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:2.7.7.7 (DNA polymerase)
17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rational design of antitumor and antiviral agents must ultimately take advantage of biochemical differences between normal host cells and transformed cells. The initial experiments must be performed with subcellular or cellular model systems. For the studies with arabinosyl nucleosides we have chosen those enzyme systems, synthesizing DNA and RNA; being precursor analogues, the different arabinosyl nucleosides have been added in the triphosphate state to the different DNA- and RNA polymerase assays. 1-beta-D-Arabinofuranosylcytosine-5'-triphosphate has been found to inhibit the RNA-dependent DNA polymerases (isolated from oncogenic RNA viruses) 200-fold more sensitively than viral and cellular DNA-dependent DNA polymerases. Recent results, showing that RNA-leukemia-virus-related sequences are present in DNA of some human leukemia patients might support the assumption that the efficacy of this antimetabolite in the treatment of acute leukemia is due to its, at least relative selective inhibitory activity on reverse transcriptase. 9-beta-D-Arabinofuranosyladenine-5'-triphosphate is a strong inhibitor of cellular DNA polymerases with the cytological consequence of an inhibition of cell proliferation. The clinical benefit of the compound in treatment of tumors is dependent on their levels of adenosine deaminase. The triphosphate of this compound is a 100-fold more sensitive inhibitor of the herpesvirus DNA polymerase compared to the cellular replicative DNA polymerase. In addition the analogue, incorporated into herpesvirus DNA, acts as chain terminator. These effects are the biochemical basis for the highly selective antiherpesvirus activity of this antimetabolite. The anomer 9-alpha-D-arabinofuranosyladenine-5'-triphosphate only inhibits cellular replicative DNA polymerase and has no effect on herpesvirus DNA polymerase. Consequently this agent acts only cytostatically and not antivirally. Concerning 1-beta-D-arabinofuranosyluracil and 1-beta-D-arabinofuranosylthymine no pronounced antitumor or antiviral effect is known.
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PMID:Rational design of arabinosyl nucleosides as antitumor and antiviral agents. 61 2

Proliferative cell fractions were measured by flow cytometry in 20 patients with acute leukemia, 4 with chronic myelocytic leukemia in blastic crisis and 7 with malignant lymphoma. The cells were fixed with 2% paraformaldehyde followed by staining with fluorescein isothiocyanate conjugated monoclonal antibody against DNA polymerase a. The DNA polymerase a-positive population was widely distributed in leukemia, from 20.4% to 84.7% in peripheral blood and from 6.5% to 92.5% in the bone marrow. A positive correlation was found between the values in peripheral blood and bone marrow. The values ranged from 66.4% to 88.1% in cells from cases of malignant lymphoma. Cryopreserved cells may be available for measurement of DNA polymerase a because the result obtained in both frozen and fresh cells were essentially the same.
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PMID:[Detection of proliferative cells by DNA polymerase a as a proliferation associated marker]. 144 3

Chronic myelogenous leukemia (CML) is a stem cell disease which, on a clinical level, progresses from the release from growth control of normally differentiated cells (a preleukemic state) to an acute leukemia. On a molecular level, the evolution of CML to acute leukemia is a multistep process. We propose that an early step, at the stem cell level, is acquisition of the ability for gene movement, which allows subsequent submicroscopic and chromosomal rearrangements that cause changes in the growth characteristics and regulation of the stem cell. A specific platelet DNA polymerase (PDP - reverse transcriptase) may play a role in gene movement. The characteristic reciprocal translocation of chromosomes #9 and #22, causing the activation of the c-abl oncogene, appears to be responsible for the uncontrolled cellular growth. Yet, other growth factors (e.g., platelet derived growth factor) and activated oncogenes (e.g., c-sis) must be responsible for the stimulation, progression, and variability seen during the course of the disease. Because CML is a progressive disease with clinically definable stages, CML appears to be a model system for the study of the molecular basis of the progression of preleukemia to leukemia specifically, and preneoplasia to aggressive neoplasia in general.
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PMID:Implications of retroviral and oncogene activity in chronic myelogenous leukemia. 243 4

