Epi-drugs to fight cancer: from chemistry to cancer treatment, the road ahead. Int J Biochem Cell Biol. 2009;41:199-213. [PMID: 18790076 DOI: 10.1016/j.biocel.2008.08.020]

Targeting the epigenome with advanced delivery strategies for epigenetic modulators

Epigenetics mechanisms play a significant role in human diseases by altering DNA methylation status, chromatin structure, and/or modifying histone proteins. By modulating the epigenetic status, the expression of genes can be regulated without any change in the DNA sequence itself. Epigenetic drugs exhibit promising therapeutic efficacy against several epigenetically originated diseases including several cancers, neurodegenerative diseases, metabolic disorders, cardiovascular disorders, and so forth. Currently, a considerable amount of research is focused on discovering new drug molecules to combat the existing research gap in epigenetic drug therapy. A novel and efficient delivery system can be established as a promising approach to overcome the drawbacks associated with the current epigenetic modulators. Therefore, formulating the existing epigenetic drugs with distinct encapsulation strategies in nanocarriers, including solid lipid nanoparticles, nanogels, bio-engineered nanocarriers, liposomes, surface modified nanoparticles, and polymer-drug conjugates have been examined for therapeutic efficacy. Nonetheless, several epigenetic modulators are untouched for their therapeutic potential through different delivery strategies. This review provides a comprehensive up to date discussion on the research findings of various epigenetics mechanism, epigenetic modulators, and delivery strategies utilized to improve their therapeutic outcome. Furthermore, this review also highlights the recently emerged CRISPR tool for epigenome editing.

Repurposing Plant-Based Histone Acetyltransferase Inhibitors: A Review of Novel Therapeutic Strategies Against Drug-Resistant Fungal Biofilms

The rapid emergence of drug-resistant fungal strains necessitates the development of novel therapeutic approaches for battling biofilm-related infections. Biofilms, efflux pumps, and suppression of virulence traits in pathogenic yeasts are governed by epigenetic enzymes, namely, histone acetyltransferases (HATs) and histone deacetylases (HDACs). The review article is focused on the use of histone acetyltransferase inhibitors (HATi), a mechanism-based epidrug that inactivates the regular function of HATs. With an emphasis on specific plant-based HATi and their Structure-Activity Relationship (SAR), the review enumerates the extensive list of anticancer HATi that can be screened for antifungal activities. By repurposing these anticancer HATi, this approach may help generate broad-spectrum antifungal medications that highlight common biological pathways between fungus and cancer, possibly revolutionizing both treatment domains.

Pterostilbene Reverses Epigenetic Silencing of Nrf2 and Enhances Antioxidant Response in Endothelial Cells in Hyperglycemic Microenvironment

The epigenetic regulation of nuclear factor erythroid 2-related factor 2 (Nrf2), a pivotal redox transcription factor, plays a crucial role in maintaining cellular homeostasis. Recent research has underscored the significance of epigenetic modifications of Nrf2 in the pathogenesis of diabetic foot ulcers (DFUs). This study investigates the epigenetic reversal of Nrf2 by pterostilbene (PTS) in human endothelial cells in a hyperglycemic microenvironment (HGM). The activation potential of PTS on Nrf2 was evaluated through ARE-Luciferase reporter assays and nuclear translocation studies. Following 72 h of exposure to an HGM, mRNA expression and protein levels of Nrf2 and its downstream targets NAD(P)H quinone oxidoreductase 1 (NQO1), heme-oxygenase 1(HO-1), superoxide dismutase (SOD), and catalase (CAT) exhibited a decrease, which was mitigated in PTS-pretreated endothelial cells. Epigenetic markers, including histone deacetylases (HDACs class I-IV) and DNA methyltransferases (DNMTs 1/3A and 3B), were found to be downregulated under diabetic conditions. Specifically, Nrf2-associated HDACs, including HDAC1, HDAC2, HDAC3, and HDAC4, were upregulated in HGM-induced endothelial cells. This upregulation was reversed in PTS-pretreated cells, except for HDAC2, which exhibited elevated expression in endothelial cells treated with PTS in a hyperglycemic microenvironment. Additionally, PTS was observed to reverse the activity of the methyltransferase enzyme DNMT. Furthermore, CpG islands in the Nrf2 promoter were hypermethylated in cells exposed to an HGM, a phenomenon potentially counteracted by PTS pretreatment, as shown by methyl-sensitive restriction enzyme PCR (MSRE-qPCR) analysis. Collectively, our findings highlight the ability of PTS to epigenetically regulate Nrf2 expression under hyperglycemic conditions, suggesting its therapeutic potential in managing diabetic complications.

Regulation of T cells in the tumor microenvironment by histone methylation: LSD1 inhibition-a new direction for enhancing immunotherapy

Although immune checkpoint blockade (ICB) has been shown to achieve durable therapeutic responses in various types of tumors, only 20-40 % of patients benefit from this therapy. A growing body of research suggests that epigenetic modulation of the tumor microenvironment may be a promising direction for enhancing the efficacy of immunotherapy, for example, histone methylation plays an important role in the regulation of T cells in the tumor microenvironment (TME). In particular, histone lysine-specific demethylase 1 (LSD1/KDM1A), as an important histone-modifying enzyme in epigenetics, was found to be an important factor in the regulation of T cells. Therefore, this paper will summarize the effects of histone methylation, especially LSD1, on T cells in the TME to enhance the efficacy of anti-PD-1 immunotherapy. To provide a strong theoretical basis for the strategy of combining LSD1 inhibitors with anti-PD-1/PD-L1 immunotherapy, thus adding new possibilities to improve the survival of tumor patients.

