Inhibition Of Histone Deacetylase Activity Research Articles

HDAC inhibitors activate lipid peroxidation and ferroptosis in gastric cancer

Gastric cancer remains among the deadliest neoplasms worldwide, with limited therapeutic options. Since efficacies of targeted therapies are unsatisfactory, drugs with broader mechanisms of action rather than a single oncogene inhibition are needed. Preclinical studies have identified histone deacetylases (HDAC) as potential therapeutic targets in gastric cancer. However, the mechanism(s) of action of HDAC inhibitors (HDACi) are only partially understood. This is particularly true with regard to ferroptosis as an emerging concept of cell death.In a panel of gastric cancer cell lines with different molecular characteristics, tumor cell inhibitory effects of different HDACi were studied. Lipid peroxidation levels were measured and proteome analysis was performed for the in-depth characterization of molecular alterations upon HDAC inhibition. HDACi effects on important ferroptosis genes were validated on the mRNA and protein level.Upon HDACi treatment, lipid peroxidation was found increased in all cell lines. Class I HDACi (VK1, entinostat) showed the same toxicity profile as the pan-HDACi vorinostat. Proteome analysis revealed significant and concordant alterations in the expression of proteins related to ferroptosis induction. Key enzymes like ACSL4, POR or SLC7A11 showed distinct alterations in their expression patterns, providing an explanation for the increased lipid peroxidation. Results were also confirmed in primary human gastric cancer tissue cultures as a relevant ex vivo model.We identify the induction of ferroptosis as new mechanism of action of class I HDACi in gastric cancer. Notably, these findings were independent of the genetic background of the cell lines, thus introducing HDAC inhibition as a more general therapeutic principle.

Evaluation of 1,10-phenanthroline-based hydroxamate derivative as dual histone deacetylases/ribonucleotide reductase inhibitor with antitumor activities.

Aberrant expression of histone deacetylases (HDACs) and ribonucleotide reductase (RR) enzymes are commonly observed in various cancers. Researchers are focusing on these enzymes in cancer studies with the aim of developing effective chemotherapeutic drugs for cancer treatment. Targeting both HDAC and RR simultaneously with a dual HDAC/RR inhibitor has exhibited enhanced effectiveness compared to monotherapy in cancer treatment, making it a promising strategy. The objective of the study is to synthesize and assess the anti-cancer properties of a 1,10-phenanthroline-based hydroxamate derivative, characterizing it as a novel dual HDAC/RR inhibitor. The N1-hydroxy-N8-(1,10-phenanthrolin-5-yl)octanediamide (PA), a 1,10-phenanthroline-based hydroxamate derivative, was synthesized and structurally characterized. The compound was subjected to in vitro assessments of its anti-cancer, HDAC, and RR inhibitory activities. In silico docking and molecular dynamics simulations were further studied to explore its interactions with HDACs and RRM2. The structurally confirmed PA exhibited antiproliferative activity in SiHa cells with an IC50 of 16.43μM. It displayed potent inhibitory activity against HDAC and RR with IC50 values of 10.80μM and 9.34μM, respectively. Co-inhibition of HDAC and RR resulted in apoptosis-induced cell death in SiHa cells, mediated by the accumulation of reactive oxygen species (ROS). In silico docking studies demonstrated that PA can effectively bind to the active sites of HDAC isoforms and RRM2. Furthermore, PA demonstrated a more favorable interaction with HDAC7, displaying a docking score of -9.633kcal/mol, as compared to the standard HDAC inhibitor suberoylanilide hydroxamic acid (SAHA), which exhibited a docking score of -8.244kcal/mol against HDAC7. The present study emphasizes the prospect of designing a potential 1,10-phenanthroline hydroxamic acid derivative as a novel dual HDAC and RR-inhibiting anti-cancer molecule.

Key structural requirements of benzamide derivatives for histone deacetylase inhibition: design, synthesis and biological evaluation.

Background: Histone deacetylase inhibitors (HDACIs) are important as anticancer agents. Objective: This study aimed to investigate some key structural features of HDACIs viathedesign, synthesisand biological evaluation of novel benzamide-based derivatives. Methods: Novel structures, designed using amolecular modification approach, were synthesized and biologically evaluated. Results: The results indicated that asubset of molecules with CH3/NH2 at R2 position possessselective antiproliferative activity. However, only those with an NH2 group showed HDACI activity. Importantly, the shorter the molecule length, the stronger HDACI. Among all, 7j was the most potent HDAC1-3 inhibitor and antiproliferative compound. Conclusion: The results of the present investigation couldprovide valuable structural knowledge applicable for the development of the HDACIs and benzamide-based antiproliferative agents in the future.

