Novel histone deacetylase inhibitors in clinical trials as anti-cancer agents. J Hematol Oncol. 2010;3:5. [PMID: 20132536 PMCID: PMC2827364 DOI: 10.1186/1756-8722-3-5]

Histone deacetylase inhibitors for leukemia treatment: current status and future directions

Leukemia remains a major therapeutic challenge in clinical oncology. Despite significant advancements in treatment modalities, leukemia remains a significant cause of morbidity and mortality worldwide, as the current conventional therapies are accompanied by life-limiting adverse effects and a high risk of disease relapse. Histone deacetylase inhibitors have emerged as a promising group of antineoplastic agents due to their ability to modulate gene expression epigenetically. In this review, we explore these agents, their mechanisms of action, pharmacokinetics, safety and clinical efficacy, monotherapy and combination therapy strategies, and clinical challenges associated with histone deacetylase inhibitors in leukemia treatment, along with the latest evidence and ongoing studies in the field. In addition, we discuss future directions to optimize the therapeutic potential of these agents.

Stack-HDAC3i: A high-precision identification of HDAC3 inhibitors by exploiting a stacked ensemble-learning framework

Epigenetics involves reversible modifications in gene expression without altering the genetic code itself. Among these modifications, histone deacetylases (HDACs) play a key role by removing acetyl groups from lysine residues on histones. Overexpression of HDACs is linked to the proliferation and survival of tumor cells. To combat this, HDAC inhibitors (HDACi) are commonly used in cancer treatments. However, pan-HDAC inhibition can lead to numerous side effects. Therefore, isoform-selective HDAC inhibitors, such as HDAC3i, could be advantageous for treating various medical conditions while minimizing off-target effects. To date, computational approaches that use only the SMILES notation without any experimental evidence have become increasingly popular and necessary for the initial discovery of novel potential therapeutic drugs. In this study, we develop an innovative and high-precision stacked-ensemble framework, called Stack-HDAC3i, which can directly identify HDAC3i using only the SMILES notation. Using an up-to-date benchmark dataset, we first employed both molecular descriptors and Mol2Vec embeddings to generate feature representations that cover multi-view information embedded in HDAC3i, such as structural and contextual information. Subsequently, these feature representations were used to train baseline models using nine popular ML algorithms. Finally, the probabilistic features derived from the selected baseline models were fused to construct the final stacked model. Both cross-validation and independent tests showed that Stack-HDAC3i is a high-accuracy prediction model with great generalization ability for identifying HDAC3i. Furthermore, in the independent test, Stack-HDAC3i achieved an accuracy of 0.926 and Matthew's correlation coefficient of 0.850, which are 0.44-6.11% and 0.83-11.90% higher than its constituent baseline models, respectively.

Dual role of Nrf2 signaling in hepatocellular carcinoma: promoting development, immune evasion, and therapeutic challenges

Hepatocellular carcinoma (HCC) is the predominant form of liver cancer and ranks as the third leading cause of cancer-related mortality globally. The liver performs a wide range of tasks and is the primary organ responsible for metabolizing harmful substances and foreign compounds. Oxidative stress has a crucial role in growth and improvement of hepatocellular carcinoma (HCC). Nuclear factor erythroid 2 (1)-related factor 2 (Nrf2) is an element that regulates transcription located in the cytoplasm. It controls the balance of redox reactions by stimulating the expression of many genes that depend on antioxidant response elements. Nrf2 has contrasting functions in the normal, healthy liver and HCC. In the normal liver, Nrf2 provides advantageous benefits, while in HCC it promotes harmful effects that support the growth and survival of HCC. Continuous activation of Nrf2 has been detected in HCC and promotes its advancement and aggressiveness. In addition, Activation of Nrf2 may lead to immune evasion, weakening the immune cells' ability to attack tumors and thereby promoting tumor development. Furthermore, chemoresistance in HCC, which is considered a form of stress response to chemotherapy medications, significantly impedes the effectiveness of HCC treatment. Stress management is typically accomplished by activating specific signal pathways and chemical variables. One important element in the creation of chemoresistance in HCC is nuclear factor-E2-related factor 2 (Nrf2). Nrf2 is a transcription factor that regulates the activation and production of a group of genes that encode proteins responsible for protecting cells from damage. This occurs through the Nrf2/ARE pathway, which is a crucial mechanism for combating oxidative stress within cells.

Hi-GeoMVP: a hierarchical geometry-enhanced deep learning model for drug response prediction

MOTIVATION

Personalized cancer treatments require accurate drug response predictions. Existing deep learning methods show promise but higher accuracy is needed to serve the purpose of precision medicine. The prediction accuracy can be improved with not only topology but geometrical information of drugs.

RESULTS

A novel deep learning methodology for drug response prediction is presented, named Hi-GeoMVP. It synthesizes hierarchical drug representation with multi-omics data, leveraging graph neural networks and variational autoencoders for detailed drug and cell line representations. Multi-task learning is employed to make better prediction, while both 2D and 3D molecular representations capture comprehensive drug information. Testing on the GDSC dataset confirms Hi-GeoMVP's enhanced performance, surpassing prior state-of-the-art methods by improving the Pearson correlation coefficient from 0.934 to 0.941 and decreasing the root mean square error from 0.969 to 0.931. In the case of blind test, Hi-GeoMVP demonstrated robustness, outperforming the best previous models with a superior Pearson correlation coefficient in the drug-blind test. These results underscore Hi-GeoMVP's capabilities in drug response prediction, implying its potential for precision medicine.

AVAILABILITY AND IMPLEMENTATION

The source code is available at https://github.com/matcyr/Hi-GeoMVP.

Reduction of Amyloid-β Production without Inhibiting Secretase Activity by MS-275

Brain amyloid-β (Aβ) governs the pathogenic process of Alzheimer's disease. Clinical trials to assess the disease-modifying effects of inhibitors or modulators of β- and γ-secretases have not shown clinical benefit and can cause serious adverse events. Previously, we found that the interleukin-like epithelial-to-mesenchymal transition inducer (ILEI, also known as FAM3C) negatively regulates the Aβ production through a decrease in Aβ immediate precursor, without the inhibition of β- and γ-secretase activity. Herein, we found that MS-275, a benzamide derivative that is known to inhibit histone deacetylases (HDACs), exhibits ILEI-like activity to reduce Aβ production independent of HDAC inhibition. Chronic MS-275 treatment decreased Aβ deposition in the cerebral cortex and hippocampus in an Alzheimer's disease mouse model. Overall, our results indicate that MS-275 is a potential therapeutic candidate for efficiently reducing brain Aβ accumulation.

Molecular simulations required to target novel and potent inhibitors of cancer invasion

INTRODUCTION

Computer-aided drug design (CADD) is a computational approach used to discover, develop, and analyze drugs and active molecules with similar biochemical properties. Molecular simulation technology has significantly accelerated drug research and reduced manufacturing costs. It is an optimized drug discovery method that greatly improves the efficiency of novel drug development processes.

AREASCOVERED

This review discusses the development of molecular simulations of effective cancer inhibitors and traces the main outcomes of in silico studies by introducing representative categories of six important anticancer targets. The authors provide views on this topic from the perspective of both medicinal chemistry and artificial intelligence, indicating the major challenges and predicting trends.

EXPERT OPINION

The goal of introducing CADD into cancer treatment is to realize a highly efficient, accurate, and desired approach with a high success rate for identifying potent drug candidates. However, the major challenge is the lack of a sophisticated data-filtering mechanism to verify bottom data from mixed-quality references. Consequently, despite the continuous development of algorithms, computer power, and interface optimization, specific data filtering mechanisms will become an urgent and crucial issue in the future.

Long-term follow-up results and treatment outcomes of children and adults with resistance to thyroid hormone alpha

PURPOSE

Resistance to thyroid hormone alpha (RTHα) is a rare entity and has no specific treatment. To date, mostly levothyroxine has been used, but there is a lack of knowledge about the long-term outcomes of this treatment. We aimed to evaluate the long-term follow-up results and treatment outcomes of children and their parents diagnosed with RTHα.

METHODS

Four children [the median (minimum-maximum) age at diagnosis, 4.5 (1.4-9.5) years] and three adults [age at diagnosis, 31.7 (28.0-35.3) years] from two families were included in the study, who had RTHα and followed up between 2014 and 2021.

RESULTS

The median duration of treatment was 6.7 (5.9-8.0) years, and the levothyroxine dose at the final visit was 1.4 (1.2-2.2) and 1.9 (1.2-2.4) mcg/kg/day for adults and pediatric patients, respectively. Treatment ameliorated constipation in all patients with this complaint (n = 5). Normal mental functions were achieved and IQ scores improved in most children except one (age at diagnosis, 9.5 years). At the final visit, creatine kinase levels relative to the reference upper limit were significantly lower compared to the pre-treatment ratios [0.9 (0.2-1.3) vs. 1.3 (0.5-1.6), p = 0.028]. Anemia was present in five patients at diagnosis, which resolved in one adult patient but occurred in one child despite treatment (p = 0.999). A minimal pericardial effusion persisted in one pediatric patient.

