| 1. |
- Ageberg, Malin, et al.
(författare)
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Identification of a novel and myeloid specific role of the leukemia-associated fusion protein DEK-NUP214 leading to increased protein synthesis.
- 2008
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Ingår i: Genes, Chromosomes and Cancer. - : Wiley. - 1045-2257 .- 1098-2264. ; 47, s. 276-287
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Tidskriftsartikel (refereegranskat)abstract
- The t(6;9)(p22;q34) chromosomal translocation is found in a subset of patients with acute myeloid leukemia (AML). The translocation results in a fusion between the nuclear phosphoprotein DEK and the nucleoporin NUP214 (previously CAN). The mechanism by which the fusion protein DEK-NUP214 contributes to leukemia development has not been identified, and disruptions of normal cellular functions by DEK-NUP214 have previously not been described. In the present study, a novel effect of the DEK-NUP214 fusion protein is demonstrated. Our findings reveal a substantial increase in global protein synthesis in DEK-NUP214 expressing cells. Furthermore, we conclude that this effect is not the result of dysregulated transcription but merely due to increased translation. Consistent with the association with AML, the increased protein synthesis mediated by DEK-NUP214 is restricted to cells of the myeloid lineage. Analysis of potential mechanisms for regulating protein synthesis shows that expression of DEK-NUP214 correlates to the phosphorylation of the translation initiation protein, EIF4E. The present data provide evidence that increase of translational activity constitutes a mechanism by which the leukemogenic effect of DEK-NUP124 may be mediated. (c) 2008 Wiley-Liss, Inc.
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| 2. |
- Bergh, Gösta, et al.
(författare)
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Altered expression of the retinoblastoma tumor-suppressor gene in leukemic cell lines inhibits induction of differentiation but not G1-accumulation
- 1997
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Ingår i: Blood. - 1528-0020. ; 89:8, s. 2938-2950
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Tidskriftsartikel (refereegranskat)abstract
- The retinoblastoma tumor-suppressor gene, RB, has been implicated in tumor suppression, in regulation of the cell cycle, and in mediating cell differentiation. RB is necessary for hematopoiesis in mice, and aberrant RB-expression is associated with the progress and prognosis of leukemia. We have used antisense oligonucleotides, established clones stably expressing an antisense RB construct, and also established clones over expressing the retinoblastoma protein (pRb) to study the role of RB expression in monocytic differentiation induced by all-trans retinoic acid (ATRA) or 1-alpha-25-dihyroxycholecalciferol (Vit D3) in the monoblastic cell line U-937 and erythroid differentiation induced by transforming growth factor beta1 (TGFbeta1) and hemin in the erythroleukemic cell line K562. A reduction in pRb production in antisense RB-transfected U-937 clones was shown. Antisense oligonucleotides as well as expression of the antisense RB construct suppressed differentiation responses to ATRA or Vit D3, as judged by the capability to reduce nitro blue tetrazolium, by the appearance of monocyte-related cell surface antigens and by morphologic criteria. K562 cells showed decreased differentiation response to TGFbeta1, but not to hemin, when incubated with antisense oligonucleotides. U-937 antisense RB-transfected cells were also suppressed in their ability to upregulate levels of hypophosphorylated pRb when induced to differentiate. Although U-937 cells incubated with antisense oligonucleotides and clones expressing the antisense RB construct were hampered in their ability to differentiate on incubation with ATRA or Vit D3, the induced G0/G1-accumulation was similar to differentiating control cells treated with ATRA or Vit D3. Intriguingly, U-937 clones overexpressing RB were also inhibited in their differentiation response to ATRA or Vit D3 but not inhibited in their ability to respond with G0/G1 accumulation when induced with these substances. The results indicate that pRb plays a role in induced differentiation of U-937 cells as well as K562 cells involving mechanisms that, at least partially, are distinct from those inducing G1 accumulation.
