| 1. |
- Tang, Yan-juan, et al.
(författare)
-
Coexpression of hyperactivated AKT1 with additional genes activated in leukemia drives hematopoietic progenitor cells to cell cycle block and apoptosis
- 2015
-
Ingår i: Experimental Hematology. - : Elsevier. - 0301-472X .- 1873-2399. ; 43:7, s. 554-564
-
Tidskriftsartikel (refereegranskat)abstract
- The phosphatidylinositol 3-kinase/AKT pathway is an integral component of signaling involved in the development of many cancers, including myeloid leukemias such as chronic myeloid leukemia and acute myeloid leukemia (AML). Increased AKT1 activity is frequently seen in AML patients, providing leukemic cells with growth and survival promoting signals. An important aspect of AKT1 function is its involvement in cellular metabolism and energy production. Under some circumstances, strong activation of AKT1 increases oxidative stress, which can cause apoptosis when cells progressively build up excess free radicals. This has been described in hematopoietic cells overexpressing activated AKT1; however, whether this is true in cells coexpressing other genetic events involved in leukemia is not known. This prompted us to investigate the effect of constitutively active AKT1 (myristoylated AKT1) in hematopoietic progenitor cells expressing constitutively active signal transducer and activator of transcription 5, Fms-related tyrosine kinase 3-internal tandem duplication, or antiapoptotic B-cell lymphoma 2. Surprisingly, myristoylated AKT1 was incompatible with proliferation driven by both signal transducer and activator of transcription 5 and Fms-related tyrosine kinase 3-internal tandem duplication, which triggered cell cycle block and apoptosis. Moreover, transplantable cells of B-cell lymphoma 2-transgenic mice were impaired in their engraftment ability to recipient mice when expressing hyperactivated AKT1. This Was linked to AKT1-mediated proapoptotic functions and not to impairment in homing to the bone marrow. Although cells expressing hyperactivated AKT1 displayed higher levels of reactive oxygen species both in vitro and in vivo, the addition of the antioxidant N-acetyl-L-cysteine significantly reduced apoptosis. Taken together, the results indicate that constitutive AKT1 activity is incompatible with growth- and survival-promoting ability of other activated genes in AML. Copyright (C) 2015 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc.
|
|
| 2. |
- Cheng, Min, et al.
(författare)
-
Distinct and overlapping patterns of cytokine regulation of thymic and bone marrow-derived NK cell development.
- 2009
-
Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:3, s. 1460-1468
-
Tidskriftsartikel (refereegranskat)abstract
- Although bone marrow (BM) represents the main site for postnatal NK cell development, recently a distinct thymic-dependent NK cell pathway was identified. These studies were designed to investigate the role of cytokines in regulation of thymic NK cells and to compare with established regulatory pathways of BM-dependent NK cell compartment. The common cytokine receptor gamma-chain (Il2rg) essential for IL-15-induced signaling, and FMS-like tyrosine kinase 3 (FLT3) receptor ligand (Flt3l) were previously identified as important regulatory pathways of the BM NK cell compartment based on lack of function studies in mice, however their complementary action remains unknown. By investigating mice double-deficient in Il2rg and Flt3l (Flt3l(-/-) Il2rg(-/-)), we demonstrate that FLT3L is important for IL2Rg-independent maintenance of both immature BM as well as peripheral NK cells. In contrast to IL-7, which is dispensable for BM but important for thymic NK cells, IL-15 has a direct and important role in both thymic and BM NK cell compartments. Although thymic NK cells were not affected in Flt3l(-/-) mice, Flt3l(-/-)Il2rg(-/-) mice lacked detectable thymic NK cells, suggesting that FLT3L is also important for IL-2Rg-independent maintenance of thymic NK cells. Thus, IL-2Rg cytokines and FLT3L play complementary roles and are indispensable for homeostasis of both BM and thymic dependent NK cell development, suggesting that the cytokine pathways crucial for these two distinct NK cell pathways are largely overlapping.
|
|
| 3. |
- Hamzic, Namik, et al.
(författare)
-
Interleukin-6 produced by non-hematopoietic cells mediates the lipopolysaccharide-induced febrile response
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Interleukin-6 (IL-6) is critical for the lipopolysaccharide (LPS)-induced febrile response. However, the exact source(s) of IL-6 involved in regulating the LPS-elicited fever is still to be identified. One known source of IL-6 is hematopoietic cells, such as monocytes. To clarify the contribution of hematopoietically derived IL-6 to fever, we created chimeric mice expressing IL-6 either in cells of hematopoietic or, conversely, in cells of non-hematopoietic origin. This was performed by extinguishing hematopoetic cells in wild-type (WT) or IL-6 knockout (IL-6 KO) mice by whole-body irradiation and transplanting them with new stem cells. Mice lacking IL-6 in hematopoietic cells displayed normal fever to LPS and were found to have similar levels of IL-6 in the cerebrospinal fluid (CSF) and in plasma as well as similar expression of the IL-6 gene in the brain as WT mice. In contrast, IL-6 KO mice, with intact IL-6 production in cells of hematopoietic origin, only showed a minor elevation of the body temperature after peripheral LPS injection. While they displayed significantly elevated levels of IL-6 both in plasma and CSF compared with control mice, the increase was modest compared with that seen in LPS injected mice on WT background, the latter being approximately 20 times larger in magnitude. These results suggest that IL-6 of nonhematopoietic origin is the main source of IL-6 in LPS-induced fever, and that IL-6 produced by hematopoietic cells only plays a minor role.
|
|
| 4. |
- Nordigården, Amanda, et al.
