Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A patient with a chronic myeloproliferative disease associated with a 100% t(5;12) translocation was treated with 3 million U per day of IFN-alpha 2a. Besides being consistently Ph-negative, the search for BCR/ABL hybrid transcripts by means of RT-PCR was also negative. Total cytogenetic conversion to diploid hematopoiesis was obtained, but after discontinuation of IFN a 50% relapse of t(5;21) mitoses was found, and treatment was resumed. There is some degree of consensus that the mechanism by which IFN-alpha suppresses the Ph+ clone in CML consists in the restoration of normal adhesion of CML progenitors to the marrow stroma, by preventing transcription of the BCR/ABL mRNA, and hence expression of the p210 tyrosine kinase. However, if the 'faulty adhesion' hypothesis, and its correction by IFN-alpha, is to be considered correct, this case proves that it must include also Ph-negative, not BCR-ABL rearranged clonal myeloid proliferations.
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PMID:Chronic clonal myeloproliferative disease associated with a t(5;21) translocation. Complete but transient hematologic and cytogenetic remission induced by interferon-alpha. 759 88

The BCR/ABL oncogenic tyrosine kinase is responsible for initiating and maintaining the leukemic phenotype of Philadelphia chromosome (Ph1)-positive cells. Phosphatidylinositol-3 (PI-3) kinase is known to interact with and be activated by receptor and nonreceptor tyrosine kinases. We investigated whether PI-3 kinase associates with and/or is regulated by BCR/ABL, whether this interaction is functionally significant for Ph1 cell proliferation, and, if so, whether inhibition of PI-3 kinase activity can be exploited to eliminate Ph1-positive cells from bone marrow. We show that the p85 alpha subunit of PI-3 kinase associates with BCR/ABL and that transient expression of BCR/ABL in fibroblasts and down-regulation of BCR/ABL expression using antisense oligodeoxynucleotides (ODNs) in Ph1 cells activates and inhibits, respectively, PI-3 kinase enzymatic activity. The use of specific ODNs or antisense constructs to downregulate p85 alpha expression showed a requirement for p85 alpha subunit in the proliferation of BCR/ABL-dependent cell lines and chronic myelogenous leukemia (CML) primary cells. Similarly, wortmannin, a specific inhibitor of the enzymatic activity of the p110 subunit of PI-3 kinase, inhibited growth of these cells. The growth of normal bone marrow and erythromyeloid, but not megakaryocyte, progenitors was inhibited by p85 alpha antisense [S]ODNs, but wortmannin, at the concentrations tested, did not affect normal hematopoiesis. The proliferation of two BCR/ABL- and growth factor-independent cell lines was not affected by downregulation of the expression of the p85 alpha subunit or inhibition of p110 enzymatic activity, confirming the specificity of the observed effects on Ph1 cells. Thus, PI-3 kinase is one of the downstream effectors of BCR/ABL tyrosine kinase in CML cells. Moreover, reverse transcriptase-polymerase chain reaction performed on single colonies to detect BCR-ABL transcripts showed that wortmannin was able to eliminate selectively CML-blast crisis cells from a mixture of normal bone marrow and Ph1 cells.
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PMID:Phosphatidylinositol-3 kinase activity is regulated by BCR/ABL and is required for the growth of Philadelphia chromosome-positive cells. 760 2

The cell line AR230 was established from the peripheral blood mononuclear cells of a patient with chronic myeloid leukemia and t(9;22) translocation bearing a variant type of BCR/ABL rearrangement. AR230 expresses a BCR/ABL fusion protein with a molecular mass of 230 kilodaltons (kDa) due to the insertion of 180 amino acids encoded by 3' exons of BCR (b4 to c3). An immune complex kinase assay showed that the 230-kDa BCR/ABL protein ahd autophosphorylation activity. Immunoprecipitation analysis revealed a stable complex of GRB2 and 230-kDa BCR/ABL proteins, indicating that the Ras activation pathway is involved in the process of transformation. AR230 expressed another short transcript consisting of a BCRc2/ABL junction, which is associated with a stop signal shortly after the junction. To our knowledge, this is the first cell line expressing a 230-kDa fusion product of BCR/ABL. AR230 will be useful for studying the biological function of divergent BCR/ABL proteins.
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PMID:Establishment and molecular characterization of a novel leukemic cell line with Philadelphia chromosome expressing p230 BCR/ABL fusion protein. 760 40

