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)

In this study, the reverse transcriptase-polymerase chain reaction (RT-PCR) for the reliable detection of multiple Epstein-Barr virus (EBV) transcripts was optimized and subsequently evaluated on lymphoma specimens. Since often only small lymphoma biopsies are available for analysis of EBV transcripts, several RT-protocols to generate cDNA from multiple targets were applied. These were multi-primer, oligo-dT primed and random hexamer primed cDNA synthesis. Multi-primer cDNA synthesis appeared to be the most suitable method for subsequent PCR analysis of EBV targets; simultaneous priming with up to 10 specific antisense primers (for EBNA1 and 2, LMP1 and 2, BARF0, BHRF1, BZLF1, C promoter activity and the RNA control genes U1A and c-abl) followed by PCR showed no loss of sensitivity compared to single-specific antisense priming. Transcripts were specifically detected in up to one EBV-positive JY cell in a background of 50,000 EBV-negative BJAB cells, with the exception of BZLF1 and QK spliced EBNA1 transcripts which could only be detected in 1000 and 10,000 EBV-positive cells, respectively. The analytical sensitivities of all the primers used in PCR, including BZLF1 and QK EBNA1 primers, were 1-10 copies of cloned RT-PCR products. The multi-primed RT-PCR was evaluated on lymphomas (n = 13). In cases with proper RNA quality, EBV expression patterns found were identical to those found in previous studies using single-primed RT-PCR assays. In conclusion, this study shows that multi-primed RT-PCR analysis can be used efficiently for EBV transcript analysis in small lymphoma biopsies, thereby facilitating studies concerning the role of EBV in lymphomagenesis.
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PMID:Multiprimed cDNA synthesis followed by PCR is the most suitable method for Epstein-Barr virus transcript analysis in small lymphoma biopsies. 907 13

Autologous peripheral blood stem cell transplantation (PBSCT) is replacing autologous bone marrow transplantation (BMT) in the treatment of leukemia. One of the potential advantages of autologous PBSCT is the possibility that peripheral blood stem cells (PBSC) are less likely to be contaminated by leukemic cells than bone marrow grafts. However, the major problem still remains the high incidence of leukemic relapse following autologous PBSCT, which may be caused by the reinfusion of PBSC contaminated by leukemic cells. Recently, we have developed a quantitative assay using competitive reverse transcriptase polymerase chain reaction that estimates the number of AML1/ETO transcripts in t(8;21) acute myelogenous leukemia (AML), in order to determine the degree of leukemic cell contamination in PBSC harvests, and to monitor minimal residual disease (MRD) quantitatively in patients with t(8;21) AML. Our data indicate that although PBSC harvests collected after consolidation chemotherapy are contaminated by leukemic cells, the degree of leukemic cell contamination decreases with repeated cycles of chemotherapy. Furthermore, the MRD in PBSC harvests is less than in the corresponding bone marrow obtained on the day of the PBSC collection. There appears to be no relationship between the number of AML1/ETO transcripts found in the infused PBSC harvests and the incidence of leukemic relapse following autologous PBSCT in our study. However, a substantial decrease of AML1/ETO transcripts was seen following autologous PBSCT. Thus, the quantitative analysis of AML1/ETO transcripts may be clinically useful in patients with t(8;21) AML.
Leuk Lymphoma 1997 Mar
PMID:Significance of quantitative analysis of AML1/ETO transcripts in peripheral blood stem cells from t(8;21) acute myelogenous leukemia. 913 Jun 15