Dietary Polyphenols Remodel DNA Methylation Patterns of NRF2 in Chronic Disease

The nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor crucial in regulating cellular homeostasis and apoptosis. The NRF2 gene has been implicated in various biological activities, including antioxidant, anti-inflammatory, and anticancer properties. NRF2 can be regulated genetically and epigenetically at the transcriptional, post-transcriptional, and translational levels. Although DNA methylation is one of the critical biological processes vital for gene expression, sometimes, anomalous methylation patterns result in the dysregulation of genes and consequent diseases and disorders. Several studies have reported promoter hypermethylation downregulated NRF2 expression and its downstream targets. In contrast to the unalterable nature of genetic patterns, epigenetic changes can be reversed, opening up new possibilities in developing therapies for various metabolic disorders and diseases. This review discusses the current state of the NRF2-mediated antioxidative and chemopreventive activities of several natural phytochemicals, including sulforaphane, resveratrol, curcumin, luteolin, corosolic acid, apigenin, and most other compounds that have been found to activate NRF2. This epigenetic reversal of hypermethylated NRF2 states provides new opportunities for research into dietary phytochemistry that affects the human epigenome and the possibility for cutting-edge approaches to target NRF2-mediated signaling to prevent chronic disorders.

Epigenetic targets in B- and T-cell lymphomas: latest developments

Non-Hodgkin's lymphomas (NHLs) comprise a diverse group of diseases, either of mature B-cell or of T-cell derivation, characterized by heterogeneous molecular features and clinical manifestations. While most of the patients are responsive to standard chemotherapy, immunotherapy, radiation and/or stem cell transplantation, relapsed and/or refractory cases still have a dismal outcome. Deep sequencing analysis have pointed out that epigenetic dysregulations, including mutations in epigenetic enzymes, such as chromatin modifiers and DNA methyltransferases (DNMTs), are prevalent in both B- cell and T-cell lymphomas. Accordingly, over the past decade, a large number of epigenetic-modifying agents have been developed and introduced into the clinical management of these entities, and a few specific inhibitors have already been approved for clinical use. Here we summarize the main epigenetic alterations described in B- and T-NHL, that further supported the clinical development of a selected set of epidrugs in determined diseases, including inhibitors of DNMTs, histone deacetylases (HDACs), and extra-terminal domain proteins (bromodomain and extra-terminal motif; BETs). Finally, we highlight the most promising future directions of research in this area, explaining how bioinformatics approaches can help to identify new epigenetic targets in B- and T-cell lymphoid neoplasms.

Epigenetic citizenship and political claims-making: the ethics of molecularizing structural racism

Epigenetics has generated excitement over its potential to inform health disparities research by capturing the molecular signatures of social experiences. This paper highlights the concerns implied by these expectations of epigenetics research and discusses the possible ramifications of 'molecularizing' the forms of social suffering currently examined in epigenetics studies. Researchers working with oppressed populations-particularly racially marginalized groups-should further anticipate how their results might be interpreted to avoid fueling prejudiced claims of biological essentialism. Introducing the concept of 'epigenetic citizenship,' this paper considers the ways environmentally responsive methylation cues may be used in direct-to-consumer testing, healthcare, and biopolitical interactions. The conclusion addresses the future of social epigenetics research and the utility of an epigenetic citizenship framework.

DNA Methylation Biomarkers for Prediction of Response to Platinum-Based Chemotherapy: Where Do We Stand?

Simple Summary

Platinum-based agents are one of the most widely used chemotherapy drugs for various types of cancer. However, one of the main challenges in the application of platinum drugs is resistance, which is currently being widely investigated. Epigenetic DNA methylation-based biomarkers are promising to aid in the selection of patients, helping to foresee their platinum therapy response in advance. These biomarkers enable minimally invasive patient sample collection, short analysis, and good sensitivity. Hence, improved methodologies for the detection and quantification of DNA methylation biomarkers will facilitate their use in the choice of an optimal treatment strategy.

Abstract

Platinum-based chemotherapy is routinely used for the treatment of several cancers. Despite all the advances made in cancer research regarding this therapy and its mechanisms of action, tumor resistance remains a major concern, limiting its effectiveness. DNA methylation-based biomarkers may assist in the selection of patients that may benefit (or not) from this type of treatment and provide new targets to circumvent platinum chemoresistance, namely, through demethylating agents. We performed a systematic search of studies on biomarkers that might be predictive of platinum-based chemotherapy resistance, including in vitro and in vivo pre-clinical models and clinical studies using patient samples. DNA methylation biomarkers predictive of response to platinum remain mostly unexplored but seem promising in assisting clinicians in the generation of more personalized follow-up and treatment strategies. Improved methodologies for their detection and quantification, including non-invasively in liquid biopsies, are additional attractive features that can bring these biomarkers into clinical practice, fostering precision medicine.

A large scale mass spectrometry-based histone screening for assessing epigenetic developmental toxicity

Toxicoepigenetics is an emerging field that studies the toxicological impact of compounds on protein expression through heritable, non-genetic mechanisms, such as histone post-translational modifications (hPTMs). Due to substantial progress in the large-scale study of hPTMs, integration into the field of toxicology is promising and offers the opportunity to gain novel insights into toxicological phenomena. Moreover, there is a growing demand for high-throughput human-based in vitro assays for toxicity testing, especially for developmental toxicity. Consequently, we developed a mass spectrometry-based proof-of-concept to assess a histone code screening assay capable of simultaneously detecting multiple hPTM-changes in human embryonic stem cells. We first validated the untargeted workflow with valproic acid (VPA), a histone deacetylase inhibitor. These results demonstrate the capability of mapping the hPTM-dynamics, with a general increase in acetylations as an internal control. To illustrate the scalability, a dose–response study was performed on a proof-of-concept library of ten compounds (1) with a known effect on the hPTMs (BIX-01294, 3-Deazaneplanocin A, Trichostatin A, and VPA), (2) classified as highly embryotoxic by the European Centre for the Validation of Alternative Methods (ECVAM) (Methotrexate, and All-trans retinoic acid), (3) classified as non-embryotoxic by ECVAM (Penicillin G), and (4) compounds of abuse with a presumed developmental toxicity (ethanol, caffeine, and nicotine).

