Analysis of differential gene expression in NFKBIE-mutated and non-mutated primary mediastinal B-cell lymphoma (PMBL) via NanoString mRNA expression profiling.
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ABSTRACT: We recently reported a truncating deletion in the NFKBIE gene, which encodes IκBε, a negative feedback regulator of NF-κB, in clinically aggressive chronic lymphocytic leukemia (CLL). Preliminary data indicate enrichment of NFKBIE aberrations in other lymphoid malignancies, hence we screened a large patient cohort (n=1460) diagnosed with different lymphoid neoplasms. We observed a a remarkably high frequency of NFKBIE aberrations (46/203 cases, 22,7%) in primary mediastinal B-cell lymphoma (PMBL). The deletion was associated with a particular aggressive clinical course and reduced survival in multivariate analysis. With gene expression profiling (GEP) via the NanoString nCounter hybridization system and the NanoString GX Human PanCancer Pathway Panel including 30 additional custom genes, the aim of this analysis was to study the differential activation of various oncogenic pathways including NFKB-signaling in NFKBIE mutated vs. non-mutated PMBL.
Project description:Analysis of differential gene expression in NFKBIE-mutated and non-mutated primary mediastinal B-cell lymphoma (PMBL) via NanoString mRNA expression profiling.
Project description:Primary mediastinal large B-cell lymphoma (PMBL) represents a clinically and pathologically distinct subtype of large B-cell lymphomas. Furthermore, molecular studies, including global gene expression profiling, have provided evidence that PMBL is more closely related to classical Hodgkin lymphoma (cHL). Although targeted sequencing studies have revealed a number of mutations involved in PMBL pathogenesis, a comprehensive description of disease-associated genetic alterations and perturbed pathways is still lacking. Here, we performed whole-exome sequencing of 95 PMBL tumors to inform on oncogenic driver genes and recurrent copy number alterations. The integration of somatic gene mutations with gene expression signatures provides further insights into genotype-phenotype interrelation in PMBL. We identified highly recurrent oncogenic mutations in the JAK-STAT and NF-kB pathways, and provide additional evidence of the importance of immune evasion in PMBL (CIITA, CD58, B2M, CD274, PDCD1LG2). Our analyses highlight the IRF-pathway as a putative novel hallmark with frequent alterations in multiple pathway members (IRF2BP2, IRF4, IRF8). In addition, our integrative analysis illustrates the importance of JAK1, RELB and EP300 mutations driving oncogenic signaling. The identified driver genes were significantly more frequently mutated in PMBL as compared to diffuse large B-cell lymphoma, whereas only a limited number of genes were significantly different between PMBL and cHL, emphasizing the close relationship between these entities. Our study, performed on a large cohort of PMBL, highlights the importance of distinctive genetic alterations for disease taxonomy with relevance for diagnostic work-up and therapeutic decision-making.
Project description:Development of primary mediastinal B-cell lymphoma (PMBL) is driven by cumulative genomic aberrations. It is unknown whether copy-neutral loss of heterozygosity (CN-LOH) contributes to the pathogenesis of this tumor. To get insight into the CN-LOH landscape of PMBL, we performed Single Nucleotide Polymorphism array (SNPa) analysis of two PMBL-derived cell lines and 33 primary tumors. The study uncovered large-scale CN-LOH lesions in both cell lines and 90.9% (30/33) of primary tumors. The latter cases showed 133 CN-LOH stretches of size >25Mb which affected up to 14 chromosomes per case (mean of 4.4). Involvement of chromosomal segments was predominant (81.2%), which, in a heterozygous diploid context, suggests the implication of B-cell specific crossover events. Further analysis indicated that the CN-LOH lesions were triggered by one or two consecutive molecular hits. Notably, CN-LOH segments were non-randomly clustered on chromosome 6p (60%), 15 (37.2%) and 17q (40%). Preliminary whole-exome sequencing data yielded coincidence of these lesions with mutations in MHC I and histon-related genes (6p21), B2M (15q15) and GNA13 (17q23), respectively. We hypothesize that CN-LOH-associated hits occurred early during lymphomagenesis, following mutagenesis but preceding genomic gains. Screening of the cohort of 2,658 cancer whole-genomes revealed that the CN-LOH landscape in PMBL is unique and distinguishes this tumor from other malignancies. Altogether, CN-LOH lesions rank as the most frequent genetic defect identified so far in this disease and the CN-LOH landscape suggest a hitherto undescribed mitotic recombinational driver. The aberrations affect the expression of key driver genes and functionally alternate genomic deletions which are infrequent in PMBL.
Project description:Inactivating mutations in the NF-kB inhibitor NFKBIE are frequent in chronic lymphocytic leukemia (CLL) and have been associated with accelerated disease progression and inferior responses to chemotherapy. To further understand the role of NFKBIE mutations in CLL, we disrupted by CRISPR/Cas9 editing the NFKBIE gene in CLL cells derived from the Eμ-TCL1 transgenic mouse model and investigated how this will affect CLL growth and response to B cell receptor inhibitor treatment. In vitro and adoptive transfer experiments showed that NFKBIE-mutated cells have a growth advantage over NFKBIE-wild type cells when exposed to microenvironmental signals that activate the canonical NF-kB pathway and can induce alterations within the tumor microenvironment that may allow for escape from immune surveillance, including the expansion of CD8+ T cells with an exhausted phenotype and increased expression of PD-L1 on the malignant B cells. Consistent with these findings, significantly greater expression of the exhaustion markers PD1 and TIGIT was observed on T cells from CLL patients with NFKBIE-mutated compared to NFKBIE-wild type leukemia. In addition, in vitro and in vivo experiments showed that NFKBIE-mutated murine CLL cells are selectively resistant to BTK inhibitor treatment while remaining sensitive to treatment with a PI3K or SYK inhibitor. Reduced sensitivity to BTK inhibitor treatment was also observed in a series of 229 ibrutinib-treated CLL patients showing inferior outcomes for the NFKBIE-mutated cases. These findings provide evidence that NFKBIE-mutated CLL cells reshape and are selected by the tumor microenvironment and may account for suboptimal ibrutinib responses.
