Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023467 (acute myeloid leukemia)
 35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Therapy with DNA topoisomerase II inhibitors has been shown to result in an increased risk of acute myeloid leukemia (AML), often presenting balanced translocations to chromosome bands 11q23 and 21q22. Also other balanced aberrations, more rarely observed in therapy-related AML (t-AML), such as t(15;17) and inv(16) have been associated with these drugs. Recently we observed a case of chronic myeloid leukemia (CML) with t(9;22) after therapy of a germ cell tumor with etoposide, cisplatin and bleomycin. Based on this case and a review of chemotherapy-related leukemias with t(9;22) from the literature, we suggest a causal relationship between therapy with DNA topoisomerase II inhibitors and development of various types of leukemia carrying the Philadelphia chromosome.
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PMID:Chemotherapy-related - late occurring - Philadelphia chromosome in AML, ALL and CML. Similar events related to treatment with DNA topoisomerase II inhibitors? 930 14

Several antineoplastic agents used in the treatment of hematologic malignancies exert their cytotoxic effects by inhibiting the activity of nuclear DNA topoisomerase (topo) I or II. Mechanisms of drug resistance to topoisomerase inhibitors have been defined at the molecular level from in vitro studies using model cell lines, and include quantitative and qualitative changes in topo I and II. The possible roles of these mechanisms in clinical drug resistance and clinical outcomes for patients with hematologic malignancies are now under investigation. Available data indicate that the blast content of topo II does not correlate with clinical outcome in acute myeloid leukemia (AML), and this may also be true in acute lymphocytic leukemia (ALL). Chronic lymphocytic leukemia (CLL) cells are resistant to topo II inhibitors because they express low levels of topo II. Further studies using sequential biopsy samples and assays of topoisomerase activity should establish the role that changes in topo I and II activity play in the development of drug resistance in hematologic malignancies.
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PMID:Drug resistance to DNA topoisomerase I and II inhibitors in human leukemia, lymphoma, and multiple myeloma. 940 61

Although the presence of a chromosome 11q23 breakpoint is of recognized poor prognosis in acute lymphoblastic leukemia, its prognostic significance in acute myeloid leukemia (AML) has been the object of conflicting reports, perhaps reflecting the possibility of different entities. It has been found that only typical and generally balanced 11q23 chromosomal anomalies involve the MLL gene while atypical and generally unbalanced do not. To determine whether these two categories of AML patients had different initial characteristics and evolution, supporting different pathogenetic mechanisms, we analyzed clinical and biologic characteristics of newly diagnosed AML patients with balanced 11q23 breakpoint and/or MLL rearrangement seen over a 10-year period in our institution and compared them to cases with unbalanced 11q23 anomaly seen over the same period. These two categories of patients were compared with newly diagnosed patients with normal karyotype and no MLL rearrangement when tested, seen over the same period of time and treated similarly. Over this period, 442 newly diagnosed adult (> 15 years) AML seen in our institution had a successful karyotype performed before any therapy. Thirty-six cases (8%) had a chromosome 11q23 breakpoint including 19 cases with a balanced translocation or inversion and 17 cases with an unbalanced anomaly. Eighty-seven recently diagnosed cases of AML, for whom frozen cellular material was available, were analyzed by Southern blot for the presence of MLL gene rearrangement. Fourteen cases (16% of the tested cases) had a rearrangement of the MLL gene, including seven cases with an apparently successful karyotype not showing any 11q23 breakpoint and two cases with no available karyotype. The only case with unbalanced 11q23 chromosomal anomaly which was tested had no MLL rearrangement. There was a clear-cut clinical difference between the 28 patients having a balanced 11q23 anomaly/MLL rearrangement and the 17 patients having an unbalanced chromosomal anomaly: AML with unbalanced 11q23 anomalies occurred in older patients (P = 0.07) tended to be less frequently associated with previous exposure to topoisomerase II-active drugs and with M4/M5 FAB cytological subtypes, were always associated with other chromosomal anomalies (P < 0.0001), expressed more frequently the CD34 antigen (P = 0.05) and were of considerably poorer prognosis for achievement of CR (P = 0.005) and survival (P = 0.0005). When compared to the control population, patients with balanced anomalies had more frequent history of toxic exposure (P = 0.0003) particularly to topoisomerase II-active drugs, tended to be more frequently of M4/M5 FAB subtypes (P = 0.07), expressed more frequently HLA-DR antigen (P = 0.02) and had shorter DFS (P = 0.02). Patients with unbalanced anomalies had more frequent splenomegaly (P = 0.009), lower WBC count (P = 0.04), and much poorer prognosis for CR achievement (P = 0.0001), survival (P < 0.0001) and DFS (P = 0.01). This study confirms the high frequency of 11q23 chromosomal breakpoint/MLL rearrangement in adult AML and the probable existence of two different entities with different clinical features according to the presence of a balanced or unbalanced cytogenetic abnormality, the latter being not associated with MLL rearrangement.
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PMID:Clinical and biological characteristics of adult de novo and secondary acute myeloid leukemia with balanced 11q23 chromosomal anomaly or MLL gene rearrangement compared to cases with unbalanced 11q23 anomaly: confirmation of the existence of different entities with 11q23 breakpoint. 943 17

