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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The major consequence of the formation of the Philadelphia (Ph1) chromosome characteristic of leukemia cells of patients with chronic myelogenous leukemia (CML) is fusion of c-abl and bcr genes. Using a sensitive RNase protection technique, we analyzed mRNA from a large number of CML patients. In most, we identified one or both species of bcr-abl chimeric transcripts. These two mRNAs vary in the specific bcr exon joined to abl exon II and are translated into slightly different proteins. The amounts of the fused mRNA within leukemia cells vary considerably between individuals and do not correlate with the phase of the disease.
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PMID:bcr-abl RNA in patients with chronic myelogenous leukemia. 310 69

Oncogene activation induced by chromosomal changes is now regarded as one of the most important phenomena during carcinogenesis. We have reported c-abl activation in a rat leukemia cell line K3D, caused by a secondary chromosomal translocation. Another erythroblastic leukemia cell line D5A1, originally derived from a leukemia induced by 7,12-dimethylbenz(a)anthracene (DMBA) in a Long-Evans rat, is characterized by a marker chromosome 1q+, which also probably occurred as a secondary change. In this cell line, the transcription level of Ha-ras related mRNA increased compared with other cell lines. By the in situ hybridization technique, the c-Ha-ras locus was assigned to 1q43 and the breakpoint 1q+. Because the breakpoint was so near the c-Ha-ras locus on the chromosome, the present system may provide a model of activation of the c-Ha-ras gene brought about by chromosomal translocation.
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PMID:Chromosome marker and enhanced expression of c-Ha-ras in a DMBA-induced erythroleukemia cell line (D5A1). 311 19

Activation of the oncogenic potential of c-abl proto-oncogene has been correlated with the activation of its tyrosine kinase activity. The oncogenes derived from c-abl, e.g., gag/v-abl in Abelson murine leukemia virus or bcr/abl in chronic myelogenous leukemia, lack N-terminal coding sequences of the normal c-abl gene. In mouse and human cells, two sets of N-terminal amino acids encoded by 5'-variable exons are found in c-abl proteins. To assess the importance of N-terminal deletion in the activation of c-abl tyrosine kinase, a full length or an N-terminal deleted c-abl protein was expressed in bacteria and in monkey COS cells. Measurements of the autokinase activity of these two c-abl proteins showed that deletion of the N-terminal amino acids led to a three to five fold increase of the c-abl tyrosine kinase activity. Thus, the N-terminal deletion is important in the activation of c-abl proto-oncogene.
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PMID:Negative regulation of c-abl tyrosine kinase by its variable N-terminal amino acids. 314 98

Tumor-specific alterations in oncogenes are thought to play a central role in the development of cancer. An example is the consistent fusion of the bcr gene to the c-abl oncogene on the Ph chromosome in CML. The Ph chromosome can also be observed in ALL. About 50% of Ph+ ALL cases, in contrast to CML, do not exhibit chromosomal breakpoints in the major cluster region or mcr (Ph+ mcr- ALL). These cases may have a novel bcr-abl fusion gene instead. We tested this hypothesis in eight Ph+ mcr- ALL patients by amplifying the putative hybrid part of the bcr-abl cDNA, using the polymerase chain reaction method. All cases examined showed the same joining of the first exon of the bcr gene to the c-abl oncogene. Thus, the novel bcr-abl fusion in Ph+ mcr- ALL is the result of a molecularly distinct Ph chromosome. This allows the definition of Ph+ leukemias by their respective bcr-abl oncogene activation. Moreover, the cDNA amplification method we use is a clinically useful tool to screen for bcr-abl oncogene activations in leukemia patients.
Leukemia 1988 Oct
PMID:bcr-abl oncogene activation in Philadelphia chromosome-positive acute lymphoblastic leukemia. 317 39

