Schepers Hein, van Gosliga Djoke, Wierenga Albertus T J, Eggen Bart J L, Schuringa Jan Jacob, Vellenga Edo
Division of Hematology, Department of Medicine, University Medical Center Groningen, Groningen, the Netherlands.
Blood. 2007 Oct 15;110(8):2880-8. doi: 10.1182/blood-2006-08-039073. Epub 2007 Jul 13.
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.
转录因子STAT5在造血系统中发挥着独特作用，但其在人类原始造血细胞中的精确作用仍有待阐明。因此，我们通过慢病毒转导在分选的脐带血（CB）和急性髓系白血病（AML）CD34+细胞中进行了STAT5 RNA干扰，并研究了STAT5下调对正常干/祖细胞区室及白血病对应细胞的影响。STAT5 RNA干扰细胞表现出生长受损，但不影响它们在MS5基质上的CB和AML培养物中的分化。在CB中，有限稀释分析表明祖细胞数量减少了3.9倍。通过长期培养起始细胞（LTC-IC）分析对干细胞进行计数，STAT5下调使平均LTC-IC频率从0.13%降至0.04%，降低了3.25倍。CB CD34+/CD38(-)细胞的单细胞分选实验表明细胞因子驱动的扩增减少了2倍，随后祖细胞减少了2.3倍。在具有组成性STAT5磷酸化的分选CD34+ AML细胞（5/8）中，STAT5 RNA干扰表明在MS5基质上培养6周时细胞数量减少（72%±-17%）且扩增减少（对照培养物中为80±58，而此处为17±15）。总之，我们的数据表明，在正常及白血病造血过程中，原始造血干细胞和祖细胞的维持和扩增均需要STAT5表达。
