Project description:Recently, a subset of MYC-translocation negative aggressive B-cell lymphomas resembling Burkitt lymphoma (BL) characterized by proximal gains and distal losses in the long arm of chromosome 11 has been described. In the 2016 revision of the WHO classification these MYC-translocation negative lymphomas have been introduced as new provisional entity designated “Burkitt-like lymphoma with 11q aberration” (MNBLL 11q). Here, we show a comprehensive flow-cytometry analysis of 10 MNBLL 11q cases, well characterized genetically and pathologically. Twenty-three cases of MYC-positive BL, including three cases carrying both MYC rearrangements and 11q aberration, served as controls. All MNBLL 11q were CD20+/CD10+/BCL6+/BCL2- /MUM1- /MYC+/EBV negative , presented a high proliferation rate and showed a three-year overall survival (80%) similar to BL patients, with no recurrence after the end of treatment. MNBLL 11q immunophenotype was similar to that of MYC-positive BL without and with 11q, except for less frequent CD38higher expression (10% MNBLL 11q vs 91% MYC-positive BL, p<0.001), less frequent diminished CD45 expression (90% vs 23%, p=0.001), and CD16/CD56 co-expression (60% vs 0%, p<0.001). Our findings suggest subtle but important differences in MNBLL 11q immunophenotypes and MYC-positive BLs, which could not only aid in the differential diagnosis but also in the understanding of the pathogenesis of MNBLL 11q.
2019-07-30 | GSE93002 | GEO
Project description:A recurrent 11q aberration pattern characterizes a subset of MYC-negative mature aggressive B-cell lymphomas resembling Burkitt lymphoma
Project description:In Burkitt lymphoma (BL), an aggressive germinal-center (GC) derived non-Hodgkin B-cell lymphoma characterized by MYC translocations as early transforming event, the apoptotic properties of MYC must have been overcome by pro-survival signals. Whereas activation of the pro-survival factor NFkappaB is not eminent in BL, PI3K signalling, which mediates B cell receptor associated survival signals in mature B cells, might be the cooperating event. Here we prove this hypothesis by the generation of BL in mice upon concordant expression of MYC and activation of PI3K in GC B cells. Unlike existing murine BL-like models, our tumour model fully phenocopies primary human BL and reflects the complexity of the disease with regard to histological appearance, surface marker expression, and characteristic gene expression profiles. Like in human BL, tumour monoclonality indicated a multistep pathogenesis underlining MYC and PI3K as predisposing events that invariably lead to GC-derived BL formation. In accordance, copy number alteration analysis revealed genomic regions involved in BL pathogenesis. All samples were obtained from murine lymphomas (Cgamma1-cre; R26StopFLMYC;R26StopFLP110* animals). Cells used for microarray analysis were sorted reporter positive cells. Tumour cells were compared to a matched germline DANN sample to identify acquired aberrations.
Project description:Detailed analysis of 11q aberrations consisted of duplication, terminal deletion and inversion performed by SNP/aCGH on 11 patients with BLL,11q; BL and HGBL,NOS diagnosis.
