scholarly journals ASB2 is a direct target of FLI1 that sustains NF-κB pathway activation in germinal center-derived diffuse large B-cell lymphoma

Author(s):  
Giulio Sartori ◽  
Sara Napoli ◽  
Luciano Cascione ◽  
Elaine Yee Lin Chung ◽  
Valdemar Priebe ◽  
...  

Abstract Background Diffuse large B-cell lymphoma (DLBCL) comprises at least two main biologically distinct entities: germinal center B-cell (GCB) and activated B-cell (ABC) subtype. Albeit sharing common lesions, GCB and ABC DLBCL present subtype-specific oncogenic pathway perturbations. ABC DLBCL is typically characterized by a constitutively active NF-kB. However, the latter is seen in also 30% of GCB DLBCL. Another recurrent lesion in DLBCL is an 11q24.3 gain, associated with the overexpression of two ETS transcription factors, ETS1 and FLI1. Here, we showed that FLI1 is more expressed in GCB than ABC DLBCL and we characterized its transcriptional network. Methods Gene expression data were obtained from public datasets GSE98588, phs001444.v2.p1, GSE95013 and GSE10846. ChIP-Seq for FLI1 paired with transcriptome analysis (RNA-Seq) after FLI1 silencing (siRNAs) was performed. Sequencing was carried out using the NextSeq 500 (Illumina). Detection of peaks was done using HOMER (v2.6); differential expressed genes were identified using moderated t-test (limma R-package) and functionally annotated with g:Profiler. ChIP-Seq and RNA-Seq data from GCB DLBCL cell lines after FLI1 downregulation were integrated to identify putative direct targets of FLI1. Results Analysis of clinical DLBCL specimens showed that FLI1 gene was more frequently expressed at higher levels in GCB than in ABC DLBCL and its  protein levels were higher in GCB than in ABC DLBCL cell lines. Genes negatively regulated by FLI1 included tumor suppressor genes involved in negative regulation of cell cycle and hypoxia. Among positively regulated targets of FLI1, we found genes annotated for immune response, MYC targets, NF-κB and BCR signaling and NOTCH pathway genes. Of note, direct targets of FLI1 overlapped with genes regulated by ETS1, the other transcription factor gained at the 11q24.3 locus in DLBCL, suggesting a functional convergence within the ETS family. Positive targets of FLI1 included the NF-κB-associated ASB2 a putative essential gene for DLBCL cell survival. ASB2 gene downregulation was toxic in GCB DLBCL cell lines and induced NF-κB inhibition via downregulation of RelB and increased IκBα. Additionally, downregulation of FLI1, but not ASB2, caused reduction of NF-κB1 and RelA protein levels. Conclusions We conclude that FLI1 directly regulates a network of biologically crucial genes and processes in GCB DLBCL. FLI1 regulates both the classical NF-κB pathway at the transcriptional level, and the alternative NF-κB pathway, via ASB2. FLI1 and ASB2 inhibition represents a potential novel therapeutic approach for GCB DLBCL.

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Danxia Zhu ◽  
Cheng Fang ◽  
Wenting He ◽  
Chen Wu ◽  
Xiaodong Li ◽  
...  

We investigated the role of miR-181a in diffuse large B-cell lymphoma (DLBCL) and its potential target genes. miR-181a levels were lower in activated B-cell- (ABC-) like DLBCL cells than that in germinal center B-cell- (GCB-) like DLBCL cells. Overexpression of miR-181a in ABC-like DLBCL cell lines (OCI-LY10 and U2932) resulted in G0/G1 cell cycle arrest, increased apoptosis, and decreased invasiveness. miRNA target prediction programs (miRanda, TargetScan, and miRDB) identified caspase recruitment domain-containing protein 11 (CARD11) as a putative miR-181a target. CARD11 mRNA and protein levels were higher in the ABC-like DLBCL than that in GCB-like DLBCL. Moreover, CARD11 mRNA and protein levels were downregulated in the OCI-LY10 and U2932 cell lines overexpressing miR-181a. Dual luciferase reporter assays confirmed the miR-181a binding site in the CARD11 3′UTR region. OCI-LY10 and U2932 cells transfected with a CARD11 expression vector encoding miR-181a with a mutated binding site showed higher CARD11 protein levels, cell viability, G2/M phase cells, and invasiveness compared to those transfected with a wild-type CARD11 expression vector. Nude mice xenografted with OCI-LY10 cells with overexpressed wild-type miR-181a generated smaller tumors compared to those with overexpressed mutated binding site of CARD11 3′UTR and miR-181a. These results indicate that miR-181a inhibits ABC-like DLBCL by repressing CARD11.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 242-242 ◽  
Author(s):  
Hovav Nechushtan ◽  
Joseph D. Rosenblatt ◽  
Izidore S. Lossos

