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)

Detection of BCR-ABL transcripts in chronic myeloid leukaemia (CML) is used to confirm the diagnosis and to monitor residual disease. Quantitative techniques are required to predict response to therapy or early relapse. We have evaluated an assay in which transcription-mediated amplification (TMA) of BCR-ABL and ABL transcripts is achieved using reverse transcriptase and RNA polymerase. The products are quantified in the hybridisation protection assay (HPA) using acridinium ester-labelled DNA probes and chemiluminescence. The method is a single tube procedure which uses small amounts of RNA (<500 ng/triplicate analysis), is technically simple (requiring just two waterbaths and a luminometer), rapid (total assay time <4 h) and sensitive (capable of detecting one BCR-ABL-positive K562 cell in the presence of 10(4)-10(5) BCR-ABL-negative cells). BCR-ABL signals from patient RNA samples were quantified relative to known amounts of K562 RNA and normalised to levels of ABL. BCR-ABL/ABL ratios ranged from 0.15 to 1.59 (median 0.65) in RNA from diagnostic blood or bone marrow of 18 CML patients and were < or =0.0001 in 20 normal controls. Sequential samples analysed from six CML patients post-allogeneic bone marrow transplantation who relapsed and received donor lymphocyte infusions showed BCR-ABL/ABL ratios which reflected patient status or treatment. A BCR-ABL/ABL ratio of 0.01 served as a useful arbitrary indicator value, with results above and below this value generally correlating with relapse or remission, respectively.
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PMID:Transcription-mediated amplification and hybridisation protection assay to determine BCR-ABL transcript levels in patients with chronic myeloid leukaemia. 1189 44

Acute promyelocytic leukaemia (APL) is characterized by the t(15;17)(q22;q21) leading to the formation of PML-RARalpha and RARalpha-PML fusion genes which provide suitable targets for the assessment of minimal residual disease (MRD). Studies have focused upon detection of PML-RARalpha because, although assays for RARalpha-PML transcripts are more sensitive, they are not applicable to 25% of cases. Among patients receiving standard therapy (ATRA and anthracycline-based chemotherapy), qualitative assays using a nested reverse transcriptase-polymerase chain reaction (RT-PCR), which typically achieve sensitivities of 1 in 10(4), have been found to provide independent prognostic information suitable for directing an approach to treatment. Detection of PML-RARalpha at the end of consolidation, or subsequent recurrence of PCR positivity, heralds relapse, which may, however, be averted by additional therapy leading to improvements in survival for this "high-risk" subgroup of patients. MRD analysis has also proved of value in predicting response to autologous transplant procedures undertaken in second complete remission and in directing the need for additional therapy in the post-transplantation setting. Overall, these studies undertaken within the context of a relatively homogeneous disease entity confirm that MRD monitoring provides independent prognostic information, serving as a valuable model for improving treatment strategy in other molecularly defined subsets of acute myeloid leukaemia (AML). Nevertheless, conventional nested RT-PCR assays fail to detect residual disease in a significant proportion of patients who ultimately relapse, which may be a reflection of RNA quality and/or assay sensitivity. Therefore, it is hoped that "real-time" quantitative RT-PCR technology (RQ-PCR) which permits quantification of fusion gene transcripts in relation to endogenous control genes will be even more predictive of outcome and achieve greater standardization of MRD detection in the context of large-scale clinical trials.
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PMID:The significance of minimal residual disease in patients with t(15;17). 1198 21