It has previously been shown that a cluster of HpaII sites with the potential to be methylated exist around exon b3 of the M-bcr region involved in the formation of the Philadelphia chromosome in chronic myeloid leukemia (CML). The degree of hypermethylation of these sites can be directly correlated with the percentage of immature cells, whilst progressive hypomethylation occurs during the maturation of the granulocyte lineage. We have examined samples obtained from CML patients at diagnosis, during chronic phase, and blast crisis to examine the degree of methylation of this region in the non-rearranged BCR gene and the rearranged BCR-ABL gene. A low degree of methylation of the non-rearranged gene, similar to that observed in normal individuals, was observed in diagnosis and chronic phase samples. Increased methylation was observed during blast crisis indicative of the presence of immature cells in the samples. In contrast, a significantly lower degree of methylation was observed in the rearranged BCR-ABL gene at the onset of blast crisis. Division of the samples into those patients who had lost exon b3 during the formation of the BCR/ABL gene and those that had retained exon b3 produced differing patterns of methylation during disease progression. The former group, who also expressed a b2-a2 mRNA, showed an increase in methylation of the non-rearranged BCR gene prior to and during blast crisis, with a inverse decrease in the methylation of the BCR/ABL gene. Those patients who had retained exon b3, and expressed a b3-a2 mRNA, showed no change in the extent of methylation of the BCR/ABL gene but did exhibit an increase in methylation of the BCR gene during blast crisis. The consequence of the differing degree of methylation during disease progression could affect, to some extent, the specificity of protein binding or RNA expression.
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PMID:Methylation of the major breakpoint cluster region (M-bcr) in Philadelphia-positive CML. 768 49

alpha-Interferon (IFN) has been used to induce cytogenetic remission in chronic myeloid leukaemia (CML), but there are few indicators to predict IFN response. The role of the chimaeric BCR/ABL gene in the malignant process is undisputed. There are, however, conflicting views as to whether the breakpoint site within the BCR gene, and the type of mRNA produced determine disease prognosis and progression. The function and clinical significance of the newly discovered ABL/BCR mRNA has not been investigated for a correlation with CML prognosis or response to therapy. We have used a two-step reverse transcriptase polymerase chain reaction (RT-PCR) to detect the transcripts of the chimaeric genes BCR/ABL, ABL/BCR, as well as the normal ABL and BCR genes in 24 CML patients treated with IFN. Because of the variable expression of the four transcripts at presentation, a correlation between gene expression, prognosis and clinical progression was examined. No correlation between prognosis and gene expression was seen. Also, no correlation was found between expression of BCR, ABL or BCR/ABL mRNA and response to treatment with IFN. However, 7/10 ABL/BCR mRNA positive patients achieved a major cytogenetic response to IFN; but of the 13 ABL/BCR mRNA negative patients, only two achieved a major cytogenetic response (P = 0.013). Further studies are required to confirm these findings.
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PMID:Interferon response in chronic myeloid leukaemia correlates with ABL/BCR expression: a preliminary study. 773 52

Leukemias induced with the v-abl or BCR/ABL oncogene undergo a process of tumor progression which suggests that the ABL oncogene is required but not sufficient for full transformation. In order to identify cellular changes that correlate with progression to full transformation in v-abl transformed lymphoblasts Abelson virus (A-MuLV)-infected murine bone marrow was plated over a pre-established stromal feeder layer. Shortly after A-MuLV infection, transformed lymphoblasts were poorly oncogenic, but over time, progressed in a stepwide manner to a more oncogenic state. The transformants first acquired the ability to grow efficiently in agar, but only over the feeder layer. They next progressed to efficient feeder-independent growth in liquid culture, and then to efficient feeder-independent growth in soft agar. Cell lines that reached the advanced stage of feeder-independent agar growth showed increased detection by antiphosphotyrosine Western blot of the GAP-associated p62 phosphoprotein as well as of a 55 kDa phosphoprotein while detection of the P160 v-abl phosphoprotein remained constant throughout all stages of progression. Although the identity of the p55 phosphoprotein and the mechanism by which detection of p55 and p62 phosphoproteins change on the Western blots during tumor progression are unknown, the data demonstrate that these changes strongly correlate with the stage of progression of v-abl-transformed cells and raise the possibility that these changes may play a role in tumor progression in this model.
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PMID:Increased detection of specific tyrosine phosphoproteins correlates with tumor progression of Abelson virus-infected lymphocytes. 784 13

The Philadelphia chromosome (Ph1), present in > or = 95% of chronic myelogenous leukemia (CML) patients, is a well-characterized translocation that results in a unique chimeric gene product (BCR/ABL) with transforming capability. Molecular methods utilizing the polymerase chain reaction (PCR) to detect BCR/ABL mRNA transcripts has been useful for detecting minimal residual disease (MRD) after treatment, as well as for establishing the diagnosis of CML. Amplification-based assays for the BCR/ABL transcript, however, have shown variable reproducibility and sensitivity. This variability may be largely due to technical differences and insufficient controls. In this report, we describe the development of a highly controlled, reproducible, and sensitive PCR assay to detect Ph1 that is well suited to clinical and research applications. A validation study of 82 samples was performed consisting of 25 dilutions of K562 cells (Ph1+) into normal cultured B cells, 26 pre- and post-transplant peripheral blood samples from CML patients, 16 peripheral blood samples for diagnosis of CML, and 15 peripheral blood samples from healthy individuals. RNA isolated from 3 to 5 million leukocytes was reverse transcribed (RT) and amplified by nested primer PCR. The products were characterized using agarose gel electrophoresis. Approximately 1000 Ph1-positive cells admixed with 10(6) normal cells were detectable after one round of amplification. In 60% of assays where one Ph1-positive cell was admixed with 10(6) normal cells, a BCR/ABL product was detectable after nested primer PCR. Specific measures to ensure accurate results in routine testing included (a) assessing RNA integrity and adequate cDNA preparation by detection of the constitutively expressed ABL mRNA, (b) monitoring sensitivity with the addition and detection of K562 RNA mixed with RNA from unknown samples (failure to detect the "spiked" K562 RNA indicates the presence of inhibitors or ribonucleases within the unknown RNA sample), (c) detection of nucleic acid contaminants by using negative controls in every assay, and (d) duplicate analysis of all samples and controls. Internally, this assay was 100% reproducible. Our results verify that nested primer RT-PCR is a fast, sensitive alternative to cytogenetic or Southern blot analysis for monitoring MRD after treatment and for diagnosis of CML. In addition, the highly controlled detection scheme presented here can be used as a general model for the development of other amplification-based detection assays.
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PMID:Development of a sensitive, highly controlled assay for molecular detection of the Philadelphia chromosome in patients with chronic myelogenous leukemia. 785 90

