Exosomal miR-1246 from glioma patient body fluids drives the differentiation and activation of myeloid-derived suppressor cells

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Induction of myelodysplasia by myeloid-derived suppressor cells

Myelodysplastic syndromes (MDS) are age-dependent stem cell malignancies that share biological features of activated adaptive immune response and ineffective hematopoiesis. Here we report that myeloid-derived suppressor cells (MDSC), which are classically linked to immunosuppression, inflammation, and cancer, were markedly expanded in the bone marrow of MDS patients and played a pathogenetic role in the development of ineffective hematopoiesis. These clonally distinct MDSC overproduce hematopoietic suppressive cytokines and function as potent apoptotic effectors targeting autologous hematopoietic progenitors. Using multiple transfected cell models, we found that MDSC expansion is driven by the interaction of the proinflammatory molecule S100A9 with CD33. These 2 proteins formed a functional ligand/receptor pair that recruited components to CD33’s immunoreceptor tyrosine-based inhibition motif (ITIM), inducing secretion of the suppressive cytokines IL-10 and TGF-β by immature myeloid cells. S100A9 transgenic mice displayed bone marrow accumulation of MDSC accompanied by development of progressive multilineage cytopenias and cytological dysplasia. Importantly, early forced maturation of MDSC by either all-trans-retinoic acid treatment or active immunoreceptor tyrosine-based activation motif–bearing (ITAM-bearing) adapter protein (DAP12) interruption of CD33 signaling rescued the hematologic phenotype. These findings indicate that primary bone marrow expansion of MDSC driven by the S100A9/CD33 pathway perturbs hematopoiesis and contributes to the development of MDS.     

Inhibition of dendritic cell differentiation and accumulation of myeloid-derived suppressor cells in cancer is regulated by S100A9 protein

Accumulation of myeloid-derived suppressor cells (MDSCs) associated with inhibition of dendritic cell (DC) differentiation is one of the major immunological abnormalities in cancer and leads to suppression of antitumor immune responses. The molecular mechanism of this phenomenon remains unclear. We report here that STAT3-inducible up-regulation of the myeloid-related protein S100A9 enhances MDSC production in cancer. Mice lacking this protein mounted potent antitumor immune responses and rejected implanted tumors. This effect was reversed by administration of wild-type MDSCs from tumor-bearing mice to S100A9-null mice. Overexpression of S100A9 in cultured embryonic stem cells or transgenic mice inhibited the differentiation of DCs and macrophages and induced accumulation of MDSCs. This study demonstrates that tumor-induced up-regulation of S100A9 protein is critically important for accumulation of MDSCs and reveals a novel molecular mechanism of immunological abnormalities in cancer.     

Phosphodiesterase-5 inhibition augments endogenous antitumor immunity by reducing myeloid-derived suppressor cell function

Phosphodiesterase-5 (PDE5) inhibitors (sildenafil, tadalafil, and vardenafil) are agents currently in clinical use for nonmalignant conditions. We report the use of PDE5 inhibitors as modulators of the antitumor immune response. In several mouse tumor models, PDE5 inhibition reverses tumor-induced immunosuppressive mechanisms and enables a measurable antitumor immune response to be generated that substantially delays tumor progression. In particular, sildenafil, down-regulates arginase 1 and nitric oxide synthase-2 expression, thereby reducing the suppressive machinery of CD11b+/Gr-1+ myeloid-derived suppressor cells (MDSCs) recruited by growing tumors. By removing these tumor escape mechanisms, sildenafil enhances intratumoral T cell infiltration and activation, reduces tumor outgrowth, and improves the antitumor efficacy of adoptive T cell therapy. Sildenafil also restores in vitro T cell proliferation of peripheral blood mononuclear cells from multiple myeloma and head and neck cancer patients. In light of the recent data that enzymes mediating MDSC-dependent immunosuppression in mice are active also in humans, these findings demonstrate a potentially novel use of PDE5 inhibitors as adjuncts to tumor-specific immune therapy.     

