Targeting the epigenome for treatment of cancer

H3K56 deacetylation and H2A.Z deposition are required for aberrant heterochromatin spreading

Crucial mechanisms are required to restrict self-propagating heterochromatin spreading within defined boundaries and prevent euchromatic gene silencing. In the filamentous fungus Neurospora crassa, the JmjC domain protein DNA METHYLATION MODULATOR-1 (DMM-1) prevents aberrant spreading of heterochromatin, but the molecular details remain unknown. Here, we revealed that DMM-1 is highly enriched in a well-defined 5-kb heterochromatin domain upstream of the cat-3 gene, hereby called 5H-cat-3 domain, to constrain aberrant heterochromatin spreading. Interestingly, aberrant spreading of the 5H-cat-3 domain observed in the dmm-1^KO strain is accompanied by robust deposition of histone variant H2A.Z, and deletion of H2A.Z abolishes aberrant spreading of the 5H-cat-3 domain into adjacent euchromatin. Furthermore, lysine 56 of histone H3 is deacetylated at the expanded heterochromatin regions, and mimicking H3K56 acetylation with an H3K56Q mutation effectively blocks H2A.Z-mediated aberrant spreading of the 5H-cat-3 domain. Importantly, genome-wide analyses demonstrated the general roles of H3K56 deacetylation and H2A.Z deposition in aberrant spreading of heterochromatin. Together, our results illustrate a previously unappreciated regulatory process that mediates aberrant heterochromatin spreading.

Identification of Four Enhancer-Associated Genes as Risk Signature for Diffuse Glioma Patients

The abnormal expressions of enhancer-associated genes have been reported to be correlated with poor prognosis of tumors, including glioblastoma (GBM). The objective of the current study is to predict prognosis by identifying enhancer-associated genes (EAGs). The profiles of genome-wide expressions of low-grade glioma (LGG) and GBM tissues in The Cancer Genome Atlas (TCGA) dataset were obtained to explore the expression patterns of EAGs in diffuse glioma. The capacity of prognosis prediction was validated by Rembrandt and GSE16011. Moreover, qPCR was utilized to confirm the effect of JQ1 and THZ1 on the EAGs. We detected 35 differentially expressed EAGs, which were predictive of overall survival. These candidate EAGs were then subjected to the multivariate cox regression analysis and were further scoped down to four signature genes, including TRAM2, SMAGP, KDELC2, and C7ORF25. A total of 662 patients were then stratified according to the expression levels of these four signature genes. The high-risk group accounted for poorer prognosis based on the Rembrandt and GSE16011 databases. The results of qPCR also demonstrated that the expression of the four EAGs could be abolished by JQ1 (bromodomain inhibitor) and THZ1 (CDK7 inhibitor) treatment. Our study not only highlights the potential role of EAGs, which can be used to improve clinical prognosis prediction in patients with diffuse glioma, but also sheds light on the specific biomarkers and therapeutic targets for diffuse glioma patients.

CRISPR/Cas mediated epigenome editing for cancer therapy

The understanding of the relationship between epigenetic alterations, their effects on gene expression and the knowledge that these epigenetic alterations are reversible, have opened up new therapeutic pathways for treating various diseases, including cancer. This has led the research for a better understanding of the mechanism and pathways of carcinogenesis and provided the opportunity to develop the therapeutic approaches by targeting such pathways. Epi-drugs, DNA methyl transferase (DNMT) inhibitors and histone deacetylase (HDAC) inhibitors are the best examples of epigenetic therapies with clinical applicability. Moreover, precise genome editing technologies such as CRISPR/Cas has proven their efficacy in epigenome editing, including the alteration of epigenetic markers, such as DNA methylation or histone modification. The main disadvantage with DNA gene editing technologies is off-target DNA sequence alteration, which is not an issue with epigenetic editing. It is known that cancer is linked with epigenetic alteration, and thus CRISPR/Cas system shows potential for cancer therapy via epigenome editing. This review outlines the epigenetic therapeutic approach for cancer therapy using CRISPR/Cas, from the basic understanding of cancer epigenetics to potential applications of CRISPR/Cas in treating cancer.

Osirisynes G-I, New Long-Chain Highly Oxygenated Polyacetylenes from the Mayotte Marine Sponge Haliclona sp

Chemical study of the CH2Cl2−MeOH (1:1) extract from the sponge Haliclona sp. collected in Mayotte highlighted three new long-chain highly oxygenated polyacetylenes, osirisynes G-I (1–3) together with the known osirisynes A (4), B (5), and E (6). Their structures were elucidated by 1D and 2D NMR spectra and HRESIMS and MS/MS data. All compounds were evaluated on catalase and sirtuin 1 activation and on CDK7, proteasome, Fyn kinase, tyrosinase, and elastase inhibition. Five compounds (1; 3–6) inhibited proteasome kinase and two compounds (5–6) inhibited CDK7 and Fyn kinase. Osirisyne B (5) was the most active compound with IC₅₀ on FYNB kinase, CDK7 kinase, and proteasome inhibition of 18.44 µM, 9.13 µM, and 0.26 µM, respectively.

Super-enhancers in transcriptional regulation and genome organization

Gene expression is precisely controlled in a stage and cell-type-specific manner, largely through the interaction between cis-regulatory elements and their associated trans-acting factors. Where these components aggregate in promoters and enhancers, they are able to cooperate to modulate chromatin structure and support the engagement in long-range 3D superstructures that shape the dynamics of a cell's genomic architecture. Recently, the term 'super-enhancer' has been introduced to describe a hyper-active regulatory domain comprising a complex array of sequence elements that work together to control the key gene networks involved in cell identity. Here, we survey the unique characteristics of super-enhancers compared to other enhancer types and summarize the recent advances in our understanding of their biological role in gene regulation. In particular, we discuss their capacity to attract the formation of phase-separated condensates, and capacity to generate three-dimensional genome structures that precisely activate their target genes. We also propose a multi-stage transition model to explain the evolutionary pressure driving the development of super-enhancers in complex organisms, and highlight the potential for involvement in tumorigenesis. Finally, we discuss more broadly the role of super-enhancers in human health disorders and related potential in therapeutic interventions.

