Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Determining in vitro drug resistance may reveal clinically relevant information in childhood leukemia. Using the methyl-thiazol-tetrazolium assay, the resistance of untreated leukemic cells to 21 drugs was compared in 128 children with acute myeloid leukemia (AML) and 536 children with acute lymphoblastic leukemia (ALL). The differences between 3 French-American-British (FAB) types (M1/M2, M4, and M5) were also compared. AML was significantly more resistant than ALL to the following drugs, as noted by the median resistance: glucocorticoids (greater than 85-fold), vincristine (4.4-fold), L-asparaginase (6.9-fold), anthracyclines (1.8- to 3.4-fold), mitoxantrone (2.6-fold), etoposide (4.9-fold), platinum analogues (2.4- to 3.4-fold), ifosfamide (3.5-fold), and thiotepa (3.9-fold). For cytarabine and thiopurines, the median LC50 values (the drug concentration that kills 5% of the cells) were equal. Also, busulfan, amsacrine, teniposide, and vindesine showed no significant differences, but the numbers were smaller, and the median LC50 values were 1.3- to 5.2-fold higher in AML. None of the drugs demonstrated greater cytotoxicity in AML. FAB M5 was significantly more sensitive than FAB M4 to most drugs frequently used in AML, as indicated by the following ratios of median sensitivities: the anthracyclines (2.6- to 3.2-fold), mitoxantrone (12.5-fold), etoposide (8.7-fold), and cytarabine (2.9-fold). For etoposide and cytarabine (5.4- and 3.4-fold, respectively) FAB M5 was also significantly more sensitive than FAB M1/M2. FAB M5 was equally sensitive to L-asparaginase and vincristine as ALL. Only 15% of the AML samples were "intermediately" sensitive to glucocorticoids, mainly in FAB M1/M2. The poorer prognosis of childhood AML is related to resistance to a large number of drugs. Within AML, FAB M5 had a distinct resistance pattern. These resistance profiles may be helpful in the rational design of further treatment protocols. (Blood. 2000;96:2879-2886)
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PMID:Cellular drug resistance profiles in childhood acute myeloid leukemia: differences between FAB types and comparison with acute lymphoblastic leukemia. 1102 25

To determine the incidence of leukemia-specific rearrangements, 60 cases of childhood acute myeloblastic leukemia and transient myeloproliferative disorder were screened with a novel multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) assay, and the results were correlated with the cytogenetic findings. The RT-PCR assay detects 28 different fusion genes and more than 80 different fusion transcript variants. RNA was isolated from methanol/acetic acid-fixed cells that had been routinely prepared for cytogenetic analysis. Nine different fusion transcripts were found in 40% of the cases, whereas 78.3% of the cases had abnormal karyotypes. Two cases with a t(6;11) and an MLL/AF6 gene fusion were missed cytogenetically. Conversely, cytogenetic analysis revealed 10 other well-defined chromosome rearrangements. Although cytogenetic analysis reveals a much broader range of abnormalities, multiplex RT-PCR serves as quality control and provides the essential information for minimal residual disease studies. Moreover, discrepant findings lead to the detection of new rearrangements on the molecular genetic level.
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PMID:Multiplex reverse transcriptase-polymerase chain reaction screening in childhood acute myeloblastic leukemia. 1115 1

To investigate the cumulative incidence of second malignancy and the competing risk of death due to any other cause in patients who were treated for childhood acute myeloid leukemia (AML), we analyzed the outcomes in a cohort of 501 patients who were treated at St Jude Children's Research Hospital between 1970 and 1996. Five patients developed a second cancer (two carcinomas of the parotid gland, one non-Hodgkin's lymphoma, one supratentorial primitive neuroectodermal tumor, one acute lymphoblastic leukemia) as compared with 0.47 expected in the general population (standardized incidence ratio, 10.64; 95% confidence interval, 3.28 to 22.34). A third neoplasm (meningioma) developed in one patient. At 15 years after the diagnosis of AML, the estimated cumulative incidence of second malignancy was 1.34% +/- 0.61%, whereas the cumulative incidence of death due to any other cause was 72.96% +/- 2.14%. We concluded that although a more than 10-fold increased risk of development of cancer was found in survivors of childhood AML as compared to the general population, the risk of this late complication is small when compared to the much larger risk of death because of the primary leukemia or the early complications of its treatment. Future studies should focus on improving treatments for primary AML while preventing second malignancies.
Leukemia 2001 Jan
PMID:Second malignancy after treatment of childhood acute myeloid leukemia. 1124 97

