Publications

3 Publications matching the given criteria: (Clear all filters)

Abstract (Expand)

Chromosomal translocations involving an immunoglobulin (IG) locus and a proto-oncogene play a major role in diffuse large B-cell lymphoma (DLBCL) pathogenesis. Recurrent IG translocation partners in DLBCL are the BCL6, BCL2, and MYC genes, but other rare translocation partners are also known. We studied 20 DLBCL with fluorescence in situ hybridization-based evidence for IG heavy chain (IGH) locus-associated translocations not involving BCL6, BCL2, MALT1, or MYC by long distance inverse PCR to identify the translocation partners. Moreover, we studied eight DLBCL with MYC translocations not involving IG or known non-IG loci as translocation partner to search for novel MYC translocations. We identified three novel IGH-associated translocations. Chromosomal breakpoints involved the IMMP2L gene in 7q31, the BCAS2 gene in 1p13, and the PVRL2 gene in 19q13. The latter gene, which is recurrently translocated in T-cell lymphomas, is significantly higher expressed in the biopsy with the translocation compared to cases without this genetic aberration, indicating a pathogenetic role of PVRL2 also in DLBCL. In one case with a MYC break we obtained a novel MYC-SOCS1 translocation representing an unusual translocation of a proto-oncogene with a tumor suppressor gene. Indeed, we demonstrate that the oncogene was deregulated and the tumor suppressor gene inactivated. As both genes undergo aberrant somatic hypermutation in the region of the chromosomal breakpoints, this translocation likely happened as a byproduct of the hypermutation process. Overall, our study suggests that chromosomal translocations in DLBCL are more heterogeneous than previously known. (c) 2016 Wiley Periodicals, Inc.

Authors: C. Otto, R. Scholtysik, R. Schmitz, M. Kreuz, C. Becher, M. Hummel, A. Rosenwald, L. Trumper, W. Klapper, R. Siebert, R. Kuppers

Date Published: 30th Jun 2016

Publication Type: Journal article

Human Diseases: diffuse large B-cell lymphoma

Abstract (Expand)

The pathogenesis of diffuse large B-cell lymphomas (DLBCL) is only partly understood. We analyzed 148 DLBCL by single nucleotide polymorphism (SNP)-chips to characterize genomic imbalances. Seventy-nine cases were of the germinal center B-cell like (GCB) type of DLBCL, 49 of the activated B-cell like (ABC) subtype and 20 were unclassified DLBCL. Twenty-four regions of recurrent genomic gains and 38 regions of recurrent genomic losses were identified over the whole cohort, with a median of 25 imbalances per case for ABC-DLBCL and 19 per case for GCB-DLBCL. Several recurrent copy number changes showed differential frequencies in the GCB- and ABC-DLBCL subgroups, including gains of HDAC7A predominantly in GCB-DLBCL (38% of cases) and losses of BACH2 and CASP8AP2 predominantly in ABC-DLBCL (35%), hinting at disparate pathogenetic mechanisms in these entities. Correlating gene expression and copy number revealed a strong gene dosage effect in all tumors, with 34% of probesets showing a concordant expression change in affected regions. Two new potential tumor suppressor genes emerging from the analysis, CASP3 and IL5RA, were sequenced in ten and 16 candidate cases, respectively. However, no mutations were found, pointing to a potential haploinsufficiency effect of these genes, considering their reduced expression in cases with deletions. Our study thus describes differences and similarities in the landscape of genomic aberrations in the DLBCL subgroups in a large collection of cases, confirming already known targets, but also discovering novel copy number changes with possible pathogenetic relevance.

Authors: R. Scholtysik, M. Kreuz, M. Hummel, M. Rosolowski, M. Szczepanowski, W. Klapper, M. Loeffler, L. Trumper, R. Siebert, R. Kuppers

Date Published: 1st Mar 2015

Publication Type: Not specified

Human Diseases: diffuse large B-cell lymphoma

Abstract (Expand)

Chromosomal translocations affecting the MYC oncogene are the biological hallmark of Burkitt lymphomas but also occur in a subset of other mature B-cell lymphomas. If accompanied by a chromosomal break targeting the BCL2 and/or BCL6 oncogene these MYC translocation-positive (MYC(+)) lymphomas are called double-hit lymphomas, otherwise the term single-hit lymphomas is applied. In order to characterize the biological features of these MYC(+) lymphomas other than Burkitt lymphoma we explored, after exclusion of molecular Burkitt lymphoma as defined by gene expression profiling, the molecular, pathological and clinical aspects of 80 MYC-translocation-positive lymphomas (31 single-hit, 46 double-hit and 3 MYC(+)-lymphomas with unknown BCL6 status). Comparison of single-hit and double-hit lymphomas revealed no difference in MYC partner (IG/non-IG), genomic complexity, MYC expression or gene expression profile. Double-hit lymphomas more frequently showed a germinal center B-cell-like gene expression profile and had higher IGH and MYC mutation frequencies. Gene expression profiling revealed 130 differentially expressed genes between BCL6(+)/MYC(+) and BCL2(+)/MYC(+) double-hit lymphomas. BCL2(+)/MYC(+) double-hit lymphomas more frequently showed a germinal center B-like gene expression profile. Analysis of all lymphomas according to MYC partner (IG/non-IG) revealed no substantial differences. In this series of lymphomas, in which immunochemotherapy was administered in only a minority of cases, single-hit and double-hit lymphomas had a similar poor outcome in contrast to the outcome of molecular Burkitt lymphoma and lymphomas without the MYC break. Our data suggest that, after excluding molecular Burkitt lymphoma and pediatric cases, MYC(+) lymphomas are biologically quite homogeneous with single-hit and double-hit lymphomas as well as IG-MYC and non-IG-MYC(+) lymphomas sharing various molecular characteristics.

Authors: S. M. Aukema, M. Kreuz, C. W. Kohler, M. Rosolowski, D. Hasenclever, M. Hummel, R. Kuppers, D. Lenze, G. Ott, C. Pott, J. Richter, A. Rosenwald, M. Szczepanowski, C. Schwaenen, H. Stein, H. Trautmann, S. Wessendorf, L. Trumper, M. Loeffler, R. Spang, P. M. Kluin, W. Klapper, R. Siebert

Date Published: 2nd Nov 2013

Publication Type: Not specified

Human Diseases: non-Hodgkin lymphoma, diffuse large B-cell lymphoma

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