Implant constructs supporting angiogenesis are favorable for treating critically-sized bone defects, as ingrowth of capillaries towards the center of large defects is often insufficient. ...Consequently, the insufficient nutritional supply of these regions leads to impaired bone healing. Implants with specially designed angiogenic supporting geometry and functionalized with proangiogenic cytokines can enhance angiogenesis. In this study, Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were used for incorporation into poly-
-caprolactone (PCL)-coated porous titanium implants. Bioactivity of released factors and influence on angiogenesis of functionalized implants were evaluated using a migration assay and angiogenesis assays. Both implants released angiogenic factors, inducing migration of endothelial cells. Also, VEGF-functionalized PCL-coated titanium implants enhanced angiogenesis
. Both factors were rapidly released in high doses from the implant coating during the first 72 h.
•MALT1 paracaspase acts as a bifurcation point for inducing transcriptional and posttranscriptional gene expression in malignant lymphomas.•MALT1 cleaves mRNA-destabilizing factors to enhance ...NF-κB–dependent and –independent gene induction in ABC DLBCL and MALT lymphoma.
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Constitutive mucosa–associated lymphoid tissue lymphoma translocation protein 1 (MALT1) activity drives survival of malignant lymphomas addicted to chronic B-cell receptor signaling, oncogenic CARD11, or the API2-MALT1 (also BIRC3::MALT1) fusion oncoprotein. Although MALT1 scaffolding induces NF-κB–dependent survival signaling, MALT1 protease function is thought to augment NF-κB activation by cleaving signaling mediators and transcriptional regulators in B-cell lymphomas. However, the pathological role of MALT1 protease function in lymphomagenesis is not well understood. Here, we show that TRAF6 controls MALT1-dependent activation of NF-κB transcriptional responses but is dispensable for MALT1 protease activation driven by oncogenic CARD11. To uncouple enzymatic and nonenzymatic functions of MALT1, we analyzed TRAF6-dependent and -independent as well as MALT1 protease–dependent gene expression profiles downstream of oncogenic CARD11 and API2-MALT1. The data suggest that by cleaving and inactivating the RNA binding proteins Regnase-1 and Roquin-1/2, MALT1 protease induces posttranscriptional upregulation of many genes including NFKBIZ/IκBζ, NFKBID/IκBNS, and ZC3H12A/Regnase-1 in activated B-cell–like diffuse large B-cell lymphoma (ABC DLBCL). We demonstrate that oncogene-driven MALT1 activity in ABC DLBCL cells regulates NFKBIZ and NFKBID induction on an mRNA level via releasing a brake imposed by Regnase-1 and Roquin-1/2. Furthermore, MALT1 protease drives posttranscriptional gene induction in the context of the API2-MALT1 fusion created by the recurrent t(11;18)(q21;q21) translocation in MALT lymphoma. Thus, MALT1 paracaspase acts as a bifurcation point for enhancing transcriptional and posttranscriptional gene expression in malignant lymphomas. Moreover, the identification of MALT1 protease–selective target genes provides specific biomarkers for the clinical evaluation of MALT1 inhibitors.
Despite the development of novel targeted drugs, the molecular heterogeneity of diffuse large B-cell lymphoma (DLBCL) still poses a substantial therapeutic challenge. DLBCL can be classified into at ...least 2 major subtypes (germinal center B cell GCB-like and activated B cell ABC-like DLBCL), each characterized by specific gene expression profiles and mutation patterns. Here we demonstrate a broad antitumor effect of dimethyl fumarate (DMF) on both DLBCL subtypes, which is mediated by the induction of ferroptosis, a form of cell death driven by the peroxidation of phospholipids. As a result of the high expression of arachidonate 5-lipoxygenase in concert with low glutathione and glutathione peroxidase 4 levels, DMF induces lipid peroxidation and thus ferroptosis, particularly in GCB DLBCL. In ABC DLBCL cells, which are addicted to NF-κB and STAT3 survival signaling, DMF treatment efficiently inhibits the activity of the IKK complex and Janus kinases. Interestingly, the BCL-2–specific BH3 mimetic ABT-199 and an inhibitor of ferroptosis suppressor protein 1 synergize with DMF in inducing cell death in DLBCL. Collectively, our findings identify the clinically approved drug DMF as a promising novel therapeutic option in the treatment of both GCB and ABC DLBCLs.