Epigenetic modulation of antitumor immunity for improved cancer immunotherapy

Epigenetic mechanisms play vital roles not only in cancer initiation and progression, but also in the activation, differentiation and effector function(s) of immune cells. In this review, we summarize current literature related to epigenomic dynamics in immune cells impacting immune cell fate and functionality, and the immunogenicity of cancer cells. Some important immune-associated genes, such as granzyme B, IFN-γ, IL-2, IL-12, FoxP3 and STING, are regulated via epigenetic mechanisms in immune or/and cancer cells, as are immune checkpoint molecules (PD-1, CTLA-4, TIM-3, LAG-3, TIGIT) expressed by immune cells and tumor-associated stromal cells. Thus, therapeutic strategies implementing epigenetic modulating drugs are expected to significantly impact the tumor microenvironment (TME) by promoting transcriptional and metabolic reprogramming in local immune cell populations, resulting in inhibition of immunosuppressive cells (MDSCs and Treg) and the activation of anti-tumor T effector cells, professional antigen presenting cells (APC), as well as cancer cells which can serve as non-professional APC. In the latter instance, epigenetic modulating agents may coordinately promote tumor immunogenicity by inducing de novo expression of transcriptionally repressed tumor-associated antigens, increasing expression of neoantigens and MHC processing/presentation machinery, and activating tumor immunogenic cell death (ICD). ICD provides a rich source of immunogens for anti-tumor T cell cross-priming and sensitizing cancer cells to interventional immunotherapy. In this way, epigenetic modulators may be envisioned as effective components in combination immunotherapy approaches capable of mediating superior therapeutic efficacy.

DNA methylation in stress and depression: from biomarker to therapeutics

Epigenetic mechanisms such as DNA methylation (DNAm) have been associated with stress responses and increased vulnerability to depression. Abnormal DNAm is observed in stressed animals and depressed individuals. Antidepressant treatment modulates DNAm levels and regulates gene expression in diverse tissues, including the brain and the blood. Therefore, DNAm could be a potential therapeutic target in depression. Here, we reviewed the current knowledge about the involvement of DNAm in the behavioural and molecular changes associated with stress exposure and depression. We also evaluated the possible use of DNAm changes as biomarkers of depression. Finally, we discussed current knowledge limitations and future perspectives.

Epigenetic linkage of systemic lupus erythematosus and nutrition

The term "epigenetics" refers to a series of meiotically/mitotically inheritable alterations in gene expression, related to environmental factors, without disruption on DNA sequences of bases. Recently, the pathophysiology of autoimmune diseases (ADs) has been closely linked to epigenetic modifications. Actually, epigenetic mechanisms can modulate gene expression or repression of targeted cells and tissues involved in autoimmune/inflammatory conditions acting as keys effectors in regulation of adaptive and innate responses. ADs, as systemic lupus erythematosus (SLE), a rare disease that still lacks effective treatment, is characterized by epigenetic marks in affected cells.Taking into account that epigenetic mechanisms have been proposed as a winning strategy in the search of new more specific and personalized therapeutics agents. Thus, pharmacology and pharmacoepigenetic studies about epigenetic regulations of ADs may provide novel individualized therapies. Focussing in possible implicated factors on development and predisposition of SLE, diet is feasibly one of the most important factors since it is linked directly to epigenetic alterations and these epigenetic changes may augment or diminish the risk of SLE. Nevertheless, several studies have guaranteed that dietary therapy could be a promise to SLE patients via prophylactic actions deprived of side effects of pharmacology, decreasing co-morbidities and improving lifestyle of SLE sufferers.Herein, we review and discuss the cross-link between epigenetic mechanisms on SLE predisposition and development, as well as the influence of dietary factors on regulation epigenetic modifications that would eventually make a positive impact on SLE patients.

Bioinformatic tools for DNA methylation and histone modification: A survey

Epigenetic inheritance occurs due to different mechanisms such as chromatin and histone modifications, DNA methylation and processes mediated by non-coding RNAs. It leads to changes in gene expressions and the emergence of new traits in different organisms in many diseases such as cancer. Recent advances in experimental methods led to the identification of epigenetic target sites in various organisms. Computational approaches have enabled us to analyze mass data produced by these methods. Next-generation sequencing (NGS) methods have been broadly used to identify these target sites and their patterns. By using these patterns, the emergence of diseases could be prognosticated. In this study, target site prediction tools for two major epigenetic mechanisms comprising histone modification and DNA methylation are reviewed. Publicly accessible databases are reviewed as well. Some suggestions regarding the state-of-the-art methods and databases have been made, including examining patterns of epigenetic changes that are important in epigenotypes detection.

Epidrug Repurposing: Discovering New Faces of Old Acquaintances in Cancer Therapy

Gene mutations are strongly associated with tumor progression and are well known in cancer development. However, recently discovered epigenetic alterations have shown the potential to greatly influence tumoral response to therapy regimens. Such epigenetic alterations have proven to be dynamic, and thus could be restored. Due to their reversible nature, the promising opportunity to improve chemotherapy response using epigenetic therapy has arisen. Beyond helping to understand the biology of the disease, the use of modern clinical epigenetics is being incorporated into the management of the cancer patient. Potential epidrug candidates can be found through a process known as drug repositioning or repurposing, a promising strategy for the discovery of novel potential targets in already approved drugs. At present, novel epidrug candidates have been identified in preclinical studies and some others are currently being tested in clinical trials, ready to be repositioned. This epidrug repurposing could circumvent the classic paradigm where the main focus is the development of agents with one indication only, while giving patients lower cost therapies and a novel precision medical approach to optimize treatment efficacy and reduce toxicity. This review focuses on the main approved epidrugs, and their druggable targets, that are currently being used in cancer therapy. Also, we highlight the importance of epidrug repurposing by the rediscovery of known chemical entities that may enhance epigenetic therapy in cancer, contributing to the development of precision medicine in oncology.

New Insights into Mechanisms of Endocrine-Disrupting Chemicals in Thyroid Diseases: The Epigenetic Way

In recent years, the presence in the environment of chemical compounds with thyroid-disrupting effects is progressively increased. This phenomenon has risen concern for human health as the preservation of thyroid system homeostasis is essential for fetal development and for maintaining psychological and physiological wellbeing. An increasing number of studies explored the role of different classes of toxicants in the occurrence and severity of thyroid diseases, but large epidemiological studies are limited and only a few animal or in vitro studies have attempted to identify the mechanisms of chemical action. Recently, epigenetic changes such as alteration of methylation status or modification of non-coding RNAs have been suggested as correlated to possible deleterious effects leading to different thyroid disorders in susceptible individuals. This review aims to analyze the epigenetic alterations putatively induced by chemical exposures and involved in the onset of frequent thyroid diseases such as thyroid cancer, autoimmune thyroiditis and disruption of fetal thyroid homeostasis.

