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 cytogenetics of Hodgkin's disease (HD) is poorly understood. However, a t(2;5) is a common finding in CD30+ anaplastic large cell lymphoma (ALCL), a neoplasm thought by some to be closely related to HD. Recently, the t(2;5) has been cloned and found to represent fusion of the NPM gene with the ALK gene. Using Southern blot hybridization, one group has reported finding rearrangements of NPM in a proportion of cases of both ALCL and HD. In the current study, we used a highly sensitive reverse transcriptase-polymerase chain reaction methodology to analyze 34 cases of HD for the t(2;5). We were unable to find polymerase chain reaction evidence for the t(2;5) in any of the cases of HD, a result significantly different from our previous study of CD30+ non-Hodgkin's lymphomas (P < .02) including ALCL (P < .04), using identical methods. Our results do not support the hypothesis that the t(2;5) represents a common chromosomal abnormality for both HD and ALCL.
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PMID:Absence of the t(2;5) in Hodgkin's disease. 749 2

Although cytogenetic data suggest that the t(2;5)-(p23;q35) translocation occurs in many cases of CD30+ lymphomas, the exact frequency of this event is still unknown. To clarify this issue and its epidemiological characteristics, we examined 37 formalin-fixed, paraffin-embedded specimens of CD30+ lymphomas from the United States and Hong Kong by reverse transcriptase-polymerase chain reaction (RT-PCR) for the status of the NPM and ALK genes, which are typically juxtaposed by the t(2;5) translocation. Thirty-four cases were classified as anaplastic large cell lymphomas (ALCL), 2 cases as non-anaplastic large cell lymphomas (LCL), and 1 case as the small cell variant of CD30+ lymphoma. The t(2;5) translocation was detected in 6 cases (16%), including 3 of 18 American patients and 3 of 19 cases from Hong Kong. All cases had a 185-bp NPM RT-PCR product as detected by Southern blot analysis, indicating adequate preservation of mRNA. The 6 positive cases were among 4 of 34 adult lymphomas, as compared with 2 of 3 childhood cases. Five of 17 T-lineage cases were t(2;5)-positive, compared with 1 of 15 B-lineage cases and none of the 5 null-cell or mixed lineage cases. Our results therefore show that t(2;5) occurs at a low frequency among CD30+ lymphomas, at least in our adult-dominated series.
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PMID:Low frequency association of the t(2;5)(p23;q35) chromosomal translocation with CD30+ lymphomas from American and Asian patients. A reverse transcriptase-polymerase chain reaction study. 785 44

The CD30+ anaplastic large cell lymphoma (ALCL) represents a new lymphoma entity thought to be related to Hodgkin'S disease (HD), but displaying also its own unique features. Cytogenetic studies of ALCL have demonstrated the presence of a (2;5)(p23;q35) translocation in a substantial number of these cases. Recently, the t(2;5) has been cloned and described to represent fusion of the NPM gene with the ALK gene on chromosome 5. To better define the spectrum of lymphomas containing this abnormality we have analyzed 50 continuous human cell lines established from various types of non-Hodgkin's lymphoma, ALCL and HD. In a first step, the expression of the NPM-ALK fusion gene was examined by reverse transcriptase-polymerase chain reaction (RT-PCR). In a second step, the t(2;5)-carrying cells were tested for the translation of functional chimeric mRNA into a fusion protein by immuno-staining of single cells with a polyclonal antibody. The NPM-ALK fusion transcript and the p80 protein were detected in eight of nine ALCL cell lines. We were unable to find PCR evidence for the t(2;5) in any of the non-ALCL cell lines including other CD30+ cell lines. As all seven bona fide HD cell lines were NPM-ALK-negative, these results do not support the notion that the t(2;5) represents a chromosomal aberration common to both ALCL and HD.
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PMID:The (2;5)(p23;q35) translocation in cell lines derived from malignant lymphomas: absence of t(2;5) in Hodgkin-analogous cell lines. 855 20

The precise cellular origin and the pathogenetic mechanism(s) leading to the neoplastic transformation of anaplastic large cell lymphoma (ALCL) and the Reed-Sternberg cell of Hodgkin's disease (HD) remains largely uncertain. Classical cytogenetic analysis has shown a unique translocation involving bands 2p23 and 5q35 bands in a variable number of ALCLs. It has been recently shown that the nucleophosmin/B23 (NPM) gene (5q35) and a novel anaplastic lymphoma kinase (ALK; 2p23) are the fused genes of t(2;5). To investigate the presence and the precise frequency of NPM-ALK gene products among ALCL and HD cases, a large and well-characterized panel of ALCL (n = 49) and HD (n = 72) cases was studied using multiple strategies including reverse transcriptase-polymerase chain reaction (RT-PCR), Southern blot analysis, and immunohistochemistry. Overall, 6 (3 T and 3 null) of 49 ALCL and 3 (2 nodular sclerosis and 1 mixed cellularity) of 72 HD showed the presence of NPM-ALK transcripts by RT-PCR. NPM-ALK gene rearrangements were detected in all RT-PCR, NPM-ALK-positive ALCL by Southern blot analysis. Furthermore, in all the available cases we were able to show the presence of ALK-related protein using a specific polyclonal antiserum recognizing the cytoplasmic domain of ALK by immunohistochemistry. Our data show that NPM-ALK gene transcripts are identified in a subpopulation of ALCL, almost exclusively in T or null cell in origin, and in rare cases of HD. These findings show that some HD may be closely related to ALCL, giving us new insights on the pathogenesis and possibly biologic evolution of HD.
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PMID:Molecular characterization of the t(2;5) (p23; q35) translocation in anaplastic large cell lymphoma (Ki-1) and Hodgkin's disease. 856 33

