Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the myeloperoxidase (MPO) gene at the mRNA level is a better lineage marker than enzymatic activity in early myeloid precursors and their leukemic counterparts. Its diagnostic use depends on the specificity of expression for myeloblasts and its absence in blasts of lymphoid lineage. The present study investigates MPO mRNA expression in adult acute lymphoblastic leukemia (ALL), using reverse transcription-polymerase chain reaction. Of a total of 13 cases, six were found to have blasts positive for MPO mRNA; in all of these cases, the blasts were cytochemically negative for MPO. This unexpected finding of MPO mRNA positivity in six of 13 cases was further investigated at the molecular level. Bcr gene rearrangement analysis was positive in all six cases for the bcr breakpoint diagnostic of chronic myelogenous leukemia (CML). Only three of these six cases were cytogenetically positive for a Philadelphia (Ph) chromosome. Based on molecular analysis, these cases are considered as CML presenting in blast crisis of lymphoid lineage, as opposed to de novo ALL. The remaining seven cases were Ph negative at the cytogenetic and molecular levels; the leukemic blasts were MPO mRNA negative, confirming the lack of MPO gene expression in de novo ALL.
Diagn Mol Pathol 1996 Dec
PMID:Myeloperoxidase mRNA analysis in acute lymphoblastic leukemia. 927 91

BCR-ABL is a chimaeric oncogene generated by translocation of sequences from the c-ABL protein-tyrosine kinase gene on chromosome 9 into the BCR gene on chromosome 22. Alternative chimeric proteins, p210(BCR-ABL) and p190(BCR-ABL), are produced that are characteristic of chronic myelogenous leukemia and acute lymphoblastic leukemia, respectively. Their role in the aetiology of human leukemia remains to be defined. We have previously shown that the tumorigenic effect of BCR-ABL oncogenes is mediated by Bcl-2. In addition to Bcl-2, is a protein essential for transformation by BCR-ABL. However, it is not known how Bcl-2 and Ras fit together in cell transformation by BCR-ABL. The data presented here establish that Bcl-2 is a downstream target gene of the Ras signalling pathway in cells transformed by BCR-ABL, and that constitutive Ras activation results in constitutive expression of the gene. Conversely, a truncated form of the BCR-ABL, which lacks a critical BCR region required for activation of the Ras signalling pathway, failed to induce Bcl-2 expression. These results indicate that BCR-ABL prevents apoptosis by inducing Bcl-2 through a signalling pathway involving Ras and links constitutive Ras activation and Bcl-2 gene regulation. Hence, these results further imply that Ras is involved in both mitogenic signals and survival signals.
J Mol Biol 1997 Mar 28
PMID:Regulation of Bcl-2 gene expression by BCR-ABL is mediated by Ras. 909 20

Cellular accumulation of methotrexate polyglutamates (MTXPGs) is recognized as an important determinant of the cytotoxicity and selectivity of methotrexate in acute lymphoblastic leukemia (ALL). We identified a significantly lower cellular accumulation of MTXPGs in T-lineage versus B-lineage lymphoblasts in children with ALL, which is consistent with the worse prognosis of T-lineage ALL when treated with conventional antimetabolite-based therapy. Maximum MTXPG accumulation in leukemic blasts in vivo was 3-fold greater in lymphoblasts of children with B-lineage ALL (129 children) compared with those with T-lineage ALL (20 children) (p < 0.01) and was characterized by a saturable (Emax) model in both groups. The human leukemia cell lines NALM6 (B-lineage) and CCRF/CEM (T-lineage) were used to assess potential mechanisms for these lineage differences in MTX accumulation, revealing i) greater total and long-chain MTXPG accumulation in NALM6 over a wide range of methotrexate concentrations (0.2-100 microM), ii) saturation of MTXPG accumulation in both cell lines, with a higher maximum (Emax in NALM6, iii) 3-fold higher constitutive FPGS mRNA expression and enzyme activity in NALM6 cells, iv) 2-fold lower levels of DHFR mRNA and protein in NALM6 cells, and v) 4-6 fold lower extracellular MTX concentration and 2-fold lower intracellular MTXPG concentration to produce equivalent cytotoxicity (LC50) in NALM6 versus CEM. There was a significant relationship between FPGS mRNA and enzyme activity in lymphoblasts from children with newly diagnosed ALL, and blast FPGS mRNA and activity increased after methotrexate treatment. These data indicate higher FPGS and lower DHFR levels as potential mechanisms contributing to greater MTXPG accumulation and cytotoxicity in B-lineage lymphoblasts.
Mol Pharmacol 1997 Jul
PMID:Differences in folylpolyglutamate synthetase and dihydrofolate reductase expression in human B-lineage versus T-lineage leukemic lymphoblasts: mechanisms for lineage differences in methotrexate polyglutamylation and cytotoxicity. 922 25