Activation of T cells was shown to up-regulate the Fas ligand (FasL) which binds to the CD95 (APO-1/Fas) antigen and mediates activation-induced cell death (AICD) of activated T cells and T lymphoma cells. A recent report showed that mouse B cells express the FasL upon activation with lipopolysaccharide (LPS). We therefore asked whether activation of human B cells induces expression of FasL and whether AICD is mediated, as in T cells, through autocrine production of the FasL. We used human tonsillar B cells and Burkitt lymphoma cell lines which were activated by CD40 ligand, surface (s)IgM cross-linking, or LPS. Northern and Western blot analysis failed to detect FasL during B cell activation or AICD of both normal and malignant B cells. Low-level expression of FasL was detected by reverse transcriptase-polymerase chain reaction. Functional experiments, however, showed that FasL is not functionally expressed upon activation. IgM-mediated AICD in the tonsillar or Burkitt lymphoma B cells could not be inhibited by FasL blocking. Thus, our data show that, in contrast to T cells, activation of normal or malignant human B cells does not lead to functional FasL expression.
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PMID:Activation and activation-induced death of human tonsillar B cells and Burkitt lymphoma cells: lack of CD95 (Fas/APO-1) ligand expression and function. 913 Jun 60

We report a 3-year-old girl with minimally differentiated acute myeloid leukemia and chromosome 16 inversion (inv 16). Inv 16 is generally associated with acute myelomonocytic leukemia with dysplastic eosinophils in the bone marrow (AML-M4Eo). Recently, molecular analysis showed that a fusion gene is generated by this inversion between the CBFB gene on the q arm and the MYH11 gene on the p arm. Using reverse transcriptase-polymerase chain reaction analysis, we tried to detect CBFB/MYH11 chimeric mRNA in blasts from our patients, however, were unable to detect any chimeric mRNA in the blasts: The absence of CBFB/MYH11 transcripts in this case suggests that rare chimeric products might be formed as a result of inv 16 that could not be detected by the primer sets used in this study. Another possibility is that different genes are rearranged on the chromosome 16 with the inv 16. More detailed molecular analysis of this case might be necessary in order to elucidate these possibility. Analyzing leukemias with inv 16 which do not have a typical CBFB/MYH11 chimeric mRNA might lead to understanding an alternative pathogenesis for acute leukemia with inv 16.
Leuk Lymphoma 1997 Jan
PMID:Molecular analysis of minimally differentiated acute myeloid leukemia with chromosome 16 inversion. 915 61

The natural history of follicular lymphoma is to accrue large cells and become diffuse, resulting in progression/transformation to a higher-grade lymphoma. Histologic transformation occurs in approximately 60% of patients. Most often, follicular lymphomas transform into diffuse large cell lymphoma, but transformation to lymphomas classified using the Working Formulation as diffuse mixed, large cell immunoblastic, or small noncleaved cell also have been reported. Evidence of transformation may be found over time in sequential biopsy specimens, or may coexist in the same biopsy specimen. Here, we describe six cases of follicular lymphoma, large cell in five cases and mixed in one case, that transformed into a diffuse or sinusoidal CD30 antigen-positive large cell lymphoma with anaplastic cytologic features. Both the follicular and diffuse/sinusoidal components were of B-cell lineage, positive for the CD20 antigen and negative for the CD3 and CD43 antigens. The neoplastic cells expressed monotypic immunoglobulin light chain in five cases, three kappa and two lambda. BCL-2 protein was positive in four tumors, in both the follicular and diffuse/sinusoidal components in three cases, and only in the latter component in one case. Using the polymerase chain reaction (PCR), three of six cases had monoclonal immunoglobulin heavy chain gene rearrangements. The t(14;18) was not amplified in any case. Using reverse transcriptase (RT)-PCR, the t(2;5) was amplified in one of four tumors. This report highlights the heterogeneity of B-lineage anaplastic large cell lymphomas and indicates the need to consider antecedent follicular lymphoma in any B-cell lymphoma with anaplastic cytologic features.
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PMID:Transformation of follicular lymphoma into CD30-large cell lymphoma with anaplastic cytologic features. 915 76