Exploration of the Tungsten(VI) complex of hydroxamic acid's RNA binding affinity, histone deacetylase inhibitory activity, and antioxidant activity

Ribonucleic acid (RNA) is a versatile molecule, thus the opportunity to target RNA is abundant. Hence, the current exploration deals with the interaction of a metal complex of hydroxamic acid with t-RNA, along with HDAC8 inhibition activity and antioxidant activity. Binding characteristics of complex 1, Bis(N-phenylbenzohydroxamato)Tungsten(VI), which is represented as [N-PBHA-W(VI)] with Torula yeast RNA (t-RNA) were investigated by using several types of spectroscopic techniques, measurements of viscosity, and computational study through molecular docking. The intrinsic binding constant, Kb was evaluated for complex 1 which shows changes in the shift of absorption spectra, and the intensity of spectra also varies. From fluorescence measurement, the binding constant of complex 1 towards t-RNA is 6.64 ± 0.05 × 105 M−1. Stern-Volmer quenching constant was calculated. Two displacement method sare performed by using the fluorescence spectroscopic technique which discloses a groove mode of binding. The groove mode of binding is also uncovered by viscosity measurement, which was observed by increasing the complex 1 concentration. An electrochemical investigation was carried out by using cyclic voltammetry. A circular dichroism study was also employed, which further suggests a strong binding occurred between the metal complex used and t-RNA. The docked postures of t-RNA with complex 1 expose the strong interactions which suggest a minor groove mode of binding. All the experimental evidence indicates that the interaction of complex 1 with t-RNA is a minor groove mode of binding which complements the molecular docking results. In-silico studies of HDAC8 inhibition activity of complex 1 reveal that the inhibition takes place mainly by hydrophobic interaction. DPPH–radical scavenging method employed for the antioxidant activity.

[Chidamide Promotes Osteogenic Differentiation of Bone Marrow Mesenchymal Stromal Cells from Patients with Myelodysplastic Syndromes].

To explore the effects and mechanisms of chidamide on the osteogenic differentiation of bone marrow mesenchymal stromal cells (MSC) from myelodysplastic syndromes (MDS). MSC were isolated and cultured from bone marrow of MDS patients and healthy donors. CCK-8 assay was used to detect the effects of chidamide on the proliferation of MSC. The effects of chidamide on the activity of histone deacetylase (HDAC) in MSC was measured by a fluorescence assay kit and Western blot. Alkaline phosphatase (ALP) activity was detected on day 3 and calcium nodule formation was observed by Alizarin Red staining on day 21 after osteogenic differentiation. The expression of early and late osteogenic genes was detected on day 7 and day 21, respectively. RT-PCR and Western blot were used to detect the effects of chidamide on mRNA and protein expression of RUNX2 which is the key transcription factor during osteogenesis. As the concentration of chidamide increased, the proliferation of MSC was inhibited. However, at a low concentration (1 μmol/L), chidamide had no significant inhibitory effect on MSC proliferation but significantly inhibited HDAC activity. In MSC from both MDS patients and healthy donors, chidamide (1 μmol/L) significantly increased ALP activity, calcium nodule formation, thereby mRNA expression of osteogenic genes, and restored the reduced osteogenic differentiation ability of MDS-MSC compared to normal MSC. Mechanistic studies showed that the osteogenic-promoting effect of chidamide may be related to the upregulation of RUNX2 . Chidamide can inhibit HDAC activity in MSC, upregulate the expression of the osteogenic transcription factor RUNX2, and promote the osteogenic differentiation of MDS-MSC.

Investigating Potential Cancer Therapeutics: Insight into Histone Deacetylases (HDACs) Inhibitions.

