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Thiomorpholine analogues of U-100480 with the biphenylmethyl group replacing the acetamidomethyloxazolidinone moiety have been synthesized and tested as antimycobacterial agents together with various related derivatives. Some biphenyl derivatives were endowed with high activity against Mycobacterium tuberculosis and other non-tuberculous mycobacteria.

Two 2,6-difluoro-DABO derivatives (MC 1047, 1, and MC 1220, 2, respectively) were tested against endogenous, nontelomeric reverse transcriptase (endo-RT) in human differentiating cell systems to investigate their antiproliferative and cytodifferentiating activity. The two compounds significantly reduced cell proliferation and facilitated the morphological differentiation of cells. These results propose F(2)-DABOs as useful tools in preventive and/or curative therapy to counteract the loss of differentiation in dedifferentiating pathologies and as antiproliferative drugs in tumor therapy.

International audience; Not widely distributed in nature, aurones, (Z)-2-benzylidene-benzofuran-3(2H)-ones, are one of the less common and lesser-known representatives of a flavonoid subclass. Nevertheless, they exhibit a strong and broad variety of biological activities. We have combined the benzofuranone part of a classical aurone with either a chromone or a coumarin scaffold which proved to feature interesting biological activities including antimicrobial, antiviral, anticancer, anti-inflammatory and antioxidant properties. Herein we present a series of 26 novel benzofuran derivatives with the first biological results in K562 human leukemia cells showing that compounds 21b, 29b and 29c are able to induce around 24% apoptosis.

The review describes the flourishing synthesis and brief structure-anti-HIV-1 activity relationships of 6-(arylmethyl)pyrimidin-4(3H)-one derivatives.

In the past few years sirtuins have gained growing attention for their involvement in many biological processes such as cellular metabolism, apoptosis, aging and inflammation. In this contribution, we report the synthesis of a library of thioacetylated pseudopeptides that were screened against human sirtuins 1–3 to reveal their in vitro inhibition activities. Molecular modeling studies were performed to acquire data about the binding modes of the inhibitors. Three sirtuin inhibitors were subjected to cellular studies, and all of them showed an increase in acetylation of Lys382 of p53 after DNA damage. Furthermore, two of the compounds were able to inhibit both A549 lung carcinoma and MCF-7 breast carcinoma cell growth in micromolar concentration with the ability to arrest cancer cell cycle in the G1 phase.

The combinatorial assembly of protein complexes is at the heart of chromatin biology. Lysine demethylase LSD1(KDM1A)/CoREST beautifully exemplifies this concept. The active site of the enzyme tightly associates to the N-terminal domain of transcription factors of the SNAIL1 family, which therefore can competitively inhibit the binding of the N-terminal tail of the histone substrate. Our enzymatic, crystallographic, spectroscopic, and computational studies reveal that LSD1/CoREST can bind to a hexapeptide derived from the SNAIL sequence through recognition of a positively charged α-helical turn that forms upon binding to the enzyme. Variations in sequence and length of this six amino acid ligand modulate affinities enabling the same binding site to differentially interact with proteins that exert distinct biological functions. The discovered short peptide inhibitors exhibit antiproliferative activities and lay the foundation for the development of peptidomimetic small molecule inhibitors of LSD1.

In a mouse model of skin repair we found that the class I-IIa histone deacetylase inhibitor trichostatin A accelerated tissue regeneration. Unexpectedly, this effect was suppressed by Sirtinol, a class III histone deacetylase (HDAC) (sirtuin)-selective inhibitor. The role of sirtuins (SIRTs) was then investigated by using resveratrol and a novel SIRT1-2-3 activator, the MC2562 compound we synthesized recently. Both resveratrol and MC2562 were effective in accelerating wound repair. The local administration of natural or synthetic SIRT activators, in fact, significantly accelerated skin regeneration by increasing keratinocyte proliferation. In vitro experiments revealed that the activation of SIRTs stimulated keratinocyte proliferation via endothelial NO synthase phosphorylation and NO production. In this condition, the class I member HDAC2 was found S-nitrosylated on cysteine, a post-transduction modification associated with loss of activity and DNA binding capacity. After deacetylase inhibitor or SIRT activator treatment, ChIP showed, in fact, a significant HDAC2 detachment from the promoter region of insulin growth factor I (IGF-I), fibroblast growth factor 10 (FGF-10), and Epithelial Growth Factor (EGF), which may be the final recipients and effectors of the SIRT-NO-HDAC signaling cascade. Consistently, the effect of SIRT activators was reduced in the presence of NG-nitro-L-arginine methyl ester (L-NAME), a general inhibitor of NO synthesis. In conclusion, the NO-dependent cross-talk among class III and I histone deacetylases suggests an unprecedented signaling pathway important for skin repair.

