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  • 1
    Publication Date: 2012-07-24
    Description: The identification of somatic activating mutations in JAK2 (refs 1-4) and in the thrombopoietin receptor gene (MPL) in most patients with myeloproliferative neoplasm (MPN) led to the clinical development of JAK2 kinase inhibitors. JAK2 inhibitor therapy improves MPN-associated splenomegaly and systemic symptoms but does not significantly decrease or eliminate the MPN clone in most patients with MPN. We therefore sought to characterize mechanisms by which MPN cells persist despite chronic inhibition of JAK2. Here we show that JAK2 inhibitor persistence is associated with reactivation of JAK-STAT signalling and with heterodimerization between activated JAK2 and JAK1 or TYK2, consistent with activation of JAK2 in trans by other JAK kinases. Further, this phenomenon is reversible: JAK2 inhibitor withdrawal is associated with resensitization to JAK2 kinase inhibitors and with reversible changes in JAK2 expression. We saw increased JAK2 heterodimerization and sustained JAK2 activation in cell lines, in murine models and in patients treated with JAK2 inhibitors. RNA interference and pharmacological studies show that JAK2-inhibitor-persistent cells remain dependent on JAK2 protein expression. Consequently, therapies that result in JAK2 degradation retain efficacy in persistent cells and may provide additional benefit to patients with JAK2-dependent malignancies treated with JAK2 inhibitors.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991463/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991463/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koppikar, Priya -- Bhagwat, Neha -- Kilpivaara, Outi -- Manshouri, Taghi -- Adli, Mazhar -- Hricik, Todd -- Liu, Fan -- Saunders, Lindsay M -- Mullally, Ann -- Abdel-Wahab, Omar -- Leung, Laura -- Weinstein, Abby -- Marubayashi, Sachie -- Goel, Aviva -- Gonen, Mithat -- Estrov, Zeev -- Ebert, Benjamin L -- Chiosis, Gabriela -- Nimer, Stephen D -- Bernstein, Bradley E -- Verstovsek, Srdan -- Levine, Ross L -- 1R01CA151949-01/CA/NCI NIH HHS/ -- P30 CA016672/CA/NCI NIH HHS/ -- R01 CA151949/CA/NCI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2012 Sep 6;489(7414):155-9. doi: 10.1038/nature11303.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22820254" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; Disease Models, Animal ; Drug Resistance, Neoplasm/drug effects ; Enzyme Activation/drug effects ; Gene Knockdown Techniques ; Granulocytes/drug effects/enzymology/metabolism ; HSP90 Heat-Shock Proteins/antagonists & inhibitors/metabolism ; Humans ; Janus Kinase 1/biosynthesis/deficiency/genetics/metabolism ; Janus Kinase 2/*antagonists & inhibitors/deficiency/genetics/*metabolism ; Mice ; Myeloproliferative Disorders/*drug therapy/enzymology/metabolism/pathology ; Phosphorylation ; Protein Biosynthesis ; *Protein Multimerization ; RNA Interference ; STAT Transcription Factors/*metabolism ; *Signal Transduction/drug effects ; TYK2 Kinase/biosynthesis/deficiency/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 1995-08-01
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 3
    Publication Date: 1996-10-01
    Description: Most juvenile chronic myelogenous leukemia (JCML) cells have limited long-term proliferative capacity, and only a minority of immature cells give rise to colonies in semisolid cultures. Clonogenic JCML progenitors cannot be maintained in culture because they differentiate, and within a few weeks the leukemic clone is lost. This makes it difficult to identify the cell that initiates and maintains the disease in patients. To determine the proliferative capacity of JCML cells in vivo, bone marrow (BM), peripheral blood, or spleen cells from eight patients with JCML either at diagnosis or during treatment were transplanted into sublethally irradiated severe combined immune deficient (SCID) mice. JCML cells from all patients homed to the murine BM and proliferated extensively in response to exogenous stimulation with granulocyte-macrophage colony-stimulating factor. Within a few weeks, highly engrafted mice became ill and cachectic due to infiltration of leukemic cells and secretion of tumor necrosis factor-alpha. Murine BM, spleen, and liver were infiltrated with leukemic blasts, and typical JCML colony-forming progenitors could be recovered. Kinetic experiments demonstrated that only a small minority of transplanted cells homed to the murine BM, and that these cells initiated and maintained the disease in vivo by extensive proliferation and differentiation. To characterize the cell-surface phenotype of the JCML initiating cell (JCML-IC), JCML blood or spleen cells were fractionated on the basis of CD34/CD38 marker expression and transplanted into SCID mice. Only immature CD34+ cells could initiate the disease, while mature CD34- cells did not engraft. Within the CD34+ compartment, there was enrichment for JCML-ICs by immature cells with a CD34+/CD38- stem-cell-like phenotype. Mice transplanted with more mature CD34+/CD38+ populations that also contained clonogenic JCML progenitors were poorly engrafted. These results indicate that the JCML-IC is an earlier stage of development than clonogenic JCML progenitors. Additional evidence that the JCML-IC has stem-cell properties comes from secondary transplant experiments that test the self-renewal capacity. The JCML-IC from all three patients tested could successfully reinitiate the disease in secondary murine recipients. Thus, we have developed a functional in vivo model that replicates many aspects of human JCML, and have used this model to identify and characterize JCML-ICs and their stem-cell properties.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 4