Project description:For sporadic Burkitt lymphoma (BL) few genetic lesions are known besides the pathognomonic IG-MYC translocations. Thirtynine molecularly-defined BL were analyzed with high-resolution single-nucleotide polymorphism chips for genomic imbalances and uniparental disomy (UPD). Imbalances were correlated to transcript profiling and selected miRNA analysis. Translocations affecting the MYC locus were studied by fluoresence in situ hybridization. We detected 528 copy number changes, defining 29 recurrently imbalanced regions. 518 regions of UPD were found, but these were rarely recurrent. Combined imbalance mapping and transcript profiling revealed a profound correlation between copy number and expression. Several recurrent imbalances affected the MYC pathway: The miRNA-supercluster 17-92 was frequently gained and the transcription factor E2F2 was recurrently deleted. Molecular BL lacking MYC translocations showed MYC gains. Amplifications of the polymerase iota gene were associated with increased genomic instability. The present findings suggests that UPDs play no major role in the pathogenesis of BL, whereas some genes may contribute to BL development through gene dosage effects. Amplifications of the polymerase iota gene may be functionally linked with increased genomic instability in BL. The pattern and rarity of chromosomal changes detectable even at the high resolution employed here, together with aberrations of genes regulating MYC activity, support that deregulation of the MYC pathway is the major force driving BL pathogenesis, but show that this deregulation is more complex than previously known. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from whole tissue. Copy number and LOH analysis of 500K SNP arrays was performed for 30 molecularly-defined Burkitt lymphomas. Genotyping was performed using the BRLMM-algorithm. Only a single 250k Chip was performed for nine additional Burkitts. 20 normal references (10 of those hybridized to nsp-chips) extracted from healthy blood donors, used as normals in the analysis in addition to the HapMap references provided by Affymetrix, are included in the set.
Project description:The most frequent mature aggressive B-cell lymphomas are diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL). Patients suffering from molecularly defined BL (mBL) but treated with a regimen developed for DLBCL show an unfavorable outcome compared to mBL treated with chemotherapy regimens for BL. Distinguishing BL from DLBCL by conventional histopathology is challenging in lymphomas that have features common to both diseases (aggressive B-cell lymphoma unclassifiable with features of DLBCL and BL [intermediates]). Moreover, DLBCL are a heterogeneous group of lymphomas comprising distinct molecular subtypes: the activated B-cell (ABC)-like, the germinal center B-cell-like (GCB) and the unclassifyable subtype as defined by gene expression profiling (GEP). Attempts to replace GEP with techniques applicable to formalin-fixed paraffin-embedded (FFPE) tissue led to algorithms for immunohistochemical stainings (IHS). Disappointingly, the algorithms yielded conflicting results with respect to their prognostic potential, raising concerns about their validity. Furthermore, IHS algorithms did not provide a fully resolved classification: They did not identify mBL; nor did they separate ABC from unclassified DLBCL.
Project description:The most frequent mature aggressive B-cell lymphomas are diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL). Patients suffering from molecularly defined BL (mBL) but treated with a regimen developed for DLBCL show an unfavorable outcome compared to mBL treated with chemotherapy regimens for BL. Distinguishing BL from DLBCL by conventional histopathology is challenging in lymphomas that have features common to both diseases (aggressive B-cell lymphoma unclassifiable with features of DLBCL and BL [intermediates]). Moreover, DLBCL are a heterogeneous group of lymphomas comprising distinct molecular subtypes: the activated B-cell (ABC)-like, the germinal center B-cell-like (GCB) and the unclassifyable subtype as defined by gene expression profiling (GEP). Attempts to replace GEP with techniques applicable to formalin-fixed paraffin-embedded (FFPE) tissue led to algorithms for immunohistochemical stainings (IHS). Disappointingly, the algorithms yielded conflicting results with respect to their prognostic potential, raising concerns about their validity. Furthermore, IHS algorithms did not provide a fully resolved classification: They did not identify mBL; nor did they separate ABC from unclassified DLBCL.
