 5, and 7 d after plating (P < or = 0.0001) and constitutively overexpressed the 2.6-kb ornithine decarboxylase transcript. Additionally, clones overexpressing p185neu-T demonstrated an increased expression of epidermal growth factor receptor and p180erbB4, as judged by RNA blot analysis. Together these data support the hypothesis that overexpression of p185neu-T fosters tumor progression by several pathways, including induction of the metastatic cascade, increased proliferative capabilities, and increased expression of other members of the erbB2 gene family.
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PMID:Metastasis induced by overexpression of p185neu-T after orthotopic injection into a prostatic epithelial cell line (NbE). 925 83

The clinical behavior of growth hormone (GH)-producing pituitary tumors is known to vary greatly; however, the events underlying this variability remain poorly understood. Herein we demonstrate that tumor overexpression of the GH-releasing hormone (GHRH) gene is one prognostically informative event associated with the clinical aggressiveness of somatotroph pituitary tumors. Accumulation of GHRH mRNA transcripts was demonstrated in 91 of a consecutive series of 100 somatotroph tumors by in situ hybridization; these findings were corroborated by Northern analysis and reverse transcriptase polymerase chain reaction, and protein translation was confirmed by Western blotting. By comparison, transcript accumulation was absent or negligibly low in 30 normal pituitary glands. GHRH transcripts were found to preferentially accumulate among clinically aggressive tumors. Specifically, GHRH mRNA signal intensity was 1) linearly correlated with Ki-67 tumor growth fractions (r = 0.71; P < 0.001), 2) linearly correlated with preoperative serum GH levels (r = 0.56; p = 0.01), 3) higher among invasive tumors (P < 0.001), and 4) highest in those tumors in which post-operative remission was not achieved (P < 0.001). Using multivariate logistic regression, a model of postoperative remission likelihood was derived wherein remission was defined by the single criterion of suppressibility of GH levels to less than 2 ng/ml during an oral glucose tolerance test. In this outcome model, GHRH mRNA signal intensity proved to be the most important explanatory variable overall, eclipsing any and all conventional clinicopathological predictors as the single most significant predictor of postoperative remission; increases in GHRH mRNA signal were associated with marked declines in remission likelihood. The generalizability of this outcome model was further validated by the model's significant performance in predicting postoperative remission in a random sample of 30 somatotroph tumors treated at another institution. These data indicate that overexpression of GHRH gene is an event associated with the neoplastic progression and clinical aggressiveness of somatotroph adenomas. More generally, these data merge essential elements of the hypothalamic and pituitary hypotheses of pituitary tumorigenesis, providing for a more unified concept of neoplastic progression in the pituitary.
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PMID:Overexpression of the growth-hormone-releasing hormone gene in acromegaly-associated pituitary tumors. An event associated with neoplastic progression and aggressive behavior. 928 26

Understaging is commonly associated with therapeutic failure of surgical intervention in apparently localized prostate cancers. Methods that specifically detect prostate cancer cells in the circulation may be able to identify metastatic cancers and thus aid in the selection of the most adequate therapy. The high sensitivity and specificity of the reverse transcriptase-polymerase chain reaction (RT-PCR) encouraged various groups to investigate the mRNA expression of prostate-specific markers in the peripheral blood of patients with prostate cancer. However, probably due to methodological differences, many contradictory results have been obtained with the markers studied so far: prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM). For this reason, clinical decisions should not be based yet on RT-PCR results. Future research and long-term follow-up on the patients may point out whether RT-PCR assays, following appropriate standardization, will have an additive value in prostate cancer staging and in prediction of tumor progression.
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PMID:Clinical usefulness of RT-PCR detection of hematogenous prostate cancer spread. 944 45

