The safety profile of vorinostat (suberoylanilide hydroxamic acid) in hematologic malignancies: A review of clinical studies

Discovery of Novel Imidazo[1,2-a]pyridine-Based HDAC6 Inhibitors as an Anticarcinogen with a Cardioprotective Effect

Cardiotoxicity associated with chemotherapy has gradually become the major cause of death in cancer patients. The development of bifunctional drugs with both cardioprotective and antitumor effects has become the future direction. HDAC6 plays important roles in the progression, treatment, and prognosis of cancer and cardiovascular diseases, but bifunctional inhibitors have not been reported. Herein, structure-activity relationship studies driven by pharmacophore-based remodification and fragment-based design were performed to yield highly potent HDAC6 inhibitor I-c4 containing imidazo[1,2-a]pyridine. Importantly, I-c4 effectively suppressed the growth of MGC-803 xenografts in vitro and in vivo by inhibiting the deacetylation pathway without causing myocardial damage after long-term administration. Meanwhile, I-c4 could mitigate severe myocardial damage against H2O2 or myocardial ischemia/reperfusion in vitro and in vivo. Further studies revealed that the cardioprotective effect of I-c4 was associated with reduction of inflammatory cytokines. Taken together, I-c4 may represent a novel lead compound for further development of an anticarcinogen with a cardioprotective effect.

Long-range action of an HDAC inhibitor treats chronic pain in a spared nerve injury rat model

Histone deacetylase inhibitors (HDACi) that modulate epigenetic regulation and are approved for treating rare cancers have, in disease models, also been shown to mitigate neurological conditions, including chronic pain. They are of interest as non-opioid treatments, but achieving long-term efficacy with limited dosing has remained elusive. Here we utilize a triple combination formulation (TCF) comprised of a pan-HDACi vorinostat (Vo at its FDA-approved daily dose of 50mg/Kg), the caging agent 2-hydroxypropyl-β-cyclodextrin (HPBCD) and polyethylene glycol (PEG) known to boost plasma and brain exposure and efficacy of Vo in mice and rats, of various ages, spared nerve injury (SNI) model of chronic neuropathic pain. Administration of the TCF (but not HPBCD and PEG) decreased mechanical allodynia for 4 weeks without antagonizing weight, anxiety, or mobility. This was achieved at less than 1% of the total dose of Vo approved for 4 weeks of tumor treatment and associated with decreased levels of major inflammatory markers and microglia in ipsilateral (but not contralateral) spinal cord regions. A single TCF injection was sufficient for 3-4 weeks of efficacy: this was mirrored in repeat injections, specific for the injured paw and not seen on sham treatment. Pharmacodynamics in an SNI mouse model suggested pain relief was sustained for days to weeks after Vo elimination. Doubling Vo in a single TCF injection proved effectiveness was limited to male rats, where the response amplitude tripled and remained effective for > 2 months, an efficacy that outperforms all currently available chronic pain pharmacotherapies. Together, these data suggest that through pharmacological modulation of Vo, the TCF enables single-dose effectiveness with extended action, reduces long-term HDACi dosage, and presents excellent potential to develop as a non-opioid treatment option for chronic pain.

MicroRNA-Mediated Regulation of Histone-Modifying Enzymes in Cancer: Mechanisms and Therapeutic Implications

In the past decade, significant advances in molecular research have provided a deeper understanding of the intricate regulatory mechanisms involved in carcinogenesis. MicroRNAs, short non-coding RNA sequences, exert substantial influence on gene expression by repressing translation or inducing mRNA degradation. In the context of cancer, miRNA dysregulation is prevalent and closely associated with various stages of carcinogenesis, including initiation, progression, and metastasis. One crucial aspect of the cancer phenotype is the activity of histone-modifying enzymes that govern chromatin accessibility for transcription factors, thus impacting gene expression. Recent studies have revealed that miRNAs play a significant role in modulating these histone-modifying enzymes, leading to significant implications for genes related to proliferation, differentiation, and apoptosis in cancer cells. This article provides an overview of current research on the mechanisms by which miRNAs regulate the activity of histone-modifying enzymes in the context of cancer. Both direct and indirect mechanisms through which miRNAs influence enzyme expression are discussed. Additionally, potential therapeutic implications arising from miRNA manipulation to selectively impact histone-modifying enzyme activity are presented. The insights from this analysis hold significant therapeutic promise, suggesting the utility of miRNAs as tools for the precise regulation of chromatin-related processes and gene expression. A contemporary focus on molecular regulatory mechanisms opens therapeutic pathways that can effectively influence the control of tumor cell growth and dissemination.

Potential of Synthetic and Natural Compounds as Novel Histone Deacetylase Inhibitors for the Treatment of Hematological Malignancies

Histone deacetylases (HDACs) and histone acetyltransferases (HATs) are enzymes that remove or add acetyl groups to lysine residues of histones, respectively. Histone deacetylation causes DNA to more snugly encircle histones and decreases gene expression, whereas acetylation has the opposite effect. Through these small alterations in chemical structure, HATs and HDACs regulate DNA expression. Recent research indicates histone deacetylase inhibitors (HDACis) may be used to treat malignancies, including leukemia, B-cell lymphoma, virus-associated tumors, and multiple myeloma. These data suggest that HDACis may boost the production of immune-related molecules, resulting in the growth of CD8-positive T-cells and the recognition of nonreactive tumor cells by the immune system, thereby diminishing tumor immunity. The argument for employing epigenetic drugs in the treatment of acute myeloid leukemia (AML) patients is supported by evidence that both epigenetic changes and mutations in the epigenetic machinery contribute to AML etiology. Although hypomethylating drugs have been licensed for use in AML, additional epigenetic inhibitors, such as HDACis, are now being tested in humans. Preclinical studies evaluating the efficacy of HDACis against AML have shown the ability of specific agents, such as anobinostat, vorinostat, and tricostatin A, to induce growth arrest, apoptosis, autophagy and cell death. However, these inhibitors do not seem to be successful as monotherapies, but instead achieve results when used in conjunction with other medications. In this article, we discuss the mounting evidence that HDACis promote extensive histone acetylation, as well as substantial increases in reactive oxygen species and DNA damage in hematological malignant cells. We also evaluate the potential of various natural product-based HDACis as therapeutic agents to combat hematological malignancies.