髓源性抑制细胞在类风湿关节炎中的研究进展

髓源性抑制细胞(MDSCs)是一群免疫异质性细胞,通常在肿瘤、慢性炎症和骨髓移植等病理状态下出现扩增,在机体免疫系统中起调节作用。对MDSCs的研究早期集中在肿瘤方面,近年来对自身免疫性疾病研究逐渐增多。本文综述MDSCs的来源、不同分型功能、作用机制及与类风湿关节炎关系的相关研究。     

Hepatic acute-phase proteins control innate immune responses during infection by promoting myeloid-derived suppressor cell function

Acute-phase proteins (APPs) are an evolutionarily conserved family of proteins produced mainly in the liver in response to infection and inflammation. Despite vast pro- and antiinflammatory properties ascribed to individual APPs, their collective function during infections remains poorly defined. Using a mouse model of polymicrobial sepsis, we show that abrogation of APP production by hepatocyte-specific gp130 deletion, the signaling receptor shared by IL-6 family cytokines, strongly increased mortality despite normal bacterial clearance. Hepatic gp130 signaling through STAT3 was required to control systemic inflammation. Notably, hepatic gp130–STAT3 activation was also essential for mobilization and tissue accumulation of myeloid-derived suppressor cells (MDSCs), a cell population mainly known for antiinflammatory properties in cancer. MDSCs were critical to regulate innate inflammation, and their adoptive transfer efficiently protected gp130-deficient mice from sepsis-associated mortality. The hepatic APPs serum amyloid A and Cxcl1/KC cooperatively promoted MDSC mobilization, accumulation, and survival, and reversed dysregulated inflammation and restored survival of gp130-deficient mice. Thus, gp130-dependent communication between the liver and MDSCs through APPs controls inflammatory responses during infection.Sepsis is a major cause of mortality worldwide characterized by a dysregulated inflammatory response to infection (Hotchkiss and Karl, 2003). Excessive inflammation accounts for serious complications, but unfortunately, strategies targeting key proinflammatory mediators have had only very limited success (Fisher et al., 1996; Riedemann et al., 2003), demonstrating the complex pathogenesis of the disorder that is determined by a variety of both pathogen and host factors. Notably, patients with chronic liver diseases have significantly increased risk of acquiring sepsis and its accompanying complications, and thus have higher sepsis-related mortality, with it accounting for 30% of all deaths in cirrhotic patients (Foreman et al., 2003). The underlying mechanisms for this clinical observation are only partially understood.The liver is the major source of acute-phase proteins (APPs), which are defined as proteins whose serum levels change by >25% during inflammation (Gabay and Kushner, 1999), and they are regarded as important components of the innate immune response to infection (Medzhitov, 2007). Many APPs are known as potent opsonins (Shah et al., 2006) and activators of innate immune cells such as neutrophils (Cheng et al., 2008a), but they also have antiinflammatory properties (Zouki et al., 1997). Because of the large diversity of APPs with both pro- and antiinflammatory functions (Gabay and Kushner, 1999), their overall role during infections is still not well defined.IL-6 is widely viewed as the major inducer of APP production in hepatocytes (Ritchie and Fuller, 1983). However, APP production in IL-6–deficient mice is only partly impaired and varies depending on the stimulus (Kopf et al., 1994). This strongly suggests redundant functions of the IL-6 family cytokines, a large group of cytokines that share the common signaling receptor gp130 (Murakami et al., 1993), or compensatory APP induction by other cytokines such as TNF and IL-1β. Most IL-6 cytokines bind to a membrane-bound cognate receptor and form a signaling complex with two gp130 receptors. Phosphorylation of distinct tyrosines of the intracellular domains of gp130 leads to activation of STAT3 and/or Ras–mitogen-activated protein kinase (MAPK) signaling. To better define the function of the hepatic acute-phase response during sepsis and endotoxic shock, we investigated the role of gp130 and downstream intracellular signaling pathways in hepatocytes. Although local effects of hepatic gp130 deficiency have been well characterized (Klein et al., 2005), systemic consequences remain unknown.Innate immune cell activation is critical for host defense against invading microorganisms and for the subsequent generation of an adaptive immune response (Medzhitov, 2007). On the other hand, proinflammatory mediators produced by innate immune cells are considered key elements in the pathogenesis of severe sepsis and multiorgan failure (Rittirsch et al., 2008). Tight control of proinflammatory pathways is therefore critical for immune homeostasis and host survival. A complex network of activating and regulatory pathways controls innate immune responses. In this study, we postulated that the hepatic acute-phase response crucially contributes to this regulation. Because one of the major proinflammatory mediators in sepsis, IL-6, is known to be a strong stimulator of APP production in the liver, we hypothesized that the resulting acute-phase response potentially acts as a counterregulator of the initial inflammatory reaction. We investigated whether hepatic APPs affect the central and peripheral immune cell composition, which undergoes dramatic changes during infections and endotoxemia. Interestingly, a growing body of evidence highlights the capacity of myeloid-derived suppressor cells (MDSCs), a heterogeneous, immature population of myeloid (precursor) cells characterized by the expression of the myeloid lineage marker Gr1 and CD11b, to inhibit T cell responses (Movahedi et al., 2008; Gabrilovich and Nagaraj, 2009). Although MDSCs are best known and characterized for their role in tumor immune evasion and promotion of metastasis (Nagaraj et al., 2007; Yang et al., 2008), they have also been associated with other pathological conditions like trauma, inflammation, and autoimmune disease (Zhu et al., 2007; Haile et al., 2008). Moreover, it has been reported that MDSCs accumulate in the spleens of mice during polymicrobial sepsis and suppress T cell functions (Delano et al., 2007). However, to which extent MDSCs modify the course of disease or if they critically contribute to immune regulation during sepsis remains unclear.In the present study we find that gp130–STAT3 signaling in hepatocytes and subsequent APP production is required to control the inflammatory response by facilitating peripheral accumulation and survival of MDSCs in sepsis. We provide evidence that MDSCs can directly inhibit inflammatory immune responses and define them as a key autoregulatory component of the innate immune system during infection.     

