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Blood May 2005Mutations in the ELA2 gene encoding neutrophil elastase (NE) are present in most patients with severe congenital neutropenia (SCN). However, the mechanisms by which...
Aberrant subcellular targeting of the G185R neutrophil elastase mutant associated with severe congenital neutropenia induces premature apoptosis of differentiating promyelocytes.
Mutations in the ELA2 gene encoding neutrophil elastase (NE) are present in most patients with severe congenital neutropenia (SCN). However, the mechanisms by which these mutations cause neutropenia remain unknown. To investigate the effects of mutant NE expression on granulopoiesis, we used the HL-60 promyelocytic cell line retrovirally transduced with the G185R NE mutant that is associated with a severe SCN phenotype. We show that the mutant enzyme accelerates apoptosis of differentiating but not of proliferating cells. Using metabolic labeling, confocal immunofluorescence microscopy, and immunoblot analysis of subcellular fractions, we also demonstrate that the G185R mutant is abnormally processed and localizes predominantly to the nuclear and plasma membranes rather than to the cytoplasmic compartment observed with the wild-type (WT) enzyme. Expression of the G185R mutant appeared to alter the subcellular distribution and expression of adaptor protein 3 (AP3), which traffics proteins from the trans-Golgi apparatus to the endosome. These observations provide further insight into potential mechanisms by which NE mutations cause neutropenia and suggest that abnormal protein trafficking and accelerated apoptosis of differentiating myeloid cells contribute to the severe SCN phenotype resulting from the G185R mutation.
Topics: Adaptor Protein Complex 3; Apoptosis; Cell Compartmentation; Cell Differentiation; Cell Proliferation; Granulocyte Precursor Cells; HL-60 Cells; Humans; Leukocyte Elastase; Mutation, Missense; Neutropenia; Protein Transport; Transduction, Genetic
PubMed: 15657182
DOI: 10.1182/blood-2004-07-2618 -
European Journal of Haematology Jun 2005Patients with hyperleukocytic leukaemia were graded according to the severity of symptoms possibly caused by leukostasis to evaluate the effectiveness of therapy and to... (Comparative Study)
Comparative Study
OBJECTIVE
Patients with hyperleukocytic leukaemia were graded according to the severity of symptoms possibly caused by leukostasis to evaluate the effectiveness of therapy and to test the relative contribution of blast type and count of blasts and promyelocytes in the development of leukostasis syndrome.
METHODS
Ninety-five patients (59 male, 36 female, median age 52 yr) with hyperleukocytic leukaemia [leukocytes above 50 x 10(9)/L, 48 acute myeloid leukaemia (AML), 31 chronic myeloid leukaemia (CML), 13 acute lymphoblastic leukaemia (ALL), three chronic myelomonocytic leukaemia (CMML)] were grouped according to the presence or absence and severity of neurologic, pulmonary and other symptoms into four categories (no, possible, probable and highly probable leukostasis syndrome). Age, white blood count (WBC), haemoglobin, blast count and total of blasts plus promyelocytes of these groups were compared by Mann-Whitney U-test.
RESULTS
Patients with myeloid leukaemia (AML M1/M2, CML) which scored as highly probable leukostasis showed significantly higher WBC (P = 0.011), lower haemoglobin (P = 0.004), higher peripheral blast counts (P = 0.004) and higher total of peripheral blasts plus promyelocytes (P < 0.001) compared with the lower probability groups. In leukaemia involving the monocytic lineage (AML M4/M5, CMML) no significant differences were found in any of these factors between patients with highly probable leukostasis and the other patients.
CONCLUSIONS
Our results show that a four-stage clinical grading scale is a valuable tool for analysing hyperleukocytic patient populations and evaluate the effectiveness of therapy more precisely. We further demonstrate that the mechanisms of leukostasis are different in myeloid leukaemia as compared with leukaemia with involvement of the monocytic lineage.
