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Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

With the eventual goal of developing a treatment for chronic myelogenous leukemia (CML), attempts have been made to design hammerhead ribozymes that can specifically cleave BCR-ABL fusion mRNA. In the case of L6 BCR-ABL fusion mRNA (b2a2 type; BCR exon 2 is fused to ABL exon 2), which has no effective cleavage sites for conventional hammerhead ribozymes near the BCR-ABL junction, it has proved very difficult to cleave the chimeric mRNA specifically. Several hammerhead ribozymes with relatively long junction-recognition sequences have poor substrate-specificity. Therefore, we explored the possibility of using newly selected DNA enzymes that can cleave RNA molecules with high activity to cleave L6 BCR-ABL fusion (b2a2) mRNA. In contrast to the results with the conventional ribozymes, the newly designed DNA enzymes, having higher flexibility for selection of cleavage sites, were able to cleave this chimeric RNA molecule specifically at sites close to the junction. Cleavage occurred only within the abnormal BCR-ABL mRNA, without any cleavage of the normal ABL or BCR mRNA. Thus, these chemically synthesized DNA enzymes seem to be potentially useful for application in vivo , especially for the treatment of CML, if we can develop exogenous delivery strategies.
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PMID:Comparison of the specificities and catalytic activities of hammerhead ribozymes and DNA enzymes with respect to the cleavage of BCR-ABL chimeric L6 (b2a2) mRNA. 922 7

Chronic myeloid leukemia is a clonal stem cell disorder associated with the Philadelphia (Ph) translocation [t(9;22) (q34;q11)]. As a result of the Ph translocation, parts of the ABL and BCR genes become fused. Cytogenetic quantification of Ph+ metaphases can be used to monitor patient response to treatment but is of limited sensitivity and applies only to cycling cells. Fluorescence in situ hybridization (FISH) with probes from the BCR and ABL regions can also identify the Ph translocation in interphase cells. Established systems for the detection of fusion genes by FISH rely on colocalization of two different probes but are associated with a high rate of false-positive results. We have introduced a third probe labeled with a different fluorochrome to create a triple-probe/three-color system that permits identification of both the Ph chromosome and the derivative 9 chromosome in Ph+ cells. This system was used to determine the frequency of interphase cells carrying the BCR-ABL fusion gene in bone marrow and peripheral blood granulocytes from patients showing variable cytogenetic responses to interferon. Our data show that the triple-probe/three-color approach allows highly sensitive detection of residual disease. Moreover, this method is readily applicable to the analysis of other chromosome translocations.
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PMID:Improved sensitivity of BCR-ABL detection: a triple-probe three-color fluorescence in situ hybridization system. 926 56

This article discusses briefly the molecular consequences of the BCR-ABL fusion gene. It then reviews the current evidence supporting the notion that chronic myelogenous leukemia in its chronic phase is a clonal, hematopoietic, stem cell disease in which malignant hematopoietic stem and progenitor cells respond to "normal" external proliferation and differentiation stimuli, but in which such responses are altered owing to defects in the stem and progenitor cells as a result of the BCR-ABL oncogene.
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PMID:Stem cells in chronic myelogenous leukemia. 944 47

In situ reverse transcription (RT)-polymerase chain reaction (PCR) is a promising laboratory tool for biomedical investigation at the molecular level in tissues. Direct in-cell amplification of the breakpoint cluster region (BCR)-Abelson (ABL) fusion transcript of chronic myeloid leukemia (CML) has recently been accomplished in Italy using bone marrow mononuclear cell suspensions. The goals of this study are to determine if in situ RT-PCR amplification is possible on bone marrow spirate smears and to demonstrate any unique factors in this procedure. A commercially available method was used because of the existence of published protocols for adaptation. Bone marrow (BM) aspirate smears (n = 17) from patients with CML in blast crisis (positive case material) or other hematological malignancies (negative case material) were evaluated. Satisfactory amplification of the BCR-ABL fusion transcript occurred, and distinct blue cytoplasmic granules that varied in intensity were found in most CML blasts. The negative case materials lacked the specifically amplified granular signals. Overall signal strength and backgrounds were readily affected by the quality of the specimen as well as by changes in assay parameters. In conclusion, the direct in situ RT-PCR technique is applicable for bone marrow aspirate smear evaluation. However, it remains an investigative tool until optimization for sensitivity, specificity, and accuracy can be achieved.
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PMID:Applicability of direct in situ reverse transcription-polymerase chain reaction on bone marrow smears. 951 83

