Histone deacetylases and cancer: causes and therapies

Iridium(III) complexes as novel theranostic small molecules for medical diagnostics, precise imaging at a single cell level and targeted anticancer therapy

Medical applications of iridium (III) complexes include their use as state-of-the-art theranostic agents - molecules that combine therapeutic and diagnostic functions into a single entity. These complexes offer a promising avenue in medical diagnostics, precision imaging at single-cell resolution and targeted anticancer therapy due to their unique properties. In this review we report a short summary of their application in medical diagnostics, imaging at single-cell level and targeted anticancer therapy. The exceptional photophysical properties of Iridium (III) complexes, including their brightness and photostability, make them excellent candidates for bioimaging. They can be used to image cellular processes and the microenvironment within single cells with unprecedented clarity, aiding in the understanding of disease mechanisms at the molecular level. Moreover the iridium (III) complexes can be designed to selectively target cancer cells,. Upon targeting, these complexes can act as photosensitizers for photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon light activation to induce cell death. The integration of diagnostic and therapeutic capabilities in Iridium (III) complexes offers the potential for a holistic approach to cancer treatment, enabling not only the precise eradication of cancer cells but also the real-time monitoring of treatment efficacy and disease progression. This aligns with the goals of personalized medicine, offering hope for more effective and less invasive cancer treatment strategies.

Pancreatic ductal adenocarcinoma cells reshape the immune microenvironment: Molecular mechanisms and therapeutic targets

Pancreatic ductal adenocarcinoma (PDAC) is a digestive system malignancy characterized by challenging early detection, limited treatment alternatives, and generally poor prognosis. Although there have been significant advancements in immunotherapy for hematological malignancies and various solid tumors in recent decades, with impressive outcomes in recent preclinical and clinical trials, the effectiveness of these therapies in treating PDAC continues to be modest. The unique immunological microenvironment of PDAC, especially the abnormal distribution, complex composition, and variable activation states of tumor-infiltrating immune cells, greatly restricts the effectiveness of immunotherapy. Undoubtedly, integrating data from both preclinical models and human studies helps accelerate the identification of reliable molecules and pathways responsive to targeted biological therapies and immunotherapies, thereby continuously optimizing therapeutic combinations. In this review, we delve deeply into how PDAC cells regulate the immune microenvironment through complex signaling networks, affecting the quantity and functional status of immune cells to promote immune escape and tumor progression. Furthermore, we explore the multi-modal immunotherapeutic strategies currently under development, emphasizing the transformation of the immunosuppressive environment into an anti-tumor milieu by targeting specific molecular and cellular pathways, providing insights for the development of novel treatment strategies.

A Live-Cell Epigenome Manipulation by Photo-Stimuli-Responsive Histone Methyltransferase Inhibitor

Post-translational modifications on the histone H3 tail regulate chromatin structure, impact epigenetics, and hence the gene expressions. Current chemical modulation tools, such as unnatural amino acid incorporation, protein splicing, and sortase-based editing, have allowed for the modification of histones with various PTMs in cellular contexts, but are not applicable for editing native chromatin. The use of small organic molecules to manipulate histone-modifying enzymes alters endogenous histone PTMs but lacks precise temporal and spatial control. To date, there has been no achievement in modulating histone methylation in living cells with spatiotemporal resolution. In this study, a new method is presented for temporally manipulating histone dimethylation H3K9me2 using a photo-responsive inhibitor that specifically targets the methyltransferase G9a on demand. The photo-caged molecule is stable under physiological conditions and cellular environments, but rapidly activated upon exposure to light, releasing the bioactive component that can immediately inhibit the catalytic ability of the G9a in vitro. Besides, this masked compound could also efficiently reactivate the inhibition of methyltransferase activity in living cells, subsequently suppress H3K9me2, a mark that regulates various chromatin functions. Therefore, the chemical system will be a valuable tool for manipulating the epigenome for therapeutic purposes and furthering the understanding of epigenetic mechanisms.

Psammaplin A analogues with modified disulfide bond targeting histone deacetylases: Synthesis and biological evaluation

Psammaplin A (PsA), a symmetrical bromotyrosine-derived disulfide marine metabolite, has been reported could inhibit HDAC1/2/3 through its thiol monomer. Inspired by the disuflide bond structure of this marine natural product, we designed and synthesized a series of PsA analogues, in which the disulfide bond of PsA was replaced with diselenide bond or cyclic disulfide/diselenide/selenenylsulfide motifs. We also studied the HDAC inhibition, cell growth inhibition, and apoptosis induction of these PsA analogues. The results showed that, all the synthetic diselenide analogues and cyclic selenenyl sulfide compounds exhibited better antiproferative activity than their counterpart of disulfide analogues. Among the prepared analogues, diselenide analogue P-503 and P-116 significantly increased the ability of inhibiting HDAC6 and induced apoptosis and G2/M cell cycle arrest. However, cyclic selenenylsulfides analogues P-111 lost its HDAC inhibitory ability and exhibited no effect on cell cycle and apoptosis, indicating that the anti-proliferative mechanism of cyclic selenenylsulfides analogues has changed.

The Bioequivalence of Abexinostat (CRA-024781) Tosylate Tablets (20 mg) in Chinese Healthy Subjects Under Fasting Conditions

This study aimed to investigate the pharmacokinetic parameters of single oral administration of postchange and prechange abexinostat (CRA-024781) tosylate tablets in Chinese healthy subjects under fasting conditions, and assess the bioequivalence (BE) of the 2 formulations (Test [T1] and Reference [T2]). This study was a randomized, open-label, 2-formulation, fasting administration, single-dose, 2-sequence, 2-cycle, crossover BE study. Thirty-six subjects were enrolled in the study and 33 subjects completed 2 cycles. The plasma concentrations were determined by liquid chromatography-tandem mass spectrometry. The 90% confidence intervals (CIs) for the Cmax, AUC0-t, and AUC0-∞ of CRA-024781 and its 2 major metabolites (PCI-27789 and PCI-27887, both metabolites are pharmacologically inactive on HDAC1) fell within the acceptable range of 80%-125%. The results suggest that the CRA-024781 test preparation (Test [T1]) is bioequivalent to the reference preparation (Reference [T2]) in healthy Chinese subjects under fasting conditions.

Dysfunction of the carnitine cycle in tumor progression

The carnitine cycle is responsible for the transport of cytoplasmic fatty acids to the mitochondria for subsequent β-oxidation to maintain intracellular energy homeostasis. Recent studies have identified abnormalities in the carnitine cycle in various types of tumors; these abnormalities include the altered expression levels of carnitine cycle-related metabolic enzymes and transport proteins. Dysfunction of the carnitine cycle has been shown to influence tumorigenesis and progression by altering intracellular oxidative and inflammatory status or regulating tumor metabolic flexibility. Many therapeutic strategies targeting the carnitine cycle are actively being explored to modify the dysfunction of the carnitine cycle in patients with malignant tumors; such approaches include carnitine cycle-related enzyme inhibitors and exogenous carnitine supplementation. Therefore, here, we review the studies of carnitine in tumors, aiming to scientifically illustrate the dysfunction of the carnitine cycle in tumor progression and provide new ideas for further research.

Upregulation of the tumor suppressor gene LIN9 enhances tumorigenesis and predicts poor prognosis of lung adenocarcinoma

Background

LIN9, a gene associated with various cancers, is considered a tumor suppressor. However, the role of LIN9 in lung adenocarcinoma (LUAD) remains unknown. In this study, we aimed to assess the role of LIN9 in the occurrence and prognosis of LUAD.

Methods

Using three-tier HTSeq count RNA sequencing data from The Cancer Genome Atlas, we assessed LIN9 expression for the LUAD dataset using the DESeq2 R package and RT-qPCR experiments. Biological functions were assessed using gene set enrichment analysis (clusterProfiler and GOplot). The expression of LIN9 and the infiltration of immune cells were assessed by Single-sample gene set enrichment analysis. We conducted correlation study using clinical characteristics and receiver operating characteristic curve analysis. The predictive value of LIN9 was determined using univariate and multivariate Cox regression as well as Kaplan-Meier analysis. Additionally, functional studies were conducted to validate its role in the progression of LUAD.

