Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

RNA biosynthesis catalyzed with DNA-dependent RNA polymerase was demonstrated in the reconstructed system containing isolated lymphocyte nuclei, Mg2+ or Mn2+ salts, ammonium sulphate, in the presence of four nucleosidetriphosphates. Both the Mg2+ and Mn2+-dependent forms of this enzyme were revealed in the nuclei of normal lymphocytes and those of patients suffering from melanoma, carcinoma of the lung and sarcoma. The activities of both forms of RNA-polymerase were greater in the nuclei of the lymphocytes from sick individuals than in the normal analogues. DNA-dependent RNA-polymerase sensitivity to dexamethasone and PHA of the nuclei of lymphocytes obtained from patients with carcinoma of the lung, melanoma, and sarcoma was decreased in comparison with the normal.
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PMID:[Sensitivity of the lymphocyte RNA-synthesizing system of patients with different malignant neoplasms to phytohemagglutinin and dexamethasone]. 85 72

L-Glutamic acid (gamma-4'-hydroxyanilide) (GHB) is oxidized by tyrosinase to a quinone which inhibits DNA polymerase, RNA polymerase, and mitochondrial energy production within mushrooms. It was previously shown that GHB can kill B16 melanoma cells in culture, but lacks cytotoxicity for nontyrosinase-containing cells. We have conjugated this drug to a superpotent melanotropic peptide and examined the bioactivity of this conjugate to melanoma cells. 4'-Hydroxyaniline was attached to glutamic acid at position 5 in the superpotent melanotropin fragment analogue, Ac-[Nle4, D-Phe7]alpha-MSH4-10-NH2. The melanotropin:anilide conjugate, Ac-[Nle4, Glu(gamma-4'-hydroxyanilide)5, D-Phe7]alpha-MSH4-10-NH2, was not cytotoxic to B16 or Cloudman S91 mouse melanoma cells in culture, as determined by cell counts and protein assays. Interestingly, we also found that GHB stimulated melanoma cell tyrosinase above control levels in both melanoma cell lines. In our study, GHB itself also was found not to be cytotoxic to B16 or S91 melanoma cells in culture. In the frog skin bioassay, the melanotropin conjugate was more potent than alpha-MSH or Ac-[Nle4, D-Phe7]alpha-MSH4-10 in stimulating melanosome dispersion. These results demonstrate that putative chemotherapeutic ligands can be incorporated into active-site fragment analogues of MSH without loss of biological activity.
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PMID:Synthesis and actions of a melanotropin conjugate, Ac-[Nle4, Glu(gamma-4'-hydroxyanilide)5, D-Phe7]alpha-MSH4-10-NH2, on melanocytes and melanoma cells in vitro. 216 79

The antimalarial agent chloroquine (CQ) inhibits DNA and RNA polymerase and interferes with lysosomal function. We sought to determine if these properties make chloroquine effective as a hyperthermia sensitizer. B16F10 melanoma cells were treated for 180 min at 37 or 41 degrees C with 0.005 mM CQ, 0.01 mM CQ, 0.05 mM CQ, or 0.1 mM CQ and colony formation evaluated at 7 days. CQ was cytotoxic at 37 or 41 degrees C in a dose-dependent fashion. A significant increase in cytotoxicity was seen with 0.5 and 0.1 mM CQ at 41 degrees C compared to 37 degrees C (P less than 0.01). The influence of treatment time on CQ cytotoxicity was examined by treating cells with 0.05 mM CQ at 37 or 41 degrees C for 30-min intervals from 30 to 180 min. Increasing length of exposure to CQ increased cytotoxicity at both 37 and 41 degrees C. For each interval studied treatment at 41 degrees C significantly decreased colony formation compared to treatment at 37 degrees C (P less than 0.01). Complete cell kill was achieved after 180 min of 41 degrees C treatment compared to 80% cell kill at 37 degrees C. We conclude that in this model CQ is an effective potentiator of hyperthermia.
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PMID:Chloroquine as a hyperthermia potentiator. 273 23

We describe the construction of a recombinant DNA plasmid, consisting of the vector pBR322 and full-length tissue-type plasminogen-activator (t-PA) cDNA, by using polyadenylated RNA from cultured Bowes melanoma cells as substrate. A 1280-base-pair PstI restriction fragment, covering the 3' untranslated region and part of the coding region for the t-PA L-chain, was used as a radiolabelled probe to determine the size and the number of t-PA mRNA molecules in cultured endothelial cells of different origin from the same individual. Northern blotting showed that in all these cells a t-PA mRNA is synthesized of about 2500 nucleotides, indicating that transcriptional initiation, splicing and polyadenylation is similar. The number of t-PA mRNA molecules per cell measured, by using a dot-blotting technique and t-PA mRNA made in vitro, with a plasmid DNA preparation harbouring a specific promotor of the Salmonella typhimurium bacteriophage SP6, t-PA cDNA and SP6 RNA polymerase as standard, is approx. 10,000 in all cultured endothelial cells from adult vessels. However, the amount of t-PA antigen synthesized and/or secreted differs by a factor of 6-20. Relatively large amounts of t-PA antigen secreted were detected in conditioned medium from vena-cava-derived cells, whereas low amounts were found in conditioned medium from arteria-iliaca-derived cells.
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PMID:Quantification of tissue-type plasminogen activator (t-PA) mRNA in human endothelial-cell cultures by hybridization with a t-PA cDNA probe. 309 Oct 7