•As a result of low glutathione and glutathione peroxidase 4 levels and high 5-lipoxygenase expression, DMF induces ferroptosis in GCB DLBCL.•In ABC DLBCL, DMF induces succination of kinases IKK2 and JAK1, thus inhibiting NF-κB and JAK/STAT survival signaling.
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Dendritic cell (DC) maturation is a prerequisite for the induction of adaptive immune responses against pathogens and cancer. Transcription factor (TF) networks control differential aspects of early ...DC progenitor versus late-stage DC cell fate decisions. Here, we identified the TF C/EBPβ as a key regulator for DC maturation and immunogenic functionality under homeostatic and lymphoma-transformed conditions. Upon cell-specific deletion of C/EBPβ in CD11c⁺MHCIIhi DCs, gene expression profiles of splenic C/EBPβ−/− DCs showed a down-regulation of E2F cell cycle target genes and associated proliferation signaling pathways, whereas maturation signatures were enriched. Total splenic DC cell numbers were modestly increased but differentiation into cDC1 and cDC2 subsets were unaltered. The splenic CD11c⁺MHCIIhiCD64⁺ DC compartment was also increased, suggesting that C/EBPβ deficiency favors the expansion of monocytic-derived DCs. Expression of C/EBPβ could be mimicked in LAP/LAP* isoform knockin DCs, whereas the short isoform LIP supported a differentiation program similar to deletion of the full-length TF. In accordance with E2F1 being a negative regulator of DC maturation, C/EBPβ−/− bone marrow-derived DCs matured much faster enabling them to activate and polarize T cells stronger. In contrast to a homeostatic condition, lymphoma-exposed DCs exhibited an up-regulation of the E2F transcriptional pathways and an impaired maturation. Pharmacological blockade of C/EBPβ/mTOR signaling in human DCs abrogated their protumorigenic function in primary B cell lymphoma cocultures. Thus, C/EBPβ plays a unique role in DC maturation and immunostimulatory functionality and emerges as a key factor of the tumor microenvironment that promotes lymphomagenesis.
The protease MALT1 promotes lymphocyte activation and lymphomagenesis by cleaving a limited set of cellular substrates, most of which control gene expression. Here, we identified the integrin-binding ...scaffold protein Tensin-3 as a MALT1 substrate in activated human B cells. Activated B cells lacking Tensin-3 showed decreased integrin-dependent adhesion but exhibited comparable NF-κB1 and Jun N-terminal kinase transcriptional responses. Cells expressing a noncleavable form of Tensin-3, on the other hand, showed increased adhesion. To test the role of Tensin-3 cleavage in vivo, mice expressing a noncleavable version of Tensin-3 were generated, which showed a partial reduction in the T cell-dependent B cell response. Interestingly, human diffuse large B cell lymphomas and mantle cell lymphomas with constitutive MALT1 activity showed strong constitutive Tensin-3 cleavage and a decrease in uncleaved Tensin-3 levels. Moreover, silencing of Tensin-3 expression in MALT1-driven lymphoma promoted dissemination of xenografted lymphoma cells to the bone marrow and spleen. Thus, MALT1-dependent Tensin-3 cleavage reveals a unique aspect of the function of MALT1, which negatively regulates integrin-dependent B cell adhesion and facilitates metastatic spread of B cell lymphomas.
