Decitabine has a biphasic effect on natural killer cell viability, phenotype, and function under proliferative conditions

Effect of decitabine on PD-L2 methylation in whole blood of iodine-induced autoimmune thyroiditis rats

Excessive iodine intake can induce autoimmune thyroiditis (AIT), and the methylation of programmed death receptor 2 (PD-L2) may be involved in the development of iodine-induced AIT. Here, we investigated the immune role of methylation of the susceptibility gene PD-L2 in the occurrence of iodine-induced AIT using the DNA methyltransferase inhibitor Decitabine (Dec) in an experimental autoimmune thyroiditis (EAT) rat model. After injecting Dec intraperitoneally into EAT rats, we performed arsenic-cerium catalytic spectrophotometry, pathological hematoxylin and eosin staining, enzyme-linked immunosorbent assay, quantitative methylation-specific polymerase chain reaction (qMSP), and quantitative real-time polymerase chain reaction (qPCR) to determine the relevant indices. The results showed that compared with the control group, the urinary iodine, thyroid lymphocyte infiltration, thyroglobulin antibody (TgAb), interferon (IFN-γ), and interleukin (IL-23) levels of the EAT rats were significantly increased. The PD-L2 methylation levels were significantly decreased in EAT rats compared to control rats, and the mRNA expression of the PD-L2 was significantly increased. Following Dec intervention, the methylation level of the PD-L2 in rats increased and interferon and interleukin-23 levels decreased, albeit not significantly. However, the mRNA expression of PD-L2 decreased significantly after Dec intervention, and the thyroid function of EAT rats also showed a gradual improvement trend. In summary, hypomethylation of PD-L2 is closely related to the development of iodine-induced AIT. Pro-inflammatory cellular factors are also involved in iodine-induced AIT progression. Although Dec shows promise in the treatment of AIT, further evaluation of its safety is necessary.

Effects of epigenetic therapy on natural killer cell function and development in hematologic malignancy

Epigenetic therapy is an emerging field in the treatment of human cancer, including hematologic malignancies. This class of therapeutic agents approved by the US Food and Drug Administration for cancer treatment includes DNA hypomethylating agents, histone deacetylase inhibitors, IDH1/2 inhibitors, EZH2 inhibitors, and numerous preclinical targets/agents. Most studies measuring the biological effects of epigenetic therapy focus their attention on either their direct cytotoxic effects on malignant cells or their effects on modifying tumor cell antigen expression, exposing them to immune surveillance mechanisms. However, a growing body of evidence suggests that epigenetic therapy also has effects on the development and function of the immune system, including natural killer cells, which can alter their response to cancer cells. In this review, we summarize the body of literature studying the effects of different classes of epigenetic therapy on the development and/or function of natural killer cells.

Epigenetic modulation and prostate cancer: Paving the way for NK cell anti-tumor immunity

Immunoepigenetics is a growing field, as there is mounting evidence on the key role played by epigenetic mechanisms in the regulation of tumor immune cell recognition and control of immune cell anti-tumor responses. Moreover, it is increasingly acknowledgeable a tie between epigenetic regulation and prostate cancer (PCa) development and progression. PCa is intrinsically a cold tumor, with scarce immune cell infiltration and low inflammatory tumor microenvironment. However, Natural Killer (NK) cells, main anti-tumor effector immune cells, have been frequently linked to improved PCa prognosis. The role that epigenetic-related mechanisms might have in regulating both NK cell recognition of PCa tumor cells and NK cell functions in PCa is still mainly unknown. Epigenetic modulating drugs have been showing boundless therapeutic potential as anti-tumor agents, however their role in immune cell regulation and recognition is scarce. In this review, we focused on studies addressing modulation of epigenetic mechanisms involved in NK cell-mediated responses, including both the epigenetic modulation of tumor cell NK ligand expression and NK cell receptor expression and function in different tumor models, highlighting studies in PCa. The integrated knowledge from diverse epigenetic modulation mechanisms promoting NK cell-mediated immunity in various tumor models might open doors for the development of novel epigenetic-based therapeutic options for PCa management.

Immune Profile of Blood, Tissue and Peritoneal Fluid: A Comparative Study in High Grade Serous Epithelial Ovarian Cancer Patients at Interval Debulking Surgery

High-grade serous epithelial ovarian carcinoma (HGSOC) is an immunogenic tumor with a unique tumor microenvironment (TME) that extends to the peritoneal cavity. The immunosuppressive nature of TME imposes the major challenge to develop effective treatment options for HGSOC. Interaction of immune cells in TME is an important factor. Hence, a better understanding of immune profile of TME may be required for exploring alternative treatment options. Immune profiling of peritoneal fluid (PF), tumor specimens, and blood were carried out using flowcytometry, ELISA, and Procartaplex immunoassay. The frequency of CD56^BrightNK cells and expression of functional receptors were reduced in PF. Increased activating NKp46+CD56^DimNK cells may indicate differential antitumor response in PF. Functional receptors on NK, NKT-like and T cells were reduced more drastically in tumor specimens. Soluble ligands MIC-B and PVR were reduced, whereas B7-H6 was increased in PF. Dissemination of tumor cells contributes to soluble ligands in PF. A differential cytokine profile was found in serum and PF as IL-2, IL-8, IL-15, IL-27, IFN-γ, and GM-CSF were elevated specifically in PF. In conclusion, the differential immune profile and correlation of soluble parameters and NK cell receptors with chemo response score may add knowledge to understand anti-tumor immune response to develop effective treatment modality.

Understanding the Crosstalk Between Epigenetics and Immunometabolism to Combat Cancer

The interaction between metabolic and epigenetic events shapes metabolic adaptations of cancer cells and also helps rewire the proliferation and activity of surrounding immune cells in the tumor microenvironment (TME). Recent studies indicate that the TME imposes metabolic constraints on immune cells, inducing them to attain a tolerogenic state, incompetent of mounting effective tumor eradication. Owing to extensive mutations acquired over repeated cell divisions, tumor cells selectively accumulate metabolites that regulate the activity of key epigenetic enzymes to mediate activation/suppression of genes associated with T-cell function and macrophage polarization. Further, multiple modulators connecting epigenetic and metabolic pathways help dictate the preferential induction of cytokines and expression of lineage-specifying genes associated with immunosuppressive T-cell differentiation.In this chapter, we attempt to discuss the mechanisms underpinning the metabolic and epigenetic interplay in immune cells of the TME and how modulating these events can boost the application of existing anticancer immunotherapy.