Differential Response of Mycosis Fungoides Cells to Vorinostat

Mycosis fungoides (MF) is the most common form of cutaneous T-cell lymphoma (CTCL) and is characterized by epidermotrophism of malignant CD4+ T-lymphocytes. When MF advances to a recurrent stage, patients require treatment with systemic therapies such as vorinostat, a histone deacetylase inhibitor. While vorinostat has been shown to exhibit anti-tumor activity in MF, its exact molecular mechanism has yet to be fully discerned. In the present study, we examined the transcriptomic and proteomic profiles of vorinostat treatment in two MF cell lines, Myla 2059 and HH. We find that vorinostat downregulates CTLA-4, CXCR4, and CCR7 in both cell lines, but its effect on several key pathways differs between the two MF cell lines. For example, vorinostat upregulates CCL5, CCR5, and CXCL10 expression in Myla cells but downregulates CCL5 and CXCL10 expression in HH cells. Furthermore, vorinostat upregulates IFN-γ and IL-23 signaling and downregulates IL-6, IL-7, and IL-15 signaling in Myla cells but does not affect these pathways in HH cells. Although Myla and HH represent established MF cell lines, their distinct tumor origin from separate patients demonstrates that inherent phenotypic variations within the disease persist, underscoring the importance of using a variety of MF cells in the preclinical development of MF therapeutics.

Enabling Single-Cell Drug Response Annotations from Bulk RNA-Seq Using SCAD

The single-cell RNA sequencing (scRNA-seq) quantifies the gene expression of individual cells, while the bulk RNA sequencing (bulk RNA-seq) characterizes the mixed transcriptome of cells. The inference of drug sensitivities for individual cells can provide new insights to understand the mechanism of anti-cancer response heterogeneity and drug resistance at the cellular resolution. However, pharmacogenomic information related to their corresponding scRNA-Seq is often limited. Therefore, a transfer learning model is proposed to infer the drug sensitivities at single-cell level. This framework learns bulk transcriptome profiles and pharmacogenomics information from population cell lines in a large public dataset and transfers the knowledge to infer drug efficacy of individual cells. The results suggest that it is suitable to learn knowledge from pre-clinical cell lines to infer pre-existing cell subpopulations with different drug sensitivities prior to drug exposure. In addition, the model offers a new perspective on drug combinations. It is observed that drug-resistant subpopulation can be sensitive to other drugs (e.g., a subset of JHU006 is Vorinostat-resistant while Gefitinib-sensitive); such finding corroborates the previously reported drug combination (Gefitinib + Vorinostat) strategy in several cancer types. The identified drug sensitivity biomarkers reveal insights into the tumor heterogeneity and treatment at cellular resolution.

Design and Synthesis of Triazole-Containing HDAC Inhibitors That Induce Antitumor Effects and Immune Response

Histone deacetylase (HDAC) is an epigenetic antitumor drug target, but most existing HDAC inhibitors show limited antitumor activity and their use is often accompanied by serious adverse effects. To overcome these problems, we designed and synthesized a series of triazole-containing compounds as novel HDAC inhibitors. Among them, compound 19h exhibited potent and selective inhibition of HDAC1, with good antiproliferative activity in vitro and an excellent pharmacokinetic profile. Compound 19h significantly inhibited the growth of human tumor xenografts in nude mice and murine tumor growth in immune-competent mice bearing MC38 colon cancer. In the MC38 model, 19h increased the ratio of splenic CD4⁺ T effector cells and promoted complete tumor regression in 5/6 animals when combined with the mPD-1 antibody. These results suggested that selective class I HDAC inhibitors exert direct tumor growth inhibition and indirect immune cell-mediated antitumor effects and are synergistic with immune checkpoint inhibitors.

Are the epigenetic changes predictive of therapeutic efficacy for psychiatric disorders? A translational approach towards novel drug targets

The etiopathogenesis of mental disorders is not fully understood and accumulating evidence support that clinical symptomatology cannot be assigned to a single gene mutation, but it involves several genetic factors. More specifically, a tight association between genes and environmental risk factors, which could be mediated by epigenetic mechanisms, may play a role in the development of mental disorders. Several data suggest that epigenetic modifications such as DNA methylation, post-translational histone modification and interference of microRNA (miRNA) or long non-coding RNA (lncRNA) may modify the severity of the disease and the outcome of the therapy. Indeed, the study of these mechanisms may help to identify patients particularly vulnerable to mental disorders and may have potential utility as biomarkers to facilitate diagnosis and treatment of psychiatric disorders. This article summarizes the most relevant preclinical and human data showing how epigenetic modifications can be central to the therapeutic efficacy of antidepressant and/or antipsychotic agents, as possible predictor of drugs response.