Three DNA damage-responsive cell cycle checkpoints can be shown to operate in diploid human fibroblasts. One checkpoint arrests growth in G1, another inhibits replicon initiation in S phase cells, and the third delays progression from G2 into mitosis. Progression from G2 into M is controlled in part by a cyclin-dependent kinase (cyclin B/Cdk1) that is regulated by tyrosine phosphorylation. Phosphorylation of Tyr15 on Cdk1 is inhibitory for kinase activity. Activation of cyclin B/Cdk1 at the onset of mitosis is accomplished by a phosphatase, Cdc25C, that interacts with cyclin B/Cdk1 in an autocatalytic feedback loop to remove the inhibitory phosphate at Tyr15 and activate kinase activity. DNA damage triggers G2 delay by inhibiting formation of the autocatalytic feedback loop so that dephosphorylation of Tyr15 does not occur. This suppression of activation of cyclin B/Cdk1 appears to account for the failure of damaged G2 cells to progress into mitosis. Once the damage to DNA is repaired, cells resume progression into mitosis as the cycle is re-engaged. The isoflavone genistein inhibits tyrosine kinases, including one that phosphorylates Cdk1 on Tyr15. This kinase, p56/p53lyn is rapidly induced by treatments that trigger cell cycle checkpoints (ionizing radiation, cytosine arabinoside), suggesting that this kinase may actively delay the onset of mitosis by phosphorylating Tyr15 on Cdk1. Genistein also inhibits type II DNA topoisomerase to produce a form of DNA damage that triggers all of the DNA damage-responsive cell cycle checkpoints. A brief 10 min incubation with the topoisomerase poison amsacrine was sufficient to trigger the S phase checkpoint response and inhibit replicon initiation. Inhibition of replicon initiation by 1 microM amsacrine was maximal 20-30 min after drug treatment and by 120 min, the checkpoint response had decayed to allow near control rates of replicon initiation. Topoisomerase II poisons also are powerful clastogens inducing lethal and carcinogenic chromosomal aberrations. Type II topoisomerase can break DNA in a region of chromosome 11q23 that contains the ataxia telangiectasia gene (ATM). The ATM gene controls all of the DNA damage-responsive cell cycle checkpoints. Chromosomal aberrations in 11q23 are frequently seen in acute myeloid leukemia that develops as a consequence of etoposide chemotherapy. Thus, topoisomerase poisons such as genistein may trigger chromatid breakage to inactivate AT gene function, disable cell cycle control, and induce genetic instability.
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PMID:Human topoisomerase II function, tyrosine phosphorylation and cell cycle checkpoints. 949 43