Eugenol triggers CD11b+Gr1+ myeloid-derived suppressor cell apoptosis via endogenous apoptosis pathway

To study the effect and underlying molecular mechanism of eugenol on CD11b⁺Gr1⁺ myeloid-derived suppressor cells (MDSCs). The effect of eugenol on the inhibition of immortalized MDSC cell line MSC-2 and murine peritoneal macrophages was detected by MTT. Flow cytometry was used to detect the pro-apoptosis effect of eugenol on MDSCs. The expression levels of apoptosis-related proteins were detected by western blot. Eugenol has a selective inhibitory effect on MDSCs in a dose-dependent manner, which activates an endogenous apoptosis pathway, leading to apoptosis. Eugenol promotes the apoptosis of MDSCs via the intrinsic pathway.

To study the effect and underlying molecular mechanism of eugenol on CD11b⁺Gr1⁺ myeloid-derived suppressor cells (MDSCs).     

髓源性抑制细胞与肝病免疫作用机制研究进展

髓源性抑制细胞(MDSCs)是一群未分化完全的、具有免疫抑制功能的、骨髓源性异质细胞群,MDSCs在肿瘤中的免疫抑制作用是目前研究的热点.近年来,关于MDSCs在许多非肿瘤疾病中的免疫抑制作用的研究日益增多.了解髓源性抑制细胞的免疫机制有重要的意义.     