Cancer Treatment: An Epigenetic View

Cancer can be identified as an uncontrolled growth and reproduction of cell. Accumulation of genetic aberrations (mutations of oncogenes and tumor-suppressor genes and epigenetic modifications) is one of the characteristics of cancer cell. Increasing number of studies highlighted importance of the epigenetic alterations in cancer treatment and prognosis. Now, cancer epigenetics have a huge importance for developing novel biomarkers and therapeutic target for cancer. In this review, we will provide a summary of the major epigenetic changes involved in cancer and preclinical results of epigenetic therapeutics.

Roles of Histone Deacetylases and Inhibitors in Anticancer Therapy

Histones are the main structural proteins of eukaryotic chromatin. Histone acetylation/ deacetylation are the epigenetic mechanisms of the regulation of gene expression and are catalyzed by histone acetyltransferases (HAT) and histone deacetylases (HDAC). These epigenetic alterations of DNA structure influence the action of transcription factors which can induce or repress gene transcription. The HATs catalyze acetylation and the events related to gene transcription and are also responsible for transporting newly synthesized histones from the cytoplasm to the nucleus. The activity of HDACs is mainly involved in silencing gene expression and according to their specialized functions are divided into classes I, II, III and IV. The disturbance of the expression and mutations of HDAC genes causes the aberrant transcription of key genes regulating important cancer pathways such as cell proliferation, cell-cycle regulation and apoptosis. In view of their role in cancer pathways, HDACs are considered promising therapeutic targets and the development of HDAC inhibitors is a hot topic in the search for new anticancer drugs. The present review will focus on HDACs I, II and IV, the best known inhibitors and potential alternative inhibitors derived from natural and synthetic products which can be used to influence HDAC activity and the development of new cancer therapies.

Demethylation of miR-195 suppresses prostate cancer cell proliferation, migration and invasion

Prostate cancer (PCa) is the most prevalent cancer among men and the second leading cause of tumor-associated deaths worldwide, with increasing incidence rates over the last 10 years. Recently, miR-195 was reported to be hypermethylated at its promoter CpG island and down-regulated in hepatocellular carcinoma. However, the function of miR-195 and the underlying mechanisms in PCa remain unknown. Here, we report that a significant down-regulation of microRNA-195 (miR-195) in PCa tissues and cell lines was associated with promoter methylation status. Overexpression of miR-195 significantly suppressed cell proliferation, migration, invasion and epithelial-mesenchymal transition (increased E-cadherin and decreased N-cadherin) in PCa cells. We further demonstrated that transfection with a miR-195 inhibitor reversed the inhibitory effect of the DNA methyltransferase inhibitor 5-azacytidine on the proliferation, migration and invasion ability of PCa cells. In summary, our findings suggest that miR-195 may function as a crucial tumor suppressor in PCa.

BET inhibition therapy counteracts cancer cell survival, clonogenic potential and radioresistance mechanisms in rhabdomyosarcoma cells

The antitumour effects of OTX015, a first-in-class BET inhibitor (BETi), were investigated as a single agent or in combination with ionizing radiation (IR) in preclinical in vitro models of rhabdomyosarcoma (RMS), the most common childhood soft tissue sarcoma. Herein, we demonstrated the upregulation of BET Bromodomain gene expression in RMS tumour biopsies and cell lines compared to normal skeletal muscle. In vitro experiments showed that OTX015 significantly reduced RMS cell proliferation by altering cell cycle modulators and apoptotic related proteins due to the accumulation of DNA breaks that cells are unable to repair. Interestingly, OTX015 also impaired migration capacity and tumour-sphere architecture by downregulating pro-stemness genes and was able to potentiate ionizing radiation effects by reducing the expression of different drivers of tumour dissemination and resistance mechanisms, including the GNL3 gene, that we correlated for the first time with the RMS phenotype. In conclusion, our research sheds further light on the molecular events of OTX015 action against RMS cells and indicates this novel BETi as an effective option to improve therapeutic strategies and overcome the development of resistant cancer cells in patients with RMS.

Enzymatic and Biological Characterization of Novel Sirtuin Modulators against Cancer

Sirtuins, a family of nicotinamide adenine dinucleotide (NAD⁺)-dependent lysine deacetylases, are promising targets for anticancer treatment. Recently, we characterized a novel pan-sirtuin (SIRT) inhibitor, MC2494, displaying antiproliferative effects and able to induce death pathways in several human cancer cell lines and decrease tumor growth in vivo. Based on the chemical scaffold of MC2494, and by applying a structure–activity relationship approach, we developed a small library of derivative compounds and extensively analyzed their enzymatic action at cellular level as well as their ability to induce cell death. We also investigated the effect of MC2494 on regulation of cell cycle progression in different cancer cell lines. Our investigations indicated that chemical substitutions applied to MC2494 scaffold did not confer higher efficacy in terms of biological activity and SIRT1 inhibition, but carbethoxy-containing derivatives showed higher SIRT2 specificity. The carbethoxy derivative of MC2494 and its 2-methyl analog displayed the strongest enzymatic activity. Applied chemical modifications improved the enzymatic selectivity of these SIRT inhibitors. Additionally, the observed activity of MC2494 via cell cycle and apoptotic regulation and inhibition of cell migration supports the potential role of SIRTs as targets in tumorigenesis and makes SIRT-targeting molecules good candidates for novel pharmacological approaches in personalized medicine.

Markers as mediators: A review and synthesis of epigenetics literature

Epigenetics, the study of the processes that control gene expression without a change in DNA sequence, highlights the importance of environmental factors in gene regulation. This paper maps the terrain of epigenetics and identifies four main research subfields: gene expression; molecular epigenetics; clinical epigenetics and epigenetic epidemiology. Within and across these fields, we analyse of what is conceptualised as environment and demonstrate the variable ways authors understand epigenetics environments. Then, following an analysis of the discursive strategies employed by epigenetics researchers, we demonstrate how authors portray the interactions between genes, epigenetics, and environment as relationships linking the outside (where the environment is located) with the inside (where the genes are located). We argue that authors assign specific roles to each actor: the environment as the active player initiating the relationship, the genes as recipients, and epigenetics as mediators between environment and genes. Framed as mediators, epigenetic markers can be understood as enablers of communication between environment and genome, capable of processing and organising signals so as to regulate the interactions between the actors of epigenetic relationships. This finding complicates the observation by social science scholars that the interactions between environment and genes can be understood through the concept of signal.