Three clonally related lymphoma lines (Mac-1, Mac-2A and Mac-2B) derived from progressive stages of CD30+ cutaneous T-cell lymphoma were found to constitutively secrete GM-CSF. The secretion of GM-CSF was identified by the ability of cell line supernatants to stimulate growth of megakaryoblastic cell line M-07e. This supernatant-mediated stimulation was inhibited by anti-GM-CSF MoAb (>98% inhibition for Mac-1 and Mac-2B lines, and >95% for Mac-2A line). Synthesis of GM-CSF was confirmed, at the mRNA level, by reverse transcriptase PCR and, at the protein level, by ELISA. Quantification of GM-CSF in supernatants by ELISA showed that the Mac-1 line, derived from an early, clinically indolent stage of the lymphoma, produced much more GM-CSF (>1600 pg/ml) than Mac-2A and Mac-2B lines which were derived from a late, aggressive stage (30-50 and 50-120 pg/ml, respectively). Lack of inhibition of cell growth by anti-GM-CSF MoAb as well as lack of response to exogenous GM-CSF of cells cultured at low concentration have demonstrated that GM-CSF does not act directly as a growth factor for these lines. ELISA studies showed that GM-CSF concentration in serum and urine of the patient were not elevated (<5 pg/ml). From several other cell lines tested (two primary CD30+ ALCL, 2 CD30- non-lymphoblastic T-cell lymphomas and 4HD), only two HD lines with a T-lymphocyte phenotype secreted detectable amounts of GM-CSF. Our data show that cells lines from a patient with cutaneous T-cell lymphoma constitutively secrete GM-CSF, although this capacity is relatively diminished in lines developed from more advanced disease.
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PMID:Constitutive secretion of GM-CSF by three different cell lines derived from a single patient with a progressive cutaneous lymphoproliferative disorder. 916 23

The product of the protooncogene c-kit is the receptor for the hematopoietic cytokine stem cell factor (SCF). C-kit is expressed on leukemic cells of the erythroid, myeloid, and mast-cell lineage and SCF has a proliferative effect on some of these cells. The role of SCF and c-kit in lymphoid malignancies is much less clear. Here we review the role of c-kit in normal lymphopoiesis and summarize its role in lymphoid malignancies. C-kit is expressed in normal lymphopoiesis and its ligand SCF synergizes with IL-7 to enhance the proliferation of B- and T-cell progenitors. In malignant lymphopoiesis, c-kit can also be expressed in B and T-lymphoblastic cells from children with non Hodgkin's lymphoma (NHL) or acute lymphoblastic leukemia (ALL) when analyzed by the highly sensitive reverse transcriptase polymerase chain reaction (RT-PCR). While c-kit receptors were detected by flow cytometric (FCM) analysis on about 40% of fresh T-lymphoblastic biopsy tumor cell preparations or T-lymphoblastic cell lines, no receptors were detected on B-lymphoblastic fresh cells or cell lines from children with B-ALL or Burkitt's lymphoma (BL). Almost all of the lymphoblastic cells expressing c-kit protein responded to recombinant human (rh)SCF with a downregulation of c-kit receptors. A proliferative response was detected only in a minority of these cells. B-ALL or BL cell lines showed no response to rhSCF. Upregulation of c-kit in T-lymphoblastic cells could be demonstrated by the addition of IL-1 beta, TNF-alpha, TGF-beta or A23187, and downregulation by rhSCF or phorbol myristate acetate (PMA). Despite upregulation of c-kit mRNA, protein remained undetectable on B-ALL or BL cells in the presence of A23187. The metabolic state of the cells seemed to influence c-kit expression, since c-kit was upregulated in T-lymphoblastic cells by the addition of new medium. C-kit appears to play a role in the growth of some malignant T-lymphoblastic but not B-lymphoblastic cells.
Leuk Lymphoma 1997 Apr
PMID:C-kit receptors in childhood malignant lymphoblastic cells. 916 31