"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 %." 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 8b and 10c 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 8b and 10c elicited 18.4 and 21.4% apoptosis, respectively (SAHA: 16.9%), and the pyrrole anilide 9c displayed the highest cytodifferentiating effect (90.9%). In tests against a wide range of various cancer cell lines to determine its antiproliferative effects, compound 10c 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, 10c increased histone H3 acetylation, and decreased the colony-forming potential of the cancer cells by up to 60%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

BackgroundThe conversion of a quiescent vitamin A storing hepatic stellate cell (HSC) to a matrix producing, contractile myofibroblast-like activated HSC is a key event in the onset of liver disease following injury of any aetiology. Previous studies have shown that class I histone deacetylases (HDACs) are involved in the phenotypical changes occurring during stellate cell activation in liver and pancreas.AimsIn the current study we investigate the role of class II HDACs during HSC activation.MethodsWe characterized the expression of the class II HDACs freshly isolated mouse HSCs. We inhibited HDAC activity by selective pharmacological inhibition with MC1568, and by repressing class II HDAC gene expression using specific siRNAs.ResultsInhibition of HDAC activity leads to a strong reduction of HSC activation markers α-SMA, lysyl oxidase and collagens as well as an inhibition of cell proliferation. Knock down experiments showed that HDAC4 contributes to HSC activation by regulating lysyl oxidase expression. In addition, we observed a strong up regulation of miR-29, a well-known anti-fibrotic miR, upon treatment with MC1568. Our in vivo work suggests that a successful inhibition of class II HDACs could be promising for development of future anti-fibrotic compounds.ConclusionsIn conclusion, the use of MC1568 has enabled us to identify a role for class II HDACs regulating miR-29 during HSC activation.

A 3-D QSAR study has been carried out on a new class of potent and selective human rhinovirus-14 (HRV-14) inhibitors. In particular, the CoMFA (comparative molecular field analysis) technique has been applied to develop a model able to explain and predict the anti-HRV-14 activity of a class of compounds 4 and potentially helpful to design new and more potent antirhinovirus agents. Docking experiments have also been performed with the aim of elucidating the possible binding mode of these inhibitors. These two approaches are combined to highlight a single, highly favoured mode of interaction of the compounds with the viral capsid proteins.

Chemical changes performed on 1a (sirtinol) led to a series of SIRT1/2 inhibitors, in some cases more potent than 1a mainly against SIRT1. Tested in human leukemia U937 cells, the benzamide and anilide derivatives 1b, 1c, 2b, and 2c as well as the 4-(2-phenylpropyl)thioanalogue 4c showed huge apoptosis induction, while some sulfinyl and sulfonyl derivatives (5b, 5c, and 6a-c) were highly efficient in granulocytic differentiation. When assayed in human leukemia MOLT4 as well as in human breast MDA-MB-231 and colon RKO cancer cell lines, the anilide 2b (salermide) and the phenylpropylthio analogue 4b emerged as the most potent antiproliferative agents. Tested on colorectal carcinoma and glioblastoma multiforme cancer stem cells (CSCs) from patients, 2b was particularly potent against colorectal carcinoma CSCs, while 4b, 6a, and the SIRT2-selective inhibitor AGK-2 showed the highest effect against glioblastoma multiforme CSCs. Such compounds will be further explored for their broad-spectrum anticancer properties.

Ciliopathies are a group of autosomal recessive disorders, characterized by defect in central nervous system, that include several, partially overlapping, syndromes such Meckel-Gruber syndrome and COACH syndrome. Ciliopathies are caused by mutations in genes encoding protein of the primary cilium, as Jouberin and Meckelin (TMEM67). Meckelin is a receptor localized to the ciliary membrane and at the cell surface of polarized cells; it interacts with citoskeletal protein participating in ciliogenesis via remodelling of cytoskeleton. Histone Deacetylase (HDAC) 6 is a cytoplasmic deacetylase, that localize to microtubules in a variety of cultured cells, and participate in the deacetylation of the major component of the cilia axoneme, alpha-tubulin, a process that leads to reduced microtubule stability. Moreover, HDAC6 has also been implicated both in cilia resorption and disassembly, through its interaction with Aurora A kinase, that localize to basal bodies. In the present work we show that MKS3 interacts with HDAC6 in MKS3 overexpressing HEK293 cells and in ciliated IMCD3 cells. Moreover, we confirmed this interaction in mouse embryonic stem cells, used as an in vitro model of neurogenesis. In this cellular context, deacetylase activity assays performed on MKS3 immunoprecipitated complexes showed high HDAC activity, which was lost in the presence of a specific HDAC6 inhibitor. Altogether these results reveal an unpredictable interaction between Meckelin and HDAC6, shedding light on a putative, novel role of Meckelin in controlling ciliary microtubules acetylation/deacetylation and primary cilia stability.