Ibrutinib combined with low-dose histone deacetylases inhibitor chidamide synergistically enhances the anti-tumor effect in B-cell lymphoma

Aberrant activity of histone deacetylases (HDACs) is frequently detected in B-cell lymphomas, which indicated the therapeutic implications of HDAC inhibitors for B-cell malignancies. We have discovered that lymphoma cells treated with HDAC inhibitor presented with activation of Bruton tyrosine kinase (BTK) which played an important role in the development of B-cell malignancies. Therefore, our study intended to explore whether the addition of ibrutinib (BTK inhibitor) to chidamide (HDAC inhibitor) could generate combined anti-tumor effects in B-cell lymphomas. Using cell viability assay, cell cycle and apoptosis kit, we demonstrated an evident synergistic action of ibrutinib and chidamide in inhibiting tumor cell proliferation and motility. Consistent with in vitro data, the synergistic anti-tumor effects were also observed in multiple tumor-bearing mice models. By performing RNA-seq and flow cytometry of tumor tissue, the enhancement of anti-tumor immunity was observed with the co-treatment of chidamide and ibrutinib. Together, these mechanistic insights indicated that simultaneously targeting BTK and HDAC could be a promising clinical therapy for B-cell lymphomas.

The histone deacetylase SIRT6 promotes glycolysis through the HIF-1α/HK2 signaling axis and induces erlotinib resistance in non-small cell lung cancer

Erlotinib is a first-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). Overcoming erlotinib resistance is crucial to improve the survival of advanced non-small cell lung cancer (NSCLC) patients with sensitive EGFR mutations. It is also an important clinical problem that urgently needs a solution. In this study, we explored strategies to overcome erlotinib resistance from the perspective of energy metabolism. SIRT6 is a histone deacetylase. Here, we found that high expression of SIRT6 is associated with poor prognosis of lung adenocarcinoma, especially in EGFR-mutated NSCLC patients. The next cell experiment found that SIRT6 expression increased in erlotinib-resistant cells, and SIRT6 expression was negatively correlated with the sensitivity of NSCLC to erlotinib. Inhibition of SIRT6 promoted erlotinib-induced apoptosis in erlotinib-resistant cells, and glycolysis in drug-resistant cells was also inhibited. Functional studies have shown that SIRT6 increases glycolysis through the HIF-1α/HK2 signaling axis in drug-resistant cells and inhibits the sensitivity of NSCLC cells to erlotinib. In addition, the HIF-1α blocker PX478-2HCL attenuated the glycolysis and erlotinib resistance induced by SIRT6. More importantly, we confirmed the antitumor effect of SIRT6 inhibition combined with erlotinib in NSCLC-bearing mice. Our findings indicate that the cancer metabolic pathway regulated by SIRT6 may be a new target for attenuating NSCLC erlotinib resistance and has potential as a biomarker or therapeutic target to improve outcomes in NSCLC patients.

Suberoylanilide hydroxamic acid suppresses axonal damage and neurological dysfunction after subarachnoid hemorrhage via the HDAC1/HSP70/TDP-43 axis

Increased focus has been placed on the role of histone deacetylase inhibitors as crucial players in subarachnoid hemorrhage (SAH) progression. Therefore, this study was designed to expand the understanding of SAH by exploring the downstream mechanism of the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) in SAH. The expression of TDP-43 in patients with SAH and rat models of SAH was measured. Then, western blot analysis, immunofluorescence staining, and transmission electron microscope were used to investigate the in vitro effect of TDP-43 on a neuronal cell model of SAH established by oxyhemoglobin treatment. Immunofluorescence staining and coimmunoprecipitation assays were conducted to explore the relationship among histone deacetylase 1 (HDAC1), heat shock protein 70 (HSP70), and TDP-43. Furthermore, the in vivo effect of HDAC1 on SAH was investigated in rat models of SAH established by endovascular perforation. High expression of TDP-43 in the cerebrospinal fluid of patients with SAH and brain tissues of rat models of SAH was observed, and TDP-43 accumulation in the cytoplasm and the formation of inclusion bodies were responsible for axonal damage, abnormal nuclear membrane morphology, and apoptosis in neurons. TDP-43 degradation was promoted by the HDAC1 inhibitor SAHA via the acetylation of HSP70, alleviating SAH, and this effect was verified in vivo in rat models. In conclusion, SAHA relieved axonal damage and neurological dysfunction after SAH via the HSP70 acetylation-induced degradation of TDP-43, highlighting a novel therapeutic target for SAH.

The anti-inflammatory mechanism of SAHA in acute pancreatitis through HDAC5/SLIT2/Akt/β-catenin axis

Acute pancreatitis (AP) is widely recognized to be an inflammation-related disease, in which HDAC was upregulated. The anti-inflammatory role of suberoylanilide hydroxamic acid (SAHA), a HDAC inhibitor, has been documented. In this context, this research was implemented to figure out whether SAHA manipulated inflammation in AP. Subsequent to induction of AP mouse model, HDAC5 expression was detected. The binding of HDAC5 and SLIT2 was detected by Co-Immunoprecipitation and ChIP assays. SAHA treatment and gain- and loss-of-function approaches were used in AP mice and lipopolysaccharide (LPS)-induced pancreatic acinar cells. In mice, biochemical methods were implemented to measure activities of pancreatic lipase, trypsin, MPO and pancreatic edema, TUNEL staining to determine pancreatic cell apoptosis, and flow cytometry to assess the total number of leukocytes and neutrophils in pancreas. In pancreatic acinar cells, CCK-8 was performed to evaluate cell viability. HDAC5 exhibited overexpression in AP mice. Mechanical analysis showed that HDAC5 facilitated SLIT2 deacetylation to downregulate SLIT2, thus activating Akt/β-catenin pathway in pancreatic acinar cells. SAHA treatment, HDAC5 silencing, or SLIT2 overexpression diminished inflammation in AP in vivo and in vitro. SAHA treatment, HDAC5 silencing, or SLIT2 overexpression reduced activities of pancreatic lipase, trypsin, MPO, pancreatic edema, and cell apoptosis in AP mice as well as elevated viability of LPS-induced pancreatic acinar cells. SAHA might exert anti-inflammatory effects in AP mice via HDAC5/SLIT2/Akt/β-catenin axis.