Pirarubicin (THP-adriamycin or THP-doxorubicin) was found during a search of new anthracycline antibiotics among 4'-O-substituted compounds having less toxicities than other anthracycline anticancer drugs in 1979 by Umezawa et al. In its preclinical studies, this compound possessed almost similar antitumor efficacies to doxorubicin, but was effective against doxorubicin-resistant P388 and other murine tumor cell lines. This compound was rapidly incorporated into tumor cells, inhibiting DNA polymerase alpha and subsequently DNA synthesis. Inhibition of RNA synthesis was also noted. In the clinical studies, clinical responses were established against head and neck cancer, breast cancer, urogenital cancers, ovarian cancer, uterine cancer, acute leukemia, and malignant lymphoma, showing a wide antitumor spectrum clinically. Among the side effects, cardiac toxicity, alopecia and disturbance of the digestive organs were mild. From these results, THP-adriamycin seems to be a useful clinical drug for human solid tumors.
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PMID:[Pirarubicin (THP-adriamycin)]. 304 96

Chicken myeloblasts transformed by avian myeloblastosis virus (AMV) in the absence of nondefective helper virus (termed nonproducer cells) were found to release a defective virus particle (DVP) that contains avian tumor viral gag proteins but lacks envelope glycoprotein and a DNA polymerase. Nonproducer cells contain a Pr76 gag precursor protein and also a protein that is indistinguishable from the Pr180 gag-pol protein of nondefective viruses. The RNA of the DVP is 7.5 kilobases (kb) long and is 0.7 kb shorter than the 8.2-kb RNAs of the helper viruses of AMV, MAV-1 and MAV-2. Comparisons based on RNA.cDNA hybridization and mapping of RNase T1-resistant oligonucleotides indicated that DVP RNA shares with MAV RNAs nearly isogenic 5'-terminal gag and pol-related sequences of 5.3 kb and a 3'-terminal c-region of 0.7 kb that is different from that found in other avian tumor viruses. Adjacent to the c-region, DVP RNA contains a contiguous specific sequence of 1.5 kb defined by 14 specific oligonucleotides. Except for two of these oligonucleotides that map at its 5' end, this sequence is unrelated to any sequences of nondefective avian tumor viruses of four different envelope subgroups as well as to the specific sequences of fibroblast-transforming avian acute leukemia and sarcoma viruses of four different RNA subgroups. The specific sequence of the DVP RNA is present in infectious stocks of AMV from this and other laboratories in an AMV-transformed myeloblast line from another laboratory, and it is about 70% related to nucleotide sequences of E26 virus, an independent isolate of an AMV-like virus. Preliminary experiments show DVP to be leukemogenic if fused into susceptible cells in the presence of helper virus. We conclude that DVP RNA is the leukemogenic component of infectious AMV and that its specific sequence, termed AMV, may carry genetic information for oncogenicity. Thus we have found here a transformation-specific RNA sequence, unrelated to helper virus, in a highly oncogenic virus that does not transform fibroblasts.
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PMID:Genetic structure of avian myeloblastosis virus, released from transformed myeloblasts as a defective virus particle. 615 39

Two virus-specific RNA species of 7.5 and 7.0 kilobases have been identified in avian myeloblastosis virus (AMV) by denaturing gel electrophoresis and blot hybridization analysis, and they were found to be in a 10:1 ratio. The individual RNAs direccted the cell-free synthesis of the 76,000-dalton "gag" protein and the 180,000-dalton "gal-pol" protein, thereby demonstrating 5' sequence homology of approximately 4.9 kilobases between the two species. Synthesis of these two precursor proteins by the AMV genome indicates structural differences between AMV and other avian acute leukemia viruses. The two viral RNAs were transcribed into complete cDNA copies with AMV DNA polymerase. Linear proviruses were found to be 90--100% resistant to S1 nuclease. Analysis of single-stranded transcripts demonstrated two distinct species of 2.6 and 2.3 x 10(6) daltons, and analysis of duplexes formed from the single-stranded transcripts demonstrated species of 5.2 and 4.0 x 10(6) daltons.
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PMID:Analysis of avian myeloblastosis viral RNA and in vitro synthesis of proviral DNA. 626 60

Blast cells in acute leukemia and lymphoma appear to be "frozen" at various stages of lymphoid cell differentiation. The enzymatic and antigenic phenotypes expressed by these cells often correspond to the gene products of their normal precursors. We have used various immunocytochemical and enzymatic techniques to identify membrane, nuclear, and cytoplasmic markers associated with the prolactin-dependent Nb2 lymphoma cell line. The Nb2 cells, whether stationary or in log-phase growth, did not express any surface immunoglobulin. However, 100% of the Nb2 cells bound both a monoclonal antibody raised to rat thymocyte W3/25-HLK, which specifically binds an antigenic determinant on rat T-helper cells, and second monoclonal antibody OX8-HL, which identifies rat nonhelper T-cells. Transmission electron microscopy showed no evidence of phagocytic vacuoles, and activity of the lysosomal enzyme muramidase was also absent. There was no evidence of the DNA polymerase enzyme terminal deoxynucleotidyl transferase. alpha-Naphthyl acetate esterase activity was indicated in about 50% of the Nb2 cells by a faint particulate cytoplasmic staining similar to that found in thymocytes. Rosette formation with guinea pig erythrocytes, a property of mature rat thymocytes, was not observed with Nb2 cells. The data suggest that the Nb2 tumor may have arisen from a thymocyte at an intermediate stage of differentiation. The presence of Thy-like alpha-naphthyl acetate esterase pattern and the binding of both W3/25-HLK and OX8-HL support the thymic origin and relative immaturity of these lymphoid cells. It is becoming increasingly apparent that a significant proportion of lymphomas and leukemias also originate in undifferentiated thymic cels.
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PMID:Thymic origin of the prolactin-dependent Nb2 lymphoma cell line. 704 17