Epigenetic regulation of natural killer cell memory

Immunological memory is the underlying mechanism by which the immune system remembers previous encounters with pathogens to produce an enhanced secondary response upon re-encounter. It stands as the hallmark feature of the adaptive immune system and the cornerstone of vaccine development. Classic recall responses are executed by conventional T and B cells, which undergo somatic recombination and modify their receptor repertoire to ensure recognition of a vast number of antigens. However, recent evidence has challenged the dogma that memory responses are restricted to the adaptive immune system, which has prompted a reevaluation of what delineates "immune memory." Natural killer (NK) cells of the innate immune system have been at the forefront of these pushed boundaries, and have proved to be more "adaptable" than previously thought. Like T cells, we now appreciate that their "natural" abilities actually require a myriad of signals for optimal responses. In this review, we discuss the many signals required for effector and memory NK cell responses and the epigenetic mechanisms that ultimately endow their enhanced features.

Concentration-Dependent Decitabine Effects on Primary NK Cells Viability, Phenotype, and Function in the Absence of Obvious NK Cells Proliferation-Original Article

Acute myeloid leukemia (AML) cells can evade innate immune killing by modulating natural killer (NK) cells receptors and their cognate ligands in tumor cells, thus it may be possible to restore proper expression of immune receptors or ligands with immune sensitive drugs. Decitabine, as a hypomethylation agent, was approved for the treatment of AML and myelodysplastic syndrome. While clinical responses were contributed by epigenetic effects and the induction of cancer cell apoptosis, decitabine also has immune-mediated anti-tumor effects. After exposure to various concentration of decitabine for 24 h, the primary NK cells (AML-NK cells) cytotoxicity and receptor expression (NKG2D and NKp46) displayed parabola-shaped response, while U-shaped response was seen in cytokine release (IFN-γ and IL-10), and these effects were regulated by ERK and STAT3 phosphorylation level. Furthermore, AML-NK cells function displayed different response when the competitive MEK and STAT3 inhibitors applied respectively. Thus, we could conclude that the different dose of decitabine makes various effects on AML-NK cells function and receptors expression.

Association Analyses of TP53 Mutation With Prognosis, Tumor Mutational Burden, and Immunological Features in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease related to a broad spectrum of molecular alterations. The successes of immunotherapies treating solid tumors and a deeper understanding of the immune systems of patients with hematologic malignancies have promoted the development of immunotherapies for the treatment of AML. And high tumor mutational burden (TMB) is an emerging predictive biomarker for response to immunotherapy. However, the association of gene mutation in AML with TMB and immunological features still has not been clearly elucidated. In our study, based on The Cancer Genome Atlas (TCGA) and BeatAML cohorts, 20 frequently mutated genes were found to be covered by both datasets in AML. And TP53 mutation was associated with a poor prognosis, and its mutation displayed exclusiveness with other common mutated genes in both datasets. Moreover, TP53 mutation correlated with TMB and the immune microenvironment. Gene Set Enrichment Analysis (GSEA) showed that TP53 mutation upregulated signaling pathways involved in the immune system. In summary, TP53 mutation is frequently mutated in AML, and its mutation is associated with dismal outcome, TMB, and immunological features, which may serve as a biomarker to predict immune response in AML.

Can the New and Old Drugs Exert an Immunomodulatory Effect in Acute Myeloid Leukemia?

Simple Summary

The advent of novel immunotherapeutic strategies has revealed the importance of immune dysregulation and of a tolerogenic microenvironment for acute myeloid leukemia (AML) fitness. We reviewed the “off-target” effects on the immune system of different drugs used in the treatment of AML to explore the advantages of this unexpected interaction.

Abstract

Acute myeloid leukemia (AML) is considered an immune-suppressive neoplasm capable of evading immune surveillance through cellular and environmental players. Increasing knowledge of the immune system (IS) status at diagnosis seems to suggest ever more attention of the crosstalk between the leukemic clone and its immunologic counterpart. During the last years, the advent of novel immunotherapeutic strategies has revealed the importance of immune dysregulation and suppression for leukemia fitness. Considering all these premises, we reviewed the “off-target” effects on the IS of different drugs used in the treatment of AML, focusing on the main advantages of this interaction. The data reported support the idea that a successful therapeutic strategy should consider tailored approaches for performing leukemia eradication by both direct blasts killing and the engagement of the IS.

Inflammatory and Immune Disorders Associated with Myelodysplastic Syndromes

Systemic auto-inflammatory or autoimmune diseases (SIADs) develop in up to a quarter of patients with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML). With or without the occurrence of SIADs, the distribution of MDS subtypes and the international or CMML-specific prognostic scoring systems have been similar between MDS/CMML patients. Moreover, various SIADs have been described in association with MDS, ranging from limited clinical manifestations to systemic diseases affecting multiple organs. Defined clinical entities including systemic vasculitis, connective tissue diseases, inflammatory arthritis and neutrophilic diseases are frequently reported; however, unclassified or isolated organ impairment can also be seen. Although the presence of SIADs does not impact the overall survival nor disease progression to acute myeloid leukemia, they can help with avoiding steroid dependence and make associated adverse events of immunosuppressive drugs challenging. While therapies using steroids and immunosuppressive treatment remain the backbone of first-line treatment, increasing evidence suggests that MDS specific therapy (hypomethylating agents) and sparing steroids may be effective in treating such complications based on their immunomodulatory effect. The aim of this review was to analyze the epidemiological, pathophysiological, clinical and therapeutic factors of systemic inflammatory and immune disorders associated with MDS.

Epigenetic Regulation of NK Cell-Mediated Antitumor Immunity

Natural killer (NK) cells are critical innate lymphocytes that can directly kill target cells without prior immunization. NK cell activation is controlled by the balance of multiple germline-encoded activating and inhibitory receptors. NK cells are a heterogeneous and plastic population displaying a broad spectrum of functional states (resting, activating, memory, repressed, and exhausted). In this review, we present an overview of the epigenetic regulation of NK cell-mediated antitumor immunity, including DNA methylation, histone modification, transcription factor changes, and microRNA expression. NK cell-based immunotherapy has been recognized as a promising strategy to treat cancer. Since epigenetic alterations are reversible and druggable, these studies will help identify new ways to enhance NK cell-mediated antitumor cytotoxicity by targeting intrinsic epigenetic regulators alone or in combination with other strategies.