For the treatment of chronic myelogenous leukemia (CML), attempts have been made to design hammerhead ribozymes that can specifically cleave BCR-ABL fusion mRNA. In the case of L6 BCR-ABL fusion mRNA (b2a2 type), which has no effective cleavage sites for conventional hammerhead ribozymes near the BCR-ABL junction, it has proved very difficult to cleave the chimeric mRNA specifically. Several hammerhead ribozymes with relatively long junction-recognition sequences have poor substrate-specificity. Therefore, we explored the possibility of using DNA enzymes, that was newly selected by Santoro & Joyce and that can cleave RNA molecules with high activity, to cleave of L6 BCR-ABL fusion (b2a2) mRNA. By contrast to the results with the conventional ribozymes, the newly designed DNA enzymes, having higher flexibility for selection of cleavage sites, were able to cleave this chimeric RNA molecule specifically at sites close to the junction, without any cleavage of the normal ABL or BCR mRNA.
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PMID:Comparison of activities between hammerhead ribozymes and DNA enzymes targeted to L6 BCR-ABL chimeric (b2a2) mRNA. 958 75

Human chronic myelogenous leukemia (CML) is characterized by a translocation between chromosomes 9 and 22 that results in a BCR-ABL fusion gene coding for chimeric proteins. The junctional region of the BCR-ABLb3a2 molecule represents a potential leukemia-specific antigen which could be recognized by cytotoxic T lymphocytes (CTL). In fact, we identified a junctional nonapeptide (SSKALQRPV) which binds to HLA-A2.1 molecules. This peptide, as well as those binding to HLA-A3, -A11, and -B8 molecules (previously identified by others), elicits primary CTL responses in vitro from PBLs of both healthy donors and CML patients. Such CTL recognize HLA-matched, BCR-ABL-positive leukemic cells, implying efficient natural processing and presentation of these junctional peptides. Specific CTL were found at high frequency in 5 of 21 CML patients, suggesting that these epitopes are, to some extent, immunogenic in vivo during the course of the disease. These peptides could be useful for the development of specific immunotherapy in CML patients.
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PMID:Cytotoxic T cell response against the chimeric p210 BCR-ABL protein in patients with chronic myelogenous leukemia. 959 85

Second primary cancers represent an important complication of modern chemotherapy and radiotherapy. Therapy-related (tr) leukemias are among the most common second malignancies in both pediatric and adult populations. Whereas a reasonable amount of data is available regarding the epidemiology, molecular pathogenesis, clinical behavior and response to therapy of second primary acute leukemias, very little is known about therapy-related chronic myeloid leukemia (tr-CML). A better characterization of this entity could increase our understanding about the mechanisms of carcinogenesis, specially the induction of specific genetic abnormalities, e.g., BCR-ABL fusion, following chemotherapy and/or radiotherapy exposure, could facilitate the investigation of the kinetics of the development of CML, and also provide a model to study molecular events that might precede its development. Review of 32 tr-CML cases suggests that there are no clinically appreciable differences between tr-CML and de novo CML cases. Analysis of large epidemiological studies that investigated the risk of second primary leukemias has not shown any clear evidence of a higher risk of CML among individuals who underwent treatment for a primary cancer over the general population. The cancer-predisposing syndromes, the detection of BCR-ABL transcripts in healthy individuals, and the induction in vitro of BCR-ABL fusions by ionizing radiation, are all discussed in the context of tr-CML. Finally, the need for a large epidemiological study to specifically assess the risk of developing second primary CML after chemotherapy and/or radiotherapy is stressed.
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PMID:Therapy-related chronic myeloid leukemia: an epidemiological, clinical and pathogenetic appraisal. 963 72