Results

Expression of LIN9 was significantly elevated in LUAD, primarily influencing cell cycle, division, and signaling pathways. High LIN9 expression correlated positively with the infiltration of Th2 cells and inversely with that of plasmacytoid dendritic cells. Furthermore, LIN9 was associated with older age and advanced clinical stages, posing risks to overall, progression-free, and disease-specific survival. LIN9 served as a good diagnostic marker, particularly in females, patients aged over 65, and those with clinical N1-3 and M1 stages. Elevated LIN9 expression enhanced proliferation, migration, and invasion of LUAD cells.

Conclusion

High LIN9 expression potentially contributes to LUAD occurrence through cell cycle regulation and chromosomal modification. It promotes the malignant characteristics of LUAD cells and holds prognostic value for affected patients.

Ferrocenyl Azoles: Versatile N-Containing Heterocycles and their Anticancer Activities

The medicinal chemistry of ferrocene has gained its momentum after the discovery of biological activities of ferrocifen and ferroquine. These ferrocenyl drugs have been designed by replacing the aromatic moiety of the organic drugs, tamoxifen and chloroquine respectively, with a ferrocenyl unit. The promising biological activities of these ferrocenyl drugs have paved a path to explore the medicinal applications of several ferrocenyl conjugates. In these conjugates, the ferrocenyl moiety has played a vital role in enhancing or imparting the anticancer activity to the molecule. The ferrocenyl conjugates induce the cytotoxicity by generating reactive oxygen species and thereby damaging the DNA. In medicinal chemistry, the five membered nitrogen heterocycles (azoles) play a significant role due to their rigid ring structure and hydrogen bonding ability with the biomolecules. Several potent drug candidates with azole groups have been in use as chemotherapeutics. Considering the importance of ferrocenyl moiety and azole groups, several ferrocenyl azole conjugates have been synthesized and screened for their biological activities. Hence, in the view of a wide scope in the development of potent drugs based on ferrocenyl azole conjugates, herein we present the details of synthesis and the anticancer activities of ferrocenyl compounds bearing azole groups such as imidazole, triazoles, thiazole and isoxazoles.

Expression of glucocorticoid receptor and HDACs in airway smooth muscle cells is associated with response to steroids in COPD

BACKGROUND

Steroid insensitivity in Chronic Obstructive Pulmonary Disease (COPD) presents a problem for controlling the chronic inflammation of the airways. The glucocorticoid receptor (GR) mediates the intracellular signaling of inhaled corticosteroids (ICS) by interacting with transcription factors and histone deacetylases (HDACs). The aim of this study was to assess if COPD patients' response to ICS in vivo, may be associated with the expression of GR, the complex of GR with transcription factors, and the expression of various HDACs in vitro.

METHODS

Primary airway smooth muscle cells (ASMC) were established from endobronchial biopsies obtained from patients with asthma (n = 10), patients with COPD (n = 10) and subjects that underwent diagnostic bronchoscopy without pathological findings and served as controls (n = 6). ASMC were also established from 18 COPD patients, 10 responders and 8 non-responders to ICS, who participated in the HISTORIC study, an investigator-initiated and driven clinical trial that proved the hypothesis that COPD patients with high ASMC in their endobronchial biopsies respond better to ICS than patients with low ASMC. Expression of GR and its isoforms GRα and GRβ and HDACs was investigated in primary ASMC in the absence or in the presence of dexamethasone (10- 8M) by western blotting. The complex formation of GR with transcription factors was assessed by co-immunoprecipitation.

RESULTS

Expression of GR and its isoform GRα but not GRβ was significantly reduced in ASMC from COPD patients as compared to controls. There were no significant differences in the expression of GR, GRα and GRβ between responders and non-responders to ICS. However, treatment with dexamethasone upregulated the expression of total GR (p = 0.004) and GRα (p = 0.005) after 30 min in responders but not in non-responders. Τhe formation of the complex GR-c-Jun was increased 60 min after treatment with dexamethasone only in responders who exhibited significantly lower expression of HDAC3 (p = 0.005) and HDAC5 (p < 0.0001) as compared to non-responders.

CONCLUSIONS

These data suggest that ASMC from COPD patients who do not respond to treatment with ICS, are characterized by reduced GR-c-Jun complex formation and increased expression of HDAC3 and HDAC5.

TRIAL REGISTRATION

ISRCTN11017699 (Registration date: 15/11/2016).

Exploring different classification-dependent QSAR modelling strategies for HDAC3 inhibitors in search of meaningful structural contributors

Histone deacetylase 3 (HDAC3), a Zn2+-dependent class I HDACs, contributes to numerous disorders such as neurodegenerative disorders, diabetes, cardiovascular disease, kidney disease and several types of cancers. Therefore, the development of novel and selective HDAC3 inhibitors might be promising to combat such diseases. Here, different classification-based molecular modelling studies such as Bayesian classification, recursive partitioning (RP), SARpy and linear discriminant analysis (LDA) were conducted on a set of HDAC3 inhibitors to pinpoint essential structural requirements contributing to HDAC3 inhibition followed by molecular docking study and molecular dynamics (MD) simulation analyses. The current study revealed the importance of hydroxamate function for Zn2+ chelation as well as hydrogen bonding interaction with Tyr298 residue. The importance of hydroxamate function for higher HDAC3 inhibition was noticed in the case of Bayesian classification, recursive partitioning and SARpy models. Also, the importance of substituted thiazole ring was revealed, whereas the presence of linear alkyl groups with carboxylic acid function, any type of ester function, benzodiazepine moiety and methoxy group in the molecular structure can be detrimental to HDAC3 inhibition. Therefore, this study can aid in the design and discovery of effective novel HDAC3 inhibitors in the future.

Protein neddylation and its role in health and diseases

NEDD8 (Neural precursor cell expressed developmentally downregulated protein 8) is an ubiquitin-like protein that is covalently attached to a lysine residue of a protein substrate through a process known as neddylation, catalyzed by the enzyme cascade, namely NEDD8 activating enzyme (E1), NEDD8 conjugating enzyme (E2), and NEDD8 ligase (E3). The substrates of neddylation are categorized into cullins and non-cullin proteins. Neddylation of cullins activates CRLs (cullin RING ligases), the largest family of E3 ligases, whereas neddylation of non-cullin substrates alters their stability and activity, as well as subcellular localization. Significantly, the neddylation pathway and/or many neddylation substrates are abnormally activated or over-expressed in various human diseases, such as metabolic disorders, liver dysfunction, neurodegenerative disorders, and cancers, among others. Thus, targeting neddylation becomes an attractive strategy for the treatment of these diseases. In this review, we first provide a general introduction on the neddylation cascade, its biochemical process and regulation, and the crystal structures of neddylation enzymes in complex with cullin substrates; then discuss how neddylation governs various key biological processes via the modification of cullins and non-cullin substrates. We further review the literature data on dysregulated neddylation in several human diseases, particularly cancer, followed by an outline of current efforts in the discovery of small molecule inhibitors of neddylation as a promising therapeutic approach. Finally, few perspectives were proposed for extensive future investigations.