Histone deacetylases (HDACs) are enzymes that remove acetyl groups from ɛ-amino of histone, and their involvement in the development and progression of cancer disorders makes them an interesting therapeutic target. This study seeks to discover new inhibitors that selectively inhibit HDAC enzymes which are linked to deadly disorders like T-cell lymphoma, childhood neuroblastoma, and colon cancer. MOE was used to dock libraries of ZINC database molecules within the catalytic active pocket of target HDACs. The top three hits were submitted to MD simulations ranked on binding affinities and well-occupied interaction mechanisms determined from molecular docking studies. Inside the catalytic active site of HDACs, the two stable inhibitors LIG1 and LIG2 affect the protein flexibility, as evidenced by RMSD, RMSF, Rg, and PCA. MD simulations of HDACs complexes revealed an alteration from extended to bent motional changes within loop regions. The structural deviation following superimposition shows flexibility via a visual inspection of movable loops at different timeframes. According to PCA, the activity of HDACs inhibitors induces structural dynamics that might potentially be utilized to define the nature of protein inhibition. The findings suggest that this study offers solid proof to investigate LIG1 and LIG2 as potential HDAC inhibitors.

Trichostatin C Synergistically Interacts with DNMT Inhibitor to Induce Antineoplastic Effect via Inhibition of Axl in Bladder and Lung Cancer Cells.

Aberrant epigenetic modifications are fundamental contributors to the pathogenesis of various cancers. Consequently, targeting these aberrations with small molecules, such as histone deacetylase (HDAC) inhibitors and DNA methyltransferase (DNMT) inhibitors, presents a viable strategy for cancer therapy. The objective of this study is to assess the anti-cancer efficacy of trichostatin C (TSC), an analogue of trichostatin A sourced from the fermentation of Streptomyces sp. CPCC 203909. Our investigations reveal that TSC demonstrates potent activity against both human lung cancer and urothelial bladder cancer cell lines, with IC50 values in the low micromolar range. Moreover, TSC induces apoptosis mediated by caspase 3/7 and arrests the cell cycle at the G2/M phase. When combined with the DNMT inhibitor decitabine, TSC exhibits a synergistic anti-cancer effect. Additionally, protein analysis elucidates a significant reduction in the expression of the tyrosine kinase receptor Axl. Notably, elevated concentrations of TSC correlate with the up-regulation of the transcription factor forkhead box class O1 (FoxO1) and increased levels of the proapoptotic proteins Bim and p21. In conclusion, our findings suggest TSC as a promising anti-cancer agent with HDAC inhibitory activity. Furthermore, our results highlight the potential utility of TSC in combination with DNMT inhibitors for cancer treatment.

Abstract 7097: Integrated proteomics and metabolomics reveals new insight into the synergistic interaction of valproic acid plus simvastatin in prostate cancer xenograft model associated with down-modulation of YAP and TAZ signaling

Abstract Background: Despite advancements in therapeutic approaches, including taxane-based chemotherapy and androgen receptor targeting agents, metastatic castration-resistant prostate cancer (mCRPC) remains an incurable disease, underlying the need of novel strategies that can target the complexities of this disease and bypass the development of drug-resistance mechanisms. We previously demonstrated the synergistic antitumor interaction of the antiepileptic with histone deacetylase inhibitory activity valproic acid (VPA), and the lipid-lowering drug simvastatin (SIM). This combination sensitizes mCRPC cells to docetaxel treatment and revert docetaxel-resistance, both in vitro and in vivo models, by targeting cancer stem cells compartment via mevalonate pathway/YAP axis modulation. Methods: Proteomic and metabolomic/lipidomic analysis on tumor samples were performed by LC-MS/MS-based shotgun proteomics and by 1H-NMR approach, respectively. Progenesis QI for proteomics v. 4.2 was used as label-free quantification platform. Functional annotation analysis were performed by using the DAVID v6.8 (Database for Annotation, Visualization and Integrated Discovery); g:Profiler WikiPathways databases; Reactome version 66; Ingenuity Pathway Analysis software. Partial least squares-discriminant analysis (PLS-DA) and Loading plot were performed by Metabo Analyst v5.0 tool. Results: Tumor samples derived from 22Rv1 mCRPC cells xenografted mice, treated or not with VPA/SIM combination were characterized by a combined proteomic and metabolomic/lipidomic approach. In deep bioinformatics analysis confirmed a specific impact of VPA/SIM on Hippo pathway, with a clear down regulation of YAP and its targets (CTGF, CycD1 ANKH1) in treated vs untreated tumors, functionally related with modulation of cancer-related extracellular matrix remodelling and metabolic reprogramming. Treatment also downregulated TEAD transcription factor mediating YAP-induced expression, along with the upregulation of 14-3-3, responsible for YAP cytoplasmic retention and degradation, paralleled by the up-regulation of YAP up-stream negative regulators such as LATS1 and AMPK. VPA/SIM also modulated intermediates of TCA, urea cycles and glycolysis and decreased cholesterol and fatty acids. Conclusion: In summary, this study provides further insights into the molecular mechanism of the VPA/SIM antitumor effect suggesting the potential of repurposing these two generic and safe drugs in combination with standard antitumor therapies also in other tumors besides mCRCP. Citation Format: Federica Iannelli, Rita Lombardi, Susan Costantini, Maria Serena Roca, Laura Addi, Francesca Bruzzese, Elena Di Gennaro, Alfredo Budillon, Biagio Pucci. Integrated proteomics and metabolomics reveals new insight into the synergistic interaction of valproic acid plus simvastatin in prostate cancer xenograft model associated with down-modulation of YAP and TAZ signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7097.

