HDAC Enzymes Research Articles

338 (PB326): Small-molecule bifunctional inhibitors of PARP1/2 and HDAC enzymes

338 (PB326): Small-molecule bifunctional inhibitors of PARP1/2 and HDAC enzymes

In Silico Prediction of Binding Affinities of Hybrid Molecules of Benzothiazole Linked with Hydroxamic Acid by Disulfide Bond and Certain Linkers with HDAC8 Enzyme

A new hybrid molecule of Benzothiazole cross-linked with hydroxamic acid through an amino acid or aminoalkanoic acid were synthesised. All the synthesized hybrid molecules (1-5) were subjected to molecular docking studies to evaluate their binding affinities with histone deacetylase enzyme (HDAC8, PDB ID: 1T69) and recorded lower ΔG (-8.276, -10.093, -8.647, -6.315, -8.676 kcal/mole, respectively) than the reference ligand (Vorinostat, suberoylanilide hydroxamic acid, SAHA -5.375 kcal/mole). Molecular docking studies were performed using the maestro software (Schrödinger, version 2022-1). Moreover, compound 2, which is Benzothiazole-p-amino benzoic acid-hydroxamate has recorded the lowest binding score (-10.093). This may indicate that this compound is the most potent hybrid molecule. There were no violations from Lipinski’s rule and all the synthesized hybrid molecules comply with all parameters. Swiss ADME server was employed for the in silico molecular docking for prediction of the physicochemical and ADME properties of the investigated compounds. All hybrid molecules showed low possible passive oral absorption and no penetration into BBB. The hybrid molecules 1and 3 may be considered as P-gp substrates.

Entinostat, a class I selective histone deacetylase inhibitor, plus exemestane for Chinese patients with hormone receptor-positive advanced breast cancer: An overall survival update and long-term safety from the randomised, double-blind, placebo-controlled, phase 3 trial.

1050 Background: Entinostat, a synthetic benzamide derivative HDAC inhibitor, selectively targets Class I HDAC enzymes. In a randomized, double-blind, phase 3 trial, entinostat with exemestane demonstrated a statistically significant progression-free survival (PFS) benefit compared to placebo, with a median PFS of 6.32 months versus 3.72 months (HR 0.76, 95% CI 0.58-0.98, p=0.046; Binghe Xu, et al. Acta Pharm Sin B. 2023). This analysis focus on the results of overall survival (OS) and long-term safety. Methods: Patients eligible for this study had HR+/HER2– advanced breast cancer (ABC) with disease relapse or progression following at least one prior endocrine therapy (ET). They were randomly assigned in a 2:1 ratio to receive either entinostat (5mg, weekly) or placebo in combination with exemestane until disease progression or unacceptable toxicity. The primary endpoint of the study was PFS. Secondary endpoints included OS, objective response rate, clinical benefit rate and safety. Median OS was estimated using the Kaplan-Meier method and the HR and its 95% CI were calculated using the multivariate Cox proportional hazard regression model. Results: A total of 354 patients were randomized to receive either entinostat (n=235) or placebo (n=119). As of the data cutoff date (July 31, 2023), 196 (55.4%) OS events had occurred, with a median follow-up of 31.83 months. There were 127 (54.0%) deaths in the entinostat arm compared to 69 (58.0%) deaths in the placebo arm. The entinostat demonstrated improved OS compared to placebo, with a median OS of 38.39 months versus 29.18 months (HR 0.837, 95% CI 0.624-1.124, p=0.237) in the full analysis set (FAS). The results of the per-protocol analysis set (PPS) were consistent with those of the FAS, showing a median OS of 39.01 months versus 33.98 months (HR 0.796, 95% CI 0.588-1.079, p=0.142). Notably, 179 (76.2%) patients in the entinostat arm and 100 (84%) patients in the placebo arm received new anti-cancer regimens, including CDK4/6 inhibitors (14.5% vs 24.4%), chemotherapy (54.9% vs 63.9%), endocrine therapy (40.4% vs 42.9%), and herbal medicines (9.8% vs 3.4%). After adjusting for the imbalance in the use of CDK4/6 inhibitors and chemotherapy between the treatment arms, the HR for overall survival was 0.78 (95% CI 0.58-1.05, p=0.097). The updated safety results were generally consistent with the previous analysis. Conclusions: The combination of entinostat with exemestane has provided clinically meaningful OS benefit in addition to the previously observed PFS benefit over exemestane alone in patients with pre-treated, ET-resistant ABC. These findings further support entinostat as an effective and safe treatment option for the specific patient population. Clinical trial information: NCT03538171 .

