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 WT1 gene encoding a zinc finger DNA-binding protein was identified as a tumor suppressor gene being responsible for Wilms' tumor. Recently, aberrant expression of WT1 gene and an inverse correlation between its expression levels and prognosis have been demonstrated in acute myeloid leukemia (AML), suggesting it is a novel tumor marker for leukemic blast cells. To explore whether the WT1 may be used as a marker for detection of minimal residual disease (MRD) in acute leukemia, we examined the sensitivity of the nested reverse transcriptase-polymerase chain reaction (RT-PCR) by using WT1 gene primers in comparison with tumor-specific marker genes, such as PML/RARalpha gene in NB4 cells or bcr-abl gene in K562 cells. In all samples, the integrity of RNA was confirmed by amplification of the c-abl gene as an internal control. The limits in amount of leukemic cells detected by two-step RT-PCR with primers for WT1 or tumor specific fusion gene were 10(-4) and 10(-5) in NB4 cells and 10(-3) to 10(-4) and higher than 10(-6) for K562 cells, respectively. None was WT1 positive in peripheral blood mononuclear cells (MNC) from 29 blood donors, while bone marrow MNCs from eight of 21 cases (38.1%) of nonmalignant patient WT1 gene expression were found. Our results suggested that monitoring of WT1 expression makes it possible to rapidly assess the effectiveness of treatment and follow up MRD in AML cases regardless of the presence or absence of tumor-specific markers.
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PMID:[Expression of the Wilms' Tumor Gene WT1 and Detection of Minimal Residual Disease in Acute Leukemia] 1257 85

Acute promyelocytic leukaemia (APL) is characterized by a unique genetic marker in virtually 100% of cases, i.e. the PML/RARalpha fusion gene which is readily amplified by the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Several international groups reported the prognostic significance of minimal residual disease (MRD) assessment in APL, indicating that sequential PCR analysis should be used as a guide to therapy. In fact, such evaluation offers the possibility of identifying, after front-line treatment, either patients requiring additional therapy or patients at low risk who are presumably cured and who may be spared unnecessary toxicity. In this view, the terms molecular remission and molecular relapse are now widely employed to define a more advanced therapeutic objective and a condition necessitating anticipated salvage, respectively. The introduction of quantitative PCR through automated technologies is likely to further improve standardization of the method and comparison of results obtained in the context of large clinical trials.
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PMID:The importance of molecular monitoring in acute promyelocytic leukaemia. 1293 66

In all, 17 consecutive patients in hematological complete remission (HCR) of acute promyelocytic leukemia (APL) received allogeneic stem cell transplantation (SCT) from an HLA-identical sibling and were monitored by reverse transcriptase polymerase chain reaction of PML/RARalpha prior and after transplant. Median age was 31 years (range 3-50 years). At 10 years, the actuarial probabilities of nonrelapse mortality, relapse and disease-free survival were 32% (95% CI: 8-56%), 33% (95% CI: 6-60%) and 46% (95% CI: 22-70%). Six patients tested PCR +ve (1st HCR n=2; 2nd HCR n=3; 3rd HCR n=1) and 11 PCR -ve (2nd HCR n=11) pre-SCT. Of the six patients PCR +ve, two showed early persistence of PCR positivity and converted to sustained PCR negativity after CSA withdrawal (one died of secondary tumor in molecular remission and one is alive in relapse), while four converted to PCR -ve rapidly (one died of the underlying disease and three are in molecular remission). Of the 11 patients PCR -ve pre-SCT, six died (four of transplant-related mortality, one of relapse and one after heart transplantation) and five are alive, four in molecular remission and one is in relapse. Allogeneic SCT seems a valid option for advanced APL, particularly for the poor prognostic group of patients with pre-SCT molecularly persistent disease.
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PMID:Allogeneic stem cell transplantation for advanced acute promyelocytic leukemia: results in patients treated in second molecular remission or with molecularly persistent disease. 1451 40

Detection of the PML/RARalpha fusion gene by RT-PCR in acute promyelocytic leukemia (APL) blasts is not only critical to commence promptly the specific therapy with all-trans retinoic acid (ATRA) or arsenic trioxide (As(2)O(3)), but also essential for the definition of PML breakpoint type and subsequent monitoring of minimal residual disease (MRD). The current PML/RARalpha amplification techniques with conventional nested PCR are laborious and time consuming, which fails to meet the requirements for rapid diagnosis of APL in clinical practice. Therefore, an easily handled RT-PCR methodology for the rapid and accurate amplification of PML/RARalpha fusion transcripts is needed. A modified one round RT-PCR protocol was described with a few variations which includes rapid extraction of high quality cellular total RNA, cDNA synthesis with random hexamer and M-MLV reverse transcriptase, optimal concentrations of MgCl(2) (1 mmol/L), PCR primers (0.4 micro mol/L) and Taq polymerase (0.01 U/ micro l), hot-start procedure, and concomitant amplification of PML/RARalpha fusion gene and RARalpha internal control under the identical thermocycle parameters. The results in 40 patients with newly diagnosed APL showed that the improved RT-PCR protocol allowed the rapid detection of PML/RARalpha fusion gene and the accurate discrimination of its transcript types, and simultaneous amplification of RARalpha internal control under the identical program in less than 6 hours. There were no false positive or negative results found with the assay. In conclusion, the assay reported here is proved to be a simple, easily handled, and highly specific procedure for the diagnosis of APL cases, particularly those requiring such urgent therapeutic intervention as ATRA or As(2)O(3) and meriting its further application in APL management.
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PMID:[Improved RT-PCR for detection of PML/RARalpha fusion gene in rapid diagnosis of acute promyelocytic leukemia]. 1470 40