We report cases with a variant BCR/ABL mRNA expression lacking ABL exon a2 sequences. Two of these cases showed major breakpoint cluster region (BCR) exon 3 (b3) and ABL exon 3 (a3) junction (b3/a3), while the other case showed minor BCR exon 1 (e1) and a3 junction (e1/a3). One of the two cases with b3/a3 junction and the case with e1/a3 junction were diagnosed as acute lymphoblastic leukemia, and the remaining case with b3/a3 junction was chronic myeloid leukemia. Two of these cases, however, were found to have a breakpoint in the ABL gene outside of the intron between exons a2 and a3, probably 5' upstream of exon a2, suggesting that the BCR exon was spliced to ABL exon a3. These findings differ from those previously reported, in which the breakpoints in the ABL gene were between exons a2 and a3, and indicate a novel mechanism for the deletion of ABL exon a2 sequences in the formation of a variant BCR/ABL fusion transcript. The significance of the finding that a part of the SH3 region of ABL protein is missing in some Philadelphia chromosome-positive leukemias is discussed in reference to the cases reported previously.
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PMID:Heterogeneity of the breakpoint in the ABL gene in cases with BCR/ABL transcript lacking ABL exon a2. 793 65

Initially, lymphoid cells transformed by v-abl or BCR/ABL oncogenes are poorly oncogenic but progress to full transformation over time. Although expression of the oncogene is necessary to initiate and maintain transformation, other molecular mechanisms are thought to be required for full transformation. To determine whether tumor progression in ABL oncogene-transformed lymphoid cells has a genetic basis, we examined whether progression of the malignant phenotype of transformed clones correlates with particular cytogenetic abnormalities. A modified in vitro bone marrow transformation model was used to obtain clonal Abelson murine leukemia virus-transformed B lymphoid cells that were poorly oncogenic. Multiple subclones were then derived from each clone and maintained over a marrow-derived stromal cell line for several weeks. Over time, clonally related Abelson murine leukemia virus-transformed subclones progressed asynchronously to full transformation. The data show that tumor progression can occur in the absence of detectable cytogenetic changes but, more importantly, that certain cytogenetic abnormalities appear reproducibly in highly malignant subclones. Therefore, three independent subclones showed deletion in a common region of chromosome 13. Other highly malignant cells carried a common breakpoint in the X chromosome, and, finally, two subclones carried an additional chromosome 5. These results are consistent with the hypothesis that ABL oncogenes are sufficient for the initial transformation of cells but that additional genetic events can drive oncogenic progression. These observations further suggest that diverse genetic mechanisms may be able to drive tumor progression in cells transformed with ABL oncogenes.
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PMID:Nonrandom cytogenetic changes accompany malignant progression in clonal lines abelson virus-infected lymphocytes. 799 46

Previous studies designed to identify the Ph chromosome in T lymphocytes from patients with chronic myelogenous leukaemia (CML) were mostly based on small numbers of patients. To examine the possibility that the occasional CML patient might have major penetration of the T-cell compartment by the leukaemic clone, we studied interphase T cells from the blood of 11 CML patients conventionally treated in chronic phase and three in relapse after allogeneic bone marrow transplant (BMT) by fluorescence in situ hybridization using BCR and ABL cosmid probes. Granulocytes from the same patient and cells from the SD-1 CML cell line served as positive controls. Cells with juxtaposition of BCR and ABL signals or with the two signals up to one signal diameter apart were scored as positive. In each CML patient the incidence of 'positive' T cells was much less than in positive controls and similar to that found in negative controls (mean values +/- 1 SD: 7.7 +/- 3.6; 91.2 +/- 3.1, and 5.6 +/- 2.2, respectively). We conclude that none of the patients studied by this technique had any appreciable proportion of BCR/ABL-positive T cells in the circulation.
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PMID:T lymphocytes in chronic myelogenous leukaemia (CML): no evidence of the BCR/ABL fusion gene detected by fluorescence in situ hybridization in 14 patients. 803 12


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