We studied the proliferative activity of leukemic cells obtained from the peripheral blood and bone marrow of 34 patients; 30 with acute leukemia and 4 with chronic myelogenous leukemia in blastic crisis. Flow cytometry was performed using monoclonal antibody against DNA polymerase alpha. Since fresh and frozen cells showed virtually identical DNA polymerase alpha-positive populations and flow cytometric histograms, 52 cryopreserved samples (25 from peripheral blood and 27 from bone marrow) were used in this study. The DNA polymerase alpha-positive population ranged from 20.4% to 84.7% in peripheral blood, and from 6.5% to 92.1% in bone marrow. A positive correlation (r = 0.76, P < 0.01) was found between DNA polymerase alpha-positive populations in peripheral blood and bone marrow from the same patient. This suggests that the DNA polymerase alpha-positive population in the bone marrow can be estimated from that in peripheral blood. No relationship was observed between the positive population and the response to chemotherapy. Statistical analyses for all cases showed no relationship between the DNA polymerase alpha-positive population and either the tumor cell count or time to reach a nadir. However, a negative correlation was observed between the positive population in bone marrow samples and the time to reach a nadir (r = -0.64, P < 0.05) in those patients who achieved a complete response. In addition, in the cases of acute non-lymphocytic leukemia who did not respond to chemotherapy, a positive correlation was observed between the tumor cell count in bone marrow and the DNA polymerase alpha-positive population (r = 0.93, P < 0.01). Thus, the method described here provides a simple and time-efficient means of detecting the proliferative activity of leukemic cells, which is a useful parameter in the treatment of leukemia.
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PMID:Flow cytometric detection of proliferative cells in leukemias. 814 1

To characterize a new anthracycline agent, idarubicin (4-demethoxydaunorubicin) and to establish its reasonable and appropriate use in the chemotherapy of acute leukemia, we examined its mode of action and compared it with the results obtained for daunorubicin. Idarubicin was shown to have the characteristic features of the action mechanism of anthracyclines, such as having a strong binding capacity to DNA, in terms of frequency and efficiency and reducing the template activity of DNA by binding to DNA or inducing DNA strand breaks in leukemic cells and inhibiting the DNA polymerase reaction. Idarubicin was superior to daunorubicin in terms of intracellular accumulation and binding capacity to DNA, which may result in idarubicin having much stronger activity in inducing DNA strand breaks than daunorubicin. These excellent properties of idarubicin were considered to explain idarubicin having stronger antileukemic effects than daunorubicin. The efficacy of idarubicin in multidrug-resistant cells is also discussed.
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PMID:Action mechanism of idarubicin (4-demethoxydaunorubicin) as compared with daunorubicin in leukemic cells. 849 91

Fifty-nine patients with acute leukemia were studied by flow cytometry using monoclonal antibody against DNA polymerase alpha. Since fresh and frozen cells showed identical flow cytometric histograms, 86 cryopreserved samples (39 from peripheral blood and 47 from bone marrow) were used in this study. The DNA polymerase alpha-positive population ranged from 16.3 to 84.7% in peripheral blood, and from 6.5 to 92.1% in bone marrow. A positive correlation (r = 0.80; p < 0.01) was found between DNA polymerase alpha-positive populations in peripheral blood and bone marrow from the same patient. This suggests that the DNA polymerase alpha-positive population in the bone marrow can be estimated from that in peripheral blood. A negative correlation was observed between the positive population in bone marrow samples and the time to reach a nadir (r = -0.58: p < 0.01), while a positive correlation was found between the tumor cell count in bone marrow and the DNA polymerase alpha-positive population (r = 0.64; p < 0.01) in patients who responded to chemotherapy.
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PMID:Cell proliferation detected by DNA polymerase alpha in acute leukemias. 904 64


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