CONCLUSIONS

We demonstrated that constipation was ameliorated, neuromotor development of some children was improved, and creatine kinase levels were diminished with levothyroxine treatment in patients with RTHα, while some features including anemia did not resolve.

HDAC inhibitor ITF2357 reduces resistance of mutant-KRAS non-small cell lung cancer to pemetrexed through a HDAC2/miR-130a-3p-dependent mechanism

BACKGROUND

Histone deacetylases (HDAC) contribute to oncogenic program, pointing to their inhibitors as a potential strategy against cancers. We, thus, studied the mechanism of HDAC inhibitor ITF2357 in resistance of mutant (mut)-KRAS non-small cell lung cancer (NSCLC) to pemetrexed (Pem).

METHODS

We first determined the expression of NSCLC tumorigenesis-related HDAC2 and Rad51 in NSCLC tissues and cells. Next, we illustrated the effect of ITF2357 on the Pem resistance in wild type-KARS NSCLC cell line H1299, mut-KARS NSCLC cell line A549 and Pem-resistant mut-KARS cell line A549R in vitro and in xenografts of nude mice in vivo.

RESULTS

Expression of HDAC2 and Rad51 was upregulated in NSCLC tissues and cells. Accordingly, it was revealed that ITF2357 downregulated HDAC2 expression to diminish the resistance of H1299, A549 and A549R cells to Pem. HDAC2 bound to miR-130a-3p to upregulate its target gene Rad51. The in vitro findings were reproduced in vivo, where ITF2357 inhibited the HDAC2/miR-130a-3p/Rad51 axis to reduce the resistance of mut-KRAS NSCLC to Pem.

CONCLUSION

Taken together, HDAC inhibitor ITF2357 restores miR-130a-3p expression by inhibiting HDAC2, thereby repressing Rad51 and ultimately diminishing resistance of mut-KRAS NSCLC to Pem. Our findings suggested HDAC inhibitor ITF2357 as a promising adjuvant strategy to enhance the sensitivity of mut-KRAS NSCLC to Pem.

Potential of histone deacetylase inhibitors in the control and regulation of prostate, breast and ovarian cancer

Histone deacetylases (HDACs) are enzymes that play a role in chromatin remodeling and epigenetics. They belong to a specific category of enzymes that eliminate the acetyl part of the histones' -N-acetyl lysine, causing the histones to be wrapped compactly around DNA. Numerous biological processes rely on HDACs, including cell proliferation and differentiation, angiogenesis, metastasis, gene regulation, and transcription. Epigenetic changes, specifically increased expression and activity of HDACs, are commonly detected in cancer. As a result, HDACi could be used to develop anticancer drugs. Although preclinical outcomes with HDACs as monotherapy have been promising clinical trials have had mixed results and limited success. In both preclinical and clinical trials, however, combination therapy with different anticancer medicines has proved to have synergistic effects. Furthermore, these combinations improved efficacy, decreased tumor resistance to therapy, and decreased toxicity. In the present review, the detailed modes of action, classification of HDACs, and their correlation with different cancers like prostate, breast, and ovarian cancer were discussed. Further, the different cell signaling pathways and the structure-activity relationship and pharmaco-toxicological properties of the HDACi, and their synergistic effects with other anticancer drugs observed in recent preclinical and clinical studies used in combination therapy were discussed for prostate, breast, and ovarian cancer treatment.

Valproic Acid Inhibits Peripheral T Cell Lymphoma Cells Behaviors via Restraining PI3K/AKT Pathway

Objective

Alproic acid (VPA) is a clinic antiepileptic drug. Antitumor role of VPA has been studied. The aim of this study was to clarify the treatment effect and potential mechanism of VPA on peripheral T cell lymphomas (PTCLs).

Materials and Methods

Hut 78 cells were obtained from the Shanghai Cell Bank, Chinese Academy of Sciences, and randomly divided into six groups: control, VPA (8 mM), empty vector (NC), miR-3196 mimics, miR-3196 inhibitor, and VPA + miR-3196 mimics groups. CCK-8 assay was performed to clarify the regulative role of VPA on cell proliferation. Flow cytometry was applied to determine the apoptotic rate and ROS levels. miR-3196 was tested by RT-qPCR. Western blot was used to test the level of p-PI3K and p-AKT. Biochemical experiments were used to detect changes in the content of ATP, lactate level, and glucose content. Electron microscopy was used to show the structure of mitochondria in Hut 78 cells.

Results

VPA greatly promoted the expression of miR-3196 and inhibited cell proliferation in a dose-dependent manner. Compared with the NC group, the cell apoptosis rate, Bax and cleaved-caspase-3 expression, lactate level, ROS expression, and glucose content in the VPA group were significantly increased (P < 0.05), and cell proliferation, ATP production, and the expression of Bcl-2, p-PI3K and p-AKT was decreased significantly (P < 0.05). The role of mir-3196 mimics is similar to VPA. While, the miR-3196 inhibitor had the opposite effect to VPA and mimics. The combination of VPA and miR-3196 mimics has the most obvious effect.

Conclusion

VPA can inhibit the proliferation of Hut 78 cells and promote cell apoptosis and the structure and dysfunction of mitochondria by regulating the activity of the PI3K/AKT pathway.

Isoform selective versus non-selective histone deacetylase inhibitors in HIV latency reversal

HIV remains incurable due to the persistence of a latent viral reservoir found in HIV infected cells, primarily resting memory CD4+ T cells. Depletion of this reservoir may be the only way to end this deadly epidemic. In latency, the integrated proviral DNA of HIV is transcriptionally silenced partly due to the activity of histone deacetylases (HDACs). One strategy proposed to overcome this challenge, is the use of HDAC inhibitors as latency reversal agents to induce viral expression (shock) under the cover of antiretroviral therapy (ART). It is hoped that this will lead to elimination of the reservoir by immunologic and viral cytopathic (kill). However, there are 18 isoforms of HDACs leading to varying selectivity for HDAC inhibitors. Here we review HDAC inhibitors with emphasis on their selectivity for HIV latency reversal.

Recent Advances and Challenges in Uveal Melanoma Immunotherapy

Simple Summary

Uveal melanoma is the most common primary intraocular malignancy in adults. Although it can be controlled locally, half of the patients still develop metastases. To date, there have been no standard therapeutic strategies for the prevention or treatment of metastases. Existing therapies, such as chemotherapy and targeted therapies, induce only minimal responses. This review focuses on newly published research on immunotherapy. We highlight expanding treatments and their clinical outcomes, as well as propose promising new treatments and feasible checkpoints. Based on these findings, we provide innovative insights into feasible strategies for the treatment of patients with uveal melanoma.

Abstract

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Compared to cutaneous melanoma (CM), which mainly harbors BRAF or NRAS mutations, UM predominantly harbors GNAQ or GNA11 mutations. Although primary UM can be controlled locally, approximately 50% of patients still develop metastases. To date, there have been no standard therapeutic strategies for the prevention or treatment of metastases. Unfortunately, chemotherapy and targeted therapies only induce minimal responses in patients with metastatic UM, with a median survival time of only 4–5 months after metastasis detection. Immunotherapy agents, such as immune checkpoint inhibitors, have achieved pioneering outcomes in CM but have shown limited effects in UM. Researchers have explored several feasible checkpoints to identify options for future therapies. Cancer vaccines have shown little in the way of therapeutic benefit in patients with UM, and there are few ongoing trials providing favorable evidence, but adoptive cell transfer-related therapies seem promising and deserve further investigation. More recently, the immune-mobilizing monoclonal T-cell receptor against the cancer molecule tebentafusp showed impressive antitumor effects. Meanwhile, oncolytic viruses and small molecule inhibitors have also gained ground. This review highlights recent progress in burgeoning treatments and provides innovative insights on feasible strategies for the treatment of UM.

Efficacy and Safety Profile of Histone Deacetylase Inhibitors for Metastatic Breast Cancer: A Meta-Analysis

Introduction

Acquired resistance to endocrine therapy (ET) remains a big challenge in the management of metastatic breast cancer (MBC). A novel therapeutic agent, histone deacetylase inhibitors (HDACi), targets the abnormal epigenetic modification and may overcome acquired resistance. However, HDACi efficacy and the safety profile for hormone receptor (HoR)-positive/human epidermal growth factor receptor 2 (HER2)-negative MBC remain controversial.

Methods

Two independent reviewers searched PubMed, Embase, and Cochrane Central Register of Controlled Trials databases for relevant studies on HDACi and HoR+/HER2- MBC. Demographic and clinicopathological parameters were extracted and presented as means and proportions, and between-group differences were assessed by Pearson chi-square test. Fixed- or random-effects models were used for meta-analysis based on inter-study heterogeneity. Pooled results were presented as L’Abbé plot and forest plot. Funnel plot and Egger’s test were employed for evaluation of publication bias.