The epigenetic silencing of exogenous transcriptional units integrated into the genome represents a critical problem both for long-term gene therapy efficacy and for the eradication of latent viral infections. We report here that limitation of essential amino acids, such as methionine and cysteine, causes selective up-regulation of exogenous transgene expression in mammalian cells. Prolonged amino acid deprivation led to significant and reversible increase in the expression levels of stably integrated transgenes transcribed by means of viral or human promoters in HeLa cells. This phenomenon was mediated by epigenetic chromatin modifications, because histone deacetylase (HDAC) inhibitors reproduced starvation-induced transgene up-regulation, and transcriptome analysis, ChIP, and pharmacological and RNAi approaches revealed that a specific class II HDAC, namely HDAC4, plays a critical role in maintaining the silencing of exogenous transgenes. This mechanism was also operational in cells chronically infected with HIV-1, the etiological agent of AIDS, in a latency state. Indeed, both amino acid starvation and pharmacological inhibition of HDAC4 promoted reactivation of HIV-1 transcription and reverse transcriptase activity production in HDAC4 + ACH-2 T-lymphocytic cells but not in HDAC4 − U1 promonocytic cells. Thus, amino acid deprivation leads to transcriptional derepression of silenced transgenes, including integrated plasmids and retroviruses, by a process involving inactivation or down-regulation of HDAC4. These findings suggest that selective targeting of HDAC4 might represent a unique strategy for modulating the expression of therapeutic viral vectors, as well as that of integrated HIV-1 proviruses in latent reservoirs without significant cytotoxicity.

The best of both: SIRT1/2 inhibitors were developed by combining chemical features of selisistat (SIRT1-selective inhibitor; blue) and carprofen (anti-inflammatory drug; red). The most potent compound (shown) increased acetyl-p53 and acetyl-α-tubulin levels, and induced slight apoptosis at 50 μM in U937 cells, differently from selisistat and carprofen.

The single enantiomers of two pyrimidine-based HIV-1 non-nucleoside reverse transcriptase inhibitors, 1 (MC1501) and 2 (MC2082), were tested in both cellular and enzyme assays. In general, the R forms were more potent than their S counterparts and racemates and (R)-2 was more efficient than (R)-1 and the reference compounds, with some exceptions. Interestingly, (R)-2 displayed a faster binding to K103N RT with respect to WT RT, while (R)-1 showed the opposite behavior.

An enhanced version of comparative binding energy (COMBINE) analysis, named COMBINEr, based on both ligand-based and structure-based alignments has been used to build several 3-D QSAR models for the eleven human zinc-based histone deacetylases (HDACs). When faced with an abundance of data from diverse structure-activity sources, choosing the best paradigm for an integrative analysis is difficult. A common example from studies on enzyme-inhibitors is the abundance of crystal structures characterized by diverse ligands complexed with different enzyme isoforms. A novel comprehensive tool for data mining on such inhomogeneous set of structure-activity data was developed based on the original approach of Ortiz, Gago, and Wade, and applied to predict HDAC inhibitors' isoform selectivity. The COMBINEr approach (apart from the AMBER programs) has been developed to use only software freely available to academics.

Chemical manipulations undertaken on some bis(bromo- and dibromo-phenol) compounds previously reported by us as wide-spectrum epigenetic inhibitors let us to identify bis (bromo- and dibromo-methoxyphenyl) derivatives highly selective for PR-SET7 and EZH2 (compounds 4, 5, 9, and 10). Western blot analyses were carried out in U937 cells to determine the effects of such compounds on the methyl marks related to the tested enzymes (H3K4me1, H3K9me2, H4H20me1, and H3K27me3). The 1,5-bis(3-bromo-4-methoxyphenyl)penta-1,4-dien-3- one 4 (EC50 vs EZH2 = 74.9 μM), tested in U937 cells at 50 μM, induced massive cell death and 28% of granulocytic differentiation, highlighting the potential use of EZH2 inhibitors in cancer. © 2012 Elsevier Masson SAS. All rights reserved.

Herein we reported two novel series of histone deacetylase inhibitors bearing the pyridine-2,6-dicarboxylate moiety as a zinc binding group. Tested on U937 leukemia cell line at 50 μM, compounds 4a, 4c and 4d showed cell cycle block in the S phase and apoptotic induction up to 50%, whereas compound 6h was able to give granulocytic differentiation up to 40%. From these results, the chelidamic scaffold will be further investigated to find more potent compounds. © 2012 The Royal Society of Chemistry.

