Epstein-Barr virus–positive (EBV+) diffuse large B-cell lymphomas (DLBCLs) express high levels of programmed death ligand 1 (PD-L1) and PD-L2. MicroRNA (miR) regulation is an important mechanism for ...the fine-tuning of gene expression via 3′-untranslated region (3′UTR) targeting, and we have previously demonstrated strong EBV miR expression in EBV+ DLBCL. Whereas the EBV latent membrane protein-1 (LMP1) is known to induce PD-L1/L2, a potential counterregulatory role of EBV miR in the fine-tuning of PD-L1/L2 expression remains to be established. To examine this, a novel in vitro model of EBV+ DLBCL was developed, using the viral strain EBV WIL, which unlike common laboratory strains retains intact noncoding regions where several EBV miRs reside. This enabled interrogation of the relationship among EBV latency genes, cell of origin (COO), PD-L1, PD-L2, and EBV miRs. The model successfully recapitulated the full spectrum of B-cell differentiation, with 4 discrete COO phases: early and late germinal center B cells (GCBs) and early and late activated B cells (ABCs). Interestingly, PD-L1/L2 levels increased markedly during transition from late GCB to early ABC phase, after LMP1 upregulation. EBV miR–BamHI fragment H rightward open reading frame 1 (BHRF1)–2-5p clustered apart from other EBV miRs, rising during late GCB phase. Bioinformatic prediction, together with functional validation, confirmed EBV miR-BHRF1-2-5p bound to PD-L1 and PD-L2 3′UTRs to reduce PD-L1/L2 surface protein expression. Results indicate a novel mechanism by which EBV miR-BHRF1-2-5p plays a context-dependent counterregulatory role to fine-tune the expression of the LMP1-driven amplification of these inhibitory checkpoint ligands. Further identification of immune checkpoint–targeting miRs may enable potential novel RNA-based therapies to emerge.
•EBV miR-BHRF1-2-5p fine-tunes the LMP1-driven amplification of the immune checkpoint ligands PD-L1 and PD-L2.•Further identification of immune checkpoint–targeting miRs may enable potential novel RNA-based therapies to emerge.
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The pathogenesis of primary mediastinal large B-cell lymphoma (PMBCL) is incompletely understood. Recently, specific genotypic and phenotypic features have been linked to tumor cell immune escape ...mechanisms in PMBCL. We studied 571 B-cell lymphomas with a focus on PMBCL. Using fluorescence in situ hybridization here, we report that the programmed death ligand (PDL) locus (9p24.1) is frequently and specifically rearranged in PMBCL (20%) as compared with diffuse large B-cell lymphoma, follicular lymphoma, and Hodgkin lymphoma. Rearrangement was significantly correlated with overexpression of PDL transcripts. Utilizing high-throughput sequencing techniques, we characterized novel translocations and chimeric fusion transcripts involving PDLs at base-pair resolution. Our data suggest that recurrent genomic rearrangement events underlie an immune privilege phenotype in a subset of B-cell lymphomas.
•Programmed death ligands 1 and 2 are rearranged at a frequency of 20% in PMBCL.
Mantle cell lymphoma (MCL), an aggressive subtype of non-Hodgkin lymphoma, is characterized by the hallmark translocation t(11;14)(q13;q32) and the resulting overexpression of cyclin D1 (CCND1). Our ...current knowledge of this disease encompasses frequent secondary cytogenetic aberrations and the recurrent mutation of a handful of genes, such as TP53, ATM, and CCND1. However, these findings insufficiently explain the biologic underpinnings of MCL. Here, we performed whole transcriptome sequencing on a discovery cohort of 18 primary tissue MCL samples and 2 cell lines. We found recurrent mutations in NOTCH1, a finding that we confirmed in an extension cohort of 108 clinical samples and 8 cell lines. In total, 12% of clinical samples and 20% of cell lines harbored somatic NOTCH1 coding sequence mutations that clustered in the PEST domain and predominantly consisted of truncating mutations or small frame-shifting indels. NOTCH1 mutations were associated with poor overall survival (P = .003). Furthermore, we showed that inhibition of the NOTCH pathway reduced proliferation and induced apoptosis in 2 MCL cell lines. In summary, we have identified recurrent NOTCH1 mutations that provide the preclinical rationale for therapeutic inhibition of the NOTCH pathway in a subset of patients with MCL.
