Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In approximately 20% of cases of severe congenital neutropenia (SCN), mutations are found in the gene encoding the granulocyte colony-stimulating factor receptor (G-CSF-R). These mutations introduce premature stop codons, which result in truncation of 82-98 COOH-terminal amino acids of the receptor. SCN patients who develop secondary myelodysplastic syndrome and acute myeloid leukemia almost invariably acquired a GCSFR mutation, suggesting that this genetic alteration represents a key step in leukemogenesis. Here we show that an equivalent mutation targeted in mice (gcsfr-Delta715) results in the selective expansion of the G-CSF- responsive progenitor (G-CFC) compartment in the bone marrow. In addition, in vivo treatment of gcsfr-Delta715 mice with G-CSF results in increased production of neutrophils leading to a sustained neutrophilia. This hyperproliferative response to G-CSF is accompanied by prolonged activation of signal transducer and activator of transcription (STAT) complexes and extended cell surface expression of mutant receptors due to defective internalization. In view of the continuous G-CSF treatment of SCN patients, these data provide insight into why progenitor cells expressing truncated receptors clonally expand in vivo, and why these cells may be targets for additional genetic events leading to leukemia.
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PMID:Sustained receptor activation and hyperproliferation in response to granulocyte colony-stimulating factor (G-CSF) in mice with a severe congenital neutropenia/acute myeloid leukemia-derived mutation in the G-CSF receptor gene. 998 83

We evaluated the effect of SCF on myeloid differentiation by correlating clonogenic potential (as CFU-GM), bone marrow (BM) plasma SCF levels and CD34/c-kit expression in 57 MDS samples. There was a significant correlation between low SCF levels and 'leukemic' in vitro growth, the number of clusters and the colony/cluster ratio. No correlation was found between BM plasma SCF levels, the pattern of growth and CD34+ c-kit+ expression. These data seem to exclude any direct effect of SCF on leukemogenesis, but suggest that low plasma SCF levels may be at least partially responsible for leukemic growth in MDS.
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PMID:Low plasma stem cell factor levels correlate with in vitro leukemic growth in myelodysplastic syndromes. 1007 Oct 80

Therapy-related acute myeloid leukemia and myelodysplastic syndrome (t-AML and MDS) are severe late complications of treatment with genotoxic chemotherapeutic agents. Children with neurofibromatosis type 1 (NF1) are predisposed to malignant myeloid disorders that are associated with inactivation of the NF1 tumor suppressor gene in the leukemic clone. Recent clinical data suggest that NF1 might be also associated with an increased risk of t-AML after treatment with alkyating agents. To test this hypothesis, we administered cyclophosphamide or etoposide to cohorts of wild-type and heterozygous Nf1 knockout mice. Cyclophosphamide exposure cooperated strongly with heterozygous inactivation of Nf1 in myeloid leukemogenesis, while etoposide did not. Somatic loss of the normal Nf1 allele correlated with clinical disease and was more common in 129/Sv mice than in 129/Sv x C57BL/6 animals. Leukemic cells showing loss of heterozygosity at Nf1 retained a structural allele on each chromosome 11 homolog. These studies establish a novel in vivo model of alkylator-induced myeloid malignancy that will facilitate mechanistic and translational studies.
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PMID:Myeloid malignancies induced by alkylating agents in Nf1 mice. 1033 66

The objectives of this review are to: (a) demonstrate that the male CBA/Ca mouse has several characteristics that make it an excellent animal for the study of leukemogenesis, (b) show that several of the genetic abnormalities observed in the male CBA/Ca mouse during the development of radiation induced acute myeloid leukemia (AML) are syntenic with those frequently detected in patients with myeloid disorders such as myelodysplastic syndrome and AML, (c) illustrate that leukemia-related chromosomal lesions are the indicators for high risk individuals.
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PMID:Advantages of the CBA mouse in leukemogenesis research. 1034 12