Hypomethylating Agents and Immunotherapy: Therapeutic Synergism in Acute Myeloid Leukemia and Myelodysplastic Syndromes

Decitabine and guadecitabine are hypomethylating agents (HMAs) that exert inhibitory effects against cancer cells. This includes stimulation of anti-tumor immunity in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) patients. Treatment of AML and MDS patients with the HMAs confers upregulation of cancer/testis antigens (CTAs) expression including the highly immunogenic CTA NY-ESO-1. This leads to activation of CD4⁺ and CD8⁺ T cells for elimination of cancer cells, and it establishes the feasibility to combine cancer vaccine with HMAs to enhance vaccine immunogenicity. Moreover, decitabine and guadecitabine induce the expression of immune checkpoint molecules in AML cells. In this review, the accumulating knowledge on the immunopotentiating properties of decitabine and guadecitabine in AML and MDS patients are presented and discussed. In summary, combination of decitabine or guadecitabine with NY-ESO-1 vaccine enhances vaccine immunogenicity in AML patients. T cells from AML patients stimulated with dendritic cell (DC)/AML fusion vaccine and guadecitabine display increased capacity to lyse AML cells. Moreover, decitabine enhances NK cell-mediated cytotoxicity or CD123-specific chimeric antigen receptor-engineered T cells antileukemic activities against AML. Furthermore, combination of either HMAs with immune checkpoint blockade (ICB) therapy may circumvent their resistance. Finally, clinical trials of either HMAs combined with cancer vaccines, NK cell infusion or ICB therapy in relapsed/refractory AML and high-risk MDS patients are currently underway, highlighting the promising efficacy of HMAs and immunotherapy synergy against these malignancies.

Prospects for NK Cell Therapy of Sarcoma

Simple Summary

Sarcomas are a group of aggressive tumors originating from mesenchymal tissues. Patients with advanced disease have poor prognosis due to the ineffectiveness of current treatment protocols. A subset of lymphocytes called natural killer (NK) cells is capable of effective surveillance and clearance of sarcomas, constituting a promising tool for immunotherapeutic treatment. However, sarcomas can cause impairment in NK cell function, associated with enhanced tumor growth and dissemination. In this review, we discuss the molecular mechanisms of sarcoma-mediated suppression of NK cells and their implications for the design of novel NK cell-based immunotherapies against sarcoma.

Abstract

Natural killer (NK) cells are innate lymphoid cells with potent antitumor activity. One of the most NK cell cytotoxicity-sensitive tumor types is sarcoma, an aggressive mesenchyme-derived neoplasm. While a combination of radical surgery and radio- and chemotherapy can successfully control local disease, patients with advanced sarcomas remain refractory to current treatment regimens, calling for novel therapeutic strategies. There is accumulating evidence for NK cell-mediated immunosurveillance of sarcoma cells during all stages of the disease, highlighting the potential of using NK cells as a therapeutic tool. However, sarcomas display multiple immunoevasion mechanisms that can suppress NK cell function leading to an uncontrolled tumor outgrowth. Here, we review the current evidence for NK cells’ role in immune surveillance of sarcoma during disease initiation, promotion, progression, and metastasis, as well as the molecular mechanisms behind sarcoma-mediated NK cell suppression. Further, we apply this basic understanding of NK–sarcoma crosstalk in order to identify and summarize the most promising candidates for NK cell-based sarcoma immunotherapy.

KMT2A/C mutations function as a potential predictive biomarker for immunotherapy in solid tumors

Epigenetic factors play important roles in tumor immunology. Histone-lysine N-methyltransferase 2 (KMT2) family genes exert histone H3 methylation, but its role in immunotherapy remains unclear. Our study is the first to investigate the correlation between KMT2 gene mutations and the clinical benefit of immune checkpoint inhibitors (ICI) treatment. We firstly collected a primary ICI-treated cohort (n = 546) and found that patients with KMT2A/C mutations yielded better prognosis in terms of progression-free survival (PFS, Hazard ratio [HR] = 0.66, P = 0.002), objective response rate (ORR, 40.9% vs 20.3%, P < 0.001), durable clinical benefit (DCB, 48.3% vs 29.8%, P = 0.001) and overall survival (OS, HR = 0.70, P = 0.033). Furthermore, we validated the predictive potential of KMT2A/C mutations in an expanded ICI-treated cohort (n = 1395). KMT2A/C-mutant patients achieved better OS compared with KMT2A/C-wildtype patients (HR = 0.68, P = 0.003); and the survival advantages appeared in the majority of cancer subtypes. Our study suggests that KMT2A/C mutations function as a novel and potential predictive biomarker for ICI treatment in multiple solid tumors and the underlying mechanism is worth investigating.

Natural Killer Cell Immunotherapy for Osteosarcoma

Natural killer (NK) cells are lymphocytes of the innate immune system that have the ability to recognize malignant cells through balanced recognition of cell-surface indicators of stress and danger. Once activated through such recognition, NK cells release cytokines and induce target cell lysis through multiple mechanisms. NK cells are increasingly recognized for their role in controlling tumor progression and metastasis and as important mediators of immunotherapeutic modalities such as cytokines, antibodies, immunomodulating drugs, and stem cell transplantation. Recent advances in manipulating NK cell number, function, and genetic modification have caused renewed interest in their potential for adoptive immunotherapies, which are actively being tested in clinical trials. Here, we summarize the evidence for NK cell recognition of osteosarcoma, discuss immune therapies that are directly or indirectly dependent on NK cell function, and describe potential approaches for manipulating NK cell number and function to enhance therapy against osteosarcoma.

Changes in IDH2, TET2 and KDM2B Gene Expression After Treatment With Classic Chemotherapeutic Agents and Decitabine in Myelogenous Leukemia Cell Lines

Background

Hematological malignancies are a heterogeneous group of tumors with increased proliferative and auto-replicative capacity. Despite treatment advances, post-treatment quality of life remains highly affected. Studies addressing the molecular mechanisms of these diseases are critical for the development of effective, rapid and selective therapies, since few therapeutic strategies succeed in being effective without triggering high-grade toxicities or debilitating late effects. Our aim of this study was to verify changes in the expression of genes involved in the malignant phenotype of hematological malignancies, by treating human cell lines in vitro with classic chemotherapeutic agents and the demethylating agent, decitabine.

Methods

KASUMI-1 and K-562 human myeloid leukemia cell lines were plated at a density of 3 × 10⁴ cells/well and treated with increasing concentrations of different chemotherapeutic agents commonly used in the clinical setting. After 24 and 48 h of treatment, cell viability was tested, and RNA was extracted. Complementary DNA (cDNA) was synthesized and quantitative real-time polymerase chain reaction (qPCR) was performed to evaluate the gene expression of IDH2, TET2 and KDM2B.

Results

A modulation in gene expression was observed before and after treatment with classic chemotherapeutic agents. It was possible to demonstrate a difference in gene expression when cells were treated with chemotherapeutic agents or decitabine alone when compared to chemotherapeutic agents in association with decitabine.

Conclusions

The genes tested, and the modulation of their expression during in vitro treatments suggest that IDH2, TET2, and KDM2B should be further investigated as potential biomarkers for ongoing treatment response and follow-up for patients diagnosed with hematological malignancies of the myeloid lineage.