Carboplatin plus Paclitaxel in Combination with the Histone Deacetylate Inhibitor, Vorinostat, in Patients with Recurrent Platinum-Sensitive Ovarian Cancer

Background: This phase II study evaluated the efficacy and safety of the histone deacetylase (HDAC) inhibitor, vorinostat, administered in combination with paclitaxel and carboplatin in patients with platinum sensitive recurrent ovarian cancer. Methods: Women with recurrent platinum-sensitive ovarian, peritoneal, or Fallopian tube carcinoma, a performance status of 0-2, and good overall organ function were eligible. Patients received 6 courses of paclitaxel (175 mg/m2) and carboplatin area under the curve (AUC) of 5.0 mg/mL/min administered via intravenous infusion on day 1 of a 3-week schedule. In addition, patients received vorinostat 400 mg orally once daily on days -4 through 10 of Cycle 1 and days 1 through 14 of each subsequent treatment cycle. The primary endpoints were progression-free survival (PFS) and adverse events. The secondary endpoints were the objective response rate and overall survival. Results: Fifty-five patients were included. CR was obtained in 14 patients (26.4%) and PR in 19 patients (35.8%), resulting in an ORR of 62.2%. Twenty patients (37.7%) had SD. The median duration of response (DoR) was 12.6 (range 6-128) months. The median PFS was 11.6 months (95% CI, 10.3-18.0; p < 0.001). Median OS was 40.6 months (95% Cl, 25.1-56.1). The most common treatment-related adverse events (all grades) were fatigue, anemia, thrombocytopenia, neutropenia, anorexia, nausea, pain, sensory neuropathy, myalgia, stomatitis and diarrhea. Conclusions: Vorinostat combined with carboplatin plus paclitaxel was tolerable and generated significant responses including a long median overall survival in recurrent platinum-sensitive ovarian cancer.

Epigenetic priming targets tumor heterogeneity to shift transcriptomic phenotype of pancreatic ductal adenocarcinoma towards a Vitamin D susceptible state

As a highly heterogeneous tumor, pancreatic ductal adenocarcinoma (PDAC) exhibits non-uniform responses to therapies across subtypes. Overcoming therapeutic resistance stemming from this heterogeneity remains a significant challenge. Here, we report that Vitamin D-resistant PDAC cells hijacked Vitamin D signaling to promote tumor progression, whereas epigenetic priming with glyceryl triacetate (GTA) and 5-Aza-2'-deoxycytidine (5-Aza) overcame Vitamin D resistance and shifted the transcriptomic phenotype of PDAC toward a Vitamin D-susceptible state. Increasing overall H3K27 acetylation with GTA and reducing overall DNA methylation with 5-Aza not only elevated the Vitamin D receptor (VDR) expression but also reprogrammed the Vitamin D-responsive genes. Consequently, Vitamin D inhibited cell viability and migration in the epigenetically primed PDAC cells by activating genes involved in apoptosis as well as genes involved in negative regulation of cell proliferation and migration, while the opposite effect of Vitamin D was observed in unprimed cells. Studies in genetically engineered mouse PDAC cells further validated the effects of epigenetic priming for enhancing the anti-tumor activity of Vitamin D. Using gain- and loss-of-function experiments, we further demonstrated that VDR expression was necessary but not sufficient for activating the favorable transcriptomic phenotype in respond to Vitamin D treatment in PDAC, highlighting that both the VDR and Vitamin D-responsive genes were prerequisites for Vitamin D response. These data reveal a previously undefined mechanism in which epigenetic state orchestrates the expression of both VDR and Vitamin D-responsive genes and determines the therapeutic response to Vitamin D in PDAC.

Recent Developments and Future Perspectives of Purine Derivatives as a Promising Scaffold in Drug Discovery

Numerous purine-containing compounds have undergone extensive investigation for their medical efficacy across various diseases. The swift progress in purine-based medicinal chemistry has brought to light the therapeutic capabilities of purine-derived compounds in addressing challenging medical conditions. Defined by a heterocyclic ring comprising a pyrimidine ring linked with an imidazole ring, purine exhibits a diverse array of therapeutic attributes. This review systematically addresses the multifaceted potential of purine derivatives in combating various diseases, including their roles as anticancer agents, antiviral compounds (anti-herpes, anti-HIV, and anti-influenzae), autoimmune and anti-inflammatory agents, antihyperuricemic and anti-gout solutions, antimicrobial agents, antitubercular compounds, anti-leishmanial agents, and anticonvulsants. Emphasis is placed on the remarkable progress made in developing purine-based compounds, elucidating their significant target sites. The article provides a comprehensive exploration of developments in both natural and synthetic purines, offering insights into their role in managing a diverse range of illnesses. Additionally, the discussion delves into the structure-activity relationships and biological activities of the most promising purine molecules. The intriguing capabilities revealed by these purine-based scaffolds unequivocally position them at the forefront of drug candidate development. As such, this review holds potential significance for researchers actively involved in synthesizing purine-based drug candidates, providing a roadmap for the continued advancement of this promising field.

Synthesis of N-aminophalimides derived from α-amino acids: Theoretical study to find them as HDAC8 inhibitors by docking simulations and in vitro assays

Phthalimides are valuable for synthesis and biological properties. New acetamides 3(a-c) and 4(a-c) were synthesized and characterized as precursors for novel N-aminophalimides 5(a-c) and 6(a-c). Structures of 4a, 5(a-b), and 6(a-b) were confirmed by single crystal X-ray. Docking studies identified compounds with favorable Gibbs free energy values for binding to histone deacetylase 8 (HDAC8), an enzyme targeted for anticancer drug development. These compounds bound to both the orthosteric and allosteric pockets of HDAC8, similar to Trichostatin A (TSA), an HDAC8 inhibitor. 6(a-c) contain hydroxyacetamide moiety as a zinc-binding group, a phthalimide moiety as a capping group, and aminoacetamide moiety as a linker group, which are important for ligand-receptor binding. ΔG values indicated that compounds 5b, 6b, and 6c had higher affinity for HDAC8 in the allosteric pocket compared to TSA. In vitro evaluation of inhibitory activities on HDAC8 revealed that compounds 3(a-c) and 5(a-c) showed similar inhibitory effects (IC50 ) ranging from 0.445 to 0.751 μM. Compounds 6(a-c) showed better affinity, with 6a (IC50  = 28 nM) and 6b (IC50  = 0.18 μM) showing potent inhibitory effects slightly lower than TSA (IC50  = 26 nM). These findings suggest that the studied compounds hold promise as potential candidates for further biological investigations.

HDAC inhibitors: Promising agents for leukemia treatment

The essential role of epigenetic modification in the pathogenesis of a series of cancers have gradually been recognized. Histone deacetylase (HDACs), as well-known epigenetic modulators, are responsible for DNA repair, cell proliferation, differentiation, apoptosis and angiogenesis. Studies have shown that aberrant expression of HDACs is found in many cancer types. Thus, inhibition of HDACs has provided a promising therapeutic approach alternative for these patients. Since HDAC inhibitor (HDACi) vorinostat was first approved by the Food and Drug Administration (FDA) for treating cutaneous T-cell lymphoma (CTCL) in 2006, the combination of HDAC inhibitors with other molecules such as chemotherapeutic drugs has drawn much attention in current cancer treatment, especially in hematological malignancies therapy. Up to now, there have been more than twenty HDAC inhibitors investigated in clinic trials with five approvals being achieved. Indeed, Histone deacetylase inhibitors promote or enhance several different anticancer mechanisms and therefore are in evidence as potential antileukemia agents. In this review, we will focus on possible mechanisms by how HDAC inhibitors exert therapeutic benefit and their clinical utility in leukemia.

Lansoprazole as a potent HDAC2 inhibitor for treatment of colorectal cancer: An in-silico analysis and experimental validation

BACKGROUND

Histone deacetylase 2 (HDAC2), belonging to the class I HDAC family, holds significant therapeutic potential as a crucial target for diverse cancer types. As key players in the realm of epigenetic regulatory enzymes, histone deacetylases (HDACs) are intricately involved in the onset and progression of cancer. Consequently, pursuing isoform-specific inhibitors targeting histone deacetylases (HDACs) has garnered substantial interest in both biological and medical circles. The objective of the present investigation was to employ a drug repurposing approach to discover novel and potent HDAC2 inhibitors.

MATERIALS AND METHODS

In this study, our protocol is presented on virtual screening to identify novel potential HDAC2 inhibitors through 3D-QSAR, molecular docking, pharmacophore modeling, and molecular dynamics (MD) simulation. Afterward, In-vitro assays were employed to evaluate the cytotoxicity, apoptosis, and migration of HCT-116 cell lines under treatment of hit compound and valproic acid as a control inhibitor. The expression levels of HDAC2, TP53, BCL2, and BAX were evaluated by QRT-PCR.