The fusion gene NPM-ALK occurs in a subset of anaplastic large cell lymphomas (ALCLs), as a result of a chromosomal translocation, t(2;5) (p23;q35). It has been suggested that Hodgkin's disease (HD) and ALCL share a common histogenesis because of pathological and phenotypical similarities. In order to check this hypothesis, reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to detect the hybrid NPM-ALK gene in 30 tumour samples, including 22 lymph node biopsies from HD and eight ALCL specimens. The threshold level of sensitivity was shown to reach at least 1/10(4) by dilution experiments using cell lines as positive and negative controls. The expected 177 bp product indicative of the NPM-ALK rearrangement was identified in Karpas 299 and SUDHL-1 cell lines and in two out of eight ALCLs. The 22 HD cases were negative, even after two successive tests. Thus, since the ALCL-specific genetic alteration was absent in our series of HD cases, the present study does not support the hypothesis that HD and ALCL are histogenetically related entities.
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PMID:Molecular analysis of the NPM-ALK rearrangement in Hodgkin's disease. 868 74

The t(2;5) generates a chimeric NPM-ALK transcript encoded by the nucleophosmin NPM gene fused to the anaplastic lymphoma kinase gene ALK. Using a reverse transcriptase nested polymerase chain reaction assay we have detected NPM-ALK transcripts within CD30+ primary cutaneous lymphoma and lymphomatoid papulosis (LP). The t(2;5) was identified in 4 out of 9 CD30+ anaplastic lymphomas and in 1 out of 4 CD30+ pleomorphic lymphomas. Moreover, the t(2;5) was detected in 3 out of 10 LPs. All NPM-ALK-positive lymphomas and 1 NPM-ALK-positive LP exhibited a clonal rearrangement of the T cell receptor gamma-chain gene. The t(2;5) was detected in 2 cases of LP without other evidence for a clonal lymphoid population. To identify cells carrying the t(2;5) translocation, we used immunohistochemistry to detect the ALK-encoded p80 protein and in situ hybridization for the specific detection of NPM-ALK transcripts. Both p80 protein and NPM-ALK transcripts were expressed by anaplastic or large CD30+ lymphoma cells with positive NPM-ALK amplification. The presence of t(2;5) in a subset of CD30+ cutaneous lymphoma and LP may indicate a common pathogenesis with a subset of anaplastic nodal lymphoma.
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PMID:Detection of t(2;5)(p23;q35) translocation by reverse transcriptase polymerase chain reaction and in situ hybridization in CD30-positive primary cutaneous lymphoma and lymphomatoid papulosis. 870 87

Seven cases of large B-cell lymphoma which define a previously unrecognized subgroup are reported. Morphologically they are comprised of monomorphic large immunoblast-like cells, containing large central nucleoli, which tend to invade lymphatic sinuses. Superficially they resemble anaplastic large cell lymphoma (ALCL) but they lack CD30. These lymphomas express epithelial membrane antigen (as do ALCL), but also contain intracytoplasmic IgA of a single light chain type (five cases) and an endoplasmic reticulum-associated marker detected by antibody VS38. They lack lineage-associated leukocyte antigens with the exception of CD4 (5 of 5 cases) and CD57 (5 of 7 cases). They are labeled by antibodies detecting both the intracytoplasmic and extracellular regions of the ALK receptor kinase, suggesting that they express the full-length form of this molecule. This was confirmed by Western blotting (in the one case tested) which showed a band of 200 kD in tumor cell lysates, and by polymerase chain reaction (PCR) amplification of mRNA encoding intracellular and extracellular ALK sequences (in the two cases tested). There was no evidence by cytogenetics (one case analyzed) or reverse transcriptase-PCR (three cases tested) of the 2; 5 translocation or the resultant NPM-ALK gene, as is commonly found in ALCL. All but one of the patients were male and all but one were adults, and in all but the latter case the disease followed an aggressive course.
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PMID:A new subtype of large B-cell lymphoma expressing the ALK kinase and lacking the 2; 5 translocation. 905 27

