Histone acetylases and deacetylases in cell proliferation

Heterocycles-Containing HDAC Inhibitors Active in Cancer: An Overview of the Last Fifteen Years

Cancer is one of the primary causes of mortality worldwide. Despite nowadays are numerous therapeutic treatments to fight tumor progression, it is still challenging to completely overcome it. It is known that Histone Deacetylases (HDACs), epigenetic enzymes that remove acetyl groups from lysines on histone's tails, are overexpressed in various types of cancer, and their inhibition represents a valid therapeutic strategy. To date, some HDAC inhibitors have achieved FDA approval. Nevertheless, several other potential drug candidates have been developed. This review aims primarily to be comprehensive of the studies done so far regarding HDAC inhibitors bearing heterocyclic rings since their therapeutic potential is well known and has gained increasing interest in recent years. Hence, inserting heterocyclic moieties in the HDAC-inhibiting scaffold can be a valuable strategy to provide potent and/or selective compounds. Here, in addition to summarizing the properties of novel heterocyclic HDAC inhibiting compounds, we also provide ideas for developing new, more potent, and selective compounds for treating cancer.

Amino acid metabolism in tumor biology and therapy

Amino acid metabolism plays important roles in tumor biology and tumor therapy. Accumulating evidence has shown that amino acids contribute to tumorigenesis and tumor immunity by acting as nutrients, signaling molecules, and could also regulate gene transcription and epigenetic modification. Therefore, targeting amino acid metabolism will provide new ideas for tumor treatment and become an important therapeutic approach after surgery, radiotherapy, and chemotherapy. In this review, we systematically summarize the recent progress of amino acid metabolism in malignancy and their interaction with signal pathways as well as their effect on tumor microenvironment and epigenetic modification. Collectively, we also highlight the potential therapeutic application and future expectation.

Potential therapies targeting nuclear metabolic regulation in cancer

The interplay between genetic alterations and metabolic dysregulation is increasingly recognized as a pivotal axis in cancer pathogenesis. Both elements are mutually reinforcing, thereby expediting the ontogeny and progression of malignant neoplasms. Intriguingly, recent findings have highlighted the translocation of metabolites and metabolic enzymes from the cytoplasm into the nuclear compartment, where they appear to be intimately associated with tumor cell proliferation. Despite these advancements, significant gaps persist in our understanding of their specific roles within the nuclear milieu, their modulatory effects on gene transcription and cellular proliferation, and the intricacies of their coordination with the genomic landscape. In this comprehensive review, we endeavor to elucidate the regulatory landscape of metabolic signaling within the nuclear domain, namely nuclear metabolic signaling involving metabolites and metabolic enzymes. We explore the roles and molecular mechanisms through which metabolic flux and enzymatic activity impact critical nuclear processes, including epigenetic modulation, DNA damage repair, and gene expression regulation. In conclusion, we underscore the paramount significance of nuclear metabolic signaling in cancer biology and enumerate potential therapeutic targets, associated pharmacological interventions, and implications for clinical applications. Importantly, these emergent findings not only augment our conceptual understanding of tumoral metabolism but also herald the potential for innovative therapeutic paradigms targeting the metabolism-genome transcriptional axis.

DNA methylation and lipid metabolism are involved in GA-induced maize aleurone layers PCD as revealed by transcriptome analysis

BACKGROUND

The aleurone layer is a part of many plant seeds, and during seed germination, aleurone cells undergo PCD, which is promoted by GA from the embryo. However, the numerous components of the GA signaling pathway that mediate PCD of the aleurone layers remain to be identified. Few genes and transcriptomes have been studied thus far in aleurone layers to improve our understanding of how PCD occurs and how the regulatory mechanism functions during PCD. Our previous studies have shown that histone deacetylases (HDACs) are required in GA-induced PCD of aleurone layer. To further explore the molecular mechanisms by which epigenetic modifications regulate aleurone PCD, we performed a global comparative transcriptome analysis of embryoless aleurones treated with GA or histone acetylase (HAT) inhibitors.

RESULTS

In this study, a total of 7,919 differentially expressed genes (DEGs) were analyzed, 2,554 DEGs of which were found to be common under two treatments. These identified DEGs were involved in various biological processes, including DNA methylation, lipid metabolism and ROS signaling. Further investigations revealed that inhibition of DNA methyltransferases prevented aleurone PCD, suggesting that active DNA methylation plays a role in regulating aleurone PCD. GA or HAT inhibitor induced lipoxygenase gene expression, leading to lipid degradation, but this process was not affected by DNA methylation. However, DNA methylation inhibitor could regulate ROS-related gene expression and inhibit GA-induced production of hydrogen peroxide (H2O2).

CONCLUSION

Overall, linking of lipoxygenase, DNA methylation, and H2O2 may indicate that GA-induced higher HDAC activity in aleurones causes breakdown of lipids via regulating lipoxygenase gene expression, and increased DNA methylation positively mediates H2O2 production; thus, DNA methylation and lipid metabolism pathways may represent an important and complex signaling network in maize aleurone PCD.

Exploring new histone deacetylase 6 inhibitors and their effects on reversing the α-tubulin deacetylation and cell morphology changes caused by methamphetamine

Indazole-based HDAC6 inhibitors with novel zinc-binding modifications were synthesized and evaluated to determine their potential to inhibit HDAC6. The analogs were subjected to a histone deacetylase (HDAC) enzyme assay, which led to identification of compounds 3a and 3b. Both compounds demonstrated higher potency and selectivity as HDAC6 inhibitors with IC50 values of 9.1 nM and 9.0 nM, respectively, and highlighted the importance of the hydroxamic acid moiety for binding to Zn2+ inside the catalytic pocket of HDAC enzymes. In the neuroblastoma SH-SY5Y cell line, both compounds efficiently acetylated α-tubulin but not histone H3 at a low concentration of 0.5 µM. Moreover, compounds 3a and 3b effectively reversed the deacetylation of α-tubulin caused by methamphetamine in the SH-SY5Y cell line, suggesting the potential usefulness of HDAC6 selective inhibition in restoring blood brain barrier integrity by reversing methamphetamine-induced deacetylation.

P300 increases CSNK2A1 expression which accelerates colorectal cancer progression through activation of the PI3K-AKT-mTOR axis

Casein kinase 2 alpha 1 (CSNK2A1) is a known oncogene, but its role in the progression of colorectal cancer (CRC) remain undefined. Here, we investigated the effects of CSNK2A1 during CRC development. In the current study, CSNK2A1 expression in the colorectal cancer cell lines (HCT116, SW480, HT29, SW620 and Lovo) vs. normal colorectal cell line (CCD841 CoN) were compared via RT-qPCR and western blotting. The role of CSNK2A1 on CRC growth and metastases were investigated through Transwell assay. Immunofluorescence analysis was used to investigate the expression of EMT-related proteins. The association between P300/H3K27ac and CSNK2A1 were analyzed using UCSC bioinformatics and Chromatin-immunoprecipitation (Ch-IP) assays. Results revealed that both the mRNA and protein levels of CSNK2A1 in HCT116, SW480, HT29, SW620 and Lovo cells were upregulated. Additionally, P300-mediated H3K27ac activation at the CSNK2A1 promoter was found to drive the increase in CSNK2A1 expression. Transwell assay showed that CSNK2A1 overexpression increased the migration and invasion of HCT116 and SW480 cells, which decreased following CSNK2A1 silencing. CSNK2A1 was also found to facilitate EMT in HCT116 cells, evidenced by the increases of N-cadherin, Snail and Vimentin expression, and loss of E-cadherin. Importantly, the levels of p-AKT-S473/AKT, p-AKT-T308/AKT, and p-mTOR/mTOR in cells overexpressing CSNK2A1 were high, but significantly decreased following CSNK2A silencing. The PI3K inhibitor BAY-806946 could reverse the increase in p-AKT-S473/AKT, p-AKT-T308/AKT, p-mTOR/mTOR induced by CSNK2A1 overexpression and suppress CRC cell migration and invasion. In conclusion, we report a positive feedback mechanism through which P300 enhances CSNK2A1 expression and accelerates CRC progression through the activation of the PI3K-AKT-mTOR axis.