Redox-sensitive iodinated polymersomes carrying histone deacetylase inhibitor as a dual-functional nano-radiosensitizer for enhanced radiotherapy of breast cancer

Radiotherapy (RT) is a frequently used means in clinical tumor treatment. The outcome of RT varies, however, to a great extent, due to RT resistance or intolerable dose, which might be resolved by the development of radio-sensitizing strategies. Here, we report redox-sensitive iodinated polymersomes (RIP) carrying histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA, vorinostat), as a new dual-functional nano-radiosensitizer for breast cancer radiotherapy. SAHA-loaded RIP (RIP-SAHA) with a size of about 101 nm exhibited good colloidal stability while the reduction-activated release of SAHA, giving rise to better antitumor effect to 4T1 breast carcinoma cells than free SAHA. Accordingly, RIP-SAHA combined with a 4 Gy dose of X-ray radiation led to significantly enhanced suppression of 4T1 cells compared with SAHA combined 4 Gy of X-ray radiation, as a result of enhanced DNA damage and impeded DNA damage repair. The pharmacokinetics and biodistribution studies by single-photon emission computed tomography (SPECT) with ¹²⁵I-labeled SAHA (¹²⁵I-SAHA) showed a 17.3-fold longer circulation and 237.7-fold better tumor accumulation of RIP-SAHA over SAHA. The systemic administration of RIP-SAHA greatly sensitized radiotherapy of subcutaneous 4T1 breast tumors and brought about significant inhibition of tumor growth, without causing damages to major organs, compared with radiotherapy alone. RIP not only enhanced SAHA delivery but also acted as a radiosensitizer. RIP-SAHA emerges as a smart dual-functional nano-radiosensitizer to effectively enhance tumor radiotherapy.

Identification of Core Genes Related to Progression and Prognosis of Hepatocellular Carcinoma and Small-Molecule Drug Predication

Background

Hepatocellular carcinoma (HCC) is one of the most leading causes of cancer death with a poor prognosis. However, the underlying molecular mechanisms are largely unclear, and effective treatment for it is limited. Using an integrated bioinformatics method, the present study aimed to identify the key candidate prognostic genes that are involved in HCC development and identify small-molecule drugs with treatment potential.

Methods and Results

In this study, by using three expression profile datasets from Gene Expression Omnibus database, 1,704 differentially expressed genes were identified, including 671 upregulated and 1,033 downregulated genes. Then, weighted co-expression network analysis revealed nine modules are related with pathological stage; turquoise module was the most associated module. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway analyses (KEGG) indicated that these genes were enriched in cell division, cell cycle, and metabolic related pathways. Furthermore, by analyzing the turquoise module, 22 genes were identified as hub genes. Based on HCC data from gene expression profiling interactive analysis (GEPIA) database, nine genes associated with progression and prognosis of HCC were screened, including ANLN, BIRC5, BUB1B, CDC20, CDCA5, CDK1, NCAPG, NEK2, and TOP2A. According to the Human Protein Atlas and the Oncomine database, these genes were highly upregulated in HCC tumor samples. Moreover, multivariate Cox regression analysis showed that the risk score based on the gene expression signature of these nine genes was an independent prognostic factor for overall survival and disease-free survival in HCC patients. In addition, the candidate small-molecule drugs for HCC were identified by the CMap database.

Conclusion

In conclusion, the nine key gene signatures related to HCC progression and prognosis were identified and validated. The cell cycle pathway was the core pathway enriched with these key genes. Moreover, several candidate molecule drugs were identified, providing insights into novel therapeutic approaches for HCC.

Epigenetic regulation of inflammation in periodontitis: cellular mechanisms and therapeutic potential

Epigenetic mechanisms, namely DNA and histone modifications, are critical regulators of immunity and inflammation which have emerged as potential targets for immunomodulating therapies. The prevalence and significant morbidity of periodontitis, in combination with accumulating evidence that genetic, environmental and lifestyle factors cannot fully explain the susceptibility of individuals to disease development, have driven interest in epigenetic regulation as an important factor in periodontitis pathogenesis. Aberrant promoter methylation profiles of genes involved in inflammatory activation, including TLR2, PTGS2, IFNG, IL6, IL8, and TNF, have been observed in the gingival tissue, peripheral blood or buccal mucosa from patients with periodontitis, correlating with changes in expression and disease severity. The expression of enzymes that regulate histone acetylation, in particular histone deacetylases (HDACs), is also dysregulated in periodontitis-affected gingival tissue. Infection of gingival epithelial cells, gingival fibroblasts and periodontal ligament cells with the oral pathogens Porphyromonas gingivalis or Treponema denticola induces alterations in expression and activity of chromatin-modifying enzymes, as well as site-specific and global changes in DNA methylation profiles and in histone acetylation and methylation marks. These epigenetic changes are associated with excessive production of inflammatory cytokines, chemokines, and matrix-degrading enzymes that can be suppressed by small molecule inhibitors of HDACs (HDACi) or DNA methyltransferases. HDACi and inhibitors of bromodomain-containing BET proteins ameliorate inflammation, osteoclastogenesis, and alveolar bone resorption in animal models of periodontitis, suggesting their clinical potential as host modulation therapeutic agents. However, broader application of epigenomic methods will be required to create a comprehensive map of epigenetic changes in periodontitis. The integration of functional studies with global analyses of the epigenetic landscape will provide critical information on the therapeutic and diagnostic potential of epigenetics in periodontal disease.

