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)

The B-cell lymphoma/leukemia-2 (bcl-2) proto-oncogene has been associated with the transformation of benign lesions to malignancy, disease progression, poor prognosis, reduced survival, and development of resistance to radiation and chemotherapy in many types of cancer. The objective of this work was to synthesize an antisense peptide nucleic acid (PNA) complementary to the first six codons of the bcl-2 open reading frame, conjugated to a membrane-permeating peptide for intracellular delivery, and modified with a bifunctional chelating agent for targeting imaging and therapeutic radiometals to tumors overexpressing bcl-2. Four peptide-PNA constructs were synthesized by a combination of manual and automated stepwise elongation techniques, including bcl-2 antisense conjugates and nonsense conjugates with no complementarity to any known mammalian gene or DNA sequence. The PNA sequences were synthesized manually by solid-phase 9-fluorenylmethoxycarbonyl (Fmoc) techniques. Then a fully protected lysine monomer, modified with 1,4,7,10-tetraazacyclododecane-N,N',N'',N'"-tetraacetic acid (DOTA) for radiometal chelation, was coupled manually to each PNA sequence. Synthesis of the DOTA-PNA conjugates was followed by automated elongation with a peptide sequence (PTD-4-glycine, PTD-4-G), known to mediate cellular internalization of impermeable effector molecules, or its retro-inverso analogue (ri-PTD-4-G). Preparation of the four conjugates required an innovative synthetic strategy, using mild acid conditions to generate hydrophobic, partially deprotected intermediates. These intermediates were purified by semipreparative reversed-phase HPLC and completely deprotected to yield pure peptide-PNA conjugates in 6% to 9% overall yield. Using modifications of this synthetic strategy, the ri-PTD-4-G conjugate of bcl-2 antisense PNA was prepared using a lysine derivative of tetramethylrhodamine (TMR) for fluorescence microscopy. Plasma stability studies showed that (111)In-DOTA-labeled ri-PTD-4-G-anti-bcl-2 PNA was stable for 168 h at 37 degrees C, unlike the conjugate containing the parent peptide sequence. Scanning confocal fluorescence microscopy of TMR-labeled ri-PTD-4-G-anti-bcl-2 PNA in Raji lymphoma cells demonstrated that the retro-inverso peptide was active in membrane permeation and mediated cellular internalization of the antisense PNA into the cytoplasm, where high concentrations of bcl-2 mRNA are expected to be present.
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PMID:Synthesis of radiometal-labeled and fluorescent cell-permeating peptide-PNA conjugates for targeting the bcl-2 proto-oncogene. 1462 21

In the present study 170 newly diagnosed acute promyelocytic leukaemia patients (M3: n = 121; M3v: n = 49) were molecularly characterised with respect to PML breakpoint and additional molecular mutations. In total, 83 patients were positive for bcr1 (49%), five for bcr2 (3%) and 82 for bcr3 (48%). Bcr3 was more frequent in M3v (65.3%) compared with M3 (41.3%) (P = 0.005). Cases with bcr3 showed a significantly higher white blood cell count (median: 3.65 x 10(9)/l vs. 1.59 x 10(9)/l, P = 0.003), as well as a higher PML-RARAABL expression ratio (14.8% vs. 72.7%, P < 0.005) compared with bcr1. FLT3-length-mutations were detected more frequently together with bcr3 compared with bcr1 (56.5% vs. 19.4%, P < 0.001) and in M3v compared with M3 (64.5% vs. 24.1%, P < 0.005). FLT3 tyrosine kinase mutations were found in eight cases (6.4%) and were distributed equally within the total group. Analysis for further mutations revealed no MLL-PTD and KIT mutations and only two cases of 99 analysed (2%) with NRAS mutations. FLT3-mutations were detected in 62 of 139 cases (44.6%) and associated with a significant lower overall survival (P = 0.0339). In addition, cases with bcr3 showed a tendency for a worse event-free survival (P = 0.0795) compared with the bcr1 group.
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PMID:Impact of FLT3 mutations and promyelocytic leukaemia-breakpoint on clinical characteristics and prognosis in acute promyelocytic leukaemia. 1602 47