Topics: Adolescent; Adult; Age Factors; Aged; Aged, 80 and over; Blast Crisis; Cell Lineage; Female; Granulocyte Precursor Cells; Hemoglobins; Humans; Leukemia, Myeloid; Leukocyte Count; Male; Middle Aged; Myelodysplastic Syndromes
PubMed: 15876254
DOI: 10.1111/j.1600-0609.2005.00421.x -
Nature Nov 1963
Topics: Animals; Bone Marrow; Cell Division; DNA; Granulocyte Precursor Cells; Guinea Pigs; Leukocytes; Mitosis; Research; Thymidine; Tritium
PubMed: 14109985
DOI: 10.1038/200712a0 -
Experimental Cell Research Jan 2010Vav1 plays an important role in the all-trans retinoic acid (ATRA)-induced completion of the differentiation program of acute promyelocytic leukemia (APL)-derived cells,...
Vav1 plays an important role in the all-trans retinoic acid (ATRA)-induced completion of the differentiation program of acute promyelocytic leukemia (APL)-derived cells, in which it strengthens the drug effects and is involved in the regulation of maturation-related proteins, such as the CD11b surface antigen. In both myeloid and lymphoid cells, accumulating data attribute to the multidomain protein Vav1 a functional relevance in the control of gene expression, by direct interaction with chromatin remodeling and/or transcriptional proteins. The present study provides evidence that, in the APL-derived NB4 cell line, Vav1 and the transcription factor PU.1 cooperate in regulating the ATRA-induced CD11b expression. Both chromatin immunoprecipitation (ChIP) experiments and electrophoretic mobility shift assays (EMSA) indicate that Vav1 and PU.1 are recruited to CD11b promoter. Even if the two proteins may participate in diverse protein/DNA complexes, the amounts of complexes including PU.1 seem to be dependent on the interaction of this transcription factor with tyrosine-phosphorylated Vav1. The reported data suggest that the ATRA-induced increase of Vav1 expression and tyrosine phosphorylation may be involved in recruiting PU.1 to its consensus sequence on the CD11b promoter and, ultimately, in regulating CD11b expression during the late stages of neutrophil differentiation of APL-derived promyelocytes.
Topics: CD11b Antigen; Cell Differentiation; Cell Line, Tumor; Cell Nucleus; Chromatin Immunoprecipitation; DNA; Electrophoretic Mobility Shift Assay; Gene Expression Regulation, Neoplastic; Granulocyte Precursor Cells; Humans; Intracellular Signaling Peptides and Proteins; Leukemia, Promyelocytic, Acute; Neutrophils; Phosphorylation; Promoter Regions, Genetic; Protein Binding; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-vav; RNA, Small Interfering; Stilbenes; Syk Kinase; Trans-Activators; Tretinoin
PubMed: 19747912
DOI: 10.1016/j.yexcr.2009.09.004 -
Blood Cancer Discovery May 2024In many cancers, mortality is associated with the emergence of relapse with multidrug resistance (MDR). Thus far, the investigation of cancer relapse mechanisms has...
UNLABELLED
In many cancers, mortality is associated with the emergence of relapse with multidrug resistance (MDR). Thus far, the investigation of cancer relapse mechanisms has largely focused on acquired genetic mutations. Using acute myeloid leukemia (AML) patient-derived xenografts (PDX), we systematically elucidated a basis of MDR and identified drug sensitivity in relapsed AML. We derived pharmacologic sensitivity for 22 AML PDX models using dynamic BH3 profiling (DBP), together with genomics and transcriptomics. Using in vivo acquired resistant PDXs, we found that resistance to unrelated, narrowly targeted agents in distinct PDXs was accompanied by broad resistance to drugs with disparate mechanisms. Moreover, baseline mitochondrial apoptotic priming was consistently reduced regardless of the class of drug-inducing selection. By applying DBP, we identified drugs showing effective in vivo activity in resistant models. This study implies evasion of apoptosis drives drug resistance and demonstrates the feasibility of the DBP approach to identify active drugs for patients with relapsed AML.
SIGNIFICANCE
Acquired resistance to targeted therapy remains challenging in AML. We found that reduction in mitochondrial priming and common transcriptomic signatures was a conserved mechanism of acquired resistance across different drug classes in vivo. Drugs active in vivo can be identified even in the multidrug resistant state by DBP.