Design and Structural Investigation of a Series of Prodigiosin and 1,10-Phenanthroline Derivatives as Novel and Highly Potent Anticancer Therapeutic Drugs or Active Pharmaceutical Ingredients

Breast cancer is considered as a leading cancer type with the secondary highest possibility of brain metastasis. Most research in breast cancer is currently directed into the mortality of brain metastatic breast cancer. However, there is no effective treatment or anticancer therapeutics specifically for this cancer type. Hence, development of effective and novel anticancer therapeutic drugs/APIs to inhibit HDAC and mTOR, playing very important role on modulating breast cancer progression is an increasing demand. In this study, the structure-activity relationship and in silico modeling of a series of prodigiosin and 1,10-phenanthroline derivatives as highly potent anticancer therapeutic drugs/APIs against mTOR and HDAC enzymes have been investigated. Compared to the natural product Ps, 20 of the highly potent ligands, especially 2a, 6b, 13 and 13a, have exhibited very promising binding energies ranging from –9.4 to –7.1 kcal/mol and inhibition constants ranging from 225 to 569 nM against HDAC1 and/or mTOR enzymes. Ligands 2a, 5, 6b, 7b and 13 in particular show effective dual action against both enzymes. The findings from the in silico modeling studies have also been supported with MD simulations and ADMET study with Lipinski’s rule of five, providing outstanding therapeutic potential for the breast cancer brain metastasis.

Design and evaluation of nanoscale materials with programmed responsivity towards epigenetic enzymes.

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly(acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. The hydrodynamic diameters of particles were typically withing the range of 108-190 nm, depending on degree of acetylation of the hydrophobic block. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We also demonstrated the biocompatibility and cellular effects of these materials in the context of drug delivery in different types of anticancer cell lines, such as MIA PaCa-2, PANC-1, cancer like stem cells (CSCs), and non-cancerous HPNE cells. We observed that the release of a model drug (such as a STAT3 pathway inhibitor, Napabucasin) can be loaded into these nanoparticles, with >90% of the dosage can be released over 3 h under the influence of HDAC8 enzyme in a controlled fashion. Further, we conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Inhibition of PI3K-AKT-mTOR pathway and modulation of histone deacetylase enzymes reduce the growth of acute myeloid leukemia cells.

One of the most widespread forms of blood cancer is known as acute myeloid leukemia (AML) which has an incidence of 80% with poor prognosis. Although there are different treatment methods for AML in clinic, the heterogeneity and complexity of the disease show that new treatments are needed. The aim of this study is to investigate the anticancer effects of inhibition of PI3K and HDAC enzymes on CMK and MOLM-13 AML cells lines. We demonstrated that the combination of LY294002 with SAHA and Tubastatin A significantly decreased the cell viability of both cell lines. In contrast, the LY294002 and PCI-34051 combination did not show a significant difference compared to the single LY294002 administration. The combination treatment of LY294002 and HDAC inhibitors did not induce apoptosis significantly. However, LY294002 + SAHA and LY294002 + PCI-34051 resulted in G0/G1 and G2/M cell cycle arrest in CMK cells, respectively. On the other hand, compared to control cells, LY294002 + SAHA and LY294002 + PCI-34051 led to G0/G1 phase arrest in MOLM-13. Furthermore, the LY294002 + PCI-34051 combination elevated the expression rate of LC3BII/I, an autophagy marker, in CMK cells by 2.5-fold. Our study revealed that the combinations of PI3K inhibitor and HDAC inhibitors showed a synergistic effect and caused a reduction in cell viability and increased cell cycle arrest on MOLM-13 and CMK cell lines. In addition, the expression of LC3BII was elevated in the CMK cell line. In conclusion, although more mechanistic studies are required, a combinational inhibition of PI3K and HDAC could be a promising approach for AML.

