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)

Hepatitis C virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Studies of HCV replication and pathogenesis have so far been hampered by the lack of an efficient tissue culture system for propagating HCV in vitro. Although HCV is primarily a hepatotropic virus, an increasing body of evidence suggests that HCV also replicates in extrahepatic tissues in natural infection. In this study, we established a B-cell line (SB) from an HCV-infected non-Hodgkin's B-cell lymphoma. HCV RNA and proteins were detectable by RNase protection assay and immunoblotting. The cell line continuously produces infectious HCV virions in culture. The virus particles produced from the culture had a buoyant density of 1.13 to 1.15 g/ml in sucrose and could infect primary human hepatocytes, peripheral blood mononuclear cells (PBMCs), and an established B-cell line (Raji cells) in vitro. The virus from SB cells belongs to genotype 2b. Single-stranded conformational polymorphism and sequence analysis of the viral RNA quasispecies indicated that the virus present in SB cells most likely originated from the patient's spleen and had an HCV RNA quasispecies pattern distinct from that in the serum. The virus production from the infected primary hepatocytes showed cyclic variations. In addition, we have succeeded in establishing several Epstein-Barr virus-immortalized B-cell lines from PBMCs of HCV-positive patients. Two of these cell lines are positive for HCV RNA as detected by reverse transcriptase PCR and for the nonstructural protein NS3 by immunofluorescence staining. These observations unequivocally establish that HCV infects B cells in vivo and in vitro. HCV-infected cell lines show significantly enhanced apoptosis. These B-cell lines provide a reproducible cell culture system for studying the complete replication cycle and biology of HCV infections.
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PMID:Establishment of B-cell lymphoma cell lines persistently infected with hepatitis C virus in vivo and in vitro: the apoptotic effects of virus infection. 1252 48

The chromosomal translocation t(11;18) is a unique chromosomal aberration associated with mucosa-associated lymphoid tissue lymphoma. API2 and MALT1 genes have been identified around this translocation. We attempted to find chromosomal abnormalities focusing mainly on the t(11;18) translocation in formalin-fixed, paraffin-embedded tissues of ocular adnexal lymphoproliferative disorders using multiplex reverse transcriptase-polymerase chain reaction and/or two-color interphase fluorescence in situ hybridization. By these methods, the t(11;18) translocation was detected in 1 of 8 patients with reactive lymphoid hyperplasia (13%), 3 of 23 with mucosa-associated lymphoid tissue lymphoma (13%), and 2 of 14 with diffuse large B-cell lymphoma with/without mucosa-associated lymphoid tissue lymphoma (14%). Moreover, we performed fluorescence in situ hybridization analysis to detect any numerical aberration of chromosomes 3, 7, 12, and 18 on some specimens nonselectively. No numerical chromosomal abnormalities were detected in 3 cases of reactive lymphoid hyperplasia, whereas three of four cases of mucosa-associated lymphoid tissue lymphoma and all four cases of diffuse large B-cell lymphoma with/without mucosa-associated lymphoid tissue lymphoma components exhibited one or more abnormalities. These findings indicate a possibility that at least in the ocular adnexa, some diffuse large B-cell lymphomas are derived from mucosa-associated lymphoid tissue lymphomas.
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PMID:Involvement of the chromosomal translocation t(11;18) in some mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas of the ocular adnexa: evidence from multiplex reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization on using formalin-fixed, paraffin-embedded specimens. 1274 51

