Small-molecule chromatin-modifying agents: therapeutic applications

Artificial Intelligence Applications in Oral Cancer and Oral Dysplasia

Oral squamous cell carcinoma (OSCC) is a highly unpredictable disease with devastating mortality rates that have not changed over the past decades, in the face of advancements in treatments and biomarkers, which have improved survival for other cancers. Delays in diagnosis are frequent, leading to more disfiguring treatments and poor outcomes in patients. The clinical challenge lies in identifying those patients at highest risk for developing OSCC. Oral epithelial dysplasia (OED) is a precursor of OSCC with highly variable behavior across patients. There is no reliable clinical, pathologic, histologic or molecular biomarker to determine individual risk in OED patients. Similarly, there are no robust biomarkers to predict treatment outcomes or mortality of OSCC patients. This review aims to highlight advancements in artificial intelligence (AI)-based methods to develop predictive biomarkers of OED transformation to OSCC or predictive biomarkers of OSCC mortality and treatment response. Machine-learning based biomarkers, such as S100A7, demonstrate promising appraisal for the risk of malignant transformation of OED. Machine learning-enhanced multiplex immunohistochemistry (mIHC) workflows examine immune cell patterns and organization within the tumor immune microenvironment to generate outcome predictions in immunotherapy. Deep learning (DL) is an AI-based method using an extended neural network or related architecture with multiple "hidden" layers of simulated neurons to combine simple visual features into complex patterns. DL-based digital pathology is currently being developed to assess OED and OSCC outcomes. The integration of machine learning in epigenomics aims to examine the epigenetic modification of diseases and improve our ability to detect, classify, and predict outcomes associated with epigenetic marks. Collectively, these tools showcase promising advancements in discovery and technology, which may provide a potential solution to addressing the current limitations in predicting OED transformation and OSCC behavior, both of which are clinical challenges that must be addressed in order to improve OSCC survival.

Mechanisms of mesothelial cell response to viral infections: HDAC1-3 inhibition blocks poly(I:C)-induced type I interferon response and modulates the mesenchymal/inflammatory phenotype

Infectious peritonitis is a leading cause of peritoneal functional impairment and a primary factor for therapy discontinuation in peritoneal dialysis (PD) patients. Although bacterial infections are a common cause of peritonitis episodes, emerging evidence suggests a role for viral pathogens. Toll-like receptors (TLRs) specifically recognize conserved pathogen-associated molecular patterns (PAMPs) from bacteria, viruses, and fungi, thereby orchestrating the ensuing inflammatory/immune responses. Among TLRs, TLR3 recognizes viral dsRNA and triggers antiviral response cascades upon activation. Epigenetic regulation, mediated by histone deacetylase (HDAC), has been demonstrated to control several cellular functions in response to various extracellular stimuli. Employing epigenetic target modulators, such as epidrugs, is a current therapeutic option in several cancers and holds promise in treating viral diseases. This study aims to elucidate the impact of TLR3 stimulation on the plasticity of human mesothelial cells (MCs) in PD patients and to investigate the effects of HDAC1-3 inhibition. Treatment of MCs from PD patients with the TLR3 agonist polyinosinic:polycytidylic acid (Poly(I:C)), led to the acquisition of a bona fide mesothelial-to-mesenchymal transition (MMT) characterized by the upregulation of mesenchymal genes and loss of epithelial-like features. Moreover, Poly(I:C) modulated the expression of several inflammatory cytokines and chemokines. A quantitative proteomic analysis of MCs treated with MS-275, an HDAC1-3 inhibitor, unveiled altered expression of several proteins, including inflammatory cytokines/chemokines and interferon-stimulated genes (ISGs). Treatment with MS-275 facilitated MMT reversal and inhibited the interferon signature, which was associated with reduced STAT1 phosphorylation. However, the modulation of inflammatory cytokine/chemokine production was not univocal, as IL-6 and CXCL8 were augmented while TNF-α and CXCL10 were decreased. Collectively, our findings underline the significance of viral infections in acquiring a mesenchymal-like phenotype by MCs and the potential consequences of virus-associated peritonitis episodes for PD patients. The observed promotion of MMT reversal and interferon response inhibition by an HDAC1-3 inhibitor, albeit without a general impact on inflammatory cytokine production, has translational implications deserving further analysis.