MDM2 Antagonist Idasanutlin Reduces HDAC1/2 Abundance and Corepressor Partners but Not HDAC3.

Histone deacetylases 1-3 (HDAC1, HDAC2, and HDAC3) and their associated corepressor complexes play important roles in regulating chromatin structure and gene transcription. HDAC enzymes are also validated drug targets for oncology and offer promise toward new drugs for neurodegenerative diseases and cardiovascular diseases. We synthesized four novel heterobifunctional molecules designed to recruit the mouse double minute 2 homologue (MDM2) E3 ligase to degrade HDAC1-3 utilizing the MDM2 inhibitor idasanutlin, known as proteolysis targeting chimeras (PROTACs). Idasanutlin inhibits the MDM2-P53 protein-protein interaction and is in clinical trials. Although two MDM2-recruiting heterobifunctional molecules reduced HDAC1 and HDAC2 abundance with complete selectivity over HDAC3 and reduced HDAC1/2 corepressor components LSD1 and SIN3A, we were surprised to observe that idasanutlin alone was also capable of this effect. This finding suggests an association between the MDM2 E3 ligase and HDAC1/2 corepressor complexes, which could be important for designing future dual/bifunctional HDAC- and MDM2-targeting therapeutics, such as PROTACs.

Intrinsic structural dynamics dictate enzymatic activity and inhibition

Enzymes are known to sample various conformations, many of which are critical for their biological function. However, structural characterizations of enzymes predominantly focus on the most populated conformation. As a result, single-point mutations often produce structures that are similar or essentially identical to those of the wild-type enzyme despite large changes in enzymatic activity. Here, we show for mutants of a histone deacetylase enzyme (HDAC8) that reduced enzymatic activities, reduced inhibitor affinities, and reduced residence times are all captured by the rate constants between intrinsically sampled conformations that, in turn, can be obtained independently by solution NMR spectroscopy. Thus, for the HDAC8 enzyme, the dynamic sampling of conformations dictates both enzymatic activity and inhibitor potency. Our analysis also dissects the functional role of the conformations sampled, where specific conformations distinct from those in available structures are responsible for substrate and inhibitor binding, catalysis, and product dissociation. Precise structures alone often do not adequately explain the effect of missense mutations on enzymatic activity and drug potency. Our findings not only assign functional roles to several conformational states of HDAC8 but they also underscore the paramount role of dynamics, which will have general implications for characterizing missense mutations and designing inhibitors.

Evolution of Slow-Binding Inhibitors Targeting Histone Deacetylase Isoforms.

Because the overexpression of histone deacetylase enzymes (HDACs) has been linked to numerous diseases, including various cancers and neurodegenerative disorders, HDAC inhibitors have emerged as promising therapeutic agents. However, most HDAC inhibitors lack both subclass and isoform selectivity, which leads to potential toxicity. Unlike classical hydroxamate HDAC inhibitors, slow-binding HDAC inhibitors form tight and prolonged bonds with HDAC enzymes. This distinct mechanism of action improves both selectivity and toxicity profiles, which makes slow-binding HDAC inhibitors a promising class of therapeutic agents for various diseases. Therefore, the development of slow-binding HDAC inhibitors that can effectively target a wide range of HDAC isoforms is crucial. This Perspective provides valuable insights into the potential and progress of slow-binding HDAC inhibitors as promising drug candidates for the treatment of various diseases.

Docking Study, Synthesis, Characterization and Preliminary Cytotoxic Evaluation of New 1,3,4- Thiadiazole Derivatives