RESULTS

RMSD, RMSF, H-bond, and DSSP analysis results confirmed that among bioinformatically selected compounds, lansoprazole exhibited the highest HDAC2 inhibitory potential. Experimental validation revealed that lansoprazole displayed significant antiproliferative activity. The determined IC50 value was 400 ± 2.36 μM. Furthermore, the apoptotic cells ratio concentration-dependently increased under Lansoprazole treatment. Results of the Scratch assay indicated that lansoprazole led to decreasing the migration of CRC cells. Finally, under Lansoprazole treatment the expression level of BCL2 and HDAC2 decreased and BAX and TP53 increased.

CONCLUSION

Taking together the results of the current study indicated that Lansoprazole as a novel HDAC2 inhibitor, could be used as a potential therapeutic agent for the treatment of CRC. Although, further experimental studies should be performed before using this compound in the clinic.

Histone deacetylase inhibitor sodium butyrate regulates the activation of toll-like receptor 4/interferon regulatory factor-3 signaling pathways in prostate cancer cells

CONTEXT

The covalent acetylation and deacetylation of histone proteins by the histone deacetylase (HDAC) enzymes can be considered a novel therapeutic target in prostate cancer (PCa) cells. Sodium butyrate (NaBu) is a HDAC inhibitor (HDACi) which is a promising potential anticancer drug. Toll-like receptor 4 (TLR4) expression is increased in PCa cells and HDACi alter TLR-inducible gene expressions.

AIMS

We aimed to evaluate the effects of NaBu on TLR4 mediating signaling pathways in two different PCa cells (DU-145 and LNCaP) for the first time.

SUBJECTS AND METHODS

The cytotoxic and apoptotic effects of NaBu were determined by the water-soluble tetrazolium salt (WST-1) and Annexin V-AO/PI assays, respectively. Subcellular localization of TLR4, interferon regulatory factor-3 (IRF3) and Nuclear factor kappa B proteins was evaluated by IF assay.

STATISTICAL ANALYSIS USED

All data were statistically analyzed by GraphPad Prism software (V60.1, CA). Obtained data were expressed in a mean ± standard deviation of the three repeated experiments. The differences between control and NaBu treated cells were compared by one-way-ANOVA. P < 0.05 value was considered statistically significant.

RESULTS

Our results showed that NaBu significantly inhibited the viability of PCa cells and increased the percentage of apoptotic cells. However, DU-145 cells were more sensitive to NaBu than LNCaP cells. Furthermore, NaBu can induce the cytoplasmic TLR4 and IRF3 expression in particularly DU-145 cells without affecting nuclear translocation of NF-kB in PCa cells.

CONCLUSIONS

NaBu induces apoptotic cell death and regulated the TLR4/IRF3 signaling pathways in DU-145 cells but not in LNCaP cells. Therefore, PCa cells differentially responded to NaBu treatment due to probably androgen receptor status.

Design, synthesis and biological evaluation of pyrimidine base hydroxamic acid derivatives as dual JMJD3 and HDAC inhibitors

The Jumonji domain-containing protein demethylase 3 (JMJD3) and histone deacetylase (HADC) are related to various cancers and regard as antitumor targets for drug discovery. In this study, based on rational drug design strategy, we designed and synthesized a series of pyrimidine derivatives with hydroxamic acid as novel dual JMJD3 and HDAC inhibitors for synergistic cancer treatment. Compound A5b exhibited inhibitory potency against JMJD3 and HDAC1/6 simultaneously and favorable cytotoxicity against human cancer cells such as A549 and U937. Furthermore, mechanistic studies showed that A5b treatment in A549 cells increased the hypermethylation of histone H3K27 and hyperacetylation of H3K9, suppressed clonogenicity, migration and invasion of cancer cells. Besides, A5b induced apoptosis via the cleavage of caspase-7 and PARP, and G1 cell cycle arrest via upregulated p21 expression. All these results suggested that A5b was the first dual inhibitor against JMJD3 and HDAC and can be a potential compound for cancer therapy.

Current Approaches to Epigenetic Therapy

Epigenetic therapy is a promising tool for the treatment of a wide range of diseases. Several fundamental epigenetic approaches have been proposed. Firstly, the use of small molecules as epigenetic effectors, as the most developed pharmacological method, has contributed to the introduction of a number of drugs into clinical practice. Secondly, various innovative epigenetic approaches based on dCas9 and the use of small non-coding RNAs as therapeutic agents are also under extensive research. In this review, we present the current state of research in the field of epigenetic therapy, considering the prospects for its application and possible limitations.

Bortezomib and Vorinostat Therapy as Maintenance Therapy Post-Autologous Transplant for Non-Hodgkin's Lymphoma Using R-BEAM or BEAM Transplant Conditioning Regimen

INTRODUCTION

The success of autologous stem cell transplantation (ASCT) for treating non-Hodgkin's lymphoma (NHL) is limited by its high relapse rates. To reduce the risk of relapse, additional maintenance therapy can be added post-transplant. In a non-transplant setting at the time of initiation of this study, both bortezomib and vorinostat had been studied alone or in combination for some NHL histology and showed some clinical activity. At our center, this combination therapy post-transplant for multiple myeloma showed acceptable toxicity. Therefore, it seemed reasonable to study this combination therapy post-ASCT for NHL.

METHODS

NHL patients underwent conditioning for ASCT with rituximab, carmustine, etoposide, cytarabine, melphalan/carmustine, etoposide, cytarabine, melphalan. After recovery from the acute transplant-related toxicity, combination therapy with IV bortezomib and oral vorinostat (BV) was started and was given for a total of 12 (28-day) cycles.

RESULTS

Nineteen patients received BV post-ASCT. The most common toxicities were hematologic, gastrointestinal, metabolic, fatigue, and peripheral neuropathy. With a median follow-up of 10.3 years, 11 patients (58%) are alive without disease progression and 12 patients (63%) are alive.

CONCLUSIONS

BV can be given post-ASCT for NHL and produces excellent disease-free and overall survival rates.

Discovery of Novel 1,2,3,4-Tetrahydrobenzofuro[2,3-c]pyridine Histone Deacetylase Inhibitors for Efficient Treatment of Hepatocellular Carcinoma

The development of histone deacetylase (HDAC) inhibitors for treating hematologic malignancies has been widely investigated, while their role in hepatocellular carcinoma (HCC) remains unexplored. In this study, we employed a scaffold-hopping design and a multicomponent synthesis approach to develop a novel series of 1,2,3,4-tetrahydrobenzofuro[2,3-c]pyridines as HDAC inhibitors. There were a total of 29 compounds achieved with flexible linkers and zinc-binding groups, wherein compound 12k was identified as a promising candidate with good HDAC inhibitory activity, pharmacokinetic profiles, and potency. It exhibited significant therapeutic efficacy in HCC cell lines (IC50 = 30 nM for Bel-7402) and xenograft models (76% inhibition for Bel-7402 xenografts, P.O. at 20 mg/kg, QOD, for 14 days) and was found to upregulate the acetylation of histone H3 and α-tubulin, leading to apoptosis and autophagy in HCC models. Molecular docking studies indicated a unique T-shaped conformation of 12k with the catalytic domain of HDAC1. Therefore, this work provides a new structure design for HDAC inhibitors and also offers a promising treatment for HCC.