The review describes the flourishing synthesis and brief structure-anti-HIV-1 activity relationships of 6-(arylmethyl)pyrimidin-4(3H)-one derivatives.

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Objective— To address the role of epigenetic enzymes in the process of arterial vasorelaxation and nitrate tolerance, in vitro and in vivo experiments were performed in the presence or absence of glyceryl trinitrate (GTN) or histone deacetylases/histone acetylases modulators. Methods and Results— In vitro single GTN administration rapidly increased cGMP synthesis and protein N ε -lysine acetylation in rat smooth muscle cells, including myosin light chain and smooth muscle actin. This phenomenon determined a decrease in myosin light chain phosphorylation and actomyosin formation. These effects were abolished by prolonged exposure to GTN and rescued by treatment with trichostatin A. In vivo, adult male rats were treated for 72 hours with subcutaneous injections of GTN alone or in combination with the histone deacetylases inhibitors trichostatin A, suberoylanilide hydroxamic acid, MS-27–275, or valproic acid. Ex vivo experiments performed on aortic rings showed that the effect of tolerance was reversed by all proacetylation drugs, including the p300/CREB binding protein–associated factor activator pentadecylidenemalonate 1b (SPV106). Any response to GTN was abolished by anacardic acid, a potent histone acetylases inhibitor. Conclusion— This study establishes the following points: (1) GTN treatment increases histone acetylases activity; (2) GTN–activated p300/CREB binding protein–associated factor increases protein N ε -lysine acetylation; (3) N ε -lysine acetylation of contractile proteins influences GTN–dependent vascular response. Hence, combination of epigenetic drugs and nitroglycerin may be envisaged as a novel treatment strategy for coronary artery disease symptoms and other cardiovascular accidents of ischemic origin.

Inhibition of sirtuins has recently been proposed as a promising anticancer strategy. Some of the new benzodeazaoxaflavins (2a, 2b, and 2d) here reported as SIRT1/2 inhibitors were endowed with pro-apoptotic properties in human U937 leukemia cells and, most importantly, together with the prototype MC2141 (1) displayed antiproliferative effects in cancer stem cells from patients with colorectal carcinoma and glioblastoma multiforme, known to be highly tumorigenic, resistant to conventional cancer chemotherapy, and responsible, at least in part, for cancer relapse or recurrence. © 2012 American Chemical Society.

Suberoylanilide hydroxamic acid (vorinostat) was the first of the histone deacetylase inhibitors (HDACi) to be entered as therapy for the treatment of cutaneous T-cell lymphoma. Since then, a number of HDACi belonging to the short-chain fatty acid, hydroxamate, cyclic peptide or benzamide classes have been investigated in Phase II or III clinical trials (alone or in combination) for the treatment of many kinds of tumors. In addition, HDACi can be useful in antimalarial and antifungal therapies, and can reactivate HIV-1 expression in latent cellular reservoirs, thus suggesting that they could be used in combination with highly active antiretroviral therapy. Moreover, they have also proved their efficacy in neurodegenerative diseases, such as Huntington’s disease, Parkinson’s disease and Friedreich’s ataxia. In particular, a new series of bis-anilides demonstrating a peculiar mechanism of action displayed highly beneficial effects against Huntington’s disease and Friedreich’s ataxia. In addition, a number of sirtuin inhibitors demonstrated antiproliferative effects in cell assays as well as in mouse tumor models, thus suggesting a role of such compounds in therapy against cancer. Furthermore, the SIRT2-selective AGK-2 has been reported to have protective effects against Parkinson’s disease, and resveratrol and other sirtuin activators can be useful for the treatment of Alzheimer’s disease.

The authors wish to add the following funding source to the financial disclosure information: "E.C. is recipient of the "Teresa Ariaudo Fellowship" from Istituto Pasteur-Fondazione Cenci Bolognetti".

International audience; Coactivator-associated arginine methyltransferase 1 (CARM1) represents a valuable target for hormone-dependent tumors such as prostate and breast cancers. Here we report the enzyme and cellular characterization of the 1-benzyl-3,5-bis(3-bromo-4-hydroxybenzylidene)piperidin-4-one (7g) and its analogues 8a-l. Among them, 7g, 8e, and 8l displayed high and selective CARM1 inhibition, with lower or no activity against a panel of different PRMTs or HKMTs. In human LNCaP cells, 7g showed a significant dose-dependent reduction of the PSA promoter activity.