Macbecin I showed marked antitumor activity against intraperitoneally (ip) inoculated leukemia P388, melanoma B16, and Ehrlich carcinoma in mice on ip administration. The maximum effect measured in terms of ILS% (increase of life span) was 97 at a daily dose level of 10 mg/kg for leukemia P388, 103 at 5 mg/kg for melanoma B16, and 206 at 10 mg/kg for Ehrlich carcinoma. The effect of macbecin I on leukemia L1210 was slight (39 ILS%) and no activity was observed against leukemia L5178Y or P388/P-3 (a line of P388 resistant to ansamitocin P-3), or MOPC-104E myloma. Three to six hours after administration of 0.5 mg/kg or more of macbecin I to mice bearing ascites leukemia P388 cells, typical karyorrhexis followed by cytolysis in P388 cells was observed. Cytocidal changes induced by macbecin I were also observed in cells which were temporarily prevented from entering mitosis by treatment with known antitumor agents such as 5-fluorouracil, cyclophosphamide, and neocarzinostatin, whereas such cytolysis was not observed in cells which were arrested in metaphase by treatment with ansamitocin P-3. Cytotoxicity of macbecin I to cultured KB cells was observed at doses of 10(-1) micrograms/ml and more. Reverse transcriptase and terminal deoxynucleotidyl transferase activities were not inhibited by macbecin I.
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PMID:Antitumor and cytocidal activities of a newly isolated benzenoid ansamycin, macbecin I. 618 64

Peptides of melanosomal proteins have recently been shown to be recognized in an HLA-restricted mode by specific cytolytic T lymphocytes in melanoma patients. Dendritic antigen-presenting cells (DC) are considered to be the most effective stimulators of T cell responses, and the use of these cells has therefore been proposed to generate therapeutic responses to tumor antigens in cancer patients. We, therefore, generated DC from peripheral blood of normal donors in the presence of granulocyte/macrophage colony-stimulating factor and interleukin-4. Flow cytometric analysis of the cells during a 2-week culture revealed a loss of CD14 and CD34 expression, a concomittent increase of CD1a, CD11a,b and c, CD44, CD45, CD54, HLA-class I and II, and intermediate levels of CD26, CD80 and CD86. Cultured DC stimulated proliferation of allogeneic T cells and induced a marked, up to 20-fold, stimulation of T cell proliferation after pulsing with tetanus toxoid. To achieve independence of already-identified antigenic peptides presented in HLA class I-restricted fashion, which limits the general applicability of such peptides for vaccination of melanoma patients, we tested whether DC are transfectable with eukaryotic expression plasmids. DC transfected with two reporter genes (CAT, beta-galactosidase) using a liposome-based transfection technique, exhibited only low levels of enzymatically active proteins, but were able to degrade rapidly intracellular proteins and to process peptides efficiently. Chloramphenicol acetyltransferase as well as tyrosinase mRNA were detectable after transfection by reverse-transcriptase-polymerase chain reaction, and enzyme activities became measurable. Furthermore, DC transfected with the tyrosinase gene were able to induce specific T cell activation in vitro, indicating appropriate peptide processing and presentation in DC after transfection. These data suggest new approaches to future tumor vaccination strategies.
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PMID:Dendritic cells generated from peripheral blood transfected with human tyrosinase induce specific T cell activation. 748 49

Restriction of the T cell receptor repertoire suggesting ongoing specific immune mechanisms has recently been described in melanoma tissue by several groups of investigators. The functional relevance for immunotherapy of melanoma, however, has not been established. We studied the T cell receptor repertoire in two melanoma metastases of a patient with a mixed response to immunotherapy. Expression of T cell receptor V beta regions was determined by subgroup-specific semiquantitative RNA polymerase chain reaction (PCR). In the regressing skin lesion a restricted expression of the T cell receptor repertoire and overexpression of three V beta subgroup genes was found; no restriction was present in the simultaneously progressing skin lesion of the same patient, compared with peripheral blood lymphocytes. Comparison of T cell receptor V beta gene expression in two metastatic lesions of a patient with simultaneously growing skin metastases, who did not receive immunotherapy, revealed only minor differences. These observations show for the first time an association between restricted T cell receptor repertoire and responsiveness of melanoma to immunotherapy and suggest a role of T cells using the overexpressed V beta genes for the cytokine-induced tumour regression.
Melanoma Res 1995 Apr
PMID:Restriction of T cell receptor V beta repertoire in melanoma metastasis responding to immunotherapy. 762 Mar 41