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| 3. |
- Ehinger, Mats, et al.
(författare)
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Expression of the p53 tumor suppressor gene induces differentiation and promotes induction of differentiation by 1,25-dihydroxycholecalciferol in leukemic U-937 cells
- 1996
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Ingår i: Blood. - 1528-0020. ; 87:3, s. 1064-1074
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Tidskriftsartikel (refereegranskat)abstract
- Leukemic U-937 cells, which lack normal p53, were stably transfected with a temperature-sensitive mutant of p53 to investigate the consequences for growth and differentiation. On induction of wild-type p53 activity at the permissive temperature, some of these cells underwent maturation as judged by the capacity for oxidative burst and the appearance of monocyte related cell surface molecules. Moreover, wild-type p53-expressing cells were more sensitive than p53-negative control cells to induction of differentiation by 1,25-dihydroxycholecalciferol; a twofold to fourfold increase of the fraction of cells showing signs of terminal maturation was observed when wild-type p53-expressing cells were incubated with 1,25-dihydroxycholecalciferol at concentrations that only slightly affected control cells. Whereas wild-type p53 activity per se induced maturation of certain cells, other underwent cell death judging from the reduced capability to exclude trypan blue and the appearance of fragmented DNA in flow cytometric analysis. The p53-induced cell death could be inhibited by incubation with 1,25-dihydroxy-cholecalciferol, but not all-trans retinoic acid. Thus, 1,25-dihydroxycholecalciferol, seemed to increase the survival of wild-type p53-expressing cells and to cooperate with wild-type p53 to induce differentiation. The data imply that p53-mediated maturation in U-937 cells depends on optimal regulation of signals for differentiation, survival and proliferation, and suggest a role for p53 in the differentiation induction of leukemic cells.
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| 4. |
- Hakansson, P., et al.
(författare)
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Establishment and phenotypic characterization of human U937 cells with inducible P210 BCR/ABL expression reveals upregulation of CEACAM1 (CD66a)
- 2004
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 0887-6924 .- 1476-5551. ; 18:3, s. 538-47
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Tidskriftsartikel (refereegranskat)abstract
- Chronic myeloid leukemia (CML) is characterized by the expression of the P210 BCR/ABL fusion protein. The molecular mechanisms behind this oncogene-mediated hematological disease are, however, not fully understood. Here, we describe the establishment and phenotypic characterization of U937 cells in which P210 BCR/ABL can be conditionally expressed using tetracycline. The induction of BCR/ABL in the obtained clones resulted in a rapid phosphorylation of the STAT1, STAT3 and STAT5 molecules, consistent with the findings in other model systems. Phenotypic characterization of the clones revealed that BCR/ABL induces a slight decrease in the proliferation and viability, without a marked effect on cell cycle distribution, the rate of apoptosis or on cellular differentiation, as judged by several cell surface markers and capacity to reduce nitro blue tetrazolium. Interestingly, BCR/ABL was found to upregulate the expression of carcinoembryonic-related antigen (CEA)CAM1 (CD66a), which is a plasma membrane-linked glycoprotein belonging to the CEAs and involved in signal transduction and cellular adhesion. The expression of CEACAM1 was reversible upon imatinib treatment in BCR/ABL-expressing U937 cells as well as in BCR/ABL-positive K562 cells. The established cell lines may prove useful in further modeling and dissection of BCR/ABL-induced leukemogenesis.
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| 5. |
- Obad, Susanna, et al.
(författare)
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Expression of the IFN-inducible p53-target gene TRIM22 is down-regulated during erythroid differentiation of human bone marrow.
