Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report the clinical, hematologic, cytogenetic, and molecular characteristics of 13 patients with Philadelphia-negative (Ph-), bcr-negative atypical chronic myelogenous leukemia (CML). In the majority of cases, the phenotypic features at presentation resembled those of typical CML. However, these patients presented with a higher median age, lower median hemoglobin levels, and lower leukocyte and platelet counts than patients with Ph-positive CML. Cytogenetic analysis showed an abnormal karyotype in only one case. Southern blot investigation, using probes exploring the entire M-bcr region, demonstrated the absence of genomic bcr-abl rearrangements. The assessment of clonality in five patients (study of X-methylation patterns in females heterozygous at the DXS255 locus) indicated the proliferation of a monoclonal cell population. Disease evolution was mostly characterized by bone marrow failure, extramedullary infiltrates, and poor response to chemotherapy, without evidence of overt acute transformation. Our observations suggest that some hematologic and clinical features and the modalities of disease progression are presently the most helpful factors in distinguishing these bcr/abl-negative patients from those with typical bcr+CML. The differences existing also with chronic myelomonocytic leukemia (CMMoL), allow the consideration of ph-/bcr- CML as a separate entity, the nature of which remains to be elucidated.
 ...
PMID:Ph-negative and bcr-negative atypical chronic myelogenous leukemia: biological features and clinical outcome. 164 55

Karyotype and bcr/abl recombinant DNA analyses are two means of detecting the chromosomal aberration in chronic myeloid leukemia. The authors compared these two methods in a retrospective study of 36 patients with CML in which they found the bcr/abl DNA recombinant event in 100% (29 of 29) of those patients who had the Philadelphia chromosome. To achieve this sensitivity, a battery of two bcr probes and three restriction enzymes is necessary. The authors propose a sequential algorithm for efficient use of these probes and enzymes. In 76% of the patients, bcr/abl rearrangement can be detected with a Bgl II digest and a 3' commercial probe. An additional 21% of patients can be detected by a second assay in which the same membrane is rehybridized to a 3' and 5' combination bcr probe. One patient (3%) required an additional restriction enzyme digest with BamH I to detect the recombinant event by the same 3' probe. Karyotype analysis is used to determine cytogenetic remission in patients with CML under therapy. The authors studied the use of DNA analysis by the Southern blot technique to detect a decrease in the relative number of leukemic cells. By dilution studies and densitometric scanning of autoradiographs, the authors were able to detect a 15% decrease in the relative number of cells having the bcr/abl recombinant event. The authors report the preliminary results of three patients in whom they compared the karyotype and recombinant DNA analysis at multiple time points in their clinical course. In conclusion, the bcr/abl recombinant DNA analysis is superior to karyotype for the diagnosis of CML and can be used for monitoring treated patients.
 ...
PMID:Bcr/abl recombinant DNA analysis versus karyotype in the diagnosis and therapeutic monitoring of chronic myeloid leukemia. 169 6

Chronic myelogenous leukemia and one type of acute lymphoblastic leukemia are characterized by a 9;22 chronosome translocation in which 5' sequences of the bcr gene become fused to the c-abl proto-oncogene. The resulting chimeric genes encode bcr/abl fusion proteins which have deregulated tyrosine kinase activity and appear to play an important role in induction of these leukemias. A series of bcr/abl genes were constructed in which nested deletions of the bcr gene were fused to the c-abl gene. The fusion proteins encoded by these genes were assayed for autophosphorylation in vivo and for differences in subcellular localization. Our results demonstrate that bcr sequences activate two functions of c-abl; the tyrosine kinase activity and a previously undescribed microfilament-binding function. Two regions of bcr which activate these functions to different degrees have been mapped: amino acids 1 to 63 were strongly activating and amino acids 64 to 509 were weakly activating. The tyrosine kinase and microfilament-binding functions were not interdependent, as a kinase defective bcr/abl mutant still associated with actin filaments and a bcr/abl mutant lacking actin association still had deregulated kinase activity. Modification of actin filament functions by the bcr/abl tyrosine kinase may be an important event in leukemogenesis.
 ...
PMID:Activation of tyrosinase kinase and microfilament-binding functions of c-abl by bcr sequences in bcr/abl fusion proteins. 170 8

