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Query: UMLS:C0596978 (Leukemia)
 15,069 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twenty-seven patients with AML and MLL gene rearrangement were analyzed by a reverse transcriptase polymerase chain reaction (RT-PCR) for the MLL-AF9 translocation. The MLL-AF9 fusion transcript was detected in six patients. In five patients, the breakpoint of the AF9 gene was located within the recently described site A; in one patient, a novel breakpoint (AF9 site D) mapped to a position 377 bp 3' of site A. Five patients could be serially monitored for a period of 4-23 months. Two patients became two-step PCR negative in bone marrow and peripheral blood. Molecular remission was achieved rapidly after one cycle of induction chemotherapy. Both patients are in continuous complete remission (CR) at 22 and 15 months, respectively. Two patients who had achieved hematological CR did not become PCR negative and MLL-AF9 fusion transcripts were detectable in all samples after induction and consolidation chemotherapy. One patient relapsed 5 months after achieving CR. The other patient received allogeneic bone marrow transplantation from an HLA-identical sibling 2 months after achieving hematological CR and became PCR negative 4 weeks after transplantation. In the fifth patient, hematological CR could not be achieved with two cycles of intensive induction chemotherapy, and MLL-AF9 transcripts were present in all samples tested. Our data indicate that MLL-AF9 RT-PCR is specific for the t(9;11) translocation. PCR negativity can be achieved in responding patients already 1 month after induction chemotherapy. The fast reduction of MLL-AF9 positive blast cells below the detection limit of RT-PCR seems to be a prerequisite for long-term CR. The results of RT-PCR may be useful for treatment decisions (eg BMT).
Leukemia 1999 Oct
PMID:Monitoring of minimal residual leukemia in patients with MLL-AF9 positive acute myeloid leukemia by RT-PCR. 1051 52

Translocations affecting the chromosomal locus 11q23 are hallmarks of infant leukemias. These events disrupt the MLL gene (also ALL-1 or HRX) and fuse the MLL amino terminus in frame with a variety of unrelated proteins. The ENL gene on 19p13.1 is a recurrent fusion partner of MLL. Whereas potential functions have been suggested for isolated domains of either MLL or ENL no experimental data exist for the biological properties of the complete chimeric MLL-ENL protein. We show here that the fusion of MLL with ENL creates a novel molecule that is a potent general transcriptional transactivator in transient reporter gene assays. MLL-ENL strongly transactivated several unrelated promoters including the promoter of Hoxa7 a potential target gene for the unaltered MLL protein. This transactivation capability was cell type specific and it was critically dependent on the contributions of the methyltransferase-homology (MT) region of MLL in combination with the C-terminus of ENL. Squelching experiments and gel retardation studies identified the ENL C-terminus as a binding partner for an unknown factor and the MLL MT region as a unique general DNA binding motif. The potential implications of these findings for the leukemogenesis by MLL-ENL are discussed.
Leukemia 1999 Oct
PMID:The leukemogenic fusion of MLL with ENL creates a novel transcriptional transactivator. 1051 53

Bone marrow samples from 67 children with acute leukemia and with cytogenetic evidence of chromosome 11 band q23 (11q23) abnormalities were characterized by fluorescence in situ hybridization (FISH) and Southern blot analysis to determine whether FISH could reliably detect MLL gene rearrangements in this population. Among the 42 patients with acute lymphoblastic leukemia (ALL), MLL gene rearrangements were detected in cells from 23 patients (54.8%) by both FISH and Southern blot analysis. FISH identified allelic deletions of MLL gene in five of 12 patients (42%) with ALL and with deletion of 11q23. In 22 of 25 children (88%) with AML, FISH detected MLL gene rearrangements, whereas Southern blot analysis identified rearrangements in 24 of 25 patients (96%). For children with acute leukemia and with 11q23 abnormalities, we recommend that FISH be used for the rapid screening of MLL gene rearrangements and that Southern blot analysis be used for the definitive assessment of the MLL gene status.
Leukemia 1999 Nov
PMID:Comparison of cytogenetics, Southern blotting, and fluorescence in situ hybridization as methods for detecting MLL gene rearrangements in children with acute leukemia and with 11q23 abnormalities. 1055 43