DNA of peripheral blood or bone marrow leukocytes from 8 normal subjects, 7 cases of acute lymphocytic leukemia (ALL), 2 of acute myelogenous leukemia (AML) and 1 of chronic myelogenous leukemia (CML), having been digested by endonuclease Eco RI or Pst I separately, was hybridized with the probes of 3' fragment (Pst I/Hind III) or 5' fragment (Hinc II/Pst I) of Abelson murine leukemia virus (A-MuLV) oncogene v-abl. The proto-oncogene c-abl, which is homologous to v-abl, was found amplified in 4 ALL, 1 CML and 1 AML. In one of these 4 ALL, c-abl was amplified even over 100 times. A new c-abl BamH I fragment with 6.7 kilobase pairs (kb) in length was observed in 2 ALL and 1 CML out of these 6 cases with amplification, but none of this fragment was found in the normal subjects or other leukemia patients. These 3 patients with the presence of 6.7 kb fragment were high risk ones and 2 of them had died, suggesting that 6.7 kb fragment be the index of poor prognosis. The amplification and rearrangement of c-abl imply the activation of proto-oncogene in leukemogenesis.
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PMID:[Amplification and rearrangement of proto-oncogene c-abl in human leukemia cells]. 321 75

We report a case of acute leukemia in which studies at presentation showed both myeloid and lymphoid cell surface markers. At relapse membrane markers studies were consistent with a leukemia of B-lymphoid lineage. However, immunoglobulin (Ig) and T cell receptor (TCR) beta chain genes were both found in a rearranged configuration. The majority of metaphases from the leukemic cells at presentation showed the Philadelphia chromosome, t(9;22)(q34;q11), whereas a minority were normal. At relapse both Ph-positive and -negative metaphases were still present in the bone marrow but some of the Ph-negative metaphases had acquired an additional chromosome #19 [47,XY, + 19]. Southern analysis of DNA from leukemic bone marrow cells at diagnosis showed no rearrangement of breakpoint cluster region (bcr). There was no bcr-abl chimeric mRNA typical of Ph-positive chronic myeloid leukemia (CML). However, the cells expressed an abl-related protein of Mr 190 kd with enhanced tyrosine kinase activity. Leukemic cell metaphases were studied by the technique of in situ hybridization with probes for C-lambda, sis, abl, and 5' bcr. The c-abl probe mapped to chromosome 22q11 in Ph-positive metaphases. The 5' bcr probe mapped to 9q+ in the Ph-positive metaphases and the C-lambda gene mapped to the Ph chromosome. Thus, the genomic breakpoint in this patient must lie upstream of the BCR defined by study of Ph-positive CML and downstream of the C-lambda gene locus. We speculate that the Ph-negative cells in this patient may represent a leukemic proliferation susceptible to acquisition of specific chromosomal changes.
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PMID:The genomic breakpoint in a patient with Philadelphia-positive acute leukemia is 5' of the breakpoint cluster region. 325 55

Six patients with Philadelphia-positive (Ph1+) acute nonlymphocytic leukemia (ANLL) were studied by morphological, immunological, cytogenetic, and molecular techniques. Seven Ph1+ acute lymphocytic leukemia (ALL) cases were also studied for comparison. Three of ANLL cases were classified in M1, M2, and M4 groups of the FAB nomenclature, while the three other cases do not fit with any FAB subgroup and are described as M0. Immunophenotypical marker studies, double immunolabeling, and combined immunological and cytogenetic studies of metaphases showed that these ANLL expressed several lineage differentiation antigens. Rearrangements of immunoglobulin heavy chain gene (C mu) were detected in the six ANLL cases and in the seven ALL cases studied, as well as, in most cases, rearrangement of T cell receptor beta chain genes and/or T cell rearranging gamma genes. The results favored the assumption that the Ph1 translocation originated from a multipotent stem cell in Ph1+ ANLL. A common t(9;22) translocation was found in all cases, and additional chromosomal abnormalities were present in the six ANLL cases and in five of the seven ALL cases. Molecular studies of bcr gene configuration and c-abl transcription allowed two groups of Ph1+ ANLL to be distinguished. Three cases had bcr rearrangement and c-abl mRNA expression comparable to those reported in Ph1+ chronic myeloid leukemia, while three others had not detectable bcr rearrangement and a 7.2-7.5 kb c-abl mRNA. The existence of Ph1+ ALL with and without classical bcr rearrangement was confirmed.
Leukemia 1988 May
PMID:Philadelphia-positive acute leukemia: lineage promiscuity and inconsistently rearranged breakpoint cluster region. 337 67