Expression of the Neural REST/NRSF-SIN3 Transcriptional Corepressor Complex as a Target for Small-Molecule Inhibitors

The repressor element 1 (RE1) silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) modulates the expression of genes with RE1/neuron-restrictive silencing element (RE1/NRSE) sites by recruiting the switch independent 3 (SIN3) factor and the REST corepressor (COREST) to its N and C-terminal repressor domain, respectively. Both, SIN3 and COREST assemble into protein complexes that are composed of multiple subunits including a druggable histone deacetylase (HDAC) enzyme. The SIN3 core complex comprises the eponymous proteins SIN3A or SIN3B, the catalytically active proteins HDAC1 or HDAC2, the histone chaperone retinoblastoma-associated protein 46/retinoblastoma-binding protein 7 (RBAP46/RBBP7) or RBAP48/RBBP4, the SIN3-associated protein 30 (SAP30), and the suppressor of defective silencing 3 (SDS3). Here, we overcome a bottleneck limiting the molecular characterization of the REST/NRSF-SIN3 transcriptional corepressor complex. To this end, SIN3 genes were amplified from the complementary DNA of neural stem/progenitor cells, and expressed in a baculovirus/insect cell expression system. We show that the isolates bind to DNA harboring RE1/NRSE sites and demonstrate that the histone deacetylase activity is blocked by small-molecule inhibitors. Thus, our isolates open up for future biomedical research on this critical transcriptional repressor complex and are envisioned as tool for drug testing.

Reactive Oxygen Species-Mediated Mitochondrial Dysfunction Triggers Sodium Valproate-Induced Cytotoxicity in Human Colorectal Adenocarcinoma Cells

BACKGROUND

Colorectal cancer (CRC) is one of the frequently diagnosed cancers worldwide. Currently used chemotherapeutic drugs have several side effects. Histone deacetylase (HDAC) enzyme inhibitors possess potential anti-cancer effects. Therefore, we investigated the cytotoxic potential of sodium valproate, a HDAC inhibitor in human colorectal adenocarcinoma (HT-29) cells.

METHODS

MTT assay was used to analyze the cytotoxicity of HT-29 cells. Intracellular reactive oxygen species (ROS) induction was evaluated by dichloro-dihydro-fluorescein diacetate staining. Dual staining with acridine orange/ethidium bromide was used to investigate the morphology-related apoptotic cell death. Mitochondrial membrane potential was analyzed by rhodamine 123 staining. E-cadherin protein expression was examined by immunofluorescence staining.

RESULTS

Sodium valproate at 2 and 4 mM/mL treatments significantly induced cytotoxicity. Increased intracellular ROS expression was observed in the cells treated with sodium valproate. This treatment also induced mitochondrial dissipation, apoptosis-related morphological damage, and E-cadherin expression in HT-29 cells.

CONCLUSIONS

Our present results suggest that sodium valproate is cytotoxic to HT-29 cells due to its pro-oxidative and apoptosis inducing potential. Sodium valproate can be used as an adjuvant along with standard chemotherapeutic agents in CRC patients after necessary in vivo and clinical studies.

Thirty Years of HDAC Inhibitors: 2020 Insight and Hindsight

It is now 30 years since the first report of a potent zinc-dependent histone deacetylase (HDAC) inhibitor appeared. Since then, five HDAC inhibitors have received regulatory approval for cancer chemotherapy while many others are in clinical development for oncology as well as other therapeutic indications. This Perspective reviews the biological and medicinal chemistry advances over the past 3 decades with an emphasis on the design of selective inhibitors that discriminate between the 11 human HDAC isoforms.

Histone deacetylases as targets in autoimmune and autoinflammatory diseases

Reversible lysine acetylation of histones is a key epigenetic regulatory process controlling gene expression. Reversible histone acetylation is mediated by two opposing enzyme families: histone acetyltransferases (HATs) and histone deacetylases (HDACs). Moreover, many non-histone targets of HATs and HDACs are known, suggesting a crucial role for lysine acetylation as a posttranslational modification on the cellular proteome and protein function far beyond chromatin-mediated gene regulation. The HDAC family consists of 18 members and pan-HDAC inhibitors (HDACi) are clinically used for the treatment of certain types of cancer. HDACi or individual HDAC member-deficient (cell lineage-specific) mice have also been tested in a large number of preclinical mouse models for several autoimmune and autoinflammatory diseases and in most cases HDACi treatment results in an attenuation of clinical disease severity. A reduction of disease severity has also been observed in mice lacking certain HDAC members. This indicates a high therapeutic potential of isoform-selective HDACi for immune-mediated diseases. Isoform-selective HDACi and thus targeted inactivation of HDAC isoforms might also overcome the adverse effects of current clinically approved pan-HDACi. This review provides a brief overview about the fundamental function of HDACs as epigenetic regulators, highlights the roles of HDACs beyond chromatin-mediated control of gene expression and summarizes the studies showing the impact of HDAC inhibitors and genetic deficiencies of HDAC members for the outcome of autoimmune and autoinflammatory diseases with a focus on rheumatoid arthritis, inflammatory bowel disease and experimental autoimmune encephalomyelitis (EAE) as an animal model of multiple sclerosis.

Targeting the unfolded protein response in head and neck and oral cavity cancers

Many FDA-approved anti-cancer therapies, targeted toward a wide array of molecular targets and signaling networks, have been demonstrated to activate the unfolded protein response (UPR). Despite a critical role for UPR signaling in the apoptotic execution of cancer cells by many of these compounds, the authors are currently unaware of any instance whereby a cancer drug was developed with the UPR as the intended target. With the essential role of the UPR as a driving force in the genesis and maintenance of the malignant phenotype, a great number of pre-clinical studies have surged into the medical literature describing the ability of dozens of compounds to induce UPR signaling in a myriad of cancer models. The focus of the current work is to review the literature and explore the role of the UPR as a mediator of chemotherapy-induced cell death in squamous cell carcinomas of the head and neck (HNSCC) and oral cavity (OCSCC), with an emphasis on preclinical studies.