Objectives: This study has determined that these newly synthesized analogs hold promise as potential sources of novel anticancer agents for combating breast cancer.
 Methods: We initiated our research by obtaining the crystal structure of Histone deacetylases (HDACs-8) bound with Vorinostat (SAHA) from the Protein Data Bank (PDB code 4QA0). Subsequently, we conducted docking experiments, which revealed that compounds (V c,s, V d,s, V c,t, and V d,t) exhibited favorable docking scores when compared to the standard. These compounds, synthesized through multi-step procedures involving the reaction of intermediate derivatives (IV c,d) with thiosemicarbazide or semicarbazide, were subjected to confirmation of their chemical structures using FT-IR and 1H NMR analysis.
 Results: The results of our in-vitro cytotoxicity assay (MTT assay) highlighted that compounds V c,t and V d,t exhibited notable inhibition ratios in the breast cancer cell line (MCF-7), while V c,t displayed similar efficacy in human colon adenocarcinoma (HRT-18) compared to the control drug, Vorinostat (SAHA).
 Conclusion: Our docking analysis led us to conclude that the C=S moiety demonstrated exceptional binding affinity to the zinc binding group of the HDAC enzyme, establishing multiple interaction modes. This finding suggests the potential of these compounds as valuable candidates in the development of anticancer treatments.

Characterization of K562 cells: uncovering novel chromosomes, assessing transferrin receptor expression, and probing pharmacological therapies.

Human erythroleukemic K562 cells represent the prototypical cell culture model of chronic myeloid leukemia (CML). The cells are pseudo-triploid and positive for the Philadelphia chromosome. Therefore, K562 cells have been widely used for investigating the BCR/ABL1 oncogene and the tyrosine kinase inhibitor, imatinib-mesylate. Further, K562 cells overexpress transferrin receptors (TfR) and have been used as a model for targeting cytotoxic therapies, via receptor-mediated endocytosis. Here, we have characterized K562 cells focusing on the karyotype of cells in prolonged culture, regulation of expression of TfR in wildtype (WT) and doxorubicin-resistant cells, and responses to histone deacetylase inhibition (HDACi). Karyotype analysis indicates novel chromosomes and gene expression analysis suggests a shift of cultured K562 cells away from patient-derived leukemic cells. We confirm the high expression of TfR on K562 cells using immunofluorescence and cell-surface receptor binding radioassays. Importantly, high TfR expression is observed in patient-derived cells, and we highlight the persistent expression of TfR following doxorubicin acquired resistance. Epigenetic analysis indicates that permissive histone acetylation and methylation at the promoter region regulates the transcription of TfR in K562 cells. Finally, we show relatively high expression of HDAC enzymes in K562 cells and demonstrate the chemotoxic effects of HDACi, using the FDA-approved hydroxamic acid, vorinostat. Together with a description of morphology, infrared spectral analysis, and examination of metabolic properties, we provide a comprehensive characterization of K562 cells. Overall, K562 cell culture systems remain widely used for the investigation of novel therapeutics for CML, which is particularly important in cases of imatinib-mesylate resistance.

HDAC1 and HDAC6 are essential for driving growth in IDH1 mutant glioma

Low-grade and secondary high-grade gliomas frequently contain mutations in the IDH1 or IDH2 metabolic enzymes that are hypothesized to drive tumorigenesis by inhibiting many of the chromatin-regulating enzymes that regulate DNA structure. Histone deacetylase inhibitors are promising anti-cancer agents and have already been used in clinical trials. However, a clear understanding of their mechanism or gene targets is lacking. In this study, the authors genetically dissect patient-derived IDH1 mutant cultures to determine which HDAC enzymes drive growth in IDH1 mutant gliomas. A panel of patient-derived gliomasphere cell lines (2 IDH1 mutant lines, 3 IDH1 wildtype lines) were subjected to a drug-screen of epigenetic modifying drugs from different epigenetic classes. The effect of LBH (panobinostat) on gene expression and chromatin structure was tested on patient-derived IDH1 mutant lines. The role of each of the highly expressed HDAC enzymes was molecularly dissected using lentiviral RNA interference knock-down vectors and a patient-derived IDH1 mutant in vitro model of glioblastoma (HK252). These results were then confirmed in an in vivo xenotransplant model (BT-142). The IDH1 mutation leads to gene down-regulation, DNA hypermethylation, increased DNA accessibility and H3K27 hypo-acetylation in two distinct IDH1 mutant over-expression models. The drug screen identified histone deacetylase inhibitors (HDACi) and panobinostat (LBH) more specifically as the most selective compounds to inhibit growth in IDH1 mutant glioma lines. Of the eleven annotated HDAC enzymes (HDAC1-11) only six are expressed in IDH1 mutant glioma tissue samples and patient-derived gliomasphere lines (HDAC1-4, HDAC6, and HDAC9). Lentiviral knock-down experiments revealed that HDAC1 and HDAC6 are the most consistently essential for growth both in vitro and in vivo and target very different gene modules. Knock-down of HDAC1 or HDAC6 in vivo led to a more circumscribed less invasive tumor. The gene dysregulation induced by the IDH1 mutation is wide-spread and only partially reversible by direct IDH1 inhibition. This study identifies HDAC1 and HDAC6 as important and drug-targetable enzymes that are necessary for growth and invasiveness in IDH1 mutant gliomas.