HDAC1-3 inhibition increases SARS-CoV-2 replication and productive infection in lung mesothelial and epithelial cells

Background

Despite the significant progress achieved in understanding the pathology and clinical management of SARS-CoV-2 infection, still pathogenic and clinical issues need to be clarified. Treatment with modulators of epigenetic targets, i.e., epidrugs, is a current therapeutic option in several cancers and could represent an approach in the therapy of viral diseases.

Results

Aim of this study was the analysis of the role of histone deacetylase (HDAC) inhibition in the modulation of SARS-CoV-2 infection of mesothelial cells (MCs).MeT5A cells, a pleura MC line, were pre-treated with different specific class I and IIb HDAC inhibitors. Unexpectedly, treatment with HDAC1-3 inhibitors significantly increased ACE2/TMPRSS2 expression, suggesting a role in favoring SARS-CoV-2 infection. We focused our analysis on the most potent ACE2/TMPRSS2 inducer among the inhibitors analysed, MS-275, a HDAC1-3 inhibitor. ACE2/TMPRSS2 expression was validated by Western Blot (WB) and immunofluorescence. The involvement of HDAC inhibition in receptor induction was confirmed by HDAC1/HDAC2 silencing. In accordance to the ACE2/TMPRSS2 expression data, MS-275 increased SARS-CoV-2 replication and virus propagation in Vero E6 cells.Notably, MS-275 was able to increase ACE2/TMPRSS2 expression and SARS-CoV-2 production, although to a lesser extent, also in the lung adenocarcinoma cell line Calu-3 cells.Mechanistically, treatment with MS-275 increased H3 and H4 histone acetylation at ACE2/TMPRSS2 promoters, increasing their transcription.

Conclusion

This study highlights a previously unrecognized effect of HDAC1-3 inhibition in increasing SARS-CoV-2 cell entry, replication and productive infection correlating with increased expression of ACE2 and TMPRSS2. These data, while adding basic insight into COVID-19 pathogenesis, warn for the use of HDAC inhibitors in SARS-CoV-2 patients.

Histone deacetylase 10: A polyamine deacetylase from the crystal structure to the first inhibitors

Polyamine deacetylase activity was discovered more than 40 years ago, but the responsible histone deacetylase 10 (HDAC10) was described only recently. HDAC10 is a class IIb HDAC, as is its closest relative, the α-tubulin deacetylase HDAC6. HDAC10 has attracted attention over the last 2 years due to its role in diseases, especially cancer. This review summarises chemical and structural biology approaches to the study of HDAC10. Light will be shed on recent advances in understanding the complex structural biology of HDAC10 and the discovery of the first highly selective HDAC10 inhibitors.

Novel pyridine-containing histone deacetylase inhibitors strongly arrest proliferation, induce apoptosis and modulate miRNAs in cancer cells

After over 30 years of research, the development of HDAC inhibitors led to five FDA/Chinese FDA-approved drugs and many others under clinical or preclinical investigation to treat cancer and non-cancer diseases. Herein, based on our recent development of pyridine-based isomers as HDAC inhibitors, we report a series of novel 5-acylamino-2-pyridylacrylic- and -picolinic hydroxamates and 2'-aminoanilides 5-8 as anticancer agents. The hydroxamate 5d proved to be quite HDAC3/6-selective exhibiting IC₅₀ values of 80 and 11 nM, respectively, whereas the congener 5e behaved as inhibitor of HDAC1-3, -6, -8, and -10 (class I/IIb-selective inhibitor) at nanomolar level. Compound 5e provided a huge antiproliferative activity (nanomolar IC₅₀ values) against both haematological and solid cancer cell lines. In leukaemia U937 cells, the hydroxamate 5d and the 2'-aminoanilide 8f induced remarkable cell death after 48 h, with 76% and 100% pre-G1 phase arrest, respectively, showing a stronger effect with respect to SAHA and MS-275 used as reference compounds. In U937 cells, the highest dose- and time-dependent cytodifferentiation was obtained by the 2'-aminoanilide 8d (up to 35% of CD11c positive/propidium iodide negative cells at 5 μM for 48 h). The same 8d and the hydroxamates 5d and 5e were the most effective in inducing p21 protein expression in the same cell line. Mechanistically, 5d, 5e, 8d and 8f increased mRNA expression of p21, BAX and BAK, downregulated cyclin D1 and BCL-2 and modulated pro- and anti-apoptotic microRNAs towards apoptosis induction. Finally, 5e strongly arrested proliferation in nine different haematological cancer cell lines, with dual-digit nanomolar potency towards MV4-11, Kasumi-1, and NB4, being more potent than mocetinostat, used as reference drug.