Activated B-cell-like (ABC) and germinal center B-cell-like diffuse large B-cell lymphoma (DLBCL) represent the 2 major molecular DLBCL subtypes. They are characterized by differences in clinical ...course and by divergent addiction to oncogenic pathways. To determine activity of novel compounds in these 2 subtypes, we conducted an unbiased pharmacologic in vitro screen. The phosphatidylinositol-3-kinase (PI3K) α/δ (PI3Kα/δ) inhibitor AZD8835 showed marked potency in ABC DLBCL models, whereas the protein kinase B (AKT) inhibitor AZD5363 induced apoptosis in PTEN-deficient DLBCLs irrespective of their molecular subtype. These in vitro results were confirmed in various cell line xenograft and patient-derived xenograft mouse models in vivo. Treatment with AZD8835 induced inhibition of nuclear factor κB signaling, prompting us to combine AZD8835 with the Bruton's tyrosine kinase inhibitor ibrutinib. This combination was synergistic and effective both in vitro and in vivo. In contrast, the AKT inhibitor AZD5363 was effective in PTEN-deficient DLBCLs through downregulation of the oncogenic transcription factor MYC. Collectively, our data suggest that patients should be stratified according to their oncogenic dependencies when treated with PI3K and AKT inhibitors.
•PI3Kα/δ inhibition induces cytotoxicity in ABC DLBCLs through downregulation of NF-κB signaling.•Inhibition of AKT induces cytotoxicity by downregulation of MYC in PTEN-deficient DLBCL models in vivo and in vitro.
Epstein-Barr virus (EBV) associated diffuse large B-cell lymphoma (DLBCL) represents a rare aggressive B-cell lymphoma subtype characterized by an adverse clinical outcome. EBV infection of lymphoma ...cells has been associated with different lymphoma subtypes while the precise role of EBV in lymphomagenesis and specific molecular characteristics of these lymphomas remain elusive. To further unravel the biology of EBV associated DLBCL, we present a comprehensive molecular analysis of overall 60 primary EBV positive (EBV+) DLBCLs using targeted sequencing of cancer candidate genes (CCGs) and genome-wide determination of recurrent somatic copy number alterations (SCNAs) in 46 cases, respectively. Applying the LymphGen classifier 2.0, we found that less than 20% of primary EBV + DLBCLs correspond to one of the established molecular DLBCL subtypes underscoring the unique biology of this entity. We have identified recurrent mutations activating the oncogenic JAK-STAT and NOTCH pathways as well as frequent amplifications of 9p24.1 contributing to immune escape by PD-L1 overexpression. Our findings enable further functional preclinical and clinical studies exploring the therapeutic potential of targeting these aberrations in patients with EBV + DLBCL to improve outcome.
Health-related quality of life (HRQoL) data are important indicators of health status in patients with lymphoma. The objective of this analysis was to assess the impact of treatment with Sandoz ...rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) on HRQoL in treatment-naïve adult patients with diffuse large B-cell lymphoma (DLBCL) included in the prospective, real-world REFLECT study. REFLECT is the first prospective study to assess HRQoL in patients with DLBCL treated with a rituximab biosimilar. HRQoL was assessed via the patient-reported European Organization for Research and Treatment of Cancer Core Quality of Life questionnaire at baseline, mid-treatment (month 3), end of treatment (month 6), and follow-up (months 9 and 12). Subgroup analyses were performed to evaluate the influence of baseline characteristics on HRQoL, and associations between baseline HRQoL and treatment response. HRQoL was assessed in 169 patients. Mean global health status score remained stable from baseline (54.8) to mid-treatment (month 3; 54.7), before steadily improving through to end of treatment (month 6; 61.4), and follow-up month 9 (64.9) and month 12 (68.8). Similar trends were observed across most functional and symptom subscales. Higher cognitive, physical, or role functioning, and less appetite loss, diarrhea, fatigue, or pain at baseline, were all associated with an improved likelihood of reaching a complete versus partial response at the end of treatment. Overall, these findings confirm the HRQoL benefits of R-CHOP therapy in treatment-naïve adult patients with DLBCL, and suggest that baseline HRQoL may be predictive of treatment response.