Results

Four studies with 1,457 patients were included for meta-analysis. The overall objective response rates (ORRs) of HDACi + ET (HE) and placebo + ET (PE) groups were 11.52% and 6.67%, respectively. The HE regimen significantly increased ORR (odds ratio [OR] 1.633, 95% confidence interval [CI] = 1.103–2.418, p < 0.05) and showed higher clinical benefit rate (CBR) than the PE regimen (HE vs. PE groups: 38.82% vs. 30.58%, OR 1.378, 95% CI = 1.020–1.861, p < 0.05). Additionally, the HE regimen was associated with prolonged progression-free survival (PFS) (hazard ratio [HR] 0.761, 95% CI = 0.650–0.872, p < 0.001) and overall survival (OS) (HR 0.849, 95% CI = 0.702–0.996, p < 0.001). Regarding safety profile, the HE regimen had increasing toxicity in terms of higher overall adverse event (AE), Grade ≥3 AE, dose modification, and discontinuation rate.

Conclusions

This meta-analysis validated that the HE regimen had superior efficacy over control in terms of ORR, CBR, PFS, and OS, but was accompanied with increasing toxicity. HDACi plus ET could serve as an important option in managing HoR+/HER2- MBC. Future studies may focus on the clinical difference among different HDACi and AE managements to enhance tolerability.

Effect of Sodium Butyrate on p16INK4a, p14ARF, p15INK4b, Class I HDACs (HDACs 1, 2, 3) Class II HDACs (HDACs 4, 5, 6), Cell Growth Inhibition and Apoptosis Induction in Pancreatic Cancer AsPC-1 and Colon Cancer HCT-116 Cell Lines

BACKGROUND

In higher eukaryotes, cell-cycle transitions are regulated by different cyclin-dependent kinases (Cdks) and Cdk inhibitors (CKIs). CKIs include two groups, the Ink4 (p16INK4a, p15INK4b, p18INK4c, and p19INK4d) and the Cip/Kip (p21Cip1, p27Kip1, and p57Kip2) families. The hyperactivity of histone deacetylases (HDACs) is associated with cancer induction. Histone deacetylase inhibitors (HDACIs) such as sodium butyrate (NaBT) can inhibit HDAC activity resulting in apoptosis induction. The present study was designed to investigate the effect of sodium butyrate on p16INK4a, p14ARF, p15INK4b, class I HDACs (HDACs 1, 2, 3), and class II HDACs (HDACs 4, 5, 6), cell growth inhibition, and apoptosis induction in pancreatic cancer AsPC-1 and colon cancer HCT-116 cell lines. In fact, we want to know whether sodium butyrate can reactivate Ink4 and Cip/Kip families by HDACs inhibition.

MATERIALS AND METHODS

The AsPC-1 and HCT-116 cells were treated with sodium butyrate at different periods. Then, the MTT assay, cell apoptosis assay, and qRT-PCR were done to determine viability, apoptosis, and the relative expression level of the genes respectively.

RESULTS

The sodium butyrate increased p16INK4a, p14ARF, and p15INK4b and decreased class I and II HDACs significantly. Besides, HCT-116 cell was more sensitive to sodium butyrate in comparison to AsPC-1 cell.

CONCLUSION

The sodium butyrate can reactivate the p16INK4a, p14ARF, and p15INK4b through inhibition of HDACs in AsPC-1 and HCT-116 cell lines.

Histone modifiers at the crossroads of oncolytic and oncogenic viruses

Cancer is a disease caused by loss of regulatory processes that control cell cycle, resulting in increased proliferation. The loss of control can deregulate both tumor suppressors and oncogenes. Apart from cell intrinsic gene mutations and environmental factors, infection by cancer-causing viruses also induces changes that lead to malignant transformation. This can be caused by both expression of oncogenic viral proteins and also by changes in cellular genes and proteins that affect the epigenome. Thus, these epigenetic modifiers are good therapeutic targets, and several epigenetic inhibitors are approved for the treatment of different cancers. In addition to small molecule drugs, biological therapies such as antibodies and viral therapies are also increasingly being used to treat cancer. An HSV-1 derived oncolytic virus is currently approved by the US FDA and the European Medicines Agency. Similarly, an adenovirus-based therapeutic is approved for use in China for some cancer types. Since viruses can affect cellular epigenetics, the interaction of epigenome-targeting drugs with oncogenic and oncolytic viruses is a highly significant area of investigation. Here we will review the current knowledge about the impact of using epigenetic drugs in tumors positive for oncogenic viruses or as therapeutic combinations with oncolytic viruses.

Discovery of phthalazino[1,2-b]-quinazolinone derivatives as multi-target HDAC inhibitors for the treatment of hepatocellular carcinoma via activating the p53 signal pathway

In view of histone deacetylases (HDACs) as a promising target for cancer therapy, a series of phthalazino[1,2-b]-quinazolinone units were hybrided with ortho-aminoanilide or hydroxamic acid to serve as multi-target HDAC inhibitors for the treatment of solid tumors. Among the target compounds, 8h possessed nano-molar IC50 values toward the tested cancer cells and HDAC subtypes, which was more potent than the HDAC inhibitor SAHA (vorinostat). Mechanism study revealed that compound 8h could suppress the HepG2 cell proliferation via prompting the acetylation of histone 3 (H3) and α-tubulin, and activating the p53 signal pathway as designed. In addition, compound 8h exhibited much stronger in vivo antitumor efficacy than SAHA in the HepG2 xenograft tumor model with negligible toxicity. As a novel multi-target HDAC inhibitor, compound 8h deserves further development as a potential anticancer agent.

Patient-derived organoids for personalized gallbladder cancer modelling and drug screening

BACKGROUND

Gallbladder carcinoma (GBC) is a relatively rare but highly aggressive cancer with late clinical detection and a poor prognosis. However, the lack of models with features consistent with human gallbladder tumours has hindered progress in pathogenic mechanisms and therapies.

METHODS

We established organoid lines derived from human GBC as well as normal gallbladder and benign gallbladder adenoma (GBA) tissues. The histopathology signatures of organoid cultures were identified by H&E staining, immunohistochemistry and immunofluorescence. The genetic and transcriptional features of organoids were analysed by whole-exome sequencing and RNA sequencing. A set of compounds targeting the most active signalling pathways in GBCs were screened for their ability to suppress GBC organoids. The antitumour effects of candidate compounds, CUDC-101 and CUDC-907, were evaluated in vitro and in vivo.

RESULTS

The established organoids were cultured stably for more than 6 months and closely recapitulated the histopathology, genetic and transcriptional features, and intratumour heterogeneity of the primary tissues at the single-cell level. Notably, expression profiling analysis of the organoids revealed a set of genes that varied across the three subtypes and thus may participate in the malignant progression of gallbladder diseases. More importantly, we found that the dual PI3K/HDAC inhibitor CUDC-907 significantly restrained the growth of various GBC organoids with minimal toxicity to normal gallbladder organoids.

CONCLUSIONS

Patient-derived organoids are potentially a useful platform to explore molecular pathogenesis of gallbladder tumours and discover personalized drugs.

Photodynamic antimicrobial chemotherapy coupled with the use of the photosensitizers methylene blue and temoporfin as a potential novel treatment for Staphylococcus aureus in burn infections

Photodynamic antimicrobial chemotherapy (PACT) is a novel alternative antimicrobial therapy that elicits a broad mechanism of action and therefore has a low probability of generating resistance. Such properties make PACT ideally suited for utilization in localized applications such as burn wounds. The aim of this study was to determine the antimicrobial activity of MB and temoporfin against both a S. aureus isolate and a P. aeruginosa isolate in light (640 nm) and dark conditions at a range of time points (0–20 min). A Staphylococcus aureus isolate and a Pseudomonas aeruginosa isolate were treated in vitro with methylene blue (MB) and temoporfin under different conditions following exposure to light at 640 nm and in no-light (dark) conditions. Bacterial cell viability [colony-forming units (c.f.u.) ml⁻¹] was then calculated. Against P. aeruginosa, when MB was used as the photosensitizer, no phototoxic effect was observed in either light or dark conditions. After treatment with temoporfin, a reduction of less than one log (7.00×10⁷ c.f.u. ml⁻¹) was observed in the light after 20 min of exposure. However, temoporfin completely eradicated S. aureus in both light and dark conditions after 1 min (where a seven log reduction in c.f.u. ml⁻¹ was observed). Methylene blue resulted in a loss of S. aureus viability, with a two log reduction in bacterial viability (c.f.u. ml⁻¹) reported in both light and dark conditions after 20 min exposure time. Temoporfin demonstrated greater antimicrobial efficacy than MB against both the S. aureus and P. aeruginosa isolates tested. At 12.5 µM temoporfin resulted in complete eradication of S. aureus. In light of this study, further research into the validity of PACT, coupled with the photosensitizers (such as temoporfin), should be conducted in order to potentially develop alternative antimicrobial treatment regimes for burn wounds.

Phase 1 trial of entinostat as monotherapy and combined with exemestane in Japanese patients with hormone receptor-positive advanced breast cancer

Background

Entinostat is an oral inhibitor of class I histone deacetylases intended for endocrine therapy-resistant patients with hormone receptor-positive (HR+) advanced or metastatic breast cancer (BC). We examined the safety, efficacy, and pharmacokinetics of entinostat monotherapy and combined entinostat/exemestane in Japanese patients.