Purine/purine isoster based scaffolds as new derivatives of benzamide class of HDAC inhibitors

This study reports the design, synthesis and evaluation of a series of histone deacetylase (HDAC) inhibitors containing purine/purine isoster as a capping group and an N-(2-aminophenyl)-benzamide unit. In vitro cytotoxicity studies reveal that benzamide 14 suppressed the growth of triple-negative breast cancer cells MDA-MB-231 (IC₅₀ = 1.48 μM), MDA-MB-468 (IC₅₀ = 0.65 μM), and liver cancer cells HepG2 (IC₅₀ = 2.44 μM), better than MS-275 (5) and Chidamide (6). Compared to the well-known HDAC inhibitor SAHA, 14 showed a higher toxicity (IC₅₀ = 0.33 μM) in three leukemic cell lines, K-562, KG-1 and THP-1. Moreover, 14 was found to be equally virulent in the HDAC-sensitive and -resistant gastric cell lines, YCC11 and YCC3/7, respectively, indicating the potential of 14 to overcome HDACi resistance. Furthermore, substantial inhibitory effects more pronounced than MS-275 (5) and Chidamide (6) were displayed by 14 towards HDAC1, 2 and 3 isoforms with IC₅₀ values of 0.108, 0.585 and 0.563 μM respectively. Compound 14 also exhibited a potent antitumor efficacy in human MDA-MB-231 breast cancer xenograft mouse model, providing a potential lead for the development of anticancer agents.

Discovery of 1,2,4-oxadiazole-Containing hydroxamic acid derivatives as histone deacetylase inhibitors potential application in cancer therapy

In this study, a series of novel HDAC inhibitors, using 1,2,4-oxadiazole-containing as the cap group, were synthesized and evaluated in vitro. Compound 14b, N-hydroxy-2-(methyl((3-(1-(4-methylbenzyl)piperidin-4-yl)-1,2,4-oxadiazol-5-yl)methyl)amino)pyrimidine-5-carboxamide, displayed the most potent histone deacetylase (HDAC) inhibition, especially against HDAC1, 2, and 3 with IC₅₀ values of 1.8, 3.6 and 3.0 nM, respectively. In vitro antiproliferative studies confirmed that 14b was more potent than SAHA, with IC₅₀ values against 12 types of cancer cell lines ranging from 9.8 to 44.9 nM. The results of Western blot assays showed that compound 14b can significantly up-regulate the acetylation of the biomarker his-H₃ and molecular docking analyses revealed the mode of action of compound 14b against HDAC1. The results of flow-cytometry analysis suggested that compound 14b induces cell cycle arrest at the G1 phase and has apoptotic effects. Further investigation of the activity of 14b on the primary cells of three patients, showed IC₅₀ values of 21.3, 61.1, and 77.4 nM. More importantly, an oral bioavailability of up to 53.52% was observed for 14b. An in vivo pharmacodynamic evaluation demonstrated that compound 14b can significantly inhibit tumor growth in a Daudi Burkitt's lymphoma xenograft model, with tumor inhibition rates of 53.8 and 46.1% observed at 20 and 10 mg/kg when administered p.o. and i.v., respectively. These results indicate that compound 14b may be a suitable lead for further evaluation and development as an HDAC inhibitor and a potent anticancer agent.

Methods for Hydroxamic Acid Synthesis

Substituted hydroxamic acid is one of the most extensively studied pharmacophores because of their ability to chelate biologically important metal ions to modulate various enzymes, such as HDACs, urease, metallopeptidase, and carbonic anhydrase. Syntheses and biological studies of various classes of hydroxamic acid derivatives have been reported in numerous research articles in recent years but this is the first review article dedicated to their synthetic methods and their application for the synthesis of these novel molecules. In this review article, commercially available reagents and preparation of hydroxylamine donating reagents have also been described.

Novel Agents and Drug Targets to Meet the Challenges of Resistant Fungi

The emergence of drug-resistant fungi poses a major threat to human health. Despite advances in preventive, diagnostic, and therapeutic interventions, resistant fungal infections continue to cause significant morbidity and mortality in patients with compromised immunity, underscoring the urgent need for new antifungal agents. In this article, we review the challenges associated with identifying broad-spectrum antifungal drugs and highlight novel targets that could enhance the armamentarium of agents available to treat drug-resistant invasive fungal infections.

The histone deacetylase sirtuin 2 is a new player in the regulation of platelet function

BACKGROUND

Histone deacetylases (HDACs) play a key role in signaling in many cell types. However, little is known about the participation of HDACs, particularly sirtuins (SIRTs), in platelet reactivity.

