Academic literature on the topic 'Leukemia, Erythroblastic, Acute'

Myasthenia Gravis is a chronic autoimmune neuromuscular disorder that is characterized by fluctuating weakness of the voluntary muscle groups. It occurs in all races, at any age (especially under 40 or over 60), both genders, with a prevalence of 20/100,000 population in the United States. About 15 percent of patients with myasthenia gravis have thymomas, much rarely another solid tumor, thyroid dysfunction and more often another autoimmune condition, such as rheumatoid arthritis, lupus, Biermer anaemia. We present a 72 year-old male patient with ocular myasthenia gravis treated with cholinesterase inhibitors, that, after many laboratory exams, was diagnosed with acute erythroblastic leukemia, a very rare clinical association.

Abstract Acute erythroid leukemia (AEL) is a subtype of Acute Myeloid Leukemia (AML), comprising less than 5% of AML cases, characterized by erythroblastic proliferation. It’s a rare and aggressive form of acute leukemia whose biology remains poorly described, and there are many controversies around diagnosis influencing prognostic and therapeutic challenges. The average survival time for this type of Leukemia is 3 months. We present a unique case of a patient already known to have Chronic Kidney Disease stage G4, diagnosed with Acute Erythroid Leukemia (Fab M6), confirmed by Flow-Cytometry (infiltration of 93% erythroblasts in the Bone Marrow), who underwent specific chemotherapy (Azacitidine and Venetoclax) for 4 months. Due to severe pancytopenia and the presence of leukemic hiatus, it was challenging to avoid hemodialysis/hemofiltration, overcome metabolic acidosis and hyperuricemia, preserve serum creatinine levels at acceptable levels, and maintain hydroelectrolytic balance. All drug dosages (chemotherapy and supportive treatment) were adapted to the patient’s renal function.

Pure erythroid leukemia (PEL) is an extremely rare type of acute myeloid leukemia (AML), accounting for fewer than 1% of all AML cases. A 16-year-old girl, without any medical history, presented fever, severe fatigue and mucocutaneous bleeding. Her peripheral blood smears showed myeloid blasts with deep basophilic cytoplasm and circulating erythroblasts. Her bone marrow aspiration showed a very rich marrow with 93% erythroblastic hyperplasia with 30% excess of proerythroblasts, and 4% of myeloblasts. PEL appeared to be the definitive diagnosis after evaluating the immunophenotypic findings. Her general condition deteriorated during medical diagnosis, and she died soon after starting chemotherapy.

Abstract Bsp-1 is an IgM murine monoclonal antibody raised against the human erythroblastic leukemia cell line (HEL) that reacts with basophils but not neutrophils or eosinophils. Western blotting techniques showed that Bsp-1 reacts with a 45-kilodalton surface antigen on HEL cells. The distribution of Bsp-1 antigen on leukemic cells is confined to a basophilic leukemia cell line, KU812, chronic myeloid leukemia with basophilia, and some cases of acute undifferentiated leukemia. Bsp-1 might therefore be a useful reagent for the study of basophil function and differentiation.

Bsp-1 is an IgM murine monoclonal antibody raised against the human erythroblastic leukemia cell line (HEL) that reacts with basophils but not neutrophils or eosinophils. Western blotting techniques showed that Bsp-1 reacts with a 45-kilodalton surface antigen on HEL cells. The distribution of Bsp-1 antigen on leukemic cells is confined to a basophilic leukemia cell line, KU812, chronic myeloid leukemia with basophilia, and some cases of acute undifferentiated leukemia. Bsp-1 might therefore be a useful reagent for the study of basophil function and differentiation.