Prospective studies on the detection of minimal residual disease (MRD) in acute leukemia patients have shown that large-scale MRD studies are feasible and that clinically relevant MRD-based risk group classification can be achieved and can now be used for designing new treatment protocols. However, multicenter international treatment protocols with MRD-based stratification of treatment need careful standardization and quality control of the MRD techniques. This was the aim of the European BIOMED-1 Concerted Action 'Investigation of minimal residual disease in acute leukemia: international standardization and clinical evaluation' with participants of 14 laboratories in eight European countries (ES, NL, PT, IT, DE, FR, SE and AT). Standardization and quality control was performed for the three main types of MRD techniques, ie flow cytometric immunophenotyping, PCR analysis of antigen receptor genes, and RT-PCR analysis of well-defined chromosomal aberrations. This study focussed on the latter MRD technique. A total of nine well-defined chromosome aberrations with fusion gene transcripts were selected: t(1;19) with E2A-PBX1, t(4;11) with MLL-AF4, t(8;21) with AML1-ETO, t(9;22) with BCR-ABL p190 and BCR-ABL p210, t(12;21) with TEL-AML1, t(15;17) with PML-RARA, inv (16) with CBFB-MYH11, and microdeletion 1p32 with SIL-TAL1. PCR primers were designed according to predefined criteria for single PCR (external primers A <--> B) and nested PCR (internal primers C <--> D) as well as for 'shifted' PCR with a primer upstream (E5' primer) or downstream (E3' primer) of the external A <--> B primers. The 'shifted' E primers were designed for performing an independent PCR together with one of the internal primers for confirmation (or exclusion) of positive results. Various local RT and PCR protocols were compared and subsequently a common protocol was designed, tested and adapted, resulting in a standardized RT-PCR protocol. After initial testing (with adaptations whenever necessary) and approval by two or three laboratories, the primers were tested by all participating laboratories, using 17 cell lines and patient samples as positive controls. This testing included comparison with local protocols and primers as well as sensitivity testing via dilution experiments. The collaborative efforts resulted in standardized primer sets with a minimal target sensitivity of 10-2 for virtually all single PCR analyses, whereas the nested PCR analyses generally reached the minimal target sensitivity of 10-4. The standardized RT-PCR protocol and primer sets can now be used for molecular classification of acute leukemia at diagnosis and for MRD detection during follow-up to evaluate treatment effectiveness.
Leukemia 1999 Dec
PMID:Standardized RT-PCR analysis of fusion gene transcripts from chromosome aberrations in acute leukemia for detection of minimal residual disease. Report of the BIOMED-1 Concerted Action: investigation of minimal residual disease in acute leukemia. 1060 11

The MLL gene on chromosome 11 band q23 is frequently involved in chromosome translocations in acute lymphoblastic leukemia and acute myeloid leukemia. The translocation results in the formation of a fusion gene on the derivative 11 chromosome consisting of the 5' part of the MLL gene and the 3' part of another gene; already more than 30 different partner chromosome regions have been described. MLL gene rearrangements are generally correlated with a poor prognosis. Therefore the presence of an 11q23 aberration has direct implications for treatment stratification, making early and rapid detection of utmost importance. In this study, we developed a FISH probe set for detection of MLL gene rearrangements according to strict design criteria. The cosmid probes are derived from the flanking regions of the MLL breakpoint region on chromosome 11 and when used in dual colored FISH experiments give rise to a split of the normally colocalizing (fused) signals in case of a translocation. This split signal was observed in seven out of 10 cases with an 11q23 translocation with various partner chromosomes. In the three other cases, a deletion of the 3' part of the MLL gene, downstream of the breakpoint region was also found. A low false positive value of only 1.7% was obtained for interphase cells in contrast to conventional dual colored FISH where the creation of a fusion signal has cut off values of at least 5-10%. A major advantage of our type of probe set is the application of a single FISH experiment to detect all types of MLL translocations. Moreover, since this cosmid probe set can be used for either interphase or metaphase studies, metaphases are no longer a prerequisite for detecting the presence of an 11q23 translocation. Nevertheless, metaphase FISH with the new probe set is helpful in determining the partner chromosome and therefore may lead to the identification of new partner genes.
Leukemia 1999 Dec
PMID:Rapid and sensitive detection of all types of MLL gene translocations with a single FISH probe set. 1060 37