In order to better understand acquired resistance to antitumor agents in acute myelogenous leukemia (AML), we investigated various drug resistance mechanisms; namely, topoisomerase II (topo II), glutathione system and P-glycoprotein (P-gp). Blast cells of 31 patients with AML, 21 before treatment (BT) and 10 at relapse (AR) were studied. Topo II was evaluated by Western blot analysis. Glutathione-S-transferase activity (GST) and glutathione content (GSH) were investigated by spectrophotometric assays. GST isoenzymes (-alpha, -mu and -pi) were tested by Western blot and by immunocytochemical staining. P-gp was evaluated by an immunocytochemical method using MRK 16 antibody. Our results showed that GST, GSH and GST-pi were similar in patients BT and AR GST-mu was detected in 13/21 AML BT and in 5/10 AML AR. GST-alpha expression was higher (p < 0.05) in AML AR (60 +/- 105 AU/mg) compared to AML BT (10 +/- 10 AU/mg). A relationship was found between GST-pi quantitation evaluated by Western blot and immunocytochemical staining, whereas no correlation was observed for the other isoenzymes. Topo II was detected in only 4 AML BT and 3 AML AR. Eleven out of 21 AML BT and 3/10 AML AR expressed P-gp with immunohistochemical study. These results indicate that only the "glutathione system", especially the GST-alpha could be involved in drug resistance in AML.
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PMID:Glutathione system, topoisomerase II level and multidrug resistance phenotype in acute myelogenous leukemia before treatment and at relapse. 949 83

Myelodysplastic syndromes (MDS) are a heterogeneous and common group of clonal hematological disorders characterized by cytopenias, dysplastic changes of hematopoietic cells, and a high rate of transformation into acute myeloblastic leukemia (AML). MDS provide a clinical model for studying the emergency and progression of malignancy. The initiating events leading to MDS remain almost unknown. Imbalance of proliferative and differentiating capabilities of progenitor hematopoietic cells along with abnormalities in the normal process of apoptosis are involved in both the pathogenesis of MDS and transformation into AML. Multiple genomic lesions, comprising oncogene activation and tumor-suppressor gene inactivation, are probably required. Alkylating agents, cytotoxic drugs targeting topoisomerase II and benzene are the only clear etiological factors identified. Advanced age and great prognostic variability, not explained by the FAB subtype, complicates the design and analysis of clinical trials and therapy-planning. The use of recently developed prognostic scores for selecting the best treatment according to the expected risk is encouraged. In most patients therapy is unsatisfactory. At present, bone marrow transplantation is considered as the only curative approach. A better knowledge of the pathobiology of MDS should be valuable to develop new, more rationale and effective therapies.
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PMID:Etiopathogeny, prognosis and therapy of myelodysplastic syndromes. 949 87

Translocations of the MLL gene at chromosome band 11q23 are the most common cytogenetic alterations in de novo leukemia in infants and in leukemia related to chemotherapy with DNA topoisomerase II inhibitors. Experiments on knock-in mice suggest that additional mutational events may by required for full leukemogenesis. Therefore, we used single-strand conformation polymorphism analysis and an allele-specific restriction enzyme assay to investigate the frequency of KRAS and NRAS mutations in 32 pediatric leukemias with translocation of the MLL gene. Of 25 de novo cases, 13 were acute lymphoblastic leukemia (ALL), 10 were acute myeloid leukemia (AML), and 2 were biphenotypic. Three secondary leukemias were AML, 1 was biphenotypic, 1 was ALL, and 2 were diagnosed as myelodysplasia. The frequency of RAS mutations was 2 of 10 in de novo AML. Both mutations occurred in infant monoblastic variants. RAS mutations were otherwise absent in this series. This is the first report of congenital leukemias where translocation of the MLL gene and RAS mutation coexist. The frequency of RAS mutations in de novo AMLs with MLL gene translocations is similar to that in other forms of AML, but RAS mutations play a limited role in lymphoid and treatment-related leukemias with similar translocations.
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PMID:RAS mutations in pediatric leukemias with MLL gene rearrangements. 952 5

