Retroviral insertional activation of the EVI1 oncogene does not prevent G-CSF-induced maturation of the murine pluripotent myeloid cell line 32Dcl3.
ABSTRACT Evi1 is a myeloid-specific protooncogene that encodes 145 kDa and 88 kDa proteins via alternative splicing. Overexpression of the gene via retroviral insertion in murine tumors or chromosomal rearrangement in human tumors is associated with myeloid leukemias and myelodysplasias; however, the mechanism by which such overexpression leads to transformation is not clear. It has been postulated that overexpression of evi1 acts to block normal myelopoiesis. In attempts to assess the effect of overexpression of evi1 on myelopoiesis, we chose to utilize the IL-3-dependent murine 32Dcl3 cell line, which has been shown to differentiate in culture in response to G-CSF. Previous experiments with this cell line, which we have confirmed, showed that overexpression of evi1, mediated by retroviral vector transfer, caused a block to G-CSF-induced cell survival and differentiation. We report here that the naive 32Dcl3 cell line contains a rearrangement of the evi1 locus and constitutively overexpresses evi1 mRNA and protein; this expression is downregulated only slightly during G-CSF-induced myeloid maturation. The steady state levels, molecular weight and DNA binding characteristics of the EVI1 protein in these cells is comparable to that seen in NFS 58, a myeloid leukemia cell line with retroviral insertion at evi1. The observed ability of the murine 32Dcl3 cells to fully differentiate in the presence of G-CSF while evi1 continues to be expressed indicates that, at the levels expressed in naive 32Dcl3, evi1 does not block G-CSF-induced survival and differentiation. Thus, retroviral insertions at evi1 may have been selected for in 32Dcl3 cells due to effects other than that on G-CSF-induced cell survival.
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ABSTRACT: EVI-1 and its variant form, MDS1/EVI1, have been reported to act in an antagonistic manner and be differentially regulated in samples from patients with acute myeloid leukaemia and rearrangements of the long arm of chromosome 3. Here, we show that both EVI-1 and MDS1/EVI1 can repress transcription from a reporter construct containing EVI-1 binding sites and interact with histone deacetylase in mammalian cells. This interaction can be recapitulated in vitro and is mediated by a previously characterized transcription repression domain, whose activity is alleviated by the histone deacetylase inhibitor trichostatin A.British Journal of Haematology 08/2001; 114(3):566 - 573. DOI:10.1046/j.1365-2141.2001.02987.x · 4.96 Impact Factor
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ABSTRACT: Chromosome aberrations affecting band 3q21 are associated with a particularly poor prognosis in patients with acute myeloid leukaemia. To facilitate the molecular characterization of such rearrangements, we established a PAC contig covering the relevant genomic region. Using these PACs as probes in fluorescence in situ hybridization (FISH) experiments, we showed that a number of 3q21 breakpoints in patient samples map to a previously defined ‘breakpoint cluster region’. Others, however, are located at varying distances centromeric of it. These results have important implications in the search for genes affected by 3q21 rearrangements.British Journal of Haematology 07/2000; 110(2):343 - 350. DOI:10.1046/j.1365-2141.2000.02192.x · 4.96 Impact Factor
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ABSTRACT: Activation of the Evi-1 gene was first described to be associated with the transformation of murine myeloid leukaemias and has previously been detected in cases of human acute myeloid leukaemia (AML) and chronic myeloid leukaemia (CML) in blast crises and in myelodysplastic syndromes. In this study we determined the frequency and the level of Evi-1 expression in juvenile myelomonocytic leukaemia (JMML) and in normal haemopoiesis. Using RT-PCR and Southern blot hybridization mRNA of Evi-1 could be detected in bone marrow (BM) and peripheral blood (PB) mononuclear cells (MNC) of normal donors. In JMML 12/20 patients examined expressed elevated levels of Evi-1 compared to normal controls. In these samples over-expression of the gene was correlated with a higher percentage of blasts (P = 0.02). Expression levels in BFU-E and CFU-GM derived colonies from BM of JMML patients were lower than those in the corresponding MNC samples. Analysis of CD34+ and CD34− cells demonstrated that Evi-1 is primarily expressed in the CD34+ cell population of both JMML and normal donors. These findings suggest that Evi-1 expression is linked to the early stages of haemopoiesis. Studies on the regulation of Evi-1 expression in CD34+ cells will elucidate its function in progenitor cells and clarify its possible role in the pathogenesis of JMML.British Journal of Haematology 11/1997; 99(4):882 - 887. DOI:10.1046/j.1365-2141.1997.4983304.x · 4.96 Impact Factor