Four different detection systems were compared for evaluation of polymerase chain reaction (PCR) amplified immunoglobulin heavy-chain gene rearrangements in acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL) of B-cell lineage. In 63.0% of the fragments detected by ethidium bromide stained agarose gel electrophoresis (Agarose-EtBr) the sensitivity was insufficient to separate the specific clonal population from the background of normal B cells. Using polyacrylamide gel electrophoresis (PAGE), PAGE combined with single-strand conformation polymorphism (PAGE-SSCP) and PhastGel-SSCP (Phast-SSCP) analysis with silver staining, the resolution was improved and the majority of the inconclusive amplicons were elucidated. However, Phast-SSCP displayed a slightly higher detection level compared to PAGE and PAGE-SSCP. According to our findings PAGE-SSCP and Phast-SSCP were superior to agarose-EtBr and PAGE in detecting new emerging clones and clonal evolution.
Diagn Mol Pathol 1997 Jun
PMID:Comparative analysis of detection systems for evaluation of PCR amplified immunoglobulin heavy-chain gene rearrangements. 927 85

The complementarity determining region (CDR) III of the immunoglobulin heavy-chain (IgH) gene is a tumor-specific marker for B-cell malignancies that has been widely exploited for the monitoring of minimal residual disease in B-precursor acute lymphocytic leukemia. There are a number of technical problems in applying the same technology for B-cell non-Hodgkin's lymphoma (B-NHL). Several procedures have been useful in overcoming these unique problems encountered in obtaining the tumor-specific sequence of the IgH-CDRIII in B-NHL, including the use of denaturing gradient gel electrophoresis or micromanipulation of tissue sections in separating the tumor-specific CDRIII products from those of contaminating normal B-lymphocytes. Minor modifications of a commercial kit greatly improve the purity of the polymerase chain reaction (PCR) products for sequencing. Modifications of the 5'-ends of the VH and IH primers, coupled with the cycle sequencing technique, make it possible to obtain unambiguous sequences on direct sequencing of short PCR products. Computer informatics and programs that facilitate the design of tumor-specific primers and probes from CDRIII sequences are described.
Diagn Mol Pathol 1997 Jun
PMID:Obtaining clone-specific primer and probe for the immunoglobulin heavy-chain gene from paraffin-embedded tissue of B-cell lymphoma: technical considerations. 964 37

The polymerase chain reaction (PCR) has been applied to detect occult leukemia (ALL) cells in patients with acute lymphoblastic leukemia who are otherwise considered in complete remission by traditional morphological examination of bone marrow specimens. The combined data from the clinical studies published to date suggest that a consistent pattern for residual disease disappearance over many months exists for patients who remain in complete remission for an extended period of time. Conversely, a pattern of residual disease persistence and reappearance preceding clinical findings exists for the majority of patients who ultimately relapse. The ability to detect residual ALL disease near the end of chemotherapy or after the completion of treatment in some patients who otherwise are deemed likely to be cured of their malignancy raises the possibility that mechanisms other than leukemia cell cytotoxicity are influencing the outcome for this disease.
Cytokines Mol Ther 1995 Mar
PMID:Monitoring residual disease in acute lymphoblastic leukemia: therapeutic implications. 938 65