The fusion transcripts of MLL rearrangement [MLL(+)] in acute myeloid leukemia (AML) and their clinicohematologic correlation have not be well characterized in the previous studies. We used Southern blot analysis to screen MLL(+) in de novo AML. Reverse transcriptase-polymerase chain reaction was used to detect the common MLL fusion transcripts. cDNA panhandle PCR was used to identify infrequent or unknown MLL partner genes. MLL(+) was identified in 114 (98 adults) of 988 AML patients. MLL fusion transcripts comprised of 63 partial tandem duplication of MLL (MLL-PTD), 14 MLL-AF9, 9 MLL-AF10, 9 MLL-ELL, 8 MLL-AF6, 4 MLL-ENL and one each of MLL-AF1, MLL-AF4, MLL-MSF, MLL-LCX, MLL-LARG, MLL-SEPT6 and MLL-CBL. The frequency of MLL-PTD was 7.1% in adults and 0.9% in children (P<0.001). 11q23 abnormalities were detected in 64% of MLL/t11q23 and in none of MLL-PTD by conventional cytogenetics. There were no differences in remission rate, event-free survival and overall survival between adult MLL-PTD and MLL/t11q23 groups. Adult patients had a significantly poorer outcome than children. The present study showed that cDNA panhandle PCR can identify all rare or novel MLL partner genes. MLL-PTD was rare in childhood AML. MLL(+) adults had a poor outcome with no difference in survival between MLL-PTD and MLL/t11q23 groups.
Leukemia 2006 Feb
PMID:Characterization of fusion partner genes in 114 patients with de novo acute myeloid leukemia and MLL rearrangement. 1634 Oct 46

AML-associated MLL-PTD contribute to leukemogenesis by a gain of function and confer an unfavorable prognosis. Like other leukemia associated aberrations they are also present in healthy adults. To delineate the leukemogenic mechanism we tracked down MLL-PTD in normal hematopoiesis and investigated cord blood samples. MLL-PTD were observed in 56/60 (93%) of all cord bloods. In contrast to AML, the transcript frequency in cord blood was four log scales lower as determined by real-time PCR. The CD34+ progenitor cell, CD33+ myeloid, CD19+ B-lymphoid and CD3+ T-lymphoid subfractions were positive. The ubiquitous presence of MLL-PTD in cord blood implicates a lifelong exposure, not an accumulation during lifetime. Since also present in the stem cell subfraction, these factors seem not to be major determinants in MLL-PTD leukemogenesis.
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PMID:Lifelong persistence of AML associated MLL partial tandem duplications (MLL-PTD) in healthy adults. 1654 Jan 67

Mixed lineage leukaemia gene-partial tandem duplications (MLL-PTD) characterise acute myeloid leukaemia (AML) with trisomy 11 and AML with a normal karyotype. MLL-PTD confer a worse prognosis with shortened overall and event free survival in childhood and adult AML. In spite of these clinical observations, the leukaemogenic mechanism has, so far, not been determined. This review summarises clinical studies on MLL-PTD positive AML and recent experimental findings on the putative leukaemogenic role of MLL-PTD.
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PMID:The MLL partial tandem duplication in acute myeloid leukaemia. 1696 85

The clinical impact of MLL partial tandem duplication (MLL-PTD) was evaluated in 238 adults aged 18 to 59 years with cytogenetically normal (CN) de novo acute myeloid leukemia (AML) who were treated intensively on similar Cancer and Leukemia Group B protocols 9621 and 19808. Twenty-four (10.1%) patients harbored an MLL-PTD. Of those, 92% achieved complete remission (CR) compared with 83% of patients without MLL-PTD (P=.39). Neither overall survival nor disease-free survival significantly differed between the 2 groups (P=.67 and P=.55, respectively). Thirteen MLL-PTD(+) patients relapsed within 1.4 years of achieving CR. MLL-PTD(+) patients who relapsed more often had other adverse CN-AML-associated molecular markers. In contrast with previously reported studies, 9 (41%) MLL-PTD(+) patients continue in long-term first remission (CR1; range, 2.5-7.7 years). Intensive consolidation therapy that included autologous peripheral stem-cell transplantation during CR1 may have contributed to the better outcome of this historically poor-prognosis group of CN-AML patients with MLL-PTD.
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PMID:Long-term disease-free survivors with cytogenetically normal acute myeloid leukemia and MLL partial tandem duplication: a Cancer and Leukemia Group B study. 1734 62

The chromosomal alterations at 11q23 that involve the mixed-lineage leukemia gene (MLL, HTRX1, HRX, ALL1) are one of the most common cytogenetic abnormalities in acute leukemia and have been associated with a poor prognosis. Given that not all MLL alterations are seen under conventional cytogenetics or fluorescence in situ hybridization (FISH), it is very important to use molecular techniques to determine the cause of alteration. In this study, we describe two cases of AML in which FISH analysis showed a high-level 11q23 amplification, to confirm if this overexpression may be accompanied by partial tandem duplication of the MLL gene (MLL-PTD). Both patients showed complex karyotype and an unfavorable clinical course. The 11q23 region characterization included conventional cytogenetics, FISH, and comparative genomic hybridization analysis to study the expression patterns of several oncogenes located within the amplified region and detection of partial tandem duplication of the MLL gene by reverse-transcription polymerase chain reaction (RT-PCR) and sequencing. MLL-PTD were detected in the two patients. Moreover, patient 1 showed amplification of the MLL flanking region. Our data suggest that molecular methods such as RT-PCR or sequencing should be used to detect MLL alterations, and that amplification of MLL locus may be extended to its flanking region.
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PMID:MLL amplification in acute myeloid leukemia. 1745 54

