Abstract
BackgroundAcute myeloid leukemia (AML) 1-Evi-1 is a chimeric gene generated by the t (3; 21) (q26; q22) translocation, which leads into malignant transformation of hematopoietic stem cells by unclear mechanisms. This in vivo study aimed to establish a stable line of zebrafish expressing the human RUNX1-Evi-1 fusion gene under the control of a heat stress-inducible bidirectional promoter, and investigate its roles in hematopoiesis and hematologic malignancies.MethodsWe introduced human RUNX1-Evi-1 fusion gene into embryonic zebrafish through a heat-shock promoter to establish Tg(RE:HSE:EGFP) zebrafish. Two males and one female mosaic F0 zebrafish embryos (2.1 %) were identified as stable positive germline transgenic zebrafish.ResultsThe population of immature myeloid cells and hematopoietic blast cells were accumulated in peripheral blood and single cell suspension from kidney of adult Tg(RE:HSE:EGFP) zebrafish. RUNX1-Evi-1 presented an intensive influence on hematopoietic regulatory factors. Consequently, primitive hematopoiesis was enhanced by upregulation of gata2 and scl, while erythropoiesis was downregulated due to the suppression of gata1. Early stage of myelopoiesis was flourishing with the high expression of pu.1, but it was inhibited along with the low expression of mpo. Microarray analysis demonstrated that RUNX1-Evi-1 not only upregulated proteasome, cell cycle, glycolysis/gluconeogenesis, tyrosine metabolism, drug metabolism, and PPAR pathway, but also suppressed transforming growth factor β, Jak-STAT, DNA replication, mismatch repair, p53 pathway, JNK signaling pathway, and nucleotide excision repair. Interestingly, histone deacetylase 4 was significantly up-regulated. Factors in cell proliferation were obviously suppressed after 3-day treatment with histone deacetylase inhibitor, valproic acid. Accordingly, higher proportion of G1 arrest and apoptosis were manifested by the propidium iodide staining.ConclusionRUNX1-Evi-1 may promote proliferation and apoptosis resistance of primitive hematopoietic cell, and inhibit the differentiation of myeloid cells with the synergy of different pathways and factors. VPA may be a promising choice in the molecular targeting therapy of RUNX1-Evi-1-related leukemia.
Highlights
Acute myeloid leukemia (AML) 1-Ecotropic viral integration site (Evi)-1 is a chimeric gene generated by the t (3; 21) (q26; q22) translocation, which leads into malignant transformation of hematopoietic stem cells by unclear mechanisms
Bone marrow cells of murine transduced with Evi-1 alone cannot cause leukemia [3], while deletion of RUNX1 alone does not immortalize bone marrow cells [4], which suggest that both suppression of RUNX1 and activation of Evi-1 are required for RUNX1-Evi-1 leukemogenesis
Establishment of Tg(RE:HSE:EGFP) zebrafish line About 40 % of the embryos injected with the pSGH2RUNX1-Evi-1 plasmid exhibited EGFP+ expression after heat shock at 38°Cfor an hour
Summary
Acute myeloid leukemia (AML) 1-Evi-1 is a chimeric gene generated by the t (3; 21) (q26; q22) translocation, which leads into malignant transformation of hematopoietic stem cells by unclear mechanisms. The disease could be readily transferred into secondary recipients with a much shorter latency [6] In another distinct BMT mouse model, Evi-1 seemed to collaborate with an RUNX1 mutant harboring a point mutation in the Runt homology domain (D171N) to induce with an identical phenotype characterized by marked hepatosplenomegaly, myeloid dysplasia, leukocytosis, and biphenotypic surface markers [7]. All of these sick mice died soon after transplantation, and generation of transgenic offspring to carry on the follow-up study is impossible
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