We have studied the effect of a replication-defective murine retroviral vector expressing the chronic myelogenous leukemia associated oncoprotein p210bcr/abl in murine IL-3 dependent myeloid 32D C13(G) cells. This cell line can be induced to differentiate along either the granulocytic or monocytic lineages thus permitting an independent assessment of the effect of p210bcr/abl on growth and differentiation. Cells expressing p210bcr/abl displayed a complete non-autocrine abrogation of IL-3 dependence and an enhanced response to an activity in FBS which is not IGF-I or IGF-II. During the first few generations following infection with the bcr/abl vector, cells became larger with an increased fraction of cells in G2/M and monocyte/macrophage markers were expressed. Four cytoplasmic proteins phosphorylated in response to IL-3 in the parental cell line with apparent molecular weights of 98, 70, 62, and 52 Kd were amongst those constitutively phosphorylated in p210bcr/abl expressing cells. These results suggest that the functional substitution of IL-3 by p210bcr/abl is due to constitutive activation of proteins involved in IL-3 signal transduction. Alterations of cell differentiation, cell cycle and growth which cannot be attributed to IL-3 like effects indicate that p210bcr/abl has pleiotropic effects involving several other pathways of cellular regulation.
 ...
PMID:Expression of the chronic myelogenous leukemia-associated p210bcr/abl oncoprotein in a murine IL-3 dependent myeloid cell line. 170 88

Although rare cells expressing the bcr/abl fusion transcript can be detected by the polymerase chain reaction (PCR) in patient blood or marrow after allogeneic bone marrow transplant (BMT) for Philadelphia chromosome (Ph+)-positive chronic myelogenous leukemia (CML), the prognostic significance of this finding is unknown. This paper reports clinical, cytogenetic, and molecular data derived from 64 CML patients following allogeneic BMT. Nested primer PCR was performed on patient blood and bone marrow samples to detect the presence of residual bcr/abl (+) cells in CML patients considered to be in clinical remission at the time of study. Bcr/abl transcripts were detected in 37 of 64 patients for at least one timepoint post-BMT. Thirteen of these 37 bcr/abl (+) patients have subsequently relapsed, as defined by clinical and/or persistent cytogenetic findings, in contrast to 0 relapses among the 27 bcr/abl (-) patients (P = .0025). The median time from first (+) bcr/abl PCR signal to relapse was 150 days (range 90 to 832). Fifty-four patients were studied at two or more timepoints post-BMT: five of eight patients persistently bcr/abl (+) have relapsed; 5 of 23 patients with both bcr/abl (+) and (-) assays during follow-up have relapsed; and none of 23 patients persistently (-) have relapsed (cumulative actuarial relapse rates 77%, 20%, and 0%, respectively, P = .0017). These data indicate that among CML patients in apparent clinical remission after BMT, nested primer bcr/abl PCR can define subgroups with low, intermediate, and high risk of relapse. The pattern of bcr/abl PCR detection after transplant may aid in the development of trials designed to reduce the risk of relapse, or allow for early intervention in patients who fail to clear the malignant clone.
 ...
PMID:Prognostic significance of Philadelphia chromosome-positive cells detected by the polymerase chain reaction after allogeneic bone marrow transplant for chronic myelogenous leukemia. 172 16

We have utilized the polymerase chain reaction (PCR) to sensitively detect persistence of the chronic myelogenous leukemia (CML) malignant clone and to study bcr/abl mRNA splicing patterns following bone marrow transplantation. Thirteen of sixteen patients displayed persistent malignant cells during post-BMT clinical remission. In two patients bcr/abl mRNA was detected 4 and 9 months prior to clinical relapse. In eleven of fourteen patients in continued clinical remission malignant cells were detected post-BMT. Ten of these eleven patients were also cytogenetically normal. Seven patients have lost all evidence of bcr/abl transcript, but only at 1-2 years posttransplant, while four have shown persistence of the bcr/abl transcript from 28 days to 3 years post-BMT and one has converted from an initially negative result at 1 year post-BMT to detectable levels of chimeric mRNA at 2 years. Thus, 8/9 patients tested at or before 6 months, 7/12 at 1 year, and 3/10 at 2 years showed persistent detectable CML cells. Intriguingly, mRNA splicing patterns changed in 5 patients following BMT, with complete loss of mRNA containing bcr exon 3 (n = 2) or new appearance of mRNA not containing bcr exon 3 (n = 2). A single patient transiently lost evidence of bcr exon 3 expression while persistently expressing the bcr exon 2/abl exon 2 splice. Our data suggest that the majority of patients harbor small numbers of malignant cells following transplantation, and that such persistence may not inevitably predict clinical relapse. Complete elimination of the malignant CML clone post-BMT may rely on immunological mechanisms (e.g., graft-vs-leukemia).
 ...
PMID:bcr/abl mRNA detection following bone marrow transplantation for chronic myelogenous leukemia. 175 65

