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 (

Identification of HIF2α as an important STAT5 target gene in human hematopoietic stem cells

“…11 In human cord blood CD34 ϩ cells, down-modulation of STAT5 resulted in decreased colony-forming cell (CFC) numbers and long-term culture-initiating cell (LTC-IC) frequencies that coincided with a reduction in long-term expansion, whereas cell differentiation was not affected. 12 The most direct evidence for STAT5 acting as an oncogene arises from murine bone marrow transplantation studies in which constitutively activated STAT5 (S711F) mutants were overexpressed. Lethally irradiated recipients receiving activated STAT5-transduced bone marrow died within 6 weeks after transplantation of a multilineage leukemia.…”

“…18 Targeting STAT5 in primary AML CD34 ϩ cells resulted in impaired long-term expansion and a decline in the formation of leukemic cobblestone-area forming cells (CAFCs). 12 Although it is clear that STAT5 fulfills essential roles in both normal hematopoiesis and in the development or maintenance of leukemia, little is known about the molecular mechanisms that are involved. By making use of an inducible model in which constitutive STAT5 activity can be introduced in specific compartments of the hematopoietic system, 24,25 our current data show that STAT5 can impose a long-term proliferative advantage on the CD34 ϩ /CD38 Ϫ HSC population, but not on progenitors.…”

Auto-SCT induces a phenotypic shift from CMP to GMP progenitors, reduces clonogenic potential and enhances in vitro and in vivo cycling activity defined by 18F-FLT PET scanning

“…12 To define the in vitro cycling activity of the CFCs, CD34 þ cells were incubated with variable concentrations of cytarabine (Faulding Pharmaceuticals, Brussels, Belgium), that is, 5 Â 10 À7 M, 1Â 10 À6 M, 5Â 10 À6 M, 7.5Â 10 À6 M, 1 Â 10 À5 M, 5Â 10 À5 M and 1 Â 10 À4 M for 24 h and subsequently plated in the CFC assay. After 14 days the CFC colony number was counted with an inverted microscope.…”

Variability in responsiveness to lovastatin of the primitive CD34+ AML subfraction compared to normal CD34+ cells

“…Patients were classified according to the WHO classification [12]. Mononuclear cells were enriched by FicollIsopaque (Nycomed, Oslo, Norway) density gradient centrifugation and cryopreserved in RPMI 1640 medium (BioWhittaker, Brussels, Belgium) supplemented with 20% fetal calf serum (FCS; Hyclone, Logan, UT, USA) and 20% dimethyl sulfoxide (Merck, Amsterdam, The Netherlands) and stored at −196°C as described [13].…”

“…No difference existed in baseline average and median ATP levels between CD34 + and CD34 − cells. RNA extraction, cDNA synthesis, and quantitative polymerase chain reaction were performed as described before [13].…”