    Publication Date: 1987-11-01
    Description: At diagnosis peripheral blood (PB) or bone marrow from patients with juvenile chronic myelogenous leukemia (JCML) have shown two reproducible abnormalities when studied in cell culture: impaired growth of normal hematopoietic progenitors and excessive proliferation of malignant monocyte-macrophage elements. We used these findings to assess quality of treatment response by serially studying PB specimens from four JCML patients (patients 5, 7, 8, and 9) in complete chemotherapy-induced remission. PB readily yielded high numbers of monocyte-macrophage colonies in CFU-C and CFU-GEMM assays when cultured in early remission, and the colonies were cytogenetically proven to have arisen from a malignant clone in patient 9. When studied later in remission, the abnormal cell proliferation persisted in three of the four patients, but in patient 8 PB colony growth resembled controls. Similarly, when PB from patient 8 was studied in liquid culture without using added growth factor, cell proliferation declined identical to controls, whereas PB from the other three patients showed exuberant growth of monocyte-macrophage elements. Patient 8 successfully completed therapy and has been in a long-term, disease-free remission. The other three had recurrent, ultimately fatal disease. The cell cultures have allowed detection of residual abnormal cells that circulate in PB of JCML patients in remission. Although patient numbers were small because of the rarity of JCML, the data suggested that persistence of leukemia cells in these patients had a bearing on clinical outcome.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 5
    Publication Date: 1986-06-01
    Description: To analyze the role of T lymphocytes in human erythropoiesis, we evaluated the effect of recombinant interleukin 2 (IL 2) on marrow CFU- E and BFU-E colony formation in vitro. IL 2 resulted in an increase in CFU-E and BFU-E colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody to the IL 2 receptor. Moreover, anti-Tac on its own resulted in an overall decrease in colony numbers. Depletion of marrow adherent cells did not alter the effect of either IL 2 or anti-Tac on colony growth. Following the removal of marrow T lymphocytes, CFU-E and BFU-E colony formation proceeded normally; however, the effects of IL 2 and anti-Tac were markedly diminished. Readdition of T lymphocytes to the cultures restored the IL 2 effect. Although T lymphocytes were not themselves essential for in vitro erythropoiesis, our studies suggest that IL 2 and IL 2-responsive T cells can regulate both early and mature stages of erythroid differentiation.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 6
    Publication Date: 1986-05-01
    Description: To characterize juvenile chronic myelogenous leukemia (JCML), the proliferative properties of bone marrow (BM) and peripheral blood (PB) cells from nine patients were studied using assays for CFU-C and CFU- GEMM and liquid cultures. All specimens showed two reproducible abnormalities: impaired growth of normal hematopoietic progenitors and excessive proliferation of monocyte-macrophage colonies in the absence of exogenous colony-stimulating activity (CSA). Cytogenetic studies in one patient indicated that the CFU-C were malignant because BM cells at diagnosis and monocyte-macrophage colonies showed an abnormal karyotype, whereas PB lymphocytes did not. In contrast to JCML, PB from six adults with Philadelphia (Ph1) chromosome-positive chronic myelogenous leukemia (Ph1 + CML) yielded CSA-dependent CFU-C colonies which were composed of granulocytes, macrophages, or both, as well as exuberant growth of BFU-E colonies. Co-cultures of JCML BM adherent or nonadherent cells with normal BM resulted in suppression of normal hematopoietic colony formation. Supernatant from JCML adherent cells in liquid culture or plasma from newly diagnosed untreated JCML patients also suppressed control BM colony growth in a dose-dependent manner. These findings confirm that JCML is a malignant disorder of monocytic lineage and suggest that the mechanism of hematopoietic failure in JCML is mediated by an inhibitory monokine secreted by malignant JCML cells.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
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  • 7
    Publication Date: 1987-04-01
    Description: The effect of recombinant interleukin 2 (IL2) on marrow CFU-C colony formation was evaluated to define the role for T lymphocytes in human marrow granulopoiesis. The colony-stimulating factor (CSA) used in our experiments was found to contain IL2. IL2 depletion from CSA resulted in a reduction in CFU-C colony proliferation. Addition of exogenous IL2 caused an increase in CFU-C colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody (MoAb) to the IL2 receptor. Moreover, anti-Tac in the absence of exogenous IL2 resulted in an overall decrease in colony numbers. Depletion of either adherent cells or T lymphocytes abolished the effect of IL2 and anti-Tac on colony growth. In the presence of IL2, re- addition of T lymphocytes to the T-depleted marrow or adherent cells to adherent cell-depleted marrow resulted in a significant increase in CFU- C colony numbers, whereas no significant effect was found when IL2- depleted CSA was used. Although T lymphocytes were not themselves essential for CFU-C colony growth, our studies indicate that IL2 and IL2-responsive T cells can regulate in vitro granulopoiesis.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 8
