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  • 1
    ISSN: 1569-8041
    Keywords: AIDS ; bcl-6 ; genetic lesion ; lymphoma ; oncogene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Non-Hodgkin's lymphoma (NHL) represents a major complication of AIDS. Systemic AIDS-related NHLs (AIDS-NHLs) derive from B cells and are classified into four distinct groups, including small noncleaved-cell lymphoma (SNCCL), diffuse large-cell lymphoma (DLCL), anaplastic large-cell lymphoma (ALCL), and body-cavity-based lymphoma (BCBL). The molecular pathogenesis of AIDS-NHL is characterized by the association of specific genetic lesions with distinct AIDS-NHL categories. Genetic lesions of AIDS-NHL involve proto-oncogenes (c-myc, Ras), tumor suppressor loci (p53,6q), and viral infection (Epstein–Barr virus, human herpesvirus type8). Design: The aim of this work was to define the involvement of the bcl-6gene in AIDS-related lymphomagenesis by investigating the distribution ofbcl-6 structural alterations throughout the pathologic spectrum of AIDS-NHL. Both gross rearrangements and mutations in the 5′ non coding regions of the gene were investigated. Results: Gross rearrangements of bcl-6 are confined to a fraction of AIDS-DLCL cases among AIDS-NHLs. Conversely, mutations of the 5′noncoding regions of bcl-6 are detected in a large proportion of AIDS-SNCCLs, AIDS-DLCLs and AIDS-ALCLs independent of the concomitant presence of bcl-6 rearrangements. Conclusions: Mutations of the 5′ noncoding regions of bcl-6 represent the most frequent genetic lesion presently detectable among systemic AIDS-NHLs. The frequency of these mutations and their location in the proximity of bcl-6 regulatory regions suggest that they may play a rolein AIDS-related lymphomagenesis.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1569-8041
    Keywords: bcl-6 ; c-myc ; EBV ; p53 ; pathogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Burkitt's lymphoma is a B-cell neoplasm characterized by a chromosomal translocation involving the c-myc gene. BL may carry, besides the c-myc translocation, several other lesions including a) mutations in c-myc, b) mutations in bcl-6, c) mutations in p53 and d) EBV genomes. In this report we describe a unique study of the timing of these genetic lesions during the evolution and progression of Burkitt's lymphoma. Materials and methods: From each of two patients with Burkitt's lymphoma, we established three different cell lines – from different sites or at different times in the clinical course of the disease (diagnosis and relapse). Chromosomal aberrations were analyzed by karyotyping and the presence of molecular lesions determined by Southern blot, PCR, SSCP and sequence analyses. Results: In each patient all the clones carry identical c-myc translocations, identical bcl-6 status (wild type or mutant) and the same productive VDJ rearrangement. However, within each individual patient, we could demonstrate the presence of intraclonal variation with respect to EBV, p53 mutations and c-myc mutations. Conclusions: c-myc translocation and bcl-6 mutations appear to be early events, mutations in the coding region of c-myc occur early but are an ongoing event, while mutations in the p53 gene seem to occur later. Discrete clonal bands reflecting independent EBV infection were observed in the cell lines from one HIV-associated Burkitt's lymphoma, suggesting the possibility that EBV infection may occur as a late event, at least in some HIV associated lymphomas.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1569-8041
    Keywords: AIDS ; bcl-6 ; genetic lesion ; lymphoma ; oncogene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Non-Hodgkin's lymphoma (NHL) represents a major complicationof AIDS. Systemic AIDS-related NHLs (AIDS-NHLs) derive from B cells and areclassified into four distinct groups, including small noncleaved-celllymphoma (SNCCL), diffuse large-cell lymphoma (DLCL), anaplastic large-celllymphoma (ALCL), and body-cavity-based lymphoma (BCBL). The molecularpathogenesis of AIDS-NHL is characterized by the association of specificgenetic lesions with distinct AIDS-NHL categories. Genetic lesions ofAIDS-NHL involve proto-oncogenes (c-myc, Ras), tumor suppressor loci (p53,6q), and viral infection (Epstein–Barr virus, human herpesvirus type8). Design: The aim of this work was to define the involvement of the bcl-6gene in AIDS-related lymphomagenesis by investigating the distribution ofbcl-6 structural alterations throughout the pathologic spectrum of AIDS-NHL.Both gross rearrangements and mutations in the 5′ noncoding regions ofthe gene were investigated. Results: Gross rearrangements of bcl-6 are confined to a fraction ofAIDS-DLCL cases among AIDS-NHLs. Conversely, mutations of the 5′noncoding regions of bcl-6 are detected in a large proportion ofAIDS-SNCCLs, AIDS-DLCLs and AIDS-ALCLs independent of the concomitantpresence of bcl-6 rearrangements. Conclusions: Mutations of the 5′ noncoding regions of bcl-6 represent the most frequent genetic lesion presently detectable amongsystemic AIDS-NHLs. The frequency of these mutations and their location in theproximity of bcl-6 regulatory regions suggest that they may play a rolein AIDS-related lymphomagenesis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1569-8041
    Keywords: B-DLCL ; clinical correlations ; genetic lesions ; outcome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: B-diffuse large-cell lymphomas (DLCL) have been associated with some molecular lesions, but the role of such lesions as prognostic markers is still controversial. This report concerns an investigation of the frequency and clinical correlation of bcl-6, bcl-2, c-myc rearrangements and 6(q) deletions in B-DLCL. Patients and methods: The presence of these genetic lesions was analyzed in samples of lymph nodes or bone marrow collected at diagnosis in 71 patients with B-DLCL, all treated with an antracycline-containing chemotherapy regimen. Results: Rearrangement of bcl-6 was found in 11 patients (15%), rearranged bcl-2 in 12 (17%), 6(q) deletions in 10 patients (14%) and c-myc rearrangement in four (6%). Patients with rearranged bcl-6 tended to have a more aggressive disease than patients with germ-line bcl-6 (intermediate–high/high risk according to IPI criteria: 73% vs. 43%), but there were no differences in three-year survival rates (62% vs. 42%) between the two groups. The numbers of involved extranodal sites were similar in patients with rearranged and those with germ-line bcl-6. Patients with bcl-2 rearrangement appeared to have a less aggressive disease than those with germ-line bcl-2 (low/low–intermediate risk 75% vs. 47%) and a slightly better three-year survival rate (70% vs. 41%) but again the difference was not significant. Both groups with or without 6(q) deletion had similar clinical characteristics and outcomes. The four patients with c-myc rearrangement had aggressive disease and did poorly. Conclusions: The analysis of molecular lesions in B-DLCL may be useful for a better diagnostic definition; however, in this study we were unable to show that the evaluated genetic lesions had a significant impact on clinical outcome.
    Type of Medium: Electronic Resource
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