Unprogrammed epigenetic variation mediated by stochastic formation of ectopic heterochromatin

Changes in gene expression via chromatin-mediated mechanisms are important for reprogramming and differentiation, but uncontrolled changes can potentially lead to harmful or adaptive phenotypic alteration. Thus, diversification of the genome-wide chromatin state must be strictly limited, but the underlying mechanism of this regulation is largely unknown. In this review, we focused on distribution of heterochromatin, a tight chromatin structure that negatively regulates gene expression. Heterochromatin is characterized by methylation of histone H3 at lysine 9, and its formation and spreading are controlled by H3K9-specific methyltransferases and reversal factors such as histone demethylases. We summarize recent findings and discuss how variability in the heterochromatin distribution is controlled in the unicellular eukaryote fission yeast. In this context, we recently found that the anti-silencing factor Epe1 plays a key role in the formation of the individual-specific heterochromatin distribution. In conclusion, recent studies revealed that there are many potential heterochromatin formation sites in the fission yeast genome, and several proteins contribute to suppression of spreading and genome-wide dispersal of heterochromatin; knowledge from fission yeast studies may provide insights into the mechanisms regulating epigenetic diversification in multicellular eukaryotes.

BRD4 interacts with PML/RARα in acute promyelocytic leukemia

Bromodomain-containing 4 (BRD4) has been considered as an important requirement for disease maintenance and an attractive therapeutic target for cancer therapy. This protein can be targeted by JQ1, a selective small-molecule inhibitor. However, few studies have investigated whether BRD4 influenced acute promyelocytic leukemia (APL), and whether BRD4 had interaction with promyelocytic leukemia-retinoic acid receptor α (PML/RARα) fusion protein to some extent. Results from cell viability assay, cell cycle analysis, and Annexin-V/PI analysis indicated that JQ1 inhibited the growth of NB4 cells, an APL-derived cell line, and induced NB4 cell cycle arrest at G1 and apoptosis. Then, we used co-immunoprecipitation (co-IP) assay and immunoblot to demonstrate the endogenous interaction of BRD4 and PML/RARα in NB4 cells. Moreover, downregulation of PML/RARα at the mRNA and protein levels was observed upon JQ1 treatment. Furthermore, results from the RT-qPCR, ChIP-qPCR, and re-ChIP-qPCR assays showed that BRD4 and PML/RARα co-existed on the same regulatory regions of their target genes. Hence, we showed a new discovery of the interaction of BRD4 and PML/RARα, as well as the decline of PML/RARα expression, under JQ1 treatment.

What's in the "fold"?

Complexity in genome architecture determines how gene expression programs are established, maintained, and modified from early developmental stages to normal adult phenotypes. Large scale and hierarchical organization of the genome impacts various aspects of cell functions, ranging from X-chromosome inactivation, stem-cell fate determination to transcription, DNA replication, and cellular repair. While chromatin loops and topologically-associated domains represent a basic structural or fundamental unit of chromatin organization, spatio-temporal organization of the genome further creates a complex network of interacting genome patterns, forming chromosomal compartments and chromosome territories. The understanding of human diseases, including cancers, auto-immune disorders, Alzheimer's, and cardiovascular diseases, relies on the associated molecular and epigenetic mechanisms. There is a growing interest in the impact of three-dimensional chromatin folding upon the genome structure and function, which gives rise to the question "What's in the fold?" and is the main focus of this review. Here we discuss the principles determining the spatial and regulatory relationships between gene regulation and three-dimensional chromatin landscapes, and how changes in chromatin-folding could influence the outcome of genome function in healthy and disease states.

Environmental Carcinogenesis and Transgenerational Transmission of Carcinogenic Risk: From Genetics to Epigenetics

The dominant pathogenic model, somatic mutation theory (SMT), considers carcinogenesis as a ‘genetic accident’ due to the accumulation of ‘stochastic’ DNA mutations. This model was proposed and accepted by the scientific community when cancer mainly affected the elderly, but it does not explain the epidemiological observation of the continuous increase in cancer incidence among children and young adults. Somatic mutation theory has been proposed for a revision based on the emerging experimental evidence, as it does not fully address some issues that have proven to be crucial for carcinogenesis, namely: the inflammatory context of cancer; the key role played by the stroma, microenvironment, endothelial cells, activated macrophages, and surrounding tissues; and the distorted developmental course followed by the neoplastic tissue. Furthermore, SMT is often not able to consider either the existence of specific mutations resulting in a well-defined cancer type, or a clear relationship between mutations and tumor progression. Moreover, it does not explain the mechanism of action of the non-mutagenic and environmental carcinogens. In the last decade, cancer research has highlighted the prominent role of an altered regulation of gene expression, suggesting that cancer should be considered as a result of a polyclonal epigenetic disruption of stem/progenitor cells, mediated by tumour-inducing genes. The maternal and fetal exposure to a wide range of chemicals and environmental contaminants is raising the attention of the scientific community. Indeed, the most powerful procarcinogenic mechanisms of endocrine disruptors and other pollutants is linked to their potential to interfere epigenetically with the embryo-fetal programming of tissues and organs, altering the regulation of the genes involved in the cell cycle, cell proliferation, apoptosis, and other key signaling pathways. The embryo-fetal exposure to environmental, stressful, and proinflammatory triggers (first hit), seems to act as a ‘disease primer’, making fetal cells and tissues more susceptible to the subsequent environmental exposures (second hit), triggering the carcinogenic pathways. Furthermore, even at the molecular level, in carcinogenesis, ‘epigenetics precedes genetics’ as global DNA hypomethylation, and the hypermethylation of tumor suppressor genes are common both in cancerous and in precancerous cells, and generally precede mutations. These epigenetic models may better explain the increase of cancer and chronic/degenerative diseases in the last decades and could be useful to adopt appropriate primary prevention measures, essentially based on the reduction of maternal-fetal and child exposure to several procarcinogenic agents and factors dispersed in the environment and in the food-chains, as recently suggested by the World Health Organization.