STAT3 regulates arginase-I in myeloid-derived suppressor cells from cancer patients

Myeloid-derived suppressor cells (MDSC) play a key immunosuppressive role in various types of cancer, including head and neck squamous cell carcinoma (HNSCC). In this study, we characterized CD14⁺HLA-DR^–/lo cells sorted from the tumors, draining lymph nodes, and peripheral blood of HNSCC patients. CD14⁺HLA-DR^–/lo cells were phenotyped as CD11b⁺, CD33⁺, CD34⁺, arginase-I⁺, and ROS⁺. In all 3 compartments, they suppressed autologous, antigen-independent T cell proliferation in a differential manner. The abundance of MDSC correlated with stage, but did not correlate with previous treatment with radiation or subsites of HNSCC. Interestingly, MDSC from all 3 compartments showed high phosphorylated STAT3 levels that correlated with arginase-I expression levels and activity. Stattic, a STAT3-specific inhibitor, and STAT3-targeted siRNA abrogated MDSC’s suppressive function. Inhibition of STAT3 signaling also resulted in decreased arginase-I activity. Analysis of the human arginase-I promoter region showed multiple STAT3-binding elements, and ChIP demonstrated that phosphorylated STAT3 binds to multiple sites in the arginase-I promoter. Finally, rescue of arginase-I activity after STAT3 blockade restored MDSC’s suppressive function. Taken together, these results demonstrate that the suppressive function of arginase-I in both infiltrating and circulating MDSC is a downstream target of activated STAT3.     

髓样来源抑制性细胞在消化系统非肿瘤性疾病中的研究进展

髓样来源抑制性细胞(MDSCs)是高度异质性的细胞亚群,可扰乱内源性和适应性免疫,在许多疾病过程中发挥重要的作用。最初对MDSCs的认识主要是从对肿瘤的研究中得到的。近年来MDSCs在众多非肿瘤疾病中的作用引起了广泛关注并逐渐得到证实。本文主要就目前MDSCs在各类消化系统非肿瘤疾病中的研究进行综述。     

Tumor-induced myeloid deviation: when myeloid-derived suppressor cells meet tumor-associated macrophages

The generation of an inflammatory environment is favorable and often decisive for the growth of both primary tumors and metastases. Tumor cells either express membrane molecules or release tumor-derived soluble factors able to alter myelopoiesis. Tumor-reprogrammed myeloid cells not only create a tolerogenic environment by blocking T cell functions and proliferation, but also directly drive tumor growth by promoting cancer stemness, angiogenesis, stroma deposition, epithelial-to-mesenchymal transition, and metastasis formation. In this Review, we discuss the interplay between immunosuppressive and protumoral myeloid cells and detail their immune-regulatory mechanisms, the molecular pathways involved in their differentiation, as well as their potential role as prognostic and diagnostic biomarkers and prospective targets for innovative approaches to treat tumor-bearing hosts.Tumor progression depends on the gradual accumulation of genetic and epigenetic aberrations in cancer cells that also modify the cellular composition of the tumor environment, establishing a state of chronic inflammation characterized by the stromal infiltration of immune cells. Myeloid cells play a critical role in sustaining cancer progression (1). Moreover, inflammatory myeloid cells help to create and fuel the mutagenic pressure underlying the genetic instability of neoplastic cells by both direct mechanisms, such as the production of free-radical compounds (2), and indirect processes, such as the disruption of host defense barriers (3).Tumor growth is assisted by tumor-associated macrophages (TAMs), the major leukocyte population infiltrating cancers (4). Although macrophages have the potential to attack and eliminate tumor cells, TAMs exhibit many protumoral features that are partly shared by macrophages involved in tissue repair, and they interfere with the function and proliferation of immune effectors (5). Thus, a high frequency of TAMs is associated with poor prognosis in many but not all human tumors (6).Myeloid-derived suppressor cells (MDSCs) have received increased attention, and their presence and frequency in the blood of patients with tumors is emerging as a potential and simple prognostic marker to monitor clinical outcome and response to therapy (7). MDSCs are characterized by their myeloid origin, heterogeneous cell composition, and ability to negatively regulate adaptive and innate immune responses to cancer. Although TAMs and MDSCs are regarded as separate entities (Figure 1), the boundaries between them are not clearly demarcated, and they share many characteristics (8). TAM accumulation in cancerous tissues is sustained by circulating inflammatory monocytes (CCR2⁺Ly6C⁺ cells in mice and CCR2⁺CD14⁺CD16^– cells in humans; ref. 9), which are distinct from vessel-patrolling monocytes (Ly6C^loCX3CR1^hi in mice and CD14^dimCD16^–CX3CR1^hi in humans). Interestingly, immunosuppressive MDSCs with monocytic features are able to traffic from BM to tumors, mainly through the same chemokine pathway (10). Therefore, the CCR2/CCL2 axis is required for MDSC and TAM accrual and functional specialization. Here, we review the distinctive and common characteristics of TAMs and MDSCs, their role in maintaining cancer growth, and the ongoing development of selective therapeutic approaches.Open in a separate windowFigure 1Common phenotypic markers of MDSCs and TAMs.Several phenotypic markers of mouse and human MDSCs (A) and TAMs (B) have been identified (+ indicates expression, while – indicates lack of expression) and used to define specific cell subgroups, such as PMN-MDSCs, MO-MDSCs, and immature MDSCs (I-MDSCs), as well as M1-like and M2-like TAMs, by both cytofluorimetric and immunohistochemical analyses.     