Cellular oncogenes have been localized at the breakpoints of characteristic chromosomal rearrangements occurring in certain hematologic malignancies. This has been reported to result in aberrant expression of the involved oncogenes. Over 90% of chronic myelogenous leukemia (CML) is characterized by a reciprocal translocation that brings c-abl from chromosome 9 to chromosome 22, and c-sis from chromosome 22 to chromosome 9. To investigate the possible role of these two oncogenes in the leukemic process, we studied their expression in a number of fresh samples obtained from patients with various forms of leukemia, by Northern blot analysis using c-onc probes. Seven of 24 samples obtained from patients with either CML or chronic myelomonocytic leukemia expressed a normal 4.0-kilobase (kb) c-sis transcript. C-sis expression was found only in the accelerated/blast phases but not in the chronic phase of CML. All of the CML Philadelphia chromosome-positive (Ph1+) samples expressed an aberrant 8-kb c-abl transcript. The expression of c-sis in
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PMID:C-sis and C-abl expression in chronic myelogenous leukemia and other hematologic malignancies. 345 50

Localization of cellular oncogenes (c-onc) near the break points of translocations in tumor cells has indicated involvement of these genes in neoplastic growth. Enhanced transcription of the cellular homolog (c-abl) of the transforming sequence of Abelson murine leukemia virus was observed in K3D, which was one of the cloned cell lines of 7,12-dimethylbenz[a]anthracene-induced rat erythroblastic leukemia. Since the c-abl activation was not observed in the parent cell line (K2D) from which K3D was derived and the latter was different from the former in the presence of a new marker chromosome, t(3;12), this marker may play a role in the expression of c-abl in K3D cells. In contrast to the human c-onc assignments, few rat c-onc assignments have been reported. In situ molecular hybridization studies assigned c-abl to the 3q12 site of the normal chromosome 3 and to the break point of the translocation t(3;12) in K3D cells. Another break point in this translocation chromosome 12p11 involves the nucleolar region, and the 3;12 translocation may involve c-abl and nucleolar cistrons. These results provide evidence of secondary c-onc activation during karyotypic evolution of cloned malignant cells.
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PMID:Secondary activation of c-abl may be related to translocation to the nucleolar organizer region in an in vitro cultured rat leukemia cell line (K3D). 345 63

The cytogenetic, hematologic, and clinical characteristics of a 13-year-old girl with acquired t(6;9)(p23;q34) and dysmyelopoietic syndrome developing into acute myelomonocytic leukemia are described, bringing the total number of patients with t(6;9) and hematologic disease described in the literature up to 19. The diagnosis has been acute myeloid leukemia in the great majority of these patients; only four have had acute myelomonocytic leukemia. High resolution analysis at the 550 band stage localized the breakpoints in chromosomes #6 and #9 to p23 and 9q34.3, respectively. Previous investigations employing high resolution cytogenetics have mapped the typical 9q breakage site in chronic myeloid leukemia to 9q34.1. In situ hybridization studies have demonstrated that the cellular oncogene c-abl remains on the derivative 9q+ chromosome in t(6;9), whereas it is moved to the Ph marker in t(9;22). Thus, the combined data indicate that c-abl is located between 9q34.1 and 9q34.3, i.e., in subband 9q34.2 or its immediate vicinity.
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PMID:High resolution banding analysis of the reciprocal translocation t(6;9) in acute nonlymphocytic leukemia. 345 23


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