Clear cell sarcoma: state-of-the art and perspectives

INTRODUCTION

Clear cell sarcoma (CCS) is an ultrarare soft tissue sarcoma (STS) with a poor prognosis due to its propensity to metastasize and its low chemosensitivity. The standard treatment of localized CCS consists of wide surgical excision with or without additive radiotherapy. However, unresectable CCS is generally treated with conventional systemic therapies available for treatment of STS despite the weak scientific evidence to support its use.

AREAS COVERED

In this review, we discuss the clinicopathologic characteristics of CSS, as well as the current treatment landscape and future therapeutic approaches.

EXPERT OPINION

The current treatment strategy of advanced CCSs, based on STSs regimens, shows a lack of effective options. Combination therapiesin particular, the association of immunotherapy and TKIs, represent a promising approach. Translational studies are needed in order to decipher the regulatory mechanisms involved in the oncogenesis of this ultrarare sarcoma and identify potential molecular targets.

Cloning and Expression Analysis of HAT1 and HDAC1 in the Testes of Mature Yaks and Their Sterile Hybrids

Simple Summary

Cattle-yak is the hybrid between male cattle (Bos taurus) and female yak (Bos grunniens). Male cattle-yak can not produce normal sperm. The mechanisms that underlie cattle-yak male sterility have not been elucidated. Histone acetylation is a common regulation mode that plays an important role in the development of gametes. The objective of this study was to explore the molecular mechanism of male sterility in yak hybrids based on histone acetyltransferase 1 (HAT1) and histone deacetylase 1 (HDAC1), two enzymes that regulate histone acetylation. The mRNA and protein expression levels of HAT1 in the testes of adult cattle-yaks were significantly lower than in adult yaks, and the protein expression levels of HDAC1 were significantly higher than in yaks. In addition, H3K9 acetylation levels in cattle-yak testes were significantly lower than in yaks. These results suggest that male sterility in cattle-yaks might be associated with decreased histone acetylation levels in the testes.

Abstract

The objective of this study was to explore the molecular mechanism of male sterility in yak hybrids based on HAT1 and HDAC1. Total RNA was extracted from the testes of adult yaks (n = 11) and sterile cattle-yaks (n = 11) followed by reverse transcription. The coding sequence (CDS) of yak HAT1 and HDAC1 were obtained by conventional polymerase chain reaction (PCR) and gene cloning. The testicular mRNA and protein levels of HAT1 and HDAC1 in yaks and cattle-yaks were detected by quantitative PCR (qPCR) and Western blotting, respectively, and the histone H3 lysine 9 (H3K9) histone acetylation level in the testes of yaks and cattle-yaks was assayed using enzyme linked immunosorbent assay (ELISA). The results showed that the CDS of HAT1 and HDAC1 were 1242 bp and 1449 bp in length, encoding 413 and 482 amino acids, respectively; yaks had a similar mRNA sequence as cattle in both genes. The testicular mRNA and protein levels of HAT1 of cattle-yaks were significantly lower than those of yaks, and the protein level of HDAC1 was significantly higher than that of yaks. ELISA showed that the acetylation level of testicular H3K9 was significantly lower in yak hybrids than that of yaks. The present results suggest that the decreased level of HAT1 and increased level of HDAC1 may result in the decreased H3K9 acetylation in cattle-yaks and might be associated with their sterility.

Protective Effects of Diets Rich in Polyphenols in Cigarette Smoke (CS)-Induced Oxidative Damages and Associated Health Implications

Cigarette smoking has been responsible for causing many life-threatening diseases such as pulmonary and cardiovascular diseases as well as lung cancer. One of the prominent health implications of cigarette smoking is the oxidative damage of cellular constituents, including proteins, lipids, and DNA. The oxidative damage is caused by reactive oxygen species (ROS, oxidants) present in the aqueous extract of cigarette smoke (CS). In recent years, there has been considerable interest in the potential health benefits of dietary polyphenols as natural antioxidant molecules. Epidemiological studies strongly suggest that long-term consumption of diets (fruits, vegetables, tea, and coffee) rich in polyphenols offer protective effects against the development of cancer, cardiovascular diseases, diabetes, osteoporosis, and neurodegenerative diseases. For instance, green tea has chemopreventive effects against CI-induced lung cancer. Tea might prevent CS-induced oxidative damages in diseases because tea polyphenols, such as catechin, EGCG, etc., have strong antioxidant properties. Moreover, apple polyphenols, including catechin and quercetin, provide protection against CS-induced acute lung injury such as chronic obstructive pulmonary disease (COPD). In CS-induced health problems, the antioxidant action is often accompanied by the anti-inflammatory effect of polyphenols. In this narrative review, the CS-induced oxidative damages and the associated health implications/pathological conditions (or diseases) and the role of diets rich in polyphenols and/or dietary polyphenolic compounds against various serious/chronic conditions of human health have been delineated.

H2A.Z acetylation by lincZNF337-AS1 via KAT5 implicated in the transcriptional misregulation in cancer signaling pathway in hepatocellular carcinoma

In eukaryotes, histones and their variants are essential for chromatin structure and function; both play important roles in the regulation of gene transcription, as well as the development of tumors. We aimed to explore the genomics data of hepatocellular carcinoma (HCC), combined with literature analysis, in terms of the histone variant H2A.Z. Cell phenotype assay confirmed the effect of H2A.Z on the proliferation, metastasis, apoptosis, and cell cycle of HCC cells. H2A.Z was shown to function via the tumor dysregulation signaling pathway, with BCL6 as its interacting protein. In addition, the acetylation level of H2A.Z was higher in HCC and was related to tumor formation. We found the acetylation of H2A.Z to be related to and regulated by lincZNF337-AS1. LincZNF337-AS1 was found to bind to H2A.Z and KAT5 at different sites, promoting the acetylation of H2A.Z through KAT5. We concluded that, in HCC, H2A.Z is an oncogene, whose acetylation promotes the transcription of downstream genes, and is regulated by lincZNF331-AS1.