Identification of structural fingerprints among natural inhibitors of HDAC1 to accelerate nature-inspired drug discovery in cancer epigenetics

Histone deacetylase 1 (HDAC1), a class I HDAC enzyme, is crucial for histone modification. Currently, it is emerged as one of the important biological targets for designing small molecule drugs through cancer epigenetics. Along with synthetic inhibitors different natural inhibitors are showing potential HDAC1 inhibitions. In order to gain insights into the relationship between the molecular structures of the natural inhibitors and HDAC1, different molecular modelling techniques (Bayesian classification, recursive partitioning, molecular docking and molecular dynamics simulations) have been applied on a dataset of 155 HDAC1 nature-inspired inhibitors with diverse scaffolds. The Bayesian study showed acceptable ROC values for both the training set and test sets. The Recursive partitioning study produced decision tree 1 with 6 leaves. Further, molecular docking study was processed for generating the protein ligand complex which identified some potential amino acid residues such as F205, H28, L271, P29, F150, Y204 for the binding interactions in case of natural inhibitors. Stability of these HDAC1-natutal inhibitors complexes has been also evaluated by molecular dynamics simulation study. The current modelling study is an attempt to get a deep insight into the different important structural fingerprints among different natural compounds modulating HDAC1 inhibition. Communicated by Ramaswamy H. Sarma

Structural Basis of Sirtuin 6-Catalyzed Nucleosome Deacetylation.

The reversible acetylation of histone lysine residues is controlled by the action of acetyltransferases and deacetylases (HDACs), which regulate chromatin structure and gene expression. The sirtuins are a family of NAD-dependent HDAC enzymes, and one member, sirtuin 6 (Sirt6), influences DNA repair, transcription, and aging. Here, we demonstrate that Sirt6 is efficient at deacetylating several histone H3 acetylation sites, including its canonical site Lys9, in the context of nucleosomes but not free acetylated histone H3 protein substrates. By installing a chemical warhead at the Lys9 position of histone H3, we trap a catalytically poised Sirt6 in complex with a nucleosome and employ this in cryo-EM structural analysis. The structure of Sirt6 bound to a nucleosome reveals extensive interactions between distinct segments of Sirt6 and the H2A/H2B acidic patch and nucleosomal DNA, which accounts for the rapid deacetylation of nucleosomal H3 sites and the disfavoring of histone H2B acetylation sites. These findings provide a new framework for understanding how HDACs target and regulate chromatin.

Introducing HDAC-Targeting Radiopharmaceuticals for Glioblastoma Imaging and Therapy.

Despite recent advances in multimodality therapy for glioblastoma (GB) incorporating surgery, radiotherapy, chemotherapy and targeted therapy, the overall prognosis remains poor. One of the interesting targets for GB therapy is the histone deacetylase family (HDAC). Due to their pleiotropic effects on, e.g., DNA repair, cell proliferation, differentiation, apoptosis and cell cycle, HDAC inhibitors have gained a lot of attention in the last decade as anti-cancer agents. Despite their known underlying mechanism, their therapeutic activity is not well-defined. In this review, an extensive overview is given of the current status of HDAC inhibitors for GB therapy, followed by an overview of current HDAC-targeting radiopharmaceuticals. Imaging HDAC expression or activity could provide key insights regarding the role of HDAC enzymes in gliomagenesis, thus identifying patients likely to benefit from HDACi-targeted therapy.

Salivary histone deacetylase in periodontal disease: A cross-sectional pilot study.