Methods

This phase 1 study (3 + 3 dose-escalation design) enrolled postmenopausal women with advanced/metastatic HR+ BC previously treated with nonsteroidal aromatase inhibitors. Dose-limiting toxicities (DLTs) of entinostat monotherapy (3 mg/qw, 5 mg/qw, or 10 mg/q2w) and entinostat+exemestane (5 mg/qw + 25 mg/qd) were assessed. Pharmacokinetics, lysine acetylation (Ac-K), and T-cell activation markers were measured at multiple time points.

Results

Twelve patients were enrolled. No DLTs or grade 3–5 adverse events (AEs) occurred. Drug-related AEs (≥ 2 patients) during DLT observation were hypophosphatemia, nausea, and platelet count decreased. Six patients (50%) achieved stable disease (SD) for ≥ 6 months, including one treated for > 19 months. Median progression-free survival was 13.9 months (95% CI 1.9–not calculable); median overall survival was not reached. Area under the plasma concentration-time curve and Ac-K in peripheral blood CD19+ B cells increased dose-proportionally. The changing patterns of entinostat concentrations and Ac-K levels were well correlated. T-cell activation markers increased over time; CD69 increased more in patients with SD ≥ 6 months vs. SD < 6 months.

Conclusions

Entinostat monotherapy and combined entinostat/exemestane were well tolerated in Japanese patients, with no additional safety concerns compared with previous reports. The correlation between pharmacokinetics and Ac-K in peripheral blood CD19+ B cells, and also T-cell activation markers, merits further investigation.

Trial registration

JAPIC Clinical Trial Information, JapicCTI-153066. Registered 12 November 2015. ClinicalTrials.gov, NCT02623751. Registered 8 December 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08973-4.

In-Silico Analysis of Chromatin Modifiers and Profiling of Histone Deacetylases (HDAC's) in Human Oral Cancer

Histone modifications have been demonstrated to play a significant role in oral squamous cell carcinoma (OSCC) epigenetic regulation. An in-silico analysis of The Cancer Genome Atlas (TCGA) of various histone acetyl transferases (HATs) and histone deacetylases (HDACs) suggested that HATs do not differ between normal and tumor samples whereas HDAC2 and HDAC1 change maximally and marginally respectively between normal and tumor patients with no change being noted in HDAC6 expression. Hence, this investigation was carried out to validate the expression states of HDAC 1, 2 and 6 mRNAs in buccal mucosa and tongue SCC samples in an Indian cohort. Buccal mucosa and tongue squamous cell carcinoma tissues with intact histopathology were processed for RNA isolation followed by cDNA synthesis which was then subjected to q-PCR for HDACs. The average RNA yield of the tongue tissue sample was ∼2 µg/mg of tissue and the A_260/280 ratios were between 2.03 and 2.06. The average RNA yield of buccal mucosa tissue sample was ∼1 µg/mg of tissue and the A_260/280 ratio were between 2.00 and 2.08. We have demonstrated that HDAC2 was overexpressed in tongue and buccal mucosa samples. Over-expression of HDAC2 imply potential use of HDACi along with standard chemotherapeutic drug in oral cancer treatment.

Haloperidol Metabolite II Valproate Ester (S)-(-)-MRJF22: Preliminary Studies as a Potential Multifunctional Agent Against Uveal Melanoma

Increased angiogenesis and vascular endothelial growth factor (VEGF) levels contribute to higher metastasis and mortality in uveal melanoma (UM), an aggressive malignancy of the eye in adults. (±)-MRJF22, a prodrug of the sigma (σ) ligand haloperidol metabolite II conjugated with the histone deacetylase (HDAC) inhibitor valproic acid, has previously demonstrated a promising antiangiogenic activity. Herein, the asymmetric synthesis of (R)-(+)-MRJF22 and (S)-(-)-MRJF22 was performed to investigate their contribution to (±)-MRJF22 antiangiogenic effects in human retinal endothelial cells (HREC) and to assess their therapeutic potential in primary human uveal melanoma (UM) 92-1 cell line. While both enantiomers displayed almost identical capabilities to reduce cell viability than the racemic mixture, (S)-(-)-MRJF22 exhibited the highest antimigratory effects in endothelial and tumor cells. Given the fundamental contribution of cell motility to cancer progression, (S)-(-)-MRJF22 may represent a promising candidate for novel antimetastatic therapy in patients with UM.

Microtubule associated proteins as targets for anticancer drug development

The dynamic equilibrium of tubulin-microtubule is an essential aspect of cell survivality. Modulation of this dynamics has become an important target for the cancer drug development. Tubulin exists in the alpha-beta dimer form which polymerizes to form microtubule and further depolymerizes back to tubulin dimer. The microtubule plays an essential role in mitosis and cell multiplication. Antitubulin drugs disturb the microtubule dynamics which is essentially required for DNA segregation and cell division during mitosis so killing the cancerous cells. Microtubule Associated Proteins (MAPs) interact with cellular cytoskeletal microtubules. MAPs bind to the either polymerized or depolymerized tubulin dimers within the cell and mostly causing stabilization of microtubules. Some of the tubulin binding drugs are in clinical use and others in clinical trial. MAPs inhibitors are also in clinical trial. Post-translational modification of lysine-40 either in histone or in alpha tubulin has an important role in gene expression and is balanced between histone deacetylases (HDACs) and histone acetyltransferases (HATs). HDAC inhibitors have the anticancer properties to form a drug for the treatment of cancer. They act by inducing cell cycle arrest and cell death. Some of the HDAC inhibitors are approved to be used as anticancer drug while others are under different phases of clinical trial. The present review updates on various MAPs, their role in cancer progression, MAPs inhibitors and their future prospects.

Selective Histone Deacetylase Inhibitor ACY-241 (Citarinostat) Plus Nivolumab in Advanced Non-Small Cell Lung Cancer: Results From a Phase Ib Study

BACKGROUND

Histone deacetylase (HDAC) overexpression has been documented in various cancers and may be associated with worse outcomes. Data from early-phase studies of advanced non-small cell lung cancer (NSCLC) suggest encouraging antitumor activity with the combination of an HDAC inhibitor and either platinum-based chemotherapy or an EGFR inhibitor; however, toxicity is a limiting factor in the use of pan-HDAC inhibitors. Selective inhibition of HDAC6 may represent a potential therapeutic target and preclinical studies revealed immunomodulatory effects with HDAC6 inhibition, suggesting the potential for combination with immune checkpoint inhibitors. This phase Ib, multicenter, single-arm, open-label, dose-escalation study investigated the HDAC6 inhibitor ACY-241 (citarinostat) plus nivolumab in patients with previously treated advanced NSCLC who had not received a prior HDAC or immune checkpoint inhibitor.

METHODS

The orally administered ACY-241 dose was escalated (180, 360, or 480 mg once daily). Nivolumab was administered at 240 mg (day 15 of cycle 1, then every 2 weeks thereafter). The primary endpoint was to determine the maximum tolerated dose (MTD) of ACY-241 plus nivolumab. Secondary endpoints included safety, tolerability, and preliminary antitumor activity. Pharmacodynamics was an exploratory endpoint.

RESULTS

A total of 18 patients were enrolled, with 17 patients treated. No dose-limiting toxicities (DLTs) occurred with ACY-241 at 180 or 360 mg; 2 DLTs occurred at 480 mg. The MTD of ACY-241 was 360 mg. The most common grade ≥ 3 treatment-emergent adverse events were dyspnea (n = 3; 18%) and pneumonia (n = 3; 18%). At the 180-mg dose, 1 complete response and 2 partial responses (PRs) were observed. At the 360-mg dose, 3 PRs were observed; 1 patient achieved stable disease (SD) and 1 experienced progressive disease (PD). At the 480-mg dose, no responses were observed; 1 patient achieved SD and 3 experienced PD. Acetylation analyses revealed transient increases in histone and tubulin acetylation levels following treatment. An increase in infiltrating total CD3+ T cells was observed following treatment.

CONCLUSIONS

The study identified an MTD for ACY-241 plus nivolumab and the data suggest that the combination may be feasible in patients with advanced NSCLC. Responses were observed in patients with advanced NSCLC.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT02635061 (identifier, NCT02635061).

Clinical and pathophysiological characteristics of valproate-induced pleural effusion

INTRODUCTION

Valproic acid is a carboxylic acid derivative commonly prescribed for several types of seizure disorders or for acute manic episodes in patients with bipolar disorder. Several cases of valproate-induced pleural effusion have been reported, although the precise pathophysiological mechanism remains unknown.

OBJECTIVE

To describe the presentation of pleural effusion associated with valproate use and to categorize published case reports according to clinical, immunological, and pleural effusion cell type.

