Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eight cases with Ph1 positive acute leukemia (7 of acute lymphocytic leukemia: ALL, and one of acute myelocytic leukemia: AML) were studied molecular biologically to identify location of breakpoints on BCR gene in each patient. Six of the 8 patients (5 of ALL and 1 of AML) had rearrangements at bcr (M-BCR) region. Their locations of the breakpoint in M-BCR were similar to those of 59 chronic myelocytic leukemia patients. One of the remaining two patients had gene rearrangements at m-BCR-1 region in BCR intron 1, and the last patient did not have gene rearrangements at any site of m-BCR-1 and IgL C lambda region. Two cases had gene deletion at either 3' or 5' side of the bcr. A patient with bcr rearrangement was also analyzed by PCR method with reverse transcriptase (RT-PCR) and had simultaneous expressions of bcr3-abl and bcr2-abl chimeric mRNAs. These results indicate that Ph1 positive acute leukemia have heterogeneous characteristics in terms of the molecular biology. The molecular analysis will help for classifying the leukemic types and for elucidating the pathogenesis in Ph1 positive acute leukemia.
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PMID:[Analysis of breakpoints on BCR gene in acute leukemia patients with Ph1 chromosome]. 154 9

Chronic myelogenous leukemia (CML) is characterized cytogenetically by the presence of the Philadelphia chromosome, which is the result of a reciprocal translocation between chromosomes 9 and 22. Analysis of the rearranged chromosome 22 have demonstrated that the DNA breakpoints fall within a 5.8-kilobase (kb) region termed M-bcr. In Ph1-acute lymphocytic leukemia, approximately half of the patients have a breakpoint within M-bcr, whereas the remaining half have the break within the first intron of the BCR gene (m-bcr). We have investigated five cases with CML in the blastic phase to search the molecular mechanism of blastic crisis in CML. Using a method of reverse transcriptase-polymerase chain reaction (RT-PCR), we have identified both types of breakpoints in samples of the three cases, suggesting the existence of M-bcr/ABL and m-bcr/ABL chimeric mRNAs in the RNA samples derived from blasts of the three cases. We have further analysed for alterations in the p53 gene in those cases. The p53 gene is now considered to be a tumor suppressor gene and its mutations play a role in the development of many human malignancies. We have attempted to determine whether the p53 gene is involved in the mechanism of blastic crisis in CML. Using the methods of RT-PCR and single stand-conformational polymorphism (SSCP), we have detected expression of only a mutated p53 allele in a case with CML blastic crisis, indicating that inactivation of the p53 gene in both alleles may contribute to the blastic crisis in this case. Accumulation of molecular analysis in more cases will clarify the mechanism of blastic crisis in CML.
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PMID:[Analysis of Ph1-positive leukemia by PCR]. 206 73

Transformation of hematopoietic cells by the p210bcr/abl tyrosine kinase appears to require the expression of a functional MYC protein, suggesting that simultaneous targeting of BCR-ABL and c-myc might be a rational strategy for attempting treatment of Phil-adelphia leukemia. To test this hypothesis, severe combined immunodeficiency mice injected with Philadelphia leukemic cells were treated systemically with equal doses of bcr-abl or c-myc antisense oligodeoxynucleotides (ODNs) or with both ODNs in combination. Compared with the mice treated with individual agents, the disease process was much slower in the group treated with both ODNs, as revealed by flow cytometry, clonogenic assay, and reverse transcriptase-polymerase chain reaction analysis to detect leukemic cells in mouse tissue cell suspensions, and by enumeration of liver metastases. The retardation of the disease process was positively correlated with a markedly increased survival of leukemic mice treated with both ODNs. These data demonstrate the therapeutic potential of targeting multiple cooperating oncogenes.
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PMID:Leukemia treatment in severe combined immunodeficiency mice by antisense oligodeoxynucleotides targeting cooperating oncogenes. 750 9