Emerging therapeutic strategies in cancer therapy by HDAC inhibition as the chemotherapeutic potent and epigenetic regulator.

In developing new cancer medications, attention has been focused on novel epigenetic medicines called histone deacetylase (HDAC) inhibitors. Our understanding of cancer behavior is being advanced by research on epigenetics, which also supplies new targets for improving the effectiveness of cancer therapy. Most recently published patents emphasize HDAC selective drugs and multitarget HDAC inhibitors. Though significant progress has been made in emerging HDAC selective antagonists, it is urgently necessary to find new HDAC blockers with novel zinc-binding analogues to avoid the undesirable pharmacological characteristics of hydroxamic acid. HDAC antagonists have lately been explored as a novel approach to treating various diseases, including cancer. The complicated terrain of HDAC inhibitor development is summarized in this article, starting with a discussion of the many HDAC isotypes and their involvement in cancer biology, followed by a discussion of the mechanisms of action of HDAC inhibitors, their current level of development, effect of miRNA, and their combination with immunotherapeutic.

Formulating 10-hydroxycamptothecin into nanoemulsion with functional excipient tributyrin: An innovative strategy for targeted hepatic cancer chemotherapy

This study aimed to develop an innovative dosage form for 10-hydroxycamptothecin (HCPT), a chemotherapeutic agent with limited aqueous solubility and stability, to enhance its parenteral delivery and targeting to hepatic cancer. We formulated HCPT into a nanoemulsion using tributyrin, a dietary component with histone deacetylase inhibitor activity. The resulting HCPT-loaded tributyrin nanoemulsion (Tri-HCPT-E) underwent extensive evaluations. Tri-HCPT-E significantly improved the aqueous solubility, stability, and anti-cancer activities in HepG2 cells. Pharmacokinetic studies confirmed the increased stability and hepatic targeting, with Tri-HCPT-E leading to a 120-fold increase in plasma exposure of intact HCPT and a 10-fold increase in hepatic exposure compared to the commercial free solution. Co-administration of 17α-ethynylestradiol, an up-regulator of low-density lipoprotein (LDL) receptor, further enhanced the distribution and metabolism of HCPT, demonstrating an association between the LDL receptor pathway and hepatic targeting. Most importantly, Tri-HCPT-E exhibited superior in vivo anti-cancer efficacy in a mouse xenograft model compared to the commercial formulation, without causing escalated hepatic or renal toxicity. In conclusion, formulating HCPT into a nanoemulsion with tributyrin has proven to be an innovative and effective strategy for targeted hepatic cancer chemotherapy while tributyrin, a pharmacologically active dietary component, has emerged as a promising functional excipient for drug delivery.

Activity of alkoxyamide-based histone deacetylase inhibitors against Plasmodium falciparum malaria parasites

There are more than 240 million cases of malaria and 600,000 associated deaths each year, most due to infection with Plasmodium falciparum parasites. While malaria treatment options exist, new drugs with novel modes of action are needed to address malaria parasite drug resistance. Protein lysine deacetylases (termed HDACs) are important epigenetic regulatory enzymes and prospective therapeutic targets for malaria. Here we report the antiplasmodial activity of a panel of 17 hydroxamate zinc binding group HDAC inhibitors with alkoxyamide linkers and different cap groups. The two most potent compounds (4a and 4b) were found to inhibit asexual P. falciparum growth with 50% inhibition concentrations (IC50's) of 0.07 μM and 0.09 μM, respectively, and demonstrated >200-fold more selectivity for P. falciparum parasites versus human neonatal foreskin fibroblasts (NFF). In situ hyperacetylation studies demonstrated that 4a, 4b and analogs caused P. falciparum histone H4 hyperacetylation, suggesting HDAC inhibition, with structure activity relationships providing information relevant to the design of new Plasmodium-specific aliphatic chain hydroxamate HDAC inhibitors.