Expression of ALK protein by lymphoid cells and the description of variant anaplastic lymphoma kinase (ALK) translocations have typically been restricted to cases of T-cell and null anaplastic large-cell lymphoma (ALCL). All such cases result from a novel fusion created by the ALK gene on chromosome 2p23 and NPM on 5q35 or other variant translocation partners. A rare variant of diffuse large B-cell lymphoma (DLBCL), originally described in 1997, was thought to overexpress full-length ALK in contrast to a chimeric protein characteristic of ALCL. However, full-length ALK protein lacks tyrosine kinase activity and thus the mechanism of oncogenesis has remained elusive. We describe 6 cases of ALK+ DLBCL characterized by a simple or complex t(2;17)(p23;q23) involving the clathrin gene (CLTC) at chromosome band 17q23 and the ALK gene at chromosome band 2p23. All cases were studied using fluorescence in situ hybridization (FISH), complemented in one case with standard cytogenetic analysis, multicolor karyotyping (M-FISH), and reverse transcriptase-polymerase chain reaction. These results clearly demonstrate that most cases of ALK+ DLBCL share the same mechanism of deregulated ALK expression. Moreover, these results demonstrate the presence of CLTC-ALK fusions in these tumors and extend the list of diseases associated with this genetic abnormality to include classical T-cell or null ALCL, ALK+ DLBCL, and inflammatory myofibroblastic tumors.
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PMID:ALK-positive diffuse large B-cell lymphoma is associated with Clathrin-ALK rearrangements: report of 6 cases. 1276 27

While most anaplastic lymphoma kinase (ALK)-positive non-Hodgkin lymphomas (NHLs) are of T-cell lineage, a small number of B-lineage tumors with plasmablastic morphology and expression of the full-length ALK protein have been described in the literature. All of these reported tumors lacked the NPM-ALK fusion transcript. There is controversy regarding the existence of ALK fusion-positive B-cell NHL, with many investigators contending that ALK fusions are expressed uniquely in T- or null-cell lymphomas. Here we describe 2 well-characterized cases of ALK-positive B-cell lymphoma expressing the NPM-ALK fusion. Both tumors occurred in pediatric patients and showed poor response to chemotherapy. Each had plasmablastic morphology, showed immunoglobulin A restriction, and was ALK positive and CD30- by immunohistochemistry. One tumor showed the t(2;5)(p23;q35) chromosomal translocation by conventional cytogenetics. Both were positive for NPM-ALK by reverse transcriptase-polymerase chain reaction. Thus, ALK-positive plasmablastic B-cell lymphomas are more heterogeneous at the molecular level than previously recognized.
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PMID:ALK-positive plasmablastic B-cell lymphoma with expression of the NPM-ALK fusion transcript: report of 2 cases. 1281 58

We analysed the immunophenotypic and molecular expression of BCA-1 (B-cell-specific chemokine) and CXCR5 (BCA-1 receptor) in normal skin and different cutaneous lymphoproliferative disorders (cutaneous T-cell lymphoma (CTCL); cutaneous B-cell lymphoma (CBCL); cutaneous B-cell pseudolymphoma (PCBCL)), with the aim of investigating their possible involvement in the pathogenesis of cutaneous B-cell disorders. BCA-1 and CXCR5 were constantly expressed in CBCL and PCBCL, but not in normal skin and CTCL. BCA-1 and CXCR5 were constantly coexpressed by CD22+ B-cells, while CD35+ follicular dendritic cells coexpressed BCA-1 in PCBCL cells only. In low grade CBCL, as compared with high grade CBCL, the intensity of CXCR5 expression on neoplastic CD22+ cells was lower than that of BCA-1. The image analysis of reverse transcriptase-polymerase chain reaction (RT-PCR) products showed a significant quantitative difference between PCBCL/low grade CBCL and high grade CBCL. The above findings, although only observed in a small series of patients, are in keeping with findings in MALT gastric and gastric MALT lymphomas, adding further evidence of the close similarities between CBCL and MALT lymphomas.
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PMID:BCA-1, A B-cell chemoattractant signal, is constantly expressed in cutaneous lymphoproliferative B-cell disorders. 1285 71

