Histone Deacetylase Inhibitor Research Articles

A novel histone deacetylase inhibitor Se-SAHA attenuates isoproterenol-induced heart failure via antioxidative stress and autophagy inhibition

Heart failure is associated with histone deacetylase (HDAC) regulation of gene expression, the inhibition of which is thought to be beneficial for heart failure therapy. Here, we explored the cardioprotective effects and underlying mechanism of a novel selenium-containing HDAC inhibitor, Se-SAHA, on isoproterenol (ISO)-induced heart failure. We found that pretreatment with Se-SAHA attenuated ISO-induced cardiac hypertrophy and fibrosis in neonatal rat ventricular myocytes (NRVMs). Se-SAHA significantly attenuated the generation of ISO-induced reactive oxygen species (ROS) and restored the expression levels of superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) in vitro. Furthermore, Se-SAHA pretreatment prevented the accumulation of autophagosomes. Se-SAHA reversed the high expression of HDAC1 and HDAC6 induced by ISO incubation. However, after the addition of the HDAC agonist, the effect of Se-SAHA on blocking autophagy was inhibited. Using ISO-induced mouse models, cardiac ventricular contractile dysfunction, hypertrophy, and fibrosis was reduced treated by Se-SAHA. In addition, Se-SAHA inhibited HDAC1 and HDAC6 overexpression in ISO-treated mice. Se-SAHA treatment significantly increased the activity of SOD2 and improved the ability to eliminate free radicals. Se-SAHA hindered the excessive levels of the microtubule-associated protein 1 light chain 3 (LC3)-II and Beclin-1 in heart failure mice. Collectively, our results indicate that Se-SAHA exerts cardio-protection against ISO-induced heart failure via antioxidative stress and autophagy inhibition.

Mechanistic Sequence of Histone Deacetylase Inhibitors and Radiation Treatment: An Overview.

Histone deacetylases inhibitors (HDACis) have shown promising therapeutic outcomes in haematological malignancies such as leukaemia, multiple myeloma, and lymphoma, with disappointing results in solid tumours when used as monotherapy. As a result, combination therapies either with radiation or other deoxyribonucleic acid (DNA) damaging agents have been suggested as ideal strategy to improve their efficacy in solid tumours. Numerous in vitro and in vivo studies have demonstrated that HDACis can sensitise malignant cells to both electromagnetic and particle types of radiation by inhibiting DNA damage repair. Although the radiosensitising ability of HDACis has been reported as early as the 1990s, the mechanisms of radiosensitisation are yet to be fully understood. This review brings forth the various protocols used to sequence the administration of radiation and HDACi treatments in the different studies. The possible contribution of these various protocols to the ambiguity that surrounds the mechanisms of radiosensitisation is also highlighted.

HDAC6 inhibitor promotes reactive oxygen species-meditated clearance of Staphylococcus aureus in macrophage.

Staphylococcus aureus (S. aureus) pneumonia has become an increasingly important public health problem. Recent evidence suggests that epigenetic modifications are critical in the host immune defence against pathogen infection. In this study, we found that S. aureus infection induces the expression of histone deacetylase 6 (HDAC6) in a dose-dependent manner. Furthermore, by using a S. aureus pneumonia mouse model, we showed that the HDAC6 inhibitor, tubastatin A, demonstrates a protective effect in S. aureus pneumonia, decreasing the mortality and destruction of lung architecture, reducing the bacterial burden in the lungs and inhibiting inflammatory responses. Mechanistic studies in primary bone marrow-derived macrophages demonstrated that the HDAC6 inhibitors, tubastatin A and tubacin, reduced the intracellular bacterial load by promoting bacterial clearance rather than regulating phagocytosis. Finally, N-acetyl-L- cysteine, a widely used reactive oxygen species (ROS) scavenger, antagonized ROS production and significantly inhibited tubastatin A-induced S. aureus clearance. These findings demonstrate that HDAC6 inhibitors promote the bactericidal activity of macrophages by inducing ROS, an important host factor for S. aureus clearance and production. Our study identified HDAC6 as a suitable epigenetic modification target for preventing S. aureus infection, and tubastatin A as a useful compound in treating S. aureus pneumonia.