Design, synthesis and activity evaluation of arctigenin derivatives with HDAC inhibition activity.

Arctigenin, a natural product with diverse pharmacological activities, can inhibit cell proliferation and survival and has shown promising potential in cancer research. In this study, we designed a series of arctigenin derivatives with HDAC inhibitory activity based on the synergistic effects between HDAC inhibitors and arctigenin. Among them, compound B7 exhibited significantly higher antiproliferative activity in the MV411 cell line compared to the positive control, tucidinostat. Additionally, enzymatic activity testing was performed with compound B7. Further mechanistic studies indicated that compound B7 induced apoptosis through the Caspase-3 pathway in MV411 cells and enhanced histone acetylation levels in the MV411 cell line. These findings highlight the broad potential application of these arctigenin derivatives in cancer therapy.

Synergistic integration of histone deacetylase inhibitors apparently enhances the cytokine-induced killer cell efficiency in multiple myeloma via the NKG2D pathway.

The rapid recognition of epigenetic manipulation's potential in restricting cancer cell capabilities spurred translational initiatives, including histone deacetylase inhibitors (HDACis). Clinical trials on multiple myeloma (MM) demonstrated substantial benefits of HDACis, coupled with promising outcomes from cytokine-induced killer cell (CIK) immunotherapy. Intriguingly, the unexplored synergy of HDACis and CIK cell immunotherapy in MM prompted our study. We examined clinically relevant HDACis (panobinostat/LBH589 and romidepsin) alongside CIK cells derived from peripheral blood mononuclear cells across diverse MM cell lines (U266, RPMI8226, OPM-2 and NCI-H929). Utilising various in vitro methodologies, we investigated how HDACis enhance CIK cell lysis of myeloma cells through NKG2D/NKG2D ligand interactions. The results of our analysis indicated several key findings. (1) Enhanced cytotoxicity of CIK cells in MM cells when combined with HDACis. (2) Significant increase in apoptosis, suggesting HDACis and CIK may together enhance apoptotic effects in specific MM cell lines. (3) Elevated IFN-γ secretion and alterations in granzyme Bsecretion because of the independent activity of HDACis. (4) Notably, HDACis increased the expression of MICA/B and ULBP2, crucial for inducing antitumor cytotoxicity of NKTcells. Validation through NKG2D receptor blocking in CIK cells with a purified mouse antihuman NKG2D antibody further supported our findings. Our analyses provide sufficient evidence to consider this clinically forgotten instance (HDACis-CIK cell combination) as a therapeutic priority for MM treatment. Furthermore, we suggest that NKG2D/NKG2D-ligand interactions activating NK/NKTcells may contribute to enhanced myeloma cell lysis in response to HDACis treatment by CIK cells.

Design, synthesis, insilco study and biological evaluation of new isatin-sulfonamide derivatives by using mono amide linker as possible as histone deacetylase inhibitors.

Aim: To evaluate the cytotoxic activity of newly synthesized a series of novel HDAC inhibitors comprising sulfonamide as zinc binding group and Isatin derivatives as cap group joined by mono amide linker as required to act as HDAC inhibitors. Materials and Methods: The utilization of sulfonamide as zinc binding group joined by N-alkylation reaction with ethyl-bromo hexanoate as linker group that joined by amide reaction with Isatin derivatives as cap groups which known to possess antitumor activity in the designed of new histone deacetylase inhibitors and using the docking and MTT assay to evaluate the compounds. Results: Four compounds have been synthesized and characterized successfully by ART-FTIR, NMR and ESI-Ms. the compounds were synthesized and characterized by successfully by ART-FTIR, NMR and ESI- Ms. Assessed for their cytotoxic activity against human colon adenocarcinoma MCF-7 (IC50, I=105.15, II=60.00, III=54.11, IV=56.57, vorinostat=28.41) and hepatoblastoma HepG2 (IC50, I=63.91, II=135.18, III=118.85, IV=51.46, vorinostat=37.50). Most of them exhibited potent HDAC inhibitory activity and significant cytotoxicity. Conclusions: The synthesized compounds (I, II, III and IV) showed cytotoxicity toward MCF-7 and HepG2 cancer cell lines and their docking analysis provided a preliminary indication that they are viable [HDAC6] candidates.