Abstract Diffuse Large B-cell Lymphoma (DLBCL) represent a diverse group of lymphoid neoplasms with heterogeneous clinical, histological, immunophenotypic, cytogenetic and molecular genetic features. Approximately 50% of DLBCL patients are not cured by the standard combination chemotherapy regimens. DLBCL can be subclassified into GCB-like DLBCL which are characterized by expression of genes normally expressed in germinal center B cells, and having a significantly better overall survival (OS) than the ABC-like DLBCL, which are characterized by expression of genes induced during in vitro activation of normal B cells. At least two markers of the GCB-phenotype - BCL6 and HGAL - are IL-4 target genes, increased expression of which independently predicts better OS. These observations suggest that endogenous or exogenously administered IL-4 may influence behavior of DLBCL. IL-4 mRNA was detected at low levels in 5 of 7 GCB-like and in all 4 ABC-like DLBCL tumor specimens. Two of 7 GCB-like tumors showed high expression levels of IL-4 as determined by real-time RT-PCR. Examination of the effects of IL-4 on proliferation of GCB-like (SUDHL6, SUDHL4 and OCILY19) and ABC-like (OCILY10 and OCILY3) DLBCL cell lines showed that IL-4 mildly increased DNA synthesis, as assessed by thymidine incorporation, in all the GCB-like DLBCL. Conversely, IL-4 markedly decreased proliferation in the ABC-like DLBCL cell lines by inducing G1 arrest. IL-4 also differently affected the sensitivity of GCB-like and ABC-like DLBCL to doxorubicin. IL-4 reduced doxorubicin-induced cell death of ABC-like cell lines (20–50% reduction) while it markedly increased the killing of the GCB-like cells (40–80% induction). IL-4 also prevented serum starvation-induced cell death of the ABC-like DLBCL, but it increased cell death of the GCB-like DLBCL cell lines. Recently, Rituximab was shown to improve survival of DLBCL patients when added to the CHOP regimen. The precise mechanisms of its action are unknown; however present data suggest that it may affect lymphoma cells either by activation of complement lysis or by mediating ADCC. IL-4 reduced the complement mediated Rituximab cell lysis of the ABC-like cell lines, while it increased the complement mediated Rituximab cell lysis of the GCB-like DLBCL cell lines. Expression levels of surface markers that modulate complement cell lysis (CD46, CD55 and CD59) were not affected by IL-4 exposure. In contrast, IL-4 did not affect killing of GCB-like and ABC-like cells by ADCC. These observations suggest that DLBCL subtypes may respond differently to the in vivo cytokine milieu of the tumor. Different responsiveness to IL-4 may modulate tumor sensitivity to the current therapeutic modalities and can potentially be explored to augment response to chemotherapy and Rituximab.


Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3002-3002
Author(s):  
Charles H. Lawrie ◽  
Shamit Soneji ◽  
Christopher D. Cooper ◽  
Chris Hatton

Abstract MicroRNAs (miRNA) are a recently discovered class of short non-coding RNA molecules that negatively regulate gene expression. They have been shown to play a critical role in many biological functions. In humans about 320 miRNAs have been identified, some of which are expressed in a cell-specific and developmental stage-specific manner. Recently it has been shown that the expression profile of miRNAs can be used to subtype clinical cases (and cell lines) according to diagnosis with a greater degree of accuracy than traditional gene expression analysis. The identity of miRNAs associated with different lymphoma types however remains poorly defined. Previous expression studies have revealed the presence of at least two subtypes of diffuse large B-cell lymphoma (DLBCL) representing the postulated cell of origin; those that are germinal center B cell derived (GCB-type) and those that are activated B-cell derived (ABC-type). The latter subtype has been linked with poor prognostic outcome. It is not known whether these subtypes are also defined at the miRNA level. Therefore we examined the miRNA expression profile of DLBCL cell lines of defined subtypes as well as sub-populations of B-lymphocytes by microarray analysis. Consistent with recent publications, we found that mir-19a, 19b and 17-5p (part of mir-17-92 cluster) were up-regulated in cell lines but not in normal lymphocyte populations. Furthermore, cluster analysis showed that GCB-type cell lines (SUD-HL4, SUD-HL6 & SUD-HL10) have a distinct miRNA profile from ABC-type cell lines (OCI-Ly3 & OCI-Ly10). Most notably, high levels of expression of mir-155, mir-181b and mir-325 were found in ABC-type cell lines whilst high levels of mir-181a were found in GCB-type cell lines. We looked at expression of mir-155, 181a, 143, 145, 378 and 16 in these cell lines as well as clinical cases of DLBCL by RNase-protection assay. Consistent with the microarray data, we found that mir-155 was expressed in ABC-type cell lines but not GCB-type cell lines whilst the converse was true for mir-181a. Clinical cases showed similar patterns of expression but have still to be sub-typed according to immunohistochemical markers. Although still preliminary, our data suggests that miRNA profiling may be a useful tool in predicting the subtype of DLBCL cases and hence clinical outcome.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3733-3733 ◽  
Author(s):  
Jennifer E Amengual ◽  
Matko Kalac ◽  
Luigi Scotto ◽  
Patrick A Sleckman ◽  
Enrica Marchi ◽  
...  

