BHLHE41, a transcriptional repressor involved in physiological processes and tumor development

International audienceBHLHE41 is a nuclear transcriptional repressor that belongs to the basic helix-loop-helix protein superfamily. BHLHE41 expression tends to be restricted to specific tissues and is regulated by environmental cues and biological events. BHLHE41 homodimerizes or heterodimerizes with various partners, influencing its transcription factor function. BHLHE41 is involved in the regulation of many physiological processes implicated in tissue/organ homeostasis, such as myogenesis, adipogenesis, circadian rhythms and DNA repair. At cellular level, BHLHE41 is involved in the regulation of mesenchymal stem cell properties, tissue-specific macrophage functions and lymphoid lineage physiology. In several cancer types, BHLHE41 modulates the expression of different transcriptional programs influencing cell cycle control, apoptosis, invasiveness, epithelial to mesenchymal transition and hypoxia response in the tumor environment. Depending on the cancer cell type, BHLHE41 can act as a tumor suppressor or an oncogene, and could be a target for innovative therapies. This review summarizes the available knowledge on BHLHE41 structure, biological functions, regulation and potential partners, as well as its role in physiological processes, and its implication in major cancer steps

Plasmablasts derive from CD23-negative activated B cells after the extinction of IL-4/STAT6 signaling and IRF4 induction

International audienceThe terminal differentiation of B cells into antibody-secreting cells (ASCs) is a critical component of adaptive immune responses. However, it is a very sensitive process, and dysfunctions lead to a variety of lymphoproliferative neoplasias including germinal center-derived lymphomas. To better characterize the late genomic events that drive the ASC differentiation of human primary naive B cells, we used our in vitro differentiation system and a combination of RNA sequencing and Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC sequencing). We discovered 2 mechanisms that drive human terminal B-cell differentiation. First, after an initial response to interleukin-4 (IL-4), cells that were committed to an ASC fate downregulated the CD23 marker and IL-4 signaling, whereas cells that maintained IL-4 signaling did not differentiate. Second, human CD23- cells also increased IRF4 protein to levels required for ASC differentiation, but they did that independently of the ubiquitin-mediated degradation process previously described in mice. Finally, we showed that CD23- cells carried the imprint of their previous activated B-cell status, were precursors of plasmablasts, and had a phenotype similar to that of in vivo preplasmablasts. Altogether, our results provide an unprecedented genomic characterization of the fate decision between activated B cells and plasmablasts, which provides new insights into the pathological mechanisms that drive lymphoma biology

Assessment of Circulating Tumor DNA in Newly Diagnosed DLBCL Patients Randomly Treated By R-CHOP or R-High Dose Chemotherapy Plus Autologous Stem Cell Support

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Research Article Combined Stimulation with the Tumor Necrosis Factor α and the Epidermal Growth Factor Promotes the Proliferation of Hepatocytes in Rat Liver Cultured Slices

Copyright © 2012 Francis Finot et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The culture liver slices are mainly used to investigate drug metabolism and xenobiotic-mediated liver injuries while apoptosis and proliferation remain unexplored in this culture model. Here, we show a transient increase in LDH release and caspase activities indicating an ischemic injury during the slicing procedure. Then, caspase activities decrease and remain low in cultured slices demonstrating a low level of apoptosis. The slicing procedure is also associated with the G0/G1 transition of hepatocytes demonstrated by the activation of stress and proliferation signalling pathways including the ERK1/2 and JNK1/2/3 MAPKinases and the transient upregulation of c-fos. The cells further progress up to mid-G1 phase as indicated by the sequential induction of c-myc and p53 mRNA levels after the slicing procedure and at 24 h of culture, respectively. The stimulation by epidermal growth factor induces the ERK1/2 phosphorylation but fails to activate expression of late G1 and S phase markers such as cyclin D1 and Cdk1 indicating that hepatocytes are arrested in mid-G1 phase of the cell cycle. However, we found that combined stimulatio

Pan-HDAC Inhibitors May Restore PRDM1 Expression in Follicular Lymphoma

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Linking the KIR phenotype with STAT3 and TET2 mutations to identify chronic lymphoproliferative disorders of NK cells

International audienceDistinguishing chronic lymphoproliferative disorders of NK cells (CLPD-NK) from reactive NK-cell expansion is challenging. We assessed the value of killer immunoglobulin-like receptor(KIR) phenotyping and targeted high-throughput sequencing in a cohort of 114 consecutive patients with NK cell proliferation, retrospectively assigned to a CLPD-NK group (n = 46) and a reactive NK group (n = 68). We then developed an NK-cell clonality score combining flow cytometry and molecular profiling with a positive predictive value of 93%. STAT3 and TET2 mutations were respectively identified in 27% and 34% of the patients with CLPD-NK, constituting a new diagnostic hallmark for this disease. TET2-mutated CLPD-NK preferentially exhibited a CD16low phenotype, more frequently displayed a lower platelet count, and was associated with other hematologic malignancies such as myelodysplasia. To explore the mutational clonal hierarchy of CLPD-NK, we performed whole-exome sequencing of sorted, myeloid, T, and NK cells and found that TET2 mutations were shared by myeloid and NK cells in 3 of 4 cases. Thus, we hypothesized that TET2 alterations occur in early hematopoietic progenitors which could explain a potential link between CLPD-NK and myeloid malignancies. Finally, we analyzed the transcriptome by RNA sequencing of 7 CLPD-NK and evidenced 2 groups of patients. The first group displayed STAT3 mutations or SOCS3 methylation and overexpressed STAT3 target genes. The second group, including 2 TET2-mutated cases, significantly underexpressed genes known to be downregulated in angioimmunoblastic T-cell lymphoma. Our results provide new insights into the pathogenesis of NK-cell proliferative disorders and, potentially, new therapeutic opportunities