Pathological features and genomic basis of a rare case of ALK(+), CD30(-), CD20(-) large B-cell lymphoma were analyzed. A 36-year-old Japanese female was admitted because of lumbago and constitutional symptoms. Physical examination and laboratory tests showed anemia (hemoglobin, 7.5 g/dL), mild hepatosplenomegaly, and immunoglobin G (IgG) lambda-type monoclonal gammopathy (IgG, 2782 mg/dL). The lymphoma spread exclusively in extranodal sites such as bone marrow, liver, spleen, ovary, and muscle. Biopsy specimens obtained from the ovary showed monomorphic proliferation of large immunoblastic cells with basophilic cytoplasm, round-shaped nuclei with a high nuclear to cytoplasmic ratio, and prominent single nucleolus. Immunostaining with anti-anaplastic lymphoma kinase (ALK) antibody, ALK1, showed finely granular cytoplasmic staining pattern. These cells were also positive for epithelial membrane antigen, CD4, CD19, CD38, CD138, cytoplasmic IgG, and lambda chain, but negative for CD30 (Ber-H2), CD56, CD57, and other T- and B-cell markers. Southern blot analyses revealed that Ig heavy and lambda light chain genes, but not T-cell receptor (TCR) beta gene, were clonally rearranged. Chromosomal analyses by conventional G-banding, spectral karyotyping, and fluorescence in situ hybridization showed complex abnormality involving 2p23, and chromosome 2 was translocated to chromosome 17. As 2;17 translocation resulting in the fusion of clathrin heavy chain (CLTC) gene with ALK was previously reported in inflammatory myofibroblastic tumor, we performed reverse transcriptase-polymerase chain reaction and demonstrated that the lymphoma cells contained CLTC-ALK fusion transcript. Under the diagnosis of ALK(+), CD30(-), CD20(-) large B-cell lymphoma, she was treated with conventional combination chemotherapies. However, the lymphoma was primarily chemotherapy resistant, and the patient died 11 months after admission. We consider that this case confirms the existence of ALK(+), CD30(-), CD20(-) large B-cell lymphomas proposed by Delsol et al. (16) and further provides relevant information regarding their clinicopathological features and cytogenetics.
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PMID:ALK+, CD30-, CD20- large B-cell lymphoma containing anaplastic lymphoma kinase (ALK) fused to clathrin heavy chain gene (CLTC). 1292 Feb 29

To determine the specific gene expression in B-cell lymphoma subtypes, we compared expression profiles of cell lines from transformed follicular lymphoma (tFL), Epstein-Barr virus-negative (EBV(-)) Burkitt's lymphoma (BL) and EBV(+)BL. Complementary DNAs were synthesized from these cell lines and hybridized with the Atlas Human 1.2 Array membrane. Hierarchical clustering analysis based upon the levels of 43 genes highlighted characteristic expression patterns of the 3 lymphoma subtypes. Genes expressed at higher levels in tFL than EBV(-)BL and EBV(+)BL included calcium/calmodulin-dependent protein kinase I (CAMK1) and mitogen-activated protein kinase 10 (MAPK10). EBV(-)BL was characterized by high-level expression of amyloid beta precursor protein (APP), heat shock 27 kD protein 1 (HSPB1) and mothers against decapentaplegic homolog 1 (MADH1). Gardner-Rasheed feline sarcoma viral oncogene homolog (FGR) was the most significant gene to delineate EBV(+)BL. A subtype prediction algorithm using 34 genes correctly classified 22 (92%) of 24 lymphomas into FL/tFL, EBV(-)BL or EBV(+)BL. By comparison with normal reference B-cell materials, the expression patterns of the selected genes were characteristic of lymphomas. We extended the clustering analysis to cell lines from de novo diffuse large B-cell lymphoma (DLBCL). The DLBCL cell lines were either separated from the former 3 lymphoma subtypes or segregated with EBV(+)BL, possibly reflecting variable genetic abnormalities. The associations of CAMK1 with tFL, APP and MADH1 with EBV(-)BL, FGR with EBV(+)BL, and BCL2 with tFL and DLBCL were confirmed by real-time quantitative reverse transcriptase-mediated polymerase chain reaction assays. This study has provided new molecular markers, expressions of which are closely associated with B-cell lymphoma subtypes.
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PMID:Comparison of gene expression profiles of lymphoma cell lines from transformed follicular lymphoma, Burkitt's lymphoma and de novo diffuse large B-cell lymphoma. 1296 75