Epidrug Modulated Expression of MiR--152 and MiR-148a Reverse Cisplatin Resistance in Ovarian Cancer Cells: An Experimental In-vitro Study

Cisplatin is a common agent which is used to treat Epithelial Ovarian Cancer (EOC), but cisplatin resistance is a major obstacle in successful treatment of ovarian cancer. Aberration in epigenetic changes play an important role in disregulation of gene expression. MiR-152 and miR-148a are frequently down-regulated in EOC due to promoter hyper-methylation. DNA methyltransferase1 (DNMT1), the main enzyme in maintenance of the pattern of DNA methylation, is one of the targets of miR-152 and miR-148a. Aberrantly up-regulation of DNMT1 is responsible for silencing of tumor suppressor genes in carcinogenesis. We hypothesized that re-expression of miR-152 and miR-148a and consequently down-regulation of DNMT1 may resensitize cancerous cells to chemotherapeutics agents. The aim of the present study is to investigate the effect of 5-azacytidine (5-Aza) and Trichostatin A on miR-152 and miR-148a expression in A2780CP ovarian cancer cell line. Optimal doses of 5-Azacitidine and TSA were measured by 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. A2780CP cell line was treated by each drugs, alone or in combination and the expression of miR-148a, miR-152 and DNMT1 was evaluated by Real-Time Quantitative Reverse Transcription-Polymerase Chain Reaction (RT-qPCR). The results revealed that TSA and 5-Azacytidine are able to revive the expression of miR-148a and miR-152 genes and mediate growth inhibition of epithelial ovarian cancer cells. The present study suggests that re-expression of miR-148a and miR-152 by epigenetic therapy aiming to DNMT1 suppression might resensitize resistant ovarian tumors to conventional chemotherapy.

Tailored Quinolines Demonstrate Flexibility to Exert Antitumor Effects through Varied Mechanisms-A Medicinal Perspective

BACKGROUND

Quinoline is considered to be a privileged heterocyclic ring owing to its presence in diverse scaffolds endowed with promising activity profiles. In particular, quinoline containing compounds have exhibited substantial antiproliferative effects through the diverse mechanism of actions, which indicates that the heteroaryl unit is flexible as well as accessible to subtle structural changes that enable its inclusion in chemically distinct anti-tumor constructs.

METHODS

Herein, we describe a medicinal chemistry perspective on quinolines as anticancer agents by digging into the peer-reviewed literature as well as patents published in the past few years.

RESULTS

This review will serve as a guiding tool for medicinal chemists and chemical biologists to gain insights about the benefits of quinoline ring installation to tune the chemical architectures for inducing potent anticancer effects.

CONCLUSION

Quinoline ring containing anticancer agents presents enough optimism and promise in the field of drug discovery to motivate the researchers towards the continued explorations on such scaffolds. It is highly likely that adequate efforts in this direction might yield some potential cancer therapeutics in the future.

GDF-15: Diagnostic, prognostic, and therapeutic significance in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the commonest primary malignant brain tumor and has a remarkably weak prognosis. According to the aggressive form of GBM, understanding the accurate molecular mechanism associated with GBM pathogenesis is essential. Growth differentiation factor 15 (GDF-15) belongs to transforming growth factor-β superfamily with important roles to control biological processes. It affects cancer growth and progression, drug resistance, and metastasis. It also can promote stemness in many cancers, and also can stress reactions control, bone generation, hematopoietic growth, adipose tissue performance, and body growth, and contributes to cardiovascular disorders. The role GDF-15 to develop and progress cancer is complicated and remains unclear. GDF-15 possesses tumor suppressor properties, as well as an oncogenic effect. GDF-15 antitumorigenic and protumorigenic impacts on tumor development are linked to the cancer type and stage. However, the GDF-15 signaling and mechanism have not yet been completely identified because of no recognized cognate receptor.

CAP rigidification of MS-275 and chidamide leads to enhanced antiproliferative effects mediated through HDAC1, 2 and tubulin polymerization inhibition

The study focuses on the prudent design and synthesis of anilide type class I HDAC inhibitors employing a functionalized pyrrolo[2,3-d]pyrimidine skeleton as the surface recognition part. Utilization of the bicyclic aromatic ring to fabricate the target compounds was envisioned to confer rigidity to the chemical architecture of MS-275 and chidamide. In-vitro enzymatic and cellular assays led to the identification of compound 7 as a potent inhibitor of HDAC1 and 2 isoform that exerted substantial cell growth inhibitory effects against human breast MDA-MB-231, cervical HeLa, breast MDA-MB-468, colorectal DLD1, and colorectal HCT116 cell lines with an IC₅₀ values of 0.05-0.47 μM, better than MS-275 and chidamide. In addition, the anilide 7 was also endowed with a superior antiproliferative profile than MS275 and chidamide towards the human cutaneous T cell lymphoma (HH and HuT78), leukemia (HL60 and KG-1), and HDACi sensitive/resistant gastric cell lines (YCC11 and YCC3/7). Exhaustive exploration of the construct 7 confirmed it to be a microtubule-targeting agent that could trigger the cell-cycle arrest in mitosis. In pursuit of extracting the benefits of evidenced microtubule-destabilizing activity of the anilide 7, it was further evaluated against non-small-cell lung cancer cell lines as well as the multiple-drug resistant uterine cancer cell line (MES-SA/Dx5) and overwhelmingly positive results in context of inhibitory effects were attained. Furthermore, molecular modelling studies were performed and some key interactions of the anilide 7 with the amino acid residues of the active site of HDAC1 isoform and tubulin were figured out.

Expression of Adenoviral E1A in Transformed Cells as an Additional Factor of HDACi-Dependent FoxO Regulation

The adenoviral early region 1A (E1A) protein has proapoptotic and angiogenic activity, along with its chemosensitizing effect, making it the focus of increased interest in the context of cancer therapy. It was previously shown that E1A-induced chemosensitization to different drugs, including histone deacetylases inhibitors (HDACi), appears to be mediated by Forkhead box O (FoxO) transcription factors. In this study, we explore the relationship between E1A expression and the modulation of FoxO activity with HDACi sodium butyrate (NaBut). We show here that the basal FoxO level is elevated in E1A-expressing cells. Prolonged NaBut treatment leads to the inhibition of the FoxO expression and activity in E1A-expressing cells. However, in E1A-negative cells, NaBut promotes the transactivation ability of FoxO over time. A more detailed investigation revealed that the NaBut-induced decrease of FoxO activity in E1A-expressing cells is due to the NaBut-dependent decrease in E1A expression. Therefore, NaBut-induced inhibition of FoxO in E1A-positive cells can be overcome under unregulated overexpression of E1A. Remarkably, the CBP/p300-binding domain of E1Aad5 is responsible for stabilization of the FoxO protein. Collectively, these data show that the expression of E1A increases the FoxO stability but makes the FoxO level more sensitive to HDACi treatment.

Human p21-activated kinase 5 (PAK5) expression and potential mechanisms in relevant cancers: Basic and clinical perspectives for molecular cancer therapeutics

An oncogenic role, p21-activated kinase 5 (PAK5), has proven as a significant mediator for many cellular progression, which is expressed highly in human organs such as lung, liver, kidney, blood vessels endothelial cells and inflammatory cells. PAK5 was primitively detected in the cerebrum and accelerated the filopodia formation in neurocytes. It can reverse the effect of Rho and adjust its activity to mediate maintenance and development of nerve axon by binding with Cdc42-GTP. Moreover, PAK5 has been suggested to mediate protean, multitudinous and inscrutable functions in cancer. Currently, many researches indicated that PAK5 was dysregulated in ovarian cancer, cervical cancer, melanoma, osteosarcoma, renal carcinoma, breast cancer, gastric cancer and so on, which was involved in cell proliferation, apoptosis, migration and invasion. This review focuses the latest knowledge on the structure, expression, signalling pathway of PAK5, emphasizing its function in cancer.