Abstract The leukemia stem cell model suggests that elucidation of the genes that regulate growth ability within the leukemia cell hierarchy will have important clinical relevance. We showed that the expression of NR2F6 (EAR-2), is greater in clonogenic leukemia single cells than in leukemia cells that do not divide, and that this gene is over-expressed in patients with acute myeloid leukemia and myelodysplastic syndrome. In vivo, overexpression of EAR-2 using a retroviral vector in a chimeric mouse model leads to a condition that resembles myelodysplastic syndrome with hypercellular bone marrow, increased blasts, abnormal localization of immature progenitors, morphological dysplasia of the erythroid lineage and a competitive advantage over wild-type cells, that eventually leads to AML in a subset of the mice, or after secondary-transplantation. Interestingly, animals transplanted with bone marrow that over-expresses EAR-2 develop leukemia that is preceded by expansion of the stem cell compartment in the transplanted mice—suggesting that EAR-2 is an important regulator of hematopoietic stem cell differentiation. Here we report that over-expression of EAR-2 also has a profound effect on the differentiation of erythroid progenitor cells both in vitro and in vivo. Studies of the roles of EAR-2 in normal primary bone marrow cells in vitro showed that overexpression of EAR-2 profoundly impaired differentiation along the erythroid lineage. EAR-2 over-expressing bone marrow cells formed 40% fewer BFU-E colonies, but had greatly extended replating capacity in colony assays. While knockdown of EAR-2 increased the number of cells produced per BFU-E colony 300%. Normal mice transplanted with grafts of purified bone marrow cells that over-expressed EAR-2 developed a rapidly fatal leukemia characterized by pancytopenia, enlargement of the spleen, and infiltration of blasts into the spleen, liver and peripheral blood. Sick animals had profound reduction of peripheral blood cell counts, particularly anemia with a 55% reduction in hemoglobin levels. Anemia was evident even on gross inspection of the blood and the liver in EAR-2 overexpressing animals. Analysis of the leukemic cells revealed an erythroblastic morphology, with the immunophenotype lineageneg, CD71high, TER119med. Hence, we wondered weather EAR-2 caused leukemia by arresting erythroid progenitor cell differentiation. Examination of the bone marrow of pre-leukemic animals showed a four-fold increase in cells with a pro-erythroblastic immunophenotype (CD71highTER119med , region I), and a four-fold decrease in orthochromatophilic erythroblasts (CD71lowTER119high , region IV). We observed no change in the numbers of basophilic erythroblasts (CD71highTER119high , region II) or late basophilic and polychromatophilic erythroblasts (CD71medTER119high, region III). These data suggests that over-expression of EAR-2 blocks erythroid cell differentiation at the pro-erythroblastic stage. Since EAR-2 over-expressing recipients died within 4 week, we wanted to definitively test whether animals had compromised radioprotection. We showed that decreasing the size of the bone marrow graft, reduced survival of the EAR-2 over-expressing cohort by a week, but had no effect on control animals proving that EAR-2 over-expression has a profound effect on erythropoietic reconstitution in vivo. Mechanistically, we show that DNA binding is necessary for EAR-2 function, and that EAR-2 functions in an HDAC-dependent manner, regulating expression of several genes. Pre-leukemic pro-erythroblastic cells (CD71highTER119med) that over-expressed EAR-2 had lower expression of genes involved in erythroid differentiation such as GATA1, EBF1, inhibitor of NFKB (NFKBia), ETV6, CEBP/a, LMO2, and Nfe2, and increased expression of GATA2, GLI1, ID1 and PU.1 than GFP control pro-erythroblasts. These data establish that EAR-2 is a novel oncogene whose cellular function is to regulate terminal differentiation of erythroid cells at the proerythroblastic (CD71highTER119med) stage by deregulating gene expression necessary for erythroid differentiation. Disclosures Ichim: Entest BioMedical: Employment, Equity Ownership, Patents & Royalties, Research Funding. Koos:Entest BioMedical: Employment, Equity Ownership, Patents & Royalties, Research Funding.

