Activation of EVI1 gene expression in human acute myelogenous leukemias by translocations spanning 300-400 kilobases on chromosome band 3q26.

Abstract

Retroviral activation ofEvi-l gene expression is one of the most common transforming events in murine myeloid leukemias. To evaluate the role of the EVII gene in human acute myelogenous leukemia (AML), leukemic blasts or cell lines from 116 patients were examined. In eight patients the EVII gene was expressed and all but one had cytogenetically detectable translocations of chromosome 3q26 where the EVII gene has been localized. To identify breakpoints, a restriction map that spans 1700 kilobases (kb) of the EVII locus was developed by pulsed-field gel electrophoresis. In one case, t(3;3)(q21;q26), a rearrangement was localized to 170-330 kb 5' of the gene. In a second case, t(3;3)(q21;q26), there was a rearrangement 13 kb 5' of the gene. This rearrangement was cloned and shown to be due to the fusion of sequences from 3q21-22 with the EVII locus. In the third case, ins(3)-(q21q25q27), there was a rearrangement that mapped 150 kb downstream from the 5' end of the gene.Human acute myelogenous leukemia (AML) is associated with a number of recurring chromosomal abnormalities. Only recently have the genes associated with these cytogenetic changes been identified. One region of recurring abnormalities involves chromosome band 3q26 and includes t(3;3)(q21 ;q26), inv(3)(q21q26), t(2;3)(p21 ;q26), t(3;21)(q26;q22), and t(3 ;5)(q25

The EVI1 gene in myeloid leukemia

“…So far, by using pulsed field gel electrophoresis (PFGE) and fluorescence in situ hybridization (FISH) analyses, the breakpoints of the 3;3 translocations have been mapped 5Ј of EVI1, whereas the breakpoints of the inv(3) have been mapped 3Ј of the gene (Figure 2). 37,38 This defined orientation of the two breakpoints on chromosome 3 suggested that the activation could occur through inappropriate juxtaposition of EVI1 to the regulatory sequence of a gene located at 3q21. After cloning and molecular analysis of breakpoint junctions of the t(3;3) and inv(3), it was determined that both these rearrangements juxtapose the enhancer of the constitutively expressed housekeeping gene Ribophorin I to the coding region of EVI1.…”

“…38 The breakpoints of the t(3;3) are not localized to a restricted region upstream of EVI1, but occur over a genomic region of 13-300 kb 5Ј of the gene, and lead to full activation of the gene by juxtaposition of the Ribophorin I enhancer. 37,38 Although inappropriate activation of genes caused by chromosomal rearrangements over such a large distance are not very common, they have been reported before.…”

Evi-1 ZF1 DNA binding activity and a second distinct transcriptional repressor region are both required for optimal transformation of Rat1 fibroblasts

“…Primary murine (Bergeron et al, 1992) and human leukaemia cells (Morishita et al, 1992a) also have retroviral insertions or translocations, respectively, which activate Evi-1 gene expression. Several lines of evidence strongly suggest that the activation of Evi-1 expression contributes to cell transformation: (1) Some translocations produce either a truncated (Ogawa et al, 1996;Suzukawa et al, 1997) or a fusion Evi-1 protein product (Mitani et al, 1994); (2) Evi-1 is overexpressed in ovarian cancers (Brooks et al, 1996) suggesting a link with other cancers as well as leukaemia; (3) Constitutive Evi-1 expression in both primary erythroid progenitor cells and 32Dcl3 myeloid cells (Morishita et al, 1992b) results in the loss of erythropoietin responsiveness and G-CSF-dependent survival respectively; and (4) Evi-1 transforms Rat1 ®broblasts (Kurokawa et al, 1995).…”

Unbalanced t(3;12) in a case of juvenile myelomonocytic leukemia (JMML) results in partial trisomy of 3q as defined by FISH

“…The abnormal expression of the EVI-1 gene has been assonarrowed the breakpoint region to the interval between YACs 929a11 and 807g5, bands 3q21-22 (Figure 1). ciated with blast crisis of CML, AMLs and myelodysplastic syndromes [25][26][27][28] and we showed that EVI-1 is maintained on Finally the karyotype of the leukemic cells from our JMML patient was revised as 46,XX,der(12)t(3;12)(q21 ෂ 22;p13.33).…”