Acute myeloid leukaemia (AML) is thought to be methotrexate (MTX)-resistant. However, a small study suggested that acute monocytic leukemia (AML-M5) is sensitive to MTX. We measured MTX accumulation/polyglutamylation in 20 AML-nonM5, 37 AML-M5 and 83 common/preB-acute lymphoblastic leukaemia (c/preB-ALL) samples. Membrane transport was determined in 11 childhood AMLs (including 3 AML-M5) and in 25 c/preB-ALL samples. MTX sensitivity was determined in 23 AML-nonM5, 15 AML-M5 and 63 common/preB-ALL samples using the thymidylate synthase (TS) inhibition assay. MTX transport was higher in AML samples compared with c/preB-ALL precluding a transport defect in AML. Accumulation of long-chain polyglutamates MTX-Glu(4-6) was 3-fold lower for AML-nonM5 compared with c/preB-ALL cells (median 268 versus 889 pmol MTX-Glu(4-6)/10(9) cells; P < or = 0.001); for AML-M5 samples, median accumulation of MTX-Glu(4-6) was 0 pmol/10(9) cells (P < or = 0.001). After short-term MTX exposure, AML-nonM5 was 6-fold more resistant to MTX compared with c/preB-ALL cells (2.16 versus 0.39 microM; P < 0.001), while AML-M5 was 2-fold more resistant (P = 0.02). In both AML-nonM5 and AML-M5 cells, MTX resistance was circumvented by continuous MTX exposure (median TSI(50) values: 0.052 and 0.041 microM, respectively) compared with a c/preB-ALL value of 0.066 microM. In conclusion, AML-M5 is relatively sensitive to MTX compared with other AML-subtypes even though polyglutamylation of MTX is poor. Using continuous exposure, AML-nonM5 and AML-M5 cells were at least as sensitive to MTX as c/preB-ALL cells. This report suggests that MTX might be an overlooked drug in the treatment of childhood AML.
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PMID:A possible role for methotrexate in the treatment of childhood acute myeloid leukaemia, in particular for acute monocytic leukaemia. 1126 59

Tetrasomy 8 is a relatively rare chromosomal abnormality in hematological disorders, and is mostly associated with myeloid malignancies and poor prognosis. In a number of cases, tetrasomy 8 has been reported as an accompanying anomaly with other chromosomal changes. In this report, we describe a 14-year-old girl with acute megakaryoblastic leukemia associated with tetrasomy 8 (primary) and trisomy 6, 19 and 20. She died 6 months after diagnosis, suggesting a relatively poor prognosis for AML with tetrasomy 8. To the best of our knowledge, this is the first report of a tetrasomy 8 abnormality associated with subtype FAB M7. Interestingly, this abnormality has not been previously reported in childhood AML patients.
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PMID:Tetrasomy 8 as a primary chromosomal abnormality in a child with acute megakaryoblastic leukemia. a case report and review of the literature. 1137 11

An improved understanding of how leukemia cells grow and become resistant to treatment remains critical for developing more effective therapies. We have identified activating mutations of c-kit at codon 816 (Asp(816) ) from a revertant of the cytokine-dependent acute myeloid leukemia (AML) cell line, MO7e (D816H), and de novo childhood AML (D816N). Following transduction of the mutant c-kit cDNAs, MO7e cells acquire a growth advantage and resistance to apoptosis in response to chemotherapeutic drugs and ionizing radiation, in addition to cytokine-independent survival. Although stimulation of mutant c-kit-bearing MO7e cells with stem cell factor (SCF), a ligand for c-Kit, does not have a significant effect on cell proliferation, SCF further inhibits apoptosis induced by cytotoxic agents. These results suggest a potentially important role of Asp(816) mutations of c-kit in both malignant cell proliferation and resistance to therapy.
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PMID:Activating mutations of c-kit at codon 816 confer drug resistance in human leukemia cells. 1137 69

Childhood myeloid leukaemias are a diverse collection of conditions. Although many are also seen in adults, some are peculiar to childhood. In childhood AML, as in adults, cytogenetic abnormalities are associated with specific clinical features and define prognostic groups. In infants under 1 year with AML, the incidence of 11q23 abnormalities is particularly high. The finding of identical 11q23 breakpoints in infant leukaemia as in therapy-related leukaemias suggests a role for in utero exposure to topoisomerase II inhibitors. There are a number of constitutional disorders that predispose children to develop AML, usually with a preceding myelodysplastic phase. Monosomy (or deletion of the long arm) of chromosome 7 is the most frequent chromosome abnormality in the bone marrow of such patients. Abnormalities of chromosome 7 are also common cytogenetic findings in all morphological subgroups of childhood myelodysplasia, either as a primary abnormality or associated with disease progression.
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PMID:Childhood myeloid leukaemias. 1164 Aug 70

