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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The t(15;17) translocation is specifically observed in patients with promyelocytic leukemia (AML3). The chromosomal rearrangement juxtaposes the retinoic acid receptor alpha (RAR alpha) and PML genes, resulting in PML/RAR alpha fusion transcripts. Our previous studies have shown that a polymerase chain reaction (PCR) amplification product could be obtained from the cDNA of the NB4 promyelocytic cell line from which the chimaeric PML/RAR alpha was cloned. We report here that in all 14 AML3 patients tested, reverse transcriptase-PCR (RT-PCR) allows the detection of three specific fusion products. In eight patients, one amplification product was detected corresponding to the previously described abnormal fusion. Five patients displayed a different amplified fragment corresponding to a different fusion point. One other patient always showed a third different-sized product. The different types of fusion transcripts amplified were correlated to the size of the abnormal RAR alpha transcripts detected in these patients by Northern analysis, but did not prove determinant for either the phenotypic features or the retinoic acid responsiveness in AML3 cells in this group of patients. The consistent identification by RT-PCR of the fusion of the PML and RAR alpha genes in AML3 patients suggest that this method will provide a useful tool for the diagnosis and detection of minimal residual disease in these patients.
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PMID:A PML/retinoic acid receptor alpha fusion transcript is constantly detected by RNA-based polymerase chain reaction in acute promyelocytic leukemia. 137 40

Acute promyelocytic leukemia (APL) is a subtype of acute myelogenous leukemia (AML) that is characterized by the presence of a PML/RAR alpha fusion gene resulting from t(15;17). Peripheral stem cell transplantation (PSCT) has been used to treat patients with AML. To assess the presence of minimal residual disease (MRD) and the contamination of leukemic cells in peripheral stem cells (PSCs), we examined six patients with APL who were undergoing PSCT, using reverse transcriptase polymerase chain reaction analysis to detect the mRNA of the PML/RAR alpha fusion gene. The fusion gene was expressed in the bone marrow cells during the early phase of a complete remission and in some of the PSCs. Detection of the fusion gene can be useful in monitoring for leukemic cell contamination of PSCs and for predicting a relapse of APL.
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PMID:Detection of minimal residual disease by reverse transcriptase polymerase chain reaction for the PML/RAR alpha fusion mRNA: a study in patients with acute promyelocytic leukemia following peripheral stem cell transplantation. 753 17

The acute promyelocytic leukemia (APL)-specific t(15;17) chromosome abnormality is characterized at the molecular level by rearrangement of the PML and RAR alpha genes, resulting in fusion PML/RAR alpha mRNA and a chimeric protein. Besides its relevance in the pathogenesis of the disease, this hybrid gene represents a specific tumor marker that is rapidly detectable by reverse transcriptase-polymerase chain reaction (RT-PCR) in the RNA extracted from leukemic blasts. Several studies have highlighted the clinical relevance of PML/RAR alpha detection, which provides a specific diagnosis, prognostic information, and prediction of relapse when monitoring residual disease during the follow-up. In fact, this hybrid gene is detected in 100% of APLs. Rare cases of patients with a morphological diagnosis of FAB M3 AML who lack the specific PML/RAR alpha abnormality have been reported as being unresponsive to differentiation treatment. Finally, all the studies reported so far on PCR monitoring in APL have documented that the identification of small amounts of residual disease at remission strongly predicts impending relapse. Thus, RT-PCR of the hybrid PML/RAR alpha gene is currently performed prospectively as part of cooperative clinical trials aimed at better addressing post-remission treatment in APL.
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PMID:The PML/RAR alpha fusion gene in the diagnosis and monitoring of acute promyelocytic leukemia. 762 53