METHODS

PubMed/MEDLINE and Embase databases were systematically searched from January 1970 until November 2020 using the following search terms: "valproic acid" OR "valproate" OR "pleural fluid" OR "exudative effusion" OR "transudative effusion" OR "valproic lung adverse events". These searches yielded 171 references of which 135 articles were considered irrelevant, leaving 36 potentially relevant references which were carefully scrutinized. Twenty-eight cases of valproate-induced pleural effusion were identified after excluding two articles reporting five patients with lung parenchymal adverse reactions to treatment with valproic acid; two articles reporting three patients in whom the pleural effusion could not be attributed to valproic acid alone; one case discussing valproate therapy and fungal pleural effusion; and one describing a patient who suffered from severe cardiac failure. There were also two cases, in an abstract form, with pericardial and pleural effusion, but without any further informative details, and, thus, they were also excluded from this survey.

EXUDATIVE EOSINOPHILIC PLEURAL EFFUSION

This was the most common type of valproate-induced pleural effusion reported in 17 out of 28 cases (60.7%), with concurrent peripheral eosinophilia in ten. Acute hypersensitivity reaction, inflammation of the pleural cavity induced by the drug, drug toxicity, and damage to mesothelial cells due to oxidants, comprise the possible pivotal mechanisms.

EXUDATIVE LYMPHOCYTIC PLEURAL EFFUSION

This was reported in two cases, with concurrent pericardial effusion in one. Discontinuation of valproate led to resolution of the effusion, although the underlying pathophysiological mechanisms remain abstruse. Interestingly, a patient presented with recurrent pleural effusion characterized by transition from eosinophilic to lymphocytic predominance after readministration of valproate.

TRANSUDATIVE PLEURAL EFFUSION

Three out of 28 cases (10.7%) were characterized by neutrophilic transudative pleural effusion after long-term therapy with valproate, while concurrent pericardial effusion was also noted in two.

VALPROATE-INDUCED LUPUS ERYTHEMATOSUS WITH PLEURAL EFFUSION

Five patients receiving valproate therapy (17.9% out of the 28 cases) developed drug-induced lupus erythematosus with concurrent pleural effusion that was eosinophilic in three. All patients had positive antinuclear antibodies; anti-histone antibodies were positive in two.

CONCLUSIONS

Valproate-induced pleural effusion is rare, but patients receiving treatment with valproic acid who develop respiratory symptoms should be examined for valproate-induced pleural effusion.

Dissecting Histone Deacetylase 3 in Multiple Disease Conditions: Selective Inhibition as a Promising Therapeutic Strategy

The acetylation of histone and non-histone proteins has been implicated in several disease states. Modulation of such epigenetic modifications has therefore made histone deacetylases (HDACs) important drug targets. HDAC3, among various class I HDACs, has been signified as a potentially validated target in multiple diseases, namely, cancer, neurodegenerative diseases, diabetes, obesity, cardiovascular disorders, autoimmune diseases, inflammatory diseases, parasitic infections, and HIV. However, only a handful of HDAC3-selective inhibitors have been reported in spite of continuous efforts in design and development of HDAC3-selective inhibitors. In this Perspective, the roles of HDAC3 in various diseases as well as numerous potent and HDAC3-selective inhibitors have been discussed in detail. It will surely open up a new vista in the discovery of newer, more effective, and more selective HDAC3 inhibitors.

Genome-Wide Histone H3K27 Acetylation Profiling Identified Genes Correlated With Prognosis in Papillary Thyroid Carcinoma

Thyroid carcinoma (TC) is the most common endocrine malignancy, and papillary TC (PTC) is the most frequent subtype of TC, accounting for 85–90% of all the cases. Aberrant histone acetylation contributes to carcinogenesis by inducing the dysregulation of certain cancer-related genes. However, the histone acetylation landscape in PTC remains elusive. Here, we interrogated the epigenomes of PTC and benign thyroid nodule (BTN) tissues by applying H3K27ac chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) along with RNA-sequencing. By comparing the epigenomic features between PTC and BTN, we detected changes in H3K27ac levels at active regulatory regions, identified PTC-specific super-enhancer-associated genes involving immune-response and cancer-related pathways, and uncovered several genes that associated with disease-free survival of PTC. In summary, our data provided a genome-wide landscape of histone modification in PTC and demonstrated the role of enhancers in transcriptional regulations associated with prognosis of PTC.

Thiazolidinedione "Magic Bullets" Simultaneously Targeting PPARγ and HDACs: Design, Synthesis, and Investigations of their In Vitro and In Vivo Antitumor Effects

Monotargeting anticancer agents suffer from resistance and target nonspecificity concerns, which can be tackled with a multitargeting approach. The combined treatment with HDAC inhibitors and PPARγ agonists has displayed potential antitumor effects. Based on these observations, this work involves design and synthesis of molecules that can simultaneously target PPARγ and HDAC. Several out of 25 compounds inhibited HDAC4, and six compounds acted as dual-targeting agents. Compound 7i was the most potent, with activity toward PPARγ EC50 = 0.245 μM and HDAC4 IC50 = 1.1 μM. Additionally, compounds 7c and 7i were cytotoxic to CCRF-CEM cells (CC50 = 2.8 and 9.6 μM, respectively), induced apoptosis, and caused DNA fragmentation. Furthermore, compound 7c modulated the expression of c-Myc, cleaved caspase-3, and caused in vivo tumor regression in CCRF-CEM tumor xenografts. Thus, this study provides a basis for the rational design of dual/multitargeting agents that could be developed further as anticancer therapeutics.

Epigenetic modulation and understanding of HDAC inhibitors in cancer therapy

The role of genetic and epigenetic factors in tumor initiation and progression is well documented. Histone deacetylases (HDACs), histone methyl transferases (HMTs), and DNA methyl transferases. (DNMTs) are the main proteins that are involved in regulating the chromatin conformation. Among these, histone deacetylases (HDAC) deacetylate the histone and induce gene repression thereby leading to cancer. In contrast, histone acetyl transferases (HATs) that include GCN5, p300/CBP, PCAF, Tip 60 acetylate the histones. HDAC inhibitors are potent drug molecules that can induce acetylation of histones at lysine residues and induce open chromatin conformation at tumor suppressor gene loci and thus resulting in tumor suppression. The key processes regulated by HDAC inhibitors include cell-cycle arrest, chemo-sensitization, apoptosis induction, upregulation of tumor suppressors. Even though FDA approved drugs are confined mainly to haematological malignancies, the research on HDAC inhibitors in glioblastoma multiforme and triple negative breast cancer (TNBC) are providing positive results. Thus, several combinations of HDAC inhibitors along with DNA methyl transferase inhibitors and histone methyl transferase inhibitors are in clinical trials. This review focuses on how HDAC inhibitors regulate the expression of coding and non-coding genes with specific emphasis on their anti-cancer potential.

The Clinical Spectrum of Resistance to Thyroid Hormone Alpha in Children and Adults

Resistance to thyroid hormone alpha occurs due to pathogenic, heterozygous variants in THRA. The entity was first described in 2012 and to date only a small number of patients with varying severity have been reported. In this review, we summarize and interpret the heterogeneous clinical and laboratory features of all published cases, including ours. Many symptoms and findings are similar to those seen in primary hypothyroidism. However, thyroid-stimulating hormone levels are normal. Free triiodothyronine (T3) levels are in the upper half of normal range or frankly high and free thyroxine (T4) levels are low or in the lower half of normal range. Alterations in free T3 and free T4 may not be remarkable, particularly in adults, possibly contributing to underdiagnosis. In such patients, low reverse T3 levels, normo- or macrocytic anemia or, particularly in children, mildly elevated creatine kinase levels would warrant THRA sequencing. Treatment with L-thyroxine results in improvement of some clinical findings.

An immunochemistry-based screen for chemical inhibitors of DNA-protein interactions and its application to human CGGBP1

BACKGROUND

Inhibition of DNA-binding of proteins by small-molecule chemicals holds immense potential in manipulating the activities of DNA-binding proteins. Such a chemical inhibition of DNA-binding of proteins can be used to modulate processes such as replication, transcription, DNA repair and maintenance of epigenetic states. This prospect is currently challenged with the absence of robust and generic protocols to identify DNA-protein interactions. Additionally, much of the current approaches to designing inhibitors requires structural information of the target proteins.

METHODS

We have developed a simple dot blot and immunodetection-based assay to screen chemical libraries for inhibitors of DNA-protein interactions. The assay has been applied to a library of 1685 FDA-approved chemicals to discover inhibitors of CGGBP1, a multifunctional DNA-binding protein with no known structure. Additional in vitro and in cellulo assays have been performed to verify and supplement the findings of the screen.

RESULTS

Our primary screen has identified multiple inhibitors of direct or indirect interactions between CGGBP1 and genomic DNA. Of these, one inhibitor, Givinostat, was found to inhibit direct DNA-binding of CGGBP1 in the secondary screen using purified recombinant protein as the target. DNA and chromatin immunoprecipitation assays reinforced the findings of the screen that Givinostat inhibits CGGBP1-DNA binding.