The tyrosinase promoter has been used to target expression of the mutated human T24 Ha-ras oncogene in pigment-producing cells of transgenic mice. Two independent founder mice carrying the transgene survived and showed the same distinct phenotype of mutated coat color, deeply pigmented skin with multiple nevi, and twirling behavior. The offspring of one of these founders were developed into a line that stably expressed the same phenotype. Histopathological analysis of the tissues revealed hyperpigmentation and/or melanocytic hyperplasia in the skin, eyes, inner ear, and meningeal membranes in the brain. Reverse transcriptase-polymerase chain reaction analysis revealed expression of the transgene in skin, brain, and spleen. We propose that these transgenic mice will be a model for studying the process of multistage melanoma carcinogenesis and a system for evaluating potential chemopreventive agents.
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PMID:Hyperpigmentation and melanocytic hyperplasia in transgenic mice expressing the human T24 Ha-ras gene regulated by a mouse tyrosinase promoter. 766 20

The response of mouse T cells to the superantigen staphylococcal enterotoxin A (SEA) requires 1000-fold higher concentrations compared to human T cells. In order to develop a sensitive model for SEA studies in mice, the immunopharmacology has been studied in T-cell receptor (TcR) V beta 3 transgenic (TGV beta 3) and non-transgenic (non-TG) C57Bl/6 mice. The frequency of SEA-responsive T cells in the TGV beta 3 mice exceeded 90%, whereas a 10-fold lower frequency was seen in normal C57Bl/6 mice. Nanograms of SEA injected intravenously into TGV beta 3 mice induced strong cytolytic T lymphocyte (CTL) activity against SEA-coated major histocompatibility complex (MHC) class II+ B-lymphoma cells, whereas administration of 1000-fold higher amounts of SEA to non-TG littermates or normal C57Bl/6 mice induced only a moderate response. Kinetic analysis demonstrated that the CTL activity was more rapidly detectable in TG mice, but substantial levels were seen 2 days after SEA injection in both TGV beta 3 and non-TG mice. The cytotoxic T-cell response induced by SEA in TGV beta 3 and non-TG mice was completely MHC class II dependent, as SEA-coated MHC class II-transfected syngeneic B16 melanoma cells but not untransfected B16 cells were sensitive to lysis. Large amounts of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) accumulated in serum of TGV beta 3 mice after injection of 10 ng SEA, whereas only marginal amounts were recorded in non-TG even after injection of 100 micrograms SEA. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis demonstrated that SEA-induced TNF-alpha and IFN-gamma mRNA reached maximal levels 1 hr after SEA administration in TGV beta 3 mice, whereas peak serum levels of TNF-alpha and IFN-gamma proteins were recorded after 2 hr. Comparison of the mRNA levels of a panel of cytokines in the TGV beta 3 and non-TG mice revealed that almost similar amounts of interleukin-1 (IL-1) were induced in both strains, whereas IL-4 was only detected at significant levels in the TGV beta 3 mouse. The results suggest that TGV beta 3 mice are suitable for studying in vivo immune responses to superantigens at concentrations comparable to the potent effects elicited in humans. Moreover, this model is useful for detailed studies on the dynamic regulation of T-cell activation and anergy induced by superantigens.
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PMID:Immunopharmacology of the superantigen staphylococcal enterotoxin A in T-cell receptor V beta 3 transgenic mice. 769 31

In recent years, several studies have documented that melanoma cell lines produce various cytokine/growth factors and their receptors. Since cell lines can acquire altered properties, such as changes in growth requirements, we studied constitutive cytokine gene expression in melanoma cells from 20 fresh surgical specimens: seven primary melanomas and 13 metastases (12 lymph-node metastases and one subcutaneous metastasis). After tumour cell isolation by discontinuous gradient, we tested for mRNA expression by means of reverse-transcriptase polymerase chain reaction. Most melanoma cells tested expressed growth factors: basic fibroblast growth factor (bFGF), interleukin (IL)1 alpha, IL-1 beta, IL-6 and IL-8 and, in five cases out of 20, expressed granulocyte-macrophage colony-stimulating factor (GM-CSF) (two out of five were also positive for GM-CSF receptor). Our results do not point to a direct correlation between cytokine expression and clinical stage at the time when the bioptic specimen was obtained. However, they allow us to suggest a possible metastatic tumour cell phenotype, in which autogenous GM-CSF expression could modulate immune response against the tumour cell itself or could potentiate metastatic colonization properties.
Melanoma Res 1995 Feb
PMID:Cytokine expression in human primary and metastatic melanoma cells: analysis in fresh bioptic specimens. 773 55


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