Acute promyelocytic leukaemia (APL) associated with a t(15;17) translocation generates a PML/RAR alpha chimaeric gene which is transcribed as a fusion PML/RAR alpha mRNA. To clarify the pathophysiologic role of PML/RAR alpha in APL patients, we examined the expression of PML/RAR alpha in haemopoietic colonies in five patients with APL by reverse transcriptase polymerase chain reaction (RT-PCR) analysis. By the two-step RT-PCR method, we demonstrated that PML/RAR alpha positive clones were present in progenitor cells including both CFU-GM and BFU-E in two cases. This result suggests that the translocation of PML/RAR alpha occurred in a pluripotent stem cell in some APL patients. In four patients we detected two amplified cDNA fragments of 780 and 640 bp which presumably arose by alternative splicing of the PML gene. Interestingly, of CFU-GM and BFU-E colonies examined in four patients, there were three different types of colonies: those expressing only the 780 bp fragment, those expressing only the 640 bp fragment, and those expressing both fragments. This suggests that alternative splicing was clonally determined in each colony. We describe a useful RT-PCR technique for the study of gene expression in a limited number of haemopoietic precursor cells.
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PMID:PML/RAR alpha fusion gene is expressed in both granuloid/macrophage and erythroid colonies in acute promyelocytic leukaemia. 813 68

The PML/RAR alpha fusion gene resulting from the t (15;17) translocation is a specific marker for acute promyelocytic leukemia (APL). We examined bone marrow cells by reverse transcriptase-polymerase chain reaction (RT-PCR) to detect residual PML/RAR alpha mRNA-containing cells following treatment with all-trans retinoic acid (ATRA) and cytotoxic chemotherapy in a patient with APL. This RT-PCR assay can detect one leukemic cell in 10(2) normal cells in vitro. We show that PML/RAR alpha mRNA was still detectable despite clinical remission following ATRA treatment, but undetectable following consolidation with chemotherapy. These data show that this technique is useful for the identification of minimal residual disease in patients with APL and that cytotoxic chemotherapy following ATRA therapy is required for the elimination of APL cells.
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PMID:Detection of minimal residual disease in a patient with acute promyelocytic leukemia by RT-PCR: necessity of chemotherapy following ATRA therapy. 814 29

We report a case with typical clinical features of acute promyelocytic leukemia (APL) carrying an atypical chromosomal aberration involving chromosomes 15, 17, and 18. Molecular analysis using Southern blot hybridization and reverse transcriptase-polymerase chain reaction (RT-PCR) proved the creation of the PML/RAR alpha fusion gene in this case. These findings support the notion that this fusion is of crucial importance to leukemogenesis of APL.
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PMID:Detection of the PML/RAR alpha fusion gene in acute promyelocytic leukemia with a complex translocation involving chromosomes 15, 17, and 18. 840 46

The translocation t(15;17)(q24;q21), unique to acute promyelocytic leukemia (APL), gives rise to PML/RAR alpha fusion transcripts detected by the sensitive reverse transcriptase-polymerase chain reaction (PCR) technique. PCR may help in the diagnosis and in monitoring minimal residual disease. Reversion of PCR to negative is obtained by chemotherapy (CT) alone or in combination with all-trans retinoic acid (ATRA). Here we show a serial PCR study of 10 APL cases. Five cases were studied at the time of diagnosis, and all were PCR positive for the rearranged transcripts (three bcr1 type, two bcr3 type). Seven cases in complete remission (CR) after one cycle of induction CT were persistently PCR negative, one case in CR after ATRA rescue was persistently PCR positive (bcr1 type), one patient (bcr3 type) relapsed 15 months after the PCR-negative CR and one patient died early. Seven patients underwent bone marrow transplantation (BMT) (five allogeneic, two autologous). One of them died early after take of the allogeneic BMT, the other six cases studied by serial PCR were persistently negative. At a median follow-up of 31 months (range 9-39), none of these six cases had relapsed. PCR data characterize the CR at the molecular level and evaluate the efficacy of different treatments, including BMT. The data may help to define a standardized schedule for PCR follow-up, and are also potentially useful to establish the time required before judging patients with persistently negative PCR to be cured. BMT as post-induction treatment in first CR is also discussed.
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PMID:PML/RAR alpha transcripts monitored by polymerase chain reaction in acute promyelocytic leukemia during complete remission, relapse and after bone marrow transplantation. 863 28