MicroRNA-596 acts as a tumor suppressor in gastric cancer and is upregulated by promotor demethylation

BACKGROUND

In the present study, we investigated a suppressive role of microRNA-596 (miR-596) in gastric cancer (GC). Moreover, the downregulation of miR-596 in GC cell lines was associated with an increase of miR-596 promoter methylation. We also established that miR-596 controls the expression of peroxiredoxin 1 (PRDX1), which has never been reported before, suggesting that this interaction could play an important role in GC progression.

AIM

To study the potential role and possible regulatory mechanism of miR-596 in GC.

METHODS

The expression levels of miR-596 and PRDX1 in gastric cancer tissues and cell lines were detected by quantitative real-time PCR (qRT-PCR). Western blot and luciferase reporter assay were used to detect the effect of miR-596 on PRDX1 expression. Then, the proliferation, metastasis, and invasion of GC cell lines transfected with miR-596 mimics were analyzed, respectively, by Cell Counting Kit-8 proliferation assay, wound healing assay, and transwell invasion assay. Meanwhile, the methylation status of the promoter CpG islands of miR-596 in GC cell lines was detected by methylation-specific PCR (MSP).

RESULTS

Expression of miR-596 was decreased and PRDX1 was upregulated in GC tissues and cell lines. Overexpression of miR-596 decreased the expression of PRDX1 and luciferase reporter assays detected the direct binding of miR-596 to the 3'-untranslated region (UTR) of PRDX1 transcripts. Furthermore, we found that overexpression of miR-596 remarkably suppressed cell proliferation, migration, and invasion in GC cells. We further analyzed miR-596 promoter methylation by MSP and qRT-PCR, and found the downregulation of miR-596 was associated with promoter methylation status in GC cell lines. Moreover, DNA demethylation and reactivation of miR-596 after treatment with 5-Aza-2’-deoxycytidine inhibited the proliferative ability of GC cells.

CONCLUSION

MiR-596 has a tumor suppressive role in GC and is downregulated partly due to promoter hypermethylation. Furthermore, PRDX1 is one of the putative target genes of miR-596.

Histone Deacetylase Inhibitors: A Prospect in Drug Discovery

Cancer is a provocative issue across the globe and treatment of uncontrolled cell growth follows a deep investigation in the field of drug discovery. Therefore, there is a crucial requirement for discovering an ingenious medicinally active agent that can amend idle drug targets. Increasing pragmatic evidence implies that histone deacetylases (HDACs) are trapped during cancer progression, which increases deacetylation and triggers changes in malignancy. They provide a ground-breaking scaffold and an attainable key for investigating chemical entity pertinent to HDAC biology as a therapeutic target in the drug discovery context. Due to gene expression, an impending requirement to prudently transfer cytotoxicity to cancerous cells, HDAC inhibitors may be developed as anticancer agents. The present review focuses on the basics of HDAC enzymes, their inhibitors, and therapeutic outcomes.

Overexpression of DNA (Cytosine-5)-Methyltransferase 1 (DNMT1) And DNA (Cytosine-5)-Methyltransferase 3A (DNMT3A) Is Associated with Aggressive Behavior and Hypermethylation of Tumor Suppressor Genes in Human Pituitary Adenomas

Background

Alteration of DNA methylation of tumor suppressor genes (TSGs) is one of the most consistent epigenetic changes in human cancers. DNMTs play several important roles in DNA methylation and development of cancers. Regarding DNMTs protein expressions, little is known about the clinical significance and correlation with promoter methylation status of TSGs in human pituitary adenomas.

Material/Methods

We analyzed the protein expression of 3 DNMTs using immunohistochemistry and assessed DNA hypermethylation of RASSF1A, CDH13, CDH1, and CDKN2A (p16) in 63 pituitary adenomas. We examined associations between DNMTs expression and clinicopathological features or promoter methylation status of TSGs.

Results

Overexpression of DNMTs was detected in pituitary adenomas. Frequencies of DNMT1 overexpression were significantly higher in macroadenomas, invasive tumors, and grade III and IV tumors. DNMT3A was frequently detected in invasive tumors and grade IV tumors. In addition, DNMT1 and DNMT3A were frequently detected in high-methylation tumors. Furthermore, in multivariate logistic regression, the significant association between DNMT1 or DNMT3A and high-methylation status persisted after adjusting for clinicopathological features.

Conclusions

Our findings suggested that tumor overexpression of DNMT1 and DNMT3A is associated with tumor aggressive behavior and high-methylation status in pituitary adenomas. Our data support a possible role of DNMT1 and DNMT3A in TSG promoter methylation leading to pituitary adenoma invasion and suggest that inhibition of DNMTs has the potential to become a new therapeutic approach for invasive pituitary adenoma.

Clinically Applicable Inhibitors Impacting Genome Stability

Advances in technology have facilitated the molecular profiling (genomic and transcriptomic) of tumours, and has led to improved stratification of patients and the individualisation of treatment regimes. To fully realize the potential of truly personalised treatment options, we need targeted therapies that precisely disrupt the compensatory pathways identified by profiling which allow tumours to survive or gain resistance to treatments. Here, we discuss recent advances in novel therapies that impact the genome (chromosomes and chromatin), pathways targeted and the stage of the pathways targeted. The current state of research will be discussed, with a focus on compounds that have advanced into trials (clinical and pre-clinical). We will discuss inhibitors of specific DNA damage responses and other genome stability pathways, including those in development, which are likely to synergistically combine with current therapeutic options. Tumour profiling data, combined with the knowledge of new treatments that affect the regulation of essential tumour signalling pathways, is revealing fundamental insights into cancer progression and resistance mechanisms. This is the forefront of the next evolution of advanced oncology medicine that will ultimately lead to improved survival and may, one day, result in many cancers becoming chronic conditions, rather than fatal diseases.