Design, synthesis and evaluation of belinostat analogs as histone deacetylase inhibitors

Aim: Histone deacetylase (HDAC) is an attractive target for antitumor therapy. Therefore, the development of novel HDAC inhibitors is warranted. Materials & methods: A series of HDAC inhibitors based on N-hydroxycinnamamide fragment was designed as the clinically used belinostat analog using amide as the connecting unit. All target compounds were evaluated for their in vitro HDAC inhibitory activities and some selected compounds were tested for their antiproliferative activities. Conclusion: Among them, compound 7e showed an IC₅₀ value of 11.5 nM in inhibiting the HDAC in a pan-HDAC assay, being the most active compound of the series.

Hypermethylation of DcR1, DcR2, DR4, DR5 gene promoters and clinical significance in tongue carcinoma

OBJECTIVE

Tongue squamous cell carcinoma (TSCC) is one of the most common malignancies in the oral cavity, and its incidence and mortality have been constantly increasing these years. A large number of tumor suppressor genes are involved in the development of the TSCC and it has been reported that the aberrant hypermethylation of tumor suppressor genes may play a key role in the process of the TSCC. In this study, we sought to analyze the association of methylation of DcR1, DcR2, DR4 and DR5 gene promoters and clinical significance in the TSCC to evaluate association between methylation of DcR1, DcR2, DR4 and DR5 gene and Clinical Significance in tongue squamous cell carcinoma.

METHODS

Methylation-specific PCR(MSP) was used to analyze the methylation of the promoters of TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) receptors in 45 TSCC cases. Real-Time PCR was used to detect the expression of the DcR1, DcR2, DR4 and DR5 gene.

RESULTS

All the four genes (DcR1, DcR2, DR4 and DR5) showed different methylation of promoters in TSCC, while methylation of these promoters in paired adjacent normal tissues were almost undetectable. Patients with high methylation index were diagnosed at younger age when compared with the ones with low methylation index. DcR1 and DR4 hypermethylation was correlated significantly with patients' TNM stage.

CONCLUSIONS

Methylation of DcR1, DcR2,DR4 and DR5 promoters are found in TSCC and may associate with its occurrence and development. Taking the reversibility of methylation into account，methylation is a potential targeted therapy of TSCC.

Histone Deacetylase Inhibitors in Tumor Immunotherapy

BACKGROUND

With an increasing understanding of the antitumor immune response, considerable progress has been made in the field of tumor immunotherapy in the last decade. Inhibition of histone deacetylases represents a new strategy in tumor therapy and histone deacetylase inhibitors have been recently developed and validated as potential antitumor drugs. In addition to the direct antitumor effects, histone deacetylase inhibitors have been found to have the ability to improve tumor recognition by immune cells that may contribute to their antitumor activity. These immunomodolutory effects are desirable, and their in-depth comprehension will facilitate the design of novel regimens with improved clinical efficacy.

OBJECTIVE

Our goal here is to review recent developments in the application of histone deacetylase inhibitors as immune modulators in cancer treatment.

METHODS

Systemic compilation of the relevant literature in this field.

RESULTS & CONCLUSION

In this review, we summarize recent advances in the understanding of how histone deacetylase inhibitors alter immune process and discuss their effects on various cytokines. We also discuss the challenges to optimize the use of these inhibitors as immune modulators in cancer treatment. Information gained from this review will be valuable to this field and may be helpful for designing tumor immunotherapy trials involving histone deacetylase inhibitors.

H3K18ac Primes Mesendodermal Differentiation upon Nodal Signaling

Cellular responses to transforming growth factor β (TGF-β) depend on cell context. Here, we explored how TGF-β/nodal signaling crosstalks with the epigenome to promote mesendodermal differentiation. We find that expression of a group of mesendodermal genes depends on both TRIM33 and nodal signaling in embryoid bodies (EBs) but not in embryonic stem cells (ESCs). Only in EBs, TRIM33 binds these genes in the presence of expanded H3K18ac marks. Furthermore, the H3K18ac landscape at mesendodermal genes promotes TRIM33 recruitment. We reveal that HDAC1 binds to active gene promoters and interferes with TRIM33 recruitment to mesendodermal gene promoters. However, the TRIM33-interacting protein p300 deposits H3K18ac and further enhances TRIM33 recruitment. ATAC-seq data demonstrate that TRIM33 primes mesendodermal genes for activation by maintaining chromatin accessibility at their regulatory regions. Altogether, our study suggests that HDAC1 and p300 are key factors linking the epigenome through TRIM33 to the cell context-dependent nodal response during mesendodermal differentiation.

A Mechanistic and Pathophysiological Approach for Stroke Associated with Drugs of Abuse

Drugs of abuse are associated with stroke, especially in young individuals. The major classes of drugs linked to stroke are cocaine, amphetamines, heroin, morphine, cannabis, and new synthetic cannabinoids, along with androgenic anabolic steroids (AASs). Both ischemic and hemorrhagic stroke have been reported due to drug abuse. Several common mechanisms have been identified, such as arrhythmias and cardioembolism, hypoxia, vascular toxicity, vascular spasm and effects on the thrombotic mechanism, as causes for ischemic stroke. For hemorrhagic stroke, acute hypertension, aneurysm formation/rupture and angiitis-like changes have been implicated. In AAS abuse, the effect of blood pressure is rather substance specific, whereas increased erythropoiesis usually leads to thromboembolism. Transient vasospasm, caused by synthetic cannabinoids, could lead to ischemic stroke. Opiates often cause infective endocarditis, resulting in ischemic stroke and hypereosinophilia accompanied by pyogenic arthritis, provoking hemorrhagic stroke. Genetic variants are linked to increased risk for stroke in cocaine abuse. The fact that case reports on cannabis-induced stroke usually refer to the young population is very alarming.

In Silico Identification of Potential Inhibitor Against a Fungal Histone Deacetylase, RPD3 from Magnaporthe Oryzae

Histone acetylation and deacetylation play an essential role in the epigenetic regulation of gene expression. Histone deacetylases (HDAC) are a group of zinc-binding metalloenzymes that catalyze the removal of acetyl moieties from lysine residues from histone tails. These enzymes are well known for their wide spread biological effects in eukaryotes. In rice blast fungus, Magnaporthe oryzae, MoRPD3 (an ortholog of Saccharomyces cerevisiae Rpd3) was shown to be required for growth and development. Thus in this study, the class I HDAC, MoRpd3 is considered as a potential drug target, and its 3D structure was modelled and validated. Based on the model, a total of 1880 compounds were virtually screened (molecular docking) against MoRpd3 and the activities of the compounds were assessed by docking scores. The in silico screening suggested that [2-[[4-(2-methoxyethyl) phenoxy] methyl] phenyl] boronic acid (−8.7 kcal/mol) and [4-[[4-(2-methoxyethyl) phenoxy] methyl] phenyl] boronic acid (−8.5 kcal/mol) are effective in comparison to trichostatin A (−7.9 kcal/mol), a well-known general HDAC inhibitor. The in vitro studies for inhibition of appressorium formation by [2-[[4-(2-methoxyethyl) phenoxy] methyl] phenyl] boronic acid has resulted in the maximum inhibition at lower concentrations (1 μM), while the trichostatin A exhibited similar levels of inhibition at 1.5 μM. These findings thus suggest that 3D quantitative structure activity relationship studies on [2-[[4-(2-methoxyethyl) phenoxy] methyl] phenyl] boronic acid compound can further guide the design of more potential and specific HDAC inhibitors.