Dose escalation during consolidation therapy of de novo AML, including myeloablative chemotherapy supported with autologous peripheral blood stem cell transplantation (aPBSCT), continuously improved outcome. Therefore, quality control of transplants is getting increasing interest. We studied leukapheresis products (LPs), consecutively collected during postremission treatment of 20 patients with de novo AML for minimal residual disease (MRD) by 5-parametric flow cytometry and for myelodysplasia (MDS)-associated alterations by paired lineage-selected colony assays for colony-forming units-megakaryocytes (CFU-mega) and burst-granulocytes-monocytes colony-forming units (CFU) to evaluate the predictive value of these transplant-associated parameters on outcome. We defined the leukemia-associated immunophenotype at diagnosis and studied the impact of MRD detection in LPs collected after double induction with TAD (thioguanine, daunorubicin, cytarabine) and HAM (mitoxantrone, high-dose cytarabine, n=18 patients) and TAD consolidation treatment (n=20 patients) on outcome after aPBSCT. The level of MRD in the transplants correlated with the relapse-free survival (RFS) using a cut-off level of 1 x 10(-3) residual leukemic cells. The median RFS was 6 months for the group with > or = 1 x 10(-3) residual leukemic cells and has not been reached in the group with low MRD levels (< 1 x 10(-3)). By using the same cut-off level a weak correlation could also be demonstrated between MRD in the pregraft bone marrow and RFS (P = 0.04). Quantitatively abnormal megakaryocytic colony growth in the back-up LPs collected after double induction and in the transplant LPs was characterized by the ratio CFU-mega/CFU. In the group of relapsing patients the ratio CFU-mega/CFU was significantly lower than in the group of patients with CCR (P = 0.004), both in the back-ups and in the transplants. All patients with CFU-mega/CFU ratios < 0.12 relapsed, five of seven patients developed MDS before progressing to full leukemic relapse. Using the optimized cut-off level for the ratio CFU-mega/CFU (< vs > or = 0.12), seven of 10 relapsing patients (70%) could be identified to be at risk of relapse, whereas MRD in the transplants identified only 50% of the relapses and MRD in the pregraft bone marrow 25%. In conclusion, the study could identify two pretransplant risk factors predicting relapse in patients with AML receiving aPBSCT in first CR: MRD in transplants as well as MDS-like alterations within the transplants. These results may have multifold implications on the design of risk-adapted chemotherapy as well as on purging techniques and may contribute to a better understanding of leukemogenesis.
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PMID:Transplant characteristics: minimal residual disease and impaired megakaryocytic colony growth as sensitive parameters for predicting relapse in acute myeloid leukemia. 1045 Jul 51

This study, using the CBA/Ca mouse as a model, compares genetic lesions associated with radiation- and benzene-induced acute leukemias. Specific types of leukemia included in the analyses are radiation-induced acute myeloid leukemia (ML), and benzene-induced lymphoblastic leukemias, lymphomas, or mix-lineage leukemias. These leukemias have histopathological characteristics similar to those seen in human acute leukemias. G-band cytogenetic analysis showed that specific deletions involving regions D-E of one copy of mouse chromosome 2 [del(2)(D-E)] were frequently associated in both radiation- and benzene-induced acute leukemias. In addition, translocations of chr2(D-E) were also observed in some cases. These results suggest an important role of chr2 (D-E) deletions and translocations in the development of radiation- and benzene-induced murine acute leukemias. Fluorescence in situ hybridization with DNA probes specific for 2(D-E), constructed in our laboratory by means of chromosomal microdissection and PCR amplification, also demonstrate 2(D-E) deletions and/or translocations in these leukemic cells. Aneuploidy of chromosomes 3, 15, 16, and Y were also frequently detected in benzene-induced leukemic cells with or without lesions on chr2. These cytogenetic findings support the previous observations that metabolites of benzene lead to spindle-fiber disruption or abnormal cytokinesis in exposed animals. In summary, genetic instabilities observed in leukemic cells isolated from mice that had developed leukemia after exposure to radiation or benzene are syntenic with those frequently detected in patients with myelodysplastic syndrome, acute ML, and acute lymphoblastic leukemia. Thus, the CBA/Ca mouse has several characteristics that make it an excellent model for the study of radiation or benzene leukemogenesis in humans.
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PMID:Characterization of genetic instability in radiation- and benzene-induced murine acute leukemia. 1051 76

Traditionally, acute myeloid leukemia (AML) has been diagnosed and classified based on the morphologic and cytochemical criteria of the French-American-British (FAB) classification system. However, more recent studies have demonstrated that the cytogenetic and molecular genetic abnormalities consistently associated with distinct forms of AML confer the most important prognostic information. Each broad category of de novo AML that arises in infants and children, young adults, and the elderly, or, AML arising secondary to antecedent myelodysplasia (MDS) or prior exposure to chemotherapy, radiotherapy, or environmental agents is characterized by distinct cytogenetic and molecular genetic abnormalities. Over the past 15 years, a number of these recurrent cytogenetic abnormalities have been cloned and characterized, yielding valuable insights into the mechanisms of leukemogenesis and providing powerful molecular tools for precise diagnosis and monitoring of minimal residual disease. As cytogenetic and molecular genetic characterization of AML cells is now considered crucial for both diagnostic and therapeutic decision-making, it is essential to have a working knowledge of the molecular basis of AML. This chapter reviews the molecular genetic features of different forms of AML and the new automated molecular technologies for residual disease assessment; the emerging molecular paradigms in this disease that are being exploited for therapeutic decision-making are presented.
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PMID:Molecular evaluation of acute myeloid leukemias. 1053 Jul 20