CONCLUSIONS

The assay we have described successfully identifies verifiable inhibitors of DNA-binding of protein; in this example, the human CGGBP1. This assay is customizable for a wide range of targets for which primary antibodies are available. It works with different sources of the target protein, cell lysates or purified recombinant preparations and does not require special equipment, DNA modifications or protein structural data. This assay is scalable and highly adaptable with the potential to discover inhibitors of transcription factors with implications in cancer biology.

Recent Progress in Histone Deacetylase Inhibitors as Anticancer Agents

Histone Deacetylase (HDAC) inhibitors are a relatively new class of anti-cancer agents that play important roles in epigenetic or non-epigenetic regulation, inducing death, apoptosis, and cell cycle arrest in cancer cells. Recently, their use has been clinically validated in cancer patients resulting in the approval by the FDA of four HDAC inhibitors, vorinostat, romidepsin, belinostat and panobinostat, used for the treatment of cutaneous/peripheral T-cell lymphoma and multiple myeloma. Many more HDAC inhibitors are at different stages of clinical development for the treatment of hematological malignancies as well as solid tumors. Also, clinical trials of several HDAC inhibitors for use as anti-cancer drugs (alone or in combination with other anti-cancer therapeutics) are ongoing. In the intensifying efforts to discover new, hopefully, more therapeutically efficacious HDAC inhibitors, molecular modelingbased rational drug design has played an important role. In this review, we summarize four major structural classes of HDAC inhibitors (hydroxamic acid derivatives, aminobenzamide, cyclic peptide and short-chain fatty acids) that are in clinical trials and different computer modeling tools available for their structural modifications as a guide to discover additional HDAC inhibitors with greater therapeutic utility.

Targeting Epigenetic Modifications in Uveal Melanoma

Uveal melanoma (UM), the most common intraocular malignancy in adults, is a rare subset of melanoma. Despite effective primary therapy, around 50% of patients will develop the metastatic disease. Several clinical trials have been evaluated for patients with advanced UM, though outcomes remain dismal due to the lack of efficient therapies. Epigenetic dysregulation consisting of aberrant DNA methylation, histone modifications, and small non-coding RNA expression, silencing tumor suppressor genes, or activating oncogenes, have been shown to play a significant role in UM initiation and progression. Given that there is no evidence any approach improves results so far, adopting combination therapies, incorporating a new generation of epigenetic drugs targeting these alterations, may pave the way for novel promising therapeutic options. Furthermore, the fusion of effector enzymes with nuclease-deficient Cas9 (dCas9) in clustered regularly interspaced short palindromic repeats (CRISPR) associated protein 9 (Cas9) system equips a potent tool for locus-specific erasure or establishment of DNA methylation as well as histone modifications and, therefore, transcriptional regulation of specific genes. Both, CRISPR-dCas9 potential for driver epigenetic alterations discovery, and possibilities for their targeting in UM are highlighted in this review.

Dual targeting of GSK3B and HDACs reduces tumor growth and improves survival in an ovarian cancer mouse model

Objective.

To investigate the anti-tumor effect of a newly-developed dual inhibitor (APCS-540) of glycogen synthase kinase 3 beta (GSK3B) and histone deacetylases (HDACs) in ovarian cancer cells.

Methods.

The effects of APCS-540 on cancer cell proliferation, migration, invasion and cancer stemness were investigated in vitro in human (KURAMOCHI, OVCA420, OVSAHO) and mouse (BR-Luc, ID8, MOSE-HRas-Myc) ovarian cancer cells. Cisplatin-sensitive (A2780) and cisplatin-resistant (A2780cis) cell lines were used to evaluate APCS-540’s effect on chemoresistance. The immunocompetent syngeneic mouse model BR-Luc was used to test the effect of APCS-540 on ovarian cancer progression and survival.

Results.

APCS-540 showed significant anti-tumor effects in vitro in both human and mouse ovarian cancer cells. Importantly, APCS-540 demonstrated marked cytotoxicity against cisplatin-resistant cancer cells and reversed cisplatin-resistance when used in combination with platinum. APCS-540 significantly decreased cancer cell invasion. A significant 66% increase in survival was observed in mice treated with APCS-540 compared to control mice.

Conclusion.

Dual inhibition of GSK3B and HDACs via APCS-540 showed potent anti-tumor activity in vitro and in vivo, suggesting that APCS-540 may provide a novel treatment option for ovarian cancer, including the platinum-resistant disease.

Molecular docking-based virtual drug screening revealing an oxofluorenyl benzamide and a bromonaphthalene sulfonamido hydroxybenzoic acid as HDAC6 inhibitors with cytotoxicity against leukemia cells

HDAC6 is a crucial epigenetic modifier that plays a vital role in tumor progression and carcinogenesis due to its multiple biological functions. It is a unique member of class-II HDAC enzymes. It possesses two catalytic domains, which function independently of the overall enzyme activity. Up to date, there are only a few selective HDAC6 inhibitors with anti-cancer activity. In this study, 175,204 ligands obtained from the ZINC15 and OTAVAchemical databases were used for virtual drug screening against HDAC6. Molecular docking studies were performed for 100 selected compounds. Furthermore, the top 10 compounds obtained from docking were tested for their efficacy to inhibit the function of HDAC6. Five compounds (N-(9-oxo-9H-fluoren-3-yl)benzamide, 2-hydroxy-5-[(5-oxo-6-phenyl-4,5-dihydro-1,2,4-triazin-3-yl)amino]benzoic acid, 5-(4-bromonaphthalene-1-sulfonamido)-2-hydroxybenzoic acid, 2-(naphthalen-2-yl)-N-(1H-1,2,3,4-tetrazol-5-yl)cyclopropane-1-carboxamide, and 4-oxa-5,6 diazapentacyclo[10.7.1.0³,⁷.0⁸,²⁰.0¹⁴,¹⁹]icosa-1,3(7),5,8(20),9,11,14,16,18-nonaen-13-one) inhibited enzymatic activity by more than 50 % compared to DMSO as the control. Two candidates, (N-(9-oxo-9H-fluoren-3-yl)benzamide and 5-(4-bromonaphthalene-1-sulfonamido)-2-hydroxybenzoic acid), were identified with considerable cytotoxicity towards drug-sensitive CCRF-CEM and multidrug-resistant CEM/ADR5000 leukemia cells. Microscale thermophoresis revealed the binding of N-(9-oxo-9H-fluoren-3-yl)benzamide and 5-(4-bromonaphthalene-1-sulfonamido)-2-hydroxybenzoic acid to purified HDAC6 protein. Both compounds induced apoptosis in a dose-dependent manner as analyzed by flow cytometry. In conclusion, we demonstrate for the first time that these two compounds bind to HDAC6, inhibit its function, and exert cytotoxic activity by apoptosis induction.

Sodium valproate (VPA) interactions with DNA and histones

Valproic acid/sodium valproate (VPA) constitutes a widely prescribed drug for the treatment of seizure disorders and is a well-known epigenetic agent, inducing the acetylation of histones and affecting the methylation status of DNA and histones, with consequences on gene expression. Because this drug has been recently reported to exert affinity for histone H1, and to a minor degree for DNA, in this work, we investigated a possible interaction of sodium valproate with DNA and histones H1 and H3 using high-performance polarization microscopy and Fourier-transform infrared (FTIR) microspectroscopy. The preparations under examination consisted of hemispheres resulting from drop-casting samples containing VPA-DNA and VPA-histone mixtures. The results indicated that VPA may interact with DNA and histones, inducing changes in the textural superstructure and molecular order of the DNA possibly through van der Waals forces, and in histone H1 and H3 conformations, probably as a result of electrostatic binding between the drug and protein amino acid residues. These results contribute to a better understanding of the pharmacological potential of VPA. The precise sites and mechanisms involved in these interactions would certainly benefit from investigations provided by complementary methodologies.

Compensatory combination of romidepsin with gemcitabine and cisplatin to effectively and safely control urothelial carcinoma

BACKGROUND

Human urothelial carcinoma (UC) has a high tendency to recur and progress to life-threatening advanced diseases. Advanced therapeutic regimens are needed to control UC development and recurrence.

METHODS

We pursued in vitro and in vivo studies to understand the ability of a triple combination of gemcitabine, romidepsin, and cisplatin (Gem+Rom+Cis) to modulate signalling pathways, cell death, drug resistance, and tumour development.

RESULTS

Our studies verified the ability of Gem+Rom+Cis to synergistically induce apoptotic cell death and reduce drug resistance in various UC cells. The ERK pathway and reactive oxygen species (ROS) played essential roles in mediating Gem+Rom+Cis-induced caspase activation, DNA oxidation and damage, glutathione reduction, and unfolded protein response. Gem+Rom+Cis preferentially induced death and reduced drug resistance in oncogenic H-Ras-expressing UC vs. counterpart cells that was associated with transcriptomic profiles related to ROS, cell death, and drug resistance. Our studies also verified the efficacy and safety of the Gem plus Rom+Cis regimen in controlling UC cell-derived xenograft tumour development and resistance.

