Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The active exogenous murine leukemia virus sequences of mouse cells growing in culture are preferentially digested by deoxyribonuclease I in metaphase chromosomes. As determined by nuclear nick translation, all of the gene sequences of these cells active during interphase are in a deoxyribonuclease I-sensitive conformation during metaphase. This method of nick translation can therefore be used to label chromosomes in situ in order to visualize the active regions of the genome.
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PMID:Active genes are sensitive to deoxyribonuclease I during metaphase. 628 40

5'-Nucleotidase activity of normal human embryonic lung fibroblasts (IMR-90) was found to be inhibited by the homogenates of seven different cell lines originated from patients with different kinds of leukemia and of fresh lymphocytes from a patient with Sezary syndrome (circulating T-cell lymphoma). About 97% of the inhibiting activity was found in the soluble fraction of RPMI 8402 cells, a cell line originated from the lymphocytes of a patient with acute lymphocytic leukemia. This inhibiting activity was not destroyed by dialysis, heating at 56 degrees C for 30 min, nor digestion with RNAase or DNAase. About 85% of the inhibiting activity was destroyed by digestion with papain at 37 degrees C for 1 h and it was destroyed completely by heating at 100 degrees C for 30 min. When the heated (56 degrees C for 30 min) soluble fraction of RPMI 8402 cells was mixed with the homogenate of IMR-90 cells, it had no effect on the activities of alkaline, neutral or acid phosphatases, nor of N-acetyl-beta-D-glucosaminidase or cytochrome c oxidase of IMR-90 cells. Preincubating the mixed samples for 1, 20 and 45 min, respectively, before adding the substrate, the heated soluble fraction of RPMI 8402 cells did not increase the percentage of inhibition for 5'-nucleotidase of the homogenate of IMR-90 cells. No inhibition of other enzyme activities was observed under similar conditions. These data suggest that the inhibiting activity is due to a protein(s) that is not a protease. The inhibiting activity was found in a single peak after the soluble fraction was fractionated by Sephadex G-100 chromatography and sedimentation centrifugation. The molecular weight of the inhibitor was found to be approx. 35,000 by comparing its retention volume and sedimentation rate with those of proteins of known molecular weight. The present study suggest that the previously reported undetectability of 5'-nucleotidase in permanent cell lines could be due to the presence of a protein inhibitor for 5'-nucleotidase in these human leukemic cell lines. It also supports the hypothesis that the increased 5'-nucleotidase activity in normal senescent cells in vitro may be a control in cellular aging that is missing from leukemic cells in vitro.
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PMID:Implications of a 5'-nucleotidase inhibitor in human leukemic cells for cellular aging and cancer. 630 89

Xenoantisera were raised to total chromatin from the leukemia cell line K562, or materials released through limited deoxyribonuclease I digestion of nuclei or during the control incubation of nuclei without enzyme. The peroxidase-antiperoxidase method of antibody-antigen detection was employed to visualize individual antigens resolved on one-dimensional polyacrylamide gels following transfer to sheets of nitrocellulose (immunotransfers). Each antiserum contained multiple antigen specificities as evidenced by the diverse patterns of reactive bands displayed on the immunotransfers. The most striking difference in antigens recognized between the antisera was observed in the molecular weight region below 50,000, where two highly reactive bands were seen mainly with antiserum to nuclear materials released by deoxyribonuclease I digestion. The antigens detected with all of the antisera were present in chromatins prepared from proliferating cells, while the levels of antigens present in chromatin from non-proliferating peripheral blood lymphocytes were greatly reduced or not detected. Antigens in chromatin from proliferating cells that migrated with apparent molecular weights of 37,000 and 100,000 were not lost once the activities to antigens in lymphocyte chromatin were absorbed out. These two activities were absorbed from antisera with the same amount of chromatins from proliferating cells. Two antigens migrating at molecular weight 52,000 and 76,000 appeared more active in the chromatin from unstimulated lymphocytes than in chromatin from proliferating cells.
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PMID:Antigens in chromatin associated with proliferating and nonproliferating cells. 665 91

