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)

Adenosine deaminase (ADA) deficiency is associated with a fatal severe combined immunodeficiency. Because most patients do not have a suitable marrow donor, the introduction of a normal ADA gene into the patient's marrow cells is a potentially useful alternative therapy. To identify vectors that provide optimal gene expression in human hematopoietic cells, we investigated retroviral vectors containing the ADA gene under the transcriptional control of the promoter/enhancers of Moloney murine leukemia virus, the simian virus 40 early region, the cytomegalovirus immediate-early gene, the lymphotropic papovavirus, and the human beta-globin gene. ADA expression from these vectors was monitored in the ADA- human histiocytic lymphoma cell line DHL-9, and in the multipotential chronic myeloid leukemia cell line K562. ADA expression in infected K562 cells was also measured after induction of megakaryoblastic differentiation by phorbol ester, and after induction of erythroid differentiation by sodium n-butyrate or hemin. In these hematopoietic cell lines, the vectors that contained ADA controlled by either the Moloney murine leukemia virus promoter (LASN) or the cytomegalovirus promoter (LNCA) expressed ADA at much higher levels than the other vectors tested. Furthermore, in K562 cells infected with LASN and LNCA vectors, induction of terminal differentiation resulted in the same or higher level expression of ADA. These cell lines have permitted the evaluation of transduced gene expression in proliferating and differentiating hematopoietic cells that provide a model for bone marrow-targeted gene therapy.
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PMID:Expression of human adenosine deaminase from various strong promoters after gene transfer into human hematopoietic cell lines. 275 48

The amount and sequence complexity of RNA transcribed by the murine leukemia virus (MuLV) genome and to the alpha- and beta-globin genes in thymus, brain and liver were measured throughout the life span of AKR mice using a cDNA X RNA hybridization technique. RNA complementary to the complete sequence of specific cDNA probes for both MuLV and globin was found in nuclei and cytoplasm of thymus, brain and liver at all ages studied. No significant age-dependent change in the amount or sequence complexity of globin RNA was detected. The amount of MuLV RNA in both nuclei and cytoplasm of thymus increased about five times from 2 to 5 months of age, but no significant change was observed over this age range in MuLV RNA from liver and brain. By the age of 10 months, most of the mice had developed leukemia and the thymus showed a further increase in the amount of MuLV RNA. Nuclear RNA from liver and brain then showed a significant increase in the amount of MuLV, but no change in the amount of MuLV was found in the cytoplasm. No qualitative age-dependent changes in the MuLV RNA sequence complexity in thymus, liver and brain were detected. These results suggest that in the AKR mouse strain for the three tissues studied, an age-dependent relaxation occurs in the repression of the MuLV genome but not for alpha- and beta-globin genes. The rate of the depression of MuLV genes in the short-lived AKR mouse strain appears similar to that of the long-lived C57BL/6J mouse strain. This age-dependent relaxation of MuLV genes appears to be limited to the nuclei. Thus, the presence of a specific regulatory system for the transport of MuLV RNA through the nuclear membrane which does not deteriorate with age is indicated.
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PMID:Dysdifferentiative nature of aging: age-dependent expression of MuLV and globin genes in thymus, liver and brain in the AKR mouse strain. 299 53

The coding regions of murine interferon-alpha (IFN-alpha) genes were combined with promoter and 3'-noncoding sequences from other eukaryotic genes. Transient expression of these fusion genes was achieved in monkey COS cells and in a mouse cell line (TOP cells) expressing polyoma virus (Py) large T antigen constitutively. The efficiency of the different expression plasmids was determined by measuring the amount of IFN secreted into the medium. Replacement of the 3'-noncoding region of an IFN-alpha gene by that of the rabbit beta-globin gene resulted in a fourfold higher IFN-alpha production. The SV40 early promoter and the Moloney murine leukemia virus (MoMLV) long terminal repeat (LTR) produced similar amounts of IFN-alpha in COS cells. However, a tandem combination of the SV40 enhancer/early promoter and the mouse metallothionein-I promoter appeared fivefold more active than the SV40 early promoter. In TOP cells the MoMLV LTR was found to be threefold more active than the Py early promoter.
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PMID:Transient expression of murine interferon-alpha genes in mouse and monkey cells. 302 4