MicroRNA-495-3p functions as a tumor suppressor by regulating multiple epigenetic modifiers in gastric carcinogenesis

MicroRNAs (miRNAs) engage in complex interactions with the machinery that controls the transcriptome and concurrently target multiple mRNAs. Here, we demonstrate that microRNA-495-3p (miR-495-3p) functions as a potent tumor suppressor by governing ten oncogenic epigenetic modifiers (EMs) in gastric carcinogenesis. From the large cohort transcriptome datasets of gastric cancer (GC) patients available from The Cancer Genome Atlas (TCGA) and the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO), we were able to recapitulate 15 EMs as significantly overexpressed in GC among the 51 EMs that were previously reported to be involved in cancer progression. Computational target prediction yielded miR-495-3p, which targets as many as ten of the 15 candidate oncogenic EMs. Ectopic expression of miRNA mimics in GC cells caused miR-495-3p to suppress ten EMs, and inhibited tumor cell growth and proliferation via caspase-dependent and caspase-independent cell death processing. In addition, in vitro metastasis assays showed that miR-495-3p plays a role in the metastatic behavior of GC cells by regulating SLUG, vimentin, and N-cadherin. Furthermore, treatment of GC cells with 5-aza-2'-deoxcytidine restored miR-495-3p expression; sequence analysis revealed hypermethylation of the miR-495-3p promoter region in GC cells. A negative regulatory loop is proposed, whereby DNMT1, among ten oncogenic EMs, regulates miR-495-3p expression via hypermethylation of the miR-495-3p promoter. Our findings suggest that the functional loss or suppression of miR-495-3p triggers overexpression of multiple oncogenic EMs, and thereby contributes to malignant transformation and growth of gastric epithelial cells. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Synthetic Lethality in Cancer Therapeutics

Treatment with targeted drugs has primarily focused on the genes and pathways that are mutated in cancer, which severely limits the repertoire of drug targets. Synthetic lethality exploits the notion that the presence of a mutation in a cancer gene is often associated with a new vulnerability that can be targeted therapeutically, thus greatly expanding the arsenal of potential drug targets. Here we discuss both the experimental and the computational biology tools that can be used to identify synthetic lethal interactions. We also discuss strategies for using synthetic lethality to discover new drug targets and in the rational design of more potent drug combinations. We review the progress made and future opportunities offered by synthetic lethal approaches to treating cancer more effectively.

Generalized nucleation and looping model for epigenetic memory of histone modifications

Histone modifications can redistribute along the genome in a sequence-independent manner, giving rise to chromatin position effects and epigenetic memory. The underlying mechanisms shape the endogenous chromatin landscape and determine its response to ectopically targeted histone modifiers. Here, we simulate linear and looping-driven spreading of histone modifications and compare both models to recent experiments on histone methylation in fission yeast. We find that a generalized nucleation-and-looping mechanism describes key observations on engineered and endogenous methylation domains including intrinsic spatial confinement, independent regulation of domain size and memory, variegation in the absence of antagonists, and coexistence of short- and long-term memory at loci with weak and strong constitutive nucleation. These findings support a straightforward relationship between the biochemical properties of chromatin modifiers and the spatiotemporal modification pattern. The proposed mechanism gives rise to a phase diagram for cellular memory that may be generally applicable to explain epigenetic phenomena across different species.

Subsets of Visceral Adipose Tissue Nuclei with Distinct Levels of 5-Hydroxymethylcytosine

The reprogramming of cellular memory in specific cell types, and in visceral adipocytes in particular, appears to be a fundamental aspect of obesity and its related negative health outcomes. We explored the hypothesis that adipose tissue contains epigenetically distinct subpopulations of adipocytes that are differentially potentiated to record cellular memories of their environment. Adipocytes are large, fragile, and technically difficult to efficiently isolate and fractionate. We developed fluorescence nuclear cytometry (FNC) and fluorescence activated nuclear sorting (FANS) of cellular nuclei from visceral adipose tissue (VAT) using the levels of the pan-adipocyte protein, peroxisome proliferator-activated receptor gamma-2 (PPARg2), to distinguish classes of PPARg2-Positive (PPARg2-Pos) adipocyte nuclei from PPARg2-Negative (PPARg2-Neg) leukocyte and endothelial cell nuclei. PPARg2-Pos nuclei were 10-fold enriched for most adipocyte marker transcripts relative to PPARg2-Neg nuclei. PPARg2-Pos nuclei showed 2- to 50-fold higher levels of transcripts encoding most of the chromatin-remodeling factors assayed, which regulate the methylation of histones and DNA cytosine (e.g., DNMT1, TET1, TET2, KDM4A, KMT2C, SETDB1, PAXIP1, ARID1A, JMJD6, CARM1, and PRMT5). PPARg2-Pos nuclei were large with decondensed chromatin. TAB-seq demonstrated 5-hydroxymethylcytosine (5hmC) levels were remarkably dynamic in gene bodies of various classes of VAT nuclei, dropping 3.8-fold from the highest quintile of expressed genes to the lowest. In short, VAT-derived adipocytes appear to be more actively remodeling their chromatin than non-adipocytes.

Epigenetic therapy for solid tumors: from bench science to clinical trials

The cancer epigenome is characterized by global DNA methylation and chromatin changes, such as the hypermethylation of specific CpG island promoters. Epigenetic agents like DNA methyltransferase or histone deacetylase inhibitors induce phenotype changes by reactivation of epigenetically silenced tumor suppressor genes. Despite initial promise in hematologic malignancies, epigenetic agents have not shown significant efficacy as monotherapy against solid tumors. Recent trials showed that epigenetic agents exert favorable modifier effects when combined with chemotherapy, hormonal therapy, or other epigenetic agents. Due to the novel nature of their mechanism, it is important to reconsider the optimal patient selection, drug regimen, study design, and outcome measures when pursuing future trials in order to discover the full potential of this new therapeutic modality.

Multiple Molecular Pathways in Melanomagenesis: Characterization of Therapeutic Targets

Molecular mechanisms involved in pathogenesis of malignant melanoma have been widely studied and novel therapeutic treatments developed in recent past years. Molecular targets for therapy have mostly been recognized in the RAS–RAF–MEK–ERK and PI3K–AKT signaling pathways; small-molecule inhibitors were drawn to specifically target key kinases. Unfortunately, these targeted drugs may display intrinsic or acquired resistance and various evidences suggest that inhibition of a single effector of the signal transduction cascades involved in melanoma pathogenesis may be ineffective in blocking the tumor growth. In this sense, a wider comprehension of the multiple molecular alterations accounting for either response or resistance to treatments with targeted inhibitors may be helpful in assessing, which is the most effective combination of such therapies. In the present review, we summarize the known molecular mechanisms underlying either intrinsic and acquired drug resistance either alternative roads to melanoma pathogenesis, which may become targets for innovative anticancer approaches.