Targeting DNA Methyltranferases in Urological Tumors

Urological cancers are a heterogeneous group of malignancies accounting for a considerable proportion of cancer-related morbidity and mortality worldwide. Aberrant epigenetic traits, especially altered DNA methylation patterns constitute a hallmark of these tumors. Nonetheless, these alterations are reversible, and several efforts have been carried out to design and test several epigenetic compounds that might reprogram tumor cell phenotype back to a normal state. Indeed, several DNMT inhibitors are currently under evaluation for therapeutic efficacy in clinical trials. This review highlights the critical role of DNA methylation in urological cancers and summarizes the available data on pre-clinical assays and clinical trials with DNMT inhibitors in bladder, kidney, prostate, and testicular germ cell cancers.

HDAC1 controls CIP2A transcription in human colorectal cancer cells

This work describes the effectiveness of HDAC-inhibitor (S)-2 towards colorectal cancer (CRC) HCT116 cells in vitro by inducing cell cycle arrest and apoptosis, and in vivo by contrasting tumour growth in mice xenografts. Among the multifaceted drug-induced events described herein, an interesting link has emerged between the oncoprotein histone deacetylase HDAC1 and the oncogenic Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A) which is overexpressed in several cancers including CRCs. HDAC1 inhibition by (S)-2 or specific siRNAs downregulates CIP2A transcription in three different CRC cell lines, thus restoring the oncosuppressor phosphatase PP2A activity that is reduced in most cancers. Once re-activated, PP2A dephosphorylates pGSK-3β(ser9) which phosphorylates β-catenin that remains within the cytosol where it undergoes degradation. The decreased amount/activity of β-catenin transcription factor prompts cell growth arrest by diminishing c-Myc and cyclin D1 expression and abrogating the prosurvival Wnt/β-catenin signaling pathway. These results are the first evidence that the inhibition of HDAC1 by (S)-2 downregulates CIP2A transcription and unleashes PP2A activity, thus inducing growth arrest and apoptosis in CRC cells.

CXCR1/2 pathways in paclitaxel-induced neuropathic pain

Chemotherapy-induced peripheral neuropathy (CIPN) is a type of neuropathic pain that represents a frequent and serious consequence of chemotherapy agents. Over the last years, significant progress has been achieved in elucidating the underlying pathogenesis of CIPN. The interference of taxanes with microtubule has been proposed as a mechanism that leads to altered axonal transport and to permanent neurological damages. The inflammatory process activated by chemotherapeutic agents has been considered as a potential trigger of nociceptive process in CIPN.

In this study we investigated the effect of reparixin, an inhibitor of CXCR1/CXCR2, in suppressing the development of paclitaxel-induced nociception in rats. Moreover, reparixin activity in reversing the neurotoxic effects induced by paclitaxel or GRO/KC in F11 cells was also analyzed.

Reparixin administered by continuous infusion ameliorated paclitaxel-induced mechanical and cold allodynia in rats. In F11 cells, reparixin was able to inhibit the increase of acetyladed α-tubulin induced both by paclitaxel and GRO/KC. The subsequent experiments were performed in order to dissect the signal transduction pathways under GRO/KC control, eventually modulated by paclitaxel and/or reparixin. To this aim we found that reparixin significantly counteracted p-FAK, p-JAK2/p-STAT3, and PI3K-p-cortactin activation induced either by paclitaxel or GRO/KC.

Overall the present results have identified IL-8/CXCR1/2 pathway as a mechanism involved in paclitaxel-induced peripheral neuropathy. In particular, the obtained data suggest that the inhibition of CXCR1/2 combined with standard taxane therapy, in addition to potentiating the taxane anti-tumor activity can reduce chemotherapy-induced neurotoxicity, thus giving some insight for the development of novel treatments.

Inhibition studies of DNA methyltransferases by maleimide derivatives of RG108 as non-nucleoside inhibitors

AIM

DNA methyltransferases (DNMTs) are important drug targets for epigenetic therapy of cancer. Nowadays, non-nucleoside DNMT inhibitors are in development to address high toxicity of nucleoside analogs. However, these compounds still have low activity in cancer cells and mode of action of these compounds remains unclear.

MATERIALS & METHODS

In this work, we studied maleimide derivatives of RG108 by biochemical, structural and computational approaches to highlight their inhibition mechanism on DNMTs.

RESULTS

Findings demonstrated a correlation between cytotoxicity on mesothelioma cells of these compounds and their inhibitory potency against DNMTs. Noncovalent and covalent docking studies, supported by crystallographic (apo structure of M.HhaI) and differential scanning fluorimetry assays, provided detailed insights into their mode of action and revealed essential residues for the stabilization of such compounds inside DNMTs. [Formula: see text].

Research Priorities for Endometriosis

The 3rd International Consensus Workshop on Research Priorities in Endometriosis was held in São Paulo on May 4, 2014, following the 12th World Congress on Endometriosis. The workshop was attended by 60 participants from 19 countries and was divided into 5 main sessions covering pathogenesis/pathophysiology, symptoms, diagnosis/classification/prognosis, disease/symptom management, and research policy. This research priorities consensus statement builds on earlier efforts to develop research directions for endometriosis. Of the 56 research recommendations from the 2011 meeting in Montpellier, a total of 41 remained unchanged, 13 were updated, and 2 were deemed to be completed. Fifty-three new research recommendations were made at the 2014 meeting in Sao Paulo, which in addition to the 13 updated recommendations resulted in a total of 66 new recommendations for research. The research recommendations published herein, as well as those from the 2 previous papers from international consensus workshops, are an attempt to promote high-quality research in endometriosis by identifying and agreeing on key issues that require investigation. New areas included in the 2014 recommendations include infertility, patient stratification, and research in emerging nations, in addition to an increased focus on translational research. A revised and updated set of research priorities that builds on this document will be developed at the 13th World Congress on Endometriosis to be held on May 17-20, 2017, in Vancouver, British Columbia, Canada.