Management of acute lymphoblastic leukemia (ALL) patients may include growth factors (GFs) to reduce post-chemotherapy aplasia. A potential risk of GF administration is a stimulatory signal on the leukemic population. In the present study we investigated the proliferative and programmed cell death (PCD) effect of two cytokines that have recently entered clinical use, stem cell factor (SCF) and the granulocyte colony stimulating factor/IL-3 fusion molecule (PIXY-321), on 14 ALL samples. The activity of IL-7, a cytokine involved in the regulation of ALL cell proliferation, was also tested alone and in combination with these two cytokines. Using the acridine orange flow cytometric technique and the clonogenic assay, we showed that none of these cytokines was capable of significantly increasing the mean percentage of S-phase cells and CFU-L number. A mean decrease of G0 cells from 60.6% to 52.6% (p = 0.02), coupled by a significant increase of G1 cells from 28.2% to 37.9% (p = 0.003) was demonstrated in the presence of PIXY-321. IL-7 alone and in combination with either PIXY-321 or SCF induced similar changes in the percentage of cells in G0 and G1. SCF showed no activity on G0 depletion. When each individual samples was analyzed separately, some heterogeneity was observed. An increase of S phase was recorded in a proportion of cases after SCF and PIXY-321 exposure. However, none of the cytokines evaluated by a clonogenic assay following liquid culture was capable of maintaining or promoting self-renewal of leukemic precursors, as determined by plating fresh cells at time 0. Detection of cytokine effects of apoptosis showed that SCF and PIXY-321 did not significantly reduce the mean percentage of cells in PCD, whereas a significant protective effect was observed in the presence of IL-7 (p = 0.02). We conclude that PIXY-321 and, to a further extent, SCF fail to induce leukemic lymphoid cell proliferation, and do not protect cells from entering apoptosis. These in vitro findings may be useful for ALL clinical trial design.
Cytokines Mol Ther 1996 Dec
PMID:Stem cell factor and PIXY-321 in acute lymphoblastic leukemia: in vitro study on proliferative effects and apoptosis. 938 8

The chimeric Bcr-Abl oncogene has been implicated in the pathogenesis of chronic myelogenous leukemia (CML) and Philadelphia chromosome (Ph1)-positive acute lymphocytic leukemia (ALL). The Bcr-Abl protein is a complex structure comprising discrete domains associated with specific biochemical and biological functions. These domains function through their ability to activate distinct signal transduction pathways responsible for Bcr-Abl's oncogenic behavior. This review will present our current understanding of signal transduction pathways involved in Bcr-Abl-induced pathophysiology, with particular emphasis on potential targets for therapeutic intervention.
Cytokines Mol Ther 1996 Dec
PMID:Molecular mechanisms of Bcr-Abl-induced oncogenesis. 938 12

Aggregation of cell surface receptors plays an important role in signal transduction in many receptor systems. In the T cell receptor (TCR), as in many other cell surface receptors, this aggregation results in insolubility in certain nonionic detergents. We have characterized this insolubility for TCR, and we show it is not preexisting in HPB-ALL cells but increases with increasing TCR aggregation. It is not likely to be due to a direct interaction with cellular cytoskeletal elements, as it is not affected by inhibitors of actin or tubulin polymerization. It may be due to interaction with detergent-resistant membrane domains that have been found in various cell types and contain tyrosine kinases, the earliest known participants in TCR signal transduction. This aggregation-dependent insolubility occurs as rapidly as the anti-TCR antibody binds, so the kinetics are consistent with an involvement in signal transduction. It is not, however, dependent on signal transduction, as inhibitors of tyrosine kinases do not inhibit the insolubility. Insolubility is also enhanced by preaggregation of CD4, an important T cell surface molecule which also associates with the tyrosine kinase p56lck.
Mol Immunol
PMID:Characterization of the detergent insolubility of the T cell receptor for antigen. 946 31

Over the last three decades, acute lymphoblastic leukemia (ALL) of childhood has turned from a once fatal condition into a disease that can be cured in about two-thirds of patients. Nevertheless, about 30% of these children relapse with a dismal prognosis. Achievement of complete remission is an essential step in successful therapy. However, patients in complete remission as defined by morphologic criteria can still harbor more than 10(9) leukemic cells. We have recently shown that residual disease is detected in most patients after completion of therapy. The amount of persistent 'indolent' disease that is actually present in a particular patient and the degree to which it must be reduced to maintain a long-term remission is largely unknown. In order to address this question, and hence to tailor efficient therapy in accordance with the needs of the individual patient, a multitude of techniques for the detection of residual disease have been developed over the last few years. The most commonly used techniques are the polymerase chain reaction (PCR) assays. These sensitive assays have revolutionized this area of research. The heterogeneity of the results obtained, however, still precludes widespread clinical applicability of these techniques.
Cytokines Cell Mol Ther 1998 Jun
PMID:Residual disease in acute lymphoblastic leukemia of childhood: methods of detection and clinical relevance. 968 Dec 46


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