Ovarian cancer frequently acquires resistance to platinum chemotherapy, representing a major challenge for improving patient survival. Recent work suggests that resistant clones exist within a larger drug-sensitive cell population prior to chemotherapy, implying that resistance is selected for rather than generated by treatment. We sought to compare clinically derived, intrapatient paired models of initial platinum response and subsequent resistant relapse to define molecular determinants of evolved resistance. Transcriptional analysis of a matched cell line series from three patients with high-grade serous ovarian cancer before and after development of clinical platinum resistance (PEO1/PEO4/PEO6, PEA1/PEA2, PEO14/PEO23) identified 91 up- and 126 downregulated genes common to acquired resistance. Significantly enhanced apoptotic response to platinum treatment in resistant cells was observed following knockdown of histone deacetylase (HDAC) 4, FOLR2, PIK3R1, or STAT1 (P < 0.05). Interestingly, HDAC4 and STAT1 were found to physically interact. Acetyl-STAT1 was detected in platinum-sensitive cells but not in HDAC4 overexpressing platinum-resistant cells from the same patient. In resistant cells, STAT1 phosphorylation/nuclear translocation was seen following platinum exposure, whereas silencing of HDAC4 increased acetyl-STAT1 levels, prevented platinum-induced STAT1 activation, and restored cisplatin sensitivity. Conversely, matched sensitive cells were refractory to STAT1 phosphorylation on platinum treatment. Analysis of 16 paired tumor biopsies taken before and after development of clinical platinum resistance showed significantly increased HDAC4 expression in resistant tumors [n = 7 of 16 (44%); P = 0.04]. Therefore, clinical selection of HDAC4-overexpressing tumor cells upon exposure to chemotherapy promotes STAT1 deacetylation and cancer cell survival. Together, our findings identify HDAC4 as a novel, therapeutically tractable target to counter platinum resistance in ovarian cancer. Cancer Res; 71(13); 4412–22. ©2011 AACR.

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.

Wanting to explore the epigenetic basis of Duchenne cardiomyopathy, we found that global histone acetylase activity was abnormally elevated and the acetylase P300/CBP-associated factor (PCAF) coimmunoprecipitated with connexin 43 (Cx43), which was N ε -lysine acetylated and lateralized in mdx heart. This observation was paralleled by Cx43 dissociation from N -cadherin and zonula occludens 1, whereas pp60-c-Src association was unaltered. In vivo treatment of mdx with the pan-histone acetylase inhibitor anacardic acid significantly reduced Cx43 N ε -lysine acetylation and restored its association to GAP junctions (GJs) at intercalated discs. Noteworthy, in normal as well as mdx mice, the class IIa histone deacetylases 4 and 5 constitutively colocalized with Cx43 either at GJs or in the lateralized compartments. The class I histone deacetylase 3 was also part of the complex. Treatment of normal controls with the histone deacetylase pan-inhibitor suberoylanilide hydroxamic acid (MC1568) or the class IIa-selective inhibitor 3-{4-[3-(3-fluorophenyl)-3-oxo-1-propen-1-yl]-1-methyl-1H-pyrrol-2-yl}-N-hydroxy-2-propenamide (MC1568) determined Cx43 hyperacetylation, dissociation from GJs, and distribution along the long axis of ventricular cardiomyocytes. Consistently, the histone acetylase activator pentadecylidenemalonate 1b (SPV106) hyperacetylated cardiac proteins, including Cx43, which assumed a lateralized position that partly reproduced the dystrophic phenotype. In the presence of suberoylanilide hydroxamic acid, cell to cell permeability was significantly diminished, which is in agreement with a Cx43 close conformation in the consequence of hyperacetylation. Additional experiments, performed with Cx43 acetylation mutants, revealed, for the acetylated form of the molecule, a significant reduction in plasma membrane localization and a tendency to nuclear accumulation. These results suggest that Cx43 N ε -lysine acetylation may have physiopathological consequences for cell to cell coupling and cardiac function.

Background Endothelial barrier dysfunction (EBD) involves microtubule disassembly and enhanced cell contractility. Histone deacetylase 6 (HDAC6) deacetylates α-tubulin, and thereby destabilizes microtubules. This study investigates a role for HDAC6 in EBD. Methods EBD was induced with thrombin ± HDAC6 inhibitors (tubacin and MC1575), and assessed by transendothelial electrical resistance (TEER). Markers for microtubule disassembly (α-tubulin and acetylated α-tubulin) and contraction (phosphorylated myosin light chain 2, P-MLC2) were measured using immunoblots and immunofluorescence. Results and conclusion Thrombin induced a ∼50% decrease in TEER that was abrogated by the HDAC6 inhibitors. Moreover, inhibition of HDAC6 diminished edema in the lung injured by lipopolysaccharide. Lastly, inhibition of HDAC6 attenuated thrombin-induced microtubule disassembly and P-MLC2. Our results suggest that HDAC6 can be targeted to limit EBD.