Glucocorticoid-specific binding macromolecules were measured and characterized in L2C cells, a B-lymphocyte guinea pig leukemia that is resistant to administered cortisol or adrenocorticotrophic hormone. L2C cells were harvested by cardiac puncture followed by Ficoll:Hypaque separation techniques. The cells were lysed by sonication, and the cytosol was obtained after centrifugation at 106,000 x g for 60 min at 0 degrees. Cytosol glucocorticoid receptor measurements were obtained by hydroxylapatite assay or column chromatography using Sephadex G-25. Maximal specifically bound [3H]triamcinolone acetonide in the cytosol fraction was 300 fmol/10(8) cells. Scatchard plot of specific L2C cytosol binding gave a Kd of 18 nM and an estimate of 2000 binding sites/cell. The specificity of binding in L2C cytosol was triamcinolone acetonide > dexamethasone > cortisol > progesterone > testosterone = estradiol. Binding of [3H]triamcinolone acetonide to cytosol glucocorticoid receptors was maximal at 22 hr of incubation at 19 degrees, and the receptor complex was stable for 48 hr. The receptor complex was not affected by DNase or RNase, but the receptor complex was lost with pronase or heat denaturation. Whole-cell binding assays were also performed, which resulted in similar quantities of maximally bound glucocorticoid receptor as well as the specificity of binding of various hormone analogs as found in the cytosol receptor assays. Transferring the whole cells from 0 to 22 degrees resulted in the appearance in nuclei of approximately 65% bound receptors. However, these translocated receptor complexes do not appear to affect the viability of the L2C cells as measured by trypan blue exclusion.
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PMID:Characterization of glucocorticoid-specific binding in the L2C leukemia. 693 47

Early detection of testicular leukaemia and the identification of residual leukaemic cells in treated patients are important aims in the management of males with acute lymphoblastic leukaemia (ALL). In most cases of ALL ( greater than 95%) the blast cells express terminal deoxynucleotidyl transferase (TdT), a nuclear enzyme. We have therefore standardized the immuno-fluorescence and -peroxidase techniques (using anti-Tdt antibodies) for identifying TdT cells in the normal thymus, as well as in samples of testis with heavy leukaemic infiltrates (positive controls). TdT cells can be identified in formalin (but not in Bouin's or Carnoy's) fixed paraffin-embedded tissues, and the preservation of morphological details is excellent. The method is nevertheless difficult to standardize and also requires the use of deoxyribonuclease (DNase) for the digestion of sections. However, in frozen tissue sections, stronger staining of TdT cells was found, even without DNase treatment. Good morphology was preserved when cut sections were fixed immediately in the cryostat. In the second part of the study 15 samples from treated boys were analysed to see whether the technique is suitable to identify residual minimal leukaemic infiltrates. In 5 patients scanty disseminated TdT cells were detected, and in 2 patients small clumps of TdT cells were seen. The results indicate that the immunohistological identification of TdT ALL blasts may be the method of choice.
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PMID:Nuclear terminal deoxynucleotidyl transferase in leukaemic infiltrates of testicular tissue. 704 2

The binding of [3H]dexamethasone to the cytosol fraction prepared from the human leukemia cell line K562 was studied with a competitive binding assay. Specific, saturable binding was identified by incubating cytosol with increasing concentrations of [3H]dexamethasone in the presence and absence of nonlabeled dexamethasone. A Scatchard plot of the data was linear, suggesting the presence of a single class of binding sites with KD = 2.49 +/- 0.23 x 10(-8)M. The binding sites appear to be protein in nature, since specific binding was reduced by treatment of the cytosol with trypsin, pronase, and heat; neither DNase nor RNase affected the binding. Binding was also reduced in the absence of alpha-thioglycerol and in the presence of p-chloromercuribenzoate and N-ethylamaleimide, suggesting that optimal binding activity requires reduced sulfhydryl groups. The binding site appears to be specific for glucocorticoids as evaluated in competition studies. Finally, glucocorticoids were found to inhibit the clonal growth of K562 cells in vitro, suggesting a potential role for glucocorticoid binding sites in the modulation of K562 cell proliferation.
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PMID:Identification of a glucocorticoid receptor in the human leukemia cell line K562. 720 98

Activity of the lysosomal hydrolases DNAase II, acid RNAase and acid phosphatase was studied in the mouse liver and spleen under developing Friend's viral leukemia. The activity of DNAase II in the liver was considerably increased from the 12th day after inoculation of virus-containing material and reached the maximum by the 20th day of the experiment. The activity of acid phosphatase was changed insignificantly while that of acid RNAase showed no deviations from the control level. A possible role of the lysosomal hydrolases in leukemia development is discussed.
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PMID:[Lysosomal hydrolase activity during development of experimental leukemia]. 739 62

