title: Expression of AML1-ETO in human myelomonocytic cells selectively inhibits granulocytic differentiation and promotes their self-renewal.
abstract: The t(8;21) translocation is one of the most frequent translocations in acute myeloid leukaemia (AML), giving rise to the AML1-ETO fusion protein (or RUNX1-CBF2T1). This abnormality is associated with myelocytic leukaemia with dysplastic granulopoiesis. Here, we demonstrate that when expressed in a normal human (CD34(+)) progenitor population, AML1-ETO selectively inhibits granulocyte colony formation but not monocyte colony formation. In bulk liquid culture, we found that though AML1-ETO transiently inhibited the proliferation of CD34(+) cells, it promoted long-term growth of myeloid cells for more than 80 days, suggesting that differentiation was inhibited. In support of this, cultures expressing AML1-ETO demonstrated enhanced retention of colony-forming capacity. Phenotypic examination of AML1-ETO cultures revealed a defect in granulocytic differentiation in terms of retention of CD34(+) cells within the culture and delayed CD11b upregulation. Morphologically, granulocyte terminal differentiation in AML1-ETO-expressing cells was inhibited by 83+/-5%, giving rise to a build-up of early to intermediate granulocytes that exhibited a number of morphological features associated with t(8;21) leukaemias. In contrast, AML1-ETO had little or no effect on monocytic differentiation. Taken together, these results suggest that expression of AML1-ETO selectively inhibits the differentiation of granulocytic cells and promoted extensive self-renewal, supporting a causal role for t(8;21) translocations in leukaemogenesis.
authors.affiliation: Department of Haematology, University of Wales College of Medicine, Cardiff, UK. tonksa@cf.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Tonks
authors.forename: A J
authors.initials: AJ
authors.lastname: Tonks
authors.forename: L
authors.initials: L
authors.lastname: Pearn
authors.forename: L
authors.initials: L
authors.lastname: Pearce
authors.forename: T
authors.initials: T
authors.lastname: Hoy
authors.forename: S
authors.initials: S
authors.lastname: Couzens
authors.forename: J
authors.initials: J
authors.lastname: Fisher
authors.forename: A K
authors.initials: AK
authors.lastname: Burnett
authors.forename: R L
authors.initials: RL
authors.lastname: Darley
mesh_terms: D018952:Antigens, CD34; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation; D002455:Cell Division; D050676:Core Binding Factor Alpha 2 Subunit; D041905:Erythroid Cells / Q000473:pathology; D042381:Granulocyte Precursor Cells / Q000473:pathology*; D049452:Green Fluorescent Proteins; D006801:Humans; D016130:Immunophenotyping; D015479:Leukemia, Myelomonocytic, Acute / Q000209:etiology / Q000473:pathology*; D008164:Luminescent Proteins / Q000235:genetics; D022423:Myeloid Cells / Q000473:pathology; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000502:physiology*; D000075142:RUNX1 Translocation Partner 1 Protein; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014161:Transduction, Genetic
chemical_list: C107844:AML1-ETO fusion protein, human; D018952:Antigens, CD34; D050676:Core Binding Factor Alpha 2 Subunit; D008164:Luminescent Proteins; D015514:Oncogene Proteins, Fusion; D000075142:RUNX1 Translocation Partner 1 Protein; D014157:Transcription Factors; D049452:Green Fluorescent Proteins