title: N-Ras(G12D) induces features of stepwise transformation in preleukemic human umbilical cord blood cultures expressing the AML1-ETO fusion gene.
abstract: AML1-ETO (AE) is a fusion product of t(8;21) observed in 40% French-American-British M2 type of acute myeloid leukemia (AML). Clinical data suggest that Ras mutation is a frequent cooperating event in t(8;21) AML. Whether constitutively active Ras promotes leukemogenesis on the t(8;21) background has not been demonstrated experimentally. Here, we retrovirally expressed N-Ras(G12D) in AE-expressing human hematopoietic cells to investigate cooperativity. The AE/N-Ras(G12D) cultures were cytokine-independent, enriched for CD34 positivity, and possessed increased colony-forming and replating abilities. N-Ras(G12D) expression led to Bcl-2 up-regulation and reduced apoptosis. Ectopic Bcl-2 expression also resulted in enhanced colony-forming and replating abilities but was insufficient to sustain cytokine independence. AE/N-Ras(G12D) cells were more sensitive to Bcl-2 inhibition with ABT-737 than parent AE cells. Enhanced engraftment of AE/N-Ras(G12D) cells was observed on intrafemoral injection into immunodeficient mice, presumably because of improved survival in the bone marrow microenvironment. N-Ras(G12D) promotes progression toward transformation in AE-expressing cells, partially through up-regulating Bcl-2.
authors.affiliation: Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Fu-Sheng
authors.initials: FS
authors.lastname: Chou
authors.forename: Mark
authors.initials: M
authors.lastname: Wunderlich
authors.forename: Andrea
authors.initials: A
authors.lastname: Griesinger
authors.forename: James C
authors.initials: JC
authors.lastname: Mulloy
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D003043:Cocarcinogenesis; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics*; D005312:Fetal Blood / Q000166:cytology* / Q000378:metabolism*; D011905:Genes, ras; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000209:etiology / Q000235:genetics* / Q000473:pathology*; D051379:Mice; D008957:Models, Genetic; D009154:Mutation; D009368:Neoplasm Transplantation; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D011289:Preleukemia / Q000209:etiology / Q000235:genetics / Q000473:pathology; D000075142:RUNX1 Translocation Partner 1 Protein; D014161:Transduction, Genetic; D014183:Transplantation, Heterologous
chemical_list: C107844:AML1-ETO fusion protein, human; D050676:Core Binding Factor Alpha 2 Subunit; D015514:Oncogene Proteins, Fusion; D000075142:RUNX1 Translocation Partner 1 Protein