Acute promyelocytic leukemia (APL) is characterized cytogenetically by the t(15;17)(q22;q11-21) translocation. To compare molecular events among pediatric and adult APL cases, we designed two sets of oligonucleotide primers using published cDNA sequence for PML/RAR alpha fusion transcripts, and undertook reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of 22 US pediatric cases of APL. PML/RAR alpha fusion transcripts were detected in all APL cases, including two cases lacking cytogenetic evidence of t(15;17). Breakpoint usage in PML was determined using a combination of PCR amplification with differing 5' primers, junction-specific probes, and sequence analysis in selected cases. Consistent with previously published data, case analysis demonstrated fusion products resulting from three breakpoint cluster regions (bcr) in PML, and a single breakpoint region in intron 2 of RAR alpha. Transcripts resulting from breakpoints in bcr1 were detected in 59 percent of cases, bcr2 in 27 percent and bcr3 in 14 percent. This distribution is dissimilar to that observed in adults, where bcr2 comprises a lesser and bcr3 a greater portion of cases. These results suggest that the pathogenesis of the t(15;17) in APL may differ among patient sets. RT-PCR with these primer sets is a reliable method for detecting PML/RAR alpha chimeric transcript in t(15; 17)-containing APL.
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PMID:Molecular analysis of the PML/RAR alpha chimeric gene in pediatric acute promyelocytic leukemia. 870 34

We studied the quantitative changes in PML/retinoic acid receptor alpha (PML/RAR alpha) fusion mRNA using the reverse transcriptase-polymerase chain reaction (RT-PCR) and the in vitro differentiation of leukemic cells from eight acute promyelocytic leukemia (APL) patients during treatment with all-trans retinoic acid (ATRA). In three patients, the intensity of the chimeric PML/RAR alpha bands decreased rapidly after the start of ATRA therapy. However, these three patients required variable periods of time to obtain complete remission (CR) (24, 29 and 100 days). In the five other patients, the chimeric bands decreased slowly, and the time until CR also varied (22, 28, 30, 39 and 67 days). As for the in vitro assay, leukemic cells from the three patients who achieved CR in a short period of time (22, 28 and 30 days) showed marked differentiation in response to 1 mumol/L ATRA, and leukemic cells from the four patients with slow or delayed clinical responses to ATRA did not show morphological differentiation in vitro. These findings suggest that the clinical response of APL patients to ATRA is predicted from the results of the in vitro differentiation assay, but not by RT-PCR analysis of the PML/RAR alpha fusion mRNA.
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PMID:Evaluation of semiquantitative reverse transcriptase-polymerase chain reaction assay of PML/retinoic acid receptor alpha mRNA and in vitro differentiation assay as prognostic prediction in acute promyelocytic leukemia treated with all-trans retinoic acid. 881 May 54

We treated two children with acute promyelocytic leukemia (APL) in whom complete remission was successfully induced by oral administration of all-trans retinoic acid (ATRA). We followed these patients with conventional chemotherapy. The first patient has remained in continuous complete remission. However, the other patient relapsed during the maintenance therapy and died of progressive disease in spite of a second treatment with ATRA and chemotherapy. From a clinical point of view, the latter case had a hyperleukocytosis on admission. Also morphologically speaking, this patient had a different M3 variant than the first case. There are two major isoforms of PML/RAR alpha transcripts, so called short and long type transcripts, according to the breakpoints in the PML genes. In the first case the "long type' isoform was detected by reverse transcriptase polymerase chain reaction (RT/PCR) amplification. On the other hand the "short type' isoform was observed in the latter case. Also the second case became PCR positive at relapse, although the detectable isoform was negative during remission. The "short type' isoform may be related to the poor prognosis and RT/PCR analyses may be a powerful to detect early relapse.
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PMID:[Childhood acute promyelocytic leukemia treated with all-trans retinoic acid]. 899 31


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