The human T-cell leukemia virus type I (HTLV-I) p40x protein is a 40-kilodalton polypeptide encoded in the 3'-terminal region of the virus. This protein is responsible for positive transcriptional trans-activation of promoter elements located within the HTLV-I long terminal repeat. We introduced the protein-coding region of HTLV-I p40x into the genome of the baculovirus Autographa californica nuclear polyhedrosis virus. After infection of the insect Spodoptera frugiperda (SF9) cell line, this recombinant strain of baculovirus produced approximately 200 mg of intact p40x protein per 2.5 X 10(8) cells. The protein was biologically active in trans-activation of an HTLV-I long terminal repeat-human beta-globin construct. Biochemical analyses of the protein suggest that the p40x polypeptide underwent posttranslational modification in these eucaryotic SF9 cells.
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PMID:Abundant synthesis of functional human T-cell leukemia virus type I p40x protein in eucaryotic cells by using a baculovirus expression vector. 302 97

We have cloned human beta-globin DNA sequences from a genomic library prepared from DNA isolated from the human leukemia cell line K562 and have used the retroviral vector pZip-NeoSV(X)1 to introduce a 3.0-kilobase segment encompassing the globin gene into mouse erythroleukemia cells. Whereas the endogenous K562 beta-globin gene is repressed in K562 cells, when introduced into mouse erythroleukemia cells by retroviral-mediated gene transfer, the beta-globin gene from K562 cells was transcribed and induced 5-20-fold after treatment of the cells with dimethyl sulfoxide. The transcripts were correctly initiated, and expression and regulation of the K562 gene were identical to the expression of a normal human beta-globin gene transferred into mouse erythroleukemia cells in the same way. We have also introduced the normal human beta-globin gene into K562 cells using the same retrovirus vector. SP6 analysis of the RNA isolated from the transduced cells showed that the normal beta-globin gene was transcribed at a moderately high level, before or after treatment with hemin. Based on these data, we suggest that the lack of expression of the endogenous beta-globin gene in K562 cells does not result from an alteration in the gene itself and may not result from a lack of factor(s) necessary for beta-globin gene transcription. Retroviral-mediated transfer of the human beta-globin gene may, however, uniquely influence expression of the gene in K562 cells.
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PMID:Retroviral-mediated transfer and expression of human beta-globin genes in cultured murine and human erythroid cells. 316 12

The K562 human leukemia cell is an erythroid-like cell that may serve as a model for the study of globin gene expression in transcriptionally active human erythroid cells. K562 cells express all globin genes with the exception of that for beta-globin; failure to produce beta-globin could result from an acquired mutation in each of the beta-globin genes or from an alteration in the regulatory factor environment of the beta-globin gene. To uncover a possible acquired mutation, restriction endonuclease analysis of genomic K562 DNA and expression studies of a cloned K562 beta-globin gene were carried out. Restriction endonuclease analysis revealed no structural alteration of the K562 beta-globin genes. Analysis of the polymorphic Ava II site in intervening sequence 2 of the beta-globin gene showed that K562 cells contain two different beta-globin alleles, both of which are inactive. A K562 beta-globin gene was cloned, ligated into the expression vector pLTN3B, and introduced into COS cells. Transcripts were analyzed by RNA blot, dot blot, S1 nuclease mapping, and primer extension assay. The cloned K562 beta-globin gene was transcribed in COS cells as efficiently as a normal beta-globin gene introduced into COS cells; the mRNA was 10 S and polyadenylylated; the 5' and 3' termini and the processing of transcripts were identical to that of mRNA transcribed from a normal gene. Based on these data we suggest that the absence of beta-globin gene expression results not from an alteration in the beta-globin gene, but from a quantitative or qualitative alteration in a trans-acting factor important in beta-globin gene expression.
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PMID:A beta-globin gene, inactive in the K562 leukemic cell, functions normally in a heterologous expression system. 620 98

K562 human leukemia cells synthesize embryonic hemoglobins after culture in the presence of hemin. We have rigorously identified these hemoglobins by globin chain analysis and peptide mapping. No adult hemoglobin could be detected, and beta-globin synthesis was less than 2 ppm of total protein synthesis. Persistent embryonic globin gene expression is known to occur as a consequence of globin gene deletions. However, restriction endonuclease mapping showed that the globin gene complexes in K562 cells are indistinguishable from normal. Hemin increased the rate of embryonic globin synthesis. The pattern of hemoglobin synthesis proved to be stable when cells from different laboratories were compared. One line, however, synthesized large amounts of Hb X and very little Hb Portland in response to hemin. Hb X has been previously detected in human embryos; we show here that it has the composition epsilon 2 gamma 2 and is diagnostic of imbalanced chain synthesis or "zeta thalassemia." We have identified several agents that induce hemoglobin synthesis in K562 cells. Different inducers induced different patterns of embryonic hemoglobin synthesis but never any adult hemoglobin synthesis.
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PMID:Embryonic erythroid differentiation in the human leukemic cell line K562. 626 39