NAD+-dependent lysine deacetylases (sirtuins, SIRT1-7) have emerged as potential therapeutic targets for treatment of human illnesses such as cancer, metabolic, cardiovascular and neurodegenerative diseases. Sirtuins possess deacetylase and/or mono-ADP-ribosyltransferase activity, and this activity is directed to histone as well as non-histone targets involved in transcription, metabolism, and energy homeostasis [1,2]. SIRT1, having in cells a nuclear localization, has been widely recognized to play a multifaceted, protective role in aging, metabolism, and neurodegeneration [3]. In cancer, the role of SIRT1 is highly debated. Among SIRT1/2 inhibitors, sirtinol induced senescence-like growth arrest in human breast cancer MCF-7 cells and lung cancer H1299 cells [4] and inhibited cell growth in prostate cancer [5]; cambinol induced apoptosis in BCL6-expressing Burkitt lymphoma cells [6]; salermide was well tolerated by mice at concentrations up to 100 μM and prompted tumor-specific apoptosis in a wide range of human cancer cell lines [7]; MC2141 displayed high antiproliferative activity against Raji, DLD1, and HeLa cells [8], and tenovins, identified via a yeast genetic screen for p53 activators, decreased tumor growth in vivo as single agents at low micromolar concentrations [9]. On the other hand, in some contexts SIRT1 seems to have a protective role in cancer, in particular in colon cancer. SIRT2 is a cytoplasm enzyme mainly known as α-tubulin deacetylase, highly involved in cell cycle regulation. SIRT2 crucially regulates the functions in the mitotic checkpoint elicited by mitotic stress, as well as cell death in response to DNA damage-inducing stress [10]. In addition, SIRT2 influences adipocyte differentiation by deacetylation of FOXO proteins. Despite early evidences suggested SIRT1 as the main sirtuin target to inhibit for obtaining anticancer properties, recently SIRT2 down-regulation has been described to lead to apoptosis without cell cycle arrest in HeLa cells [11]. SIRT3-5 are mithocondrial deacetylases or ADP-ribosylases (SIRT4), and control adaptive thermogenesis (SIRT3), aging (SIRT3), insulin secretion (SIRT4), and ammonia detoxification (SIRT5) [1]. Finally, SIRT6 and SIRT7 are two nuclear and nucleolar enzymes, the first involved in the control of genomic DNA stability and DNA repair as well as glucose homeostasis, the latter exerting antiapoptotic properties [1]. In this month issue of AGING, Schlicker et al. described the identification of specific and semi-specific SIRT inhibitors through virtual screening performed by docking 1990 structurally different compounds into the peptide binding pockets of crystal structures of SIRT2, −3, −5, and −6. To avoid to select compounds blocking the NAD+ binding site, that is common to all the sirtuins and could highlight non isoform-specific compounds, the four SIRTs/NAD+ complexes have been used. For each docking run, the 10 top-ranking compounds have been selected and tested against SIRT2, −3, −5, and −6. Among the 20 compounds found active, 14 were selective for SIRT2, and 6 were able to inhibit, in addition to SIRT2, one (3 compounds) or two (2 compounds) or all (1 compound) of the other tested sirtuins. Interestingly, some compounds behaved as SIRT5 and/or SIRT6 activators. Two selected SIRT2-specific inhibitors, CSC8 and CSC13, bearing a steroid scaffold were selected for further studies. Dose-response curves gave IC50 values against SIRT2 of 4.8 (CSC8) and 9.7 (CSC13) μM. Tested against SIRT1, the two compounds showed weak inhibition at 100 μM. In functional tests in HEK cells, CSC13 increased the acetyl-α-tubulin level at 100 μM, thus confirming its SIRT2 inhibition at a cellular level. Such compound in particular seems to be interesting for further development, since carrying a 2-phenylpyrimidine moiety fused to the tetracyclic gonane structure, it is not predicted to interact with nuclear receptors, and thus it should be devoid of steroid receptor-mediated side effects.

A novel class of KAT modulators (long chain alkylidenemalonates, LoCAMs) has been identified. Variations of the alkyl chain length can change the activity profile from inhibition of both KAT3A/KAT2B (as derivative 2a) to the peculiar profile of pentadecylidenemalonate 1b, the first activator/inhibitor of histone acetyltransferases. Together with the powerful apoptotic effect (particularly notable if considering that anacardic acid and other KAT inhibitors are not cell permeable) appoint them as valuable biological tools to understand the mechanisms of lysine acetyltransferases. (C) 2011 Elsevier Ltd. All rights reserved.