Blockade of histone deacetylase activity affects transcription and splicing of neuronal and glial genes

The study of the molecular mechanisms underlying plastic processes in the nervous system is of great interest in modern neuroscience. It is important to understand that epigenetic modifications, which are crucial for the development and cellular differentiation, can also be involved in plastic processes in the adult nervous system. In our early work, we provided evidence that the expression of important memory-related genes, such as Prkcz and Prkci, can be regulated epigenetically [1]. In the current study, we extended the previous work to the systemic level by applying the RNA sequencing approach to evaluate global changes in the expression patterns of various genes during the induction of epigenetic rearrangements. Rat cortical neuron cultures were incubated with one of the nonselective histone deacetylase inhibitors (trichostatin A, TSA; sodium butyrate, NaB) to change the level of epigenetic regulation. Next, the total RNA was extracted and subjected to RNA-Seq libraries preparation and subsequent NGS-sequencing. Bioinformatics analysis of transcriptomic data revealed substantial overlapping of differentially expressed genes (DEGs) in NaB-treated and TSA-treated groups, indicating that different histone deacetylase (HDAC) inhibitors induce transcriptional changes in primary neuron cultures through common regulatory pathways irrespective of chemical structure of applied inhibitor. We found that histone deacetylase blockade is accompanied by a transition from proliferative processes to cellular differentiation. Gene Ontology (GO) analysis of DEGs datasets revealed that the upregulated genes were engaged in cell differentiation and specialization, tissue and embryonic morphogenesis, and the development of various peripheral tissues and organs. On the contrary, genes that reduce the expression under induction of epigenetic rearrangements were involved in biological processes associated with cell proliferation and, most interestingly, the specialization of various brain cells (neurons, astrocytes, oligodendrocytes). It was shown that the expression of a number of glial markers typical for astrocytes and oligodendrocytes was significantly reduced after application of HDAC inhibitors, which was also confirmed by quantitative PCR using specific primer pairs on selected target genes. During the data analysis, we also found a significant decrease in the expression of various neuronal markers associated with the cytoskeleton, the organization of pre- and postsynaptic endings, synaptic transmission. It is known that fine-tuning of various processes in the central nervous system is due to the production of different isoforms of proteins from the same gene due to the process of alternative splicing of the resulting mRNA. According to the literature, epigenetic rearrangements create a certain environment for the regulation of alternative splicing of different genes [2, 3]. It is shown that production of alternative isoforms can play an important role in various plastic processes [4, 5]. Therefore, using IsoformSwitchAnalyzeR and DEXSeq packages we analyzed the possibility of alternative splicing during the induction of epigenetic rearrangements in rat cortical neuron cultures by evaluating the abundance of various transcripts based on exon usage. We found that some glial genes and a large number of neuronal genes, especially those associated with postsynaptic organization and cell communication, were alternatively spliced after application of histone deacetylase inhibitors. Inhibition of HDAC activity in cortical neuron cultures mainly affected the choice of alternative transcription starts (ATSS) and terminators (ATTS), and to a lesser extent alternative splicing of exons. Obtained results were selectively confirmed by the quantitative PCR using specific pairs of primers for individual exons of different transcript isoforms. Thus, within this study, it was found that histone deacetylases play an important role in the specialization of various brain cells, and the suppression of their activity affects the expression and alternative splicing of various glial and neuronal marker genes. We do not exclude that global transcriptome changes caused by alternative splicing will lead to qualitative rearrangements of the neuron network, and this is the direction of future research.

Research on the Anti-tumor Activity of Novel Histone Deacetylase Inhibitors based on 3D QSAR Model

Background: Histone deacetylases (HDACs) pertain to the category of Zn2 + or nicotinamide adenine dinucleotide (NAD+)- dependent proteolytic enzymes. While the antitumor effect of HDAC inhibitors alone has been demonstrated and the effect of HDAC inhibitors on solid tumors is not ideal, which considerably limits their clinical use. Therefore, the search for novel HDAC inhibitors equipped with specific inhibitors is extremely urgent and necessary. Methods: 3D-QSAR was employed to investigate insights into the crucial structural element that effect the activity of novel HDAC small molecule inhibitors. The best saliency CoMFA and CoMSIA models are obtained using 55 molecules in the training set and 16 molecules in the test set. Results: The statistical quality of the generated model is demonstrated by internal and external cross-validations. The CoMFA model obtained satisfactory values (q2 = 0.664, r2 = 0.917, SEE = 0.217) while optimized CoMSIA model exceed with (q2 = 0.672, r2 = 0.948, SEE = 0.175). Conclusion: The statistical parameters from 3D-QSAR models reveal that the results are reliable and significant with strong predictive ability. These theoretical results may contribute to the design of novel HDAC small molecule inhibitors with enhanced activity for the treatment of cancer.