Polyamines from myeloid-derived suppressor cells promote Th17 polarization and disease progression

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Silymarin suppressed lung cancer growth in mice via inhibiting myeloid-derived suppressor cells

In this study, we investigated the antitumor activity of Silymarin in a mouse model of colon cancer xenograft of Lewis lung cancer (LLC) cells. Silymarin significantly suppressed tumor growth and induced apoptosis of cells in tumor tissues at a dose of 25 and 50 mg/kg. Silymarin treatment enhanced the infiltration and function of CD8⁺ T cells. In the meantime, Silymarin decreased the level of IL-10 while elevated the level of IL-2 and IFN-γ in the serum of tumor-bearing mice. Finally, Silymarin reduced the proportion of myeloid-derived suppressor cells (MDSC) in the tumor tissue and also the mRNA expressions of inducible nitric oxide synthases-2 (iNOS2), arginase-1 (Arg-1) and MMP9, which indicated that the function of MDSC in tumor tissues were suppressed. Altogether, our data here showed that Silymarin inhibited the MDSC and promoted the infiltration and function of CD8⁺ T cells thus suppressed the growth of LLC xenografts, which provides evidence for the possible use of Silymarin against lung cancer.     

创伤后多器官功能障碍综合征患者外周血髓源抑制细胞细胞的表达

目的探讨创伤后多器官功能障碍综合征(MODS)患者外周血髓源抑制细胞(MDSCs)的表达在诊断MODS疾病严重程度和预后判断中的临床意义。方法分别采集66例MODS患者、78例非MODS患者和37例健康志愿者外周血,以CD14-CD11b+CD33+作为MDSCs的标志,采用流式细胞术检测MDSCs细胞的表达;以MODS评分评估疾病严重程度;采用酶联免疫吸附法(ELISA)测定血清白细胞介素-10(IL-10)和肿瘤坏死因子-α(TNF-α)水平,并分析患者MDSCs的表达与疾病严重程度评分和IL-10和TNF-α水平的相关性。结果 MODS患者外周血CD14-CD11b+CD33+细胞表达为(11.84±2.18)%明显高于非MODS组的(6.52±0.37)%和健康对照组的(1.18±0.22)%(P0.05);MODS患者死亡组(15.66±1.68)%较存活组(9.48±1.56)%明显升高(P0.05)。MODS患者血清IL-10、TNF-α水平较非MODS组和健康对照组明显增高(P0.05)。MODS患者中死亡组血清IL-10、TNF-α水平较存活组明显升高(P0.05);相关分析显示,MODS患者外周血CD14-CD11b+CD33+细胞表达率与TNF-α水平和MODS评分成正相关(r分别为0.342 6、0.387 9,P0.05)。结论外周血MDSCs水平变化可能与疾病的严重程度和预后相关。     