In the present study, 62 cases of ocular adnexal lymphoproliferative disorders were reviewed clinicopathologically. Of them, 51 were extranodal marginal zone B-cell lymphoma (MALT lymphoma), five were diffuse large B-cell lymphoma (DLBCL), one was peripheral T-cell lymphoma, one was NK/T cell lymphoma, nasal type, and four were reactive lymphoid hyperplasia. These lymphoma cases showed a favorable clinical course and localized disease, except for the case of NK/T cell lymphoma, although 19 cases (32.8%) had a recurrence of disease. To clarify the correlation between BCL10 protein expression and API2-MALT1 gene rearrangement, the 51 cases of MALT lymphoma and 5 cases of DLBCL were analyzed by immunohistochemical and RT-PCR methods. Nuclear BCL10 expression was identified in 58% of MALT lymphoma cases, but not in any DLBCL cases. There was no evidence of a correlation between aberrant nuclear BCL10 expression and the clinical parameters examined in the present study. API2-MALT1 transcription was not demonstrated in either the MALT lymphoma cases or the DLBCL cases studied using a multiplex one-tube reverse transcriptase-PCR method. These findings indicate that the nuclear expression of BCL10 is unlikely to correlate with the API2-MALT1 fusion gene in ocular adnexal MALT lymphoma.
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PMID:No evidence of a correlation between BCL10 expression and API2-MALT1 gene rearrangement in ocular adnexal MALT lymphoma. 1467 90

Human herpes virus type 8 (HHV8) has been strongly associated with Kaposi sarcoma, primary effusion lymphoma (PEL), and Castleman's disease. To our knowledge, infection by this virus has not been strongly associated with other hematopathologic malignancies. We examined five oral cavity lymphomas from men with AIDS for HHV8 and HIV-1 by reverse transcriptase in situ polymerase chain reaction, as well as for Epstein-Barr virus (EBV) (EBER-1, -2) using in situ hybridization and HHV8 protein with immunohistochemistry. Four of these tumors were plasmablastic lymphomas; the final case was diffuse large B-cell lymphoma. Most of the neoplastic cells in these five lymphomas contained HHV8 RNA and protein. Further, the four plasmablastic lymphoma cases had tumor cells that contained EBV. HIV-1 RNA was not detected in the tumor cells but was noted in surrounding benign T cells. In comparison, HHV8 RNA was not detected in any of the five oral cavity lymphomas from people who did not have acquired immunosuppression nor in five lymphomas from AIDS patients that were located at a site other than the oral cavity. It is concluded that oral cavity lymphomas from people with AIDS are strongly associated with infection by HHV8 and EBV. Given the poor prognosis of oral cavity lymphomas in immunocompromised patients, therapy directed against the HHV8 and EBV infection may be of therapeutic value.
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PMID:Oral plasmablastic lymphomas in AIDS patients are associated with human herpesvirus 8. 1548 61

Deletions of chromosome 8p are a recurrent event in B-cell non-Hodgkin lymphoma (B-NHL), suggesting the presence of a tumor suppressor gene. We have characterized these deletions using comparative genomic hybridization to microarrays, fluorescence in situ hybridization (FISH) mapping, DNA sequencing, and functional studies. A minimal deleted region (MDR) of 600 kb was defined in chromosome 8p21.3, with one mantle cell lymphoma cell line (Z138) exhibiting monoallelic deletion of 650 kb. The MDR extended from bacterial artificial chromosome (BAC) clones RP11-382J24 and RP11-109B10 and included the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene loci. Sequence analysis of the individual expressed genes within the MDR and DNA sequencing of the entire MDR in Z138 did not reveal any mutation. Gene expression analysis and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) showed down-regulation of TRAIL-R1 and TRAIL-R2 receptor genes as a consistent event in B-NHL with 8p21.3 loss. Epigenetic inactivation was excluded via promoter methylation analysis. In vitro studies showed that TRAIL-induced apoptosis was dependent on TRAIL-R1 and/or -R2 dosage in most tumors. Resistance to apoptosis of cell lines with 8p21.3 deletion was reversed by restoration of TRAIL-R1 or TRAIL-R2 expression by gene transfection. Our data suggest that TRAIL-R1 and TRAIL-R2 act as dosage-dependent tumor suppressor genes whose monoallelic deletion can impair TRAIL-induced apoptosis in B-cell lymphoma.
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PMID:Characterization of 8p21.3 chromosomal deletions in B-cell lymphoma: TRAIL-R1 and TRAIL-R2 as candidate dosage-dependent tumor suppressor genes. 1605 35


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