Epigenomics-Guided Drug Development: Recent Advances in Solving the Cancer Treatment "jigsaw puzzle"

The human epigenome plays a key role in determining cellular identity and eventually function. Drug discovery undertakings have focused mainly on the role of genomics in carcinogenesis, with the focus turning to the epigenome recently. Drugs targeting DNA and histone modifications are under development with some such as 5-azacytidine, decitabine, vorinostat, and panobinostat already approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This expert review offers a critical analysis of the epigenomics-guided drug discovery and development and the opportunities and challenges for the next decade. Importantly, the coupling of epigenetic editing techniques, such as clustered regularly interspersed short palindromic repeat (CRISPR)-CRISPR-associated protein-9 (Cas9) and APOBEC-coupled epigenetic sequencing (ACE-seq) with epigenetic drug screens, will allow the identification of small-molecule inhibitors or drugs able to reverse epigenetic changes responsible for many diseases. In addition, concrete and sustainable innovation in cancer treatment ought to integrate epigenome targeting drugs with classic therapies such as chemotherapy and immunotherapy.

DNA Methyltransferase Inhibitors: Catalysts For Antitumour Immune Responses

Epigenetics is a kind of heritable change that involves the unaltered DNA sequence and can have effects on gene expression. The regulatory mechanism mainly includes DNA methylation, histone modification and non-coding RNA regulation. DNA methylation is currently the most studied aspect of epigenetics. It is widely present in eukaryotic cells and is the most important epigenetic mark in the regulation of gene expression in the cell. DNA methyltransferase inhibitors (DNMTi) have been increasingly recognized in the field of cancer immunotherapy, have been approved for the treatment of acute myeloid leukaemia (AML) and are widely being used in clinical trials of cancer immunotherapies. DNMTi promote the reactivation of tumour suppressor genes, enhance tumour immunogenicity, and stimulate a variety of immune cells to secrete cytokines that exert cytotoxic effects, promote tumour cell death, including macrophages, natural killer (NK) cells and CD8+ T cells, and upregulate major histocompatibility complex (MHC) class I expression levels. Here, we mainly summarize the epigenetics related to DNMTi and their regulation of the antitumour immune response and DNMTi combined with immuno-therapeutics or histone deacetylase inhibitors to demonstrate the great development potential and clinical application value of DNMTi.

Survival of early posthematopoietic stem cell transplantation relapse of myeloid malignancies

Objective

Relapse of AML after allogeneic hematopoietic stem cell transplantation (HSCT) has a poor prognosis, and standard of care therapy is lacking. Early (<6 months) relapse is associated with dismal outcome, while the majority of relapses occur early after transplantation. A more precise indication which patients could benefit from reinduction therapy is warranted.

Methods

We retrospectively analyzed outcomes of 83 patients with postallogeneic HSCT relapse. Patients were divided based on intention to treat (curative vs supportive care).

Results

Of the 50 patients treated with curative intent, 44% reached complete remission (CR) upon reinduction chemotherapy, and of these patients, 50% survived. Two survivors reached CR after immunotherapy (donor lymphocyte infusion (DLI), without reinduction chemotherapy). Sixty‐nine percent of the survivors had received high‐intensity cytarabine treatment, followed by immunologic consolidation. Relapse <3 months after transplantation was predictive for adverse survival (P = .004), but relapse <6 months was not. In fact, >50% of the survivors had a relapse <6 months.

Conclusion

We confirmed the dismal prognosis of postallogeneic HSCT relapse. Importantly, our data demonstrate that patients fit enough to receive high‐dose chemotherapy, even when relapse occurred <6 months, had the best chance to obtain durable remissions, in particular when immunologic consolidation was performed after reaching CR.

ILCs in hematologic malignancies: Tumor cell killers and tissue healers

Innate lymphoid cells (ILCs) have attracted considerable attention in the past years. As modulators of epithelial barrier immunology and homeostasis they play important roles in (auto)immunity and inflammation. Here we review the role of ILCs in hematologic malignancies, where ILCs act as efficient killer cells and as tissue healers, in the context of chemotherapy, radiotherapy and after allogeneic hematopoietic stem cell transplantation (HSCT).

Phase I clinical trial of decitabine (5-aza-2'-deoxycytidine) administered by hepatic arterial infusion in patients with unresectable liver-predominant metastases

DNA demethylating agents may increase the immunogenicity of malignant tumours and increase the efficacy of subsequent treatment with immune check point inhibitors. We investigated the safety of administrating the demethylating agent decitabine by hepatic arterial infusionin patients with unresectable liver meta stases from solid tumours in a dose escalation phase I clinical trial. A total of nine eligible patients were enrolled and initiated study treatment at three different dose levels (two patients at 10, four at 15 and six at a dose level of 20mg decitabine/m2/day) (per protocol there was no intent to escalate the dose above the median tolerated intravenous dose level). Decitabine was administered as a 1-hour hepatic arterial infusion on five consecutive days every 4 weeks. Intrapatient dose escalation was applied in five patients. Grades 1 and 2 haematological toxicity was the most frequent treatment-related adverse event. None of the patients experienced treatment-limiting adverse events. Expression analysis of 30 cancer test is antigens (CTA) in pretreatment and post-treatment biopsies from patients indicated an increased expression of 21 CTAs after treatment. There were no objective tumour responses on study treatment or during post study exposure to immune checkpoint therapy in four patients with uveal melanoma liver metastases. We conclude that the investigate d hepatic arterial administration regimen for decitabine can be safely applied, and a dose level of 20 mg/m2/day on five consecutive days every 4 weeks can be considered for further investigation in combinatorial immunotherapy regimens.

Efficacy of azacitidine is independent of molecular and clinical characteristics - an analysis of 128 patients with myelodysplastic syndromes or acute myeloid leukemia and a review of the literature

Azacitidine is the first drug to demonstrate a survival benefit for patients with MDS. However, only half of patients respond and almost all patients eventually relapse. Limited and conflicting data are available on predictive factors influencing response. We analyzed 128 patients from two institutions with MDS or AML treated with azacitidine to identify prognostic indicators. Genetic mutations in ASXL1, RUNX1, DNMT3A, IDH1, IDH2, TET2, TP53, NRAS, KRAS, FLT3, KMT2A-PTD, EZH2, SF3B1, and SRSF2 were assessed by next-generation sequencing. With a median follow up of 5.6 years median survival was 1.3 years with a response rate of 49%. The only variable with significant influence on response was del(20q). All 6 patients responded (p = 0.012) but survival was not improved. No other clinical, cytogenetic or molecular marker for response or survival was identified. Interestingly, patients from poor-risk groups as high-risk cytogenetics (55%), t-MDS/AML (54%), TP53 mutated (48%) or relapsed after chemotherapy (60%) showed a high response rate. Factors associated with shorter survival were low platelets, AML vs. MDS, therapy-related disease, TP53 and KMT2A-PTD. In multivariate analysis anemia, platelets, FLT3-ITD, and therapy-related disease remained in the model. Poor-risk factors such as del(7q)/-7, complex karyotype, ASXL1, RUNX1, EZH2, and TP53 did not show an independent impact. Thus, no clear biomarker for response and survival can be identified. Although a number of publications on predictive markers for response to AZA exist, results are inconsistent and improved response rates did not translate to improved survival. Here, we provide a comprehensive overview comparing the studies published to date.