Non-random tumour-specific chromosomal abnormalities have been observed in cells of many different human tumours. In Wilms' tumour (WT) and retinoblastoma, a chromosomal deletion occurs germinally or somatically and has been considered an important step in tumour development. One class of potential cellular transforming genes comprises the cellular homologues of the transforming genes of highly oncogenic retroviruses. A remarkable concordance between the chromosomal location of human cellular oncogenes and the breakpoints involved in acquired chromosomal translocations is becoming apparent in various cancers: the oncogenes c-mos, c-myc and c-abl are located at the breakpoints that occur in acute myeloblastic leukaemia, Burkitt's lymphoma and chronic myelocytic leukaemia respectively. Thus when the oncogene c-Ha-ras1 was localized to the short arm of human chromosome 11 (refs 6-8; region 11p11 leads to p15 and not 11p13 as stated in ref. 5), it was proposed as a possible aetiological agent in the aniridia-WT association (AWTA) that results from a deletion of 11p13 (although a transforming gene recently isolated from a WT cell line (G401) was shown not to be homologous to either c-Ha-ras or c-Ki-ras9). We have now looked for deletion or rearrangement of c-Ha-ras1 in the DNA from four subjects with del(11p13)-associated predisposition to Wilms' tumour, aniridia, genitourinary abnormalities and mental retardation. We report here that in no case is c-Ha-ras1 deleted, and we have further refined its location to 11p15.1 leads to 11p15.5. On the basis of enzyme studies and direct gene dosage determination for c-Ha-ras1 and beta-globin in neoplastic and non-neoplastic tissues from one patient, we conclude that deletion of the normal counterpart of 11p cannot account for the development of the tumour.
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PMID:c-Ha-ras1 is not deleted in aniridia-Wilms' tumour association. 631 28

Human leukemia K562(S) cells were induced to differentiate by 50 microM hemin or 1.4 mM butyric acid, and the types of hemoglobins synthesized were compared. In both cases, embryonal hemoglobins [Portland, Gower 1, Hb X, and fetal hemoglobin (Hb-F)] were detected. Butyric acid-treated K562(S) cells contained mostly Hb Gower 1 (zeta 2 epsilon 2) and a hemoglobin with the electrophoretic characteristics of Portland (gamma 2 zeta 2). For hemin-treated K562(S), the most abundant hemoglobin synthesized by Hb X (epsilon 2 gamma 2), and the second most abundant was Bart's (gamma 4). Traces of Gower 1 were observed in nontreated K562(S) cells. The kinetics of hemoglobin induction as a result of the two treatments differed; increased hemoglobin synthesis was detected after only 24 hr of hemin treatment, whereas 4 days were required in butyric acid-treated cells. Both hemin and butyric acid were able to induce their respective patterns of hemoglobin synthesis independent of the presence of serum in the K562(S) growth medium. Analysis of the globin chains in induced K562(S) cells induced to differentiate indicated that, with both inducers, adult alpha- but not beta-globin chains were present. Karyotype analysis of K562(S) cells revealed a nearly triploid chromosome complement with a modal number of 68 chromosomes. Three copies of chromosome 11 and four copies of chromosome 16 (coding for the beta-like and alpha-like globin genes, respectively) were present. A large marked chromosome, involving chromosome 7, and a Philadelphia chromosome were also seen. These data characterize the K562(S) subline and also indicate that hemin and butyric acid differ in their effects on the expression of embryonal globin genes.
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PMID:Differential expression of the globin genes in human leukemia K562(S) cells induced to differentiate by hemin or butyric acid. 693 48

The DNase I hypersensitive site 5' HS2 of the human beta-globin locus control region confers position-independent, high-level expression on the human beta-globin gene in transgenic mice. When a 5' HS2 beta-globin construct is flanked by retroviral vector sequences derived from Moloney Murine Leukemia Virus (MoMLV), expression of the beta-globin gene is severely inhibited. Apparently, one or more elements within the MoMLV genome is capable of repressing transcription of the human beta-globin gene in transgenic mice. A construct lacking the retroviral enhancer also fails to express the beta-globin gene, indicating that this region of the virus is not essential for repression. Further analysis may permit the identification of specific viral sequences that inhibit gene expression; these sequences could then be deleted or mutated to produce improved viral vectors.
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PMID:Retroviral vector sequences inhibit human beta-globin gene expression in transgenic mice. 797 Dec 78


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