Classical Hodgkin lymphoma and primary mediastinal B cell lymphoma (PMBCL) are related lymphomas sharing pathological, molecular and clinical characteristics. Here we discovered by whole-genome and ...whole-transcriptome sequencing recurrent somatic coding-sequence mutations in the PTPN1 gene. Mutations were found in 6 of 30 (20%) Hodgkin lymphoma cases, in 6 of 9 (67%) Hodgkin lymphoma-derived cell lines, in 17 of 77 (22%) PMBCL cases and in 1 of 3 (33%) PMBCL-derived cell lines, consisting of nonsense, missense and frameshift mutations. We demonstrate that PTPN1 mutations lead to reduced phosphatase activity and increased phosphorylation of JAK-STAT pathway members. Moreover, silencing of PTPN1 by RNA interference in Hodgkin lymphoma cell line KM-H2 resulted in hyperphosphorylation and overexpression of downstream oncogenic targets. Our data establish PTPN1 mutations as new drivers in lymphomagenesis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Primary mediastinal large B-cell lymphoma (PMBCL) is a distinct subtype of diffuse large B-cell lymphoma thought to arise from thymic medullary B cells. Gene mutations underlying the molecular ...pathogenesis of the disease are incompletely characterized. Here, we describe novel somatic IL4R mutations in 15 of 62 primary cases of PMBCL (24.2%) and in all PMBCL-derived cell lines tested. The majority of mutations (11/21; 52%) were hotspot single nucleotide variants in exon 8, leading to an I242N amino acid change in the transmembrane domain. Functional analyses establish this mutation as gain of function leading to constitutive activation of the JAK-STAT pathway and upregulation of downstream cytokine expression profiles and B cell–specific antigens. Moreover, expression of I242N mutant IL4R in a mouse xenotransplantation model conferred growth advantage in vivo. The pattern of concurrent mutations within the JAK-STAT signaling pathway suggests additive/synergistic effects of these gene mutations contributing to lymphomagenesis. Our data establish IL4R mutations as novel driver alterations and provide a strong preclinical rationale for therapeutic targeting of JAK-STAT signaling in PMBCL.
•Somatic IL4R mutations were identified in 24% of primary PMBCL cases (n = 62) and in 100% of PMBCL-derived cell lines.•IL4R mutations lead to hyperphosphorylation of STAT proteins activating downstream immunoregulatory genes (CD23, CCL17).
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TLR2 plays a key role in the initiation of the cellular innate immune responses by a wide range of bacterial products. TLRs signaling, including TLR2 and its coreceptors TLR1 and TLR6, is mediated by ...a number of specific ligands. Although many of the TLR-mediated cell signaling pathways have been elucidated in the past few years, the molecular mechanisms that lead to cell activation are still poorly understood. In this study, we investigate the interaction of PorB from Neisseria meningitidis with TLR2 and describe the direct binding of a bacterial protein to TLR2 for the first time. Using labeled PorB, we demonstrate its binding to TLR2 both in its soluble form in vitro, and when it is over-expressed on the surface of human embryonic kidney 293 cells. We also show that TLR2-mediated binding of PorB is directly related to cellular activation. In addition, using 293 cells expressing the chimeric TLR2/TLR1 and TLR2/TLR6 complexes, we report the selectivity of PorB binding to the TLR2/TLR1 heterodimer, which is required for initiating signaling in transfected 293 cells and in murine B cells. Together, these data provide new evidence that TLR2 recognizes PorB through direct binding, and that PorB-induced cell activation is mediated by a TLR2/TLR1 complex.
Summary
Childhood obesity is rapidly increasing in prevalence. We compared circulating membrane‐bound tissue factor (FIII, F3) procoagulant activity (TF‐PCA) and plasma markers of coagulation, ...fibrinolysis and endothelial dysfunction in 21 obese (10·1 ± 1·5 years, mean ± standard deviation) and 22 healthy weight children (9·9 ± 1·6 years), classified by Body Mass Index (BMI). TF‐PCA and factor VII coagulant activity (FVII:C), plasminogen activator inhibitor (PAI‐1, SERPINE1) and soluble vascular cell adhesion molecule 1 (sVCAM1) were higher in obese children. BMI correlated positively with TF‐PCA, FVII:C, and PAI‐1. Childhood obesity is associated with a procoagulant state and endothelial dysfunction. Studies are needed to assess whether weight reduction reverses these abnormalities.
