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1.  Positive feedback between NF-κB and TNF-α promotes leukemia-initiating cell capacity 
Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy that originates from leukemia-initiating cells (LICs). The identification of common mechanisms underlying LIC development will be important in establishing broadly effective therapeutics for AML. Constitutive NF-κB pathway activation has been reported in different types of AML; however, the mechanism of NF-κB activation and its importance in leukemia progression are poorly understood. Here, we analyzed myeloid leukemia mouse models to assess NF-κB activity in AML LICs. We found that LICs, but not normal hematopoietic stem cells or non-LIC fractions within leukemia cells, exhibited constitutive NF-κB activity. This activity was maintained through autocrine TNF-α secretion, which formed an NF-κB/TNF-α positive feedback loop. LICs had increased levels of active proteasome machinery, which promoted the degradation of IκBα and further supported NF-κB activity. Pharmacological inhibition of the proteasome complex markedly suppressed leukemia progression in vivo. Conversely, enhanced activation of NF-κB signaling expanded LIC frequency within leukemia cell populations. We also demonstrated a strong correlation between NF-κB activity and TNF-α secretion in human AML samples. Our findings indicate that NF-κB/TNF-α signaling in LICs contributes to leukemia progression and provide a widely applicable approach for targeting LICs.
doi:10.1172/JCI68101
PMCID: PMC3904603  PMID: 24382349
2.  Evi1 is essential for hematopoietic stem cell self-renewal, and its expression marks hematopoietic cells with long-term multilineage repopulating activity 
The Journal of Experimental Medicine  2011;208(12):2403-2416.
A new mouse in which an IRES-GFP cassette is knocked-in to the Evi1 locus reveals that HSC long-term multilineage repopulating activity specifically segregates with expression of the Evi1 transcription factor.
Ecotropic viral integration site 1 (Evi1), a transcription factor of the SET/PR domain protein family, is essential for the maintenance of hematopoietic stem cells (HSCs) in mice and is overexpressed in several myeloid malignancies. Here, we generate reporter mice in which an internal ribosome entry site (IRES)-GFP cassette is knocked-in to the Evi1 locus. Using these mice, we find that Evi1 is predominantly expressed in long-term HSCs (LT-HSCs) in adult bone marrow, and in the hematopoietic stem/progenitor fraction in the aorta-gonad-mesonephros, placenta, and fetal liver of embryos. In both fetal and adult hematopoietic systems, Evi1 expression marks cells with long-term multilineage repopulating activity. When combined with conventional HSC surface markers, sorting according to Evi1 expression markedly enhances purification of cells with HSC activity. Evi1 heterozygosity leads to marked impairment of the self-renewal capacity of LT-HSCs, whereas overexpression of Evi1 suppresses differentiation and boosts self-renewal activity. Reintroduction of Evi1, but not Mds1-Evi1, rescues the HSC defects caused by Evi1 heterozygosity. Thus, in addition to documenting a specific relationship between Evi1 expression and HSC self-renewal activity, these findings highlight the utility of Evi1-IRES-GFP reporter mice for the identification and sorting of functional HSCs.
doi:10.1084/jem.20110447
PMCID: PMC3256960  PMID: 22084405
3.  Comparison of temporal changes in psychological distress after hematopoietic stem cell transplantation among the underlying diseases of Japanese adult patients 
Background
Although hematopoietic stem cell transplantation (HSCT) can potentially cure some hematological malignancies, patients who undergo HSCT experience psychological distress. However, there have been few studies on the short-term influence of HSCT on psychological distress.
Methods
The subjects were 71 patients with hematological malignancies who underwent HSCT: 33 with acute leukemia, 19 with chronic leukemia, nine with myelodysplastic syndrome, and 10 with malignant lymphoma. Psychological distress was assessed prior to HSCT and on the seventh day after HSCT using the Profile of Mood States (POMS).
Results
With regard to Anger-Hostility, the interaction of time (pre- and post-HSCT) and group (the four groups) was significant in male patients (p = 0.04), but not in female patients. With regard to the other subscales of POMS, there was no significant main effect or interaction in male or female patients.
Conclusion
It may be important to provide psychological support to patients throughout the period of HSCT in consideration of differences in mood changes associated with the underlying disease and patient sex in order to provide efficient psychiatric intervention for both better psychiatric and survival outcomes.
doi:10.1186/1751-0759-2-24
PMCID: PMC2603014  PMID: 19025589
4.  Binding of Delta1, Jagged1, and Jagged2 to Notch2 Rapidly Induces Cleavage, Nuclear Translocation, and Hyperphosphorylation of Notch2 
Molecular and Cellular Biology  2000;20(18):6913-6922.
Delta1, Jagged1, and Jagged2, commonly designated Delta/Serrate/LAG-2 (DSL) proteins, are known to be ligands for Notch1. However, it has been less understood whether they are ligands for Notch receptors other than Notch1. Meanwhile, ligand-induced cleavage and nuclear translocation of the Notch protein are considered to be fundamental for Notch signaling, yet direct observation of the behavior of the Notch molecule after ligand binding, including cleavage and nuclear translocation, has been lacking. In this report, we investigated these issues for Notch2. All of the three DSL proteins bound to endogenous Notch2 on the surface of BaF3 cells, although characteristics of Jagged2 for binding to Notch2 apparently differed from that of Delta1 and Jagged1. After binding, the three DSL proteins induced cleavage of the membrane-spanning subunit of Notch2 (Notch2TM), which occurred within 15 min. In a simultaneous time course, the cleaved fragment of Notch2TM was translocated into the nucleus. Interestingly, the cleaved Notch2 fragment was hyperphosphorylated also in a time-dependent manner. Finally, binding of DSL proteins to Notch2 also activated the transcription of reporter genes driven by the RBP-Jκ-responsive promoter. Together, these data indicate that all of these DSL proteins function as ligands for Notch2. Moreover, the findings of rapid cleavage, nuclear translocation, and phosphorylation of Notch2 after ligand binding facilitate the understanding of the Notch signaling.
PMCID: PMC88767  PMID: 10958687

Results 1-4 (4)