OBJECTIVE

To investigate the role of HDACs in platelets, we examined the effects of SIRT inhibition on platelet function and protein acetylation in human platelets.

METHODS

We used washed platelets obtained from healthy subjects. Cambinol (SIRT1 and SIRT2 inhibitor), AGK2 (specific SIRT2 inhibitor) and EX527 (specific SIRT1 inhibitor) were used as SIRT inhibitors. Platelets were stimulated with collagen, thrombin, or U46619, and platelet responses were determined according to optical aggregometry findings, dense granule release, and cytosolic calcium levels (Fura-2AM fluorescence). Protein acetylation and phosphorylation were assessed by immunoblotting.

RESULTS

SIRT inhibition remarkably reduced platelet responses (aggregation, granule release, and cytosolic calcium level; P < 0.05). SIRT2 was present in platelets at the level of mRNA and protein, and its specific inhibition reduced platelet responses. The acetylated protein pattern observed in resting platelets changed during platelet aggregation. Inhibition of SIRT2 increased the acetylation of Akt kinase, which in turn blocked agonist-induced Akt phosphorylation and glycogen synthase kinase-3β phosphorylation, which are markers of Akt activity. Finally, collagen-induced aggregation provoked Akt acetylation.

CONCLUSIONS

Regulation of protein acetylation by SIRT2 plays a central role in platelet function. The effects of SIRT2 are mediated in part by the acetylation and inhibition of Akt. These results open a new avenue for research into the control of platelet function, and may help to identify new therapeutic targets.

Adverse epigenetic signatures by histone methyltransferase Set7 contribute to vascular dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

Cellular studies showed that histone methyltransferase Set7 mediates high glucose-induced inflammation via epigenetic regulation of the transcription factor NF-kB. However, the link between Set7 and vascular dysfunction in patients with diabetes mellitus remains unknown. This study was designed to investigate whether Set7 contributes to vascular dysfunction in patients with type 2 diabetes mellitus (T2DM).

METHODS AND RESULTS

Set7-driven epigenetic changes on NF-kB p65 promoter and expression of NF-kB-dependent genes, cyclooxygenase 2 and inducible endothelial nitric oxide synthase, were assessed in peripheral blood mononuclear cells isolated from 68 subjects (44 patients with T2DM and 24 age-matched controls). Brachial artery flow-mediated dilation, 24-hour urinary levels of 8-isoprostaglandin F2α, and plasma adhesion molecules, intercellular cell adhesion molecule-1 and monocyte chemoattractant protein-1, were also determined. Experiments in human aortic endothelial cells exposed to high glucose were performed to elucidate the mechanisms of Set7-driven inflammation and oxidative stress. Set7 expression increased in peripheral blood mononuclear cells from patients with T2DM when compared with controls. Patients with T2DM showed Set7-dependent monomethylation of lysine 4 of histone 3 on NF-kB p65 promoter. This epigenetic signature was associated with upregulation of NF-kB, subsequent transcription of oxidant/inflammatory genes, and increased plasma levels of intercellular cell adhesion molecule-1 and monocyte chemoattractant protein-1. Interestingly, we found that Set7 expression significantly correlated with oxidative marker 8-isoprostaglandin F2α (r=0.38; P=0.01) and flow-mediated dilation (r=-0.34; P=0.04). In human aortic endothelial cells, silencing of Set7 prevented monomethylation of lysine 4 of histone 3 and abolished NF-kB-dependent oxidant and inflammatory signaling.

CONCLUSIONS

Set7-induced epigenetic changes contribute to vascular dysfunction in patients with T2DM. Targeting this chromatin-modifying enzyme may represent a novel therapeutic approach to prevent atherosclerotic vascular disease in this setting.

