[Show abstract][Hide abstract] ABSTRACT: Genome-wide association studies (GWASs) have identified several single-nucleotide polymorphisms (SNPs) influencing the risk of Hodgkin's lymphoma (HL) and demonstrated the association of common genetic variation for this type of cancer. Such evidence for inherited genetic risk is also provided by the family history and the very high concordance between monozygotic twins. However, little is known about the genetic and environmental contributions. A common measure for describing the phenotypic variation due to genetics is the heritability. Using GWAS data on 906 HL cases by considering all typed SNPs simultaneously, we have calculated that the common variance explained by SNPs accounts for >35% of the total variation on the liability scale in HL (95% confidence interval 6-62%). These findings are consistent with similar heritability estimates of ∼0.40 (95% confidence interval 0.17-0.58) based on Swedish population data. Our estimates support the underlying polygenic basis for susceptibility to HL, and show that heritability based on the population data is somehow larger than heritability based on the genomic data because of the possibility of some missing heritability in the GWAS data. Besides that there is still major evidence for multiple loci causing HL on chromosomes other than chromosome 6 that need to be detected. Because of limited findings in prior GWASs, it seems worth checking for more loci causing susceptibility to HL.European Journal of Human Genetics advance online publication, 17 September 2014; doi:10.1038/ejhg.2014.184.
European journal of human genetics: EJHG 09/2014; · 3.56 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Natural killer (NK) cells are potent immune effector cells capable of mediating antitumor responses. Thus, during immunoediting tumor cell populations evolve strategies to escape NK cell-mediated recognition. In this study, we report a novel mechanism of immune escape involving tumor cell shedding of B7-H6, a ligand for the activating receptor NKp30 that mediates NK cell binding and NK cell-mediated killing, Tumor cells from different cancer entities released B7-H6 by ectodomain shedding mediated by the cell surface proteases ADAM-10 and ADAM-17, as demonstrated through the use of pharmacological inhibitors or siRNA-mediated gene attenuation. Inhibiting this proteolytic shedding process increased the levels of B7-H6 expressed on the surface of tumor cells, enhancing NKp30-mediated activation of NK cells. Notably, we documented elevated levels of soluble B7-H6 levels in blood sera obtained from a subset of malignant melanoma patients, compared to healthy control individuals, along with evidence of elevated B7-H6 expression in melanoma specimens in situ. Taken together, our results illustrated a novel mechanism of immune escape in which tumor cells impede NK-mediated recognition by metalloprotease-mediated shedding of B7-H6. One implication of our findings is that therapeutic inhibition of specific metalloproteases may help support NK cell-based cancer therapy.
[Show abstract][Hide abstract] ABSTRACT: Exosomes are endosomal-derived nanovesicles released by normal and tumor cells, which transfer functionally active proteins, lipids, and nucleic acids between cells. They are important mediators of intercellular communication and act on the adjacent stroma as well as in the periphery. Recently, exosomes have been recognized to play a pathophysiological role in various diseases such as cancer or infectious diseases. Tumor cell-derived exosomes (Tex) have been shown to act as tumor promotors by educating non-malignant cells to provide a tumor supporting microenvironment, which helps to circumvent immune detection by the host and supports metastasis. However, Tex with anti-tumor, immune-activating properties were also described reflecting the complexity of exosomes. Here, we assess the role of extracellular microvesicles/exosomes as messengers affecting NK cell function in health and disease and discuss the molecular basis for the differential impact of exosomes on NK cell activity. The molecular composition/load of exosomes and the mechanisms regulating their release remain unclear and need to be further analyzed to facilitate the development of new treatment options targeting the exosomal machinery.
