title: Supraphysiologic levels of the AML1-ETO isoform AE9a are essential for transformation.
abstract: Chromosomal translocation 8;21 is found in 40% of the FAB M2 subtype of acute myeloid leukemia (AML). The resultant in-frame fusion protein AML1-ETO (AE) acts as an initiating oncogene for leukemia development. AE immortalizes human CD34(+) cord blood cells in long-term culture. We assessed the transforming properties of the alternatively spliced AE isoform AE9a (or alternative splicing at exon 9), which is fully transforming in a murine retroviral model, in human cord blood cells. Full activity was realized only upon increased fusion protein expression. This effect was recapitulated in the AE9a murine AML model. Cotransduction of AE and AE9a resulted in a strong selective pressure for AE-expressing cells. In the context of AE, AE9a did not show selection for increased expression, affirming observations of human t(8;21) patient samples where full-length AE is the dominant protein detected. Mechanistically, AE9a showed defective transcriptional regulation of AE target genes that was partially corrected at high expression. Together, these results bring an additional perspective to our understanding of AE function and highlight the contribution of oncogene expression level in t(8;21) experimental models.
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229;
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Link
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229;
authors.forename: Shan
authors.initials: S
authors.lastname: Lin
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229;
authors.forename: Mahesh
authors.initials: M
authors.lastname: Shrestha
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229;
authors.forename: Melissa
authors.initials: M
authors.lastname: Bowman
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229;
authors.forename: Mark
authors.initials: M
authors.lastname: Wunderlich
authors.affiliation: The Ohio State University Comprehensive Cancer Center, Columbus, OH 43210;
authors.forename: Clara D
authors.initials: CD
authors.lastname: Bloomfield
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229; Division of Pathology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229.
authors.forename: Gang
authors.initials: G
authors.lastname: Huang
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229; james.mulloy@cchmc.org.
authors.forename: James C
authors.initials: JC
authors.lastname: Mulloy
mesh_terms: D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002891:Chromosomes, Human, Pair 21; D002898:Chromosomes, Human, Pair 8; D050676:Core Binding Factor Alpha 2 Subunit / Q000032:analysis / Q000502:physiology*; D004195:Disease Models, Animal; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000209:etiology* / Q000235:genetics / Q000473:pathology; D051379:Mice; D015514:Oncogene Proteins, Fusion / Q000032:analysis / Q000502:physiology*; D020033:Protein Isoforms; D000075142:RUNX1 Translocation Partner 1 Protein / Q000032:analysis / Q000502:physiology*; D014178:Translocation, Genetic
chemical_list: C107844:AML1-ETO fusion protein, human; D050676:Core Binding Factor Alpha 2 Subunit; D015514:Oncogene Proteins, Fusion; D020033:Protein Isoforms; D000075142:RUNX1 Translocation Partner 1 Protein
keywords: AML; isoform; oncogene dosage; transformation