Structure-Based Drug Designing Recommends HDAC6 Inhibitors To Attenuate Microtubule-Associated Tau-Pathogenesis

Protein acetylation and deacetylation play vital roles in the structural and physiological behavior of target proteins. Histone deacetylase 6 (HDAC6) remains a key therapeutic target in several chronic diseases such as cancer, neurodegenerative, and hematological diseases. In tau-pathogenesis, HDAC6 tightly regulates microtubule-associated tau physiology, and its inhibition suppresses Alzheimer's phenotype. To this end, the current study has identified novel HDAC6 inhibitors by structure-based drug designing method. A pharmacophore was generated from HDAC6 in complex with trichostatin A. The selected pharmacophore had five features including two hydrogen bond donors, one hydrogen bond acceptor, and two hydrophobic features. Pharmacophore validation obtained the highest GH score of 0.80. By applying Lipinski's rule of five and ADMET Descriptors, a drug-like database of 29 183 molecules was generated from the Zinc Natural Product Database. The validated pharmacophore screened 841 drug-like molecules and was subsequently subjected to molecular docking in the active site of HDAC6. Molecular docking identified 11 hits, where they showed the highest ChemPLP score (>90.00), stable conformation, and hydrogen-bond interactions with catalytic residues of HDAC6. Finally, molecular dynamics simulation identified three molecules as potent HDAC6 inhibitors with stable root-mean-square deviation and the highest number of hydrogen bonds with the catalytic residues of HDAC6. Overall, we recommend three novel inhibitors of HDAC6, capable of suppressing the microtubule-associated tau-pathogenesis.

Computational QSAR model combined molecular descriptors and fingerprints to predict HDAC1 inhibitors

The dynamic balance between acetylation and deacetylation of histones plays a crucial role in the epigenetic regulation of gene expression. It is equilibrated by two families of enzymes: histone acetyltransferases and histone deacetylases (HDACs). HDACs repress transcription by regulating the conformation of the higher-order chromatin structure. HDAC inhibitors have recently become a class of chemical agents for potential treatment of the abnormal chromatin remodeling process involved in certain cancers. In this study, we constructed a large dataset to predict the activity value of HDAC1 inhibitors. Each compound was represented with seven fingerprints, and computational models were subsequently developed to predict HDAC1 inhibitors via five machine learning methods. These methods include naïve Bayes, κ-nearest neighbor, C4.5 decision tree, random forest, and support vector machine (SVM) algorithms. The best predicting model was CDK fingerprint with SVM, which exhibited an accuracy of 0.89. This model also performed best in five-fold cross-validation. Some representative substructure alerts responsible for HDAC1 inhibitors were identified by using MoSS in KNIME, which could facilitate the identification of HDAC1 inhibitors.

The Impact of Nutrition and Environmental Epigenetics on Human Health and Disease

Environmental epigenetics describes how environmental factors affect cellular epigenetics and, hence, human health. Epigenetic marks alter the spatial conformation of chromatin to regulate gene expression. Environmental factors with epigenetic effects include behaviors, nutrition, and chemicals and industrial pollutants. Epigenetic mechanisms are also implicated during development in utero and at the cellular level, so environmental exposures may harm the fetus by impairing the epigenome of the developing organism to modify disease risk later in life. By contrast, bioactive food components may trigger protective epigenetic modifications throughout life, with early life nutrition being particularly important. Beyond their genetics, the overall health status of an individual may be regarded as an integration of many environmental signals starting at gestation and acting through epigenetic modifications. This review explores how the environment affects the epigenome in health and disease, with a particular focus on cancer. Understanding the molecular effects of behavior, nutrients, and pollutants might be relevant for developing preventative strategies and personalized heath programs. Furthermore, by restoring cellular differentiation, epigenetic drugs could represent a potential strategy for the treatment of many diseases including cancer.

SARC018_SPORE02: Phase II Study of Mocetinostat Administered with Gemcitabine for Patients with Metastatic Leiomyosarcoma with Progression or Relapse following Prior Treatment with Gemcitabine-Containing Therapy

Histone deacetylase inhibitors (HDACi) can reverse chemoresistance, enhance chemotherapy-induced cytotoxicity, and reduce sarcoma proliferation in cell lines and animal models. We sought to determine the safety and toxicity of mocetinostat and its ability to reverse chemoresistance when administered with gemcitabine in patients with metastatic leiomyosarcoma resistant to prior gemcitabine-containing therapy. Participants with metastatic leiomyosarcoma received mocetinostat orally, 70 mg per day, three days per week, increasing to 90 mg after three weeks if well tolerated. Gemcitabine was administered at 1,000 mg/m² intravenously at 10 mg/m²/minute on days five and 12 of every 21-day cycle. Disease response was evaluated with CT or MRI. Twenty participants with leiomyosarcoma were evaluated for toxicity. Median time to disease progression was 2.0 months (95% CI 1.54–3.12). Eighteen participants were evaluated for radiologic response by RECIST 1.1. Best responses included one PR and 12 SD. Tumor size reduced in 3 patients. Most common toxicities were fatigue, thrombocytopenia, anemia, nausea, and anorexia. One patient experienced a significant pericardial adverse event. No study-related deaths were observed. Rechallenging with gemcitabine by adding mocetinostat was feasible and demonstrated modest activity in patients with leiomyosarcoma. Further studies are needed to better define the role of HDAC inhibitors in patients with metastatic leiomyosarcoma.

Silencing SATB1 overcomes temozolomide resistance by downregulating MGMT expression and upregulating SLC22A18 expression in human glioblastoma cells

Glioblastoma multiforme (GBM) is the most common malignant tumor of the central nervous system and has a very poor prognosis. Currently, patients were treated by resection followed by radiotherapy plus concurrent temozolomide (TMZ) chemotherapy. However, many patients are resistant to TMZ-induced DNA damage because of upregulated expression of the DNA repair enzyme O⁶-methylguanine-DNA methyltransferase (MGMT). In this study, upregulation of SATB1 and MGMT, and downregulation of SLC22A18 resulted in acquisition of TMZ resistance in GBM U87 cells. Inactivation of special AT-rich sequence-binding protein 1 (SATB1) using short hairpin RNA (shRNA) downregulated MGMT expression and upregulated solute carrier family 22 member 18 (SLC22A18) expression in GBM cells. This suggested SATB1-mediated posttranscriptional regulation of the MGMT and SLC22A18 protein levels. Immunohistochemical analysis of malignant glioma specimens demonstrated a significant positive correlation between the levels of MGMT and SATB1, and a negative correlation between the levels of SLC22A18 and SATB1. Importantly, in recurrent, compared with the primary, lesions in 15 paired identical tumors, the SATB1 and MGMT protein levels were increased and the SLC22A18 levels were decreased. Finally, in TMZ-resistant GBM, SATB1 knockdown enhanced TMZ efficacy. Consequently, SATB1 inhibition might be a promising strategy combined with TMZ chemotherapy to treat TMZ-resistant GBM.