Minimal residual disease (MRD) evaluation in breast cancer patients is a promising tool to improve current staging procedures. In a previous work employing a CK-19-based reverse transcriptase-polymerase chain reaction (RT-PCR) technique for MRD detection, we identified a group of women who exhibited persistent negativity for this assay and for whom this technique was considered noninformative. In order to improve the yield of MRD detection in these patients, we evaluated the usefulness of RT-PCR detection of c-erbB-2 expression. We were able to detect up to 1 MCF-7 cell (positive for c-erbB-2 expression) in a mixture of 1,000,000 CCRF-CEM cells (negative for c-erbB-2 expression). We evaluated the specificity of this technique in the peripheral-blood mononuclear cells (PBMCs) of 20 healthy women and found that 2 of these women were positive for c-erbB-2 expression. In the PBMCs of a group of 16 women with breast cancer, 25% of the samples were positive for c-erbB-2 expression before chemotherapy. Except for race (P = 0.017), no other significant correlations were found, including c-erbB-2 expression in the primary tumor by immunoperoxidase. Interestingly, in the subgroup of 6 patients for whom this technique was informative, we found that 80% of the samples obtained while on chemotherapy were negative compared to only 10% obtained off treatment (P = 0.017). Additionally, 2 patients for whom CK-19 expression was noninformative had at least 1 c-erbB-2-positive sample. We conclude that this technique might be useful for MRD detection in breast cancer patients, but further studies are necessary to confirm our findings.
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PMID:Peripheral blood c-erbB-2 expression by reverse transcriptase-polymerase chain reaction in breast cancer patients receiving chemotherapy. 1219 78

Adenocarcinoma of the pancreas is associated with the worst survival of any form of gastrointestinal malignancy. In spite of the progress in surgical treatment, resulting in increasing resection rates and a decrease in treatment-related morbidity and mortality, the true figures of cure are even today below 3%. The dissemination of pancreatic cancer behind the local tissue compartments restricts the short-term (< 3 years) and long-term outcome for patients who have undergone resection. By histological evaluation, less than 15% of the patients undergoing R(0) resection have a pN(0) status, more than 60% suffer from lymph angiosis carcinomatosa, and more than 50% suffer extrapancreatic nerve plexus infiltration. Hematoxylin and eosin-negative lymph nodes were found to be cancer positive when reverse transcriptase polymerase chain reaction (RT- PCR) or immunostaining was applied to the HE-negative lymph nodes. Cancer of the uncinate process has a very poor prognosis because there are no early symptoms; vessel wall involvement occurs early and frequently; a high association of liver metastasis exists as well. Surgery offers a low success rate, but it provides the only chance of cure. Ductal pancreatic cancer is diagnosed in more than 95% of the cases in an advanced stage; potentially curative resection can be performed only in about 10%-15% of these patients. Major contributions of surgery to improved treatment results are the reduction of surgical morbidity--e.g., early postoperative local and systemic complications--and a decrease of hospital mortality below 3%-5%. In most recently published prospective trials, R(0) resection has been reported to result in an increase in short-term survival beyond that recorded for patients with residual tumor. However, R(0) resection fails to improve long-term survival. In many published R(0) series, standard tissue resection of pancreatic head cancer with the Kausch-Whipple procedure failed to include remote cancer cell-positive tissues in the operative specimen; e.g., N(2)-lymph nodes, nerve plexus, and perivascular extrapancreatic and retropancreatic tissues were not excised. Cancer recurrence after so-called R(0) resection with curative intent is frequently the consequence of cancer left behind. Thus, long-term survival (> 5 years) is observed in a very small group of patients, contradicting the published 5-year actuarial survival rates of 20%-45% for resected patients. The assessment of clinical benefit from surgical or medical cancer treatment should therefore be based on several end points, not only on actuarial survival. Publication of actuarial survival figures must include the number of observed (actual) survivals, the definition of the subset of patients followed after resection, and the total number of patients in the study group; anything less is misleading. In reporting pancreatic cancer treatment trial results after oncological resections, more convincing primary end points to evaluate treatment efficacy are median survival (in months), actual survival at 1-5 years, and progression-free survival (in months). In series with multimodality treatment, clinical benefit response as well as quality of life measurements using the EORTC Quality of Life index C30 (QLQ-C30) are of importance in evaluating survival data. Adjuvant treatment improves survival after oncological resection; however, the short-term and long-term benefit after adjuvant chemotherapy in R(0) as well as in R(1)-(2) resected patients has not yet been underscored by data from controlled clinical trials. The survival benefit (median survival time) of adjuvant chemotherapy or radiochemotherapy has been demonstrated to be 6-10 months. Therefore, after oncological resection of pancreatic cancer each patient should be offered adjuvant treatment. A neoadjuvant treatment protocol for pancreatic cancer, however, has not been established.
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PMID:Treatment of pancreatic cancer: challenge of the facts. 1292 7