HDAC Inhibition Increases CXCL12 Secretion to Recruit Natural Killer Cells in Peripheral T-cell Lymphoma.

Peripheral T-cell lymphoma (PTCL) is a heterogeneous and aggressive disease with a poor prognosis. Histone deacetylase (HDAC) inhibitors have shown inhibitory effects on PTCL. A better understanding of the therapeutic mechanism underlying the effects of HDAC inhibitors could help improve treatment strategies. Herein, we found that high expression of HDAC3 is associated with poor prognosis in PTCL. HDAC3 inhibition suppressed lymphoma growth in immunocompetent mice but not in immunodeficient mice. HDAC3 deletion delayed the progression of lymphoma, reduced the lymphoma burden in the thymus, spleen, and lymph nodes, and prolonged the survival of mice bearing N-methyl-N-nitrosourea-induced lymphoma. Furthermore, inhibiting HDAC3 promoted the infiltration and enhanced the function of natural killer (NK) cells. Mechanistically, HDAC3 mediated ATF3 deacetylation, enhancing its transcriptional inhibitory activity. Targeting HDAC3 enhanced CXCL12 secretion through an ATF3-dependent pathway to stimulate NK-cell recruitment and activation. Finally, HDAC3 suppression improved the response of PTCL to conventional chemotherapy. Collectively, this study provides insights into the mechanism by which HDAC3 regulates ATF3 activity and CXCL12 secretion, leading to immune infiltration and lymphoma suppression. Combining HDAC3 inhibitors with chemotherapy may be a promising strategy for treating PTCL. Significance: Targeting HDAC3 suppresses progression of T-cell lymphoma by activating ATF3 to induce secretion of CXCL12 and promote infiltration of NK cells, providing an immunostimulatory approach for treating T-cell lymphoma patients.

Histone deacetylase 6as a novel promising target to treat cardiovascular disease.

Histone deacetylase 6 (HDAC6) belongs to a class of epigenetic targets that have been found to be a key protein in the association between tumors and cardiovascular disease. Recent studies have focused on the crucial role of HDAC6 in regulating cardiovascular diseases such as atherosclerosis, myocardial infarction, myocardial hypertrophy, myocardial fibrosis, hypertension, pulmonary hypertension, and arrhythmia. Here, we review the association between HDAC6 and cardiovascular disease, the research progress of HDAC6 inhibitors in the treatment of cardiovascular disease, and discuss the feasibility of combining HDAC6 inhibitors with other therapeutic agents to treat cardiovascular disease.

Decrypting the molecular basis of cellular drug phenotypes by dose-resolved expression proteomics.

Proteomics is making important contributions to drug discovery, from target deconvolution to mechanism of action (MoA) elucidation and the identification of biomarkers of drug response. Here we introduce decryptE, a proteome-wide approach that measures the full dose-response characteristics of drug-induced protein expression changes that informs cellular drug MoA. Assaying 144 clinical drugs and research compounds against 8,000 proteins resulted in more than 1 million dose-response curves that can be interactively explored online in ProteomicsDB and a custom-built Shiny App. Analysis of the collective data provided molecular explanations for known phenotypic drug effects and uncovered new aspects of the MoA of human medicines. We found that histone deacetylase inhibitors potently and strongly down-regulated the T cell receptor complex resulting in impaired human T cell activation in vitro and ex vivo. This offers a rational explanation for the efficacy of histone deacetylase inhibitors in certain lymphomas and autoimmune diseases and explains their poor performance in treating solid tumors.

Histone Deacetylase Inhibitors Restore the Odontogenic Differentiation Potential of Dental Pulp Stem Cells under Hyperglycemic Conditions.