Decitabine Inhibits Gamma Delta T Cell Cytotoxicity by Promoting KIR2DL2/3 Expression

Gamma delta (γδ) T cells, which possess potent cytotoxicity against a wide range of cancer cells, have become a potential avenue for adoptive immunotherapy. Decitabine (DAC) has been reported to enhance the immunogenicity of tumor cells, thereby reinstating endogenous immune recognition and tumor lysis. However, DAC has also been demonstrated to have direct effects on immune cells. In this study, we report that DAC inhibits γδ T cell proliferation. In addition, DAC increases the number of KIR2DL2/3-positive γδ T cells, which are less cytotoxic than the KIR2DL2/3-negative γδ T cells. We found that DAC upregulated KIR2DL2/3 expression in KIR2DL2/3-negative γδ T cells by inhibiting KIR2DL2/3 promoter methylation, which enhances the binding of KIR2DL2/3 promoter to Sp-1 and activates KIR2DL2/3 gene expression. Our data demonstrated that DAC can inhibit the function of human γδ T cells at both cellular and molecular levels, which confirms and extrapolates the results of previous studies showing that DAC can negatively regulate the function of NK cells and αβ T cells of the immune system.

Decitabine enhances targeting of AML cells by CD34+ progenitor-derived NK cells in NOD/SCID/IL2Rgnull mice

Combining natural killer (NK) cell adoptive transfer with hypomethylating agents (HMAs) is an attractive therapeutic approach for patients with acute myeloid leukemia (AML). However, data regarding the impact of HMAs on NK cell functionality are mostly derived from in vitro studies with high nonclinical relevant drug concentrations. In the present study, we report a comparative study of azacitidine (AZA) and decitabine (DAC) in combination with allogeneic NK cells generated from CD34⁺ hematopoietic stem and progenitor cells (HSPC-NK cells) in in vitro and in vivo AML models. In vitro, low-dose HMAs did not impair viability of HSPC-NK cells. Furthermore, low-dose DAC preserved HSPC-NK killing, proliferation, and interferon gamma production capacity, whereas AZA diminished their proliferation and reactivity. Importantly, we showed HMAs and HSPC-NK cells could potently work together to target AML cell lines and patient AML blasts. In vivo, both agents exerted a significant delay in AML progression in NOD/SCID/IL2Rg^null mice, but the persistence of adoptively transferred HSPC-NK cells was not affected. Infused NK cells showed sustained expression of most activating receptors, upregulated NKp44 expression, and remarkable killer cell immunoglobulin-like receptor acquisition. Most importantly, only DAC potentiated HSPC-NK cell anti-leukemic activity in vivo. Besides upregulation of NKG2D- and DNAM-1-activating ligands on AML cells, DAC enhanced messenger RNA expression of inflammatory cytokines, perforin, and TRAIL by HSPC-NK cells. In addition, treatment resulted in increased numbers of HSPC-NK cells in the bone marrow compartment, suggesting that DAC could positively modulate NK cell activity, trafficking, and tumor targeting. These data provide a rationale to explore combination therapy of adoptive HSPC-NK cells and DAC in patients with AML.

Boosting Natural Killer Cell-Based Immunotherapy with Anticancer Drugs: a Perspective

Natural killer (NK) cells efficiently recognize and kill tumor cells through several mechanisms including the expression of ligands for NK cell-activating receptors on target cells. Different clinical trials indicate that NK cell-based immunotherapy represents a promising antitumor treatment. However, tumors develop immune-evasion strategies, including downregulation of ligands for NK cell-activating receptors, that can negatively affect antitumor activity of NK cells, which either reside endogenously, or are adoptively transferred. Thus, restoration of the expression of NK cell-activating ligands on tumor cells represents a strategic therapeutic goal. As discussed here, various anticancer drugs can fulfill this task via different mechanisms. We envision that the combination of selected chemotherapeutic agents with NK cell adoptive transfer may represent a novel strategy for cancer immunotherapy.

Immunological effects of hypomethylating agents

INTRODUCTION

Epigenetic changes resulting from aberrant methylation patterns are a recurrent observation in hematologic malignancies. Hypomethylating agents have a well-established role in the management of patients with high-risk myelodysplastic syndrome or acute myeloid leukemia. In addition to the direct effects of hypomethylating agents on cancer cells, there are several lines of evidence indicating a role for immune-mediated anti-tumor benefits from hypomethylating therapy. Areas covered: We reviewed the clinical and basic science literature for the effects of hypomethylating agents, including the most commonly utilized therapeutics azacitidine and decitabine, on immune cell subsets. We summarized the effects of hypomethylating agents on the frequency and function of natural killer cells, T cells, and dendritic cells. In particular, we highlight the effects of hypomethylating agents on expression of immune checkpoint inhibitors, leukemia-associated antigens, and endogenous retroviral elements. Expert commentary: In vitro and ex vivo studies indicate mixed effects on the function of natural killer, dendritic cells and T cells following treatment with hypomethylating agents. Clinical correlates of immune function have suggested that hypomethylating agents have immunomodulatory functions with the potential to synergize with immune checkpoint therapy for the treatment of hematologic malignancy, and has become an active area of clinical research.

Drug discovery and therapeutic delivery for the treatment of B and T cell tumors

Hematological malignancies manifest as lymphoma, leukemia, and myeloma, and remain a burden on society. From initial therapy to endless relapse-related treatment, societal burden is felt not only in the context of healthcare cost, but also in the compromised quality of life of patients. Long-term therapeutic strategies have become the standard in keeping hematological malignancies at bay as these cancers develop resistance to each round of therapy with time. As a result, there is a continual need for the development of new drugs to combat resistant disease in order to prolong patient life, if not to produce a cure. This review aims to summarize advances in targeting lymphoma, leukemia, and myeloma through both cutting-edge and well established platforms. Current standard of treatment will be reviewed for these malignancies and emphasis will be made on new therapy development in the areas of antibody engineering, epigenetic small molecule inhibiting drugs, vaccine development, and chimeric antigen receptor cell engineering. In addition, platforms for the delivery of these and other drugs will be reviewed including antibody-drug conjugates, micro- and nanoparticles, and multimodal hydrogels. Lastly, we propose that tissue engineered constructs for hematological malignancies are the missing link in targeted drug discovery alongside mouse and patient-derived xenograft models.