The underlying molecular mechanism and potential drugs for treatment in papillary renal cell carcinoma: A study based on TCGA and Cmap datasets

Papillary renal cell carcinoma (PRCC) accounts for 15–20% of all kidney neoplasms and continually attracts attention due to the increase in the incidents in which it occurs. The molecular mechanism of PRCC remains unclear and the efficacy of drugs that treat PRCC lacks sufficient evidence in clinical trials. Therefore, it is necessary to investigate the underlying mechanism in the development of PRCC and identify additional potential anti-PRCC drugs for its treatment. The differently expressed genes (DEGs) of PRCC were identified, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses for functional annotation. Then, potential drugs for PRCC treatment were predicted by Connectivity Map (Cmap) based on DEGs. Furthermore, the latent function of query drugs in PRCC was explored by integrating drug-target, drug-pathway and drug-protein interactions. In total, 627 genes were screened as DEGs, and these DEGs were annotated using KEGG pathway analyses and were clearly associated with the complement and coagulation cascades, amongst others. Then, 60 candidate drugs, as predicted based on DEGs, were obtained from the Cmap database. Vorinostat was considered as the most promising drug for detailed discussion. Following protein-protein interaction (PPI) analysis and molecular docking, vorinostat was observed to interact with C3 and ANXN1 proteins, which are the upregulated hub genes and may serve as oncologic therapeutic targets in PRCC. Among the top 20 metabolic pathways, several significant pathways, such as complement and coagulation cascades and cell adhesion molecules, may greatly contribute to the development and progression of PRCC. Following the performance of the PPI network and molecular docking tests, vorinostat exhibited a considerable and promising application in PRCC treatment by targeting C3 and ANXN1.

Histone Deacetylases (HDACs) Guided Novel Therapies for T-cell lymphomas

T-cell lymphomas are a heterogeneous group of cancers with different pathogenesis and poor prognosis. Histone deacetylases (HDACs) are epigenetic modifiers that modulate many key biological processes. In recent years, HDACs have been fully investigated for their roles and potential as drug targets in T-cell lymphomas. In this review, we have deciphered the modes of action of HDACs, HDAC inhibitors as single agents, and HDACs guided combination therapies in T-cell lymphomas. The overview of HDACs on the stage of T-cell lymphomas, and HDACs guided therapies both as single agents and combination regimens endow great opportunities for the cure of T-cell lymphomas.

Compounds targeting class II histone deacetylases do not cause panHDACI-associated impairment of megakaryocyte differentiation

Histone deacetylase inhibitors (HDACIs) have demonstrated effectiveness against lymphomas and myelomas in clinical practice. However, common to all currently approved broad-acting HDACIs (panHDACIs) is dose-limiting thrombocytopenia, which has prevented wider use in cancer therapy. Using CD34⁺ hematopoietic stem cells (HSCs), we show that megakaryocyte (MK) cell maturation and differentiation are impaired by panHDACIs, correlating to clinical thrombocytopenia. Importantly, we demonstrate that inhibitors of class II histone deacetylases (HDACs), including LMK235 and tubacin at clinically relevant concentrations, do not affect MK maturation. Furthermore, we show that HDACI-induced impairment of MK differentiation is associated with reduction of protein levels of the transcription factor GATA-1, but not tubulin hyperacetylation. Finally, we report that panHDACIs trigger a rapid loss of GATA-1 protein via a proteasome-dependent pathway. Our data support the notion that specifically targeting class II HDACs in cancer treatment is a potential strategy that would offer a safer alternative than current panHDACIs.

Chronic clozapine treatment restrains via HDAC2 the performance of mGlu2 receptor agonism in a rodent model of antipsychotic activity

Preclinical findings in rodent models pointed toward activation of metabotropic glutamate 2/3 (mGlu2/3) receptors as a new pharmacological approach to treat psychosis. However, more recent studies failed to show clinical efficacy of mGlu2/3 receptor agonism in schizophrenia patients. We previously proposed that long-term antipsychotic medication restricted the therapeutic effects of these glutamatergic agents. However, little is known about the molecular mechanism underlying the potential repercussion of previous antipsychotic exposure on the therapeutic performance of mGlu2/3 receptor agonists. Here we show that this maladaptive effect of antipsychotic treatment is mediated mostly via histone deacetylase 2 (HDAC2). Chronic treatment with the antipsychotic clozapine led to a decrease in mouse frontal cortex mGlu2 mRNA, an effect that required expression of both HDAC2 and the serotonin 5-HT_2A receptor. This transcriptional alteration occurred in association with HDAC2-dependent repressive histone modifications at the mGlu2 promoter. We found that chronic clozapine treatment decreased via HDAC2 the capabilities of the mGlu2/3 receptor agonist LY379268 to activate G-proteins in the frontal cortex of mice. Chronic clozapine treatment blunted the antipsychotic-related behavioral effects of LY379268, an effect that was not observed in HDAC2 knockout mice. More importantly, co-administration of the class I and II HDAC inhibitor SAHA (vorinostat) preserved the antipsychotic profile of LY379268 and frontal cortex mGlu2/3 receptor density in wild-type mice. These findings raise concerns on the design of previous clinical studies with mGlu2/3 agonists, providing the rationale for the development of HDAC2 inhibitors as a new epigenetic-based approach to improve the currently limited response to treatment with glutamatergic antipsychotics.

TACC3 overexpression in cholangiocarcinoma correlates with poor prognosis and is a potential anti-cancer molecular drug target for HDAC inhibitors

Histone deacetylases (HDACs) have been implicated in multiple malignant tumors, and HDAC inhibitors (HDACIs) exert anti-cancer effects. However, the expression of HDACs and the anti-tumor mechanism of HDACIs in cholangiocarcinoma (CCA) have not yet been elucidated. In this study, we found that expression of HDACs 2, 3, and 8 were up-regulated in CCA tissues and those patients with high expression of HDAC2 and/or HDAC3 had a worse prognosis. In CCA cells, two HDACIs, trichostatin (TSA) and vorinostat (SAHA), suppressed proliferation and induced apoptosis and G2/M cycle arrest. Microarray analysis revealed that TACC3 mRNA was down-regulated in CCA cells treated with TSA. TACC3 was highly expressed in CCA tissues and predicted a poor prognosis in CCA patients. TACC3 knockdown induced G2/M cycle arrest and suppressed the invasion, metastasis, and proliferation of CCA cells, both in vitro and in vivo. TACC3 overexpression reversed the effects of its knockdown. These findings suggest TACC3 may be a useful prognostic biomarker for CCA and is a potential therapeutic target for HDACIs.