We describe a 41-year-old man with CD7-positive acute myeloid leukemia (AML-M0) with trilineage-myelodysplasia. Chromosome analysis of the bone marrow cells showed 46.XY.t(2;4;12) (p21;q12;p13). Cytological and clinical features of our case were quite similar to those of AML with t(4;12)(q11-12;p13). The karyotypic interpretation was confirmed by fluorescence in situ hybridization (FISH) by using the whole-chromosome painting probes specific for chromosomes 2, 4, and 12. FISH analysis with the use of the YAC 936e2 probe, which covers the TEL gene, did not show the split signal, suggesting that a gene other than TEL was involved in the leukemogenesis of the present case. Our case with AML with t(2;4;12)(p21;q12;p13) appears to be the first case of a variant type of AML with t(4;12) (q11-12;p13).
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PMID:A new translocation, t(2;4;12)(p21;q12;p13), in CD7-positive acute myeloid leukemia: a variant form of t(4;12). 1054 63

We report five cases of myeloid disorders in which trisomy 21 (+21) was found as the sole acquired karyotypic abnormality, comprising two cases of acute myeloid leukemia (AML) and three cases of myelodysplastic syndrome (MDS). In this series, MDS patients with +21 presented as high grade disease, which included two cases of refractory anemia with excess of blasts (RAEB) and one case of refractory anemia with excess of blasts in transformation (RAEBt), and showed rapid disease progression. Significant thrombocytopenia was observed in all three patients, and bone marrow examination showed a marked reduction in megakaryocytes. AML patients with +21 included one case each of AML-M2 and M4. Despite the poor prognosis reported in AML patients with +21 as the sole abnormality, the patient in our series who was able to complete intensive treatment was cured of disease. The role of +21 in leukemogenesis is reviewed.
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PMID:Trisomy 21 as the sole acquired karyotypic abnormality in acute myeloid leukemia and myelodysplastic syndrome. 1057 14

The frequency of leukemia and myelodysplasia following treatment with cytotoxic agents is increasing. Theses treatment-related leukemias raise both theoretical and practical concerns. On a theoretical basis, cytogenetic and molecular abnormalities described constitute useful models to study leukemogenesis. On a practical basis, prognosis of treatment related-leukemia is somehow unfavorable and implies to take in account this risk in the development of combination therapy for solid tumors or hematological malignancies. There are two distinctive types of treatment-induced leukemia: those secondary after alkylating agents and those secondary after topoisomerase-II- inhibitors. These two types of leukemia after regarding their clinical and their hematological characteristics, but also regarding their prognosis and their associated molecular abnormalities. Leukemias induced by alkylating agents occur generally 5 or 6 years after the beginning of the chemotherapy and are preceded by a more or less long phase of pancytopenia or myelodysplasia and according to their cytologic aspects are difficult to be classified within FAB classification. Their prognosis is pejorative. The most commonly found cytogenetic abnormalities associated with these types of induced leukemia are losses or deletions of chromosomes 5 and 7. Leukemias induced by topoisomerase-II-inhibitors occur shortly after the treatment (12 to 30 months), they begin generally suddenly without preleukemia prodom and their more frequent cytological aspects are M4 and M5 type. The prognosis is less severe than alkylating agent related forms with higher response rates and is dependant of discovered cytogenetic abnormalities. The more frequent molecular abnormalities are not chromosome deletions but balanced translocations. They affect particularly the MLL gene located at band 11q23. Other translocations have been described in this type of leukemia and are comparable to the one found in the de novo leukemia (t8;21, t15;17) for example. The evaluation of the risk of treatment-related leukemia for a given chemotherapeutic agent is difficult as for as current treatment use the combination of several agents potentially leukemogenic (chemotherapy and radiotherapy, combination chemotherapy). It is necessary to set up an up-dated data register in order to centralize all therapy-related myelodysplasia and leukemia within the treatment of a given type of cancer.
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PMID:[Leukemias induced by anticancer chemotherapies]. 1058 9


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