Primary adrenal insufficiency is associated with impaired natural killer cell function: a potential link to increased mortality

OBJECTIVE

Mortality in patients with primary adrenal insufficiency (PAI) is significantly increased, with respiratory infections as a major cause of death. Moreover, patients with PAI report an increased rate of non-fatal infections. Neutrophils and natural killer (NK) cells are innate immune cells that provide frontline protection against invading pathogens. Thus, we compared the function and phenotype of NK cells and neutrophils isolated from PAI patients and healthy controls to ascertain whether altered innate immune responses could be a contributory factor for the increased susceptibility of PAI patients to infection.

DESIGN AND METHODS

We undertook a cross-sectional study of 42 patients with PAI due to autoimmune adrenalitis (n = 37) or bilateral adrenalectomy (n = 5) and 58 sex- and age-matched controls. A comprehensive screen of innate immune function, consisting of measurements of neutrophil phagocytosis, reactive oxygen species production, NK cell cytotoxicity (NKCC) and NK cell surface receptor expression, was performed on all subjects.

RESULTS

Neutrophil function did not differ between PAI and controls. However, NKCC was significantly reduced in PAI (12.0 ± 1.5% vs 21.1 ± 2.6%, P < 0.0001). Phenotypically, the percentage of NK cells expressing the activating receptors NKG2D and NKp46 was significantly lower in PAI, as was the surface density of NKG2D (all P < 0.0001). Intracellular granzyme B expression was significantly increased in NK cells from PAI patients (P < 0.01).

CONCLUSIONS

Adrenal insufficiency is associated with significantly decreased NKCC, thereby potentially compromising early recognition and elimination of virally infected cells. This potential impairment in anti-viral immune defense may contribute to the increased rate of respiratory infections and ultimately mortality in PAI.

Marked for death: targeting epigenetic changes in cancer

In the past few years, it has become clear that mutations in epigenetic regulatory genes are common in human cancers. Therapeutic strategies are now being developed to target cancers with mutations in these genes using specific chemical inhibitors. In addition, a complementary approach based on the concept of synthetic lethality, which allows exploitation of loss-of-function mutations in cancers that are not targetable by conventional methods, has gained traction. Both of these approaches are now being tested in several clinical trials. In this Review, we present recent advances in epigenetic drug discovery and development, and suggest possible future avenues of investigation to drive progress in this area.

Cancer treatment and the KIR-HLA system: an overview

Accumulating evidence indicates that the success of cancer therapy depends not only on a combination of adequate procedures (surgery, chemotherapy and radiotherapy) that aim to eliminate all tumor cells, but also on the functional state of the host immune system. HLA and KIR molecules, in particular, are critical to the interactions between tumor cells and both innate and adaptive immune cells such as NK cells and T cells. Different KIR-HLA gene combinations as well as different HLA expression levels on tumor cells associate with variable tumor prognosis and response to treatment. On the other hand, different therapies have different effects on HLA molecules and immune cell functions regulated by these molecules. Here, we provide an overview of the KIR-HLA system, a description of its alterations with clinical relevance in diverse tumor types, and an analysis of the consequences that conventional cancer therapies may have on it. We also discuss how this knowledge can be exploited to identify potential immunological biomarkers that can help to select patients for tailored therapy.

Emerging role of immunotherapy in urothelial carcinoma-Future directions and novel therapies

Tremendous advances in our understanding of the tumor immunology and molecular biology of urothelial carcinoma (UC) have led to the recent approval of immunotherapy as a novel option for patients with UC with advanced disease. Despite the promising data of novel immune checkpoint inhibitors, only a small subset of patients with UC achieves durable remissions. Because an optimal antitumor response requires coordination of multiple immune, tumor, and microenvironment effector cells, novel approaches targeting distinct mechanisms of action likely in combination are needed. In addition, discovery of reliable immune biomarkers, understanding of mechanisms of resistance, and novel clinical trial designs are warranted for maximum benefit of UC immunotherapy.

Combination treatment with decitabine and ionizing radiation enhances tumor cells susceptibility of T cells

Decitabine has been found to have anti-metabolic and anti-tumor activities in various tumor cells. Recently, the use of decitabine in combination with other conventional therapies reportedly resulted in improved anti-tumor activity against various tumors. Ionizing radiation (IR) is widely used as a cancer treatment. Decitabine and IR improve immunogenicity and susceptibility of tumor cells to immune cells by up-regulating the expression of various molecules such as major histocompatibility complex (MHC) class I; natural-killer group 2, member D (NKG2D) ligands; and co-stimulatory molecules. However, the effects of combining decitabine and IR therapies are largely unknown. Our results indicate that decitabine or IR treatment upregulates MHC class I, along with various co-stimulatory molecules in target tumor cells. Furthermore, decitabine and IR combination treatment further upregulates MHC class I, along with the co-stimulatory molecules, when compared to the effect of each treatment alone. Importantly, decitabine treatment further enhanced T cell-mediated cytotoxicity and release of IFN- γ against target tumor cells which is induced by IR. Interestingly, decitabine did not affect NKG2D ligand expression or NK cell-mediated cytotoxicity in target tumor cells. These observations suggest that decitabine may be used as a useful immunomodulator to sensitize tumor cells in combination with other tumor therapies.

Combining Epigenetic and Immunotherapy to Combat Cancer

The most exciting recent advance for achieving durable management of advanced human cancers is immunotherapy, especially the concept of immune checkpoint blockade. However, with the exception of melanoma, most patients do not respond to immunotherapy alone. A growing body of work has shown that epigenetic drugs, specifically DNA methyltransferase inhibitors, can upregulate immune signaling in epithelial cancer cells through demethylation of endogenous retroviruses and cancer testis antigens. These demethylating agents may induce T-cell attraction and enhance immune checkpoint inhibitor efficacy in mouse models. Current clinical trials are testing this combination therapy as a potent new cancer management strategy. Cancer Res; 76(7); 1683-9. ©2016 AACR.