Expression of HLA class I molecules is essential for the recognition of tumor cells by CD8+ T cells. In this study, 48 bioptic samples of 42 patients in all stages of melanoma were investigated after short-time cultivation of tumor cells. To confirm melanocytic origin of cultured cells, samples were screened for mRNA expression of melanoma markers gp100, tyrosinase, MAGE-3, MelanA, and MUC18 by reverse transcriptase-polymerase chain reaction. Surface expression of specific HLA-A and -B allospecificities on melanoma cells were analyzed with a standard microcytotoxicity assay after stimulation with interferon (IFN)-alpha and compared with the background found in peripheral blood mononuclear cells from the corresponding patients. Immunohistochemistry and flow cytometry confirmed specific losses in cases where the appropriate monoclonal antibodies were available. The level of expression of HLA-I, HLA-II, and intercellular adhesion molecule 1 antigens on melanoma cells cultured in the presence or absence of IFN-alpha and IFN-gamma was determined cytofluorometrically. All cell cultures tested were found to be positive for one or more melanocytic markers by reverse transcriptase-polymerase chain reaction. The specific HLA-I alleles on the cultured cells were detectable in 45 of 48 samples. In 11 cases a specific loss of one HLA-I allele was observed (2 x A2, B7, B8, B18, 4XB44, B47, B49). Ten of these samples were derived from locoregional lymphnode metastases or from distant metastatic tumors. Only one sample from a primary melanoma showed a specific loss of HLA-I (B47). IFN-alpha upregulated expression of HLA-I up to 4-fold. IFN-gamma enhanced the appearance of HLA-II up to 35-fold and the expression of intercellular adhesion molecule 1 up to 40-fold. Selective loss of HLA-I allospecificities might be a major step in tumor progression.
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PMID:Higher frequency of selective losses of HLA-A and -B allospecificities in metastasis than in primary melanoma lesions. 974 Feb 47

Several members of the transmembrane 4 superfamily (TM4SF) have been reported to be related to tumor progression and metastasis. The aims of our study were to clarify the relationship between TM4SF and pancreatic cancer and to determine the prognostic significance of TM4SF in human pancreatic cancer. The mRNA levels for MRP-1/CD9, KAI1/CD82 and ME491/CD63, which belong to the TM4SF gene family, were evaluated in 40 resectable pancreatic adenocarcinomas using reverse transcriptase-PCR. MRP-1/CD9 gene expression was associated with lymph node status, and with pathological status. Moreover, MRP-1/CD9 expression was inversely associated with histo-pathological grading. KAI1/CD82 gene expression was inversely associated with tumor status. ME491/CD63 gene expression, however, was conserved in all pancreatic cancers. The overall survival rate for the 22 patients whose tumors had decreased MRP-1/CD9 gene expression was strikingly lower than that for the 18 patients with MRP-1/CD9-positive tumors. The overall survival rate of the 15 patients who were KAI1/CD82-positive was significantly higher than that of the 25 patients with decreased KAI1/CD82 gene expression. In a multivariate analysis using the Cox proportional hazards model, MRP-1/CD9 and KAI1/CD82 status was found to be the most significant.
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PMID:Transmembrane 4 superfamily as a prognostic factor in pancreatic cancer. 976 Nov 21

Telomerase, a specialized RNA-directed DNA polymerase that extends telomeres of eukaryotic chromosomes, is repressed in human somatic tissues and becomes activated during tumor progression in most human cancers. To date, little is known about how telomerase is activated and controlled in cancer, although activation is thought to be involved in cancer cell immortalization. Here, we report that human telomerase-associated protein 1 (hTEP1) and the telomerase catalytic subunit (human telomerase reverse transcriptase (hTERT)) are phosphoproteins and that their phosphorylation is a prerequisite for the activation of telomerase in intact human breast cancer cells. Identified by hTEP1 peptide affinity chromatography, protein kinase Calpha mediates the phosphorylation of hTEP1 and hTERT and induces a marked increase in telomerase activity. Thus, phosphorylation of hTEP1 and hTERT by protein kinase Calpha represents an essential step in the generation of a functional telomerase complex in the initiation and maintenance of telomerase activity in human cancer.
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PMID:Telomerase is controlled by protein kinase Calpha in human breast cancer cells. 983 21