- 2007
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Ingår i: Leukemia Research: A Forum for Studies on Leukemia and Normal Hemopoiesis. - : Elsevier BV. - 1873-5835. ; 31:7, s. 995-1001
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Tidskriftsartikel (refereegranskat)abstract
- The interferon inducible protein TRIM22 has been identified as a p53 target gene, with possible involvement in proliferation and differentiation of leukaemia cells. Here, the expression levels of TRIM22 during haematopoietic differentiation are characterised. Expression of TRIM22 correlates inversely to differentiation, as TRIM22 is highly expressed in CD34(+) human bone marrow progenitor cells, but declines in mature populations. The erythroid lineage appears as a special case, as TRIM22 expression shows an extreme decrease during late erythroid maturation and is completely undetectable in nucleated erythroid populations in contrast to other lineages. In conclusion, our data Could suggest lineage-specific roles for TRIM22 during haematopoietic differentiation.
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| 6. |
- Obad, Susanna, et al.
(författare)
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Regulation of the interferon-inducible p53 target gene TRIM22 (Staf50) in human T lymphocyte activation
- 2007
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Ingår i: Journal of Interferon and Cytokine Research. - : Mary Ann Liebert Inc. - 1079-9907 .- 1557-7465. ; 27:10, s. 857-864
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Tidskriftsartikel (refereegranskat)abstract
- TRIM22 (Staf50) is an interferon (IFN)-inducible protein with unknown function. Recently, we identified TRIM22 as a novel p53 target gene and showed that overexpression of TRIM22 inhibits the clonogenic growth of monoblastic U937 cells. Moreover, expression of TRIM22 is high in lymphoid tissue, and levels decrease during T lymphocyte activation with CD3/CD2/CD28, suggesting that TRIM22 could exert antiproliferative effects. Here, a prominent increase in TRIM22 levels is observed during activation with interleukin-2 (IL-2) or IL-15 in contrast to the decrease observed during CD3/CD2/CD28-induced activation. However, stimulation of cells in these experiments was performed on crude T lymphocytes, allowing indirect regulation between different lymphocyte subtypes to take place. Therefore, to prevent interaction between different lymphocyte subtypes, expression of TRIM22 was examined during activation of sorted T lymphocyte subpopulations. In contrast to the marked changes of TRIM22 during activation of crude T lymphocytes, in isolated subpopulations, TRIM22 expression was not significantly affected in spite of IL-2-induced or CD3/CD2/CD28-induced activation. In addition, in contrast to the TRIM22 mouse ortholog Rpt-1, TRIM22 did not affect levels of CD25 (IL-2R alpha) mRNA. Our data suggest a more complex role for TRIM22 during T lymphocyte activation than merely as an antiproliferative factor. TRIM22 probably has an activation stage-specific role connected to the paracrine crosstalk during T lymphocyte activation.
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| 7. |
- Sköld, Stefan, et al.
(författare)
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Functional dissociation between proforms and mature forms of proteinase 3, azurocidin, and granzyme B in regulation of granulopoiesis.
- 2002
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Ingår i: Experimental Hematology. - 1873-2399. ; 30:7, s. 689-696
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Tidskriftsartikel (refereegranskat)abstract
- We previously demonstrated that secreted proform(s) of the neutrophil serine protease PR3 (proteinase 3) can down-modulate the fraction of normal human colony-forming unit granulocyte-macrophage (CFU-GM) in S-phase, whereas PR3 extracted from mature neutrophils lacks this ability. The objective of this study was to characterize the structural and functional dissociation between secreted proforms and granule-stored mature forms and to extend the investigation to other related hematopoietic serine proteases.Conditioned media containing secreted proteases from transfectant cell lines with stable expression of human PR3, neutrophil elastase, cathepsin G, azurocidin, and granzymes A, B, H, K, and M were tested for their ability to reduce the fraction of normal human CFU-GM in S phase. Furthermore, recombinant PR3, azurocidin, and granzyme B with defined N-terminal propeptides, and the respective mature forms without propeptide, were functionally characterized.In addition to PR3, secreted proforms of azurocidin and granzymes A, B, H, K, and M, but not cathepsin G or neutrophil elastase, have S-phase reducing activity. This activity is restricted to the dipeptide proforms, whereas mature forms without propeptide have no S-phase reducing activity. On the other hand, only the mature forms of PR3 and granzyme B could bind the serine protease inhibitor diisopropylfluorophosphate (DFP), or aprotinin in the case of azurocidin. We also demonstrate that granulocyte colony-stimulating factor-stimulated CD34(+) cells and interleukin-2-stimulated lymphocytes secrete active proforms of PR3 and granzyme B, respectively.These results demonstrate distinctive functional and conformational differences between proforms and mature forms of these hematopoietic serine proteases and suggest novel growth regulatory mechanisms in granulopoiesis.