Meningococcal porin PorB is an inhibitor of apoptosis induced via the intrinsic pathway in various cell types. This effect is attributed to prevention of mitochondrial depolarization and of ...subsequent release of proapoptotic mitochondrial factors. To determine whether apoptosis is globally inhibited by PorB, we compared the intrinsic and extrinsic pathways in HeLa cells. Interestingly, PorB does not prevent extrinsic apoptosis induced by tumor necrosis factor alpha plus cycloheximide, suggesting a unique mitochondrial pathway specificity. Several intracellular factors regulated by NF-κB, including members of the Bcl-2 family and of the inhibitor of apoptosis (IAP) family, play major roles in controlling apoptosis, and some of them are thought to contribute to the antiapoptotic effect of the gonococcal porin, PIB. However, most of the members of the Bcl-2 family and the IAP family are not induced by meningococcal PorB in HeLa cells, with the exception of Bfl-1/A1. Interestingly, PorB does not induce NF-κB activation in HeLa cells, likely due to a lack of Toll-like receptor 2 (TLR2) expression in these cells. Bfl-1/A1 expression is also regulated by CBF1, a nuclear component of the Notch signaling pathway, independent of NF-κB activation. Since HeLa cells are protected by PorB from intrinsic apoptosis events, regardless of TLR2 and NF-κB expression, the possibility of a contribution of alternative signaling pathways to this effect cannot be excluded. In this paper, we describe an initial dissection of the cascade of cellular events involved in the antiapoptotic effect of PorB in the absence of TLR2.
Follicular lymphoma (FL) is the most common indolent non‐Hodgkin lymphoma. Twenty to twenty‐five percent of FL patients have progression of disease within 24 months. These patients may benefit from ...immunotherapy if intact antigen presentation is present. Molecular mechanisms impairing major histocompatibility complex class‐I (MHC‐I) in FL remain undefined. Here, by sequencing of 172 FL tumours, we found the MHC‐I transactivator NLRC5 was the most frequent gene abnormality in the MHC‐I pathway. Pyrosequencing showed that epigenetic silencing of the NLRC5 promoter occurred in 30% of cases and was mutually exclusive to copy number loss (CNL) in NLRC5 (∼6% of cases). Hypermethylation and CNLs (“NLRC5 aberrant”) had reduced NLRC5 gene expression compared to wild‐type (WT) cases. By NanoString, there was reduced gene expression of the MHC‐I pathway in aberrant tissues, including immunoproteasome components (PSMB8 and PSMB9), peptide transporters of antigen processing (TAP1), and MHC‐I (HLA‐A), compared to WT. By immunofluorescent microscopy, fewer NLRC5 protein‐expressing malignant B‐cells were observed in NLRC5 aberrant tissue sections compared to NLRC5 WT (P < .01). Consistent with a pivotal role in the activation of CD8+ T‐cells, both CD8 and CD137 strongly correlated with NLRC5 expression (both r > 0.7; P < .0001). Further studies are required to determine whether patients with aberrant NLRC5 have a diminished response to immunotherapy.
Objectives
A diverse intratumoral T‐cell receptor (TCR) repertoire is associated with improved survival in diffuse large B‐cell lymphoma (DLBCL) treated with ...rituximab/cyclophosphamide/doxorubicin/prednisolone/vincristine (R‐CHOP) chemoimmunotherapy. We explored the impact of intratumoral TCR repertoire on interim PET (iPET) done after four cycles of R‐CHOP, the relationships between intratumoral and circulating repertoire, and the phenotypes of expanded clonotypes.
Methods
We sequenced the third complementarity‐determining region of TCRβ in tumor samples, blood at pre‐therapy and after four cycles of R‐CHOP in 35 patients enrolled in ALLGNHL21 trial in high‐risk DLBCL. We correlated the TCR diversity metrics with iPET status, gene expression profiles and HLA‐class I genotypes. We then sequenced the FACS‐sorted peripheral blood T cells in six patients, and pentamer‐sorted EBV‐specific CD8+ T cells in one patient from this cohort.
Results
Compared with iPET− patients, the intratumoral TCR repertoire in iPET+ patients was characterised by higher cumulative frequency of abundant clonotypes and higher productive clonality. There was a variable overlap between circulating and intratumoral repertoires, with the dominant intratumoral clonotypes more likely to be detected in the blood. The majority of shared clonotypes were CD8+ PD‐1HI T cells, and CD8+ T cells had the largest clonal expansions in tumor and blood. In a patient with EBV+ DLBCL, EBV‐specific intratumoral clonotypes were trackable in the blood.
Conclusion
This study demonstrates that clonally expanded intratumoral TCR repertoires are associated with iPET+ and that the blood can be used to track tumor‐associated antigen‐specific clonotypes. These findings assist the rationale design and therapeutic monitoring of immunotherapeutic strategies in DLBCL.
In a cohort of high‐risk diffuse large B‐cell lymphoma patients enrolled in phase 2 clinical trial, clonally expanded intratumoral TCR repertoires were associated with a positive interim PET scans. Abundant intratumoral clonotypes were identified in peripheral blood at baseline and during chemoimmunotherapy.
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