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)

We observed a patient in whom graft-versus-host disease (GVHD) appeared to induce a positive effect. This 32-year-old male with Philadelphia chromosome-positive acute lymphoblastic leukemia received a bone marrow transplant (BMT) from an HLA-identical sibling donor. We analyzed the bone marrow with the reverse transcriptase-polymerase chain reaction to screen for the minor bcr/abl transcript, which indicates the presence of minimal residual disease (MRD). MRD was present in the pre- and post-transplant phases. There was no evidence of acute GVHD by post-transplant day 45. We abruptly discontinued the immunosuppressive therapy in an attempt to eliminate MRD by inducing an antileukemic reaction during GVHD. GVHD associated with diarrhea and liver dysfunction developed on day 64. On day 105, MRD disappeared and GVHD was treated with prednisolone and cyclosporin. The disappearance of MRD may have been due to the graft-versus-leukemia (GVL) effect mediated by the alloimmune response of donor T lymphocytes. These findings suggest that induction of the GVL effect may be useful for eliminating MRD after BMT in leukemia patients at high risk of recurrence of the disease.
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PMID:Eradication of minimal residual disease during graft-versus-host reaction induced by abrupt discontinuation of immunosuppression following bone marrow transplantation in a patient with Ph1-ALL. 924 45

We report an RNA targeting strategy, which selectively degrades bcr/abl mRNA in chronic myelogenous leukemia (CML) cells. A 2', 5'-tetraadenylate activator (2-5A) of RNase L was chemically linked to oligonucleotide antisense directed against either the fusion site or against the translation start sequence in bcr/abl mRNA. Selective degradation of the targeted RNA sequences was demonstrated in assays with purified RNase L and decreases of p210(bcr/abl) kinase activity levels were obtained in the CML cell line, K562. Furthermore, the 2-5A-antisense chimeras suppressed growth of K562, while having substantially reduced effects on the promyelocytic leukemia cell line, HL60. Findings were extended to primary CML cells isolated from bone marrow of patients. The 2-5A-antisense treatments both suppressed proliferation of the leukemia cells and selectively depleted levels of bcr/abl mRNA without affecting levels of beta-actin mRNA, determined by reverse transcriptase-polymerase chain reaction (RT-PCR). The specificity of this approach was further shown with control oligonucleotides, such as chimeras containing an inactive dimeric form of 2-5A, antisense lacking 2-5A, or chimeras with altered sequences including several mismatched nucleotides. The control oligonucleotides had either reduced or no effect on CML cell growth and bcr/abl mRNA levels. These findings show that CML cell growth can be selectively suppressed by targeting bcr/abl mRNA with 2-5A-antisense for decay by RNase L and suggest that these compounds should be further explored for their potential as ex vivo purging agents of autologous hematopoietic stem cell transplants from CML patients.
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PMID:2',5'-Oligoadenylate-antisense chimeras cause RNase L to selectively degrade bcr/abl mRNA in chronic myelogenous leukemia cells. 983 40

Quantifying bcr/abl fusion transcripts in chronic myelogenous leukemia is thought to serve as a powerful parameter for monitoring the kinetic nature of this clonal disease in vivo and in vitro. Recently, we demonstrated the technical advantages as well as the clinical relevance of quantitating bcr/abl fusion mRNA using the 5-nuclease assay and a real-time fluorescence reverse transcriptase-PCR (RT-PCR) detection system (ABI PRISM 7700 SDS). Meanwhile, another technique was introduced (LightCycler technology) that may be used for the same purpose. To investigate whether this method may be an appropriate alternative to the described procedure, we have established bcr/abl LightCycler RT-PCR for major and minor bcr/abl fusion transcripts. We found that, with only minor modifications, TaqMan RT-PCR and fluorescent probe design can be used to obtain comparable results in the LightCycler system. The developed method could quantitate as little as 10 bcr/abl copies per 100 ng cDNA and was as safe and reproducible as the previously described technique. Because reaction efficiency was identical within different bcr/abl major fusions, one single RT-PCR could be established that simultaneously detects b2a3, b2a2, b3a2, and b3a3 fusion RNA with equal specificity and sensitivity. Compared to results generated by the ABI PRISM 7700 SDS, absolute amounts of bcr/abl did not differ significantly, and there was a linear correlation between the respective values. We conclude that TaqMan chemistry can be used in the LightCycler and that both real-time fluorescence PCR detection systems equally fulfill the criteria for the safe and reliable quantitation of bcr/abl fusion RNA in clinical samples. This may be of help for further standardization of quantitative bcr/abl RT-PCR, which, again, is necessary for the comparison of results generated by different investigators.
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PMID:LightCycler technology for the quantitation of bcr/abl fusion transcripts. 1039 61