We studied the immunophenotype of 100 cases of acute promyelocytic leukemia (APL) with cytogenetic evidence of t(15;17)(q22;q21), 72 hypergranular (M3) and 28 microgranular (M3v), and correlated the results with molecular and clinical features. Most neoplasms (75/100 [75%]) had a typical immunophenotype: CD13+CD33+CD34-HLA-DR-. CD64, CD2, CD34, and HLA-DR were expressed in 27% (24/88), 23% (22/94), 21% (21/100), and 9% (9/98), respectively. CD34 expression was restricted to M3v; HLA-DR and CD2 were expressed more often in M3v than in M3 (P < .001). PML-RARalpha fusion transcripts were detected by reverse transcriptase-polymerase chain reaction in all 70 patients assessed. The short form of PML-RARalpha transcripts was found more frequently in M3v (P < .002) and CD2+ APL (P < .0001) than in M3 and CD2- APL, respectively. The median follow-up was 128 weeks. CD2+ APL was associated significantly with leukocytosis (P = .004), shorter complete remission duration (P = .03), and a trend toward shorter overall survival (P = .07) than CD2- APL. Overall survival for M3v vs M3 (P = .68) and short vs long transcripts (P = .21) was not significantly different. Immunophenotyping is useful for predicting the biologic and clinical behavior of APL.
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PMID:Expression of CD2 in acute promyelocytic leukemia correlates with short form of PML-RARalpha transcripts and poorer prognosis. 1502 45

The anti-CD33 antibody calicheamicinconjugate gemtuzumab ozogamicin (GO) was used to treat 16 patients with acute promyelocytic leukemia (APL) who had relapsed at the molecular level. Of these patients, 8 were experiencing a first, 5 a second, 2 a third, and 1 a fourth relapse. GO was administered at 6 mg/m2 for 2 doses, and patients achieving a new molecular remission (MR) (ie, negativity of the reverse transcriptase-polymerase chain reaction [RT-PCR] test for PML/RARalpha) received a third dose. MR was obtained in 9 (91%) of 11 patients tested after 2 doses and in 13 (100%) of 13 patients tested after the third dose. Of the 3 remaining patients, 1 achieved MR after one GO administration and received no further therapy owing to hepatic toxicity, and 2 showed disease progression during treatment. Quantitative RT-PCR studies showed that responding patients experienced a dramatic decline (at least 2 logs) of the PML/RARalpha transcript after the first GO dose. Of 14 responders, 7 remained in sustained MR for a median of 15 months (range, 7-31 months) while 7 experienced relapse at 3 to 15 months. GO was administered again in 2 patients with relapse, and both obtained a new MR. These data indicate that GO is highly effective as a single treatment for patients with molecularly relapsed APL including those with very advanced disease.
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PMID:Gemtuzumab ozogamicin (Mylotarg) as a single agent for molecularly relapsed acute promyelocytic leukemia. 1518 30

To explore the value of detection of PML/RARalpha gene rearrangement on bone marrow smears (BMS) by dual-color fluorescence in situ hybridization (D-FISH) for the diagnosis of acute promyelocytic leukemia (APL), the locus-specific probes for PML and RARalpha genes labeled directly and respectively by Spectrum Green and Spectrum Orange and the D-FISH technique were used to detect the PML/RARalpha gene rearrangement on BMS in 27 suspected APL patients. The results were compared with that of conventional cytogentics (CCG) and reverse transcriptase polymerase chain reaction (RT-PCR). The results showed that out of 18 newly diagnosed patients 14 were found having t(15;17) translocation by CCG and PML/RARalpha gene rearrangement were confirmed by BMS-D-FISH and RT-PCR. Thus, their APL diagnosis was determined; out of 4 patients in whom t(15;17) translocation was not detected by CCG, one had positive BMS-D-FISH and RT-PCR results, thus, this case was considered as having a cryptic t(15;17) translocation, three had negative BMS-D-FISH and RT-PCR results, thus, they were diagnosed as having acute myeloid leukemia rather than APL. In 9 cases with remission, one case with partial remission was found having t(15;17) translocation by CCG, and he had positive BMS-D-FISH and RT-PCR results, the other 8 patients (6 cases with normal karyotype and 2 cases without CCG examination) displayed different BMS-D-FISH and RT-PCR results: negative in 6 cases, but positive in 2 cases. The 2 cases were believed that they survived with minimal residual disease (MRD). It is concluded that BMS-D-FISH is a sensitive and reliable method for the detection of PML/RARalpha rearrangement. It is helpful for diagnosing APL and monitoring its MRD, and especially fit to those patients presenting a cryptic translocation or with failed cytogenetics, lacking suitable material for RT-PCR, as well as needing retrospective study.
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PMID:[Detection of PML/RARalpha gene rearrangement in suspected acute promyelocytic leukemia patients using dual-color fluorescence in situ hybridization on bone marrow smears]. 1563 55