Project description:Primary Mediastinal large B-cell lymphoma (PMBL) is a rare form of non-Hodgkin lymphoma (NHL) representing 2% of mature B-cell NHL in patients less than 18 years of age.We compared the gene expression profiling between fully humanized anti-CD20 targeted monoclonal antibody recognizing a unique CD20 type II epitope, obinutuzumab and IgG or PBS treated Karpas Primary Mediastinal B-cell lymphoma (PMBL) cell line. -
Project description:Cell lines of mediastinal lymphomas, one each of primary mediastinal (thymic) large B cell lymphoma (PMBL), classic Hodgkin lymphoma (CHL), B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, and T-cell lymphoma were treated with rituximab (RmAb), brentuximab vedotin (BV), ibrutinib (IBR), prednisone (PRED) or untreated (UT) for 48 hours. Flow cytometry for PD-L1 protein was performed, and differential expression (DE) analysis of mRNA and miRNA performed by RNAseq. B-cell lines exhibited 2- fold increase in PD-L1 protein (p<.05) with RmAb compared to UT. Others showed no effect of RmAb, however, the T-cell line showed 2-fold increase on treatment with BV (P<.05). DE performed by limma showed no genomic level changes. ANOVA analysis of PMBL treated with RmAb, however, showed physiologic level DE involving >3000 genes involving multiple pathways associated with cell death and survival, protein degradation, mRNA translation, mRNA degradation, immunologic functions, and PD-1/PD-L1 immunotherapy. In the B cell lines, DE of CD274 (PD-L1) was decreased or not significant. MiRNA DE showed upregulation of 7 miRNAs, including miR-155-5p.
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:Micro RNAs (miRNAs) are a class of small, non-coding RNAs that post-transcriptionally control the translation and stability of mRNAs. In our study, we found a higher level of miR-92a in PMBL versus DLBCL. A bioinformatics approach combining in silico prediction and transcriptomic analyses on patient samples and transduced cell lines, enabled us to identify miR-92a target genes in PMBL.
Project description:Primary mediastinal large B-cell lymphoma (PMBL) is a type of aggressive B-cell lymphoma that typicallyaffects young adults, characterized by presence of a bulky anterior mediastinal mass. Lymphomas withgene expression features of PMBL have been described in non-mediastinal sites, raising questions abouthow these tumors should be classified.Here, we investigated whether these "non-mediastinal PMBLs" are indeed PMBLs or instead represent adistinct group within DLBCL. From a cohort of 325 de novo DLBCL cases, we identified tumors frompatients without evidence of anterior mediastinal involvement that expressed a PMBL expression signature(nm-PMBLsig-pos, n=16, 5%). The majority of these tumors expressed MAL and CD23 – proteins typicallyobserved in bona fide PMBL (bf-PMBL). Evaluation of clinical features of nm-PMBLsig-pos cases revealedclose associations with DLBCL, and the majority displayed a germinal center B-cell-like cell-of-origin(GCB). In contrast to bf-PMBL, nm-PMBLsig-pos patients presented at an older age, did not show pleuraldisease, and bone/bone marrow involvement was observed in three cases. However, while clinicallydistinct from bf-PMBL, nm-PMBL-sig-pos tumors resembled bf-PMBL at the molecular level with upregulationof immune response, JAK-STAT, and NF-kB signatures. Mutational analysis revealed frequent somatic genemutations in SOCS1, IL4R, ITPKB and STAT6, as well as CD83 and BIRC3, with the latter genes beingsignificantly more frequently affected than in GCB-DLBCL and bf-PMBL.Our data establish nm-PMBLsig-pos lymphomas as a group of DLBCL with distinct phenotypic and geneticfeatures, and potential implications for gene expression- and mutation-based subtyping of aggressive Bcell lymphoma and related targeted therapies.
Project description:Primary mediastinal large B-cell lymphoma (PMBL) represents a clinically and pathologically distinct subtype of large B-cell lymphomas. Furthermore, molecular studies, including global gene expression profiling, have provided evidence that PMBL is more closely related to classical Hodgkin lymphoma (cHL). Although targeted sequencing studies have revealed a number of mutations involved in PMBL pathogenesis, a comprehensive description of disease-associated genetic alterations and perturbed pathways is still lacking. Here, we performed whole-exome sequencing of 95 PMBL tumors to inform on oncogenic driver genes and recurrent copy number alterations. The integration of somatic gene mutations with gene expression signatures provides further insights into genotype-phenotype interrelation in PMBL. We identified highly recurrent oncogenic mutations in the JAK-STAT and NF-kB pathways, and provide additional evidence of the importance of immune evasion in PMBL (CIITA, CD58, B2M, CD274, PDCD1LG2). Our analyses highlight the IRF-pathway as a putative novel hallmark with frequent alterations in multiple pathway members (IRF2BP2, IRF4, IRF8). In addition, our integrative analysis illustrates the importance of JAK1, RELB and EP300 mutations driving oncogenic signaling. The identified driver genes were significantly more frequently mutated in PMBL as compared to diffuse large B-cell lymphoma, whereas only a limited number of genes were significantly different between PMBL and cHL, emphasizing the close relationship between these entities. Our study, performed on a large cohort of PMBL, highlights the importance of distinctive genetic alterations for disease taxonomy with relevance for diagnostic work-up and therapeutic decision-making.