Recurrent somatic mutations in diffuse large B cell lymphoma assessed by high throughput targeted sequencing highlight molecular subtypes’ genetic divergence: a LYSA study

International audienceIntroduction: Gene expression profiling (GEP) has identified three main subtypes of diffuse large B cell lymphoma (DLBCL): germinal centre B‐cell like (GCB), activated B‐cell like (ABC) and primary mediastinal B‐cell lymphoma (PMBL). Although next generation sequencing (NGS) has enabled a more detailed genomic characterization of DLBCL, the mutation patterns observed in different studies have been heterogeneous, highlighting the need for a consensus gene panel. Furthermore, the prognostic value of these mutations has yet to be evaluated in prospective clinical trials. Methods: A Lymphopanel designed to identify mutations in 34 genes important for lymphomagenesis was used to sequence tumour DNA of 216 patients with de novo DLBCL in prospective, multicentric and randomized LNH‐03B clinical trials led by the Groupe d'Etude du Lymphome Adulte (GELA), using the Ion PGM™ system. GEP identified 81 GCB, 81 ABC, 32 unclassified and 22 PMBL samples. Results: The Lymphopanel was informative for 96% of patients: 13975 variants were identified with a median sequencing depth of 225x, and 1075 (7.7%) were validated after filtering for variant quality, SNPs and functional relevance. The mean mutation rate per megabase was 56.7, and PMBL subtype was significantly more mutated than the other subtypes (p = 7.4 × 10e−5). We confirmed that the ABC subtype is dominated by NFkB pathway mutations (46% of variants), the GCB subtype is dominated by epigenetic pathway mutations (34% of variants) and the PMBL subtype is frequently mutated in JAK‐STAT and immunity pathways (respectively 27% and 22% of variants). The Lymphopanel confirmed subtype‐enriched mutations such as MYD88, PIM1, CD79B and IRF4 variants among ABC, BCL2, CREBBP, EZH2, MEF2B and TNFRSF14 variants among GCB and SOCS1, STAT6 and TNFAIP3 variants among PMBL. The immunity pathway seems to play a crucial role in PMBL, with respectively 59%, 36% and 45% of patients presenting mutations in B2M, CD58 and CIITA. These mutations mostly lead to truncated proteins, suggesting a predilection for immune system escape in PMBL. ITPKB, MFHAS1 and XPO1 mutations, whose roles in lymphomagenesis are unclear, were heavily weighted toward PMBL and presented mutations in respectively 40.9%, 27.3% and 31.8% of PMBL patients. XPO1 mutations especially were almost exclusively PMBL specific. Furthermore, clinical correlations were found for certain gene mutations among the total cohort, notably with age (B2M, CD79B, CIITA, KMT2D, MYD88, SOCS1, STAT6, ITPKB and XPO1), Ann Arbor stage (B2M) and IPI (B2M and STAT6). TNFAIP3 mutations in ABC patients were associated with a less favourable OS (FDR < 10e − 3) and PFS (FDR = 0.014). Conclusion: This large, prospective study demonstrates the contribution of NGS with a consensus gene panel to the goal of precision therapy in DLBCL, enabling the identification of recurrent mutations with clinical, therapeutic and prognostic impact

The negative influence of baseline cell-free DNA on long-term survival in DLBCL depends on frontline treatment intensity

International audiencePurpose - This study aims to investigate the relationship between the intensity of the initial treatment given to patients with de novo diffuse large B-cell lymphoma (DLBCL) and the impact of their baseline cell-free DNA (cfDNA) levels on their long-term survival. Experimental design - The GOELAMS 075 randomized clinical trial compared rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) with high-dose R-chemotherapy plus autologous stem cell transplantation (R-HDT) for patients aged ≤60. An interim PET assessment was used to refer patients for salvage therapy. With a median follow-up of more than 5.8 years, we analyzed the effects of the treatment arm, salvage therapy, and cfDNA level at diagnosis on overall survival (OS). Results - In a representative group of 123 patients, a high cfDNA concentration (>55 ng/mL) at diagnosis was associated with poor clinical prognostic factors and constituted a prognostic marker, independently of the age-adjusted International Prognostic Index. A cfDNA level above a threshold value of 55 ng/mL at diagnosis was associated with significantly worse OS. In an intention-to-treat analysis, high-cfDNA R-CHOP patients (but not high-cfDNA R-HDT patients) had worse OS [HR (95% confidence interval), 3.99 (1.98-10.74); P = 0.006]. In patients with high cfDNA levels, salvage therapy and transplantation were associated with a significantly higher OS rate. Among 50 patients with complete response 6 months after the end of treatment, for 11 of 24 R-CHOP patients, the cfDNA did not fall back to normal values. Conclusions - In this randomized clinical trial, intensive regimens mitigated the negative influence of high cfDNA levels in de novo DLBCL, relative to R-CHOP

A Molecular Classifier Increased the Accuracy of Lymphoma Diagnosis By Expert Pathologists in the Diffuse Large B-Cell Lymphoma Gained Trial from the Lysa

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