Distinct mechanisms govern populations of myeloid-derived suppressor cells in chronic viral infection and cancer

Myeloid-derived suppressor cells (MDSCs) are major negative regulators of immune responses in cancer and chronic infections. It remains unclear if regulation of MDSC activity in different conditions is controlled by similar mechanisms. We compared MDSCs in mice with cancer and lymphocytic choriomeningitis virus (LCMV) infection. Chronic LCMV infection caused the development of monocytic MDSCs (M-MDSCs) but did not induce polymorphonuclear MDSCs (PMN-MDSCs). In contrast, both MDSC populations were present in cancer models. An acquisition of immune-suppressive activity by PMN-MDSCs in cancer was controlled by IRE1α and ATF6 pathways of the endoplasmic reticulum (ER) stress response. Abrogation of PMN-MDSC activity by blockade of the ER stress response resulted in an increase in tumor-specific immune response and reduced tumor progression. In contrast, the ER stress response was dispensable for suppressive activity of M-MDSCs in cancer and LCMV infection. Acquisition of immune-suppressive activity by M-MDSCs in spleens was mediated by IFN-γ signaling. However, it was dispensable for suppressive activity of M-MDSCs in tumor tissues. Suppressive activity of M-MDSCs in tumors was retained due to the effect of IL-6 present at high concentrations in the tumor site. These results demonstrate disease- and population-specific mechanisms of MDSC accumulation and the need for targeting different pathways to achieve inactivation of these cells.     

Bring on the brequinar: an approach to enforce the differentiation of myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) hinder antitumor immunity in multiple cancer types. While brequinar (BRQ), an inhibitor of dihydroorotate dehydrogenase, shows cytotoxicity in hematological malignancy, it has not yet been adapted to attenuate MDSCs by augmenting bone marrow progenitors in breast cancer. In this issue of the JCI, Colligan et al. demonstrate that BRQ restored terminal differentiation of MDSCs. Using in vivo models of immunotherapy-resistant breast cancer, the authors uncovered a mechanism by which BRQ promoted myeloid cell differentiation by limiting their suppressive function and enhancing the efficacy of immune checkpoint blockade therapy. The findings offer insight into the biogenesis of MDSCs, provide an alternative avenue for cancers that remain unresponsive to conventional therapies, and may be extended to future translational studies in patients.     

细胞因子信号转导抑制因子（SOCS）与免疫调节

细胞因子信号转导抑制因子（suppressor of cytokine signaling,SOCS）是一类可由多种细胞因子诱导产生,又能通过多种途径对细胞因子的信号转导进行负向调节的蛋白质分子。众多研究发现SOCS蛋白家族是一个非常重要的可以负向调节 JAK／STAT信号通路的分子家族。本文将着重阐述介绍SOCS家族在炎症和自身免疫性疾病中的作用。     

DUSP4 deficiency caused by promoter hypermethylation drives JNK signaling and tumor cell survival in diffuse large B cell lymphoma