Granulocytic sarcoma is considered to be rare and its frequent occurrence is associated with specific genetic changes such as t(8;21). To investigate an association between MLL (mixed lineage leukemia or myeloid-lymphoid leukemia) rearrangement and granulocytic sarcoma, we applied fluorescence in situ hybridization for detection of the 11q23/MLL rearrangements on the bone marrow cells of 40 patients with childhood acute myelogenous leukemia (AML). Nine (22.5%) of 40 patients exhibited MLL rearrangements. Three (33.3%) of these nine patients had granulocytic sarcoma and were younger than 12 months of age. Of these three patients one presented as granulocytic sarcoma of both testes with cerebrospinal fluid involvement, the second case presented in the form of an abdominal mass, and the third as a periorbital granulocytic sarcoma. On the other hand, no granulocytic sarcomas were found among MLL-negative patients. It is likely that MLL-positive infant AML may predispose granulocytic sarcoma. Regarding the findings of our study and those of other reports, we would guess that the incidence of granulocytic sarcoma in pediatric MLL-positive AML may be equal to or greater than the 18 to 24% described in AML with t(8;21). Further investigations designed to identify 11q23/MLL abnormalities of leukemic cells or extramedullary tumor may be helpful for the precise diagnosis of granulocytic sarcoma.
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PMID:Granulocytic sarcoma in MLL-positive infant acute myelogenous leukemia: fluorescence in situ hybridization study of childhood acute myelogenous leukemia for detecting MLL rearrangement. 1173 51

Recent reports have established the prenatal origin of leukemia translocations and resultant fusion genes in some patients, including MLL-AF4 translocations in infants and TEL-AML1 translocations in children. We now report evidence for the prenatal origin of a translocation in childhood acute myeloid leukemia (AML). The t(8;21) AML1-ETO translocations were sequenced at the genomic level in 10 diagnostic leukemia samples from children with available neonatal Guthrie blood spots. Clonotypic genomic AML1-ETO sequences were detected in the Guthrie spots for 5 individuals, providing unambiguous evidence of prenatal origin in these cases. Two of these patients were older than 10 years of age at diagnosis, indicative of a protracted postnatal latency. Three of the patients were assessed for the persistence of genomic fusion sequences in complete clinical remission samples and were found to be positive. These data indicate that t(8;21) in childhood AML can arise in utero, possibly as an initiating event in childhood AML, and may establish a long-lived or stable parental clone that requires additional secondary genetic alterations to cause leukemia.
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PMID:In utero origin of t(8;21) AML1-ETO translocations in childhood acute myeloid leukemia. 1198 39

FLT3 is the most frequently mutated gene in cases of acute myelogenous leukemia (AML). About 30 to 35% of patients have either internal tandem duplications (ITDs) in the juxtamembrane domain or mutations in the activating loop of FLT3. FLT3 mutations occur in a broad spectrum of FAB subtypes in adult and pediatric AML and are particularly common in acute promyelocytic leukemia (APL). FLT3 mutations confer a poor prognosis in most retrospective studies. The consequence of either FLT3-ITD or activating loop mutations, which occur predominantly at position D835, is constitutive activation of the tyrosine kinase; FLT3 mutants confer factor-independent growth to Ba/F3 and 32D cells and activate similar transduction pathways as the native receptor in response to ligand, including the STAT, RAS/mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3; kinase (PI3K)/AKT pathways. Injection of FLT3-ITD transformed cells, such as Ba/F3 or 32D, into syngeneic recipient mice results in a leukemia-like syndrome, and expression in primary murine bone marrow cells in a retroviral transduction assay results in a myeloproliferative disorder. Mutations that abrogate FLT3 kinase activity result in loss of transforming properties in these assays. Further, FLT3-selective inhibitors impair transformation of primary AML cells that harbor these mutations, and also inhibit FLT3 transformed hematopoietic cell lines, and leukemias induced by activated FLT3 mutants in murine models. Collectively, these data indicate that FLT3 may be a viable therapeutic target for treatment of AML.
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PMID:Role of FLT3 in leukemia. 1204


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