Topics: Leukemia, Myeloid, Acute; Humans; Apoptosis; Animals; Mice; Drug Resistance, Neoplasm; Drug Resistance, Multiple; Xenograft Model Antitumor Assays; Granulocyte Precursor Cells; Antineoplastic Agents
PubMed: 38442309
DOI: 10.1158/2643-3230.BCD-24-0001 -
Zhongguo Shi Yan Xue Ye Xue Za Zhi Aug 2012This study was purpose to investigate the immunophenotype of leukemia promyelocytes (LP) and its significance through retrospective analysis of LP immunophenotype and...
This study was purpose to investigate the immunophenotype of leukemia promyelocytes (LP) and its significance through retrospective analysis of LP immunophenotype and data in new diagnosis of patients with acute promyelocytic leukemia (APL). The immunophenotype of leukemia cells in 71 APL patients was analyzed by means of 6 color immunotyping. The results indicated that MPO, CD33 and CD13 were consistently expressed in leukemia cells of all APL cases with highest average percentages (> 88%) of positive cells among all studied markers. CD117 was found to be positive in 50.7%, and its average percentage of positive cells was 52.5%. Leukemia cells in about 10% cases expressed CD15 weakly, and its average percentage of positive cells was 42.5%. CD34 and HLA-DR showed decreased expressions in a small number of cases and were negative in the others. CD2 and CD56 were weakly expressed in nearly 25% APL cases, and the average percentage of positive cells were 39.3% and 42.3%, respectively. Thereby, it is of the opinion that the typical immunophenotype is characterized by MPO(+)CD13(+)CD33(+)CD117(±)CD15(±)CD34(-)HLA-DR(-) in APL. CD2 and CD56 were expressed significantly higher in CD34(+) or HLA-DR(+) group (including CD34(+) HLA-DR(+), CD34(+) HLA-DR(-) and CD34(-)HLA-DR(+)) than in CD34(-) and HLA-DR(-) group. Significant differences were also found in WBC and platelet counts, percentage of peripheral blood leukemic promyelocytes and the expression of CD13 among CD15 < 10%, 10% < CD15 < 20% and CD15 > 20% groups. It is concluded that the APL has a characteristic immunophenotypic profile, flow cytometric immunophenotyping may be considered as a useful tool for rapid recognition of APL and also may be considered to have an important significance for analysing origin of leukemic cells and clinical outcome of patients.
Topics: Adolescent; Adult; Aged; Child; Child, Preschool; Female; Granulocyte Precursor Cells; Humans; Immunity, Cellular; Immunophenotyping; Leukemia, Promyelocytic, Acute; Male; Middle Aged; Young Adult
PubMed: 22931633
DOI: No ID Found -
Blood May 2016
Topics: Aged; Antigens, CD; Blood Cell Count; Chromatin; Dyspnea; Fatigue; Granulocyte Precursor Cells; Humans; Leukemia, Myeloid, Acute; Male; Pancytopenia
PubMed: 28092888
DOI: 10.1182/blood-2016-02-698506 -
Journal of Proteomics Dec 2011Vav1 is a key molecule in the ATRA-induced acquisition of a mature phenotype by tumoral myeloid precursors. Since ATRA acts throughout events that require extensive...
Vav1 is a key molecule in the ATRA-induced acquisition of a mature phenotype by tumoral myeloid precursors. Since ATRA acts throughout events that require extensive changes of nuclear architecture and activity and considering that Vav1 accumulates inside the nuclear compartment of differentiating APL-derived cells, the possible role of this protein in modulating the nuclear proteome was investigated. Membrane-depleted nuclei purified from NB4 cells induced to differentiate with ATRA in the presence of forcedly down-modulated Vav1 were subjected to 2D-DIGE followed by mass spectra analysis. The obtained data demonstrated that, in NB4 cells treated with ATRA, Vav1 is involved in determining the nuclear amount of proteins involved in molecular complexes with DNA and may participate to RNA processing by carrying in the nucleus molecules involved in modulating mRNA production and stability, like hnRNPs and SR proteins. Our results provide the first evidence that, at least in maturation of tumoral myeloid precursors, Vav1 is part of interconnected networks of functionally related proteins ended to regulate different aspects of gene expression. Since defects in mRNA processing are common in tumor development, our data suggest that Vav1 is a potential target molecule for developing new anti-cancer strategies.