Histone Modification of Colorectal Cancer by Natural Products

Natural products play important roles in the pathogenesis of many human malignancies, including colorectal cancer, and can act as a gene regulator in many cancers. They regulate malignant cell growth through many cellular signal pathways, including Rac family small GTPase 1 (RAC1)/PI3K/AKT (α-serine/threonine-protein kinase), mitogen-activated protein kinase (MAPK), Wnt/β-catenin pathway, transforming growth factor-β (TGF-β), Janus kinase and signal transducer and activator of transcription (JAK-STAT), nuclear factor kappa-B (NF-κB), the Notch pathway, Hippo pathway, and Hedgehog pathway. In this review, we describe the epigenetic roles of several natural products, e.g., platycodin D (PD), ginsenoside Rd, tretinoin, Rutin, curcumin, clove extract, betulinic acid, resveratrol, and curcumin, in colorectal cancer, including their impact on colorectal cancer cell proliferation, apoptosis, invasion, migration, and anti-chemotherapeutic resistance. The aim is to illustrate the epigenetic mechanisms of action of natural products in cancer prevention and treatment, and to provide (1) a theoretical basis for the study of the role of epigenetics in influencing colorectal cancer; (2) new directions for studying the occurrence, development, and prognosis of colorectal cancer; and (3) new targets for treating and preventing colorectal cancer.

Discovery of New Uracil and Thiouracil Derivatives as Potential HDAC Inhibitors

Background: Histone deacetylase inhibitors (HDACIs) are a relatively new class of potential drugs for treating cancer. Aim: Discovery of new anticancer agents targeting HDAC. Methods: New uracil and thiouracil derivatives panels were designed and synthesized as HDAC inhibitors. The synthesized compounds were tested against MCF-7, HepG2, and HCT-116. HDAC1 and HDAC4 inhibitory activities of these compounds were tested. The most active member was tested for its potential against cell cycle, apoptosis, caspase-3, and caspase-8. Docking studies were carried out against HDAC1. Results: Compounds 5a, 5b, 5f, 5i, 5k, and 5m exhibited promising cytotoxic activities. HDAC1 and HDAC4 inhibitory activities of these compounds were tested. Regarding the HDAC1 inhibitory activity, compound 5m was the most potent member (IC₅₀ = 0.05 µg/mL) compared to trichostatin A (IC₅₀ = 0.0349 µg/mL). For HDAC4, compound 5m showed superior activity (IC₅₀ = 2.83 µg/mL) than trichostatin A (IC₅₀ = 3.349 µg/mL). Compound 5m showed a high potential to arrest the HCT116 cell cycle at the G0-G1 phase. In addition, it showed an almost 17 times apoptotic effect (37.59%) compared to the control cells (2.17%). Furthermore, Compound 5m showed significant increases in the levels of caspase-3 and caspase-8. Finally, the uracil and thiouracil derivatives showed accepted binding mods against HDAC. Conclusions: Compound 5m has potential anticancer activity targeting HDAC with a significant apoptotic effect.

Perspectives and new aspects of histone deacetylase inhibitors in the therapy of CNS diseases

Many populations worldwide are suffering from central nervous system (CNS) diseases such as brain tumors, neurodegenerative diseases (Alzheimer's disease, Parkinson's disease and Huntington's disease) and stroke. There is a shortage of effective drugs for most CNS diseases. As one of the regulatory mechanisms of epigenetics, the particular role and therapeutic benefits of histone deacetylases (HDACs) in the CNS have been extensively studied. In recent years, HDACs have attracted increasing attention as potential drug targets for CNS diseases. In this review, we summarize the recent applications of representative histone deacetylases inhibitors (HDACis) in CNS diseases and discuss the challenges in developing HDACis with different structures and better blood-brain barrier (BBB) permeability, hoping to promote the development of more effective bioactive HDACis for the treatment of CNS diseases.

Yijung-tang improves thermogenesis and reduces inflammation associated with gut microbiota in hypothyroid rats

Currently, considerable attention is focused on exploring the potential relationship between herbal medicine (HM) and the gut microbiome in terms of thermoregulation, which is an important aspect of human health, in modern system biology. However, our knowledge of the mechanisms of HM in thermoregulation is inadequate. Here, we demonstrate that the canonical herbal formula, Yijung-tang (YJT), protects against hypothermia, hyperinflammation, and intestinal microbiota dysbiosis in PTU-induced hypothyroid rats. Notably, these properties were associated with alterations in the gut microbiota and signaling crosstalk between the thermoregulatory and inflammatory mediators in the small intestine and brown adipose tissue (BAT). In contrast to the conventional drug L-thyroxine for curing hypothyroidism, YJT has an efficacy for attenuating systematic inflammatory responses, related with depression in intestinal TLR4 and Nod2/Pglyrp1 signaling pathways. Our findings suggest that YJT could promote BAT thermogenesis and prevent systemic inflammation in PTU-induced hypothyroid rats, which was associated with its prebiotic effect on modulating of the gut microbiota and gene expression with relevance in the enteroendocrine function and innate immune systems. These findings may strengthen the rationale of the microbiota-gut-BAT axis for a paradigm shift to enable holobiont-centric medicine.

Dual targeted 2-Benzylideneindanone pendant hydroxamic acid group exhibits selective HDAC6 inhibition along with tubulin stabilization effect

Abnormal epigenetics has been recognised as an early event in tumour progression and aberrant acetylation of lysine in particular has been understood in tumorigenesis. Therefore, it has become an attractive target for anticancer drug development. However, HDAC inhibitors have limited success due to toxicity and drug resistance concerns. Present study deals with design and synthesis of bivalent indanone based HDAC6 and antitubulin ligands as anticancer agents. Two of the analogues 9 and 21 exhibited potent antiproliferative activities (IC₅₀, 0.36-3.27 µM) and high potency against HDAC 6 enzyme. Compound 21 showed high selectivity against HDAC 6 while 9 exhibited low selectivity. Both the compounds also showed microtubule stabilization effects and moderate anti-inflammatory effect. Dual targeted anticancer agents with concomitant anti-inflammatory effects will be more attractive clinical candidates in future.

Structural optimization of tetrahydroisoquinoline-hydroxamate hybrids as potent dual ERα degraders and HDAC inhibitors

Both estrogen receptor α (ERα) and histone deacetylases (HDACs) are valid therapeutic targets for anticancer drug development. Combination therapies using diverse ERα antagonists or degraders and HDAC inhibitors have been proven effective in endocrine-resistant ER + breast cancers based on the crosstalk between ERα and HDAC pathway. In this study, we reported the optimization of a series of methoxyphenyl- or pyridinyl- substituted tetrahydroisoquinoline-hydroxamates, which were optimized from 31, a dual ERα degrader/HDAC inhibitor previously reported by our group. Most of the synthesized compounds displayed potent ERα degradation efficacy and antiproliferative activity. Among them, A04 demonstrated the best anti-proliferation activity (MCF-7 IC₅₀ = 1.96 µM) and HDAC6 inhibitory activity (HDAC6 IC₅₀ = 25.96 nM), which is slightly more potent than the lead compound 31 (MCF-7 IC₅₀ = 4.38 μM, HDAC6 IC₅₀ = 63.03 nM). In addition, compound A04 exerted ERα-independent HDAC6-inhibiting effect without agonistic activity in endometrial cells. These results demonstrated that A04 is a novel and promising dual ERα degrader/HDAC inhibitor worthy of further development.

Inhibition of histone deacetylases attenuates tumor progression and improves immunotherapy in breast cancer

Breast cancer is one of the common malignancies with poor prognosis worldwide. The treatment of breast cancer patients includes surgery, radiation, hormone therapy, chemotherapy, targeted drug therapy and immunotherapy. In recent years, immunotherapy has potentiated the survival of certain breast cancer patients; however, primary resistance or acquired resistance attenuate the therapeutic outcomes. Histone acetyltransferases induce histone acetylation on lysine residues, which can be reversed by histone deacetylases (HDACs). Dysregulation of HDACs via mutation and abnormal expression contributes to tumorigenesis and tumor progression. Numerous HDAC inhibitors have been developed and exhibited the potent anti-tumor activity in a variety of cancers, including breast cancer. HDAC inhibitors ameliorated immunotherapeutic efficacy in cancer patients. In this review, we discuss the anti-tumor activity of HDAC inhibitors in breast cancer, including dacinostat, belinostat, abexinostat, mocetinotat, panobinostat, romidepsin, entinostat, vorinostat, pracinostat, tubastatin A, trichostatin A, and tucidinostat. Moreover, we uncover the mechanisms of HDAC inhibitors in improving immunotherapy in breast cancer. Furthermore, we highlight that HDAC inhibitors might be potent agents to potentiate immunotherapy in breast cancer.