Complications arising from diabetes can result in stem cell dysfunction, impairing their ability to undergo differentiation into various cellular lineages. The present study evaluated the effect of histone deacetylase inhibitors, Valproic acid and Trichostatin A, on the odontogenic differentiation potential of dental pulp stem cells under hyperglycemic conditions. Streptozotocin (STZ) induced diabetes mellitus in 12 male Wistar rats. Dental parameters were examined using micro-computed tomography. The odontogenic potential of human pulp stem cells exposed to 30 mM glucose was assessed through alkaline phosphatase assays, examination of gene expression for dentin matrix protein 1 and dentin sialoprotein using real-time PCR, and alizarin red staining for calcium deposition. Along with reduced dentin thickness and root length in diabetic rats, the results revealed a significant increase in histone deacetylase 3 and 2 gene expressions in isolated diabetic pulp tissues compared to the control groups. The gene expression of odontogenic-related markers and alkaline phosphatase activity in human cultured pulp stem cells under hyperglycemic conditions significantly decreased. Adding Valproic acid and Trichostatin A restored the odontogenic differentiation markers, including calcium deposition, gene expression of dentin sialophosphoprotein, dentin matrix protein 1, and alkaline phosphatase activity. The data suggests that hyperglycemic conditions negatively impact the odontogenic potential of pulp mesenchymal stem cells. However, histone deacetylase inhibitors improve the impaired odontogenic differentiation capacity. This study implies that histone deacetylases may represent a potential therapeutic target for enhancing the regenerative mineralization of pulp cells in diabetic patients.

KiSS-1 Modulation by Epigenetic Agents Improves the Cisplatin Sensitivity of Lung Cancer Cells.

Epigenetic alterations my play a role in the aggressive behavior of Non-Small Cell Lung Cancer (NSCLC). Treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA, vorinostat) has been reported to interfere with the proliferative and invasive potential of NSCLC cells. In addition, the DNA methyltransferase inhibitor azacytidine (AZA, vidaza) can modulate the levels of the metastasis suppressor KiSS-1. Thus, since cisplatin is still clinically available for NSCLC therapy, the aim of this study was to evaluate drug combinations between cisplatin and SAHA as well as AZA using cisplatin-sensitive H460 and -resistant H460/Pt NSCLC cells in relation to KiSS-1 modulation. An analysis of drug interaction according to the Combination-Index values indicated a more marked synergistic effect when the exposure to SAHA or AZA preceded cisplatin treatment with respect to a simultaneous schedule. A modulation of proteins involved in apoptosis (p53, Bax) was found in both sensitive and resistant cells, and compared to the treatment with epigenetic agents alone, the combination of cisplatin and SAHA or AZA increased apoptosis induction. The epigenetic treatments, both as single agents and in combination, increased the release of KiSS-1. Finally, the exposure of cisplatin-sensitive and -resistant cells to the kisspeptin KP10 enhanced cisplatin induced cell death. The efficacy of the combination of SAHA and cisplatin was tested in vivo after subcutaneous inoculum of parental and resistant cells in immunodeficient mice. A significant tumor volume inhibition was found when mice bearing advanced tumors were treated with the combination of SAHA and cisplatin according to the best schedule identified in cellular studies. These results, together with the available literature, support that epigenetic drugs are amenable for the combination treatment of NSCLC, including patients bearing cisplatin-resistant tumors.

HDAC inhibitors activate lipid peroxidation and ferroptosis in gastric cancer

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

PSV-4 Exposure to prenatal tributyrin improved pre-weaning growth performance and reduced fat deposition in the muscle of market age pigs