We describe a patient with acute promyelocytic leukemia (APL) and the karyotype 46,XX,i(17)(q10) with PML-RARA fusion gene detected by fluorescence in situ hybridization (FISH) and nested reverse transcriptase-polymerase chain reaction (RT-PCR). FISH using dual-color translocation probes for PML (promyelocytic leukemia) and RARA (retinoic acid receptor-alpha) showed fusion signal for PML-RARA on both arms of i(17q). The patient attained complete remission (CR) with all-trans retinoic acid treatment and became PML-RARA negative. One year later, while PML-RARA negative on FISH and RT-PCR, the patient presented with thrombocytopenia. Bone marrow examination suggested an acute monoblastic leukemia (AML-M5a) including the karyotype 46,XX,t(8;16) (p11.2;p13.3),inv(11)(p15q22 approximately q23)[11]/47,idem,+i(8)(q10)[9]. She is currently in CR. The occurrence of therapy related acute leukemia after successful therapy for APL is an emerging problem.
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PMID:Acute promyelocytic leukemia with PML-RARA fusion on i(17q) and therapy-related acute myeloid leukemia. 1589 84

Recently, arsenic trioxide (ATO) has been proved to induce complete remission (CR) at a high rate in patients with acute promyelocytic leukemia (APL). We prospectively investigated the safety and efficacy of ATO therapy in patients with relapsed and refractory APL and examined the duration of CR and the postremission therapies. Initially, 0.15 mg/kg ATO was administered until bone marrow remission to a maximum of 60 days. After the patient achieved CR, 1 additional ATO course at the same dosage was administered for 25 days. Of 34 patients, 31 (91%) achieved CR. PML-RAR3 messenger RNA was not detected in the bone marrow of 18 (72%) of the 25 patients evaluated by reverse transcriptase-polymerase chain reaction analysis. At a median follow-up of 30 months, the estimated 2-year overall survival rate was 56%, and the estimated 2-year event-free survival rate was 17%. During the ATO therapy, QTc prolongation was observed in most cases. Fifteen patients developed ventricular tachycardia, and 1 of them showed torsades de pointes. Other adverse events were nausea, water retention, APL differentiation syndrome, skin eruption, liver dysfunction, and peripheral neuropathy, all of which were quite tolerable. ATO therapy was remarkably effective for relapsed APL; however, postremission therapies were necessary to maintain a durable remission.
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PMID:Arsenic trioxide therapy in relapsed or refractory Japanese patients with acute promyelocytic leukemia: updated outcomes of the phase II study and postremission therapies. 1620 95

The study was aimed to detect expression rate of survivin gene in APL cell and to explore the relationship between its expression and clinical manifestation. PML/RARalpha and survivin mRNA expression were analyzed by using reverse transcriptase polymerase chain reaction (RT-PCR) technique. The results showed: (1) the survivin gene expression was detected in NB4 cell line. By treatment with ATRA, survivin mRNA expression in NB4 cell gradually decreased along with time delay and almost could not be detected at the 72th hour. (2) the positive and negative rate of survivin mRNA expression was 67% and 33% respectively, while in all 36 cases of de novo and relapse APL patients, the PML/RAR(alpha) fusion gene expression was positive. In 22 cases at remission stage, the PML/RARalpha fusion gene expression was negative, and the positive and negative rate of survivin mRNA expression was 36% and 64% respectively. The survivin mRNA expression positive rates in the de novo group, relapse group and PML/RARalpha fusion gene L-type positive group were obviously higher than those in remission period group (P < 0.05) and were significantly lower than those in acute leukemia group (P < 0.05, < 0.001). (3) whether the survivin mRNA expression was positive or negative in 36 cases of de novo and relapse APL patients, all the 36 cases could obtain complete remission. 4 APL patients with positive expression of survivin mRNA had DIC and serious infection (one patient died). The clinical symptom showed slight skin or mucosa bleeding, fever and asthenic in the patients with negative expression of survivin mRNA. When 2 APL patients with positive expression of survivin mRNA had been treated with ATRA, induction differentiation sign in their peripheral blood and bone marrow figures was not obvious. It is concluded that the survivin gene positive expression rate is lower in acute promyelocytic leukemia than that in any other types of leukemia and is related to clinical manifestation.
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PMID:[Expression of survivin gene in NB4 cell line and cells of acute promyelocytic leukemia and its anti-apoptosis and clinical significance]. 1663 9


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