Epimutational profile of hematologic malignancies as attractive target for new epigenetic therapies

In recent years, recurrent somatic mutations in epigenetic regulators have been identified in patients with hematological malignancies. Furthermore, chromosomal translocations in which the fusion protein partners are themselves epigenetic regulators or where epigenetic regulators are recruited/targeted by oncogenic fusion proteins have also been described. Evidence has accumulated showing that "epigenetic drugs" are likely to provide clinical benefits in several hematological malignancies, granting their approval for the treatment of myelodysplastic syndromes and cutaneous T-cell lymphomas. A large number of pre-clinical and clinical trials evaluating epigenetic drugs alone or in combination therapies are ongoing. The aim of this review is to provide a comprehensive summary of known epigenetic alterations and of the current use of epigenetic drugs for the treatment of hematological malignancies.

HDAC3 negatively regulates spatial memory in a mouse model of Alzheimer's disease

The accumulation and deposition of beta-amyloid (Aβ) is a key neuropathological hallmark of Alzheimer's disease (AD). Histone deacetylases (HDACs) are promising therapeutic targets for the treatment of AD, while the specific HDAC isoforms associated with cognitive improvement are poorly understood. In this study, we investigate the role of HDAC3 in the pathogenesis of AD. Nuclear HDAC3 is significantly increased in the hippocampus of 6- and 9-month-old APPswe/PS1dE9 (APP/PS1) mice compared with that in age-matched wild-type C57BL/6 (B6) mice. Lentivirus -mediated inhibition or overexpression of HDAC3 was used in the hippocampus of APP/PS1 mice to investigate the role of HDAC3 in spatial memory, amyloid burden, dendritic spine density, glial activation and tau phosphorylation. Inhibition of HDAC3 in the hippocampus attenuates spatial memory deficits, as indicated in the Morris water maze test, and decreases amyloid plaque load and Aβ levels in the brains of APP/PS1 mice. Dendritic spine density is increased, while microglial activation is alleviated after HDAC3 inhibition in the hippocampus of 9-month-old APP/PS1 mice. Furthermore, HDAC3 overexpression in the hippocampus increases Aβ levels, activates microglia, and decreases dendritic spine density in 6-month-old APP/PS1 mice. In conclusion, our results indicate that HDAC3 negatively regulates spatial memory in APP/PS1 mice and HDAC3 inhibition might represent a potential therapy for the treatment of AD.

Cancer metabolism: New insights into classic characteristics

Initial studies of cancer metabolism in the early 1920s found that cancer cells were phenotypically characterized by aerobic glycolysis, in that these cells favor glucose uptake and lactate production, even in the presence of oxygen. This property, called the Warburg effect, is considered a hallmark of cancer. The mechanism by which these cells acquire aerobic glycolysis has been uncovered. Acidic extracellular fluid, secreted by cancer cells, induces a malignant phenotype, including invasion and metastasis. Cancer cells survival depends on a critical balance of redox status, which is regulated by amino acid metabolism. Glutamine is extremely important for oxidative phosphorylation and redox regulation. Cells highly dependent on glutamine and that cannot survive with glutamine are called glutamine-addicted cells. Metabolic reprogramming has been observed in cancer stem cells, which have the property of self-renewal and are resistant to chemotherapy and radiotherapy. These findings suggest that studies of cancer metabolism can reveal methods of preventing cancer recurrence and metastasis.

CG200745, an HDAC inhibitor, induces anti-tumour effects in cholangiocarcinoma cell lines via miRNAs targeting the Hippo pathway

Cholangiocarcinoma is a devastating malignancy with fatal complications that exhibits low response and resistance to chemotherapy. Here, we evaluated the anticancer effects of CG200745, a novel histone deacetylase inhibitor, either alone or in combination with standard chemotherapy drugs in cholangiocarcinoma cells. CG200745 dose-dependently reduced the viability of cholangiocarcinoma cells in vitro and decreased tumour volume and weight in a xenograft model. Administering CG200745 along with other chemotherapeutic agents including gemcitabine, 5-fluorouracil (5-FU), cisplatin, oxaliplatin, or gemcitabine plus cisplatin further decreased cholangiocarcinoma cell viability, with a combination index < 1 that indicated synergistic action. CG200745 also enhanced the sensitivity of gemcitabine-resistant cells to gemcitabine and 5-FU, thereby decreasing cell viability and inducing apoptosis. This was accompanied by downregulation of YAP, TEAD4, TGF-β2, SMAD3, NOTCH3, HES5, Axl, and Gas6 and upregulation of the miRNAs miR-22-3p, miR-22-5p, miR-194-5p, miR-194-3p, miR-194-5p, miR-210-3p, and miR-509-3p. The Ingenuity Pathway Analysis revealed that CG200745 mainly targets the Hippo signalling pathway by inducing miR-509-3p expression. Thus, CG200745 inhibits cholangiocarcinoma growth in vitro and in vivo, and acts synergistically when administered in combination with standard chemotherapeutic agents, enabling dose reduction. CG200745 is therefore expected to improve the outcome of cholangiocarcinoma patients who exhibit resistance to conventional therapies.