Abstract Organic acids, including short chain fatty acids, medium chain fatty acids, and tricarboxylic acid, are used as alternatives to antibiotics for the purpose of growth promotion in livestock species. Butyric acid has been used extensively for its various functions in intestinal health and barrier function, as well as its actions as a histone deacetylase inhibitor. Many of the issues relating to using butyric acid as a feed supplement are overcome by utilizing tributyrin (TB), a butyrate prodrug. Dietary supplementation of TB to sows during gestation was able to improve pre-weaning litter performance. Sows (n = 52, 42 gestational days) were randomly assigned to either a control diet or control diet supplemented with 2% TB. All diets were made isocaloric with the addition of oil and wheat flour. Dietary treatments continued until 112 d of gestation. After farrowing, piglet growth performance was monitored. Once offspring reached 6 mo of age, 30 gilts from the most median performing litters were identified for tissue collection and evaluation of meat characteristics. Sows that received tributyrin during gestation tended to have greater total litter weights at birth (P < 0.1); however, average individual birthweights were not statistically different between control and TB litters. The TB piglets tended to be heavier at weaning (P < 0.1). Pre-weaning average daily gains were higher in piglets exposed to prenatal TB (P < 0.01). Body weights and hot carcass weights did not differ significantly in gilts at market age. There was, however, a trend of increased dressing percentage from TB treated offspring, accompanied by significantly reduced back fat at the 10th rib (P < 0.1 and P < 0.05 respectively). These data suggest that TB supplementation results in both temporary and permanent improvements to growth and development. This study provides further evidence that prenatal TB can have long term effects on muscle growth and meat quality. Further studies are needed to ultimately determine whether prenatal or postnatal supplementation is ideal for improving long-term growth performance.

Characterization of the dehydrogenase-reductase DHRS2 and its involvement in histone deacetylase inhibition in urological malignancies

BackgroundBeing implicated during tumor migration, invasion, clonogenicity, and proliferation, the nicotinamide adenine dinucleotide (NAD)/-phosphate (NADP)-dependent dehydrogenase/reductase member 2 (DHRS2) has been considered to be induced upon inhibition of histone deacetylases (HDACi). In this study, we evaluated the current knowledge on the underlying mechanisms of the (epi)genetic regulation of DHRS2, as well as its function during tumor progression. MethodsDHRS2 expression was evaluated on mRNA- and protein-level upon treatment with HDACi by means of qRT-PCR and western blot analyses, respectively. Re-analysis of RNA-sequencing data gained insight into expression of specific DHRS2 isoforms, while re-analysis of ATAC-sequencing data shed light on the chromatin accessibility at the DHRS2 locus. Further examination of the energy and lipid metabolism of HDACi-treated urologic tumor cells was performed using liquid chromatography-mass spectrometry. ResultsEnhanced DHRS2 expression levels upon HDACi treatment were directly linked to an enhanced chromatin accessibility at the DHRS2 locus. Particularly the DHRS2 ENST00000250383.11 protein-coding isoform was increased upon HDACi treatment. Application of the HDACi quisinostat only mildly influenced the energy metabolism of urologic tumor cells, though, the analysis of the lipid metabolism showed diminished sphingosine levels, as well as decreased S1P levels. Also the ratios of S1P/sphingosine and S1P/ceramides were reduced in all four quisinostat-treated urologic tumor cells. ConclusionsWith the emphasis on urologic malignancies (testicular germ cell tumors, urothelial, prostate, and renal cell carcinoma), this study concluded that elevated DHRS2 levels are indicative of a successful HDACi treatment and, thereby offering a novel putative predictive biomarker.

Abstract PO2-06-08: Suppression of GATA2/3-FOXA1-HER3 Axis by Histone Deacetylase (HDAC) Inhibitors shows Antitumor Activity in Basal-like Breast Cancer