A significant proportion of chronic myeloid leukemia (CML) patients achieve a major cytogenetic remission (MCR) to imatinib therapy after failing interferon (IFN) alpha-based protocols. We sought to determine levels of residual disease in patients with MCR using various molecular methods and to establish a relation between residual BCR-ABL transcript levels and rate of relapse in complete cytogenetic remission (CCR). Response was measured by conventional cytogenetic analysis, hypermetaphase and interphase fluorescence in situ hybridization (HM-FISH, IP-FISH) of bone marrow (BM) cells, qualitative nested and quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for BCR-ABL transcripts. We investigated 323 peripheral blood (PB) and BM samples from 48 CML patients who achieved a complete (Ph+ 0%; n=41) or partial (Ph+ 1-34%; n=7) cytogenetic remission after 3-20 months of imatinib therapy. Prior to imatinib, 35 patients were in chronic phase (CP), eight in accelerated phase (AP), four in myeloid and one in lymphoid blast crisis. HM-FISH results correlated with ratios BCR-ABL/ABL in PB and BM. In patients with CCR, residual disease was detectable by HM-FISH (31%), IP-FISH (18%), and RT-PCR (100%). During follow-up, BCR-ABL became undetectable in two patients (one CP, one AP) by both nested and quantitative RT-PCR. CCR is ongoing in 30 evaluable patients, 11 patients have relapsed. At the time of best response, median ratios BCR-ABL/ABL were 2.1% (range 0.82-7.8) in patients with subsequent relapse and 0.075% (range 0-3.9) in patients with ongoing remission (P=0.0011). All 16 CP patients, who achieved ratios BCR-ABL/ABL <0.1% as best molecular response are in continuous remission, while 6/13 patients (46%) with ratios >/=0.1% have relapsed (P=0.0036). We conclude that: (i) in patients with CCR to imatinib, HM-FISH and RT-PCR usually reveal residual BCR-ABL+ cells; (ii) RT-PCR results derived from PB and BM are comparable in CP CML; and (iii) low levels of residual disease with ratios BCR-ABL/ABL &<0.1% are associated with continuous remission.
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PMID:Molecular monitoring of response to imatinib (Glivec) in CML patients pretreated with interferon alpha. Low levels of residual disease are associated with continuous remission. 1297 Jul 65

Recent progress of molecular and cytogenetic techniques has led to remarkable advances in molecular diagnosis of pediatric malignancies, including malignant bone and soft tissue sarcoma (MSTS). Fusion genes, such as EWS-FLI1 and PAX3-FKHR, were cloned at the chromosome breakpoints of t(11;22) and t(2;13) in Ewing's sarcoma and rhabdomyosarcoma, respectively. Minimal residual disease can be detected by reverse transcriptase-polymerase chain reaction using these translocations. These fusion genes contribute to differential diagnosis of pediatric small round cell tumor, which was difficult to diagnose morphologically. Some of these fusion genes, including SYT-SSX in synovial sarcoma and EWS-FLI1 in Ewing sarcoma, have been reported to be associated with prognosis. Recently, genome-wide searches using microarray and single nucleotide polymorphisms have been performed in pediatric malignancies. These advances have led to the increased importance of molecular diagnosis as well as morphological diagnosis. We review here the recent progress of molecular diagnosis in pediatric malignancies.
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PMID:[Recent progress of molecular diagnosis in pediatric malignancies]. 1451 98