Epigenetic silencing of GDF1 disrupts SMAD signaling to reinforce gastric cancer development

Accumulating evidence reveals the effectiveness of epigenetic therapy in gastric cancer. However, the molecular mechanisms and targets underlying such therapeutic responses remain elusive. Herein, we report an aberrant yet therapeutically rectifiable epigenetic signaling in gastric carcinogenesis. Administration of DNA-demethylating drug 5-aza-2'-deoxycytidine (5-aza-dC) reduced gastric cancer incidence by ~74% (P < 0.05) in N-nitroso-N-methylurea-treated mice. Through genome-wide methylation scanning, novel promoter hypermethylation-silenced and drug-targeted genes were identified in the resected murine stomach tumors and tissues. We uncovered that growth/differentiation factor 1 (Gdf1), a member of the transforming growth factor-β superfamily, was silenced by promoter hypermethylation in control tumor-bearing mice, but became reactivated in 5-aza-dC-treated mice (P < 0.05). In parallel, the downregulated SMAD2/3 phosphorylation in gastric cancer was revived by 5-aza-dC in vivo. Such hypermethylation-dependent silencing and 5-aza-dC-mediated reactivation of GDF1-SMAD2/3 activity was conserved in human gastric cancer cells (P < 0.05). Subsequent functional characterization further revealed the antiproliferative activity of GDF1, which was exerted through activation of SMAD2/3/4-mediated signaling, transcriptional controls on p15, p21 and c-Myc cell-cycle regulators and phosphorylation of retinoblastoma protein. Clinically, hypermethylation and loss of GDF1 was significantly associated with reduced phosphorylated-SMAD2/3 and poor survival in stomach cancer patients (P < 0.05). Taken together, we demonstrated a causal relationship between DNA methylation and a tumor-suppressive pathway in gastric cancer. Epigenetic silencing of GDF1 abrogates the growth-inhibitory SMAD signaling and renders proliferation advantage to gastric epithelial cells during carcinogenesis. This study lends support to epigenetic therapy for gastric cancer chemoprevention and identifies a potential biomarker for prognosis.

Increased H3K9me3 drives dedifferentiated phenotype via KLF6 repression in liposarcoma

Liposarcoma (LPS) can be divided into 4 different subtypes, of which well-differentiated LPS (WDLPS) and dedifferentiated LPS (DDLPS) are the most common. WDLPS is typically low grade, whereas DDLPS is high grade, aggressive, and carries a worse prognosis. WDLPS and DDLPS frequently co-occur in patients. However, it is not clear whether DDLPS arises independently from WDLPS, or whether epigenomic alterations underly the histopathological differences of these subtypes. Here, we profiled 9 epigenetic marks in tumor samples from 151 patients with LPS and showed elevated trimethylation of histone H3 at Lys9 (H3K9me3) levels in DDLPS tumors. Integrated ChIP-seq and gene expression analyses of patient-derived cell lines revealed that H3K9me3 mediates differential regulation of genes involved in cellular differentiation and migration. Among these, Kruppel-like factor 6 (KLF6) was reduced in DDLPS, with increased H3K9me3 at associated regulatory regions. Pharmacologic inhibition of H3K9me3 with chaetocin decreased DDLPS proliferation and increased expression of the adipogenesis-associated factors PPARγ, CEBPα, and CEBPβ, suggesting that increased H3K9me3 may mediate DDLPS-associated aggressiveness and dedifferentiation properties. KLF6 overexpression partially phenocopied chaetocin treatment in DDLPS cells and induced phenotypic changes that were consistent with adipocytic differentiation, suggesting that the effects of increased H3K9me3 may be mediated through KLF6. In conclusion, we provide evidence of an epigenetic basis for the transition between WDLPS and DDLPS.

The SMARCA2/4 ATPase Domain Surpasses the Bromodomain as a Drug Target in SWI/SNF-Mutant Cancers: Insights from cDNA Rescue and PFI-3 Inhibitor Studies

The SWI/SNF multisubunit complex modulates chromatin structure through the activity of two mutually exclusive catalytic subunits, SMARCA2 and SMARCA4, which both contain a bromodomain and an ATPase domain. Using RNAi, cancer-specific vulnerabilities have been identified in SWI/SNF-mutant tumors, including SMARCA4-deficient lung cancer; however, the contribution of conserved, druggable protein domains to this anticancer phenotype is unknown. Here, we functionally deconstruct the SMARCA2/4 paralog dependence of cancer cells using bioinformatics, genetic, and pharmacologic tools. We evaluate a selective SMARCA2/4 bromodomain inhibitor (PFI-3) and characterize its activity in chromatin-binding and cell-functional assays focusing on cells with altered SWI/SNF complex (e.g., lung, synovial sarcoma, leukemia, and rhabdoid tumors). We demonstrate that PFI-3 is a potent, cell-permeable probe capable of displacing ectopically expressed, GFP-tagged SMARCA2-bromodomain from chromatin, yet contrary to target knockdown, the inhibitor fails to display an antiproliferative phenotype. Mechanistically, the lack of pharmacologic efficacy is reconciled by the failure of bromodomain inhibition to displace endogenous, full-length SMARCA2 from chromatin as determined by in situ cell extraction, chromatin immunoprecipitation, and target gene expression studies. Furthermore, using inducible RNAi and cDNA complementation (bromodomain- and ATPase-dead constructs), we unequivocally identify the ATPase domain, and not the bromodomain of SMARCA2, as the relevant therapeutic target with the catalytic activity suppressing defined transcriptional programs. Taken together, our complementary genetic and pharmacologic studies exemplify a general strategy for multidomain protein drug-target validation and in case of SMARCA2/4 highlight the potential for drugging the more challenging helicase/ATPase domain to deliver on the promise of synthetic-lethality therapy.

Opportunities and challenges provided by crosstalk between signalling pathways in cancer

During evolution, connections between the major signalling pathways were established to provide cells with an ability to deal with perturbations of homeostasis. However, these feedback and crosstalk mechanisms can become a liability in the treatment of cancer, as the inhibition of one cancer-relevant signalling pathway can lead to the activation of a secondary survival pathway that interferes with cancer drug efficacy. In this review, we discuss connections between signalling pathways in relation to cancer therapy and we evaluate the use of genetic approaches to identify pathway crosstalk. We also discuss how insight into connections between signalling pathways can be exploited to design powerful synthetic lethal drug combination therapies for the treatment of cancer.