Abstract Introduction: Basal-like breast cancer (BLBC) represents an aggressive subtype of triple-negative breast cancer (TNBC) that exhibits a high risk of recurrence and resistance to treatment. Histone deacetylase (HDAC) inhibitors (HDACis), including panobinostat and romidepsin, have obtained approval for the treatment of hematopoietic malignancies and demonstrated effectiveness in TNBC cells. We recently found that panobinostat and romidepsin potently induced TNBC cell growth inhibition and apoptosis via downregulation of HER3 through suppression of forkhead box protein A1 (FOXA1), a pioneering transcription factor. Nonetheless, the underlying mechanism through which HDACis suppress FOXA1, thereby inhibiting HER3 expression and its downstream signaling in FOXA1/HER3 co-expressing TNBC remains elusive. Methods: Colony formation, MTS, and LIVE/DEAD cell staining assays were used to detect cell viability. Apoptosis was detected by flow cytometry assays. QRT-PCR, western blots, and immunohistochemistry were performed to determine the expression and activation of genes and/or proteins. Co-immunoprecipitation was performed to assess the interaction between proteins. Lentivirus vectors containing cDNA or shRNAs were used to overexpress or knockdown gene expression. Chromatin immunoprecipitation-quantitative PCR and dual luciferase reporter assays were performed to elucidate the regulatory role of gene transcription. Results: Elevated expression of FOXA1 was observed in BLBC specimens and cell lines tested. FOXA1 was co-expressed with HER3 and transcriptionally activated the HER3 expression in BLBC cells. HER3 formed heterodimers with epidermal growth factor receptor (EGFR), activating downstream signaling pathways in BLBC cells. Treatment with panobinostat and romidepsin resulted in growth inhibition and apoptosis in BLBC cells by downregulating FOXA1 expression and inhibiting HER3 signaling. Notably, the combination of HDACis with an EGFR inhibitor (gefitinib) or an anti-HER3 antibody synergistically enhanced the anti-survival effects on BLBC cells. Additionally, gene expression profiling datasets revealed a significant positive correlation between FOXA1 expression and the transcription factors GATA-Binding Protein 2/3 (GATA2/3). Patients with high GATA2/3-FOXA1 expression exhibited worse Relapse-Free Survival (RFS) compared to those with low expressions in BLBC via Kaplan-Meier analysis. Further investigations showed that GATA2/3 directly activated FOXA1 transcription by binding to its promoter. Moreover, ectopic expression of GATA2/3 not only restored FOXA1 expression downregulated by HDACis but also attenuated the anti-survival effects of HDACis on BLBC cells. Conclusion: HDACis exhibit potent inhibitory effects on BLBC cells via downregulation of GATA2/3-mediated repression of FOXA1 gene transcription, which in turn suppresses HER3 expression and signaling. Our findings indicate that epigenetic targeting of the GATA2/3-FOXA1-HER3 axis may be an effective therapeutic strategy for the eradication of BLBC tumors. Keywords: FOXA1, GATA2/3, HER3, HDAC inhibitors, Basal-like breast cancer Citation Format: Bolin Liu, Congcong Tan, Hui Lyu. Suppression of GATA2/3-FOXA1-HER3 Axis by Histone Deacetylase (HDAC) Inhibitors shows Antitumor Activity in Basal-like Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-06-08.

Abstract PO1-19-04: Dalpiciclib and tucidinostat in patients with HR+/HER2- advanced breast cancer and resistance to CDK4/6 inhibitors: A phase Ib trial