PAK5 promotes the migration and invasion of cervical cancer cells by phosphorylating SATB1

p21-activated kinase 5 (PAK5) is involved in several oncogenic signaling pathways and its amplification or overexpression has been found in various types of cancer; however, the pathophysiologic role of PAK5 in cervical cancer (CC) remains elusive. This study aims to elucidate the effects of PAK5 on CC metastasis and its specific regulation mechanism. We performed western blotting and immunohistochemistry (IHC) analysis and found that the expression levels of PAK5 were significantly upregulated in CC cells and tissues. In addition, statistical analysis via IHC showed that increased PAK5 significantly correlated with CC progression. Mn²⁺-Phos-tag SDS-PAGE, western blotting, immunofluorescence and dual luciferase reporter assays were utilized to determine the involvement of SATB1 in PAK5-mediated epithelial-mesenchymal transition (EMT). We found that PAK5-mediated special AT-rich binding protein-1 (SATB1) phosphorylation on Ser47 initiated EMT cascade and promoted migration and invasion of CC cells. Furthermore, overexpression of PAK5 induced lung metastasis of CC cells in xenograft modes. Taken together, we conclude that PAK5 is a novel prognostic indicator and plays an important role in the CC metastasis.

Histone deacetylases as targets for antitrypanosomal drugs

Parasitic protozoa comprise several species that are causative agents of important diseases. These diseases are distributed throughout the world and include leishmaniasis, Chagas disease and sleeping sickness, malaria and toxoplasmosis. Treatment is based on drugs that were developed many years ago, which have side effects and produce resistant parasites. One approach for the development of new drugs is the identification of new molecular targets. We summarize the data on histone deacetylases, a class of enzymes that act on histones, which are closely associated with DNA and its regulation. These enzymes may constitute new targets for the development of antiparasitic protozoa drugs. Although several protozoan species are mentioned, members of the Trypanosomatidae family are the main focus of this short review.

Parasitic protozoa comprise species that are causative agents of important diseases distributed throughout the world. The available drugs for treatment were developed many years ago, might cause side effects and produce resistant parasites. The identification of new molecular targets is required for the development of new drugs. Histone deacetylases act on histones, are closely associated with DNA and thus may constitute new targets for antiparasitic therapy, especially that against trypanosomatid protozoa.

Prognostic and Clinicopathological Significance of SATB1 in Colorectal Cancer: A Meta-Analysis

Background: A large number of studies have reported the aberrant expression of special AT-rich sequence binding protein 1 (SATB1) in colorectal cancer (CRC). However, the role of SATB1 in CRC is still controversial. Therefore, we performed this meta-analysis to elucidate the prognostic and clinical value of SATB1 in CRC patients.

Methods: We searched Web of Science, EMBASE and PubMed entirely in January 2018 to identify related articles. Pooled Hazard ratio (HR) was adopted to evaluate the prognostic value of SATB1 in CRC and odd ratio (OR) was used to assess the clinicopathological significance of SATB1 in CRC.

Results: Ten eligible studies containing 7 on prognosis and 9 on clinicopathological characteristics were finally included in the present meta-analysis. Results revealed that patients with high expression of SATB1 tended to have shorter overall survival (OS) (pooled HR: 1.64, 95% CI: 1.04–2.57). Besides, we also discovered that the expression of SATB1 was associated with histologic grade (OR = 1.88, 95% CI: 1.06–3.34), distant metastasis (OR = 1.43, 95% CI: 1.11–1.85) and lymph node metastasis (OR = 1.50, 95% CI: 1.03–2.19).

Conclusion: Broadly speaking, our meta-analysis demonstrated that high expression level of SATB1 was related to poor prognosis in CRC patients.

Hydroxamic acid derivatives as histone deacetylase inhibitors: a DFT study of their tautomerism and metal affinities/selectivities

Hydroxamic acids are regarded as potent inhibitors of histone deacetylases (HDAC), and can therefore be used to reduce malignancy growth and size in affected organisms. Although there is a substantial body of information on the structures, syntheses, and biological activities of HDAC inhibitors, several important questions regarding their physicochemical properties and metal affinities/selectivities remain answered. First, how do the conformation and ionization of the hydroxamic group depend on its chemical composition and the dielectric properties of the medium? Second, how do these factors affect the affinities and selectivities of HDAC inhibitors for essential biogenic metal cations? Third, what is the preferred deprotonation site of the hydroxamic moiety and its mode of binding to the metal cation? The present work addressed these questions by performing density functional calculations combined with polarizable continuum model computations. The geometry, deprotonation pattern, metal-binding mode, and metal affinity/selectivity of SAHA, a typical HDAC inhibitor, were examined, and key factors affecting its ligation properties were elucidated. Sulfur- and selenium-containing analogs of SAHA were also modeled for the first time, and their potential as efficient metal-binding entities (to Mg²⁺, Fe²⁺, and Zn²⁺ cations) was assessed. The present calculations shed light on the thermodynamics of the binding of HDAC inhibitors to metal ions, and suggest techniques for enhancing their metal-ligating properties.

Histone hypo-acetylation of Sox9 mediates nicotine-induced weak cartilage repair by suppressing BMSC chondrogenic differentiation

BACKGROUND

Nicotine has negative effects on tissue repair, little research concerns its effect on the cartilage repair of tissue engineering stem cells. The present study aimed to investigate the effects of nicotine on the bone marrow-derived mesenchymal stem cells' (BMSCs) chondrogenic repair function of cartilage defects and explored the molecular mechanism.

METHODS

A cartilage defect model of rat was repaired by BMSC transplantation, and treated with nicotine or saline at 2.0 mg/kg/d in 12 weeks. Nicotine's effect on chondrogenic differentiation was studied by exposing BMSCs to nicotine at 0.1, 1, 10, and 100 μM, and methyllycaconitine (MLA), which is a selective α7-nicotinic acetylcholine receptor (nAChR) inhibitor and si-RNA of nuclear factor of activated T cells 2 (NFATc2), were used to verify the molecular mechanism of nicotine's effect.

RESULTS

Data showed that nicotine inhibited cartilage repair function by suppressing SRY-type high-mobility group box 9 (Sox9) in regenerated tissues. Further in vitro study demonstrated that nicotine enhanced intracellular Ca²⁺ and activity of calcineurin (CaN) through α7-nAChR, increased the nucleic expressions of NFATc2 and the bindings to SOX9 promoter, and thus reduced the acetylation of H3K9 and H3K14 in SOX9 promoter.

CONCLUSIONS

Findings from this study demonstrated that nicotine suppressed the chondrogenic differentiation of BMSCs in vivo and in vitro, which offers insight into the risk assessment of cartilage defect repair in a nicotine exposure population and its therapeutic target.