Topics: Cell Differentiation; Cell Nucleus; Granulocyte Precursor Cells; Humans; Nuclear Proteins; Proto-Oncogene Proteins c-vav; RNA; RNA Interference; Tretinoin; Two-Dimensional Difference Gel Electrophoresis
PubMed: 21856460
DOI: 10.1016/j.jprot.2011.08.005 -
Haematologica Nov 2008The classification of myelodysplastic syndromes is based on the morphological criteria proposed by the French-American-British (FAB) and World Health Organization (WHO)...
Diagnosis and classification of myelodysplastic syndrome: International Working Group on Morphology of myelodysplastic syndrome (IWGM-MDS) consensus proposals for the definition and enumeration of myeloblasts and ring sideroblasts.
The classification of myelodysplastic syndromes is based on the morphological criteria proposed by the French-American-British (FAB) and World Health Organization (WHO) groups. Accurate enumeration of blast cells, although essential for diagnosis of myelodysplastic syndrome and for assignment to prognostic groups, is often difficult, due to imprecise criteria for the morphological definition of blasts and promyelocytes. An International Working Group on Morphology of Myelodysplastic Syndrome (IWGM-MDS) of hematopathologists and hematologists expert in the field of myelodysplastic syndrome reviewed the morphological features of bone marrows from all subtypes of myelodysplastic syndrome and agreed on a set of recommendations, including recommendations for the definition and enumeration of blast cells and ring sideroblasts. It is recommended that (1) agranular or granular blast cells be defined (replacing the previous type I, II and III blasts), (2) dysplastic promyelocytes be distinguished from cytologically normal promyelocytes and from granular blast cells, (3) sufficient cells be counted to give a precise blast percentage, particularly at thresholds that are important for diagnosis or prognosis and (4) ring sideroblasts be defined as erythroblasts in which there are a minimum of 5 siderotic granules covering at least a third of the nuclear circumference. Clear definitions and a differential count of a sufficient number of cells is likely to improve precision in the diagnosis and classification of myelodysplastic syndrome. Recommendations should be applied in the context of the WHO classification.
Topics: Anemia, Sideroblastic; Decision Making; Europe; Granulocyte Precursor Cells; Humans; International Cooperation; Myelodysplastic Syndromes; United States; World Health Organization
PubMed: 18838480
DOI: 10.3324/haematol.13405 -
BMJ Case Reports Jan 2024Myeloid sarcoma is a very rare extramedullary malignant tumour, most often associated with acute myeloid leukaemia. We report the case of a man in his early 20s who...
Myeloid sarcoma is a very rare extramedullary malignant tumour, most often associated with acute myeloid leukaemia. We report the case of a man in his early 20s who presented with chronic headache, raised intracranial pressure and progressive vision loss of 2 years duration with no systemic manifestations. He had a history of myeloid sarcoma of the left thigh 15 years ago, treated with external beam radiotherapy and in complete remission for more than 13 years. However, the progressive blindness remained unexplained for 2 years, and he was eventually diagnosed with isolated meningeal relapse without marrow or systemic involvement. Imaging revealed subarachnoid haemorrhage, diffuse leptomeningeal enhancement and involvement of lower dorsal cord and conus, and cerebrospinal fluid cytology showed myeloid blasts. He was managed with intrathecal chemotherapy and craniospinal irradiation, after which he had mild improvement in vision.
Topics: Male; Humans; Sarcoma, Myeloid; Neoplasm Recurrence, Local; Meningeal Neoplasms; Blindness; Granulocyte Precursor Cells
PubMed: 38191225
DOI: 10.1136/bcr-2023-256821