The objective of the study was to profile the expression level of histone deacetylase enzymes (HDACs) in human saliva in periodontal health, gingivitis and periodontitis. HDACs are epigenetic modulators and a group of enzymes that catalyse the removal of acetyl functional groups from the lysine residues of both histone and nonhistone proteins. HDACs have been detected in gingival tissues and may provide valuable insight into the periodontal inflammatory response. However, no studies have investigated the expression of HDACs in saliva from periodontitis-affected individuals and their capacity for periodontal diagnostics and screening. Whole unstimulated saliva was collected from 53 participants (17 healthy, 14 gingivitis and 22 stages III/IV periodontitis). The expression of 11 HDACs in saliva samples was determined using RT-qPCR and diagnostic power was calculated using the receiver operating characteristic (ROC) curves and area under the ROC Curve (AUC). Relative to health, the expression of HDAC4, 8 and 10 was downregulated in gingivitis, and the expression of HDAC4, 6, 8 and 9 was downregulated in periodontitis. Increased HDAC1 and decreased HDAC9 expression were observed in periodontitis compared to gingivitis. Higher HDAC1 and lower HDAC6 and 9 expression was observed in periodontitis compared to non-periodontitis (combining health and gingivitis). Expression of HDAC3, 4, 8, 9 and 10 was significantly decreased in periodontal disease (combining gingivitis and periodontitis) compared to health. HDAC4 and 8 exhibited an excellent diagnostic capacity for distinguishing gingivitis and periodontal disease from health (AUC 0.79-0.86). HDAC9 showed an acceptable power in discriminating periodontitis from health, gingivitis and non-periodontitis (AUC 0.76-0.80). Salivary HDAC enzyme activity showed no significant difference among the groups. This pilot study has demonstrated the differential expression of HDACs in human saliva for the first time and identified HDAC4, 8 and 9 as potential biomarkers in periodontal diagnosis.

Epigenetics Mechanisms of Honeybees: Secrets of Royal Jelly.

Early diets in honeybees have effects on epigenome with consequences on their phenotype. Depending on the early larval diet, either royal jelly (RJ) or royal worker, 2 different female castes are generated from identical genomes, a long-lived queen with fully developed ovaries and a short-lived functionally sterile worker. To generate these prominent physiological and morphological differences between queen and worker, honeybees utilize epigenetic mechanisms which are controlled by nutritional input. These mechanisms include DNA methylation and histone post-translational modifications, mainly histone acetylation. In honeybee larvae, DNA methylation and histone acetylation may be differentially altered by RJ. This diet has biologically active ingredients with inhibitory effects on the de novo methyltransferase DNMT3A or the histone deacetylase 3 HDAC3 to create and maintain the epigenetic state necessary for developing larvae to generate a queen. DNMT and HDAC enzymes work together to induce the formation of a compacted chromatin structure, repressing transcription. Such dialog could be coordinated by their association with other epigenetic factors including the ubiquitin-like containing plant homeodomain (PHD) and really interesting new gene (RING) finger domains 1 (UHRF1). Through its multiple functional domains, UHRF1 acts as an epigenetic reader of both DNA methylation patterns and histone marks. The present review discusses the epigenetic regulation of honeybee's chromatin and how the early diets in honeybees can affect the DNA/histone modifying types of machinery that are necessary to stimulate the larvae to turn into either queen or worker. The review also looks at future directions in epigenetics mechanisms of honeybees, mainly the potential role of UHRF1 in these mechanisms.

EXTH-30. PHARMACOKINETICS- AND PHARMACODYNAMICS-BASED EVALUATION OF QUISINOSTAT AS A RADIOSENSITIZER IN PRECLINICAL MODELS OF GBM