[Show abstract][Hide abstract] ABSTRACT: The insight that the immune system is able to eradicate tumor cells inspired the development of targeted immunotherapies. These novel approaches aim to trigger immune molecules and receptors, including CD3 on T cells and NKG2D and NKp30 on natural killer (NK) cells, to harness the immune system against cancer. In cancer patients, overcoming immune suppression induced by malignant cells or by the tumor microenvironment remains the major challenge to the clinical efficacy of immunotherapies. Recombinant constructs have been developed in various formats either utilizing natural ligands (immunoligands) or antibody-derived components (immunoconstructs) to circumvent mechanisms that counteract an effective antitumor immune response.
Trends in Molecular Medicine 11/2013; · 9.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In addition to HLA, recent genome-wide association studies (GWASs) of Hodgkin's lymphoma (HL) have identified susceptibility loci for HL at 2p16.1, 8q24.21 and 10p14. In this study, we perform a GWAS meta-analysis with published GWAS (totalling 1,465 cases and 6,417 controls of European background), and follow-up the most significant association signals in 2,024 cases and 1,853 controls. A combined analysis identifies new HL susceptibility loci mapping to 3p24.1 (rs3806624; P=1.14 × 10(-12), odds ratio (OR)=1.26) and 6q23.3 (rs7745098; P=3.42 × 10(-9), OR=1.21). rs3806624 localizes 5' to the EOMES (eomesodermin) gene within a p53 response element affecting p53 binding. rs7745098 maps intergenic to HBS1L and MYB, a region previously associated with haematopoiesis. These findings provide further insight into the genetic and biological basis of inherited susceptibility to HL.
[Show abstract][Hide abstract] ABSTRACT: Abstract Evasion of apoptosis is a hallmark of cancer cells. Inhibitor of apoptosis proteins (IAPs) act as endogenous inhibitors of programmed cell death and are overexpressed in several tumors including Hodgkin lymphoma (HL). Preclinical studies indicate antitumor activity of IAP antagonists and clinical studies in hematological malignancies are underway. Here, we investigate the impact of the small molecule IAP antagonist LCL161 on HL cell lines. Although the antagonist caused rapid degradation of cIAP1 leading to TNFα secretion, LCL161 did not promote apoptosis significantly. However, LCL161 induced expression of MICA and MICB, ligands for the activating immune receptor NKG2D, and enhanced the susceptibility of HL cells to NKG2D-dependent lysis by NK cells. MICA/B upregulation was dependent on activation of the DNA damage response upon LCL161 treatment. Taken together, we demonstrate a novel link between IAP inhibition, DNA damage and immune recognition.
[Show abstract][Hide abstract] ABSTRACT: Natural killer (NK) cells are able to lyse infected and tumor cells while sparing healthy cells. Recognition of diseased cells by NK cells is governed by several activating and inhibitory receptors. We review numerous pathways that have been implicated in the regulation of self-ligands for activating receptors, including NKG2D, DNAM-1, LFA-1, NKp30, NKp44, NKp46, NKp65, and NKp80 found on NK cells and some T cells. Understanding how the regulation of self-encoded ligand expression is regulated may provide novel avenues for future therapeutic approaches to infections and cancer.
[Show abstract][Hide abstract] ABSTRACT: Key points Exosomal NKp30-ligand BAG6 is crucial for detection of tumor cells by NK cells in vitro and in vivo.Soluble plasma factors including BAG6 suppress NK cell cytotoxicity and promote evasion of CLL cells from NK cell anti-tumor activity.
[Show abstract][Hide abstract] ABSTRACT: Natural killer (NK) cells represent a key component of the innate immune system against cancer. Nevertheless, malignant diseases arise in immunocompetent individuals despite tumor immunosurveillance. Hodgkin lymphoma (HL) is characterized by CD30+ tumor cells and a massive infiltration of immune effector cells in affected lymph nodes. The latter obviously fail to eliminate the malignant cell population. Here, we tested for functional NK cell defects in HL and suggest an improvement of NK function by therapeutic means. We demonstrate that peripheral NK cells (pNK) from patients with HL fail to eliminate HL cell lines in ex vivo killing assays. Impaired NK cell function correlated with elevated serum levels of soluble ligands for NK cell receptors NKp30 (BAG6/BAT3) and NKG2D (MICA), factors known to constrict NK cell function. In vitro, NK cell cytotoxicity could be restored by an NKG2D/NKp30-independent bispecific antibody construct (CD30xCD16A). It artificially links the tumor receptor CD30 with the cytotoxicity NK cell receptor CD16A. Moreover, we observed that NK cells from patients treated with this construct were generally activated and displayed a restored cytotoxicity against HL target cells. These data suggest that reversible suppression of NK cell activity contributes to immune evasion in HL and can be antagonized therapeutically.Molecular Therapy (2013); doi:10.1038/mt.2013.14.