Fatty acids as histone deacetylase inhibitors: old biochemistry tales in a new life sciences town

Histone acetylation is a key epigenetic event. Although the keywords fatty acids, histones, and histone acetylation have a long history in biochemistry, these topics continue to attract much attention among researchers. The acetylation of histones is controlled by the activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). An imbalance in the activities of HATs and HDACs is common in a range of human cancers. Histone deacetylase inhibitors (HDACi) can restore dysregulated histone acetylation profiles in cancer cells and have been identified as promising anti-cancer therapeutics. Short-chain fatty acids mediate anti-cancer effects by inhibiting the activity of HDACs. Recent studies have identified odd-chain fatty acids as novel HDACi. This review summarizes recent findings regarding fatty acids as HDACi in cancer therapy. Teaser: Inhibition of histone deacetylase (HDAC) activity by fatty acids.

Development of Alkylated Hydrazides as Highly Potent and Selective Class I Histone Deacetylase Inhibitors with T cell Modulatory Properties

Histone deacetylases (HDACs) are epigenetic regulators and additionally control the activity of non-histone substrates. We recently demonstrated that inhibition of HDAC8 overexpressed in various of cancers reduces hepatocellular carcinoma tumorigenicity in a T cell-dependent manner. Here, we present alkylated hydrazide-based class I HDAC inhibitors in which the n-hexyl side chain attached to the hydrazide moiety shows HDAC8 selectivity in vitro. Analysis of the mode of inhibition of the most promising compound 7d against HDAC8 revealed a substrate-competitive binding mode. 7d marked induced acetylation of the HDAC8 substrates H3K27 and SMC3 but not tubulin in CD4⁺ T lymphocytes, and significantly upregulated gene expressions for memory and effector functions. Furthermore, intraperitoneal injection of 7d (10 mg/kg) in C57BL/6 mice increased interleukin-2 expression in CD4⁺ T cells and CD8⁺ T cell proportion with no apparent toxicity. This study expands a novel chemotype of HDAC8 inhibitors with T cell modulatory properties for future therapeutic applications.

HDAC5 Loss Enhances Phospholipid-Derived Arachidonic Acid Generation and Confers Sensitivity to cPLA2 Inhibition in Pancreatic Cancer

HDAC5 is a class IIa histone deacetylase member that is downregulated in multiple solid tumors, including pancreatic cancer, and loss of HDAC5 is associated with unfavorable prognosis. In this study, assessment of The Cancer Genome Atlas pancreatic adenocarcinoma dataset revealed that expression of HDAC5 correlates negatively with arachidonic acid (AA) metabolism, which has been implicated in inflammatory responses and cancer progression. Nontargeted metabolomics analysis revealed that HDAC5 knockdown resulted in a significant increase in AA and its downstream metabolites, such as eicosanoids and prostaglandins. HDAC5 negatively regulated the expression of the gene encoding calcium-dependent phospholipase A2 (cPLA2), the key enzyme in the production of AA from phospholipids. Mechanistically, HDAC5 repressed cPLA2 expression via deacetylation of GATA1. HDAC5 knockdown in cancer cells enhanced sensitivity to genetic or pharmacologic inhibition of cPLA2 in vitro and in vivo. Fatty acid supplementation in the diet reversed the sensitivity of HDAC5-deficient tumors to cPLA2 inhibition. These data indicate that HDAC5 loss in pancreatic cancer results in the hyperacetylation of GATA1, enabling the upregulation of cPLA2, which contributes to overproduction of AA. Dietary management plus cPLA2-targeted therapy could serve as a viable strategy for treating HDAC5-deficient pancreatic cancer patients.

SIGNIFICANCE

The HDAC5-GATA1-cPLA2-AA signaling axis regulates sensitivity to fat restriction plus cPLA2 inhibition in pancreatic ductal adenocarcinoma, proposing dietary management as a feasible strategy for treating a subset of patients with pancreatic cancer.

The roles of histone modifications in tumorigenesis and associated inhibitors in cancer therapy

Histone modifications are key factors in chromatin packaging, and are responsible for gene regulation during cell fate determination and development. Abnormal alterations in histone modifications potentially affect the stability of the genome and disrupt gene expression patterns, leading to many diseases, including cancer. In recent years, mounting evidence has shown that various histone modifications altered by aberrantly expressed modifier enzymes contribute to tumor development and metastasis through the induction of epigenetic, transcriptional, and phenotypic changes. In this review, we will discuss the existing histone modifications, both well-studied and rare ones, and their roles in solid tumors and hematopoietic cancers, to identify the molecular pathways involved and investigate targeted therapeutic drugs to reorganize the chromatin and enhance cancer treatment efficiency. Finally, clinical inhibitors of histone modifications are summarized to better understand the developmental stage of cancer therapy in using these drugs to inhibit the histone modification enzymes.

Transcriptomic analysis reveals the key role of histone deacetylation via mediating different phytohormone signalings in fiber initiation of cotton

Background

Histone deacetylation is one of the most important epigenetic modifications and plays diverse roles in plant development. However, the detailed functions and mechanisms of histone deacetylation in fiber development of cotton are still unclear. HDAC inhibitors (HDACi) have been commonly used to study the molecular mechanism underlying histone deacetylation or to facilitate disease therapy in humans through hindering the histone deacetylase catalytic activity. Trichostatin A (TSA)—the most widely used HDACi has been extensively employed to determine the role of histone deacetylation on different developmental stages of plants.

Results

Through in vitro culture of ovules, we observed that exogenous application of TSA was able to inhibit the fiber initiation development. Subsequently, we performed a transcriptomic analysis to reveal the underlying mechanisms. The data showed that TSA treatment resulted in 4209 differentially expressed genes, which were mostly enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, photosynthesis, and carbon metabolism pathways. The phytohormone signal transduction pathways harbor the most differentially expressed genes. Deeper studies showed that some genes promoting auxin, Gibberellic Acid (GA) signaling were down-regulated, while some genes facilitating Abscisic Acid (ABA) and inhibiting Jasmonic Acid (JA) signaling were up-regulated after the TSA treatments. Further analysis of plant hormone contents proved that TSA significantly promoted the accumulation of ABA, JA and GA₃.

Conclusions

Collectively, histone deacetylation can regulate some key genes involved in different phytohormone pathways, and consequently promoting the auxin, GA, and JA signaling, whereas repressing the ABA synthesis and signaling to improve the fiber cell initiation. Moreover, the genes associated with energy metabolism, phenylpropanoid, and glutathione metabolism were also regulated by histone deacetylation. The above results provided novel clues to illuminate the underlying mechanisms of epigenetic modifications as well as related different phytohormones in fiber cell differentiation, which is also very valuable for the molecular breeding of higher quality cotton.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00840-4.

Discovery and SAR analysis of 5-chloro-4-((substituted phenyl)amino)pyrimidine bearing histone deacetylase inhibitors

Histone deacetylases (HDACs) are validated targets for the development of anticancer drugs in epigenetics. In the discovery of novel HDAC inhibitors with anticancer potency, the 5-chloro-4-((substituted phenyl)amino)pyrimidine fragment is assembled as a cap group into the structure of HDAC inhibitors. The SAR revealed that presence of small groups (such as methoxy substitution) is beneficial for the HDAC inhibitory activity. In the enzyme inhibitory selectivity test, compound L20 exhibited class I selectivity with IC₅₀ values of 0.684 µM (selectivity index of >1462), 2.548 µM (selectivity index of >392), and 0.217 µM (selectivity index of >4608) against HDAC1, HDAC2 and HDAC3 compared with potency against HDAC6 (IC₅₀ value of >1000 µM), respectively. In the antiproliferative assay, compound L20 showed both hematological and solid cancer inhibitory activities. In the flow cytometry, L20 promoted G0/G1 phase cell cycle arrest and apoptosis of K562 cells.