Targeted inhibition of genome-wide DNA methylation analysis in epigenetically modulated phenotypes in lung cancer

DNA methylation analysis, an epigenetic specification, has been explored for partial determination of cancer cell phenotypes. The development of metastasis in cancerogenesis has led its feasible association with the epigenetic modulations. We generated highly aggressive non-small cell lung cancer cell lines (HTB56 and A549) by using in vivo selection approach. These were, then, subjected to DNA methylation analysis (genome-wide). We also explored the therapeutic effects of azacytidine, an epigenetic agent, on DNA methylation patterns as well as the in vivo phenotypes. During the development of highly aggressive cell lines, we observed widespread modulations in DNA methylation. Reduced representation bisulfite sequencing was used and compared with the less aggressive parental cell lines to identify the differential methylation, which was achieved up to 2.7 % of CpG-rich region. Azacytidine inhibited DNA methyltransferase and reversed the prometastatic phenotype. We found its high association with the preferential loss of DNA methylation from hypermethylated sites. After persisted exposure of azacytidine, we observed that DNA methylation affected the polycomb-binding sites. We found close association of DNA methylome modifications with metastatic capability of non-small cell lung cancer. We also concluded that epigenetic modulation could be used as a potential therapeutic approach to prevent metastasis formation as prometastatic phenotype was reversed due to inhibition of DNA methyltransferase.

The BET Bromodomain Inhibitor OTX015 Affects Pathogenetic Pathways in Preclinical B-cell Tumor Models and Synergizes with Targeted Drugs

PURPOSE

In cancer cells, the epigenome is often deregulated, and inhibition of the bromodomain and extra-terminal (BET) family of bromodomain-containing proteins is a novel epigenetic therapeutic approach. Preliminary results of an ongoing phase I trial have reported promising activity and tolerability with the new BET bromodomain inhibitor OTX015.

EXPERIMENTAL DESIGN

We assessed the preclinical activity of OTX015 as single agent and in combination in mature B-cell lymphoma models and performed in vitro and in vivo experiments to identify the mechanism of action and the genetic features associated with sensitivity to the compound.

RESULTS

OTX015 showed antiproliferative activity in a large panel of cell lines derived from mature B-cell lymphoid tumors with median IC50 of 240 nmol/L, without significant differences among the different histotypes. In vitro and in vivo experiments showed that OTX015 targeted NFKB/TLR/JAK/STAT signaling pathways, MYC- and E2F1-regulated genes, cell-cycle regulation, and chromatin structure. OTX015 presented in vitro synergism with several anticancer agents, especially with mTOR and BTK inhibitors. Gene expression signatures associated with different degrees of sensitivity to OTX015 were identified. Although OTX015 was mostly cytostatic, the compound induced apoptosis in a genetically defined subgroup of cells, derived from activated B-cell-like diffuse large B-cell lymphoma, bearing wtTP53, mutations in MYD88, and CD79B or CARD11.

CONCLUSIONS

Together with the data coming from the ongoing phase I study, the in vitro and in vivo data presented here provide the basis for further clinical investigation of OTX015 as single agent and in combination therapies.

Rapid epigenetic adaptation to uncontrolled heterochromatin spreading

Heterochromatin, a highly compact chromatin state characterized by histone H3K9 methylation and HP1 protein binding, silences the underlying DNA and influences the expression of neighboring genes. However, the mechanisms that regulate heterochromatin spreading are not well understood. In this study, we show that the conserved Mst2 histone acetyltransferase complex in fission yeast regulates histone turnover at heterochromatin regions to control heterochromatin spreading and prevents ectopic heterochromatin assembly. The combined loss of Mst2 and the JmjC domain protein Epe1 results in uncontrolled heterochromatin spreading and massive ectopic heterochromatin, leading to severe growth defects due to the inactivation of essential genes. Interestingly, these cells quickly recover by accumulating heterochromatin at genes essential for heterochromatin assembly, leading to their reduced expression to restrain heterochromatin spreading. Our studies discover redundant pathways that control heterochromatin spreading and prevent ectopic heterochromatin assembly and reveal a fast epigenetic adaptation response to changes in heterochromatin landscape.

DOI:http://dx.doi.org/10.7554/eLife.06179.001

The DNA in the nucleus of a cell is wrapped around histone proteins to form a compact structure known as chromatin. Chromatin's structure can control how the genes in DNA are expressed. Loosely packed chromatin contains active genes, whereas densely packed chromatin (also called ‘heterochromatin’) contains silenced genes that are not expressed. The assembly of DNA into heterochromatin needs to be carefully controlled. Otherwise, the DNA next to heterochromatin regions can become densely packed as well (via a process called ‘heterochromatin spreading’), and the genes within this DNA are incorrectly silenced. Incorrect gene silencing is often associated with diseases such as cancer.

Cells add chemical groups onto the histone proteins to influence how chromatin is compacted. Densely packed chromatin contains histones with many methyl groups but few acetyl groups. A protein called Epe1, which potentially removes methyl groups, helps to prevent heterochromatin spreading in yeast cells. Wang et al. found that an enzyme called Mst2, which adds acetyl groups onto histones, also limits heterochromatin spreading and prevents extra heterochromatin from assembling at undesirable locations.

Wang et al. then generated yeast cells that lacked both Epe1 and Mst2. At first, these cells were sickly and unable to grow, because several essential genes were incorrectly silenced due to rampant heterochromatin spreading. However, the cells quickly overcame this growth defect by gaining an additional mutation. Normally mutations occur through changes in DNA sequences. However, Wang et al. found that the cells acquired this mutation by packing a gene required for heterochromatin assembly into heterochromatin. This in turn stopped more chromatin from becoming packed too densely. Changes to chromatin can also be passed on to the yeast's offspring, and such a change could help the offspring to better cope with changes in heterochromatin levels. Future work could test how often inheritable changes to chromatin modification help organisms adapt to environmental stresses, or if similar changes allow cancer cells to become tolerant to anticancer drugs.