The t(10;11)(p12-p13;q14-q21) observed in a subset of patients with either acute lymphoblastic leukemia or acute myeloid leukemia has been shown to result in the fusion of AF10 on chromosome 10 with CALM (also named CLTH) on chromosome 11. AF10 was originally identified as a fusion partner of MLL in the t(10;11)(p12-p13;q23) observed in myeloid leukemia. CALM is a newly isolated gene, cloned as the fusion partner of AF10 in the monocytoid cell line, U937. In order to understand the relationship between MLL, AF10, CALM and the leukemic process, fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction were used to study a series of nine leukemia patients with a t(10;11). Six had myeloid leukemia (AML-M0, AML-M1, AML-M4 and AML-M5) and three had T cell lymphoblastic leukemia. We identified four different CALM/AF10 fusion products in five patients and AF10/CALM reciprocal message in one. We conclude that fusion of CALM and AF10 is a recurring abnormality in both lymphoid and myeloid leukemias of various types including AML-M5, and that the breakpoints in the two types of leukemia do not differ. Our data indicate that the CALM/AF10 fusion product on the der(10) chromosome is critical to leukemogenesis. Leukemia (2000) 14, 100-104.
Leukemia 2000 Jan
PMID:Identification and molecular characterization of CALM/AF10fusion products in T cell acute lymphoblastic leukemia and acute myeloid leukemia. 1063 83

The mixed lineage leukaemia gene, MLL (also called HRX, ALL-1) in acute leukaemia is fused to at least 16 identified partner genes that display diverse structural and biochemical properties. Using GST pull down and the yeast two hybrid system, we show that two different MLL fusion partners with SH3 domains, EEN and Abi-1, interact with dynamin and synaptojanin, both of which are involved in endocytosis. Synaptojanin, a member of the inositol phosphatase family that has recently been shown to regulate cell proliferation and survival, is also known to bind to Eps15, the mouse homologue of AF1p, another fusion partner of MLL. Expression studies show that synaptojanin is strongly expressed in bone marrow and immature leukaemic cell lines, very weakly in peripheral blood leukocytes and absent in Raji, a mature B cell line. We found that the SH3 domains of EEN and Abi-1 interact with different proline-rich domains of synaptojanin while the EH domains of Eps15 interact with the NPF motifs of synaptojanin. In vitro competitive binding assays demonstrate that EEN displays stronger binding affinity than Abi-1 and may compete with it for synaptojanin. These findings suggest a potential link between MLL fusion-mediated leukaemogenesis and the inositol-signalling pathway.
Leukemia 2000 Apr
PMID:The interaction between EEN and Abi-1, two MLL fusion partners, and synaptojanin and dynamin: implications for leukaemogenesis. 1076 44