Diffuse large B-cell lymphoma (DLBCL) represents the most common adult lymphoma and can be divided into 2 major molecular subtypes: the germinal center B-cell-like and the aggressive activated ...B-cell-like (ABC) DLBCL. Previous studies suggested that chronic B-cell receptor signaling and increased NF-κB activation contribute to ABC DLBCL survival. Here we show that the activity of the transcription factor NFAT is chronically elevated in both DLBCL subtypes. Surprisingly, NFAT activation is independent of B-cell receptor signaling, but mediated by an increased calcium flux and calcineurin-mediated dephosphorylation of NFAT. Intriguingly, although NFAT is activated in both DLBCL subtypes, long-term calcineurin inhibition with cyclosporin A or FK506, both clinically approved drugs, triggers potent cytotoxicity specifically in ABC DLBCL cells. The antitumor effects of calcineurin inhibitors are associated with the reduced expression of c-Jun, interleukin-6, and interleukin-10, which were identified as NFAT target genes that are particularly important for the survival of ABC DLBCL. Furthermore, calcineurin blockade synergized with BCL-2 and MCL-1 inhibitors in killing ABC DLBCL cells. Collectively, these findings identify constitutive NFAT signaling as a crucial functional driver of ABC DLBCL and highlight calcineurin inhibition as a novel strategy for the treatment of this aggressive lymphoma subtype.
•DLBCL cell lines exhibit chronic NFAT activation, which is independent of B-cell receptor-mediated signals.•Long-term treatment of ABC DLBCL with calcineurin inhibitors induces cytotoxicity and synergizes with BCL-2 and MCL-1 inhibition.
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•BRD4 protects DLBCL cells from ferroptosis by positively regulating the expression of FSP1.•BET inhibitors increase the susceptibility of GCB-DLBCL cells to ferroptosis and thus promote the toxicity ...of DMF both in vitro and in vivo.
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Diffuse large B-cell lymphoma (DLBCL), the most common form of non-Hodgkin lymphoma, is characterized by an aggressive clinical course. In approximately one-third of patients with DLBCL, first-line multiagent immunochemotherapy fails to produce a durable response. Molecular heterogeneity and apoptosis resistance pose major therapeutic challenges in DLBCL treatment. To circumvent apoptosis resistance, the induction of ferroptosis might represent a promising strategy for lymphoma therapy. In this study, a compound library, targeting epigenetic modulators, was screened to identify ferroptosis-sensitizing drugs. Strikingly, bromodomain and extra-terminal domain (BET) inhibitors sensitized cells of the germinal center B-cell–like (GCB) subtype of DLBCL to ferroptosis induction and the combination of BET inhibitors with ferroptosis inducers, such as dimethyl fumarate or RSL3, synergized in the killing of DLBCL cells in vitro and in vivo. On the molecular level, the BET protein BRD4 was found to be an essential regulator of ferroptosis suppressor protein 1 expression and thus to protect GCB-DLBCL cells from ferroptosis. Collectively, we identified and characterized BRD4 as an important player in ferroptosis suppression in GCB-DLBCL and provide a rationale for the combination of BET inhibitors with ferroptosis-inducing agents as a novel therapeutic approach for DLBCL treatment.
First-line immunochemotherapy for diffuse large B-cell lymphoma (DLBCL) fails to produce a durable remission in about one-third of patients. Previous studies have suggested that the germinal center B-cell-like subset of DLBCL is sensitive to triggering of ferroptosis (iron-mediated cell death). Schmitt and colleagues screened a library of epigenetic modulators and demonstrate that bromodomain and extraterminal domain (BET) inhibitors enhance ferroptosis, suggesting the combination of BET inhibitors and ferroptosis-inducing agents as a novel therapy for DLBCL.
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