DOI:http://dx.doi.org/10.7554/eLife.06179.002

Altering cancer transcriptomes using epigenomic inhibitors

Background

Due to the hyper-activation of WNT signaling in a variety of cancer types, there has been a strong drive to develop pathway-specific inhibitors with the eventual goal of providing a chemotherapeutic antagonist of WNT signaling to cancer patients. A new category of drugs, called epigenetic inhibitors, are being developed that hold high promise for inhibition of the WNT pathway. The canonical WNT signaling pathway initiates when WNT ligands bind to receptors, causing the nuclear localization of the co-activator β-catenin (CTNNB1), which leads to an association of β-catenin with a member of the TCF transcription factor family at regulatory regions of WNT-responsive genes. The TCF/β-catenin complex then recruits CBP (CREBBP) or p300 (EP300), leading to histone acetylation and gene activation. A current model in the field is that CBP-driven expression of WNT target genes supports proliferation whereas p300-driven expression of WNT target genes supports differentiation. The small molecule inhibitor ICG-001 binds to CBP, but not to p300, and competitively inhibits the interaction of CBP with β-catenin. Upon treatment of cancer cells, this should reduce expression of CBP-regulated transcription, leading to reduced tumorigenicity and enhanced differentiation.

Results

We have compared the genome-wide effects on the transcriptome after treatment with ICG-001 (the specific CBP inhibitor) versus C646, a compound that competes with acetyl-coA for the Lys-coA binding pocket of both CBP and p300. We found that both drugs cause large-scale changes in the transcriptome of HCT116 colon cancer cells and PANC1 pancreatic cancer cells and reverse some tumor-specific changes in gene expression. Interestingly, although the epigenetic inhibitors affect cell cycle pathways in both the colon and pancreatic cancer cell lines, the WNT signaling pathway was affected only in the colon cancer cells. Notably, WNT target genes were similarly downregulated after treatment of HCT116 with C646 as with ICG-001.

Conclusion

Our results suggest that treatment with a general HAT inhibitor causes similar effects on the transcriptome as does treatment with a CBP-specific inhibitor and that epigenetic inhibition affects the WNT pathway in HCT116 cells and the cholesterol biosynthesis pathway in PANC1 cells.

Electronic supplementary material

The online version of this article (doi:10.1186/1756-8935-8-9) contains supplementary material, which is available to authorized users.

Histone acetyltransferase inhibitors block neuroblastoma cell growth in vivo

We have previously described novel histone acetyltransferase (HAT) inhibitors that block neuroblastoma cell growth in vitro. Here we show that two selected pyridoisothiazolone HAT inhibitors, PU139 and PU141, induce cellular histone hypoacetylation and inhibit growth of several neoplastic cell lines originating from different tissues. Broader in vitro selectivity profiling shows that PU139 blocks the HATs Gcn5, p300/CBP-associated factor (PCAF), CREB (cAMP response element-binding) protein (CBP) and p300, whereas PU141 is selective toward CBP and p300. The pan-inhibitor PU139 triggers caspase-independent cell death in cell culture. Both inhibitors block growth of SK-N-SH neuroblastoma xenografts in mice and the PU139 was shown to synergize with doxorubicin in vivo. The latter also reduces histone lysine acetylation in vivo at concentrations that block neoplastic xenograft growth. This is one of the very few reports on hypoacetylating agents with in vivo anticancer activity.

Emerging drugs for diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most frequent non-Hodgkin lymphoma in western countries. Despite the addition of rituximab to chemotherapy, the prognosis is still poor and almost one-third of patients fail or relapse after first-line treatment. Gene expression profiling has identified three main signatures related to subgroups with different biological characteristics and responses to treatment. Novel agents targeting the oncogenic drivers of these subsets are currently under investigation with the aim of providing a tailored approach and avoiding unnecessary toxicity. Herein, we review the emerging therapies for DLBCL with a focus on preclinical and early clinical trials as well as future directions.

Integrated analysis of cancer-related pathways affected by genetic and epigenetic alterations in gastric cancer

BACKGROUND

The profiles of genetic and epigenetic alterations in cancer-related pathways are considered to be useful for selection of patients likely to respond to specific drugs, including molecular-targeted and epigenetic drugs. In this study, we aimed to characterize such profiles in gastric cancers (GCs).

METHODS

Genetic alterations of 55 cancer-related genes were analyzed by a benchtop next-generation sequencer. DNA methylation statuses were analyzed by a bead array with 485,512 probes.

RESULTS

The WNT pathway was activated by mutations of CTNNB1 in 2 GCs and potentially by aberrant methylation of its negative regulators, such as DKK3, NKD1, and SFRP1, in 49 GCs. The AKT/mTOR pathway was activated by mutations of PIK3CA and PTPN11 in 4 GCs. The MAPK pathway was activated by mutations and gene amplifications of ERBB2, FLT3, and KRAS in 11 GCs. Cell-cycle regulation was affected by aberrant methylation of CDKN2A and CHFR in 13 GCs. Mismatch repair was affected by a mutation of MLH1 in 1 GC and by aberrant methylation of MLH1 in 2 GCs. The p53 pathway was inactivated by mutations of TP53 in 19 GCs and potentially by aberrant methylation of its downstream genes in 38 GCs. Cell adhesion was affected by mutations of CDH1 in 2 GCs.

CONCLUSIONS

Genes involved in cancer-related pathways were more frequently affected by epigenetic alterations than by genetic alterations. The profiles of genetic and epigenetic alterations are expected to be useful for selection of the patients who are likely to benefit from specific drugs.

Epigenetic alterations of the Wnt signaling pathway in cancer: a mini review

Epigenetic mechanisms play a crucial role in cellular proliferation, migration and differentiation in both normal and neoplastic development. One of the key signaling pathways whose components are altered through the epigenetic mechanisms is the Wnt signaling pathway. In this review, we briefly discuss the key concepts of epigenetics and focus on the recent advances in the Wnt signaling pathway research and its potential diagnostic and therapeutic implications.

Cancer-like epigenetic derangements of human pluripotent stem cells and their impact on applications in regeneration and repair

A growing body of work has raised concern that many human pluripotent stem cell (hPSC) lines possess tumorigenic potential following differentiation to clinically relevant lineages. In this review, we highlight recent work characterizing the spectrum of cancer-like epigenetic derangements in human embryonic stem cells (hESC) and human induced pluripotent stem cells (hiPSC) that are associated with reprogramming errors or prolonged culture that may contribute to such tumorigenicity. These aberrations include cancer-like promoter DNA hypermethylation and histone marks associated with pluripotency, as well as aberrant X-chromosome regulation. We also feature recent work that suggests optimized high-fidelity reprogramming derivation methods can minimize cancer-associated epigenetic aberrations in hPSC, and thus ultimately improve the ultimate clinical utility of hiPSC in regenerative medicine.