(författare)
-
A comparative study of various FLT3-ITDs in relation to function and signaling
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Internal tandem duplications (ITD) in the FMS like tyrosine kinase (FLT3) receptor are one of the most common classes of mutations in acute myeloid leukemia (AML), which presence indicates a poor prognosis. Lengths of FLT3-ITD mutations found in patients can vary from 3 up to hundreds of nucleotides and may be located either in the juxtamembrane domain or the tyrosine kinase-1 domain (TKD1). There are contradicting opinions whether the length of the ITD has an impact on the clinical situation and whether tyrosines duplicated are of any significance for oncogenic signaling. Considering the substantial differences in lengths as well as the variability of start and end points of ITDs, we have performed a study of various FLT3-ITD mutations isolated from AML-patients. The ITD region from leukemic blasts of nine AML patients were sequenced and cloned by PCR into the human wildtype FLT3 cDNA, inserted to a retroviral GFP-containing vector. The hematopoietic progenitor cell line FDC-P1 was used to elucidate the impact of the different ITDs on growth, survival, signal transduction, and resistance to the FLT3-targeting inhibitor PKC412. Interestingly, the shortest and the longest ITDs were two of the three mutations that lead to the poorest survival of cells upon cytokine-deprivation, indicating that ITD size may not influence the transforming potential of cells. Furthermore one ITD that starts and ends relatively 3´ positioned, and comprises the 5´-part of the TKD1 showed both a survival advantage in starvation experiments and a significantly higher proliferation potential in comparison to several other mutations. Two other ITDs spanning this region, but with more 5´localized starting points, displayed less sensitivity to PKC412 treatment. However, this was not associated to STAT5 activity and MCL-1 upregulation as suggested by previous report. Taken together, this study suggests that different FLT3-ITD mutations may induce distinct signaling and response towards FLT3 targeting drugs, dependent of FLT3-ITD composition and not length.
|
|
| 5. |
- Tang, Yanjuan, et al.
(författare)
-
Emergence of NK cell progenitors and functionally competent NK cell lineage subsets in the early mouse embryo.
- 2012
-
Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 120:1, s. 63-75
-
Tidskriftsartikel (refereegranskat)abstract
- The earliest stages of natural killer (NK) cell development are not well characterized. In this study, we investigated in different fetal hematopoietic tissues how NK cell progenitors and their mature NK cell progeny emerge and expand during fetal development. Here we demonstrate, for the first time, that the counterpart of adult bone marrow Lin(-)CD122(+)NK1.1(-)DX5(-) NK cell progenitor (NKP) emerges in the fetal liver at embryonic day (E) 13.5. Following NKP expansion, immature NK cells emerge at day E14.5 in the liver and E15.5 in the spleen. Thymic NK cells arise at day E15.5, while functionally competent cytotoxic NK cells were present in the liver and spleen at day E16.5 and E17.5, respectively. Fetal NKPs failed to produce B and myeloid cells, but sustained combined NK and T lineage potential at the single cell level. NKPs were also found in the fetal blood, spleen and thymus. These findings demonstrate the emergence and expansion of bipotent NK/T cell progenitor during fetal and adult lymphopoiesis, further supporting that NK/T lineage restriction is taking place prethymically. Uncovering the earliest NK cell developmental stages will provide important clues helping to understand the origin of diverse NK cell subsets, their progenitors and key regulators.
|
|
| 6. |
- Tang, Yanjuan, et al.
(författare)
-
Hyperactivated AKT is incompatible with survival when coexpressed with additional oncogenes and drives hematopoietic stem and progenitor cells to cell cycle inhibition and apoptosis
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The PI3K-AKT signaling pathway plays an important role in cell growth and metabolism. Increased AKT activity is frequently seen in patients with acute myeloid leukemia (AML), providing leukemic cells with both growth-promoting and survival signals involved in the transformation process. In AML up to 30% of all patients carry activating mutations in the tyrosine kinase receptor FLT3, leading to activation of the PI3K/AKT pathway as well as STAT5. Here, we investigated the effect of hyperactivated AKT (myristylated AKT) by retroviral transfer to hematopoietic progenitor cells coexpressing STAT5, FLT3-ITD, or antiapoptotic Bcl-2. AKT was unable to relieve cytokine-dependence. Surprisingly, uncontrolled AKT activity was linked to accumulation of cells in the G0 stage of the cell cycle and increased cell numbers became apoptotic. Hyperactivated AKT was incompatible with STAT5-driven proliferation and triggered apoptosis. The same was true also in FLT3-ITDexpressing progenitor cells of transgenic mice. Transplantable hematopoietic stem cells of wildtype and Bcl-2 transgenic mice were impaired in their engraftment ability to recipient mice when expressing hyperactivated AKT. This was linked to AKT-mediated pro-apoptotic functions and not due to effects on homing or migration. Cells expressing hyperactivated AKT displayed higher levels of reactive oxygen species. However, the addition of the antioxidant N-acetyl-L-lysine significantly reduced apoptosis. Taken together, the results indicate that constitutive AKT activity is incompatible with the growth- and survivalpromoting ability of FLT3-ITD and its downstream targets. These findings may provide a novel tool to intervene with AKT activity in leukemia.
|
|