Abstract Abstract 3733 Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin's Lymphoma. Despite advances in treatment, 1/3 of patients die from their disease. Gene expression profiling has delineated three subtypes with different genetic features known to be prognostic: the Activated B-cell (ABC), Germinal Center (GC), and grey zone types. For example, ABC DLBCL is addicted to NFkB over-expression. The oncogene, BCL6, encodes a transcription factor that functions as a transcriptional repressor within normal germinal center B-cells. Constitutive activation of Bcl-6 leads to GC-type DLBCL by turning off genes expressing cell cycle dependent kinase inhibitors, and essential tumor suppressor genes, like p53. There is a critical inverse relationship between Bcl-6 and p53, the functional status of which is linked to each transcription factor's degree of acetylation. Deacetylation of Bcl-6 is required for maintaining its effects as a transcriptional repressor. Conversely, acetylation of p53 is activating when class III histone deacetylases (HDAC), also known as sirtuins, are inhibited by drugs such as niacinamide. HDAC inhibitors are presently approved for T-cell lymphoma and may require the targeting of additional pathways to be effective in B-cell lymphomas. Trichostatin A and niacinamide modulate Bcl-6 in lymphoma cell lines. One therapeutic strategy that could favorably shift the relationship between oncogenes and tumor suppressors is the pharmacologic modification of Bcl-6 and p53 using HDAC inhibitors. Eight DLBCL cell lines were screened (4 ABC: Su-DHL2, HBL-1, OCI-Ly10, RIVA; 4 GC:OCI-Ly1, OCI-Ly7, Su-DHL6, Su-DHL4) with four class I/II HDAC inhibitors (romidepsin, vorinostat, panobinostat and belinostat) in combination with niacinamide (sirtuin inhibitor) at two dose levels each at three time points. Cell growth inhibition was measured by luminescence cell viability and apoptosis flow cytometry assays. Synergy was measured by the relative risk ratio (RRR) calculation where values <1 represent synergy. Synergy was achieved in significantly greater number and intensity in the GC versus ABC cell lines. Specifically, romidepsin in combination with niacinamide achieved the greatest synergy. To analyze mechanism of action, DLBCL cell lines were treated with combinations of class I/II HDAC inhibitors and niacinamide. Cells of both GC and ABC subtypes treated with the combination resulted in increased acetylation of p53, and increased p21 and BLIMP-1 content compared to controls. These results did not correlate with cytotoxicity as the ABC cell lines did not achieve the same synergy as the GC cells. GC cells treated with the same combinations resulted in acetylation of Bcl-6 compared with controls as measured by immunoprecipitation and Western blotting assays; ABC cells do not express Bcl-6. This finding correlated with cytotoxicity implying that a rational second pathway must be targeted to shift the balance between oncogene and tumor suppressor activity to achieve effective cell kill. p300 content was also increased suggesting that treatment with HDAC inhibitors recruit or upregulate its production and activity leading to increased acetylation. Using a novel double transgenic mouse model of aggressive spontaneous B-cell lymphoma (l-myc overexpressing crossed with CD19-tagged mCherry luciferase), in vivo effects of the drug combination were studied. These mice express equal basal amounts of Bcl-6 and p53 as GC cell lines. Mice treated with niacinamide 20 mg/kg and romidepsin 2.3mg/kg IP for 5 hours achieved increased acetylation of Bcl-6 and p53, and accumulation of p21 and BLIMP1 compared with controls. Importantly, mice treated with the combination of niacinamide 40 mg/kg and romidepsin 2.3 mg/kg IP achieved decreased tumor burden as measured by bioluminescence signal intensity compared to mice treated with each drug alone and controls. Presently, we are translating these concepts and observations in a proof-of-principle phase I trial evaluating the safety of vorinostat plus niacinamide in lymphoid malignancies. By targeting the specific pathogenetic features of DLBCL, it may be possible to tailor future treatment platforms for discrete subtypes of DLBCL. Disclosures: Off Label Use: The drugs evaluated are not approved for use in DLBCL. O'Connor:Celgene: Consultancy, Research Funding; Merck: Research Funding; Novartis: Research Funding; Spectrum: Research Funding.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 643-643
Author(s):  
Julie Marie Matthews ◽  
Li Tan ◽  
Shruti Bhatt ◽  
Matthew Patricelli ◽  
Tyzoon Nomanbhoy ◽  
...  

