Dataset Information

Expression of cFLIP is necessary for diffuse large B cell lymphoma pathogenesis

ABSTRACT: Diffuse large B cell lymphoma (DLBCL) is a highly heterogenous malignant disease that remains a major clinical challenge as relapsed and refractory disease is difficult to treat. Apoptosis evasion is a major feature of DLBCL. However, while the suppression of intrinsic apoptosis has long been recognized as a lymphoma-promoting event, the role of extrinsic apoptosis has remained poorly defined. Here, we demonstrated at the genetic level that expression of cFLIP, the most crucial, non-redundant inhibitor of extrinsic apoptosis, in B cells is necessary for the development of diffuse large B cell lymphoma (DLBCL) in an autochthonous murine model. Indeed, B cell-specific deletion of Cflar, the gene encoding for cFLIP, prevented lymphomagenesis mediated by oncogenic Myd88 and overexpression of BCL2. In human lymphoma cells, we showed that the absence of cFLIP sensitizes ABC- but not GCB DLBCL subtype cells to TRAIL- or LPS-induced, Caspase-8-mediated apoptosis. Furthermore, we unveiled a cell death-independent role of cFLIP in the suppression of pro-inflammatory cytokines at the transcriptional level, selectively in the ABC subtype. These results indicate that the suppression of intrinsic apoptosis can support lymphomagenesis only if extrinsic apoptosis is properly controlled. Moreover, licensing extrinsic apoptosis via cFLIP deletion can efficiently promote the death of DLBCL cells despite the suppression of the intrinsic pathway. Overall, these data provide the rationale for the development of cFLIP inhibitors for the treatment of ABC DLBCL and possibly other haematological cancers.

ORGANISM(S): Homo sapiens

PROVIDER: GSE322653 | GEO | 2026/03/15

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Constitutive activation of the anti-apoptotic NF-ÎºB signaling pathway is a hallmark of the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphomas (DLBCL) that is characterized by adverse survival. Recurrent oncogenic mutations are found in the scaffold protein CARMA1 (CARD11) that connects B-cell receptor (BCR) signaling to the canonical NF-ÎºB pathway. We asked how far additional downstream processes are activated and contribute to the oncogenic potential of DLBCL-derived CARMA1 mutants. To this end, we expressed oncogenic CARMA1 mutants in the NF-ÎºB negative DLBCL lymphoma cell line BJAB. By a proteomic approach we identified recruitment of Î²-Catenin and its destruction complex consisting of APC, AXIN1, CK1Î± and GSK3Î² to oncogenic CARMA1. Recruitment of the Î²-Catenin destruction complex was independent of CARMA1-BCL10-MALT1 (CBM) complex formation or constitutive NF-ÎºB activation and promoted the stabilization of Î²-Catenin. Elevated Î²-Catenin expression was detected in cell lines and biopsies from ABC DLBCL that rely on chronic BCR signaling. Increased Î²-Catenin amounts alone were not sufficient to induce classical WNT target gene signatures, but could augment TCF/LEF dependent transcriptional activation in response to WNT signaling. In conjunction with NF-ÎºB, Î²-Catenin enhanced expression of immune suppressive IL-10 and repressed anti-tumoral CCL3, indicating that Î²-Catenin may induce a favorable tumor microenvironment. Thus, parallel activation of NF-ÎºB and Î²-Catenin signaling by gain-of-function mutations in CARMA1 can augment WNT stimulation and is required for maintaining high expression of distinct NF-ÎºB target genes and can thereby trigger cell intrinsic and extrinsic processes that promote DLBCL lymphomagenesis. CARMA1 mutants were expressed in BJAB, an NF-ÎºB negative GCB DLBCL lymphoma cell line. Gene expression induced by GCB DLBCL derived CARMA1 L225LI mutant was compared with the empty vector (mock) control, CARMA1 WT, CARMA1 point mutant R35A and with CARMA1 double mutant R35A/L225LI.

Project description:Diffuse large B-cell lymphoma (DLBCL), the most common form of lymphoma in adulthood, comprises multiple biologically and clinically distinct subtypes including germinal center B cell-like (GCB) and activated B cell like (ABC) DLBCL. Gene expression profile studies have shown that its most aggressive subtype, ABC-DLBCL, is associated with constitutive activation of the NF-kB transcription complex. However, except for a small fraction of cases, it remains unclear whether NF-kB activation in these tumors represents an intrinsic program of the tumor cell of origin or a pathogenetic event. Here we show that >50% of ABC-DLBCL and a smaller fraction of GCB-DLBCL carry somatic mutations at multiple genes, including negative (TNFAIP3/A20) and positive (CARD11, TRAF2, TRAF5, MAP3K7/TAK1 and TNFRSF11A/RANK) regulators of NF-kB. Of these, the A20 gene, which encodes for a ubiquitin-modifying enzyme involved in termination of NF-kB responses, is the most commonly affected one, with ~30% of the patients displaying biallelic inactivation by mutations and/or deletions, suggesting a tumor suppressor role. Less frequently, missense mutations of TRAF2 and CARD11 produce molecules with significantly enhanced ability to activate NF-kB. Thus, our results demonstrate that NF-kB activation in DLBCL is caused by genetic lesions affecting multiple genes, whose loss or activation may promote lymphomagenesis by leading to abnormally prolonged NF-kB responses. We show that most ABC-DLBCL and a smaller fraction of GCB-DLBCL display genetic lesions affecting multiple NFkB pathway genes, with A20 representing the most frequently mutated gene Experiment Overall Design: DLBCL biopsies from 73 patients were collected from the archives of the Departments of Pathology at Columbia University and Weill Cornell Medical College. Total RNA was extracted from frozen tumor biopsies and processed according to Affymetrix standard protocols. Purified tonsillar geminal center cells (centroblasts and centrocytes, 5 samples each from different individuals) were purified by magnetic cell separation as described in Klein et al, PNAS 2003.

Dataset Information

Expression of cFLIP is necessary for diffuse large B cell lymphoma pathogenesis

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets