title: The AML1-ETO fusion protein promotes the expansion of human hematopoietic stem cells.
abstract: The acute myelogenous leukemia-1 (AML1)-ETO fusion protein is generated by the t(8;21), which is found in 40% of AMLs of the French-American-British M2 subtype. AML1-ETO interferes with the function of the AML1 (RUNX1, CBFA2) transcription factor in a dominant-negative fashion and represses transcription by binding its consensus DNA-binding site and via protein-protein interactions with other transcription factors. AML1 activity is critical for the development of definitive hematopoiesis, and haploinsufficiency of AML1 has been linked to a propensity to develop AML. Murine experiments suggest that AML1-ETO expression may not be sufficient for leukemogenesis; however, like the BCR-ABL isoforms, the cellular background in which these fusion proteins are expressed may be critical to the phenotype observed. Retroviral gene transfer was used to examine the effect of AML1-ETO on the in vitro behavior of human hematopoietic stem and progenitor cells. Following transduction of CD34(+) cells, stem and progenitor cells were quantified in clonogenic assays, cytokine-driven expansion cultures, and long-term stromal cocultures. Expression of AML1-ETO inhibited colony formation by committed progenitors, but enhanced the growth of stem cells (cobblestone area-forming cells), resulting in a profound survival advantage of transduced over nontransduced cells. AML1-ETO-expressing cells retained progenitor activity and continued to express CD34 throughout the 5-week long-term culture. Thus, AML1-ETO enhances the self-renewal of pluripotent stem cells, the physiological target of many acute myeloid leukemias.
authors.affiliation: Laboratory of Molecular Hematopoiesis, Sloan-Kettering Institute, New York, NY, USA. j-mulloy@ski.mskcc.org
authors.forename: James C
authors.initials: JC
authors.lastname: Mulloy
authors.forename: Jörg
authors.initials: J
authors.lastname: Cammenga
authors.forename: Karen L
authors.initials: KL
authors.lastname: MacKenzie
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Berguido
authors.forename: Malcolm A S
authors.initials: MA
authors.lastname: Moore
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Nimer
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D002455:Cell Division; D002460:Cell Line; D002470:Cell Survival; D018920:Coculture Techniques; D003114:Colony-Forming Units Assay; D050676:Core Binding Factor Alpha 2 Subunit; D016207:Cytokines / Q000494:pharmacology; D005434:Flow Cytometry; D015870:Gene Expression; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000502:physiology*; D000075142:RUNX1 Translocation Partner 1 Protein; D012190:Retroviridae / Q000235:genetics; D017154:Stromal Cells / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014162:Transfection
chemical_list: C107844:AML1-ETO fusion protein, human; D018952:Antigens, CD34; D050676:Core Binding Factor Alpha 2 Subunit; D016207:Cytokines; D008164:Luminescent Proteins; D015514:Oncogene Proteins, Fusion; D000075142:RUNX1 Translocation Partner 1 Protein; D014157:Transcription Factors; D049452:Green Fluorescent Proteins