Epigenetic Treatment of Neuropsychiatric Disorders: Autism and Schizophrenia

Neuropsychiatric disorders are a heterogeneous group of conditions that often share underlying mitochondrial dysfunction and biological pathways implicated in their pathogenesis, progression, and treatment. To date, these disorders have proven notoriously resistant to molecular-targeted therapies, and clinical options are relegated to interventional types, which do not address the core symptoms of the disease. In this review, we discuss emerging epigenetic-driven approaches using novel acylcarnitine esters (carnitinoids) that act on master regulators of antioxidant and cytoprotective genes and mitophagic pathways. These carnitinoids are actively transported, mitochondria-localizing, biomimetic coenzyme A surrogates of short-chain fatty acids, which inhibit histone deacetylase and may reinvigorate synaptic plasticity and protect against neuronal damage. We outline these neuroprotective effects in the context of treatment of neuropsychiatric disorders such as autism spectrum disorder and schizophrenia.

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.

4,5-Diaryl imidazoles with hydroxamic acid appendages as anti-hepatoma agents

INTRODUCTION

Hepatocellular carcinoma (HCC) is the most abundant tumour of the liver with rising patient numbers in the Western world countries. Despite newly approved drugs like protein kinase inhibitors the survival rate is still poor.

METHODS

In order to identify potential new drugs for the treatment of HCC we investigated the real-time cell viability, apoptosis induction (sub-G1 cells), and HDAC (histone deacetylase) activity of two hepatocellular cancer cell lines HepG2 and Hep3B treated with new imidazole-tethered hydroxamates.

RESULTS

The tested cinnamyl hydroxamates exhibited significant antiproliferative and cytotoxic activity in HCC cells as apparent from high sub-G1 cell levels in flow cytometric cell cycle analyses. In Hep3B cells HDAC inhibition was observed comparable in magnitude to that induced by the clinically applied HDAC inhibitor SAHA (Zolinza, Vorinostat).

CONCLUSIONS

The new imidazolyl hydroxamic acids lend themselves as a possible alternative to SAHA in the therapy of HCC. Even more so since similar 4,5-diarylimidazoles lacking only the hydroxamate functionality were previously shown in animal studies to be well tolerated and orally applicable.

Quality control and statistical modeling for environmental epigenetics: a study on in utero lead exposure and DNA methylation at birth

DNA methylation data assayed using pyrosequencing techniques are increasingly being used in human cohort studies to investigate associations between epigenetic modifications at candidate genes and exposures to environmental toxicants and to examine environmentally-induced epigenetic alterations as a mechanism underlying observed toxicant-health outcome associations. For instance, in utero lead (Pb) exposure is a neurodevelopmental toxicant of global concern that has also been linked to altered growth in human epidemiological cohorts; a potential mechanism of this association is through alteration of DNA methylation (e.g., at growth-related genes). However, because the associations between toxicants and DNA methylation might be weak, using appropriate quality control and statistical methods is important to increase reliability and power of such studies. Using a simulation study, we compared potential approaches to estimate toxicant-DNA methylation associations that varied by how methylation data were analyzed (repeated measures vs. averaging all CpG sites) and by method to adjust for batch effects (batch controls vs. random effects). We demonstrate that correcting for batch effects using plate controls yields unbiased associations, and that explicitly modeling the CpG site-specific variances and correlations among CpG sites increases statistical power. Using the recommended approaches, we examined the association between DNA methylation (in LINE-1 and growth related genes IGF2, H19 and HSD11B2) and 3 biomarkers of Pb exposure (Pb concentrations in umbilical cord blood, maternal tibia, and maternal patella), among mother-infant pairs of the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort (n = 247). Those with 10 μg/g higher patella Pb had, on average, 0.61% higher IGF2 methylation (P = 0.05). Sex-specific trends between Pb and DNA methylation (P < 0.1) were observed among girls including a 0.23% increase in HSD11B2 methylation with 10 μg/g higher patella Pb.

ARHGEF3 controls HDACi-induced differentiation via RhoA-dependent pathways in acute myeloid leukemias

Altered expression and activity of histone deacetylases (HDACs) have been correlated with tumorigenesis. Inhibitors of HDACs (HDACi) induce acetylation of histone and non-histone proteins affecting gene expression, cell cycle progression, cell migration, terminal differentiation and cell death. Here, we analyzed the regulation of ARHGEF3, a RhoA-specific guanine nucleotide exchange factor, by the HDACi MS275 (entinostat). MS275 is a well-known benzamide-based HDACi, which induces differentiation of the monoblastic-like human histiocytic lymphoma cell line U937 to monocytes/macrophages. Incubation of U937 cells with MS275 resulted in an up regulation of ARHGEF3, followed by a significant enhancement of the marker of macrophage differentiation CD68. ARHGEF3 protein is primarily nuclear, but MS275 treatment rapidly induced its translocation into the cytoplasm. ARHGEF3 cytoplasmic localization is associated with activation of the RhoA/Rho-associated Kinase (ROCK) pathway. In addition to cytoskeletal rearrangements orchestrated by RhoA, we showed that ARHGEF3/RhoA-dependent signals involve activation of SAPK/JNK and then Elk1 transcription factor. Importantly, MS275-induced CD68 expression was blocked by exposure of U937 cells to exoenzyme C3 transferase and Y27632, inhibitors of Rho and ROCK respectively. Moreover, ARHGEF3 silencing prevented RhoA activation leading to a reduction in SAPK/JNK phosphorylation, Elk1 activation and CD68 expression, suggesting a crucial role for ARHGEF3 in myeloid differentiation. Taken together, our results demonstrate that ARHGEF3 modulates acute myeloid leukemia differentiation through activation of RhoA and pathways directly controlled by small GTPase family proteins. The finding that GEF protein modulation by HDAC inhibition impacts on cell differentiation may be important for understanding the antitumor mechanism(s) by which HDACi treatment stimulates differentiation in cancer.

Biological evaluation of 4,5-diarylimidazoles with hydroxamic acid appendages as novel dual mode anticancer agents

PURPOSE

New (4-aryl-1-methylimidazol-5-yl)cinnamoylhydroxamic acids were prepared as potential dual mode anticancer agents combining the antivascular effect of the 4,5-diarylimidazole moiety and the histone deacetylases (HDAC) inhibition by the cinnamoyl hydroxamate.

