Project description:Multiple types of B-cell lymphoma respond clinically to BTK inhibition, reflecting their dependence on B-cell receptor signaling. The germinal center B-cell subtype of diffuse large B-cell lymphoma resists BTK inhibition, but we found that B-cell receptor elimination in cell lines of this lymphoma type reduced their size and proliferation. Their B-cell receptor signals in a “tonic”, antigen-independent manner, requiring SYK, CD19, and phosphorylation of a specific tyrosine residue in the CD79A immunoreceptor tyrosine-based activation motif domain. The effect of B-cell receptor elimination or inhibition in these lines is proportional to their B-cell receptor surface density and its relative contribution to AKT activity, on which these lines uniformly depend, and is rescued by spontaneous or induced loss of PTEN protein. Biomarker-guided targeting of tonic B-cell receptor signaling may improve treatment of germinal center B-cell lymphoma.
Project description:B-cell receptor (BCR) signaling promotes the survival of malignant B cells, such as Burkitt’s lymphoma (BL) and the activated B-cell-like subtype of diffuse large B cell lymphoma (ABC-DLBCL). In contrast to ABC DLBCL, where malignant cells require chronic activation of the BCR for their survival, BL cells are dependent on tonic BCR signaling that is antigen-independent. Elucidation and systematic comparison of tonic and activated BCR signaling led to the identification of novel signaling effectors, among them ACTN4 and ARFGEF2, which were identified as regulators of BL cell survival. As tonic and activated BCR signaling are relevant for important aspects of B cell biology, our study helps in gaining an understanding of BCR-induced processes not only in malignant but potentially also physiological settings.
Project description:Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma, including two main molecular subtypes termed activated B cell-like (ABC) and germinal center B cell-like (GCB). ABC DLBCL is less curable and identification of new molecular targets is needed for the development of effective therapeutic agents. Here, we focused on EGR1, a transcription factor that is regulated by the B cell receptor and JAK1/STAT3 signaling pathway in ABC DLBCL. ChIP-Seq and RNA-Seq analyses revealed that gene regulation by EGR1 in ABC DLBCL accentuates multiple oncogenic pathways, including MYC and E2F, while dampening the lethal type I IFN pathway.
Project description:Diffuse large B-cell lymphoma (DLBCL) is currently divided into three main molecular subtypes, defined by gene expression profiling (GEP): Germinal Center B-cell like (GCB), Activated B-Cell like (ABC), and Primary Mediastinal B-cell Lymphoma (PMBL). DLBCL subtypes were determined according to patients' gene expression profiles.
Project description:The survival of patients with diffuse large-B-cell lymphoma after chemotherapy is influenced by molecular features of the tumors. We used the gene-expression profiles of these lymphomas to develop a molecular predictor of survival. METHODS: Biopsy samples of diffuse large-B-cell lymphoma from 240 patients were examined for gene expression with the use of DNA microarrays and analyzed for genomic abnormalities. Subgroups with distinctive gene-expression profiles were defined on the basis of hierarchical clustering. A molecular predictor of risk was constructed with the use of genes with expression patterns that were associated with survival in a preliminary group of 160 patients and was then tested in a validation group of 80 patients. The accuracy of this predictor was compared with that of the international prognostic index. RESULTS: Three gene-expression subgroups--germinal-center B-cell-like, activated B-cell-like, and type 3 diffuse large-B-cell lymphoma--were identified. Two common oncogenic events in diffuse large-B-cell lymphoma, bcl-2 translocation and c-rel amplification, were detected only in the germinal-center B-cell-like subgroup. Patients in this subgroup had the highest five-year survival rate. To identify other molecular determinants of outcome, we searched for individual genes with expression patterns that correlated with survival in the preliminary group of patients. Most of these genes fell within four gene-expression signatures characteristic of germinal-center B cells, proliferating cells, reactive stromal and immune cells in the lymph node, or major-histocompatibility-complex class II complex. We used 17 genes to construct a predictor of overall survival after chemotherapy. This gene-based predictor and the international prognostic index were independent prognostic indicators.
Project description:IRF8, a transcriptional factor, has the heightened expression in germinal center(GC) B cell and GC-origin B cell lymphoma. To identify IRF8 direct targets in GC B cells, ChIP-chip ananlysis was done in three different GC-origin diffuse large B cell lymphoma cell lines. IRF8-negative cell lines, MPC11, was also used as a negatvie control.
Project description:IRF8, a transcriptional factor, has the heightened expression in germinal center(GC) B cell and GC-origin B cell lymphoma. To identify IRF8 direct targets in GC B cells, ChIP-chip ananlysis was done in three different GC-origin diffuse large B cell lymphoma cell lines. IRF8-negative cell lines, MMS1, was also used as a negatvie control.
Project description:Germinal center (GC) derived B-lymphomas (GCDBL) are concomitantly generated with high-affinity B cells during humoral immune response. Among GCDBLs are Burkitt’s lymphoma (BL), diffuse large B cell lymphoma (DLBCL), and Multiple myeloma (MM), which originate from distinct GC compartments. Whether specific transcription factors work in GCs to suppress the GCBLD is elusive.
Project description:Germinal center (GC) derived B-lymphomas (GCDBL) are concomitantly generated with high-affinity B cells during humoral immune response. Among GCDBLs are Burkitt’s lymphoma (BL), diffuse large B cell lymphoma (DLBCL), and Multiple myeloma (MM), which originate from distinct GC compartments. Whether specific transcription factors work in GCs to suppress the GCBLD is elusive.
Project description:PU.1, a transcriptional factor, is expressed in wide range of B cells from early to mature stage. To identify PU.1 direct targets in germinal center B cells, ChIP-chip ananlysis was done in three different GC-origin diffuse large B cell lymphoma cell lines.