Abstract Background: Hormone receptor (HR)-positive/epidermal growth factor receptor 2 (HER2)-negative breast cancer accounts for approximately 70% of all breast cancers and is associated with a better prognosis. Estrogen plays an important role in the growth of HR-positive breast cancer, thus patients with this type of tumor are sensitive to hormone inhibitors. However, a quarter of patients will inevitably relapse. Several large clinical trials have demonstrated that the combination of CDK4/6 inhibitors and endocrine therapy (ET) as first or second-line therapy could improve the progression-free survival (PFS) and overall survival for patients with breast cancer. In China, dalpiciclib (a CDK4/6 inhibitor) in combination with fulvestrant has been approved for patients with recurrent or metastatic HR-positive/HER2-negative breast cancer who have failed ET. Moreover, the combination of dalpiciclib and aromatase inhibitors (AI) as an initial treatment for patients with locally advanced or metastatic HR-positive/HER2-negative breast cancer has also been accepted. However, the standard treatment for patients who have failed CDK4/6 inhibitors has not been established. Histone deacetylase (HDAC) inhibitors cause alterations in gene expression in many signaling pathways associated with oncogenesis, leading to the arrest of tumor cell growth and differentiation, as well as promoting tumor apoptosis. Tucidinostat (an HDAC inhibitor) plus AI has been approved for the treatment of locally advanced HR-positive/HER2-negative postmenopausal breast cancer patients who have failed ET. Theoretically, synergistic effects may occur when HDAC inhibitors are combined with CDK4/6 inhibitors. Currently, the clinical data on combination therapy with CDK4/6 inhibitors and HDAC inhibitors have not been reported. Herein, our study aims to explore the efficacy and safety of dalpiciclib and tucidinostat in patients with late-stage HR+/HER2- breast cancer who have failed CDK4/6 inhibitors. Trial Design: The present study is a single-arm, open-label, phase I, dose escalation clinical trial (NCT 05586841). Patients were assigned to four groups to receive either dalpiciclib 125mg/d and tucidinostat 25mg/BIW (group A) or dalpiciclib 125mg/d and tucidinostat 20mg/BIW (group B) or dalpiciclib 100 mg/d and tucidinostat 25mg/BIW (group C) or dalpiciclib 100 mg/d and tucidinostat 20mg/BIW (group D). The Bayesian Optimal Interval (BOIN) design was performed to determine dose-escalation and de-escalation to find the maximum tolerated dose (MTD) of dalpiciclib plus tucidinostat. Key Eligibility Criteria: The study is enrolling female patients who are older than 18 years, with HR-positive/HER2-negative locally recurrent or metastatic breast cancer (MBC), with Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 2. Before entering this trial, all patients must have received ≤1 previous line of chemotherapy for recurrent or MBC, and have failed CDK4/6 inhibitor therapy. Aims: The BOIN design is employed to explore the optimal dose combination of dalpiciclib and tucidinostat and determine recommended doses for a phase II dose expansion clinical trial, based on prespecified dose-limiting toxicity (DLT). Statistical Methods: Safety will be evaluated in the safety set including all patients who received at least one dose of study treatment and underwent at least one safety assessment. Efficacy will be assessed in the full analysis set, defined as all patients who received at least one dose of study treatment. Present and Planned Accrual: Up to 30 participants were planned to be enrolled in the present study. The first participant was enrolled on 18 January 2023. The recruitment is ongoing. Citation Format: Tao Wang, Jinmei Zhou, Xuexue Wu, Zefei Jiang. Dalpiciclib and tucidinostat in patients with HR+/HER2- advanced breast cancer and resistance to CDK4/6 inhibitors: A phase Ib trial [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-19-04.

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

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

Design, synthesis and neuroprotective biological evaluation of novel HDAC6 inhibitors incorporating benzothiadiazinyl systems as cap groups.

Histone deacetylase 6 (HDAC6), as the key regulatory enzyme, plays an important role in the development of the nervous system. More and more studies indicate that HDAC6 has become a promising therapeutic target for CNS diseases. Herein we designed and synthesized a series of novel HDAC6 inhibitors with benzothiadiazinyl systems as cap groups and evaluated their activity invitro and invivo. Among them, compound 3 exhibited superior selective inhibitory activity against HDAC6 (IC50 = 5.1 nM, about 30-fold selectivity over HDAC1). The results of docking showed that compound 3 can interact well with the key amino acid residues of HDAC6. Compound 3 showed lower cytotoxicity (20 μM to SH-SY5Y cells, inhibition rate = 25.75%) and better neuroprotective activity against L-glutamate-induced SH-SY5Y cell injury model invitro. Meanwhile, compound 3 exhibited weak cardiotoxicity (10 μM hERG inhibition rate = 17.35%) and possess good druggability properties. Especially, compound 3 could significantly reduce cerebral infarction from 49.87% to 32.18%, and similar with butylphthalide in MCAO model, indicating potential clinical application prospects for alleviating ischemic stroke-induced brain infarction.