Chronic myelogenous leukemia (CML) is characterized by the Philadelphia (Ph) chromosome and bcr/abl gene rearrangement which occurs in pluripotent hematopoietic progenitor cells expressing the c-kit receptor tyrosine kinase (KIT). To elucidate the biological properties of KIT in CML leukemogenesis, we performed analysis of alterations of the c-kit gene and functional analysis of altered KIT proteins. Gene alterations in the c-kit juxtamembrane domain of 80 CML cases were analyzed by reverse transcriptase and polymerase chain reaction-single strand conformation polymorphism (RT-PCR-SSCP). One case had an abnormality at codon 564 (AAT --> AAG, Asn --> Lys), and six cases had the same base abnormality at codon 541 (ATG --> CTG, Met --> Leu) in the juxtamembrane domain. Because the change from Met to Leu at codon 541 was a conservative one which was also observed in the normal population and normal tissues of CML patients, it probably represents a polymorphic variation. Although samples of hair roots and leukemic cells from the chronic phase of one CML patient showed no abnormality, an abnormality at codon 541 (ATG --> CTG, Met --> Leu) was found only at blastic crisis (BC) of this case. In the case with the abnormality at codon 564, the mutation was detected only in a sample of leukemic cells collected at BC. To examine the biological consequence and biological significance of these abnormalities, murine KIT(L540) and KIT(K563) expression vectors were introduced into interleukin-3 (IL-3)-dependent murine Ba/F3 cells to study their state of tyrosine phosphorylation and their growth rate. Ba/F3 cells expressing KIT(WT), KIT(L540) and KIT(K563) showed dose-dependent tyrosine phosphorylation after treatment with increasing concentrations of recombinant mouse stem cell factor (rmSCF). The cells expressing KIT(L540) and KIT(K563) were found to have greater tyrosine phosphorylation than cells expressing KIT(WT) at 0.1 and 1.0 ng/ml of rmSCF. The Ba/F3 cells expressing KIT(K563) proliferated in response to 0.1 and 1.0 ng/ml of rmSCF as well as IL-3. The Ba/F3 cells expressing KIT(L540)showed a relatively higher proliferative response to 0.1 ng/ml of rmSCF than the response of cells expressing KIT(WT). These mutations and in vitro functional analyses raise the possibility that the KIT abnormalities influence the white blood cell counts (P < 0.05) and survival (P < 0.04) of CML patients.
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PMID:Abnormality of c-kit oncoprotein in certain patients with chronic myelogenous leukemia--potential clinical significance. 1630 17

The t(9;22) (q34;q11) between abl and bcr genes plays a pivotal role in the diagnosis and pathogenesis of chronic myelogenous leukemia(CML). To explore the bcr/abl fusion mRNA expression on hematopoietic precursors, reverse transcriptase-polymerase chain reaction(RT-PCR) was applied to detect bcr/abl mRNA expression on bone marrow cell colonies. Meanwhile, bcr/abl mRNA expressions on 14- or 28-day colonies using HPP-CFC and CFU-GM semisolid agar culture assay were also determined in 4 cases of confirmed Ph-positive CML by karyotyping analysis. The results showed that the bcr/abl mRNA expressions on 14-day colonies and some 14- or 28-day colonies detected singly were positive at presentation by RT-PCR, in agreement with results by karyotype analysis. Thus, a sensitive and powerful technique was offered for studying gene expression on hematopoietic precursors, diagnosis and therapeutic monitoring of CML. Furthermore, this can be used as an ideal method for revealing molecular mechanisms of pathogenesis of CML and screening anti-CML drugs.
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PMID:[Detection of bcr/abl gene expression on bone marrow cell colonies in chronic myelogenous leukemia by reverse transcriptase-polymerase chain reaction]. 1208 Jun 71

In order to investigate the safety and efficacy of stem cell mobilization in chronic myeloid leukemia patients under imatinib therapy we treated 10 such patients with granulocyte colony-stimulating factor. We observed that none of the patients developed progressive disease under this treatment. Instead, sufficient CD34+ apheresis could be performed in 7 patients and, as assessed by nested reverse transcriptase polymerase chain reaction (RT-PCR), bcr/abl-negative stem cell products could be generated in 3 patients. Interestingly, in 3 other patients with bcr/abl-positivity in 1st round RT-PCR of peripheral leukocytes, bcr/abl transcripts in stem cell products could only be detected by nested RT-PCR.
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PMID:Safety and efficacy of stem cell mobilization under imatinib therapy. 1455 23