Fragment-Based Discovery of a Novel, Brain Penetrant, Orally Active HDAC2 Inhibitor

Fragment-based ligand discovery was successfully applied to histone deacetylase HDAC2. In addition to the anticipated hydroxamic acid- and benzamide-based fragment screening hits, a low affinity (∼1 mM) α-amino-amide zinc binding fragment was identified, as well as fragments binding to other regions of the catalytic site. This alternative zinc-binding fragment was further optimized, guided by the structural information from protein-ligand complex X-ray structures, into a sub-μM, brain penetrant, HDAC2 inhibitor (17) capable of modulating histone acetylation levels in vivo.

Epigenetic Aberrations and Targets in Peripheral T-Cell Lymphoma

Peripheral T cell lymphomas (PTCL) comprise a diverse group of aggressive T-cell and NK-cell lymphomas with many subtypes sharing same treatment algorithms despite having different pathobiology and responses to treatment. The molecular advances made in discovery of genetic mutations that disrupt epigenetic modulation in some subtypes of PTCL such as angioimmunoblastic T cell lymphoma and PTCL-not otherwise specified (NOS) may explain the poor outcomes and unsatisfactory responses to frontline line CHOP and CHOP-like therapy seen in this group of lymphomas. In this article, we address the main genetic mutations such as IDH2, TET2 and DNMT3A seen in PTCL and that disrupt the epigenetic modulation pathways, focusing on acetylation, deacetylation and methylation. Since therapeutic agents that target the disrupted epigenetic modulation pathways in PTCL may change treatment landscape in the near future, we will highlight the ones approved for treatment of refractory and/or relapsed PTCL and also the pivotal regimens being evaluated in clinical trials for treatment of frontline and refractory relapsed disease. We stress the importance of determining whether there is an association between the discussed genetic mutations and responses to the highlighted therapeutic agents such that treatments could be better tailored in patients with this kind of lymphoma with unmet needs.

Epigenetic engineering for optimal CAR-T cell therapy

Recent advancements in cancer immunotherapy, such as chimeric antigen receptor (CAR)-engineered T cell therapy and immune checkpoint therapy (ICT), have significantly improved the clinical outcomes of patients with several types of cancer. To broaden its applicability further and induce durable therapeutic efficacy, it is imperative to understand how antitumor T cells elicit cytotoxic functions, survive as memory T cells, or are impaired in their effector functions (exhausted) at the molecular level. T cell properties are regulated by their gene expression profiles, which are further controlled by epigenetic architectures, such as DNA methylation and histone modifications. Multiple studies have elucidated specific epigenetic genes associated with T-cell phenotypic changes. Conversely, exogenous modification of these key epigenetic factors can significantly alter T cell functions by extensively altering the transcription network, which can be applied in cancer immunotherapy by improving T cell persistence or augmenting effector functions. Since CAR-T cell therapy involves a genetic engineering step during the preparation of the infusion products, it would be a feasible strategy to additionally modulate specific epigenetic genes in CAR-T cells to improve their quality. Here, we review recent studies investigating how individual epigenetic factors play a crucial role in T-cell biology. We further discuss future directions to integrate these findings for optimal cancer immunotherapy.

HDAC inhibitors Panobinostat and Romidepsin enhance tax transcription in HTLV-1-infected cell lines and freshly isolated patients’ T-cells

The viral transactivator Tax plays a key role in HTLV-1 reactivation and de novo infection. Previous approaches focused on the histone deacetylase inhibitor (HDACi) Valproate as a latency-reversing agent to boost Tax expression and expose infected cells to the host’s immune response. However, following treatment with Valproate proviral load decreases in patients with HAM/TSP were only transient. Here, we hypothesize that other compounds, including more potent and selective HDACi, might prove superior to Valproate in manipulating Tax expression. Thus, a panel of HDACi (Vorinostat/SAHA/Zolinza, Panobinostat/LBH589/Farydak, Belinostat/PXD101/Beleodaq, Valproate, Entinostat/MS-275, Romidepsin/FK228/Istodax, and MC1568) was selected and tested for toxicity and potency in enhancing Tax expression. The impact of the compounds was evaluated in different model systems, including transiently transfected T-cells, chronically HTLV-1-infected T-cell lines, and freshly isolated PBMCs from HTLV-1 carriers ex vivo. We identified the pan-HDACi Panobinostat and class I HDACi Romidepsin as particularly potent agents at raising Tax expression. qRT-PCR analysis revealed that these inhibitors considerably boost tax and Tax-target gene transcription. However, despite this significant increase in tax transcription and histone acetylation, protein levels of Tax were only moderately enhanced. In conclusion, these data demonstrate the ability of Panobinostat and Romidepsin to manipulate Tax expression and provide a foundation for further research into eliminating latently infected cells. These findings also contribute to a better understanding of conditions limiting transcription and translation of viral gene products.

Engaging plasticity: Differentiation therapy in solid tumors

Cancer is a systemic heterogeneous disease that can undergo several rounds of latency and activation. Tumor progression evolves by increasing diversity, adaptation to signals from the microenvironment and escape mechanisms from therapy. These dynamic processes indicate necessity for cell plasticity. Epithelial-mesenchymal transition (EMT) plays a major role in facilitating cell plasticity in solid tumors by inducing dedifferentiation and cell type transitions. These two practices, plasticity and dedifferentiation enhance tumor heterogeneity creating a key challenge in cancer treatment. In this review we will explore cancer cell plasticity and elaborate treatment modalities that aspire to overcome such dynamic processes in solid tumors. We will further discuss the therapeutic potential of utilizing enhanced cell plasticity for differentiation therapy.

MBD1/HDAC3-miR-5701-FGFR2 axis promotes the development of gastric cancer

Gastric cancer (GC) remains one of the leading causes of cancer-related deaths worldwide due to the lack of specific biomarkers for the early diagnosis and universal accepted therapy for advanced GC. Lower levels of miR-5701 were found in the GC tissue from the online sequencing data and confirmed in the GC tissues and GC cell lines. Overexpression of miR-5701 inhibited the proliferation and migration of GC cells and promoted the apoptosis of these cells. Bioinformatics analyses and luciferase assay showed that miR-5701 targeted FGFR2, which acted as an oncogene in GC. Nude mice with GC cells overexpressing miR-5701 exhibited smaller tumor sizes and less lung metastases. The miR-5701 expression was directly, transcriptionally inhibited by MBD1 together with HDAC3 by binding together to form a complex. Knocked down MBD1 or HDAC3 increased the miR-5701 expression. These results indicated the potential use of exogenously administered miR-5701 or agents that elevated endogenous miR-5701 to inhibit GC, improving the prognosis of patients with GC.

Exploring the mechanism of Qinbaiqingfei-concentrate pills in the treatment of Mycoplasma pneumoniae pneumonia from the perspective of intestinal microbiota and mucosal immunity

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine categorizes Mycoplasma pneumoniae pneumonia as "lung heat", and treatment with heat clear and detoxify. Traditional Chinese medicine believes that the lungs and intestines come from the same source, and the intestine is related to pneumonia. This is the same as the gut-lung axis theory. Qinbaiqingfei concentrate pills (QBs) were modified based on Cough San in the ancient medical book Medical Awareness. It clears lung heat, moisturizes the lungs and dredges collaterals, and has a good ability to treat Mycoplasma pneumoniae.

AIM OF THE STUDY

A rat model of Mycoplasma pneumoniae was established. From the aspect of intestinal flora and mucosal immunity, the potential mechanism of the QBs was researched.

MATERIALS AND METHODS

First, the content of Mycoplasma pneumoniae in lung tissue and the levels of the inflammatory factors IL-4, IL-10, TNF-α and INF-γ were detected. To determine the expression of NF-kB related proteins in lung tissue, which can understand the ability in treating disease. Next, metagenomic sequencing was performed to detect changes in short-chain fatty acids, proving the ability of the drug to regulate intestinal microecology. Finally, HDAC, LPS, SIgA, etc. were detected to facilitate the correlation of the overall experimental indicators.

