title: STAT5 is required for long-term maintenance of normal and leukemic human stem/progenitor cells.
abstract: The transcription factor STAT5 fulfills a distinct role in the hematopoietic system, but its precise role in primitive human hematopoietic cells remains to be elucidated. Therefore, we performed STAT5 RNAi in sorted cord blood (CB) and acute myeloid leukemia (AML) CD34+ cells by lentiviral transduction and investigated effects of STAT5 downmodulation on the normal stem/progenitor cell compartment and the leukemic counterpart. STAT5 RNAi cells displayed growth impairment, without affecting their differentiation in CB and AML cultures on MS5 stroma. In CB, limiting-dilution assays demonstrated a 3.9-fold reduction in progenitor numbers. Stem cells were enumerated in long-term culture-initiating cell (LTC-IC) assays, and the average LTC-IC frequency was 3.25-fold reduced from 0.13% to 0.04% by STAT5 down-regulation. Single-cell sorting experiments of CB CD34+/CD38(-) cells demonstrated a 2-fold reduced cytokine-driven expansion, with a subsequent 2.3-fold reduction of progenitors. In sorted CD34+ AML cells with constitutive STAT5 phosphorylation (5/8), STAT5 RNAi demonstrated a reduction in cell number (72% +/- 17%) and a decreased expansion (17 +/- 15 vs 80 +/- 58 in control cultures) at week 6 on MS5 stroma. Together, our data indicate that STAT5 expression is required for the maintenance and expansion of primitive hematopoietic stem and progenitor cells, both in normal as well as leukemic hematopoiesis.
authors.affiliation: Division of Hematology, Department of Medicine, University Medical Center Groningen, Groningen, the Netherlands.
authors.forename: Hein
authors.initials: H
authors.lastname: Schepers
authors.forename: Djoke
authors.initials: D
authors.lastname: van Gosliga
authors.forename: Albertus T J
authors.initials: AT
authors.lastname: Wierenga
authors.forename: Bart J L
authors.initials: BJ
authors.lastname: Eggen
authors.forename: Jan Jacob
authors.initials: JJ
authors.lastname: Schuringa
authors.forename: Edo
authors.initials: E
authors.lastname: Vellenga
mesh_terms: D000208:Acute Disease; D018952:Antigens, CD34 / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D005312:Fetal Blood; D005434:Flow Cytometry; D015870:Gene Expression; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D006801:Humans; D007951:Leukemia, Myeloid / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018952:Antigens, CD34; D050799:STAT5 Transcription Factor