Novel role and regulation of HDAC4 in cocaine-related behaviors

Epigenetic mechanisms have been proposed to contribute to persistent aspects of addiction-related behaviors. One family of epigenetic molecules that may regulate maladaptive behavioral changes produced by cocaine use are the histone deacetylases (HDACs)-key regulators of chromatin and gene expression. In particular, the class IIa HDACs (HDAC4, HDAC5, HDAC7 and HDAC9) respond to changes in neuronal activity by modulating their distribution between the nucleus and cytoplasm-a process controlled in large part by changes in phosphorylation of conserved residues. Cocaine triggers a transient nuclear accumulation of HDAC5 that functions to limit the development of cocaine reward behavior. However, the role and regulation of the close family member, HDAC4, in cocaine behaviors remain largely unknown. In this study, we report that cocaine and cAMP signaling in striatum produced differential phosphorylation and subcellular localization of HDAC4 and HDAC5. Unlike HDAC5, cocaine exposure induced a modest hyperphosphorylation and nuclear export of HDAC4. Genetic deletion of HDAC4 in the nucleus accumbens reduced acute cocaine-produced locomotion, maximum locomotor sensitization and cocaine reward-related behavior. Interestingly, overexpression of an HDAC4 cytoplasm-concentrated mutant (S266E) increased cocaine reward behavior in the cocaine conditioned place preference assay, suggesting that cocaine-induced nuclear export of HDAC4 might function to facilitate the development of cocaine reward behaviors through a role in the cell cytoplasm. Together, our findings suggest that, despite high sequence homology, HDAC4 and HDAC5 are oppositely regulated by cocaine-induced signaling in vivo and have distinct roles in regulating cocaine behaviors.

[Role of SMU.2055 gene in regulating acid resistance of Streptococcus mutans UA159]

OBJECTIVE

To evaluate the effect of SMU.2055 gene on acid resistance of Streptococcus mutans.

METHODS

A SMU.2055-dificient mutant strain of S. mutans was constructed using homologous recombination technique. The growth of the wild-type and mutant strains was monitored in both normal and acidic conditions. The lethal pH level, glycolysis, proton permeability, cell permeability and biofilm formation of the two strains were compared.

RESULTS

PCR and sequence analyses verified the successful construction of the SMU.2055-dificient mutant strain. The growth and biofilm formation capacity of the mutant strain were obviously lowered in both normal and acidic conditions. The mutant strain also showed increased lethal pH level, proton permeability, and cell permeability with impaired H⁺-ATPase activity in acidic conditions, but its minimum glycolytic pH remained unaffected.

CONCLUSION

The SMU.2055-deficient S. mutans mutant exhibits a lowered acid resistance, which affects the growth, lethal pH, proton permeability, H⁺-ATPase activity, cell permeability and biofilm formation but not the minimum glycolytic pH of the mutant strain.

Trichostatin A Restores Expression of Adherens and Tight Junction Proteins during Transforming Growth Factor β-Mediated Epithelial-to-Mesenchymal Transition

Purpose:

Adherens junctions and polarity markers play an important role in maintaining epithelial phenotype but get altered during the epithelial-mesenchymal transition (EMT). Alterations of these markers during EMT of lens epithelial cell (LEC) can lead to vision compromising conditions. The aim of this study was to examine if Trichostatin-A (TSA), a histone deacetylase inhibitor, can prevent EMT by restoring the adherens junction complex in LEC.

Methods:

Fetal human lens epithelial cell line (FHL124) was used. Cells were treated with 10 ng/ml TGF-β2 in the presence or absence of TSA. Real time-PCR and western blotting were carried out for HDAC1, HDAC2, CDH1 (E-cad), TJP1 (ZO-1) and CTNNB1 (β-cat). Level of histone acetylation was analyzed by western blotting. Chromatin Immunoprecipitation was carried out to study the level of acetylated histone H4 and HDAC2 at the promoter regions of CDH1, TJP1, and CTNNB1. E-cad, ZO-1, and β-cat were localized using immunofluorescence. Kruskal-Wallis test was used for statistical analysis.

Results:

TSA down-regulated HDAC1 and HDAC2 and led to an increase in global acetylation. The mRNA and protein levels of E-cad, ZO-1, and β-cat decreased during EMT but were up-regulated by TSA treatment. TSA also helped in stabilizing these proteins at cell-cell junctions during EMT. TSA decreases association of HDAC2 at the promoter regions of adherens junction genes while increasing histone H4 acetylation status.

Conclusion:

TSA increases histone acetylation and restores the adherens junction complex in LECs. TSA helps in preventing EMT and thus shows potential against lens fibrosis and vision compromising conditions.

HDAC1 controls CIP2A transcription in human colorectal cancer cells

This work describes the effectiveness of HDAC-inhibitor (S)-2 towards colorectal cancer (CRC) HCT116 cells in vitro by inducing cell cycle arrest and apoptosis, and in vivo by contrasting tumour growth in mice xenografts. Among the multifaceted drug-induced events described herein, an interesting link has emerged between the oncoprotein histone deacetylase HDAC1 and the oncogenic Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A) which is overexpressed in several cancers including CRCs. HDAC1 inhibition by (S)-2 or specific siRNAs downregulates CIP2A transcription in three different CRC cell lines, thus restoring the oncosuppressor phosphatase PP2A activity that is reduced in most cancers. Once re-activated, PP2A dephosphorylates pGSK-3β(ser9) which phosphorylates β-catenin that remains within the cytosol where it undergoes degradation. The decreased amount/activity of β-catenin transcription factor prompts cell growth arrest by diminishing c-Myc and cyclin D1 expression and abrogating the prosurvival Wnt/β-catenin signaling pathway. These results are the first evidence that the inhibition of HDAC1 by (S)-2 downregulates CIP2A transcription and unleashes PP2A activity, thus inducing growth arrest and apoptosis in CRC cells.

Phenylbutyrate and β-cell function: contribution of histone deacetylases and ER stress inhibition

Incidences of diabetes are increasing globally due to involvement of genetic and epigenetic factors. Phenylbutyrate (PBA) is a US FDA approved drug for treatment of urea cycle disorder in children. PBA reduces endoplasmic reticulum (ER) stress and is proven as a potent histone deacetylases (HDACs) inhibitor. Chronic ER stress results in unfolding protein response, which triggers apoptosis. Abnormal ER homoeostasis is responsible for defective processing of several genes/proteins and contributes to β-cell death/failure. Accumulated evidences indicated that HDACs modulate key biochemical pathways and HDAC inhibitors improve β-cell function and insulin resistance by modulating multiple targets. This review highlights the role of PBA on β-cell functions, insulin resistance for possible treatment of diabetes through inhibition of ER stress and HDACs.

CBP/p300 Bromodomains Regulate Amyloid-like Protein Aggregation upon Aberrant Lysine Acetylation

Lysine acetylation is becoming increasingly recognized as a general biological principle in cellular homeostasis, and is subject to abnormal control in different human pathologies. Here, we describe a global effect on amyloid-like protein aggregation in human cells that results from aberrant lysine acetylation. Bromodomain reader proteins are involved in the aggregation process and, using chemical biology and gene silencing, we establish that p300/CBP bromodomains are necessary for aggregation to occur. Moreover, protein aggregation disturbs proteostasis by impairing the ubiquitin proteasome system (UPS) and protein translation, resulting in decreased cell viability. p300/CBP bromodomain inhibitors impede aggregation, which coincides with enhanced UPS function and increased cell viability. Aggregation of a pathologically relevant form of huntingtin protein is similarly affected by p300/CBP inhibition. Our results have implications for understanding the molecular basis of protein aggregation, and highlight the possibility of treating amyloid-like pathologies and related protein folding diseases with bromodomain inhibitor-based strategies.