Abstract Glioblastoma (GBM) is characterized by an aberrant yet druggable epigenetic landscape. Class I HDACs mediate chromatin compaction and are frequently overexpressed in GBM. Hence, there has been considerable interest in HDAC inhibitors (HDACi) for the treatment of malignant brain tumors. However, to date almost all HDACi tested clinically have failed to provide significant therapeutic benefit to primary and recurrent GBM patients. These HDACi are broad-spectrum with poor or unknown pharmacokinetic profiles and narrow therapeutic window. Isoform specificity for HDACi is important given that not all HDAC enzymes are equally expressed in GBM. Recently, we uncovered the functional importance of HDAC1 in therapy-resistant glioma stem cells, where we found that its expression increases with brain tumor grade and is correlated with decreased survival. While no class I HDAC isoform-specific inhibitors are currently available, the second-generation HDACi quisinostat harbors high specificity for HDAC1. In this study, we assessed the pharmacokinetic, pharmacodynamic and radiation-sensitizing properties of quisinostat in preclinical models of human GBM. In vitro analyses conducted in patient-derived glioma stem cell (GSC) lines revealed that quisinostat exhibited potent growth inhibition, induced global histone hyperacetylation, elevated DNA damage, cell death and cell cycle arrest. To determine the efficacy and drug distribution profile of quisinostat in vivo, athymic mice with orthotopic or flank tumors were treated with an optimized treatment schedule. At various timepoints during treatment, plasma and brain/tumor tissue were collected to measure total and unbound drug levels by liquid chromatography tandem mass spectrometry (LC-MS/MS), coupled with transcriptomic and pharmacodynamic analyses of tumor tissues. We demonstrate quisinostat is a brain-penetrant molecule that reduces tumor burden in flank and orthotopic models of GBM, and significantly extends survival when administered with radiation. Together, these results provide a rationale for developing quisinostat as a potential combination therapy with radiation for the treatment of GBM.

Docking study, Synthesis, Characterization and Preliminary cytotoxic evaluation of new 1,2,3,4-tetrahydroppyrimidine derivatives

Objective: This study resolved that1 these anew synthesized analogs1 may 1be embodied as1 an 1exploitable foundation of new 1anticancer1 1agents to competition breast 1cancer
 Methods: By means of The crystal1 structure of Histone deacetylases (HDACs-8) with Vorinostat (SAHA) as 1a co-crystalized1 ligand 1was gained1 from 1the protein 1data-bank 1 (PDB 1code 4QA0) as a result 1of 1docking the compounds (V a,s, V b,s, V a,t and V b,t) give 1good docking 1scores compared1 to the standard. 1 Compounds (V a,s, V b,s, V a,t and V b,t) was synthesized1 by multistep procedures1 from the reaction of intermediate derivatives (IV a,b) and the thiosemicarbazide or semicarbazide . The chemical1 structures1 of the1 target compounds11 and 1their intermediates1 were1 confirmed by 1FT-IR and1H 1NMR
 Results: The in-vitro cytotoxicity1 assay (MTT assay) demonstrated1 that compounds1 V a,t and V b,t showed1 good inhibition 1ratios in Breast1 cancer cell line1 (MCF-7) and human colon adenocarcinoma (HRT-18) 1comparable with drug1 control Vorinostat (SAHA).
 Conclusion: 1From the docking1 study, it was1 concluded1 that C=S moiety were very1 1successful to bind 1tightly to the zinc binding group of HDAC enzyme by making numerous 1interaction modes.

Design, synthesis, molecular modeling, and bioactivity evaluation of 1,10-phenanthroline and prodigiosin (Ps) derivatives and their Copper(I) complexes against mTOR and HDAC enzymes as highly potent and effective new anticancer therapeutic drugs.

Breast cancer is the second type of cancer with a high probability of brain metastasis and has always been one of the main problems of breast cancer research due to the lack of effective treatment methods. Demand for developing an effective drug against breast cancer brain metastasis and finding molecular mechanisms that play a role in effective treatment are gradually increasing. However, there is no effective anticancer therapeutic drug or treatment method specific to breast cancer, in particular, for patients with a high risk of brain metastases. It is known that mTOR and HDAC enzymes play essential roles in the development of breast cancer brain metastasis. Therefore, it is vital to develop some new drugs and conduct studies toward the inhibition of these enzymes that might be a possible solution to treat breast cancer brain metastasis. In this study, a series of 1,10-phenanthroline and Prodigiosin derivatives consisting of their copper(I) complexes have been synthesized and characterized. Their biological activities were tested in vitro on six different cell lines (including the normal cell line). To obtain additional parallel validations of the experimental data, some in silico modeling studies were carried out with mTOR and HDAC1 enzymes, which are very crucial drug targets, to discover novel and potent drugs for breast cancer and related brain metastases disease.