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.
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.
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 M-bM-^@M-^\molecular variantM-bM-^@M-^] 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.
Project description:Burkitt lymphoma (BL) is the most frequent B-cell lymphoma in pediatric patients. While most patients are currently cured, a fraction of them are resistant to therapy. In order to investigate BL heterogeneity and the features distinguishing the non-responders (NR) to therapy, we analyzed pediatric EBV-negative BL specimens collected at diagnosis by single-cell (sc)-transcriptomics. Analysis of the non-tumor component revealed a predominance of immune cell infiltrates and a small representation of fibroblasts that was enriched in NR. Tumor cells displayed patient-specific features, as well as subpopulations that were common to most patients and expressed transcripts related to cell cycle, signaling pathways and cell-of-origin signatures.
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:Burkitt lymphoma (BL) can often be cured by intensive chemotherapy, but the toxicity of such therapy precludes its use in the elderly and in patients with endemic BL (eBL) in developing countries, necessitating new strategies. The normal germinal center B cell is the presumed cell of origin for both BL and diffuse large B cell lymphoma (DLBCL), yet gene expression analysis suggests that these malignancies may utilize different oncogenic pathways. BL is subdivided into a sporadic subtype (sBL) that is diagnosed in developed countries, the EBV-associated eBL subtype, and an HIV-associated subtype (hivBL), but it is unclear whether these subtypes employ similar or divergent oncogenic mechanisms. Here we used high throughput RNA sequencing and RNA interference screening to discover essential regulatory pathways that cooperate with MYC, the defining oncogene of this cancer. In 70% of sBL cases, mutations affecting the transcription factor TCF3 (E2A) or its negative regulator ID3 fostered TCF3 dependency. TCF3 activated the pro-survival PI(3) kinase pathway in BL, in part by augmenting tonic B cell receptor signaling. In 38% of sBL cases, oncogenic CCND3 mutations produced highly stable cyclin D3 isoforms that drive cell cycle progression. These findings suggest opportunities to improve therapy for patients with BL.
Project description:Overall, the genetic profile of aggressive B-cell NHL in CAYA in the spectrum of BL and DLBCL is heterogeneous. MYC-R cases mostly displayed a molecular profile close to BL regardless of their morphology, whereas MYC-non-R had a more heterogeneous genetic landscape resembling DLBCL.
Project description:Overall, the genetic profile of aggressive B-cell NHL in CAYA in the spectrum of BL and DLBCL is heterogeneous. MYC-R cases mostly displayed a molecular profile close to BL regardless of their morphology, whereas MYC-non-R had a more heterogeneous genetic landscape resembling DLBCL.