Histone deacetylases (HDACs) as therapeutic target for depressive disorders

Major depressive disorder (MDD) represents approximately 40% of the disability caused by mental illnesses globally. The poorly understood pathophysiology and limited efficiency of pharmacological treatment (based primarily on the principles of the monoaminergic hypothesis) make depression a serious medical, public and socio-economical problem. An increasing number of studies suggest that epigenetic modifications (alterations in gene expression that are not due to changes in DNA sequence) in certain brain regions and neural circuits represent a key mechanism through which environmental factors interact with individual's genetic constitution to affect risk of mental disorders. Accordingly, chromatin-based epigenetic regulation seems to be a promising direction for the development of new, more effective antidepressant drugs. Recently, several inhibitors of histone deacetylases (HDAC) have been extensively studied in the context of antidepressant action. So far, none of them has been used to treat depression in humans due to the low selectivity for specific HDAC isoforms, and consequently, a risk of serious adverse events. In this review, we focus on the HDAC inhibitors (HDACi) with the greatest antidepressant efficacy and their activity in the preclinical studies. Moreover, we discuss their potential therapeutic usefulness in depression and the main limitations.

Inflammatory cytokines down-regulate the barrier-protective prostasin-matriptase proteolytic cascade early in experimental colitis

Compromised gastrointestinal barrier function is strongly associated with the progressive and destructive pathologies of the two main forms of irritable bowel disease (IBD), ulcerative colitis (UC), and Crohn's disease (CD). Matriptase is a membrane-anchored serine protease encoded by suppression of tumorigenicity-14 (ST14) gene, which is critical for epithelial barrier development and homeostasis. Matriptase barrier-protective activity is linked with the glycosylphosphatidylinositol (GPI)-anchored serine protease prostasin, which is a co-factor for matriptase zymogen activation. Here we show that mRNA and protein expression of both matriptase and prostasin are rapidly down-regulated in the initiating inflammatory phases of dextran sulfate sodium (DSS)-induced experimental colitis in mice, and, significantly, the loss of these proteases precedes the appearance of clinical symptoms, suggesting their loss may contribute to disease susceptibility. We used heterozygous St14 hypomorphic mice expressing a promoter-linked β-gal reporter to show that inflammatory colitis suppresses the activity of the St14 gene promoter. Studies in colonic T84 cell monolayers revealed that barrier disruption by the colitis-associated Th2-type cytokines, IL-4 and IL-13, down-regulates matriptase as well as prostasin through phosphorylation of the transcriptional regulator STAT6 and that inhibition of STAT6 with suberoylanilide hydroxamic acid (SAHA) restores protease expression and reverses cytokine-induced barrier dysfunction. Both matriptase and prostasin are significantly down-regulated in colonic tissues from human subjects with active ulcerative colitis or Crohn's disease, implicating the loss of this barrier-protective protease pathway in the pathogenesis of irritable bowel disease.

Why cure, why now?

Combination antiretroviral therapy (cART) is highly effective at preventing morbidity and mortality due to infection with human immunodeficiency virus (HIV), but does not eradicate the virus. Consequently, cART must be administered life-long. Recent progress has stimulated research towards a cure of HIV infection. Approaches under investigation include hematopoietic stem cell transplantation, latency reactivating agents, immune based therapies, and cell-based therapies. Each of these approaches carries potential risks that must be weighed against the availability of safe and effective cART. Balancing the risks and benefits of this research poses unique challenges to potential study participants, clinicians and investigators.

Epigenetics of oropharyngeal squamous cell carcinoma: opportunities for novel chemotherapeutic targets

Epigenetic modifications are heritable changes in gene expression that do not directly alter DNA sequence. These modifications include DNA methylation, histone post-translational modifications, small and non-coding RNAs. Alterations in epigenetic profiles cause deregulation of fundamental gene expression pathways associated with carcinogenesis. The role of epigenetics in oropharyngeal squamous cell carcinoma (OPSCC) has recently been recognized, with implications for novel biomarkers, molecular diagnostics and chemotherapeutics. In this review, important epigenetic pathways in human papillomavirus (HPV) positive and negative OPSCC are summarized, as well as the potential clinical utility of this knowledge.This material has never been published and is not currently under evaluation in any other peer-reviewed publication.

Action mechanisms of histone deacetylase inhibitors in the treatment of hematological malignancies

Histone deacetylases (HDACs) critically regulate gene expression by determining the acetylation status of histones. Studies have increasingly focused on the activities of HDACs, especially involving non-histone proteins, and their various biological effects. Aberrant HDAC expression observed in several kinds of human tumors makes HDACs potential targets for cancer treatment. Several preclinical studies have suggested that HDAC inhibitors show some efficacy in the treatment of acute myelogenous leukemia with AML1-ETO, which mediates transcriptional repression through its interaction with a complex including HDAC1. Recurrent mutations in epigenetic regulators are found in T-cell lymphomas (TCLs), and HDAC inhibitors and hypomethylating agents were shown to act cooperatively in the treatment of TCLs. Preclinical modeling has suggested that persistent activation of the signal transducer and activator of transcription signaling pathway could serve as a useful biomarker of resistance to HDAC inhibitor in patients with cutaneous TCL. Panobinostat, a pan-HDAC inhibitor, in combination with bortezomib and dexamethasone, has achieved longer progression-free survival in patients with relapsed/refractory multiple myeloma (MM) than the placebo in combination with bortezomib and dexamethasone. Panobinostat inhibited MM cell growth by degrading protein phosphatase 3 catalytic subunit α (PPP3CA), a catalytic subunit of calcineurin. This degradation was suggested to be mediated by the blockade of the chaperone function of heat shock protein 90 due to HDAC6 inhibition. Aberrant PPP3CA expression in advanced MM indicated a possible correlation between high PPP3CA expression and the pathogenesis of MM. Furthermore, PPP3CA was suggested as a common target of panobinostat and bortezomib.