This report describes a patient with Philadelphia chromosome-negative (Ph-) but bcr/abl fusion gene-positive chronic myeloid leukemia (CML) and a molecular analysis of the mechanisms behind the Ph status. Spectral karyotyping-fluorescent in situ hybridization (SKY-FISH) analysis showed no abnormal translocation; however, a bcr/abl fusion gene was detected by reverse transcriptase-polymerase chain reaction analysis. FISH analysis showed that signals from the 9q and 22q subtelomere probes were detected on the der(9) and der(22) chromosomes, respectively. On the other hand, FISH analysis of the abl and bcr genes with dual fusion probes, which can detect the bcr/abl fusion gene on both the der(9) and der(22) chromosomes, showed the signal for bcr/abl fusion on the der(22) chromosome but not on the der(9) chromosome. These results indicate that insertion of the abl gene into the bcr region on the der(22) chromosome or retranslocation between the der(9) chromosome and the der(22) chromosome may have caused the Ph CML in this case.
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PMID:Fluorescent in situ hybridization analysis of Philadelphia chromosome-negative chronic myeloid leukemia with the bcr/abl fusion gene. 1548 44

This study was aimed to investigate the effects and the mechanism of mangiferin on chronic myeloid leukemia cell lines K562 cells in vitro. The antiproliferation effects of mangiferin on K562 leukemia cells were tested by tetrazolium salt (MTT) method; the apoptosis induced by mangiferin on K562 cell line was explored by means of cell morphology, DNA gel electrophoresis and flow cytometry. The changes in bcr/abl gene expression was detected by using reverse transcriptase (RT)-PCR. The results showed that five different concentrations of mangiferin (25 - 200 micromol/L) dose-dependently and time-dependently inhibited the proliferation of K562 cells, and induced apoptosis in K562 cell line. RT-PCR revealed that bcr/abl gene expression was down-regulated when K562 cells had been treated with different concentrations of mangiferin. In conclusion, mangiferin remarkably inhibits the proliferation of K562 leukemia cells in vitro, and induces apoptosis in K562 cell line probably through down-regulation of bcr/abl gene expression.
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PMID:[CML cell line K562 cell apoptosis induced by mangiferin]. 1549 16

This study was purposed to investigate the sensitivity and specificity of conventional cytogenetics (CC), nested-reverse transcriptase polymerase chain reaction (nested-RT-PCR) and dual-color/dual-fusion fluorescence in situ hybridization (D-FISH) technique in monitoring the tumor load of chronic myeloid leukemia (CML) during treatment with transplantation. CC, nested-RT-PCR and interphase D-FISH were simultaneously carried out to detect the tumor load of 7 CML patients during treatment with non-myeloablative allogeneic stem cell transplantation (allo-NSCT). 40 specimens from 7 CML patients before and after allo-NSCT were analyzed. The results showed that 29 specimens were Ph (+) with different positive ratio and 3 specimens with lower cells were not analyzed by CC. 36 specimens were bcr/abl mRNA (+) by RT-PCR. 4 specimens from case 1 at 12, 18, 26 and 38 months after allo-NSCT were Ph (-) and bcr/abl mRNA (-), 4 Ph (-) bcr/abl (+) specimens containing 2 from case 1 at 9 and 10 months after allo-NSCT, 1 from case 2 at 15 months after allo-NSCT, 1 from case 3 at 12 months after allo-NSCT showed 5.4%, 0%, 16.5% and 1.5% bcr/abl (+) cells by FISH. 3 specimens with lower cells containing 2 from case 5 at 20 and 60 days after allo-NSCT and 1 from case 7 at 40 days after allo-NSCT were analyzed by FISH and showed 55.0%, 27.5% and 73.5% bcr/abl (+) cells. The Ph (-) bcr/abl (-) specimen from case 1 at 12 months post-allo-NSCT showed 0% bcr/abl (+) cells by FISH. It is concluded that CC can be used as a basic tool to monitor the change of tumor load in CML during treatment. When specimen with lower cells can not be analyzed by CC in early period after allo-NSCT, or result of CC can not evaluate precisely dynamic change of tumor load and when tumor load in treated patient are lower to Ph (-) by CC while bcr/abl mRNA (+) by RT-PCR, FISH must be used to detect precisely tumor load and monitor dynamic change of it. More sensitive RT-PCR is used to monitor tumor load when it is lower to bcr/abl (-) by FISH during treatment.
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PMID:[Detection of tumor load in chronic myeloid leukemia during treatment with transplantation by conventional cytogenetics, nested-RT-PCR and FISH]. 1749 23


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