Project description:The most frequent mature aggressive B-cell lymphomas are diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL). Patients suffering from molecularly defined BL (mBL) but treated with a regimen developed for DLBCL show an unfavorable outcome compared to mBL treated with chemotherapy regimens for BL. Distinguishing BL from DLBCL by conventional histopathology is challenging in lymphomas that have features common to both diseases (aggressive B-cell lymphoma unclassifiable with features of DLBCL and BL [intermediates]). Moreover, DLBCL are a heterogeneous group of lymphomas comprising distinct molecular subtypes: the activated B-cell (ABC)-like, the germinal center B-cell-like (GCB) and the unclassifyable subtype as defined by gene expression profiling (GEP). Attempts to replace GEP with techniques applicable to formalin-fixed paraffin-embedded (FFPE) tissue led to algorithms for immunohistochemical stainings (IHS). Disappointingly, the algorithms yielded conflicting results with respect to their prognostic potential, raising concerns about their validity. Furthermore, IHS algorithms did not provide a fully resolved classification: They did not identify mBL; nor did they separate ABC from unclassified DLBCL. We used digital multiplexed gene expression (DMGE) with FFPE derived RNA to classify agressive B-cell lymphomas. Our assay comprised only 30 genes (10 for the detection of mBL and 20 for the detection of ABC and GCB). We chose these genes by reanalysis of the microarray data reported in a previous study. 39 samples from mature aggressive B-cell lymphomas were analyzed using DMGE (nCounter, NanoString Technologies Inc., Seattle, WA, USA) of FFPE- and fresh-frozen derived RNA. All cases were previously characterized by the Molecular Mechanisms of Malignant Lymphoma (MMML) consortium using the Affymetrix GeneChip technology (gold standard of classification).
Project description:For sporadic Burkitt lymphoma (BL) few genetic lesions are known besides the pathognomonic IG-MYC translocations. Thirtynine molecularly-defined BL were analyzed with high-resolution single-nucleotide polymorphism chips for genomic imbalances and uniparental disomy (UPD). Imbalances were correlated to transcript profiling and selected miRNA analysis. Translocations affecting the MYC locus were studied by fluoresence in situ hybridization. We detected 528 copy number changes, defining 29 recurrently imbalanced regions. 518 regions of UPD were found, but these were rarely recurrent. Combined imbalance mapping and transcript profiling revealed a profound correlation between copy number and expression. Several recurrent imbalances affected the MYC pathway: The miRNA-supercluster 17-92 was frequently gained and the transcription factor E2F2 was recurrently deleted. Molecular BL lacking MYC translocations showed MYC gains. Amplifications of the polymerase iota gene were associated with increased genomic instability. The present findings suggests that UPDs play no major role in the pathogenesis of BL, whereas some genes may contribute to BL development through gene dosage effects. Amplifications of the polymerase iota gene may be functionally linked with increased genomic instability in BL. The pattern and rarity of chromosomal changes detectable even at the high resolution employed here, together with aberrations of genes regulating MYC activity, support that deregulation of the MYC pathway is the major force driving BL pathogenesis, but show that this deregulation is more complex than previously known.
Project description:We performed genomic and transcriptomic analysis of seven cases of molecular Burkitt lymphoma (mBL) developed in immunosuppressed patients who underwent solid organ transplantation. Interestingly, three cases (43%) were MYC-translocation-negative and revealed the 11q-gain/loss aberration recently identified in 3% of mBL developed in immunocompetent hosts.1 Based on array CGH data, minimal gain and loss regions of 11q (MGR/~4Mb and MLR/~13.5Mb, respectively) were defined and integrative genomic and transcriptomic analysis identified 35 differentially expressed genes, when compared with classic BL. All 16 MGR-dysregulated genes were upregulated, including cancer related USP2, CBL and PAFAH1B2. As expected, all 19 MGL-dysregulated genes were downregulated and two of them, TBRG1 and EI24, are potential tumor suppressor genes. Interestingly, the vast majority of dysregulated 11q23-q25 genes are involved in the MYC and TP53 networks. We hypothesize that the 11q-gain/loss aberration represents a “molecular variant” of t(8q24/MYC) and affects the same pathological pathways as the MYC oncogene. Seven cases of PTLD with BL features were selected from a cohort of 174 posttransplant patients diagnosed with PTLD between 1989 and 2012 at the University Hospitals of KU Leuven (Leuven, Belgium). In addition, five classic BL cases were selected as immunocompetent controls (IC-BL). Morphologic, immunophenotypic, clinical and cytogenetic characteristics of the selected cases were reviewed.