RESULTS

QBs reduces the levels of IL-4, IL-10, TNF-α and INF-γ in the serum by inhibiting the expression of MyD88, IKKα, IκBα, and NF-κB p65 in lung tissue. In addition, QBs restores the ratio of gram-negative bacteria to gram-positive bacteria in the intestine, restores the secretion of acetic acid, propionic acid, butyric acid, isobutyric acid and isovaleric acid, and promotes the secretion of NF-κB p65 and SIgA by HDAC1/3. The result is that the lung tissue is repaired and the proliferation of Mycoplasma pneumoniae is inhibited.

CONCLUSIONS

From the "gut-lung axis", a new research perspective was discovered. QBs intervened in the intestines and lungs to treat Mycoplasma pneumoniae.

Discovery of 2-Phenylquinoline-4-Carboxylic Acid Derivatives as Novel Histone Deacetylase Inhibitors

Inhibition of histone deacetylases (HDACs) has been extensively studied in the development of anticancer drugs. In the discovery of potent HDAC inhibitors with novel structures, the 2-substituted phenylquinoline-4-carboxylic acid group was introduced to the cap moiety of HDAC inhibitors. In total, 30 compounds were synthesized with hydroxamic acid or hydrazide zinc-binding groups. In the enzyme inhibitory test, active compound D28 and its analog D29 exhibited significant HDAC3 selectivity against HDAC1, 2, 3, and 6. However, compared with D28, the hydrazide-bearing compounds (D29 and D30) with remarkably improved enzyme inhibitory activities did not exhibit significant antiproliferative potency in the in vitro anticancer study. Further K562 cell-based mechanistic results revealed that induction of G2/M cell cycle arrest and promotion of apoptosis make important contributions to the anticancer effects of molecule D28. Collectively, an HDAC3 selective inhibitor (D28) with potent in vitro anticancer activity was developed as a lead compound for the treatment of cancer.

Dihydropyrazole-Carbohydrazide Derivatives with Dual Activity as Antioxidant and Anti-Proliferative Drugs on Breast Cancer Targeting the HDAC6

Breast cancer (BC) is the most frequently diagnosed cancer and is the second-most common cause of death in women worldwide. Because of this, the search for new drugs and targeted therapy to treat BC is an urgent and global need. Histone deacetylase 6 (HDAC6) is a promising anti-BC drug target associated with its development and progression. In the present work, the design and synthesis of a new family of dihydropyrazole-carbohydrazide derivatives (DPCH) derivatives focused on HDAC6 inhibitory activity is presented. Computational chemistry approaches were employed to rationalize the design and evaluate their physicochemical and toxic-biological properties. The new family of nine DPCH was synthesized and characterized. Compounds exhibited optimal physicochemical and toxicobiological properties for potential application as drugs to be used in humans. The in silico studies showed that compounds with –Br, –Cl, and –OH substituents had good affinity with the catalytic domain 2 of HDAC6 like the reference compounds. Nine DPCH derivatives were assayed on MCF-7 and MDA-MB-231 BC cell lines, showing antiproliferative activity with IC₅₀ at μM range. Compound 2b showed, in vitro, an IC₅₀ value of 12 ± 3 µM on human HDAC6. The antioxidant activity of DPCH derivatives showed that all the compounds exhibit antioxidant activity similar to that of ascorbic acid. In conclusion, the DPCH derivatives are promising drugs with therapeutic potential for the epigenetic treatment of BC, with low cytotoxicity towards healthy cells and important antioxidant activity.

The Histone Deacetylase Inhibitor I13 Induces Differentiation of M2, M3 and M5 Subtypes of Acute Myeloid Leukemia Cells and Leukemic Stem-Like Cells

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by reduced differentiation of myeloid cells and uncontrolled cell proliferation. AML is prone to drug resistance and has a high recurrence rate during treatment with cytarabine-based chemotherapy. Our study aims to explore the cell differentiation effect of a potent histone deacetylase inhibitor (HDACi), I13, and its possible mechanism on AML cell lines (Kasumi-1, KG-1, MOLM-13 and NB4). It has been shown that I13 can significantly inhibit proliferation and colony formation of these AML cells by inducing cell differentiation coupled with cell-cycle exit at G0/G1. Mechanically, I13 presented the property of HDAC inhibition, as assessed by the acetylation of histone H3, which led to the differentiation of Kasumi-1 cells. In addition, the HDAC inhibition of I13 likely dictated the activation of the antigen processing and presentation pathway, which maybe has the potential to promote immune cells to recognize leukemic cells and respond directly against leukemic cells. These results indicated that I13 could induce differentiation of M3 and M5 subtypes of AML cells, M2 subtype AML cells with t(8;21) translocation and leukemic stem-like cells. Therefore, I13 could be an alternative compound which is able to overcome differentiation blocks in AML.

Lysine Acetylation/Deacetylation Modification of Immune-Related Molecules in Cancer Immunotherapy

As major post-translational modifications (PTMs), acetylation and deacetylation are significant factors in signal transmission and cellular metabolism, and are modulated by a dynamic process via two pivotal categories of enzymes, histone acetyltransferases (HATs) and histone deacetylases (HDACs). In previous studies, dysregulation of lysine acetylation and deacetylation has been reported to be associated with the genesis and development of malignancy. Scientists have recently explored acetylation/deacetylation patterns and prospective cancer therapy techniques, and the FDA has approved four HDAC inhibitors (HDACi) to be used in clinical treatment. In the present review, the most recent developments in the area of lysine acetylation/deacetylation alteration in cancer immunotherapy were investigated. Firstly, a brief explanation of the acetylation/deacetylation process and relevant indispensable enzymes that participate therein is provided. Subsequently, a multitude of specific immune-related molecules involved in the lysine acetylation/deacetylation process are listed in the context of cancer, in addition to several therapeutic strategies associated with lysine acetylation/deacetylation modification in cancer immunotherapy. Finally, a number of prospective research fields related to cancer immunotherapy concepts are offered with detailed analysis. Overall, the present review may provide a reference for researchers in the relevant field of study, with the aim of being instructive and meaningful to further research as well as the selection of potential targets and effective measures for future cancer immunotherapy strategies.

Design, Synthesis, and Evaluation of Benzoheterocyclic-Containing Derivatives as Novel HDAC1 Inhibitors

In this study, the synthesis and biological evaluation of a variety of benzoheterocyclic-containing benzamide derivatives were described. Some of these compounds were proved to inhibiting the activity of histone deacetylase 1 (HDAC1) with IC50 values below the micromolar range, retarding proliferation of several human cancer cells, and surprisingly, not possessing toxicity to human normal cells and hERG K+ ion channels. Among those compounds, 3c was the most potent and efficacious derivative. Compound 3c was orally active and displayed excellent in vivo antitumor activity in a HCT-116 xenograft mice model.

Evodiamine-Inspired Topoisomerase-Histone Deacetylase Dual Inhibitors: Novel Orally Active Antitumor Agents for Leukemia Therapy

On the basis of the synergism of topoisomerase (Top) and histone deacetylase (HDAC) inhibitors in antitumor therapy, a series of novel Top/HDAC dual inhibitors were designed and synthesized by the pharmacophore fusion strategy. After systematic structure-activity relationship studies, lead compound 16j was identified to simultaneously inhibit both Top and HDAC with good potency, which showed potent antiproliferative activities with a broad spectrum. Mechanistic studies indicated that compound 16j efficiently induced apoptosis with S cell-cycle arrest in HEL cancer cells. It was orally active in HEL xenograft models and exhibited excellent in vivo antitumor efficacy (TGI = 68.5%; 10 mg/kg). Altogether, this work highlights the therapeutic potential of evodiamine-inspired Top/HDAC dual inhibitors and provides a valuable lead compound for the development of novel antitumor agents for leukemia therapy.