title: Dominant-negative IKAROS enhances IL-3-stimulated signaling in wild-type but not BCR-ABL1(+) mouse BA/F3 cells.
abstract: Inactivating mutations in IKZF1, the gene that encodes the transcription factor IKAROS, are recurrent in poor-prognosis human B-cell leukemias, in which these mutations co-exist with BCR-ABL1 or other genetic changes that activate similar intracellular signaling pathways. However, little is known about the mechanism(s) by which loss of IKAROS activity may co-operate with BCR-ABL1 to transform lymphoid cells. To investigate this question, we used expression of a dominant-negative isoform of IKAROS (IK6) to suppress endogenous IKAROS activity in the interleukin-3 (IL-3)-dependent mouse pro-B BA/F3 cell line and in an IL-3-independent BCR-ABL1(+) derivative. We then used intracellular phospho-flow cytometry to assess the effects of BCR-ABL1 and IK6, alone and in combination, on the signaling state of the cells before and after their stimulation with IL-3. BCR-ABL1 and IK6 each produced a constitutively activated signaling phenotype and also enhanced the signaling responses of BA/F3 cells to IL-3. These effects, however, were neither equivalent nor additive, and IK6 alone was insufficient to confer the IL-3-independent growth characteristic of BCR-ABL1(+) BA/F3 cells. In addition to its effects on lymphoid cells, IK6 also induced constitutively activated signaling in a subset of myeloid leukemia cell lines. Together, these studies indicate an ability of IK6 to enhance intracellular signaling in both lymphoid and myeloid cells, but not to synergize with BCR-ABL1 in this model system.
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Sofia
authors.initials: S
authors.lastname: von Palffy
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Bulaeva
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Sonja
authors.initials: S
authors.lastname: Babovic
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Nagarajan
authors.initials: N
authors.lastname: Kannan
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: David J H F
authors.initials: DJ
authors.lastname: Knapp
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Wei
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Connie J
authors.initials: CJ
authors.lastname: Eaves
authors.affiliation: Terry Fox Laboratory, British Columbia Cancer Agency and University of British Columbia, Vancouver, British Columbia, Canada. Electronic address: pbeer@doctors.org.uk.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Beer
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D002455:Cell Division; D002461:Cell Line, Transformed; D019070:Cell Lineage; D002470:Cell Survival / Q000187:drug effects; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000502:physiology; D005799:Genes, Dominant; D006801:Humans; D051740:Ikaros Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D007377:Interleukin-3 / Q000819:agonists*; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D009154:Mutation; D022423:Myeloid Cells / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics*; D014161:Transduction, Genetic
chemical_list: C581634:BCR-ABL1 fusion protein, human; C586512:Ikaros 6 protein, human; D007377:Interleukin-3; D011993:Recombinant Fusion Proteins; C497238:Zfpn1a1 protein, mouse; D051740:Ikaros Transcription Factor; D016044:Fusion Proteins, bcr-abl