Apart from CAD, the transient liberation of AIF during day 6 of TF-1 differentiation could pose another threat to the genomic DNA in cells. We have demonstrated the absence of AIF in the nucleus of TF-1 cells despite its release from the mitochondria by using confocal studies. Moreover, the expression of heat shock protein 70 kDa (Hsp70), a well-known antagonist of AIF, was found to be temporarily increased at day 6. Taken together, our results implied a plausible retention of AIF in the cytoplasm by Hsp70. Although Hsp70 is commonly utilized by many cancer cells to counteract AIF and avoid DNA fragmentation, we are the first to demonstrate its role in suppressing AIF during normal erythroid maturation.
As a whole, we have illustrated that the activated caspase-3, mediated most likely by the mitochondrial pathway, is an essential component in the differentiation of TF-1 cells. Its activation was nevertheless not coupled with DNA fragmentation due to some protective mechanisms such as CAD downregulation, Hsp70 upregulation and overexpression of Bcl-XL. Our study therefore provides some insights in the understanding of the relationship between human erythropoiesis and apoptosis and a better understanding in this regard will undoubtedly facilitate the development of new drugs in the treatment of different hematopoietic diseases.
Caspases play a central role in apoptosis. Their activations during the process are accounted for different biochemical and morphological changes in apoptotic cells. Yet in recent years, increasing studies had shown that caspases were also involved in some non-apoptotic cellular events, including T and B-lymphocytes activation, as well as the terminal differentiation of lens cells, megakaryocytes and erythrocytes.
In order to find out other unknown cellular mechanisms in erythropoiesis, mRNA differential display was employed to compare the gene expression pattern of TF-1 cells at different stages of differentiation. Several differentially expressed genes were identified and subsequently confirmed by RT PCR. These genes include formin binding protein 3, destrin and T-complex protein-1 (TCP-1). Their involvement in erythroid differentiation was still not clear at the moment but would be investigated in the near future. Furthermore, aiming at identifying the interacting proteins or inhibitors of caspase-3 in the system, a pull down assay was developed by means of the bacterial expression of a recombinant human caspase-3 mutant protein. With the mutation in the active site, the binding of our recombinant caspase-3 mutant with two known partners ICAD and BIRII (Baculovirus Inhibitor of apoptosis protein Repeat II) domain has been demonstrated. We hope in the near future that it can be employed to fish out some novel caspase-3 substrates from the differentiating TF-1 cell lysate.
In the present study, the participation of caspase in in vitro erythropoiesis was investigated using a human erythroleukemia cell line TF-1. Erythropoietin (EPO) induced erythroid maturation of TF-1 as indicated by the expression of erythroid-lineage markers like glycophorin A (GPA), transferrin receptors (CD71) and synthesis of hemoglobin (Hb). Activation of caspase-3 was observed from day 6 to day 12 during TF-1 differentiation after EPO treatment. With the administration of caspase-3 specific inhibitor, expressions of GPA and CD71 were partially blocked, suggesting that caspase-3 activation is essential in erythropoiesis in our TF-1 model.
Possible involvement of the intrinsic and extrinsic apoptotic pathways was studied by investigating respectively the activation of pro-caspase-9 and -8. It was found that caspase-9, but not -8, was activated at the corresponding time point when caspase-3 was activated. Besides, a transient mitochondrial depolarization coupled with the release of cytochrome c and apoptosis inducing factor (AIF) were detected on day 6, strongly implying a role of mitochondria in triggering the activation of executioner caspase-3. On the other hand, GPA and CD71 expressions were blocked by the application of mitochondrial depolarization inhibitor cyclosporin A (CyA). Also, the recovery of mitochondrial membrane potential was found to be correlated with an overexpression of Bcl-XL at a late stage of TF-1 differentiation, and the role of Bcl-XL was subsequently manifested further by a significant retardation of erythroid differentiation in the siRNA Bcl-XL knocked down TF-1 cells.
The exact role of caspase-3 in erythroid differentiation is far from clear at this moment. Yet, its regulation in the process is equally intriguing. On the course of TF-1 maturation, activated caspase-3 was able to cleave and de-localize the Inhibitor of Caspase-activated DNase (ICAD) from the nucleus, but at the same time DNA fragmentation was not detected by TUNEL assay nor agarose electrophoresis. Furthermore, protection against DNA fragmentation was observed in the EPO-treated TF-1 cells when challenged with a potent apoptotic inducer staurosporine (STS). These observations are in contrast to our understanding that DNA is fragmented by CAD (Caspase-activated DNase) when ICAD in the ICAD-CAD complex is cleaved by caspase-3. For these apparently contradictory observations, we demonstrated that downregulation of CAD occurred at the mRNA and protein levels during the erythroid differentiation in TF-1. This provides a cell rescuing mechanism in non-apoptotic cells with activated caspases.
Lui Chun Kin Julian.
"September 2006."
Adviser: Siu Kai Kong.
Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1620.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (p. 239-253).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.