Abstract Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL). The pathogenesis of DLBCL represents a multi-step process that involves the accumulation of multiple genetic and molecular lesions. Marked advances in the understanding of DLBCL pathobiology have been made by the application of gene expression arrays, comparative genomic hybridization arrays and “next” generation sequencing. This led to the identification of previously unrecognized DLBCL subtypes (germinal center-like (GCB) and activated B cell-like (ABC)) as well as type specific-deregulation of particular signaling pathways. These approaches focused on genetic aberrations and mRNA expression profiles, whereas the crucial events transforming normal cells are executed by proteins. Kinases play an important role in neoplastic transformation. Herein, we have undertaken the task of profiling kinase activity in DLBCL to further delineate potential mechanisms of DLBCL pathogenesis and develop novel therapeutic agents. A comprehensive analysis of global kinase activity/protein expression was performed using KiNativ technology. Kinomic analysis of 8 DLBCL cell lines, as compared to non-cancerous primary B-cells, led to the discovery of 13 members of the MAPK cascade which were activated and/or overexpressed in DLBCL. Only three of the detected MAPK members were inactive or had reduced expression compared to their non-cancerous counterparts. To determine whether these findings could be extended to de novo primary human DLBCL tumors, we performed immunohistochemistry (IHC) of the proximally activated kinase, MAP4K2 or “Germinal Center Kinase” (GCK) and the phosphorylated forms of its downstream targets: MAP3K1, MAP2K4, MAP2K7, and C-jun N-terminal Kinase 1 (JNK1). Analyzed kinases were expressed and activated in more than 80% of primary DLBCL tumors, confirming the KiNativ cell line data. The kinase array data was further corroborated with classical immunoprecipitation-based JNK and p38 assays. Hierarchical clustering analysis of 36 DLBCL specimens stained for GCB and ABC markers demonstrated that GCK expression/activation is not DLBCL subtype specific. Notably, in a cohort of 151 primary DLBCL cases, we found that patients whose tumors did not express GCK had an estimated progression free survival (PFS) of 85% at 10 years of follow up, whereas those tumors expressing GCK were associated with significantly reduced PFS of 53% (p=0.04). While there was a similar trend in overall survival, it did not reach statistical significance, which may be due to the relatively small number of DLBCL cases not expressing GCK and the potential rescue of these patients with second line treatments. RNA interference studies in DLBCL cell lines confirmed the importance of GCK for the survival of these tumors, resulting in reduced viability and G0/G1 arrest. We next developed a small molecule inhibitor, HG6-64-1. KiNativ, Ambit and Invitrogen profiling of HG6-64-1 targets revealed that it potently inhibited GCK. In vitro treatment with the novel GCK inhibitor, HG6-64-1, led to cell cycle arrest and the induction of apoptosis in DLBCL cell lines and primary DLBCL tumors. G452, a DLBCL cell line minimally expressing GCK, was not affected by HG6-64-1. In vivo treatment with HG6-64-1, via intratumoral and intraperitoneal injections, significantly decreased the tumor growth rate resulting in a significantly extended lifespan of DLBCL xenograft mouse models. Overall our results identified a previously unrecognized activation of the GCK pathway which contributes to the proliferation and survival of DLBCLs and can be used as a therapeutic target using novel GCK inhibitors. Disclosures: Patricelli: ActivX Biosciences: Employment. Nomanbhoy:ActivX Biosciences: Employment.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2253-2253 ◽  
Author(s):  
Silvia L Locatelli ◽  
Roberto Papait ◽  
Giuseppa Careddu ◽  
Ada Koschorke ◽  
Giuliano G Stirparo ◽  
...  