    Publication Date: 1991-09-15
    Description: In this study, we investigated the role of interleukin-1 beta (IL-1 beta) in the malignant evolution of chronic myelogenous leukemia (CML) and the functional activity of IL-1 inhibitors. Bone marrow (BM) and peripheral blood (PB) low-density cells from 38 CML patients were studied in the colony-forming unit-granulocyte, erythrocyte, monocyte, megakaryocyte colony culture assay. Samples from patients with early stage, interferon-alpha (IFN)-sensitive disease formed hematopoietic colonies in the presence of fetal calf serum (FCS), erythropoietin (Epo), and one of the following: granulocyte-macrophage colony- stimulating factor (10 ng/mL), IL-3 (15 ng/mL), both, or phytohemagglutinin-conditioned medium. The addition of IL-1 beta augmented IFN-sensitive CML colony growth in a dose-dependent manner at concentrations of 10 to 100 U/mL. In sharp contrast, addition of the above growth factors did not augment the colony growth-promoting effect of FCS and Epo in samples from IFN-resistant patients; further, adherent cell fractionation or T-lymphocyte depletion attenuated the “autonomous” colony growth. Lysates of 2.5 x 10(7) low-density cells from each of six IFN-resistant and six IFN-sensitive CML patients and three normal volunteers were tested for intrinsic IL-1 beta content in an enzyme-linked immunosorbent assay and yielded a mean of 610 pg, 54.6 pg, and 49.4 pg of IL-1 beta, respectively (P less than .045). Interestingly, both soluble IL-1 receptors (sIL-1R) and IL-1 receptor antagonist (IL-1RA) at concentrations of 5 to 100 ng/mL (sIL-1R) and 10 to 500 ng/mL (IL-1RA) inhibited CML colony growth in a dose-dependent fashion, with maximal inhibition of 64% and 65%, respectively. A similar effect was noted with the use of anti-IL-1 beta neutralizing antibodies. These data implicate IL-1 beta in CML disease progression and suggest that the inhibitory effects of molecules such as sIL-1R and IL-1RA could conceivably be the basis of a novel therapeutic strategy against this disorder.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 9
    Publication Date: 1986-06-01
    Description: To analyze the role of T lymphocytes in human erythropoiesis, we evaluated the effect of recombinant interleukin 2 (IL 2) on marrow CFU- E and BFU-E colony formation in vitro. IL 2 resulted in an increase in CFU-E and BFU-E colony numbers in a dose-dependent manner. This increase could be prevented by anti-Tac, a monoclonal antibody to the IL 2 receptor. Moreover, anti-Tac on its own resulted in an overall decrease in colony numbers. Depletion of marrow adherent cells did not alter the effect of either IL 2 or anti-Tac on colony growth. Following the removal of marrow T lymphocytes, CFU-E and BFU-E colony formation proceeded normally; however, the effects of IL 2 and anti-Tac were markedly diminished. Readdition of T lymphocytes to the cultures restored the IL 2 effect. Although T lymphocytes were not themselves essential for in vitro erythropoiesis, our studies suggest that IL 2 and IL 2-responsive T cells can regulate both early and mature stages of erythroid differentiation.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
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  • 10
    Publication Date: 1987-03-01
    Description: A six week old infant with acute leukemia failed to attain remission with chemotherapy. Because we previously demonstrated that the iron chelator deferoxamine (DFO) has antiproliferative properties and modulatory effects on cell differentiation, a protocol was designed for in vitro study and for clinical use in the patient. At diagnosis, blast cells were morphologically undifferentiated, had nondiagnostic cytochemistry, showed an abnormal karyotype (t[4;11]), expressed markers of B cell lineage, and demonstrated C mu gene rearrangement. Tissue culture of marrow or blood cells yielded colonies of leukemic blasts. Increasing concentrations of DFO produced a dose-dependent suppression of patient's blast colony growth in vitro, and blasts within colonies showed a marked change in surface antigen expression from lymphoid to myelomonocytic markers, became monocytic in appearance, and developed intense staining for nonspecific esterase. When DFO was given intravenously to the patient as a single agent for 48 hours, blasts no longer expressed lymphoid antigens and became strongly positive for myelomonocytic markers, identical to the in vitro findings. Intravenous DFO halted rising peripheral blood blast cell numbers and allowed a several-fold increase in normal hematopoietic progenitor colony growth. When combined with low-dose cytosine arabinoside in the treatment protocol, DFO caused striking leukemic cytoreduction. Our findings indicate that DFO has antileukemic properties by virtue of its effects on proliferation and differentiation, and they prompt further experimental and clinical studies with this agent.
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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