Modulation of microRNA expression in human lung cancer cells by the G9a histone methyltransferase inhibitor BIX01294

MicroRNAs (miRNAs) are small non-coding RNAs that regulate the expression of their target genes at the post-transcriptional level. In cancer cells, miRNAs, depending on the biological functions of their target genes, may have a tumor-promoting or -suppressing effect. Treatment of cancer cells with inhibitors of DNA methylation and/or histone deacetylation modulates the expression level of miRNAs, which provides evidence for epigenetic regulation of miRNA expression. The consequences of inhibition of histone methyltransferase on miRNA expression, however, have not been thoroughly investigated. The present study examined the expression pattern of miRNAs in the non-small cell lung cancer cell line, H1299 with or without treatment of BIX01294, a potent chemical inhibitor of G9a methyltransferase that catalyzes the mono-and di-methylation of the lysine 9 residue of histone H3. By coupling microarray analysis with quantitative real-time polymerase chain reaction analysis, two miRNAs were identified that showed consistent downregulation following BIX01294 treatment. The results indicate that histone H3 methylation regulates miRNA expression in lung cancer cells, which may provide additional insight for future chemical treatment of lung cancer.

Exploiting epigenetic vulnerabilities for cancer therapeutics

Epigenetic deregulation is a hallmark of cancer, and there has been increasing interest in therapeutics that target chromatin-modifying enzymes and other epigenetic regulators. The rationale for applying epigenetic drugs to treat cancer is twofold. First, epigenetic changes are reversible, and drugs could therefore be used to restore the normal (healthy) epigenetic landscape. However, it is unclear whether drugs can faithfully restore the precancerous epigenetic state. Second, chromatin regulators are often mutated in cancer, making them attractive drug targets. However, in most instances it is unknown whether cancer cells are addicted to these mutated chromatin proteins, or whether their mutation merely results in epigenetic instability conducive to the selection of secondary aberrations. An alternative incentive for targeting chromatin regulators is the exploitation of cancer-specific vulnerabilities, including synthetic lethality, caused by epigenetic deregulation. We review evidence for the hypothesis that mechanisms other than oncogene addiction are a basis for the application of epigenetic drugs, and propose future research directions.

A chromatin modifier genetic screen identifies SIRT2 as a modulator of response to targeted therapies through the regulation of MEK kinase activity

Resistance to targeted therapies is a major problem in cancer treatment. The epidermal growth factor receptor (EGFR) antibody drugs are effective in a subset of colorectal cancers, but the molecular mechanisms of resistance are understood poorly. Genes involved in epigenetic regulation are frequently deregulated in cancer, raising the possibility that such genes also contribute to drug resistance. Using a focused RNA interference library for genes involved in epigenetic regulation, we identify sirtuin2 (SIRT2), an NAD(+)-dependent deacetylase, as a modulator of the response to EGFR inhibitors in colon and lung cancer. SIRT2 loss also conferred resistance to BRAF and MEK inhibitors in BRAF mutant melanoma and KRAS mutant colon cancers, respectively. These results warrant further investigation into the potential role of SIRT2 in resistance to drugs that act in the receptor tyrosine kinase-RAS-RAF-MEK-ERK signaling pathway.

The histone demethylase KDM3A is a microRNA-22-regulated tumor promoter in Ewing Sarcoma

Ewing Sarcoma is a biologically aggressive bone and soft tissue malignancy affecting children and young adults. Ewing Sarcoma pathogenesis is driven by EWS/Ets fusion oncoproteins, of which EWS/Fli1 is the most common. We have previously shown that microRNAs (miRs) regulated by EWS/Fli1 contribute to the pro-oncogenic program in Ewing Sarcoma. Here we show that miR-22, an EWS/Fli1-repressed miR, is inhibitory to Ewing Sarcoma clonogenic and anchorage-independent cell growth, even at modest overexpression levels. Our studies further identify the H3K9me1/2 histone demethylase KDM3A (JMJD1A/JHDM2A) as a new miR-22-regulated gene. We show that KDM3A is overexpressed in Ewing Sarcoma, and that its depletion inhibits clonogenic and anchorage-independent growth in multiple patient-derived cell lines, and tumorigenesis in a xenograft model. KDM3A depletion further results in augmentation of the levels of the repressive H3K9me2 histone mark, and downregulation of pro-oncogenic factors in Ewing Sarcoma. Together, our studies identify the histone demethylase KDM3A as a new, miR-regulated, tumor promoter in Ewing Sarcoma.

Targeting the epigenome in lung cancer: expanding approaches to epigenetic therapy

Epigenetic aberrations offer dynamic and reversible targets for cancer therapy; increasingly, alteration via overexpression, mutation, or rearrangement is found in genes that control the epigenome. Such alterations suggest a fundamental role in carcinogenesis. Here, we consider three epigenetic mechanisms: DNA methylation, histone tail modification and non-coding, microRNA regulation. Evidence for each of these in lung cancer origin or progression has been gathered, along with evidence that epigenetic alterations might be useful in early detection. DNA hypermethylation of tumor suppressor promoters has been observed, along with global hypomethylation and hypoacetylation, suggesting an important role for tumor suppressor gene silencing. These features have been linked as prognostic markers with poor outcome in lung cancer. Several lines of evidence have also suggested a role for miRNA in carcinogenesis and in outcome. Cigarette smoke downregulates miR-487b, which targets both RAS and MYC; RAS is also a target of miR-let-7, again downregulated in lung cancer. Together the evidence implicates epigenetic aberration in lung cancer and suggests that targeting these aberrations should be carefully explored. To date, DNA methyltransferase and histone deacetylase inhibitors have had minimal clinical activity. Explanations include the possibility that the agents are not sufficiently potent to invoke epigenetic reversion to a more normal state; that insufficient time elapses in most clinical trials to observe true epigenetic reversion; and that doses often used may provoke off-target effects such as DNA damage that prevent epigenetic reversion. Combinations of epigenetic therapies may address those problems. When epigenetic agents are used in combination with chemotherapy or targeted therapy it is hoped that downstream biological effects will provoke synergistic cytotoxicity. This review evaluates the challenges of exploiting the epigenome in the treatment of lung cancer.