Exploration of quinazoline-tethered hydroxamic acid derivatives as HDAC inhibitors for anticancer activity: Design, synthesis, molecular docking, and biological evaluation

In the past two decades, targeted cancer therapy has emerged as a novel class of anticancer therapeutics, besides traditional chemotherapy, surgery, and radiotherapy. Inhibition of HDACs represents a promising avenue for cancer therapeutics and initial success in treating select T-cell lymphomas has led to the FDA approval of four HDAC-targeted agents. The majority of currently available HDAC inhibitors have weak anticancer activity, with significant side effects. To address these drawbacks, in the present work we have designed and synthesized a novel series of histone deacetylase inhibitors combining 2-(4-substituted phenyl) quinazoline bioactive fragment as cap group and N-hydroxycinnamamide/ N-hydroxybenzamide as linker group, and evaluated for their cytotoxic activity against the three cancer cell lines (HeLa, MCF-7 and HCT-116) and HDAC inhibitory activity. All three cancer cell lines were most sensitive to the N-hydroxyacrylamide derivatives (5a-f) as compared to N-hydroxybenzamides (7a-f) derivatives. In particular, compound 5a (0.39, 0.26, 0.41 µM respectively) and 5b (0.27, 0.57, 0.32 µM respectively) were found to be the most potent derivatives among all tested cell lines. For HDAC inhibitory activity, it was found that compounds 5a, 5b, and 5d possessed comparable, even better HDAC inhibitory activity as compared to SAHA. These compounds also tested in vitro heamolytic activity, most of the compounds found biocompatible with human erythrocytes thereby evidencing the lack of haemolytic toxicity of anticancer drugs. In silico ADMET and molecular docking studies further corroborated with the experimental results. Overall, the new synthesized compounds exhibited significant HDAC and cytotoxic activity. Also, the different substituents and unsaturated bond influenced both HDAC inhibitory and cytotoxic activity. The outcome of the current work is that several potential HDAC inhibitors have emerged for further design of more potent HDAC inhibitors with better cytotoxicity.

Abstract LB_C11: Small-molecule bifunctional inhibitors of PARP1/2 and HDAC enzymes

Abstract Background: Poly(ADP-ribose) polymerase (PARP) plays a major role in DNA repair and PARP inhibitors (PARPi) have shown promise for the treatment of cancers with DNA damage repair defects, such as BRCA mutations. PARPi are currently approved for treatment of BRCA-mutated cancers and as a maintenance therapy for patients who have responded to platinum-based chemotherapy. To improve efficacy, overcome resistance, and expand the usage of PARPi to non-BRCA mutated disease, combination therapies with PARPi have emerged as an area of interest. Histone deacetylases (HDACs) play a major role in DNA repair and inhibition of HDACs has been shown to reduce tumor growth. PARPi combined with HDACi has shown enhanced efficacy in pre-clinical studies in various cancers, and a clinical trial of olaparib and vorinostat against metastatic breast cancer is ongoing. However, combination therapies can be limited clinically due to overlapping toxicities and differing pharmacokinetics. Here, we report the efficacy of a novel class of bifunctional small-molecule compounds (kt-3000) with both PARP1 and PARP2 inhibitory and HDAC inhibitory activities. Methods: PARP1 and PARP2 activity was measured using Trevigen Universal Colorimetric PARP Assay kit and BPS Bioscience PARP2 Colorimetric Assay kit respectively. HDAC activity was measured using HeLa nuclear extracts and a fluorogenic peptide-based biochemical assay. In vitro metabolism was determined by HPLC after incubation with human liver microsomes for up to 45 mins. Pharmacokinetic profiling was examined in mice up to 6 h after oral/intraperitoneal (IP) dosing. Results: kt-3000 compounds showed potent inhibition of PARP1 and PARP2 activity with IC50 values comparable to olaparib (low nM) and inhibition of HDACs with IC50 values in the low µM range. Metabolic and pharmacokinetic profiling suggest drug-like qualities in the class. Conclusion: kt-3000 molecules demonstrate potent inhibition of PARP1/2 and HDAC activities, with suitable pharmacokinetic properties for oral delivery. Further refinement and development of these bifunctional single-molecule inhibitors may offer a novel therapeutic opportunity for treatment of cancers with and without DNA damage repair defects. Citation Format: Sarah Truong, Louise Ramos, Beibei Zhai, Jay Joshi, Fariba Ghaidi, Mona Marzban, Hans Adomat, Charles Chen, John Langlands, Dennis Brown, Jeffrey Bacha, Colin Collins, Poul Sorensen, Wang Shen, Mads Daugaard. Small-molecule bifunctional inhibitors of PARP1/2 and HDAC enzymes [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_C11.