Decitabine enhances anti-CD33 monoclonal antibody BI 836858-mediated natural killer ADCC against AML blasts

Acute myeloid leukemia (AML) is the most common type of acute leukemia, affecting older individuals at a median age of 67 years. Resistance to intensive induction chemotherapy is the major cause of death in elderly AML; hence, novel treatment strategies are warranted. CD33-directed antibody-drug conjugates (gemtuzumab ozogamicin) have been shown to improve overall survival, validating CD33 as a target for antibody-based therapy of AML. Here, we report the in vitro efficacy of BI 836858, a fully human, Fc-engineered, anti-CD33 antibody using AML cell lines and primary AML blasts as targets. BI 836858-opsonized AML cells significantly induced both autologous and allogeneic natural killer (NK)-cell degranulation and NK-cell-mediated antibody-dependent cellular cytotoxicity (ADCC). In vitro treatment of AML blasts with decitabine (DAC) or 5-azacytidine, 2 hypomethylating agents that show efficacy in older patients, did not compromise BI 836858-induced NK-cell-mediated ADCC. Evaluation of BI 836858-mediated ADCC in serial marrow AML aspirates in patients who received a 10-day course of DAC (pre-DAC, days 4, 11, and 28 post-DAC) revealed significantly higher ADCC in samples at day 28 post-DAC when compared with pre-DAC treatment. Analysis of ligands to activating receptors (NKG2D) showed significantly increased NKG2D ligand [NKG2DL] expression in day 28 post-DAC samples compared with pre-DAC samples; when NKG2DL receptor was blocked using antibodies, BI 836858-mediated ADCC was significantly decreased, suggesting that DAC enhances AML blast susceptibility to BI 836858 by upregulating NKG2DL. These data provide a rationale for combination therapy of Fc-engineered antibodies such as BI 836858 with azanucleosides in elderly patients with AML.

Tumor-reactive immune cells protect against metastatic tumor and induce immunoediting of indolent but not quiescent tumor cells

Quiescent, but not indolent, dormant tumor cells are resistant to immunoediting, and best targets for immunotherapy of cancer.

Two major barriers to cancer immunotherapy include tumor-induced immune suppression mediated by myeloid-derived suppressor cells and poor immunogenicity of the tumor-expressing self-antigens. To overcome these barriers, we reprogrammed tumor-immune cell cross-talk by combined use of decitabine and adoptive immunotherapy, containing tumor-sensitized T cells and CD25⁺ NKT cells. Decitabine functioned to induce the expression of highly immunogenic cancer testis antigens in the tumor, while also reducing the frequency of myeloid-derived suppressor cells and the presence of CD25⁺ NKT cells rendered T cells, resistant to remaining myeloid-derived suppressor cells. This combinatorial therapy significantly prolonged survival of animals bearing metastatic tumor cells. Adoptive immunotherapy also induced tumor immunoediting, resulting in tumor escape and associated disease-related mortality. To identify a tumor target that is incapable of escape from the immune response, we used dormant tumor cells. We used Adriamycin chemotherapy or radiation therapy, which simultaneously induce tumor cell death and tumor dormancy. Resultant dormant cells became refractory to additional doses of Adriamycin or radiation therapy, but they remained sensitive to tumor-reactive immune cells. Importantly, we discovered that dormant tumor cells contained indolent cells that expressed low levels of Ki67 and quiescent cells that were Ki67 negative. Whereas the former were prone to tumor immunoediting and escape, the latter did not demonstrate immunoediting. Our results suggest that immunotherapy could be highly effective against quiescent dormant tumor cells. The challenge is to develop combinatorial therapies that could establish a quiescent type of tumor dormancy, which would be the best target for immunotherapy.

A promising sword of tomorrow: Human γδ T cell strategies reconcile allo-HSCT complications

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is potentially a curative therapeutic option for hematological malignancies. In clinical practice, transplantation associated complications greatly affected the final therapeutical outcomes. Currently, primary disease relapse, graft-versus-host disease (GVHD) and infections remain the three leading causes of a high morbidity and mortality in allo-HSCT patients. Various strategies have been investigated in the past several decades including human γδ T cell-based therapeutical regimens. In different microenvironments, human γδ T cells assume features reminiscent of classical Th1, Th2, Th17, NKT and regulatory T cells, showing diverse biological functions. The cytotoxic γδ T cells could be utilized to target relapsed malignancies, and recently regulatory γδ T cells are defined as a novel implement for GVHD management. In addition, human γδ Τ cells facilitate control of post-transplantation infections and participate in tissue regeneration and wound healing processes. These features potentiate γδ T cells a versatile therapeutical agent to target transplantation associated complications. This review focuses on insights of applicable potentials of human γδ T cells reconciling complications associated with allo-HSCT. We believe an improved understanding of pertinent γδ T cell functions would be further exploited in the design of innovative immunotherapeutic approaches in allo-HSCT, to reduce mortality and morbidity, as well as improve quality of life for patients after transplantation.

Augmenting antitumor immune responses with epigenetic modifying agents

Epigenetic silencing of immune-related genes is a striking feature of the cancer genome that occurs in the process of tumorigenesis. This phenomena impacts antigen processing and antigen presentation by tumor cells and facilitates evasion of immunosurveillance. Further modulation of the tumor microenvironment by altered expression of immunosuppressive cytokines impairs antigen-presenting cells and cytolytic T-cell function. The potential reversal of immunosuppression by epigenetic modulation is therefore a promising and versatile therapeutic approach to reinstate endogenous immune recognition and tumor lysis. Pre-clinical studies have identified multiple elements of the immune system that can be modulated by epigenetic mechanisms and result in improved antigen presentation, effector T-cell function, and breakdown of suppressor mechanisms. Recent clinical studies are utilizing epigenetic therapies prior to, or in combination with, immune therapies to improve clinical outcomes.

Low-dose decitabine-based chemoimmunotherapy for patients with refractory advanced solid tumors: a phase I/II report

Aberrant DNA methylation is one of the main drivers of tumor initiation and progression. The reversibility of methylation modulation makes it an attractive target for novel anticancer therapies. Clinical studies have demonstrated that high-dose decitabine, a hypomethylating agent, results in some clinical benefits in patients with refractory advanced tumors; however, they are extremely toxic. Low doses of decitabine minimize toxicity while potentially improving the targeted effects of DNA hypomethylation. Based on these mechanisms, low-dose decitabine combined with chemoimmunotherapy may be a new treatment option for patients with refractory advanced tumors. We proposed the regimen of low-dose decitabine-based chemoimmunotherapy for patients with refractory advanced solid tumors. A favorable adverse event profile was observed in our trial that was highlighted by the finding that most of these adverse events were grades 1-2. Besides, the activity of our cohort was optimistic and the clinical benefit rate was up to 60%, and the median PFS was prolonged compared with PFS to previous treatment. We also identified a significant correlation between the PFS to previous treatment and clinical response. The low-dose DAC decitabine-based chemoimmunotherapy might be a promising protocol for improving the specificity and efficiency of patients with refractory advanced solid tumors. This trial is registered in the ClinicalTrials.gov database (identifier NCT01799083).