To determine the significance of the t(2;5)(p23;q35) translocation in nodal and extranodal anaplastic large cell lymphoma (ALCL), we performed cytogenetic, molecular genetic, and immunohistochemical analyses of tumor tissues from 11 patients with CD30+ ALCL. Three of five patients with nodal ALCL had additional infiltration of the skin. Six patients had extranodal ALCL, two had primary intestinal ALCL, three had a primary cutaneous ALCL, and one had osseous ALCL. Cytogenetic investigation detected the t(2;5) in all patients with nodal ALCL but not extranodal ALCL. Tumor cells in t(2;5)+ lesions also stained immunohistochemically for p80NPM/ALK, whereas no staining for p80NPM/ALK was detected in extranodal ALCL. Two extranodal lesions had NPM/ALK fusion transcripts detected by nested reverse transcriptase-polymerase chain reaction. Fluorescence in situ hybridization analysis of these two lymphomas showed in one case a significant number (4%) of cells with a split hybridization signal, indicative of disruption of the NPM gene. Additional recurrent breakpoints observed in extranodal ALCL were 1p36, 6p25, and 8q24. Loss of genetic material occurred at 6q in one extranodal ALCL. Our results suggest that the t(2;5) more frequently plays a pathogenetic role in primary nodal than in extranodal ALCL and that this translocation may not be the primary event in some CD30+ ALCL.
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PMID:Chromosomal abnormalities in nodal and extranodal CD30+ anaplastic large cell lymphomas: infrequent detection of the t(2;5) in extranodal lymphomas. 959 98

A recurrent, reciprocal balanced translocation, t(2;5) (p23;q35), has been recognized in CD30+ anaplastic large-cell lymphomas (ALCL), a newly recognized subtype comprising approximately 5% of all non-Hodgkin's lymphoma (NHL). This translocation creates a novel fusion protein, NPM-ALK, which has transforming properties in vitro and can cause large-cell lymphoma in vivo when transfected into murine bone marrow. Multiple techniques including reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of NPM-ALK fusion transcripts, genomic DNA-PCR, RNA in situ hybridization, and fluorescence in situ hybridization (FISH) of metaphase chromosomes and interphase nuclei, and immunohistochemical detection of the 80 kilodalton protein (p80) derived from the NPM-ALK fusion have enabled surveys of normal and lymphoma tissues for evidence of the translocation. These studies suggest that expression of ALK protein, a novel orphan receptor tyrosine kinase, is normally confined to the nervous system. In lymphoma, NPM-ALK expression is most often seen in young patients with the monomorphic or small-cell variant of ALCL who present with advanced stage disease and have tumors with a CD30+, T- or null-cell phenotype. It is less frequently detected in older patients and in ALCL of pleomorphic histology. In addition, expression of NPM-ALK has been found in occasional CD30 negative B-cell lymphomas with diffuse large cell or immunoblastic histology. NPM-ALK is rarely, if ever, detected in Hodgkin's disease or secondary ALCL. Although initially found in primary nodal ALCL, recent studies suggest that NPM-ALK expression may occur in lymphoma at extranodal sites, including the skin; it remains controversial, however, whether CD30+ primary cutaneous lymphoma and its benign counterpart, lymphomatoid papulosis (LyP), express NPM-ALK in some cases. A retrospective study has suggested that expression of NPM-ALK is associated with a better overall 5-year survival; these results must be confirmed in prospective studies of patients with uniform staging and therapy to more fully understand the clinical significance of the t(2;5) and its novel chimeric protein, NPM-ALK.
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PMID:The t(2;5) in human lymphomas. 968 23

Several clinical and histopathologic features of 65 CD30+ cutaneous lymphoproliferations were evaluated for their diagnostic value between CD30+ primary versus secondary cutaneous lymphomas and for their prognostic significance. Primary cutaneous disease, spontaneous regression, and absence of extracutaneous spreading (but not age < or =60 years) were associated with a better prognosis. Epithelial membrane antigen, BNH9, CD15 or CBF.78 antigen were expressed in all types of cutaneous lymphoproliferations. However, epithelial membrane antigen immunoreactivity was more frequently expressed in CD30+ secondary cutaneous large-cell lymphoma. Among CD30+ primary cutaneous large-cell lymphoma, CD15 expression was only seen in localized skin lesions. P53 expression was not associated with spontaneous regression, extracutaneous spreading, or survival. Nested reverse transcriptase-polymerase chain reaction allowed the detection of NPM-ALK transcripts in 10 of 26 CD30+ primary and in 3 of 11 secondary cutaneous large-cell lymphomas. The ALK protein was detected in only 1 of 50 primary and in 4 of 15 secondary cutaneous CD30+ lymphoproliferations. In CD30+ primary cutaneous lymphoproliferation, NPM-ALK transcripts might be expressed by very rare normal or tumoral cells that are undetectable by immunohistochemistry. However, the expression of either NPM-ALK transcripts or ALK-protein was not correlated with prognosis or age in CD30+ cutaneous lymphoproliferations.
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PMID:Statistical evaluation of diagnostic and prognostic features of CD30+ cutaneous lymphoproliferative disorders: a clinicopathologic study of 65 cases. 977 81


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