Emerging drugs and vaccines for candidemia

Candidemia and other forms of invasive candidiasis are important causes of morbidity and mortality. The evolving challenge of antimicrobial resistance among fungal pathogens continues to highlight the need for potent, new antifungal agents. MEDLINE, EMBASE, Scopus and Web of Science searches (up to January 2014) of the English-language literature were performed with the keywords 'Candida' or 'Candidemia' or 'Candidiasis' and terms describing investigational drugs with activity against Candida spp. Conference abstracts and the bibliographies of pertinent articles were also reviewed for relevant reports. ClinicalTrials.gov was searched for relevant clinical trials. Currently available antifungal agents for the treatment of candidemia are summarised. Investigational antifungal agents with potential activity against Candida bloodstream infections and other forms of invasive candidiasis and vaccines for prevention of Candida infections are also reviewed as are selected antifungal agents no longer in development. Antifungal agents currently in clinical trials include isavuconazole, albaconazole, SCY-078, VT-1161 and T-2307. Further data are needed to determine the role of these compounds in the treatment of candidemia and other forms of invasive candidiasis. The progressive reduction in antimicrobial drug development may result in a decline in antifungal drug discovery. Still, there remains a critical need for new antifungal agents to treat and prevent invasive candidiasis and other life-threatening mycoses.

1,3,4-Oxadiazole-containing histone deacetylase inhibitors: anticancer activities in cancer cells

We describe 1,3,4-oxadiazole-containing hydroxamates (2) and 2-aminoanilides (3) as histone deacetylase inhibitors. Among them, 2t, 2x, and 3i were the most potent and selective against HDAC1. In U937 leukemia cells, 2t was more potent than SAHA in inducing apoptosis, and 3i displayed cell differentiation with a potency similar to MS-275. In several acute myeloid leukemia (AML) cell lines, as well as in U937 cells in combination with doxorubicin, 3i showed higher antiproliferative effects than SAHA.

Epigenetic drug discovery for Alzheimer's disease

INTRODUCTION

It is assumed that epigenetic modifications are reversible and could potentially be targeted by pharmacological and dietary interventions. Epigenetic drugs are gaining particular interest as potential candidates for the treatment of Alzheimer's disease (AD).

AREAS COVERED

This article covers relevant information from over 50 different epigenetic drugs including: DNA methyltransferase inhibitors; histone deacetylase inhibitors; histone acetyltransferase modulators; histone methyltransferase inhibitors; histone demethylase inhibitors; non-coding RNAs (microRNAs) and dietary regimes. The authors also review the pharmacoepigenomics and the pharmacogenomics of epigenetic drugs. The readers will gain insight into i) the classification of epigenetic drugs; ii) the mechanisms by which these drugs might be useful in AD; iii) the pharmacological properties of selected epigenetic drugs; iv) pharmacoepigenomics and the influence of epigenetic drugs on genes encoding CYP enzymes, transporters and nuclear receptors; and v) the genes associated with the pharmacogenomics of anti-dementia drugs.

EXPERT OPINION

Epigenetic drugs reverse epigenetic changes in gene expression and might open future avenues in AD therapeutics. Unfortunately, clinical trials with this category of drugs are lacking in AD. The authors highlight the need for pharmacogenetic and pharmacoepigenetic studies to properly evaluate any efficacy and safety issues.

Properly substituted analogues of BIX-01294 lose inhibition of G9a histone methyltransferase and gain selective anti-DNA methyltransferase 3A activity

Chemical manipulations performed on the histone H3 lysine 9 methyltransferases (G9a/GLP) inhibitor BIX-01294 afforded novel desmethoxyquinazolines able to inhibit the DNA methyltransferase DNMT3A at low micromolar levels without any significant inhibition of DNMT1 and G9a. In KG-1 cells such compounds, when tested at sub-toxic doses, induced the luciferase re-expression in a stable construct controlled by a cytomegalovirus (CMV) promoter silenced by methylation (CMV-luc assay). Finally, in human lymphoma U-937 and RAJI cells, the N-(1-benzylpiperidin-4-yl)-2-(4-phenylpiperazin-1-yl)quinazolin-4-amine induced the highest proliferation arrest and cell death induction starting from 10 µM, in agreement with its DNMT3A inhibitory potency.

Evaluation of a large library of (thiazol-2-yl)hydrazones and analogues as histone acetyltransferase inhibitors: enzyme and cellular studies

Recently we described some (thiazol-2-yl)hydrazones as antiprotozoal, antifungal and anti-MAO agents as well as Gcn5 HAT inhibitors. Among these last compounds, CPTH2 and CPTH6 showed HAT inhibition in cells and broad anticancer properties. With the aim to identify HAT inhibitors more potent than the two prototypes, we synthesized several new (thiazol-2-yl)hydrazones including some related thiazolidines and pyrimidin-4(3H)-ones, and we tested the whole library existing in our lab against human p300 and PCAF HAT enzymes. Some compounds (1x, 1c', 1d', 1i' and 2m) were more efficient than CPTH2 and CPTH6 in inhibiting the p300 HAT enzyme. When tested in human leukemia U937 and colon carcinoma HCT116 cells (100 μM, 30 h), 1x, 1i' and 2m gave higher (U937 cells) or similar (HCT116 cells) apoptosis than CPTH6, and were more potent than CPTH6 in inducing cytodifferentiation (U937 cells).