Structural basis for the inhibition of histone deacetylase 8 (HDAC8), a key epigenetic player in the blood fluke Schistosoma mansoni

The treatment of schistosomiasis, a disease caused by blood flukes parasites of the Schistosoma genus, depends on the intensive use of a single drug, praziquantel, which increases the likelihood of the development of drug-resistant parasite strains and renders the search for new drugs a strategic priority. Currently, inhibitors of human epigenetic enzymes are actively investigated as novel anti-cancer drugs and have the potential to be used as new anti-parasitic agents. Here, we report that Schistosoma mansoni histone deacetylase 8 (smHDAC8), the most expressed class I HDAC isotype in this organism, is a functional acetyl-L-lysine deacetylase that plays an important role in parasite infectivity. The crystal structure of smHDAC8 shows that this enzyme adopts a canonical α/β HDAC fold, with specific solvent exposed loops corresponding to insertions in the schistosome HDAC8 sequence. Importantly, structures of smHDAC8 in complex with generic HDAC inhibitors revealed specific structural changes in the smHDAC8 active site that cannot be accommodated by human HDACs. Using a structure-based approach, we identified several small-molecule inhibitors that build on these specificities. These molecules exhibit an inhibitory effect on smHDAC8 but show reduced affinity for human HDACs. Crucially, we show that a newly identified smHDAC8 inhibitor has the capacity to induce apoptosis and mortality in schistosomes. Taken together, our biological and structural findings define the framework for the rational design of small-molecule inhibitors specifically interfering with schistosome epigenetic mechanisms, and further support an anti-parasitic epigenome targeting strategy to treat neglected diseases caused by eukaryotic pathogens.

Schistosomiasis, a neglected parasitic disease caused by flatworms of the genus Schistosoma, is responsible for hundreds of thousands of deaths yearly. Its treatment currently depends on a single drug, praziquantel, with reports of drug-resistant parasites. Human epigenetic enzymes, in particular histone deacetylases (HDACs), are predominantly attractive inhibitory targets for anti-cancer therapies. Validated scaffolds against these enzymes could also be used as leads in the search for novel specific drugs against schistosomiasis. In our study, we show that Schistosoma mansoni histone deacetylase 8 (smHDAC8) is a functional acetyl-L-lysine deacetylase that plays an important role in parasite infectivity and is therefore a relevant target for drug discovery. The determination of the atomic structures of smHDAC8 in complex with generic HDAC inhibitors revealed that the architecture of the smHDAC8 active site pocket differed significantly from its human counterparts and provided a framework for the development of inhibitors selectively interfering with schistosome epigenetic mechanisms. In agreement, this information enabled us to identify several small-molecule scaffolds that possess specific inhibitory effects on smHDAC8 and cause mortality in schistosomes. Our results provide the proof of concept that targeting epigenetic enzymes is a valid approach to treat neglected diseases caused by eukaryotic pathogens.

RGS6 suppresses Ras-induced cellular transformation by facilitating Tip60-mediated Dnmt1 degradation and promoting apoptosis

The RAS protooncogene has a central role in regulation of cell proliferation, and point mutations leading to oncogenic activation of Ras occur in a large number of human cancers. Silencing of tumor-suppressor genes by DNA methyltransferase 1 (Dnmt1) is essential for oncogenic cellular transformation by Ras, and Dnmt1 is overexpressed in numerous human cancers. Here we provide new evidence that the pleiotropic regulator of G protein signaling (RGS) family member RGS6 suppresses Ras-induced cellular transformation by facilitating Tip60-mediated degradation of Dmnt1 and promoting apoptosis. Employing mouse embryonic fibroblasts from wild-type and RGS6(-/-) mice, we found that oncogenic Ras induced upregulation of RGS6, which in turn blocked Ras-induced cellular transformation. RGS6 functions to suppress cellular transformation in response to oncogenic Ras by downregulating Dnmt1 protein expression leading to inhibition of Dnmt1-mediated anti-apoptotic activity. Further experiments showed that RGS6 functions as a scaffolding protein for both Dnmt1 and Tip60 and is required for Tip60-mediated acetylation of Dnmt1 and subsequent Dnmt1 ubiquitylation and degradation. The RGS domain of RGS6, known only for its GTPase-activating protein activity toward Gα subunits, was sufficient to mediate Tip60 association with RGS6. This work demonstrates a novel signaling action for RGS6 in negative regulation of oncogene-induced transformation and provides new insights into our understanding of the mechanisms underlying Ras-induced oncogenic transformation and regulation of Dnmt1 expression. Importantly, these findings identify RGS6 as an essential cellular defender against oncogenic stress and a potential therapeutic target for developing new cancer treatments.

Selective inhibition of tumor oncogenes by disruption of super-enhancers

Chromatin regulators have become attractive targets for cancer therapy, but it is unclear why inhibition of these ubiquitous regulators should have gene-specific effects in tumor cells. Here, we investigate how inhibition of the widely expressed transcriptional coactivator BRD4 leads to selective inhibition of the MYC oncogene in multiple myeloma (MM). BRD4 and Mediator were found to co-occupy thousands of enhancers associated with active genes. They also co-occupied a small set of exceptionally large super-enhancers associated with genes that feature prominently in MM biology, including the MYC oncogene. Treatment of MM tumor cells with the BET-bromodomain inhibitor JQ1 led to preferential loss of BRD4 at super-enhancers and consequent transcription elongation defects that preferentially impacted genes with super-enhancers, including MYC. Super-enhancers were found at key oncogenic drivers in many other tumor cells. These observations have implications for the discovery of cancer therapeutics directed at components of super-enhancers in diverse tumor types.

Cancer epigenetics: new therapies and new challenges

Cancer is nowadays considered to be both a genetic and an epigenetic disease. The most well studied epigenetic modification in humans is DNA methylation; however it becomes increasingly acknowledged that DNA methylation does not work alone, but rather is linked to other modifications, such as histone modifications. Epigenetic abnormalities are reversible and as a result novel therapies that work by reversing epigenetic effects are being increasingly explored. The biggest clinical impact of epigenetic modifying agents in neoplastic disorders thus far has been in haematological malignancies, and the efficacy of DNMT inhibitors and HDAC inhibitors in blood cancers clearly attests to the principle that therapeutic modification of the cancer cell epigenome can produce clinical benefit. This paper will discuss the most well studied epigenetic modifications and how these are linked to cancer, will give a brief overview of the clinical use of epigenetics as biomarkers, and will focus in more detail on epigenetic drugs and their use in solid and blood cancers.