CONCLUSIONS

More than 80% of UCs are associated with aberrant Ras-ERK pathway. Thus the compensatory combination of Rom with Gem and Cis should be seriously considered as an advanced regimen for treating advanced UCs, especially Ras-ERK-activated UCs.

Targeting Mouse Double Minute 2: Current Concepts in DNA Damage Repair and Therapeutic Approaches in Cancer

Defects in DNA damage repair may cause genome instability and cancer development. The tumor suppressor gene p53 regulates cell cycle arrest to allow time for DNA repair. The oncoprotein mouse double minute 2 (MDM2) promotes cell survival, proliferation, invasion, and therapeutic resistance in many types of cancer. The major role of MDM2 is to inhibit p53 activity and promote its degradation. In this review, we describe the influence of MDM2 on genomic instability, the role of MDM2 on releasing p53 and binding DNA repair proteins to inhibit repair, and the regulation network of MDM2 including its transcriptional modifications, protein stability, and localization following DNA damage in genome integrity maintenance and in MDM2-p53 axis control. We also discuss p53-dependent and p53 independent oncogenic function of MDM2 and the outcomes of clinical trials that have been used with clinical inhibitors targeting p53-MDM2 to treat certain cancers.

Association of Valproic Acid Use, a Potent Histone Deacetylase Inhibitor, and Melanoma Risk

Histone deacetylase inhibitors, including valproic acid, selectively induce cellular differentiation and apoptosis in melanoma cells. No published pharmacoepidemiologic studies have explored the association between valproic acid use and melanoma risk. We conducted a retrospective cohort study of adult white Kaiser Permanente Northern California members (n = 2,213,845) from 1997 to 2012 to examine the association between valproic acid use and melanoma risk. Melanoma hazard ratios (HRs) and 95% CIs were estimated using Cox proportional hazards models, adjusted for age, sex, calendar year, and healthcare use. Melanoma incidence was lower among exposed individuals (64.0 exposed vs. 96.2 unexposed per 100,000 person-years, P < 0.001). Exposed individuals had a lower incident melanoma risk (HR = 0.64; 95% CI = 0.51-0.79) in unadjusted analysis, and the estimate was attenuated but significant in adjusted analysis (HR = 0.76, 95% CI = 0.61-0.94). Cumulative exposure based on the number of fills revealed a biologically implausible inverse dose-effect. Exposed individuals were more likely to present with local than regional or distant disease at diagnosis (80/82; 97.6% exposed vs. 12,940/13,971; 92.6% unexposed). Our findings suggest that valproic acid exposure may be associated with decreased melanoma risk and progression, but the cumulative exposure analyses suggest that the observation may be owing to residual confounding.

Alcoholic-Hepatitis, Links to Brain and Microbiome: Mechanisms, Clinical and Experimental Research

The following review article presents clinical and experimental features of alcohol-induced liver disease (ALD). Basic aspects of alcohol metabolism leading to the development of liver hepatotoxicity are discussed. ALD includes fatty liver, acute alcoholic hepatitis with or without liver failure, alcoholic steatohepatitis (ASH) leading to fibrosis and cirrhosis, and hepatocellular cancer (HCC). ALD is fully attributable to alcohol consumption. However, only 10-20% of heavy drinkers (persons consuming more than 40 g of ethanol/day) develop clinical ALD. Moreover, there is a link between behaviour and environmental factors that determine the amount of alcohol misuse and their liver disease. The range of clinical presentation varies from reversible alcoholic hepatic steatosis to cirrhosis, hepatic failure, and hepatocellular carcinoma. We aimed to (1) describe the clinico-pathology of ALD, (2) examine the role of immune responses in the development of alcoholic hepatitis (ASH), (3) propose diagnostic markers of ASH, (4) analyze the experimental models of ALD, (5) study the role of alcohol in changing the microbiota, and (6) articulate how findings in the liver and/or intestine influence the brain (and/or vice versa) on ASH; (7) identify pathways in alcohol-induced organ damage and (8) to target new innovative experimental concepts modeling the experimental approaches. The present review includes evidence recognizing the key toxic role of alcohol in ALD severity. Cytochrome p450 CYP2E1 activation may change the severity of ASH. The microbiota is a key element in immune responses, being an inducer of proinflammatory T helper 17 cells and regulatory T cells in the intestine. Alcohol consumption changes the intestinal microbiota and influences liver steatosis and liver inflammation. Knowing how to exploit the microbiome to modulate the immune system might lead to a new form of personalized medicine in ALF and ASH.

Selective Inhibition of HDAC1 by Macrocyclic Polypeptide for the Treatment of Glioblastoma: A Binding Mechanistic Analysis Based on Molecular Dynamics

Glioblastoma (GBM) is the most common and aggressive intracranial malignant brain tumor, and the abnormal expression of HDAC1 is closely correlated to the progression, recurrence and metastasis of GBM cells, making selective inhibition of HDAC1 a promising strategy for GBM treatments. Among all available selective HDAC1 inhibitors, the macrocyclic peptides have gained great attention due to their remarkable inhibitory selectivity on HDAC1. However, the binding mechanism underlying this selectivity is still elusive, which increases the difficulty of designing and synthesizing the macrocyclic peptide-based anti-GBM drug. Herein, multiple computational approaches were employed to explore the binding behaviors of a typical macrocyclic peptide FK228 in both HDAC1 and HDAC6. Starting from the docking conformations of FK228 in the binding pockets of HDAC1&6, relatively long MD simulation (500 ns) shown that the hydrophobic interaction and hydrogen bonding of E91 and D92 in the Loop2 of HDAC1 with the Cap had a certain traction effect on FK228, and the sub-pocket formed by Loop1 and Loop2 in HDAC1 could better accommodate the Cap group, which had a positive effect on maintaining the active conformation of FK228. While the weakening of the interactions between FK228 and the residues in the Loop2 of HDAC6 during the MD simulation led to the large deflection of FK228 in the binding site, which also resulted in the decrease in the interactions between the Linker region of FK228 and the previously identified key amino acids (H134, F143, H174, and F203). Therefore, the residues located in Loop1 and Loop2 contributed in maintaining the active conformation of FK228, which would provide valuable hints for the discovery and design of novel macrocyclic polypeptide HDAC inhibitors.

HDAC6, modulated by miR-206, promotes endometrial cancer progression through the PTEN/AKT/mTOR pathway

Endometrial cancer (EC) is the sixth most common cancer in women. Since early EC has a good prognosis, identifying methods for early diagnosis is valuable. Here, we aimed to study the role of HDAC6, which has been indicated important in many kinds of cancers, in EC diagnosis and therapy. First, the expression levels of HDAC6 in EC tissues and cells were measured by qRT-PCR and Western blotting, and through bioinformatics and dual luciferase assays, HDAC6 was found to be a direct target of miR-206. Then, CCK-8, colony formation, wound healing, and Transwell assays were performed; these results indicated that HDAC6 promoted EC cell proliferation, metastasis and invasion, while miR-206 produced the opposite effects. In addition, rescue assays verified that the effect of miR-206 could be reversed by HDAC6, and global gene expression analysis confirmed the relationship between miR-206 and HDAC6. Finally, we measured the levels of PTEN, p-AKT and p-mTOR and other key molecules and speculated that miR-206 might target HDAC6 to suppress EC progression via the PTEN/AKT/mTOR pathway. In conclusion, downregulation of miR-206 and upregulation of HDAC6 in EC may predict poor prognosis, and as the target gene of miR-206, HDAC achieves its carcinogenic effect through the PTEN/AKT/mTOR pathway.

Perineural Invasion Reprograms the Immune Microenvironment through Cholinergic Signaling in Pancreatic Ductal Adenocarcinoma

Perineural invasion is a common feature of pancreatic ductal adenocarcinoma (PDAC). Here, we investigated the effect of perineural invasion on the microenvironment and how this affects PDAC progression. Transcriptome expression profiles of PDAC tissues with different perineural invasion status were compared, and the intratumoral T-cell density and levels of neurotransmitters in these tissues were assessed. Perineural invasion was associated with impaired immune responses characterized by decreased CD8⁺ T and Th1 cells, and increased Th2 cells. Acetylcholine levels were elevated in severe perineural invasion. Acetylcholine impaired the ability of PDAC cells to recruit CD8⁺ T cells via HDAC1-mediated suppression of CCL5. Moreover, acetylcholine directly inhibited IFNγ production by CD8⁺ T cells in a dose-dependent manner and favored Th2 over Th1 differentiation. Furthermore, hyperactivation of cholinergic signaling enhanced tumor growth by suppressing the intratumoral T-cell response in an orthotopic PDAC model. Conversely, blocking perineural invasion with bilateral subdiaphragmatic vagotomy in tumor-bearing mice was associated with an increase in CD8⁺ T cells, an elevated Th1/Th2 ratio, and improved survival. In conclusion, perineural invasion-triggered cholinergic signaling favors tumor growth by promoting an immune-suppressive microenvironment characterized by impaired CD8⁺ T-cell infiltration and a reduced Th1/Th2 ratio. SIGNIFICANCE: These findings provide a promising therapeutic strategy to modulate the immunosuppressive microenvironment of pancreatic ductal adenocarcinoma with severe perineural invasion.