Exposure to Prenatal Tributyrin Improved Pre-Weaning Growth Performance and Reduced Fat Deposition in the Muscle of Market Age Pigs

Organic acids, including short chain fatty acids, medium chain fatty acids, and tricarboxylic acid, are used as alternatives to antibiotics for the purpose of growth promotion in livestock species. Butyric acid has been used extensively for its various functions in intestinal health and barrier function, as well as its actions as a histone deacetylase inhibitor. Many of the issues related to using butyric acid as a feed supplement are overcome by utilizing tributyrin (TB), a butyrate prodrug. Dietary supplementation of TB to sows during gestation was able to improve pre-weaning litter performance. Sows (n=52, 42 gestational days) were randomly assigned to either a control diet or control diet supplemented with 2% TB. All diets were made isocaloric with the addition of oil and wheat flour. Dietary treatments continued until 112 days of gestation. After farrowing, piglet growth performance was monitored. Once offspring reached 6 months of age, 30 gilts from the most median performing litters were identified for tissue collection and evaluation of meat characteristics. Sows that received tributyrin during gestation tended to have higher total litter weights at birth (P value < 0.1), however, average individual birthweights were not statistically different between control and TB litters. TB piglets tended to be heavier at weaning (P value < 0.1). Pre-weaning average daily gains were higher in piglets exposed to prenatal TB (P value < 0.01). Live weights and hot carcass weights did not differ significantly in gilts at market age. There was, however, a trend of increased dressing percentage from TB treated offspring, accompanied by significantly reduced back fat at the 10th rib (P value < 0.1 and P value < 0.05 respectively). This data suggests that TB supplementation results in both temporary and permanent improvements to growth and development. This study provides further evidence that prenatal TB can have long term effects on muscle growth and meat quality. Further studies are needed to ultimately determine whether prenatal or postnatal supplementation is ideal for improving long-term growth performance. USDA Grant Funded. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Histone Deacetylase Inhibition Increases Glycerol Uptake in Normal and Hyperglycemic Conditions in Human Corneal Epithelial Cells

Delayed corneal wound healing, such as is seen in diabetes, can lead to visual impairment. Diabetes afflicts over 30 million Americans and leads to multiple comorbidities. Histone deacetylase (HDAC) expression and activity are increased in diabetes in correlation with an upregulation of inflammatory molecules and reactive oxygen species (ROS). HDACs have been previously found to suppress the expression of the glycerol channel aquaporin-3 (AQP3) in epithelial cells of the skin, the epidermal keratinocytes. Global deletion of AQP3 in mice has been found to delay corneal wound healing. We hypothesized that hyperglycemic conditions would decrease AQP3 levels and function while increasing the expression of HDAC(s), ROS scavenger proteins, and inflammatory mediators in human corneal epithelial cells (HCECs). HCECs were incubated for 48-hours in high glucose (25.5 mM) or normal glucose (~5.0 mM osmotically matched by mannitol) conditions. Under hyperglycemic conditions, the mRNA expression of interleukin-1α and -1β was significantly elevated, providing evidence for a pro-inflammatory effect of acute hyperglycemia in HCECs. Under these conditions, there was a significant increase in the mRNA expression of the ROS scavenger genes, superoxide dismutase-1 and -2 and peroxiredoxin-3 and -6, suggesting a compensatory response to an increase in ROS generation. Under acute hyperglycemic conditions, HDAC3 and HDAC8 mRNA expression also tended to increase while HDAC1 and HDAC2 mRNA levels remained unchanged. Although an upregulation of HDAC expression would be predicted to decrease AQP3 expression, AQP3 mRNA and protein expression levels were also unchanged. In addition, acute hyperglycemia (48 hours) did not alter glycerol transport into the HCECs, as measured by their uptake of radiolabeled [14C]-glycerol. However, HDAC inhibition using the broad-spectrum inhibitor SAHA for 24 hours increased [14C]-glycerol uptake under both normoglycemic and hyperglycemic conditions, suggesting that HDAC activity plays a role in AQP3 function. Overall, acute hyperglycemic conditions were pro-inflammatory and led to increased expression of ROS-scavenging genes; hyperglycemia also tended to upregulate HDAC expression, although without affecting AQP3 expression. On the other hand, HDAC inhibition increased glycerol uptake, an indicator of AQP3 function, suggesting an ability of HDAC activity to regulate AQP3 glycerol transport activity. National Institutes of Health/National Eye Institute award #R01EY030576 (to MW and WBB) VA Merit #BX005055 (to WBB). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

New synergistic combination therapy approaches with HDAC inhibitor quisinostat, cisplatin or PARP inhibitor talazoparib for urothelial carcinoma.