Partial tandem duplications of the MLL gene have been associated with trisomy 11 in acute myeloid leukemia (AML) and recently, have also been reported for karyotypically normal AML. In order to test the incidence and prognostic importance of this molecular marker, we have analyzed eight cases of AML with trisomy 11 and 387 unselected consecutive cases with AML for partial duplications of the MLL gene. Patients with normal karyotypes and those with various chromosome aberrations were included. De novo as well as secondary leukemias including all FAB subtypes were analyzed. Performing a one-step RT-PCR with 35 cycles using an exon 9 forward primer and an exon 3 reverse primer partial tandem duplications of the MLL gene were demonstrated in 3/8 (37.5%) patients with trisomy 11. In addition, 13/387 (3.4%) of unselected cases revealed a tandem duplication. Ten of these 13 cases were cytogenetically normal, the other three cases had < or =2 additional chromosomal alterations. Sequencing of the RT-PCR products of all 16 positive cases revealed fusions of MLL exon 9/exon 3 (e9/e3) (six cases), e10/e3 (three cases), e11/e3 (four cases) or combinations of differentially spliced e10/e3 and e11/e3 (three cases) transcripts. The duplications were confirmed by genomic long range PCR and Southern blot hybridization. Twelve cases with the MLL duplication were de novo myeloid leukemia, one was a secondary AML after MDS, three were therapy-related AML (t-AML). Of the 16 MLL-duplication positive cases, seven were classified as FAB M2, two as M1, five as M4, one as M0, one as M5b. The mean age was 62.3 years for patients with MLL duplication vs 50.3 years for the control group. Of 15 adult patients, 12 received treatment. Of these, three were nonresponders, five had early relapse (< or =6 months), four relapsed between 7 and 12 months. Median survival and relapse-free interval of the MLL duplication positive group was significantly worse than those of an age-matched karyotypically normal control group. In conclusion, MLL tandem duplications (1) are less common than previously reported; (2) are preferentially observed in AML with normal karyotypes, but can also be found in the presence of chromosome alterations; (3) are not strongly associated with an FAB subtype; (4) were not observed with the prognostically favorable t(8;21), inv(16), and t(15;17), other recurrent translocations, or in complex karyotypes; and (5) identifies a subgroup of patients with an unfavorable prognosis.
Leukemia 2000 May
PMID:Screening for MLL tandem duplication in 387 unselected patients with AML identify a prognostically unfavorable subset of AML. 1080 9

MLL gene rearrangements are associated with coexpression of myeloid- and lymphoid-associated antigens on leukemic blasts and a dismal outcome in acute lymphoblastic leukemia (ALL). Whether the same conditions can apply to acute myeloid leukemia (AML) is not quite clear. Rearrangements of the MLL gene were analyzed on 113 patients with newly diagnosed de novo AML in a single institution. Sixteen (14%) of them showed rearranged bands by Southern blot analysis, including three (50%) of six infants, three (14%) of 21 children between 1 and 15 years and 10 (12%) of 86 adults. MLL rearrangements were not only detected in M5 (four of 12 patients, 33%) and M4 (six of 31, 19%) subtypes but also in other non-M4-M5 AML (six of 70, 9%), including M1, M2 and M7, but not M3 subtype. Seven patients had chromosomal abnormalities involving 11q23, but nine did not. The latter comprised three (6%) of 48 patients with normal karyotype, one with t(8;21), none with t(15;17), inv(16) or t(9;22), and four (15%) of 27 with cytogenetic aberrations other than those specific structural abnormalities. In contrast to ALL, AML patients with MLL rearrangements did not tend to coexpress lymphoid- and myeloid-associated antigens simultaneously on leukemic blasts and have similar outcome as those without the gene rearrangements.
Leukemia 2000 Jun
PMID:Characterization of acute myeloid leukemia with MLL rearrangements--no increase in the incidence of coexpression of lymphoid-associated antigens on leukemic blasts. 1086 68

The MLL gene, located at 11q23, is frequently rearranged in acute leukaemia as either chimaeric fusion genes or partial tandem duplications. We report a series of 12 acute leukaemia cases with apparent amplification of the MLL gene ascertained using fluorescence in situ hybridisation (FISH). Seven cases showed intrachromosomal amplification of MLL, four cases showed extrachromosomal amplification as double minute chromosomes (dmin) and one case had separate subclones with dmin and homogenously staining region (hsr). Southern blot analysis of the MLL gene showed MLL gene rearrangement in three of the 10 successful cases. These cases do not naturally fall into either of the two recognised categories of MLL rearrangement and may represent a third variety of MLL gene abnormalities.
Leukemia 2000 Nov
PMID:MLL amplification in acute leukaemia: a United Kingdom Cancer Cytogenetics Group (UKCCG) study. 1106 23


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