The major bcr-abl fusion gene is presently seen as the hallmark of chronic myeloid leukemia (CML) and presumably as the cause of its development. Accordingly, long-term disappearance of bcr-abl after intensive therapy is considered to be a probable cure of CML. The nested reverse transcriptase-polymerase chain reaction (RT-PCR) provides a powerful tool for minimal residual CML detection. The RT-PCR was optimized by (1) increasing the amount of total RNA involved in the reverse transcription reaction to correspond to total RNA extracted from 10(8) cells, (2) using a specific abl primer in this reverse reaction, and (3) reamplifying 10% of the RT-PCR product in nested amplification. This optimized RT-PCR permitted us to detect up to 1 copy of RNA bcr-abl synthesised in vitro, mixed with yeast RNA in an equivalent quantity to 10(8) white blood cells (WBCs). Using this highly sensitive RT-PCR during the follow-up of CML patients, a signal was unexpectedly found in healthy controls. Therefore, a systematic study of the possible expression of bcr-abl RNA in the WBCs of healthy adults and children and in umbilical cord blood was undertaken. It showed the presence of bcr-abl transcript in the blood of 22 of 73 healthy adults and in the blood of 1 of 22 children but not in 22 samples of umbilical cord blood.
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PMID:Detection of major bcr-abl gene expression at a very low level in blood cells of some healthy individuals. 757 6

hLH-2, a transcription factor that contains double cysteine rich regions (LIM motifs) and a homeobox (Hox) DNA-binding domain shows aberrant high expression in all cases of chronic myelogenous leukemia (CML). This gene has been mapped to the chromosome 9q33-34.1, the same region as the reciprocal translocation that creates the breakpoint cluster region (BCR)-ABL chimera of the Philadelphia chromosome (Ph'). To investigate the possible involvement between the BCR-ABL fusion gene and hLH-2 in the pathogenesis of CML, an hLH-2-negative CML cell line, JK-1 that carries double Ph' chromosomes, was examined. Like other CML cells, high BCR-ABL fusion mRNA levels are expressed, but no transcript of hLH-2 was detected in JK-1 cells as determined by reverse transcriptase-polymerase chain reaction (RT-PCR). Compared with the CML cell line, K-562, an additional rearrangement of the BCR gene was observed in JK-1 as determined by Southern blot hybridization; however, the hLH-2 gene was normal. These findings raise interesting questions about the possible roles of either the abnormal BCR gene or other genetic events such as the complex chromosomal abnormalities that result in hLH-2 being turned off in JK-1 cells.
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PMID:A structurally abnormal breakpoint cluster region gene in a transcription factor, hLH-2-negative human leukemia cell line. 760 May 33

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

More than 95% of the patients with chronic myelogenous leukemia (CML) carry translocations between protooncogene abl of chromosome 9 and bcr gene of chromosome 22, resulting in the Philadelphia chromosome (Ph1). After allogeneic bone marrow transplantation (BMT) it is important to detect possible residual malignant cells in CML patients. A new sensitive hybridization method combined with polymerase chain reaction (PCR), based on the detection of the europium (Eu3+) label by time-resolved fluorescence, was applied for the detection of Ph1 chromosome. Total RNA from 10(6) peripheral blood leukocytes was isolated by the acid guanidinium thiocyanate-phenol-chloroform extraction. After cDNA synthesis by reverse transcriptase, the PCR amplification (30 cycles) was carried out. In the detection phase two oligonucleotide probes were used in the hybridization reaction, one biotinylated (bcr gene, exon 2) and one (abl gene) labeled with Eu3+. The hybrids were collected in a streptavidin-coated microtitration well and the bound Eu3+ was measured in a time-resolved fluorometer. To assess the sensitivity of the method, different numbers of CML cell line K562 cells were mixed with 10(5) apparently normal human leukocytes. Five K562 cells/10(5) leukocytes could be detected. Six patients with CML confirmed by clinical and cytogenetic criteria were studied. Three of the patients underwent an allogeneic BTM 6-18 months before the investigation and all of them were Ph1-negative. The other three patients who were nontransplanted were positive as expected.
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PMID:Detection of Philadelphia chromosome using PCR and europium-labeled DNA probes. 786 15