Despite curative tumor resection, about 30%-50% of patients with locally advanced gastrointestinal (GI) carcinoma develop tumor recurrence which may be caused by pre- or intraoperative tumor cell dissemination. We examined the combination of optimized density gradient centrifugation with a CK-20 reverse transcriptase-polymerase chain reaction to detect and quantify circulating tumor cells in peripheral blood. Peripheral venous blood (20 ml) of patients with GI carcinomas was collected during primary tumor staging before and after the endoscopy procedure. CK-20 expression in peripheral venous blood was found in 22 of 82 patients (26.8%) with a nonsignificant difference between the upper GI tract (23.9%) and the lower GI tract (30.5%). The correlation with clinical outcome (24-month-survival) revealed a significantly worse prognosis (p < 0.05) of CK-20-positive patients with carcinoma of the upper GI tract and a trend toward a worse prognosis for patients with carcinoma of the lower GI tract. Quantification of CK-20 expression in peripheral blood showed a significantly higher circulating CK-20 copy number (median: 2816) in patients with metastatic tumors than in those with non-metastatic tumors (median: 983) (p < 0.05). For a subset of 42 primarily operated patients, we correlated the detection rate with UICC (International Union Against Cancer) staging categories. In contrast to the upper GI tract, the detection rate of patients with carcinoma of the lower GI tract showed a trend toward tumor size (pT) and a significant correlation with the presence of distant metastases (pM) (p < 0.01) and the postoperative residual tumor status (R) (p < 0.01). The endoscopy procedure did not lead to an increased detection of CK-20 expression.
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PMID:Prognostic impact of CK-20-positive cells in peripheral venous blood of patients with gastrointestinal carcinoma. 1577 Mar 78

Highly active antiretroviral therapy (HAART) does not lead to viral eradication, due to HIV-1 residual disease. We investigated whether the cervicovaginal tract serves as a viral reservoir. Seven out of eight cervicovaginal fluids were positive for cell-free HIV-1, by supersensitive reverse transcriptase-polymerase chain reactions (RT-PCR), with a detection limit of 1 copy/ml. No viral outgrowth, intracellular proviral DNA, or viral RNA was detected from cervicovaginal lavage and ecto- and endocervical cells. The cervicovaginal tract of patients on HAART is likely not a major solid tissue reservoir for HIV-1. Nonetheless, the presence of even low cell-free HIV-1 RNA in cervicovaginal secretions continues to suggest the importance of practicing protected sex, even in the era of HAART.
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PMID:HIV type 1 cervicovaginal reservoirs in the era of HAART. 1613 11

Chronic myeloid leukemia (CML) relapse after allogeneic stem cell transplantation (SCT) is a relatively frequent situation, which is correlated to disease status, time from diagnosis to transplant and T-cell depletion. We evaluated the potential for early minimal residual disease (MRD) BCR-ABL quantification to predict relapse of CML patients receiving allogeneic SCT. Minimal residual disease was analyzed by real-time quantitative reverse transcriptase-polymerase chain reaction (RQ-PCR) at day 100 (d100) in 38 patients with >1 year follow-up after conventional non-T-cell-depleted SCT. Normal ABL control values from 1724 follow-up blood samples were used to define an RQ-PCR amplifiability index and the limits of reliable use of BCR-ABL ratios. We then compared the 14 patients with a high-level d100 BCR-ABL/ABL ratio (> or = 10(-4)) to that of the 24 patients with a negative/low-level ratio (<10(-4)). Despite being comparable for all classical parameters, the incidence of relapse was significantly higher in the high MRD group (11/14 (79%)) compared to that of the low/negative MRD group (7/24 (29%)) (P = 0.009), with d100 MRD values representing an independent risk factor of relapse and disease-free survival, but not of overall survival, in multivariate analysis. These data should facilitate risk-adapted post-transplant immunosuppression and/or tyrosine kinase inhibitor therapy based on an early evaluation of MRD.
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PMID:Prediction of relapse by day 100 BCR-ABL quantification after allogeneic stem cell transplantation for chronic myeloid leukemia. 1654 Nov 40

We report the first case of a tumor of the Ewing sarcoma family of tumors arising from the urinary bladder 3 years after chemotherapy for acute lymphoblastic leukemia. A 16-year-old boy complained of macrohematuria and dysuria during the posttreatment follow up of his acute lymphoblastic leukemia. Ultrasonography and computed tomography revealed a 1-cm sized intravesical tumor. The tumor was transurethrally resected with no residual tumor at the margin. Histopathologic analyses revealed a small round blue cell tumor with positive staining for CD99 antibody. EWS-FLI1 fusion transcripts were detected in the tumor tissue by reverse transcriptase polymerase chain reaction. These findings support the diagnosis of Ewing sarcoma family of tumor. After adjuvant multidrug chemotherapy, the patient has shown no evidence of disease for more than 2 years.
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PMID:A case of a ewing sarcoma family tumor in the urinary bladder after treatment for acute lymphoblastic leukemia. 1809 Sep 34


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