Targeting histone acetylation in pulmonary hypertension and right ventricular hypertrophy

Epigenetic mechanisms, including DNA methylation and histone post-translational modifications (PTMs), have been known to regulate chromatin structure and lineage-specific gene expression during cardiovascular development and disease. However, alterations in the landscape of histone PTMs and their contribution to the pathogenesis of incurable cardiovascular diseases such as pulmonary hypertension (PH) and associated right heart failure (RHF) remain largely unexplored. This review focusses on the studies in PH and RHF that investigated the gene families that write (histone acetyltransferases), read (bromodomain-containing proteins) or erase (histone deacetylases [HDACs] and sirtuins [SIRT]) acetyl moieties from the ε-amino group of lysine residues of histones and non-histone proteins. Analysis of cells and tissues isolated from the in vivo preclinical models of PH and human pulmonary arterial hypertension not only confirmed significant alterations in the expression levels of multiple HDACs, SIRT1, SIRT3 and BRD4 proteins but also demonstrated their strong association to proliferative, inflammatory and fibrotic phenotypes linked to the pathological vascular remodelling process. Due to the reversible nature of post-translational protein acetylation, the therapeutic efficacy of numerous small-molecule inhibitors (vorinostat, valproic acid, sodium butyrate, mocetinostat, entinostat, tubastatin A, apabetalone, JQ1 and resveratrol) have been evaluated in different preclinical models of cardiovascular disease, which revealed the promising therapeutic benefits of targeting histone acetylation pathways in the attenuation of cardiac hypertrophy, fibrosis, left heart dysfunction, PH and RHF. This review also emphasizes the need for deeper molecular insights into the contribution of epigenetic changes to PH pathogenesis and therapeutic evaluation of isoform-specific modulation in ex vivo and in vivo models of PH and RHF. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

Discovery of novel cyclin-dependent kinase (CDK) and histone deacetylase (HDAC) dual inhibitors with potent in vitro and in vivo anticancer activity

In the current study, we reported a series of novel 1-H-pyrazole-3-carboxamide-based inhibitors targeting histone deacetylase (HDAC) and cyclin-dependent kinase (CDK). The representative compounds N-(4-((2-aminophenyl)carbamoyl)benzyl)-4-(2,6-dichlorobenzamido)-1H-pyrazole-3-carboxamide (7c) and N-(4-(2-((2-aminophenyl)amino)-2-oxoethyl)phenyl)-4-(2,6-dichlorobenzamido)-1H-pyrazole-3-carboxamide (14a) with potent antiproliferative activities towards five solid cancer cell lines, showed excellent inhibitory activities against HDAC2 (IC₅₀ = 0.25 and 0.24 nM respectively) and CDK2 (IC₅₀ = 0.30 and 0.56 nM respectively). In addition, compounds 7c and 14a significantly inhibited the migration of A375 and H460 cells. Further studies revealed that compounds 7c and 14a could arrest cell cycle in G2/M phase and promote apoptosis in A375, HCT116, H460 and Hela cells, which was associated with increasing the intracellular reactive oxygen species (ROS) levels. More importantly, compound 7c possessed favorable pharmacokinetic properties with the intraperitoneal bioavailability of 63.6% in ICR mice, and potent in vivo antitumor efficacy in the HCT116 xenograft model. Our study demonstrated that compound 7c provides a promising strategy for the treatment of malignant tumors.

CAY10683 and imatinib have synergistic effects in overcoming imatinib resistance via HDAC2 inhibition in chronic myeloid leukemia

Imatinib (IM) is utilized for targeting the BCR-ABL fusion protein and as such, chronic myeloid leukemia (CML) is considered to be a curable disorder for which patients can achieve a long survival. However, 15-20% CML cases end up with IM resistance that will develop into the accelerated stage and eventually the blast crisis, thereby restricting the treatment choices and giving rise to a dismal survival rate. Histone deacetylases (HDACs) have been identified to modulate the oncogene as well as tumor suppressor gene activities, and they play crucial parts in tumorigenesis. It is found recently that IM combined with HDAC inhibitors (HDACi) can serve as a promising means of overcoming IM resistance in CML cases. Santacruzamate A (CAY10683) has been developed as one of the selective and powerful HDACi to resist HDAC2. Therefore, in this study, we aimed to examine whether CAY10683 combined with IM could serve as the candidate antitumor treatment for CML cases with IM resistance. The influences of CAY10683 combined with IM on the cell cycle arrest, apoptosis, and viability of CML cells with IM resistance were investigated, and it was discovered that the combined treatment exerted synergistic effects on managing the IM resistance. Moreover, further studies indicated that CAY10683 combined with IM mainly exerted synergistic effects through inhibiting HDAC2 in K562-R and LAMA84-R cells with IM resistance. Besides, the PI3K/Akt signal transduction pathway was found to mediate the HDAC2 regulation of CML cells with IM resistance. Eventually, it was also discovered, based on the xenograft mouse model, that the combined treatment dramatically suppressed CML proliferation in vivo. To sum up, findings in the current study indicate that CAY10683 combined with IM can be potentially used as the candidate treatment for CML with IM resistance.

Molecular Determinants of Cancer Therapy Resistance to HDAC Inhibitor-Induced Autophagy

Histone deacetylation inhibitors (HDACi) offer high potential for future cancer therapy as they can re-establish the expression of epigenetically silenced cell death programs. HDACi-induced autophagy offers the possibility to counteract the frequently present apoptosis-resistance as well as stress conditions of cancer cells. Opposed to the function of apoptosis and necrosis however, autophagy activated in cancer cells can engage in a tumor-suppressive or tumor-promoting manner depending on mostly unclarified factors. As a physiological adaption to apoptosis resistance in early phases of tumorigenesis, autophagy seems to resume a tumorsuppressive role that confines tumor necrosis and inflammation or even induces cell death in malignant cells. During later stages of tumor development, chemotherapeutic drug-induced autophagy seems to be reprogrammed by the cancer cell to prevent its elimination and support tumor progression. Consistently, HDACi-mediated activation of autophagy seems to exert a protective function that prevents the induction of apoptotic or necrotic cell death in cancer cells. Thus, resistance to HDACi-induced cell death is often encountered in various types of cancer as well. The current review highlights the different mechanisms of HDACi-elicited autophagy and corresponding possible molecular determinants of therapeutic resistance in cancer.

Sodium valproate and 5-aza-2'-deoxycytidine differentially modulate DNA demethylation in G1 phase-arrested and proliferative HeLa cells

Sodium valproate/valproic acid (VPA), a histone deacetylase inhibitor, and 5-aza-2-deoxycytidine (5-aza-CdR), a DNA methyltransferase 1 (DNMT1) inhibitor, induce DNA demethylation in several cell types. In HeLa cells, although VPA leads to decreased DNA 5-methylcytosine (5mC) levels, the demethylation pathway involved in this effect is not fully understood. We investigated this process using flow cytometry, ELISA, immunocytochemistry, Western blotting and RT-qPCR in G1 phase-arrested and proliferative HeLa cells compared to the presumably passive demethylation promoted by 5-aza-CdR. The results revealed that VPA acts predominantly on active DNA demethylation because it induced TET2 gene and protein overexpression, decreased 5mC abundance, and increased 5-hydroxy-methylcytosine (5hmC) abundance, in both G1-arrested and proliferative cells. However, because VPA caused decreased DNMT1 gene expression levels, it may also act on the passive demethylation pathway. 5-aza-CdR attenuated DNMT1 gene expression levels but increased TET2 and 5hmC abundance in replicating cells, although it did not affect the gene expression of TETs at any stage of the cell cycle. Therefore, 5-aza-CdR may also function in the active pathway. Because VPA reduces DNA methylation levels in non-replicating HeLa cells, it could be tested as a candidate for the therapeutic reversal of DNA methylation in cells in which cell division is arrested.

Fluvastatin potentiates anticancer activity of vorinostat in renal cancer cells

Drug repositioning is an emerging approach to developing novel cancer treatments. Vorinostat is a histone deacetylase inhibitor approved for cancer treatment, but it could attenuate its anticancer activity by activating the mTOR pathway. The HMG‐CoA reductase inhibitor fluvastatin reportedly activates the mTOR inhibitor AMP‐activated protein kinase (AMPK), and we thought that it would potentiate vorinostat's anticancer activity in renal cancer cells. The combination of vorinostat and fluvastatin induced robust apoptosis and inhibited renal cancer growth effectively both in vitro and in vivo. Vorinostat activated the mTOR pathway, as evidenced by the phosphorylation of ribosomal protein S6, and fluvastatin inhibited this phosphorylation by activating AMPK. Fluvastatin also enhanced vorinostat‐induced histone acetylation. Furthermore, the combination induced endoplasmic reticulum (ER) stress that was accompanied by aggresome formation. We also found that there was a positive feedback cycle among AMPK activation, histone acetylation, and ER stress induction. This is the first study to report the beneficial combined effect of vorinostat and fluvastatin in cancer cells.