[Show abstract][Hide abstract] ABSTRACT: Galectin-1 (Gal1) is a member of a highly conserved family of carbohydrate-binding proteins that modulates innate and adaptive immune responses and fosters tumor-immune escape. Hodgkin lymphoma (HL) Reed-Sternberg (RS) cells overexpress and secrete Gal1, which selectively kills Th1, Th17 and cytotoxic T cells and promotes the immunosuppressive Th2/Treg-predominant HL microenvironment. We developed a sandwich ELISA and assessed serum Gal1 levels in 293 newly diagnosed, previously untreated classical HL (cHL) patients enrolled on 3 risk-adapted clinical trials. Serum Gal1 levels were significantly higher in cHL patients than in normal controls (p < .0001). Gal1 serum levels also increased with Ann Arbor stage (p = .012), areas of nodal involvement (p < .0001) and the International Prognostic Score (IPS) (2-7, p = .019). We conclude that Gal1 serum levels are significantly associated with tumor burden and associated clinical features in newly diagnosed cHL patients.
[Show abstract][Hide abstract] ABSTRACT: Natural killer (NK) cells are a major component of the antitumor immune response. NK cell dysfunctions have been reported in various hematological malignancies, including chronic lymphocytic leukemia (CLL). Here we investigated the role of tumor cell-released soluble and exosomal ligands for NK cell receptors that modulate NK cell activity. Soluble CLL plasma factors suppressed NK cell cytotoxicity and down-regulated the surface receptors CD16 and CD56 on NK cells of healthy donors. The inhibition of NK cell cytotoxicity was attributed to the soluble NKp30 ligand BAG6/BAT3, detectable in the plasma of CLL patients, with the highest levels at advanced disease stages. In contrast, NK cells were activated by BAG6 expressed on exosomes. Exosomal BAG6 expression was induced by cellular stress via an nSMase2-dependent pathway. Finally, cells releasing exosomal BAG6 were eliminated by lymphocytes in a xenograft tumor model in vivo; in marked contrast BAG6-deficient cells that failed to produce exosomal BAG6 evaded immune detection. Taken together, the findings show that the dysregulated balance of exosomal versus soluble BAG6 expression may causes immune evasion of CLL cells.
[Show abstract][Hide abstract] ABSTRACT: Epigenetic changes have been implicated in the malignant phenotype of Hodgkin Reed Sternberg (HRS) cells in Hodgkin lymphoma (HL), where HRS survival and proliferation depends on the microenvironment. The histone-deacetylase (HDAC) inhibitor LBH589 (panobinostat) showed clinical efficacy but its impact on the HRS microenvironment is unclear. Hence, we analysed the effects of LBH589 on lymphocytes and also potential combination therapies. In lymphocyte-target cell killing assays, LBH589-treatment triggered an enhanced lymphocyte-dependent lysis of HL cells despite of mild lymphocytopenic effects. In co-culture experiments of lymphocytes with HL cells, LBH589 suppressed the IFNgamma-release but increased the TNFalpha secretion. Recombinant TNFalpha boosted the lymphocyte-dependent lysis of HL target cells. In HL cell lines, LBH589 induced cell death, autophagy, and an increase of MICA/B that are ligands to natural killer cell receptors. The combination of LBH589 with Brentuximab Vedotin was inefficient due to down-regulation of CD30 as a target. Combination with gemcitabine revealed highly significant effects, suggesting a potential combination for future therapy. Based on these data we suggest that LBH589 favourably modulates the cytokine network and lymphocyte activity in the HL microenvironment.