Cytogenetic, interphase fluorescent in situ hybridization (FISH) and RT-PCR methods were used to study minimal residual disease in peripheral blood stem cells collected for autografting in three chronic myeloid leukemia (CML) patients in sustained complete cytogenetic remission after treatment with interferon alpha (IFNalpha). Karyotypic analysis failed to reveal Ph-positive metaphases. FISH detected 9-16% nuclei with a BCR-ABL fusion gene, contrasting with RT-PCR, performed in two cases, which was negative in one case and weakly positive in the other. RT-PCR was also subsequently weakly positive in the third patient. This discrepancy suggests that the BCR-ABL genomic rearrangement persists unexpressed in quiescent cells. These preliminary results, which need to be confirmed in larger series, suggest that monitoring residual disease in CML should be performed both at DNA and RNA levels. Moreover, autografting following IFNalpha therapy should be considered with caution because of the persistence of the BCR-ABL genomic rearrangement in a sizeable proportion of the cells.
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PMID:Does BCR-ABL genomic rearrangement persist in CML patients in complete remission after interferon alpha therapy? 966 93

In vitro studies have provided little consensus on the kinetic abnormality underlying the myeloid expansion of chronic myelogenous leukemia (CML). Transplantation of human CML cells into non-obese diabetic mice with severe immunodeficiency disease (NOD/SCID mice) may therefore be a useful model. A CML cell line (BV173) and peripheral blood cells collected from CML patients in chronic phase (CP), accelerated phase (AP), or blastic phase (BP) were injected into preirradiated NOD/SCID mice. Animals were killed at serial intervals; cell suspensions and/or tissue sections from different organs were studied by immunohistochemistry and/or flow cytometry using antihuman CD45 monoclonal antibodies (MoAbs), and by fluorescence in situ hybridization (FISH) for the BCR-ABL fusion gene. One hour after injection, cells were sequestered in the lungs and liver, but 2 weeks later they were no longer detectable in either site. Similar short-term kinetics were observed using 51Cr-labeled cells. The first signs of engraftment for BV173, AP, and BP cells were detected in the bone marrow (BM) at 4 weeks. At 8 weeks the median percentages of human cells in murine marrow were 4% (range, 1 to 9) for CP, 11% (range, 5 to 36) for AP, 38.5% (range, 18 to 79) for BP, and 54% (range, 31 to 69) for BV173. CP cells progressively infiltrated BM (21%) and spleen (6%) by 18 to 20 weeks; no animals injected with the cell line or BP cells survived beyond 12 weeks. The rate of increase in human cell numbers was higher for BP (7.3%/week) as compared with CP (0.9%/week) and AP (0. 5%/week). FISH analysis with BCR and ABL probes showed that some of the human cells engrafting after injection of CP cells lacked a BCR-ABL gene and were presumably normal. We conclude that CML cells proliferate in NOD/SCID mice with kinetics that recapitulate the phase of the donor's disease, thus providing an in vivo model of CML biology.
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PMID:The kinetics and extent of engraftment of chronic myelogenous leukemia cells in non-obese diabetic/severe combined immunodeficiency mice reflect the phase of the donor's disease: an in vivo model of chronic myelogenous leukemia biology. 969 28

The t(9;22) translocation resulting in the fusion of BCR and ABL genes is pathognomonic in chronic myeloid leukemia (CML) and may be investigated at the molecular level using fluorescence in situ hybridization (FISH). Two-color BCR-ABL probes visualizing one fusion signal (1F FISH) have high false positive rates (FPR) and false negative rates (FNR). The FPR is a result of the random spatial association of probe signals within normal interphase cells so that some cells appear to contain the BCR-ABL fusion gene. The FNR of 1F FISH probes depends on the distance between the BCR and ABL probes hybridized to the BCR-ABL fusion gene (< or =368 kb); the "gap" between the signals causing the cell to be interpreted as normal. To overcome these difficulties, a two-color probe was used, employing four yeast artificial chromosome (YAC) sequences that span the breakpoint regions of the BCR and ABL genes and that visualize the two fusion signals BCR-ABL and ABL-BCR in CML cells (2F FISH). The FNR for the 2F FISH probes was assessed on clonal Ph+ granulocyte-macrophage-colony-forming cell (CFU-GM) derived colonies and was reduced to 0.4% (2/450), compared with an FNR of 13.5% (111/823) with 1F FISH. The FPR in normal mononuclear cells for the 2F FISH was 0. 19 +/- 0.12% (3/1,700), whereas the FPR using 1F FISH was 4.5 +/- 2.3% (63/1,294). The 2F FISH can thus be used to evaluate very small frequencies of BCR-ABL-positive and -negative interphase cells and may be of use in the clinical monitoring of CML.
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PMID:A two-color BCR-ABL probe that greatly reduces the false positive and false negative rates for fluorescence in situ hybridization in chronic myeloid leukemia. 973 13


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