The transcriptional peroxisome proliferator-activated receptor γ (PPARγ) co-activator PGC-1α plays a central role in the regulation of cellular energy metabolism. Among the wide range of its activities, PGC-1α controls mitochondrial biogenesis and function and is one of the main factors involved in hormonal and nutrient regulation of hepatic gluconeogenesis. PGC-1α is present in a multiprotein complex, and its activity can also be modulated through epigenetic modifications. In particular, it is directly acetylated by the HAT enzyme general control nonderepressible 5 (GCN5), resulting in a transcriptionally inactive protein that relocalizes from promoter regions to nuclear foci, whereas it is deacetylated by SIRT1 at multiple lysine sites, with a subsequent increase in its activity leading to induction of liver gluconeogenic gene transcription. Thus, both GCN5 and SIRT1 may be pharmacological targets to regulate the activity of PGC-1α, providing a potential treatment for metabolic disorders in which hepatic glucose output is altered.

The XendoU family of enzymes includes several proteins displaying high sequence homology. The members characterized so far are endoribonucleases sharing similar biochemical properties and a common architecture in their active sites. Despite their similarities, these proteins are involved in distinct RNA‐processing pathways in different organisms. The amphibian XendoU participates in the biosynthesis of small nucleolar RNAs, the human PP11 is supposed to play specialized roles in placental tissue, and NendoU has critical function in coronavirus replication. Notably, XendoU family members have been implicated in human pathologies such as cancer and respiratory diseases: PP11 is aberrantly expressed in various tumors, while NendoU activity has been associated with respiratory infections by pathogenic coronaviruses. The present study is aimed at identifying small molecules that may selectively interfere with these enzymatic activities. Combining structure‐based virtual screening and experimental approaches, we identified four molecules that specifically inhibited the catalytic activity of XendoU and PP11 in the low micromolar range. Moreover, docking experiments strongly suggested that these compounds might also bind to the active site of NendoU, thus impairing the catalytic activity essential for the coronavirus life cycle. The identified compounds, while allowing deep investigation of the molecular functions of this enzyme family, may also represent leads for the development of new therapeutic tools., Dock, dock, docking! Using a combination of structure‐based and experimental approaches, we identified four inhibitors of the catalytic activity of XendoU RNases, a family of enzymes implicated in a range of diseases. A pharmacophore model is proposed, highlighting the chemical properties potentially required for efficient binding to XendoU.WILEY-VCHThis article is being made freely available through PubMed Central as part of the COVID-19 public health emergency response. It can be used for unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original source, for the duration of the public health emergency.

Recently, many effortswere dedicated to the development of new highly selectiveand less toxic PARP-1 inhibitors. Most of these compounds actas competitive inhibitors by blocking the active site of theenzyme, although some benzamides have also been shown tohave additional effects, such as inhibition of the binding ofPARP-1 to DNA.

A series of 5-alkyl-2-(alkylthio)-6-(1-(2,6-difluorophenyl)propyl)-3,4-dihydropyrimidin-4(3H)-one derivatives (3a-h) belonging to the F(2)-DABOs class of non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs) are endowed with a strong antiproliferative effect and induce cytodifferentiation in A375 melanoma cells. Among tested compounds, the most potent is 3g (SPV122), which also induces apoptosis in a cell-density-dependent manner and antagonizes tumor growth in animal models. All these effects are similar or even more pronounced than those previously reported for other nucleoside or non-nucleoside inhibitors of reverse transcriptase or by functional knockout of the reverse-transcriptase-encoding long interspersed element 1 by RNA interference (RNAi). Taken together with our previously reported results, these data further confirm our idea that cellular alterations induced by NNRTIs are a consequence of the inhibition of the endogenous reverse transcriptase in A375 cells and support the potential of NNRTIs as valuable agents in cancer therapy.

In this work, we report on the difference in performance of the two 3 μm particle-based Chiralpak IA-3 and Chiralpak AD-3 chiral stationary phases (CSPs) in the direct resolution of four racemic cinnamyl 2-aminoanilides, endowed with histone deacetylase inhibitory activity. The 3 μm CSPs were explored to determine if they could provide an effective resolution of enantiomers in presence of alcoholic eluents such as pure methanol, ethanol and 2-propanol. Temperature variable enantioselective HPLC and subsequent van’t Hoff analysis were performed. In most of cases the van’t Hoff plots were found to show a non-linear behaviour. The knowledge of the enantiomeric elution order associated with the data coming from enantioselective HPLC permitted to advance some hypothesis about the groups involved in chiral recognition mechanism.