We sequentially analyzed the immunoglobulin heavy chain variable (IgH V) region gene of leukemia cells obtained from a chronic myeloid leukemia (CML) patient who had three episodes of B-lymphoid crisis after bone marrow transplantation. Southern blot analysis using the JH probe showed different rearranged bands at each crisis, although the same rearranged bands of the BCR gene were observed. We amplified and sequenced the IgH V region gene of the leukemia cells by reverse transcriptase polymerase chain reaction (RT-PCR) using the primers corresponding to the consensus 5'VH and mu constant regions. The dominant leukemia clone at each crisis had a unique VH-D-JH rearrangement; VH4A (V79)-DLR2-J5 (clone-1), VH4B (DP70)-DK4-J6 (clone-2) and VH4A (V79)-DN4-J6 (clone-3) at the first, second and third crises, respectively. Further analysis by PCR amplification using the consensus 5'VH and clone-specific primers revealed that clone-1 underwent VH4-->VH3 replacement at the second crisis, and that clone-3 was already in existence at the first crisis. Moreover, the DN4-J6 joining clone, in which the sequence was the same as that of clone-3, was identified at the first and third crises by PCR amplification using primers corresponding to the region upstream of the DN4 segment and DN4-J6 boundary of clone-3. These observations suggest that multiple clones were generated from the progenitor cells of blast crisis, which were transformed at a very early stage of B-lymphocyte ontogeny, by continuing rearrangement mechanisms of the IgH genes, and that the dominant clone at each crisis was undergoing change.
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PMID:Continuing immunoglobulin heavy chain gene rearrangements in chronic myeloid leukemia with recurrent B-lymphoid blast crises after bone marrow transplantation. 786 62

With the recent advances in molecular technology, diagnostic procedures of the diseases at a DNA level have been introduced in hematological fields. The diagnostic methods used are Southern blotting to detect gene rearrangements, Northern blotting to find gene expressions, RT-PCR (reverse transcriptase-polymerase chain reaction) to identify transcribed fusion messages, and PCR-SSCR (single strand conformation polymorphism) to detect mutated genes. Rearrangements within major Bcr (breakpoint cluster region) were observed in almost all cases in chronic myelogenous leukemia, and breakpoint were found within minor Bcr in Philadelphia-positive leukemia. The rearrangements within the second intron of the retinoic acid receptor-alpha and sixth intron (bcr 1), third intron (bcr 3) and sixth exon (bcr 2) of the PML gene were detected in all cases with acute promyelocytic leukemia. In malignant lymphoma, the rearrangements of immunoglobulin and T-cell receptor genes, and new genes such as Bcl-1, Bcl-2, Bcl-5, Tal-1, and Tal-2 were also reported and rearrangements of the Bcl-5 gene were found in this study using Bcl-5 specific probe which we have cloned. Point mutations and deletions of the genes involved in the coagulation and fibrinolysis system have been reported. One base insertion resulting in elongation of carboxy terminal region and one amino acid deletion in alpha 2-plasmin inhibitor gene were found in two cases of its deficiency. Further study revealed that mutated proteins were retained in the endoplasmic reticulum in the cells. With the development of the PCR method, identification of gene mutation is gradually carried out as a routine work.
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PMID:[Molecular study of hematological diseases]. 791 42

A new Ph1-positive acute lymphoblastic leukemia cell line, designated as ALL/MIK, has been developed from a patient with Ph1-positive acute leukemia. The ALL/MIK cells showed an immunophenotype of common ALL with rearranged JH and Jk genes. The ALL/MIK cells showed no M-bcr rearrangement using Southern blot analysis with either 3' or 5' M-bcr probes, but had the bcr gene rearrangement on bcr-2 within the first intron of the bcr gene. Consistent with this result, the reverse transcriptase-dependent polymerase chain reaction (RT-PCR) assay revealed that the ALL/MIK cells contained the transcript derived fusion of the first exon of bcr gene and the second exon of abl gene. Although the ALL/MIK cells were defined as early pre-B cells by immunophenotypical and genotypical analyses, they were capable of differentiating into monocytoid lineage by when cultured with TPA. Furthermore, another Ph1-positive ALL cell line, (TOM-1), was investigated for its ability to differentiate to monocytoid lineage. TOM-1 was also induced to monocytoid lineage by TPA. Thus, the present study suggested that the leukemic transformation in some Ph1-positive ALL may occur at the level of multipotential hematopoietic cells capable of differentiating towards lymphoid and myelo-monocytoid lineage.
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PMID:Establishment and characterization of a new Ph1-positive ALL cell line (ALL/MIK) presenting bcr gene rearrangement on bcr-2 and ALL-type bcr/abl transcript: suggestion of in vitro differentiation to monocytoid lineage. 816 60


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