Urothelial carcinoma (UC) urgently requires new therapeutic options. Histone deacetylases (HDAC) are frequently dysregulated in UC and constitute interesting targets for the development of alternative therapy options. Thus, we investigated the effect of the second generation HDAC inhibitor (HDACi) quisinostat in five UC cell lines (UCC) and two normal control cell lines in comparison to romidepsin, a well characterized HDACi which was previously shown to induce cell death and cell cycle arrest. In UCC, quisinostat led to cell cycle alterations, cell death induction and DNA damage, but was well tolerated by normal cells. Combinations of quisinostat with cisplatin or the PARP inhibitor talazoparib led to decrease in cell viability and significant synergistic effect in five UCCs and platinum-resistant sublines allowing dose reduction. Further analyses in UM-UC-3 and J82 at low dose ratio revealed that the mechanisms included cell cycle disturbance, apoptosis induction and DNA damage. These combinations appeared to be well tolerated in normal cells. In conclusion, our results suggest new promising combination regimes for treatment of UC, also in the cisplatin-resistant setting.

The different response of Brassica napus genotypes to microspore embryogenesis induced by heat shock and trichostatin A is not determined by changes in cell wall structure and composition but by different stress tolerance

AbstractDuring microspore embryogenesis, microspores are induced to develop into haploid embryos. In Brassica napus, microspore embryogenesis is induced by a heat shock (HS), which initially produces embryogenic structures with different cell wall architectures and compositions, and with different potentials to develop into embryos. The B. napus DH4079 and DH12075 genotypes have high and very low embryo yields, respectively. In DH12075, embryo yield is greatly increased by combining HS and the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). However, we show that HS + TSA inhibits embryogenesis in the highly embryogenic DH4079 line. To ascertain why TSA has such different effects in these lines, we treated DH4079 and DH12075 microspore cultures with TSA and compared the cell wall structure and composition of the different embryogenic structures in both lines, specifically the in situ levels and distribution of callose, cellulose, arabinogalactan proteins and high and low methyl‐esterified pectin. For both lines, HS + TSA led to the formation of cell walls unfavorable for embryogenesis progression, with reduced levels of arabinogalactan proteins, reduced cell adhesion of inner walls and altered pectin composition. Thus, TSA effects on cell walls cannot explain their different embryogenic response to TSA. We also applied TSA to DH4079 cultures at different times and concentrations before HS application, with no negative effects on embryogenic induction. These results indicate that DH4079 microspores are hypersensitive to combined TSA and HS treatments, and open up new hypotheses about the causes of such hypersensitivity.

Reduction of H3K9 methylation by G9a inhibitors improves the development of mouse SCNT embryos

Removal of somatic histone H3 lysine 9 trimethylation (H3K9me3) from the embryonic genome can improve the efficiency of mammalian cloning using somatic cell nuclear transfer (SCNT). However, this strategy involves the injection of histone demethylase mRNA into embryos, which is limiting because of its invasive and labor-consuming nature. Here, we report that treatment with an inhibitor of G9a (G9ai), the major histone methyltransferase that introduces H3K9me1/2 in mammals, greatly improved the development of mouse SCNT embryos. Intriguingly, G9ai caused an immediate reduction of H3K9me1/2, a secondary loss of H3K9me3 in SCNT embryos, and increased the birth rate of cloned pups about 5-fold (up to 3.9%). G9ai combined with the histone deacetylase inhibitor trichostatin A further improved this rate to 14.5%. Mechanistically, G9ai and TSA synergistically enhanced H3K9me3 demethylation and boosted zygotic genome activation. Thus, we established an easy, highly effective SCNT protocol that would enhance future cloning research and applications.