Therapy-related acute myeloid leukemias with balanced translocations affecting the 11q23 chromosome region are one of the most serious complications of treatments with topoisomerase II inhibitor drugs as epipodophillotoxins and anthracyclines. 1,2-5 These cases are usually associated with short interval time from previous chemotherapies, absence of myeloid dysplastic phase, hyperleukocytosis and young age. We and others have recently identified and cloned the ALL1 gene at 11q23 band (also named MLL, HRX. Hrxt) which is consistently altered in t-AML following therapies with topo II targeting drugs. However, there are few reports of cases of t-AML, clinically and biologically similar to the subtype of leukemias secondary to exposure to topo II inhibitors drugs but without the involvement of the ALL1 gene. These observations suggest that genes other than ALL1 which are etiopathogenetically relevant for hematological neoplasias are located in this cytogenetic region.
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PMID:Therapy-related acute leukemia associated with involvement of 11q23 after high grade non-Hodgkin lymphoma. 957 84

Segmental jumping translocations are chromosomal abnormalities in treatment-related leukemias characterized by multiple copies of the ABL and/or MLL oncogenes dispersed throughout the genome and extrachromosomally. Because gene amplification potential accompanies loss of wild-type p53, we examined the p53 gene in a case of treatment-related acute myeloid leukemia (t-AML) with MLL segmental jumping translocation. The child was diagnosed with ganglioneuroma and embryonal rhabdomyosarcoma (ERMS) at 2 years of age. Therapy for ERMS included alkylating agents, DNA topoisomerase I and DNA topoisomerase II inhibitors, and local radiation. t-AML was diagnosed at 4 years of age. The complex karyotype of the t-AML showed structural and numerical abnormalities. Fluorescence in situ hybridization analysis showed multiple copies of the MLL gene, consistent with segmental jumping translocation. A genomic region including CD3, MLL, and a segment of band 11q24 was unrearranged and amplified by Southern blot analysis. There was no family history of a cancer predisposing syndrome, but single-strand conformation polymorphism (SSCP) analysis detected identical band shifts in the leukemia, ganglioneuroma, ERMS, and normal tissues, consistent with a germline p53 mutation, and there was loss of heterozygosity in the ERMS and the t-AML. Sequencing showed a CGA-->TGA nonsense mutation at codon 306 in exon 8. The results of this analysis indicate that loss of wild-type p53 may be associated with genomic instability after DNA-damaging chemotherapy and radiation, manifest as a complex karyotype and gene amplification in some cases of t-AML.
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PMID:Association of germline p53 mutation with MLL segmental jumping translocation in treatment-related leukemia. 961 38

A 59-year-old female suffering from malignant lymphoma developed therapy-related acute myeloblastic leukemia (t-AML) after chemotherapy consisting of treatment with DNA-topoisomerase II inhibitors, etoposide and mitoxantrone, and an alkylating agent, cyclophosphamide. The cumulative dose of etoposide administration was 5500 mg; 1500 mg given intravenously and 4000 mg orally. One year later, she suddenly developed AML of FAB M2. Cytogenetic analysis of bone marrow cells revealed deletion of 7q and a rare translocation, t(16;21)(q24;q22). Southern blot analysis of bone marrow cells did not detect rearrangement of the AML1 gene, however, fluorescence in situ hybridization (FISH) analysis of bone marrow cells at interphase and metaphase revealed a translocational splitting between chromosome 21 involving AML1 gene and chromosome 16. These results suggest that the breakpoint is not located in the breakpoint cluster region for t(8;21). The patient was treated with chemotherapy and entered complete remission.
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PMID:A case of therapy-related acute myeloblastic leukemia with t(16;21)(q24;q22) after chemotherapy with DNA-topoisomerase II inhibitors, etoposide and mitoxantrone, and the alkylating agent, cyclophosphamide. 963 85


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