The epigenetic dysregulation of tumor suppressor genes is an important driver of human carcinogenesis. We have combined genome-wide DNA methylation analyses and gene expression profiling after pharmacological DNA demethylation with functional screening to identify novel tumor suppressors in diffuse large B cell lymphoma (DLBCL). We find that a CpG island in the promoter of the dual-specificity phosphatase DUSP4 is aberrantly methylated in nodal and extranodal DLBCL, irrespective of ABC or GCB subtype, resulting in loss of DUSP4 expression in 75% of >200 examined cases. The DUSP4 genomic locus is further deleted in up to 13% of aggressive B cell lymphomas, and the lack of DUSP4 is a negative prognostic factor in three independent cohorts of DLBCL patients. Ectopic expression of wild-type DUSP4, but not of a phosphatase-deficient mutant, dephosphorylates c-JUN N-terminal kinase (JNK) and induces apoptosis in DLBCL cells. Pharmacological or dominant-negative JNK inhibition restricts DLBCL survival in vitro and in vivo and synergizes strongly with the Bruton’s tyrosine kinase inhibitor ibrutinib. Our results indicate that DLBCL cells depend on JNK signaling for survival. This finding provides a mechanistic basis for the clinical development of JNK inhibitors in DLBCL, ideally in synthetic lethal combinations with inhibitors of chronic active B cell receptor signaling.Diffuse large B cell lymphoma (DLBCL) is the most commonly diagnosed lymphoma in adults. It may either arise de novo at nodal or extranodal sites or as a consequence of malignant transformation of indolent lymphomas or leukemias such as follicular lymphoma (FL), chronic lymphocytic leukemia (CLL), and marginal zone lymphoma (MZL; Schneider et al., 2011; Shaffer et al., 2012; Pasqualucci and Dalla-Favera, 2014). DLBCL represents a heterogeneous disease, with molecular subtypes being characterized by distinct gene expression profiles, specific sets of somatic mutations, and differentially active intracellular signaling pathways (Roschewski et al., 2014). Three subtypes of DLBCL can be distinguished based on the presumed normal B cell counterpart, with activated B cell–like DLBCL (ABC-DLBCL) resembling the post–germinal center (GC) plasmablast, GC B cell–like DLBCL (GCB-DLBCL) deriving from GC B cells, and primary mediastinal B cell lymphoma (PMBL) arising in the thymus from a rare subset of thymic B cells (Alizadeh et al., 2000; Rosenwald et al., 2003). The three subtypes of DLBCL differ not only in their pathogenesis, but also in their cure and survival rates (Cultrera and Dalia, 2012). The rational development of more targeted therapies is complicated by the heterogeneity of DLBCL as well as the coexistence of genetic lesions affecting multiple redundant survival pathways. Genetic aberrations in DLBCL either exclusively affect GCB-DLBCL (deregulated c-Myc or Bcl-2 expression, gain of function of the H3K27 methyltransferase EZH2) or ABC-DLBCL (A20 loss, gain of function of MYD88, CD79A/B, or CARD11, all of which promote the constitutive activation of the NF-κB pathway) or are found in both major subtypes (inactivating mutations and deletions in the histone acetyltransferases CBP and p300 as well as the histone methyl transferase MLL2; Schneider et al., 2011; Shaffer et al., 2012; Pasqualucci and Dalla-Favera, 2014).Aberrant changes of the DNA methylation landscape are a hallmark of cancer cells and have been linked to clinical aggressiveness and chemoresistance of DLBCL (Shaknovich et al., 2010; Clozel et al., 2013; De et al., 2013; Chambwe et al., 2014). Examples of tumor suppressor genes known to be silenced by promoter hypermethylation in DLBCL include SMAD1, MGMT, CDKN2A, and the lamin A/C gene (Martinez-Delgado et al., 1997; Esteller et al., 2002; Agrelo et al., 2005; Clozel et al., 2013). We have shown in earlier studies that the epigenetic silencing of the tumor suppressor microRNAs miR-203 and miR-34a contribute to the transformation of gastric MZL to DLBCL and to the deregulated expression of the hematopoietic oncoprotein FoxP1 (Craig et al., 2011a,b). Here, we have conducted a genome-wide analysis of the DNA methylome of gastric DLBCL and MZL and of nodal DLBCL samples and cell lines. The hypermethylated gene loci were further examined by RNA sequencing with respect to their reactivation upon experimental DNA demethylation. Aberrantly silenced genes were ectopically expressed in DLBCL cell lines and assessed for possible effects on cell survival. This unbiased approach uncovered a new tumor suppressor in DLBCL, the dual-specificity phosphatase DUSP4, and introduces the constitutively active JNK signaling pathway as a promising new target in DLBCL treatment.