Mouse leukaemia inhibitory factor (LIF) is a polyfunctional cytokine which exhibits multiple functions in vitro and in vivo. Two forms of LIF cDNA, differing at their 5' ends, have been described encoding either diffusible (D-LIF) or matrix-associated (M-LIF) forms of the protein [Rathjen, Toth, Willis, Heath and Smith (1990) (Cell 62, 1105-1114]. The present report describes the DNA sequence and functional characterization of the murine LIF gene and its surrounding transcriptional regulatory elements. Transient transfection of constructs containing the LIF gene and various amounts of 5'-non-coding sequence failed to give detectable levels of expression, suggesting the presence of inhibitory sequences within the LIF gene. Stable cell lines were produced by transfection of experimental constructs containing various lengths of 5'-non-coding sequence of the LIF gene, or the heterologous phosphoglycerate kinase promoter, linked to an LIF/neomycin-resistance-hybrid-coding sequence. The frequency of recovery of stable clones indicated that sequences located in the first intron between the transcriptional start sites for D-LIF and M-LIF act to suppress expression of the gene in most genomic locations. This region is rich in GC residues and has been shown to be hypomethylated in vitro [Kaspar, Dvorak and Bartunek (1993) FEBS Lett. 319, 159-162]. Analysis of the LIF/neomycin-resistance transgene expression in these stable cell clones demonstrated that transcripts containing the M-LIF or D-LIF exons required the presence of sequences located between -1200 and -3200 in the LIF gene. In the absence of these sequences, transcription is initiated elsewhere within the first intron. These sequences can be replaced by the heterologous phosphoglycerate kinase promoter. Deletion of the GC-rich region between the D-LIF and M-LIF transcriptional start sites results in the appearance of transcripts that do not splice out the first intron of the LIF gene. These may result from gene or promoter trapping of the LIF gene. Sequence analysis of the region between -1200 and -3200 revealed a number of minimal steroid-response elements, regions of similarity to DNAase I-hypersensitive sites in the uteroglobin gene and a region of alternating purine/pyrimidine sequence. This study therefore defines two important regulatory regions in the LIF gene: a GC-rich region in the first intron and a distal 'enhancer' located between -3200 and -1200.
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PMID:Identification of two elements involved in regulating expression of the murine leukaemia inhibitory factor gene. 752 Jun 92

Programmed cell death is activated, by different stimuli and in many cell types, to regulate cell population balance during tissue proliferation and embryogenesis. Its initial event seems to be, in most cases, the activation of a Ca(2+)-dependent endonuclease, causing DNA cleavage into nucleosomic fragments. Its morphological expression is characterized by deep nuclear changes, consisting of typical cap-shaped chromatin marginations, followed by nuclear fragmentation and final formation of numerous micronuclei. Cytoplasmic damage appears in a very late stage of the process and the greatest part of the phenomenon appears to take place despite good preservation of the plasma membrane and organellar component. In the present study we analyzed apoptosis in camptothecin-treated HL60 leukaemia cells, and in freshly isolated mouse thymocytes treated with dexamethasone. The process was first quantified and time monitored by flow cytometry. Subsequently the specimens were processed for morphological examination in order to investigate the behaviour of the different nuclear domains. To follow DNA and RNA localization, we utilized osmium ammine and DNase-colloidal gold cytochemical reactions. The concentration of most DNA in the cap-shaped structures was demonstrated by these reactions. Confocal microscopy of cells processed by in situ nick-translation suggested that DNA was firstly cleaved and subsequently condensed in cup-shaped structures. Despite the strong nuclear modifications, nucleoli could be clearly recognized until the late apoptotic stages.
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PMID:The behaviour of nuclear domains in the course of apoptosis. 786 64

To characterize the interactions between human T-cell leukemia virus (HTLV) infection and cellular gene expression, we examined the expression of the lymphokine interleukin 3 (IL-3) in the presence and absence of HTLV infection. IL-3, like granulocyte-macrophage colony-stimulating factor (GM-CSF), is produced by activated but not resting T cells, but although GM-CSF is constitutively expressed in HTLV-infected T cells IL-3 mRNA cannot be detected in either unstimulated or mitogen-stimulated HTLV-infected cells by polymerase chain reaction (PCR) analysis. In contrast, transient co-transfection studies with an IL-3 promoter-CAT reporter gene and an HTLV-II Tax expression construct demonstrate that Tax can transactivate the IL-3 promoter in HTLV-uninfected T cells. To determine whether differences in IL-3 promoter-binding proteins present in HTLV-infected and uninfected T cells account for this discrepancy, DNAase I footprinting of the IL-3 promoter was performed. Although crude nuclear extracts from both cell types protected the IL-3 sequences located between base pairs -168 and -125, the sequences between -125 and -103, which contain the lymphokine consensus sequences CK-1 and CK-2, were protected by extracts from HTLV-infected but not HTLV-uninfected T cells. Deletion of the region containing the CK-1 and CK-2 sequences from an IL-3 promoter CAT construct resulted in a sixfold rise in promoter activity in HTLV-infected but not uninfected T-cell lines, indicating that this region participates in the repression of IL-3 gene expression in HTLV-infected T cells.
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PMID:Differential effect of HTLV infection and HTLV Tax on interleukin 3 expression. 851 Sep 34


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