Cancer-Induced Alterations of NK-Mediated Target Recognition: Current and Investigational Pharmacological Strategies Aiming at Restoring NK-Mediated Anti-Tumor Activity

Despite evidence of cancer immune-surveillance, which plays a key role in tumor rejection, cancer cells can escape immune recognition through different mechanisms. Thus, evasion to Natural killer (NK) cell-mediated anti-tumor activity is commonly described and is mediated by various mechanisms, mainly cancer cell-induced down-regulation of NK-activating receptors (NCRs, NKG2D, DNAM-1, and CD16) as well as up-regulation of inhibitory receptors (killer-cell immunoglobulin-like receptors, KIRs, NKG2A). Alterations of NK cells lead to an impaired recognition of tumor cells as well as a decreased ability to interact with immune cells. Alternatively, cancer cells downregulate expression of ligands for NK cell-activating receptors and up-regulate expression of the ligands for inhibitory receptors. A better knowledge of the extent and the mechanisms of these defects will allow developing pharmacological strategies to restore NK cell ability to recognize and lyse tumor cells. Combining conventional chemotherapy and immune modulation is a promising approach likely to improve clinical outcome in diverse neoplastic malignancies. Here, we overview experimental approaches as well as strategies already available in the clinics that restore NK cell functionality. Yet successful cancer therapies based on the manipulation of NK cell already have shown efficacy in the context of hematologic malignancies. Additionally, the ability of cytotoxic agents to increase susceptibility of tumors to NK cell lysis has been studied and may require improvement to maximize this effect. More recently, new strategies were developed to specifically restore NK cell phenotype or to stimulate NK cell functions. Overall, pharmacological immune modulation trends to be integrated in therapeutic strategies and should improve anti-tumor effects of conventional cancer therapy.

Natural killer cells modulation in hematological malignancies

Hematological malignancies (HM) treatment improved over the last years resulting in increased achievement of complete or partial remission, but unfortunately high relapse rates are still observed, due to remaining minimal residual disease. Therefore, sustainment of long-term remission is crucial, using either drug maintenance treatment or by boosting or prolonging an immune response. Immune system has a key role in tumor surveillance. Nonetheless, tumor-cells evade the specific T-lymphocyte mediated immune surveillance using many mechanisms but especially by the down-regulation of the expression of HLA class I antigens. In theory, these tumor-cells lacking normal expression of HLA class I molecules should be destroyed by natural killer (NK) cells, according to the missing-self hypothesis. NK cells, at the frontier of innate and adaptive immune system, have a central role in tumor-cells surveillance as demonstrated in the setting of allogenic stem cell transplantation. Nevertheless, tumors develop various mechanisms to escape from NK innate immune pressure. Abnormal NK cytolytic functions have been described in many HM. We present here various mechanisms involved in the escape of HM from NK-cell surveillance, i.e., NK-cells quantitative and qualitative abnormalities.

Epigenetic modifications during sex change repress gonadotropin stimulation of cyp19a1a in a teleost ricefield eel (Monopterus albus)

In vertebrates, cytochrome P450 aromatase, encoded by cyp19a1, converts androgens to estrogens and plays important roles in gonadal differentiation and development. The present study examines whether epigenetic mechanisms are involved in cyp19a1a expression and subsequent gonadal development in the hermaphroditic ricefield eel. The expression of the ricefield eel cyp19a1a was stimulated by gonadotropin via the cAMP pathway in the ovary but not the ovotestis or testis. The CpG within the cAMP response element (CRE) of the cyp19a1a promoter was hypermethylated in the ovotestis and testis compared with the ovary. The methylation levels of CpG sites around CRE in the distal region (region II) and around steroidogenic factor 1/adrenal 4 binding protein sites and TATA box in the proximal region (region I) were inversely correlated with cyp19a1a expression during the natural sex change from female to male. In vitro DNA methylation decreased the basal and forskolin-induced activities of cyp19a1a promoter. Chromatin immunoprecipitation assays indicated that histone 3 (Lys9) in both regions I and II of the cyp19a1a promoter were deacetylated and trimethylated in the testis, and in contrast to the ovary, phosphorylated CRE-binding protein failed to bind to these regions. Lastly, the DNA methylation inhibitor 5-aza-2'-deoxycytidine reversed the natural sex change of ricefield eels. These results suggested that epigenetic mechanisms involving DNA methylation and histone deacetylation and methylation may abrogate the stimulation of cyp19a1a by gonadotropins in a male-specific fashion. This may be a mechanism widely used to drive natural sex change in teleosts as well as gonadal differentiation in other vertebrates.

Influence of Histone Deacetylase Inhibitors and DNA-Methyltransferase Inhibitors on the NK Cell-Mediated Lysis of Pediatric B-Lineage Leukemia

Epigenetic drugs like histone deacetylase inhibitors (HDACi) and DNA-methyltransferase inhibitors (DNMTi) have been shown to be effective against a variety of tumor entities. Among different molecular anticancer activities of epigenetic active substances, up-regulation of natural killer (NK) cell ligands was described to contribute to an enhanced NK cell-mediated killing of tumor cell lines. So far, no data is available on this effect in childhood acute lymphoblastic leukemia. We investigated the effect of two HDACi [vorinostat, valproic acid (VPA)] and two DNMTi (azacytidine, decitabine) on the viability, expression of NK ligands, and NK susceptibility of the pre-B-cell-ALL cell line MHH-CALL-4. Whereas vorinostat, azacytidine, and decitabine directly reduced viability of the cell line, VPA had no direct cytotoxic effect. NKG2D-ligands were expressed only at very low levels and not affected by epigenetic treatment. Higher expression was found for the DNAM-1 ligands with significant up regulation of CD112 after treatment with VPA (p = 0.02). No significant increase in lysis mediated by resting NK cells could be observed, whereas incubation of target cells with decitabine resulted in a significant increase in lysis mediated by IL-2 activated NK cells (p = 0.0051, p = 0.06 for azacytidine). Vorinostat and VPA could increase the lysis by expanded NK cells which was statistically not significant due to high inter-individual variability. Furthermore, HDACi but not DNMTi reduced the NK-mediated lysis of MHH-CALL-4 after incubation of effector cells. In conclusion, there is a synergistic effect between epigenetic drugs and NK cells against MHH-CALL-4 which is not as strong as in other tumor entities. In situations where NK-mediated control of leukemia is assumed or wanted, a sophisticated combination of single epigenetic drugs and ex vivo expanded NK cells is needed to maximize the synergistic effect of both treatment strategies and DNMTIs may be preferred based on the direct inhibitory effect of HDACi on NK cell cytotoxicity.