Protein tyrosine kinases (PTKs) are a major class of proto-oncogenes that are involved in tumor progression. The purpose of this study was to establish a comprehensive PTK expression profile in gastric cancers, with the objective of identifying possible biomarkers for gastric cancer progression. We have designed degenerate primers according to the consensus catalytic motifs to amplify PTK molecules from gastric cancers by reverse transcriptase-PCR methods. The PTK expression profile was established by sequencing analysis of the cloned PCR products. We have identified 17 PTKs from a gastric adenocarcinoma. Two receptor PTKs, tie-1 and axl, were selected for in situ immunohistochemistry studies because of their higher expression level and their described roles in adhesion, invasion, and angiogenesis. Among the 97 gastric adenocarcinoma tissues examined, we observed positive immunohistochemical staining of tie-1 PTK in 69 and positive staining of axl kinase in 71 tissues. Statistical analysis with clinicopathological features indicates that tie-1 kinase expression is inversely correlated with patients' survival, whereas axl fails to show similar clinical significance. Our results illustrate the utility of tyrosine kinase gene family profiling in human gastric cancers and show that tie-1 tyrosine kinase may serve as a novel independent prognostic marker for gastric adenocarcinoma patients.
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PMID:tie-1 protein tyrosine kinase: a novel independent prognostic marker for gastric cancer. 1043 78

Hepatitis C virus (HCV) is pathogenetically involved in many cases of hepatocellular carcinoma (HCC) worldwide. HCV-related HCC is on the rise in many developed countries as a consequence of past infections with HCV. The time lag between HCV infection and cancer development is several decades. HCV-related tumors arise in older patients, are almost invariably associated with cirrhosis, and often have a less aggressive course than HCC related to other etiologic factors. In most patients, HCC grows as a single hepatic node for years before generating satellite or distant tumor nodes. However, there are tumors that originate as multifocal disease. Tumor progression and hepatic failure are the leading causes of death in most patients. HCV has been almost invariably detected in tumor tissue of anti-HCV patients with HCV, but it is not clear whether the virus promotes cancer through chronic hepatocellular inflammation, which is per se an important risk factor for HCC, or has a direct role in liver carcinogenesis. No reverse transcriptase activity has been found in infected livers, but there are data suggesting that HCV has oncogenic properties, because its interacts with cellular genes regulating cell growth and differentiation.
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PMID:Hepatitis C virus and hepatocellular carcinoma. 1051 6

Proopiomelanocortin (POMC) is a 31 kDa prohormone that is processed to various bioactive peptides, including adrenocorticotropin (ACTH), melanotropins (alpha, beta, gamma-MSH), lipotropins, and endorphins. POMC is expressed not only in the pituitary gland but also in a variety of nonpituitary organs and tumors, including melanomas. We previously showed that normal human melanocytes produce and secrete alpha-MSH and ACTH, and furthermore, that advanced melanoma cells generally produce higher amounts of POMC peptides that correlate with tumor progression. To elucidate the mechanism of this upregulation, the expression of genes encoding corticotropin-releasing hormone (CRH) and its receptor, CRH-R, as well as POMC and the MSH receptor (MC1-R), was evaluated by reverse transcriptase-polymerase chain reaction using cultured human melanoma cells, nevus cells, and normal melanocytes. Our results show that all melanocytic cells express CRH, CRH-R, POMC, and MC1-R, with highest intensities in melanoma cells. Furthermore, immunohistochemistry shows that CRH as well as POMC is strongly expressed in advanced melanomas, such as vertically growing lesions of acral lentiginous, nodular and metastatic melanomas, in contrast to negative expression in nevus cells. These results indicate that tumor progression accentuates CRH, CRH-R, and POMC expression by melanoma cells.
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PMID:Expression of proopiomelanocortin, corticotropin-releasing hormone (CRH), and CRH receptor in melanoma cells, nevus cells, and normal human melanocytes. 1053 83


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