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| 8. |
- Svensson, Emelie, et al.
(författare)
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Deregulation of the Wilms' tumour gene 1 protein (WT1) by BCR/ABL1 mediates resistance to imatinib in human leukaemia cells
- 2007
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Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 21:12, s. 2485-2494
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Tidskriftsartikel (refereegranskat)abstract
- The Wilms' tumour gene 1 (WT1) protein is highly expressed in most leukaemias. Co-expression of WT1 and the fusion protein AML1-ETO in mice rapidly induces acute myeloid leukaemia (AML). Mechanisms behind expression of WT1, as well as consequences thereof, are still unclear. Here, we report that the fusion protein BCR/ABL1 increases expression of WT1 mRNA and protein via the phosphatidylinositol-3 kinase (PI3K)-Akt pathway. Inhibition of BCR/ABL1 or PI3K activity strongly suppressed transcription from WT1 promoter/enhancer reporters. Forced expression of BCR/ABL1 in normal human progenitor CD34+ cells increased WT1 mRNA and protein, further supporting the notion of BCR/ABL1-driven expression of WT1 in human haematopoietic cells. Forced expression of WT1 in K562 cells provided protection against cytotoxic effects of the ABL1 tyrosine kinase inhibitor imatinib, as judged by effects on viability measured by trypan blue exclusion, metabolic activity, annexin V and DAPI (4', 6-diamidino-2-phenylindole) staining. None of the isoforms provided any detectable protection against apoptosis induced by arsenic trioxide and only very weak protection against etoposide, indicating that WT1 interferes with specific apoptotic signalling pathways. Our data demonstrate that WT1 expression is induced by oncogenic signalling from BCR/ABL1 and that WT1 contributes to resistance against apoptosis induced by imatinib.
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| 9. |
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| 10. |
- Svensson, Emelie, et al.
(författare)
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The Wilms' tumor gene 1 (WT1) induces expression of the N-myc downstream regulated gene 2 (NDRG2)
- 2007
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Ingår i: DNA and Cell Biology. - : Mary Ann Liebert Inc. - 1044-5498 .- 1557-7430. ; 26:8, s. 589-597
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Tidskriftsartikel (refereegranskat)abstract
- The Wilms' tumor gene 1 (WT1) protein is a transcriptional regulator that is highly expressed in immature hematopoietic progenitor cells and in the majority of patients with acute and chronic myeloid leukemia. However, it is still unclear how WT1 exerts its function(s) in hematopoietic cells. The aim of this work was to investigate the function of WT1 as a transcription factor in human hematopoietic progenitor cells. To this end, an oligonucleotide array approach was used to study the gene expression in CD34(+) cells from human cord blood retrovirally transduced with WT1 or a control vector. We found that the expression of the putative tumor suppressor gene N-myc downstream regulated gene 2 (NDRG2) mRNA was induced by WT1 in CD34(+) cells and also in leukemic U937 cells. Furthermore, a novel transcription start site in the NDRG2 gene was identified in WT1-transduced cells, in addition to two previously reported transcription start sites. These results show that the expression of the NDRG2 gene is directly or indirectly induced by WT1, and provide the first insights into transcriptional regulation of the NDRG2 gene, including demonstration of a novel splice variant.
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