METHODS

Their antiproliferative activity against a panel of primary cells and cancer cell lines was determined by MTT assays and their apoptosis induction by caspase-3 activation. Their ability to reduce the activity of HDAC was measured by enzymatic assays and Western blot analyses of cellular HDAC substrates. Additional effects on cancer cell migration were ascertained via immunofluorescence staining of cytoskeleton components and three-dimensional migration assays. The chorioallantoic membrane assay was used as an in vivo model to assess their antiangiogenic properties.

RESULTS

The 4-phenyl- and 4-(p-methoxyphenyl)-imidazole derivatives had a greater antiproliferative and apoptosis inducing effect in a variety of cancer cell lines when compared with the approved HDAC inhibitor SAHA, and most distinctly so in non-malignant human umbilical vein endothelial cells. Like SAHA, both compounds acted as pan-HDAC inhibitors. In 518A2 melanoma cells, they led to hyperacetylation of histones and of the cytoplasmic HDAC6 substrate alpha-tubulin. As a consequence, they inhibited the migration and invasion of these cells in transwell invasion assays. In keeping with its pronounced impact on endothelial cells, the 4-phenyl-imidazole derivative also inhibited the growth and sprouting of blood vessels in the chorioallantoic membrane of fertilized hen eggs.

CONCLUSIONS

The 4-phenyl- and 4-(p-methoxyphenyl)-imidazole compounds combine the antivascular effects of 4,5-diarylimidazoles with HDAC inhibition by cinnamoyl hydroxamates and show additional antimetastatic activity. They are promising candidates for pleiotropic HDAC inhibitors.

HDAC Inhibitors: A New Radiosensitizer for Non-small-cell Lung Cancer

For many decades, lung cancer has been the most common cancer and the leading cause of cancer death worldwide. More than 50% of non-small-cell lung cancer patients receive radiotherapy (alone or in combination with chemotherapy or surgery) during their treatment. The intrinsic radiosensitivity of tumors and dose-limiting toxicity restrict the curative potential of radiotherapy. Histone deacetylase inhibitors (HDACis) are an emerging class of agents that target histone deacetylase and represent promising radiosensitizers that affect various biological processes, such as cell growth, apoptosis, DNA repair, and terminal differentiation. Histone deacetylase inhibitors have been found to suppress many important DNA damage responses by downregulating proteins in the homologous recombination and nonhomologous end joining repair pathways in vitro. In this review, we describe the rationale for using HDACis as radiosensitizers and the clinical evidence regarding the use of HDACis for the treatment of non-small-cell lung cancer.

HDAC-inhibitor (S)-8 disrupts HDAC6-PP1 complex prompting A375 melanoma cell growth arrest and apoptosis

Histone deacetylase inhibitors (HDACi) are agents capable of inducing growth arrest and apoptosis in different tumour cell types. Previously, we reported a series of novel HDACi obtained by hybridizing SAHA or oxamflatin with 1,4-benzodiazepines. Some of these hybrids proved effective against haematological and solid cancer cells and, above all, compound (S)-8 has emerged for its activities in various biological systems. Here, we describe the effectiveness of (S)-8 against highly metastatic human A375 melanoma cells by using normal PIG1 melanocytes as control. (S)-8 prompted: acetylation of histones H3/H4 and α-tubulin; G₀/G₁ and G₂/M cell cycle arrest by rising p21 and hypophos-phorylated RB levels; apoptosis involving the cleavage of PARP and caspase 9, BAD protein augmentation and cytochrome c release; decrease in cell motility, invasiveness and pro-angiogenic potential as shown by results of wound-healing assay, down-regulation of MMP-2 and VEGF-A/VEGF-R2, besides TIMP-1/TIMP-2 up-regulation; and also intracellular accumulation of melanin and neutral lipids. The pan-caspase inhibitor Z-VAD-fmk, but not the antioxidant N-acetyl-cysteine, contrasted these events. Mechanistically, (S)-8 allows the disruption of cytoplasmic HDAC6-protein phosphatase 1 (PP1) complex in A375 cells thus releasing the active PP1 that dephosphorylates AKT and blocks its downstream pro-survival signalling. This view is consistent with results obtained by: inhibiting PP1 with Calyculin A; using PPP1R2-transfected cells with impaired PP1 activity; monitoring drug-induced HDAC6-PP1 complex re-shuffling; and, abrogating HDAC6 expression with specific siRNA. Altogether, (S)-8 proved very effective against melanoma A375 cells, but not normal melanocytes, and safe to normal mice thus offering attractive clinical prospects for treating this aggressive malignancy.

Understanding gene regulatory mechanisms by integrating ChIP-seq and RNA-seq data: statistical solutions to biological problems

The availability of omic data produced from international consortia, as well as from worldwide laboratories, is offering the possibility both to answer long-standing questions in biomedicine/molecular biology and to formulate novel hypotheses to test. However, the impact of such data is not fully exploited due to a limited availability of multi-omic data integration tools and methods. In this paper, we discuss the interplay between gene expression and epigenetic markers/transcription factors. We show how integrating ChIP-seq and RNA-seq data can help to elucidate gene regulatory mechanisms. In particular, we discuss the two following questions: (i) Can transcription factor occupancies or histone modification data predict gene expression? (ii) Can ChIP-seq and RNA-seq data be used to infer gene regulatory networks? We propose potential directions for statistical data integration. We discuss the importance of incorporating underestimated aspects (such as alternative splicing and long-range chromatin interactions). We also highlight the lack of data benchmarks and the need to develop tools for data integration from a statistical viewpoint, designed in the spirit of reproducible research.

Epigenetic therapy as a novel approach in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver malignancy and one with high fatality. Its 5-year survival rate remains low and thus, there is a need for improvement of current treatment strategies as well as development of novel targeted methodologies in order to optimize existing therapeutic protocols. To this end, only recently, it was discovered that its pathophysiology also involves epigenetic alterations in DNA methylation, histone modifications and/or non-coding microRNA patterns. Unlike genetic events, epigenetic alterations are reversible and thus potentially considered to be an alternative option in cancer treatment protocols. In this review, we describe the general characteristics and resulted major alterations of the epigenetic machinery as well as current state of progress of epigenetic therapy (via different single or combinatorial experimental approaches) in HCC.