Abstract LB_C03: Protein translation inhibition enforces histone deacetylase inhibitor activity resulting in synergistic pancreatic cancer cell death

Abstract Management of pancreatic cancer presents significant challenges due to late-stage diagnosis, aggressive tumor biology, and limited efficacy of existing treatment options. Gemcitabine and FOLFIRINOX (folinic acid, 5-FU, irinotecan hydrochloride, oxaliplatin) are standard treatments for advanced pancreatic cancer. Despite these therapies the overall 5-year survival rate for pancreatic cancer patients is at 12%, largely due to drug resistance. Thus, there is a critical need to explore new therapeutic strategies.  Our study explores a small molecule combination that induces epigenetic reprogramming as a potential novel therapeutic strategy for pancreatic cancer. We have identified marked sensitivity of pancreatic cancer cells to the combination of a novel inhibitor of RNA helicase eIF4A, DMPatA (MZ735), and a histone deacetylase (HDAC) inhibitor, romidepsin. A short-term, low dose romidepsin treatment, when combined with MZ735, triggers persistent global histone acetylation, transcriptional upregulation, replication inhibition, and augmented DNA damage. This combined effect induces a synergistic anti-proliferative response in pancreatic cancer cells. We have identified a tolerable protocol for this combination regimen in animals, demonstrating its efficacy against tumor growth in a MIA PaCa-2 xenograft mouse model of pancreatic cancer. Treatment with the combination resulted in inhibition and then complete suppression of tumor growth in animals for 39 days. Our in vitro studies aimed at understanding the mechanism of this combination treatment showed that at low doses of romidepsin monotherapy, histone acetylation rapidly faded, while robust acetylation persisted to 18 and 24 hours with the combination.  Additionally, R-loop accumulation was observed using confocal microscopy and DRIP-qPCR, along with a reduction in replication fork speed, which might account for the identified DNA damage and genome instability. The combination treatment significantly reduces acetyl-CoA and c-MYC protein levels and disrupts glycolysis and oxidative phosphorylation. We show that a structurally different HDAC inhibitor exhibits the same synergistic effects when co-administered with MZ735, confirming a unique method of eliciting synthetic lethality in PDAC cells. In conclusion, this combination shows significant antitumor activity in both in vitro and in vivo models of pancreatic cancer and warrant translation to the clinic. Citation Format: Maryam Safari, Luigi Scotto, Agnes Basseville, Thomas Litman, Haoran Xue, Luba Petrukhin, Ping Zhou, Christopher Damoci, Minhzhao Zhu, Kenneth Hull, Kenneth P Olive, Antonio T Fojo, Daniel Romo, Susan E Bates. Protein translation inhibition enforces histone deacetylase inhibitor activity resulting in synergistic pancreatic cancer cell death [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr LB_C03.

Design, synthesis, and histone deacetylase inhibition study of novel 4-(2-aminoethyl) phenol derivatives.

Histone deacetylases (HDACs) have been identified as promising targets for anticancer treatment. The study demonstrates virtual screening, molecular docking, and synthesis of 4-(2-aminoethyl) phenol derivatives as HDAC inhibitors. The virtual screening and molecular docking analysis led to the identification of 10 representative compounds, which were evaluated based on their drug-like properties. The results demonstrated that these compounds effectively interacted with the active site pocket of HDAC 3 through π-stacking, Zn2+ coordination, hydrogen bonding, and hydrophobic interactions with catalytic residues. Furthermore, a series of 4-(2-aminoethyl) phenol derivatives were synthesized, and their HDAC inhibitory activity was evaluated. Compounds 18 and 20 showed significant HDAC inhibitory activity of 64.94 ± 1.17% and 52.45 ± 1.45%, respectively, compared to the solvent control. The promising results of this study encourage further research on 4-(2-aminoethyl) phenol derivatives and may provide significant insight into the design of novel small molecule HDAC inhibitors to fight against target-specific malignancies of chronic obstructive pulmonary disease and nonsmall cell lung cancer in the future.