Abstract INTRODUCTION: Lenalidomide monotherapy exerts clinical activity in relapsed/refractory Diffuse Large B-cell Lymphoma (DLBCL) with better response rate and progression-free survival being recorded in activated B-cell-like (ABC) rather than germinal center B-cell-like (GCB)-DLBCL. Reasons for such a difference are likely due to different expression of key molecules involved in mediating activity of Lenalidomide, such as Interferon regulatory factor 4(IRF4) and cereblon (CRBN). Evidences supporting the key role of DNA methylation and histone modifications in regulating genome stability and gene expression in DLBCL prompted us to investigate the capacity of Azacytidine in modulating Lenalidomide activity, thereby sensitizing GCB-DLBCL to Lenalidomide and enhancing Lenalidomide efficacy in ABC-DLBCL. METHODS: DLBCL cell lines with ABC (U-2932, RIVA) or GCB (SU-DHL4, SU-DHL6) genotype were used to investigate the effects of Lenalidomide and Azacytidine on cell growth and cell death. Western blotting (WB) and immunofluorescence analysis were used to assess modulating effects of the two-drug combination on molecular determinants of Lenalidomide activity. Additionally, we studied CRBN, IRF4 and CRBN binding proteins expression, such as Ikaros and Aiolos (IKZF1 and IKZF3) by real time polymerase chain reaction (RT-PCR) in response to drug treatment. RESULTS: Graded concentrations of Lenalidomide (0.1-100 µM) inhibited cell proliferation by 20% to 40% and increased cell death up to 30% to 40% in ABC-DLBCL cell lines, whereas had minimal effects on GCB-DLBCL cell lines. Untreated ABC-DLBCL but not GCB-DLBCL consistently showed a high expression of CRBN and IRF4. Upon Lenalidomide treatment (3 days) CRBN was significantly upregulated and IRF4 downregulated in ABC-DLBCL, but not GCB-DLBCL cells. Since DNA methylation regulates gene expression in DLBCL cell lines, we next examined whether Azacytdine could modulate CRBN and IRF4 expression and in turn enhance responsiveness to Lenalidomide. Exposure of both ABC- and GCB-DLBCL cell lines to Azacytidine (up to 72 hours) induced a marked increase of CRBN and IRF4 transcripts; addition of Lenalidomide strongly increased Azacytidine-induced increase of CRBN and significantly downregulated IRF4 expression; the combined treatment induced a marked downregulation of Ikaros and Aiolos protein levels. At the cellular level, the concomitant Azacytidine (10 μM)/Lenalidomide (10 μM) treatment inhibited in a synergistic manner the mean (±SEM) cell growth of both ABC-DLBCL (Lena: -16 ± 4%; AZA: -22 ± 2%; AZA/Lena: -70 ± 1%, P<0.001) and GCB-DLBCL (Lena: -17 ± 3%; AZA: -40 ± 4%; AZA/Lena: -82 ± 2%, P<0.001). Additionally, the two drug exposure was associated with a 3-fold decrease of S phase cells(Lena: 28 ± 2%; AZA: 22 ± 0.8%; AZA/Lena: 9 ± 1%, P<0.001); a marked p21 overexpression, and a 3- to 4-fold cell death increase (P<0.001) in both ABC- and GCB-DLBCL. CONCLUSIONS: Our results indicate that Azacytidine sensitizes GCB-DLBCL to the cytotoxic effects of Lenalidomide and enhances Lenalidomide efficacy against ABC-DLBCL resulting in synergistic anti-proliferative and pro-apoptotic effects in both ABC- and GCB-DLBCL cell lines. Cytotoxicity of the two drug combination is mediated by signaling events involving CRBN upregulation and IRF4 downregulation leading to CRBN-binding proteins downregulation. Azacytidine-dependent activation of CRBN and IRF4 expression allow to hypothesize a methylation-driven regulation of these genes. These results might provide a rationale for clinical studies using Azacytidine and Lenalidomide combination in ABC- and GCB-DLBCL. Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2016 ◽  
Vol 128 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Julie Marie Matthews ◽  
Shruti Bhatt ◽  
Matthew P. Patricelli ◽  
Tyzoon K. Nomanbhoy ◽  
Xiaoyu Jiang ◽  
...  

Key Points GCK signaling is activated in DLBCL, and this signaling is important to DLBCL proliferation and survival. Therapeutic targeting of GCK is feasible and may advance efforts to cure DLBCL patients.


Blood ◽  
2016 ◽  
Vol 127 (12) ◽  
pp. 1564-1574 ◽  
Author(s):  
Tibor Bedekovics ◽  
Sajjad Hussain ◽  
Andrew L. Feldman ◽  
Paul J. Galardy

Key Points The neuronal marker UCH-L1 is induced in, and specifically augments the oncogene-induced transformation of, GCB cells. High levels of UCHL1 identify patients with GC DLBCL with an increased risk for poor outcomes.


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