We used reverse transcriptase polymerase chain reaction (RT-PCR) assays to examine primary leukemic cells in on-study diagnostic bone marrow specimens from 642 children with newly diagnosed acute lymphoblastic leukemia (ALL) for the expression of MLL-AF4, E2A-PBX1, and BCR-ABL fusion transcripts. All PCR assays were performed centrally in the Children's Cancer Group ALL Biology Reference Laboratory. MLL-AF4 transcript was found in only 0.7% of the study population which excluded infants. E2A-PBX1 transcript was found in 2.5% of the study population and 3.3% of B-precursor cases. Expression was associated with massive hepatomegaly. BCR-ABL transcript was found in 2.3% of cases and correlated with older age, induction failure, and inferior event-free survival (EFS). RT-PCR assays allow rapid identification of patients with MLL-AF4 and BCR-ABL positive ALL. These patients have a poor outcome with contemporary therapy and rapid identification facilitates timely allocation to innovative treatment programs.
Leuk Lymphoma 1997 Jun
PMID:Expression of BCR-ABL, E2A-PBX1, and MLL-AF4 fusion transcripts in newly diagnosed children with acute lymphoblastic leukemia: a Children's Cancer Group initiative. 925 Jul 88

We report a case of Philadelphia (Ph)-positive AML in which interphase fluorescence in situ hybridization (FISH) analysis was performed from diagnosis throughout the course of therapy using major (M-) breakpoint cluster region (BCR)/minor (m-) BCR and ABL cosmid probes. We also investigated the existence of the M-BCR or m-BCR at the RNA or DNA level by the reverse transcriptase polymerase chain reaction and Southern blot analysis, respectively. Complete remission with a normal karyotype was achieved after several regimens of chemotherapy and peripheral blood stem cell transplantation (PBSCT), but relapse occurred and his cells became 100% Ph-positive. We detected the m-BCR/ABL fusion gene by interphase FISH analysis using an m-BCR/ABL translocation probe, and found that FISH analysis was useful for classifying the BCR, identifying minimal residual disease, and for predicting imminent relapse after chemotherapy and PBSCT.
Leuk Lymphoma 1997 Jun
PMID:Sequential interphase FISH analysis of m-BCR/ABL chimeric gene-positive cells in Ph-positive acute myeloid leukemia. 925 Aug 5

The tie gene encodes a receptor tyrosine kinase that together with its thus far unidentified ligand appears to play a distinct role in the regulatory pathway of early hematopoiesis and angiogenesis. Here, we attempted to define the possible involvement of tie in the pathobiology of hematopoietic malignancies by examining tie mRNA expression in human leukemia and lymphoma cells. We used a large panel of 93 well-characterized human continuous leukemia-lymphoma cell lines as model systems for the various hematopoietic cell lineages. At the Northern blot level, none of the 27 lymphoid leukemia or lymphoma-derived cell lines (originating from four B-precursor leukemia, four B-cell leukemia, four B-cell non-Hodgkin's lymphoma, two myeloma, two Burkitt lymphoma, four T-cell leukemia, five Hodgkin lymphoma, two anaplastic large cell lymphoma) tested expressed tie transcripts, whereas 23/42 (55%) of the myeloid cell lines analyzed expressed tie mRNA: in detail, 15 of 20 (75%) megakaryocytic, five of 11 (45%) erythroid, three of seven (43%) myelocytic and none of four monocytic cell lines were tie mRNA positive. In the reverse transcriptase-polymerase chain reaction analysis, which can detect very low levels of mRNA expression, all 12 myeloid cell lines and 19 of 39 (48%) lymphoid cell lines were positive. In experiments aimed at inducing cellular differentiation over an incubation period of 4 days, the phorbol ester PMA strongly enhanced tie mRNA expression in one erythroid and in one myelocytic cell line, but (like thrombopoietin) down-regulated tie mRNA expression in two megakaryocytic cell lines. Taken together these results indicate that tie is predominantly expressed in leukemia cells derived from the myeloid cell lineages (and here in particular in megakaryoblastic cells) and not in lymphoid leukemia cells. These observations provide some evidence for the hypothesis that tie is a receptor for a regulatory factor involved in normal and plausibly also leukemic hematopoiesis.
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PMID:Expression of tie receptor tyrosine kinase in human leukemia cell lines. 930 79


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