A patient with chronic myelogenous leukemia (CML) associated with pure red cell aplasia (PRCA) is reported. The occurrence of PRCA has been described previously in sporadic cases of Philadelphia chromosome (Ph) positive CML. In this patient, however, the Ph-chromosome was not detected; cytogenetic analysis revealed a t(12;14)(q23;p11) as the sole abnormality. Molecular studies by Southern and PCR analyses showed the rearrangement of the BCR and ABL sequences and expression of the chimeric bcr/abl mRNA, thus confirming the diagnosis of CML. To our knowledge, this is the first report on a case of PRCA associated with Ph negative CML at diagnosis. The possible connection between CML and PRCA is discussed.
 ...
PMID:Pure red cell aplasia in a case of Ph negative BCR/ABL rearranged CML with t(12;14)(q23;p11). 175 63

The P210bcr/abl protein is produced in cells from patients with Philadelphia chromosome-positive chronic myelogenous leukemia (CML). Retroviral transfer of the gene encoding P210bcr/abl into murine bone marrow induces a granulocytic leukemia that models the chronic phase of human CML. We have transferred the leukemic clone to syngeneic animals, albeit with surprising inefficiency, and have observed CML and clonally related acute leukemias of lymphoid or myeloid phenotype in some transplant recipients. These data show that murine CML can result from retroviral transfer of the bcr/abl gene into pluripotent hematopoietic stem cells, that infected clones repopulate poorly after adoptive transfer, and that these clones can give rise to acute leukemia, reflecting evolution to a phase resembling blast crisis in the human disease.
 ...
PMID:Blast crisis in a murine model of chronic myelogenous leukemia. 176 47

Two bcr/abl fusion gene products with tyrosine kinase activity have been found in two phenotypes of Philadelphia chromosome (Ph1)-positive leukemia. P210bcr/abl (P210) is associated with Ph1-positive chronic myelogenous leukemia (CML), while P190bcr/abl is associated with Ph1-positive acute leukemia. We compared the susceptibility of 32Pi-labeled P210 from K-562 cells and P190 from MR-87 cells to protein tyrosine phosphatase (PTPase). PTPase, present in the lysate of mature granulocytes from CML patients as well as in the lysate of these cells from normal subjects, effectively dephosphorylated the CML-associated P210 and the acute leukemia associated P190. This PTPase activity was specifically inhibited by ZnCl2; it was not present in lymphocyte lysates, and was not inhibited by neutralization with anti-CD45 antibody. Since P210 and P190 were equally sensitive to the PTPase, the difference in leukemic phenotypes associated with the expression of these two tyrosine kinases cannot be explained by the differential dephosphorylation of P210 and P190.
 ...
PMID:Two bcr/abl fusion gene products, P210bcr/abl and P190bcr/abl, are equally sensitive to the protein tyrosine phosphatase of mature granulocytes. 179 29

Recent contributions from molecular biology, biotechnology and recombinant DNA applications have led to important clinical and therapeutic advances in chronic myelogenous leukemia (CML). Developments in the methodology of genetic investigation have clarified the molecular alterations brought about by the appearance of the Philadelphia chromosome. It is possible that the hybrid bcr/abl gene plays an important role in the pathogenesis of CML by subverting the mechanism of homeostasis through the uncoordinated activation of cell growth stimulating and regulating factors. Further improvements have been brought about by the polymerase chain reaction (PCR) which permits an indirect identification of the fusion gene and the study of minimal residual disease during remission after chemotherapy and bone marrow transplantation (BMT). Clinical trials have shown that alpha-interferon, alone or in association with chemotherapy, induces long term clinical and cytogenetic remission in those CML patients in whom BMT from either related or unrelated donors cannot be performed. Allogeneic BMT seems to be the treatment of choice in younger people. However, since a minority of subjects have HLA identical siblings, the possibility of using unrelated donors to provide long term disease free survival has been explored even if the availability of a compatible donor is the primary limiting factor. The development of in vivo and in vitro purging procedures has aroused new interest in autologous bone marrow transplantation. This procedure benefits particularly from biotherapeutic agents which selectively act on the marrow by suppressing bcr/abl positive cells.
 ...
PMID:Chronic myelogenous leukemia: state of the art. 184 Aug 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>