PLoS ONE 01/2013; 8(11):e79502. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Survival of chronic lymphocytic leukemia (CLL) cells depends on stimuli provided by a suitable microenvironment. The factors and mechanisms providing this growth support for CLL cells are not fully understood. We found that plasma levels of macrophage migration inhibitory factor (MIF), a pro-inflammatory and immunoregulatory chemokine, were elevated in CLL patients. Therefore, we characterized the functional role of MIF in a CLL mouse model. For this purpose, we crossed Eμ-TCL1 mice with MIF knockout (MIF(-/-)) mice. The resulting TCL1(+/wt)MIF(-/-) mice showed a delayed onset of leukemia, reduced splenomegaly and hepatomegaly and a longer survival than TCL1(+/wt)MIF(wt/wt) controls. Immunohistochemical examination of the lymphoid organs showed that the numbers of macrophages were significantly reduced in the spleen and bone marrow of TCL1(+/wt)MIF(-/-) mice compared to TCL1(+/wt)MIF(wt/wt) controls. Mechanistic studies in vitro revealed that the absence of MIF rendered CLL cells more susceptible to apoptosis. Accordingly, incubation with an anti-MIF antibody reduced the survival of CLL cells on a macrophage feeder layer. In addition, the migratory activity of TCL1(+/wt)MIF(-/-) macrophages was decreased compared to TCL1(+/wt)MIF(wt/wt) macrophages. Taken together, our results provide evidence that MIF supports the development of CLL by enhancing the interaction of CLL cells with macrophages.
[Show abstract][Hide abstract] ABSTRACT: The interplay between dendritic cells (DCs) and natural killer (NK) cells directs adaptive immune responses. The molecular basis of the cross-talk is largely undefined. Here, we provide evidence for a contribution of CD30 (TNFRSF8) and its ligand CD30L (TNFSF8) expressed on NK cells and DCs, respectively. We demonstrate that CD30-mediated engagement of CD30L induced cytokine secretion from immature DCs via the mitogen-activated protein kinase pathway. Moreover, CD30L engagement promoted differentiation to mature DCs. On the contrary, the engagement of CD30 on NK cells resulted in an NF-κB-dependent release of TNF-α/IFN-γ. These data uncover a novel and unexpected role for CD30/CD30L that contributes to proinflammatory immune responses.
[Show abstract][Hide abstract] ABSTRACT: Cancer that might develop as host natural killer (NK) cells fail to detect ligands for their activating NK receptors. Immunoligands represent promising immunotherapeutic tools to overcome this deficit. These are fusion proteins containing a single-chain antibody fragment (scFv) to target an available tumor antigen and ULBP2 to activate host NK cells by targeting the activatory receptor NKG2D. Prostate-specific membrane antigen (PSMA) is an integral non-shed type 2 membrane protein that is highly and specifically expressed on prostate epithelial cells and strongly upregulated in prostate cancer. Here, we compare the impact of various anti-PSMA immunoligand formats on the therapeutic efficacy against prostate carcinoma cells by activating NK cells via NKG2D. Shortening of the linker separating the heavy and light chain antibody domain leads to the formation of dimers, trimers, and higher molecular mass oligomers. NK cells are most efficiently activated by multimeric immunoligands, thus showing an altered cytokine release pattern. The high avidity format is also superior in in vitro NK-mediated tumor cell targeting as shown in cytotoxicity assays. Finally, the efficacy of a multimeric immunoligand is shown in a prostate carcinoma mouse xenograft model showing a strong activity against advanced established tumors.
Molecular Cancer Therapeutics 06/2011; 10(6):1036-45. · 5.60 Impact Factor