Almost half of adult acute myelogenous leukemia (AML) is normal cytogenetically, and this subgroup shows a remarkable heterogeneity of genetic mutations at the molecular level and an intermediate response to therapy. The finding of recurrent cytogenetic abnormalities has influenced, in a primary way, the understanding and treatment of leukemias. Yet "normal karyotype AML" lacks such obvious abnormalities, but has a variety of prognostically important genetic abnormalities. Thus, the presence of a FLT3-ITD (internal tandem duplication), MLL-PTD (partial tandem duplication), or the increased expression of ERG or EVI1 mRNAs confer a poor prognosis, and an increased risk of relapse. In contrast, the presence of cytoplasmic nucleophosmin or C/EBPA mutations is associated with lower relapse rates and improved survival. Although resistance to treatment is associated with specific mutations, the degree to which the leukemia resembles a stem cell in its functional properties may provide greater protection from the effects of treatment. Although usually all of the circulating leukemia cells are cleared following treatment, a small residual population of leukemic cells in the bone marrow persists, making this disease hard to eradicate. Increased understanding of the biological consequences of at least some of these mutations in "normal karyotype AML" is leading to more targeted approaches to develop more effective treatments for this disease.
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PMID:Is it important to decipher the heterogeneity of "normal karyotype AML"? 1834 11

Posttranslationally modified histones and DNA hypermethylation frequently interplay to deregulate gene expression in cancer. We report that acute myeloid leukemia (AML) with an aberrant histone methyltransferase, the mixed lineage leukemia partial tandem duplication (MLL-PTD), exhibits increased global DNA methylation versus AML with MLL-wildtype (MLL-WT; P = .02). Among the differentially methylated genes, the SLC5A8 tumor suppressor gene (TSG) was more frequently hypermethylated (P = .003). In MLL-PTD(+) cell lines having SLC5A8 promoter hypermethylation, incubation with decitabine activated SLC5A8 expression. Ectopic SLC5A8 expression enhanced histones H3 and H4 acetylation in response to the histone deacetylase inhibitor, valproate, consistent with the encoded protein-SMCT1-short-chain fatty acid transport function. In addition, enhanced cell death was observed in SMCT1-expressing MLL-PTD(+) AML cells treated with valproate. Within the majority of MLL-PTD AML is a mechanism in which DNA hypermethylation silences a TSG that, together with MLL-PTD, can contribute further to aberrant chromatin remodeling and altered gene expression.
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PMID:DNA hypermethylation and epigenetic silencing of the tumor suppressor gene, SLC5A8, in acute myeloid leukemia with the MLL partial tandem duplication. 1856 24

Certain leukemias have a high relapse risk even after allo-SCT, and GVHD prophylaxis with calcineurin inhibitors (CNIs) may interfere with a possible GVL effect. Therefore, we replaced CYA by sirolimus in patients with high relapse risk. In contrast to CNIs, sirolimus promotes the generation of regulatory T-cells and has potent antineoplastic activity. Sirolimus has been used in combination with CNI for GVHD prophylaxis in hematopoietic SCT. However, no CNI-free prophylactic regimen with sirolimus has been evaluated so far. Within the FLAMSA-RIC protocol, 15 patients received GVHD prophylaxis with sirolimus and mycophenolate mofetil (MMF). The underlying diagnoses were relapsed or refractory T-ALL (n=3), AML with FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) or mixed-lineage leukemia-partial tandem duplication (MLL-PTD; n=10; 5 with refractory disease) and CML in refractory myeloid blast crisis (n=2). All evaluable patients (n=14) were engrafted. Grades II-IV acute GVHD occurred in 21% and chronic GVHD in 30% of patients. Non-relapse mortality rate was 14%. No thrombotic microangiopathy or sinusoidal obstruction syndrome was observed. Three patients with FLT3-ITD+ AML relapsed after a median of 112 days. At a median follow-up of 10 months after transplantation, 10 patients are alive and in complete remission. In conclusion, sirolimus-based GVHD prophylactic regimens deserve further investigation.
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PMID:Calcineurin inhibitor-free GVHD prophylaxis with sirolimus, mycophenolate mofetil and ATG in Allo-SCT for leukemia patients with high relapse risk: an observational cohort study. 1901 60


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