Histone deacetylase (HDAC) inhibitors are a new class of epigenetic agents that were reported to enhance the cytotoxic effects of classical anticancer drugs through multiple mechanisms. However, which of the possible drug combinations would be the most effective and clinically useful are to be determined. We treated the HL60 and NB4 promyelocytic leukaemia cells with a combination of the ribonucleotide reductase (RR) inhibitor 3'-C-methyladenosine (3'-Me-Ado) and several hydroxamic acid-derived HDAC inhibitors, including two recently synthesized molecules, MC1864 and MC1879, and the reference compound trichostatin A (TSA). The results showed significant growth inhibitory and apoptotic synergistic effects with the combinations. Hence, we evaluated the effects of the combinations on cell cycle distribution and on the level of several proteins involved in the apoptotic process (p21, caspase-3, Bcl-2, Bax, AIF). Since HDAC inhibitors increased the G1-S transition block induced by 3'-Me-Ado, an effect on RR activity was hypothesized. Indeed, the HPLC evaluation of intracellular deoxyribonucleotide (dNTP) pools showed that both TSA and MC1864 induced a decrease in dNTPs, even if with a somewhat different pattern, suggesting that RR inhibition contributes to the observed synergism. Furthermore, while TSA was shown to activate the intrinsic apoptotic pathway, MC1864 induced a dose-dependent increase in ROS and AIF levels. Moreover, the treatment with the radical scavenger N-acetylcysteine determined a significant inhibition of MC1864- but not TSA-mediated synergistic effects. Hence, our findings are consistent with a possible role of HDAC inhibitor mediated-ROS induction in RR inhibition and in the potentiation of RR inhibitor-mediated apoptosis.

Photoactivated cross-linking of peptides to proteins is a useful strategy for identifying enzyme-substrate and protein-protein interactions in cell lysates as demonstrated by studies on the human hypoxia inducible factor system.

Hydroxamic acids take their biological properties from the ability to chelate metal ions which are important for a variety of biological processes, as well as for the catalytic activity of a number of metalloenzymes. In particular, the preference for chelation of iron and zinc ions by hydroxamates led to derivatives endowed with high potential as therapeutic agents. As iron chelators, most hydroxamates and retro-hydroxamates (zileuton, atreleuton) are potent 5-lipoxygenase inhibitors, useful for treatment of inflammatory diseases, asthma, and cancer, others (deferoxamine) can be used for the molecular control of iron homeostasis during transfusional iron overload, and for the treatment of acute ischemic stroke, thalassemia, and sickle cell anemia. Metal ion complexation by hydroxamates furnished also highly active antibacterial agents, through inhibition of two metal-containing enzymes (peptide deformylase with iron, and UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) with zinc) crucial for bacterial growth and viability. The ability of hydroxamates to efficiently complex zinc ion makes them useful compounds for inhibiting matrix metalloproteinases (MMPs) and related enzymes (see for example prinomastat) responsible for cancer and arthritis diseases, and histone deacetylases (HDACs), a family of enzymes involved in gene silencing and loss of tumor suppressor functions (see for example vorinostat and romidepsin, recently approved by FDA for the treatment of cutaneous T-cell lymphoma). Keywords: hydroxamic acids; metal ion chelation; 5-lipoxygenase inhibitors; iron chelators; peptide deformylase inhibitors; UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC) inhibitors; matrix metalloproteinases (MMPs) inhibitors; histone deacetylases (HDACs) inhibitors

The alkylation of 5-alkyl-6-(2,6-dihalobenzyl)-2-thioxo-2,3-dihydropyrimidin-4(1H)-ones with MeI, AllSCH2Cl, and MeSCH2Cl in the K2CO3–DMF, NaOMe–MeOH, and KOH–EtOH systems was investigated. A hypothetical mechanism for the reaction is examined, and an explanation is proposed for the composition of the reaction products. The presence of high anti-HIV-1 activity was established in the obtained derivatives of 2-{[(allylsulfanyl)methyl]sulfanyl}pyrimidin-4(3H)-one.

New tetracyclic systems containing a pyrrolobenzodiazepine 5 or a pyrrolobenzotriazepine 6 moiety bounded by a spiro linkage to the piperidine nucleus are described. They have been synthesized by a simple reaction involving the interaction between proper aromatic amines and 4-oxopiperidines substituted or not at the 1-position in the presence of maleic acid as a catalyst. The synthesis of spiropyrrolo[1,2-a]quinoxaline-2,4′-piperidine 7 and its 1′-acyl derivatives by the same procedure is also reported.

The synthesis of the novel tetracyclic rings 5 and 6 is described starting from 4-cyano-1-methyl-5(1H-pyrrol-1-yl)-1H-pyrazole and its 3-(1H-pyrrol-1-yl)- isomer, respectively. The pathway employed is based on a one-pot double annelation reaction involving the transformation of 13 into the required tetracyclic derivative 16. Lithium aluminum hydride/sulfuric acid reduction of the last compound furnished 5. A similar way was used for the synthesis of 6 by cyclization of 20.