Quinoline-based p300 histone acetyltransferase inhibitors with pro-apoptotic activity in human leukemia U937 cells

Chemical manipulations performed on 2-methyl-3-carbethoxyquinoline (1), a histone acetyltransferase inhibitor previously identified by our research group and active at the sub-millimolar/millimolar level, led to compounds bearing higher alkyl groups at the C2-quinoline or additional side chains at the C6-quinoline positions. Such compounds displayed at least threefold improved inhibitory potency toward p300 protein lysine acetyltransferase activity; some of them decreased histone H3 and H4 acetylation levels in U937 cells and induced high degrees of apoptosis (three compounds >10-fold higher than compound 1) after treatment of U937 cells.

CellFateScout - a bioinformatics tool for elucidating small molecule signaling pathways that drive cells in a specific direction

Background

Small molecule effects can be represented by active signaling pathways within functional networks. Identifying these can help to design new strategies to utilize known small molecules, e.g. to trigger specific cellular transformations or to reposition known drugs.

Results

We developed CellFateScout that uses the method of Latent Variables to turn differential high-throughput expression data and a functional network into a list of active signaling pathways. Applying it to Connectivity Map data, i.e., differential expression data describing small molecule effects, we then generated a Human Small Molecule Mechanisms Database. Finally, using a list of active signaling pathways as query, a similarity search can identify small molecules from the database that may trigger these pathways. We validated our approach systematically, using expression data of small molecule perturbations, yielding better predictions than popular bioinformatics tools.

Conclusions

CellFateScout can be used to select small molecules for their desired effects. The CellFateScout Cytoscape plugin, a tutorial and the Human Small Molecule Mechanisms Database are available at https://sourceforge.net/projects/cellfatescout/ under LGPLv2 license.

tert-Butylcarbamate-containing histone deacetylase inhibitors: apoptosis induction, cytodifferentiation, and antiproliferative activities in cancer cells

Herein we report novel pyrrole- and benzene-based hydroxamates (8, 10) and 2'-aminoanilides (9, 11) bearing the tert-butylcarbamate group at the CAP moiety as histone deacetylase (HDAC) inhibitors. Compounds 8 b and 10 c selectively inhibited HDAC6 at the nanomolar level, whereas the other hydroxamates effected an increase in acetyl-α-tubulin levels in human acute myeloid leukemia U937 cells. In the same cell line, compounds 8 b and 10 c elicited 18.4 and 21.4 % apoptosis, respectively (SAHA: 16.9 %), and the pyrrole anilide 9 c displayed the highest cytodifferentiating effect (90.9 %). In tests against a wide range of various cancer cell lines to determine its antiproliferative effects, compound 10 c exhibited growth inhibition from sub-micromolar (neuroblastoma LAN-5 and SH-SY5Y cells, chronic myeloid leukemia K562 cells) to low-micromolar (lung H1299 and A549, colon HCT116 and HT29 cancer cells) concentrations. In HT29 cells, 10 c increased histone H3 acetylation, and decreased the colony-forming potential of the cancer cells by up to 60 %.

Developing novel non-hydroxamate histone deacetylaseinhibitors: the chelidamic warhead

The dimethyl 4-hydroxypyridine-2,6-dicarboxylate is a valuable scaffold for HDAC inhibitor design as a replacement of the well-known hydroxamate function.

Targeting Histone Demethylases: A New Avenue for the Fight against Cancer

In addition to genetic disorders, epigenetic alterations have been shown to be involved in cancer, through misregulation of histone modifications. Miswriting, misreading, and mis-erasing of histone acetylation as well as methylation marks can be actually associated with oncogenesis and tumor proliferation. Historically, methylation of Arg and Lys residues has been considered a stable, irreversible process due to the slow turnover of methyl groups in chromatin. The discovery in recent years of a large number of histone Lys demethylases (KDMs, belonging to either the amino oxidase or the JmjC family) totally changed this point of view and suggested a new role for dynamic histone methylation in biological processes. Since overexpression, alteration, or mutation of a number of KDMs has been found in many types of cancers, such enzymes could represent diagnostic tools as well as epigenetic targets to modulate for obtaining novel therapeutic weapons against cancer. The first little steps in this direction are described here.