The histone deacetylase inhibitor romidepsin synergizes with lenalidomide and enhances tumor cell death in T-cell lymphoma cell lines

We investigated the cytotoxic interactions of romidepsin, a histone deacetylase inhibitor, and lenalidomide, an immunomodulatory agent, in a T-cell lymphoma preclinical model. Hut-78 and Karpas-299 cells were treated with romidepsin and lenalidomide alone and in combination. The interaction between romidepsin and lenalidomide was evaluated by the Chou-Talalay method, and cell viability and clonogenicity were also evaluated. Apoptosis, reactive oxygen species (ROS) levels, and cell cycle distribution were determined by flow cytometry. ER stress, caspase activation, and the AKT, MAPK/ERK, and STAT-3 pathways were analyzed by Western blot. Combination treatment with romidepsin and lenalidomide had a synergistic effect in Hut-78 cells and an additive effect in Karpas-299 cells at 24 hours and did not decrease the viability of normal peripheral blood mononuclear cells. This drug combination induced apoptosis, increased ROS production, and activated caspase-8, -9, -3 and PARP. Apoptosis was associated with increased hallmarks of ER stress and activation of UPR sensors and was mediated by dephosphorylation of the AKT, MAPK/ERK, and STAT3 pathways.The combination of romidepsin and lenalidomide shows promise as a possible treatment for T-cell lymphoma. This work provides a basis for further studies.

Virtual screening and experimental validation of novel histone deacetylase inhibitors

Background

Histone deacetylases (HDACs) are promising therapeutic targets for the treatment of cancer, diabetes and other human diseases. HDAC inhibitors, as a new class of potential therapeutic agents, have attracted a great deal of interest for both research and clinical applications. Increasing efforts have been focused on the discovery of HDAC inhibitors and some HDAC inhibitors have been approved for use in cancer therapy. However, most HDAC inhibitors, including the clinically approved agents, do not selectively inhibit the deacetylase activity of class I and II HDAC isforms, and many suffer from metabolic instability. This study aims to identify new HDAC inhibitors by using a high-throughput virtual screening approach.

Methods

An integration of in silico virtual screening and in vitro experimental validation was used to identify novel HDAC inhibitors from a chemical database.

Results

A virtual screening workflow for HDAC inhibitors were created by integrating ligand- and receptor- based virtual screening methods. Using the virtual screening workflow, 22 hit compounds were selected and further tested via in vitro assays. Enzyme inhibition assays showed that three of the 22 compounds had HDAC inhibitory properties. Among these three compounds, ZINC12555961 significantly inhibited HDAC activity. Further in vitro experiments indicated that ZINC12555961 can selectively inhibit proliferation and promote apoptosis of cancer cells.

Conclusions

In summary, our study presents three new and potent HDAC inhibitors and one of these HDAC inhibitors shows anti-proliferative and apoptosis-inducing activity against various cancer cell lines. These results suggest that the developed virtual screening workflow can provide a useful source of information for the screening and validation of new HDAC inhibitors. The new-found HDAC inhibitors are worthy to further and more comprehensive investigations.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-016-0075-8) contains supplementary material, which is available to authorized users.

Biology and management of clear cell sarcoma: state of the art and future perspectives

INTRODUCTION

Clear cell sarcoma (CCS) is an aggressive tumor, typically developing in tendons or aponeuroses. The outcome of this orphan disease is poor, with 5-year and 10-year survival rates of localized CCS around 60-70% and 40-50%. Once the disease has metastasized, it is usually fatal due to its chemotherapy-resistant nature. Systemic treatment options are poorly standardized and the use of chemotherapy is based on weak scientific evidence.

AREAS COVERED

In this review, we systematically discuss the current scientific evidence for the systemic treatment of CCS, including tyrosine kinase inhibitors, immunotherapy and MET inhibitors. Expert commentary: Recent insights in the biology of CCS have identified new potential therapeutic targets, which should be tested in prospective clinical trials. Whenever possible, patients with metastatic CCS should be included in clinical trials with good biological rationale. Innovative trial methodology and new regulatory mechanisms are required to provide patients with uncommon cancers with active drugs.

SATB1 promotes prostate cancer metastasis by the regulation of epithelial-mesenchymal transition

Special AT-rich sequence binding protein 1 (SATB1) plays important role in the regulation of chromatin structure and gene expression. Recent studies have indicated oncogenic role of SATB1. However, the function of SATB1 in prostate cancer progression and metastasis remains unclear. In this study SATB1 expression vector or siRNA was employed to modulate the expression level of SATB1 in prostate cancer cells and xenograft tumor in nude mouse model. Immunohistochemical analysis was performed on clinical prostate cancer samples. Silencing SATB1 inhibited the growth of DU-145 cells subcutaneous tumor in nude mice, while SATB1 overexpression promoted the growth of LNCaP cells subcutaneous tumor in nude mice. Immunohistochemical and Western blot analysis of the xenografts showed that silencing SATB1 led to decreased expression of vimentin and MMP2 and increased expression of E-cadherin, while SATB1 overexpression led to increased expression of vimentin and MMP2 and decreased expression of E-cadherin. Furthermore, SATB1, vimentin and MMP2 expression was increased significantly while E-cadherin expression was reduced significantly in clinical samples of prostate carcinoma with metastasis compared to prostate carcinoma without metastasis and benign prostate hyperplasia. Taken together, these findings suggest that the modulation of epithelial-mesenchymal transition by SATB1 may contribute to prostate cancer metastasis.

A correlation analysis between HDAC1 over-expression and clinical features of laryngeal squamous cell carcinoma

CONCLUSION

HDAC1 may be a prognostic biomarker for LSCC malignant potency and a potent factor resulting in decreased sensitivity of LSCC in radiotherapy.

OBJECTIVE

The aim of this study was to evaluate the correlation between histone deacetylase 1 (HDAC1) over-expression and clinical features in laryngeal squamous cell carcinoma (LSCC).

METHODS

This study assessed the HDAC1 expressions in 90 formalin-fixed paraffin-embedded LSCC samples, 30 adjacent non-neoplastic tissues, and 30 laryngeal polyp tissues by immunohistochemistry (IHC). In addition, another 40 LSCC samples were collected that were divided into two groups after 3-month radiotherapy: the high radio-sensitive group (HRS) and low radio-sensitive group (LRS). Overall survival curves of all the LSCC patients were constructed by Kaplan-Meier method and long-rank test.

RESULTS

All ninety samples were positively immunostained for HDAC1. The expression of HDAC1 was up-regulated and significantly associated with T classification, lymph node metastases, tumor location and clinical stage. HDAC1 was mainly labeled in the epithelial cells of laryngeal polyp tissues and adjacent non-neoplastic tissues. In addition, the expression of HDAC1 was significantly higher in LRS than that in HRS. The positive rates for stage III-IV tumor were significantly higher than those for stage II. LSCC patients with HDAC1 over-expression and LRS presented a shorter 5-year overall survival rate.