Targeting histone deacetylases in head and neck squamous cell carcinoma: molecular mechanisms and therapeutic targets.

The onerous health and economic burden associated with head and neck squamous cell carcinoma (HNSCC) is a global predicament. Despite the advent of novel surgical techniques and therapeutic protocols, there is an incessant need for efficacious diagnostic and therapeutic targets to monitor the invasion, metastasis and recurrence of HNSCC due to its substantial morbidity and mortality. The differential expression patterns of histone deacetylases (HDACs), a group of enzymes responsible for modifying histones and regulating gene expression, have been demonstrated in neoplastic tissues. However, there is limited knowledge regarding the role of HDACs in HNSCC. Consequently, this review aims to summarize the existing research findings and explore the potential association between HDACs and HNSCC, offering fresh perspectives on therapeutic approaches targeting HDACs that could potentially enhance the efficacy of HNSCC treatment. Additionally, the Cancer Genome Atlas (TCGA) dataset, CPTAC, HPA, OmicShare, GeneMANIA and STRING databases are utilized to provide supplementary evidence on the differential expression of HDACs, their prognostic significance and predicting functions in HNSCC patients.

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 in vitro and in vivo. 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 in vitro. 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.

Exploring the role of histone deacetylase inhibitors in cancer development and therapeutic potential.

The process of acetylation and deacetylation of histones within the nucleus operates within a dynamic equilibrium. Histone acetyltransferases (HATs) and histone deacetylases (HDACs) collaboratively and precisely regulate normal gene transcription and expression. Any disorder in the activity of HATs/HDACs can lead to uncontrolled gene expression, consequently resulting in tumorigenesis. Histone deacetylase inhibitors (HDACIs) have the capacity to block the cell cycle, thereby restraining tumor cell proliferation and tumor growth. Also, HDACIs exhibit a significant capability to diminish the expression of apoptosis protein inhibitors such as Bcl-2 and B-cell lymphoma-extra-large (Bcl-xL), while concurrently up-regulating pro-apoptotic proteins such as Bax, Bad, and Bim. Also, HDACIs demonstrate the ability to inhibit tumor cell angiogenesis. Representing a new category of targeted anti-cancer therapeutics, HDACIs possess the capability to restore the expression of tumor suppressor genes, induce apoptosis, and stimulate cell differentiation. Additionally, they exert anti-cancer effects through diverse pathways both in vivo and in vitro, thereby presenting promising prospects in tumor therapy. This review delves into the involvement of HDACs in cancer pathology and the therapeutic potential of HDACIs as emerging drugs in cancer treatment.

Valproic Acid Treatment after Traumatic Brain Injury in Mice Alleviates Neuronal Death and Inflammation in Association with Increased Plasma Lysophosphatidylcholines.

The histone deacetylase inhibitor (HDACi) valproic acid (VPA) has neuroprotective and anti-inflammatory effects in experimental traumatic brain injury (TBI), which have been partially attributed to the epigenetic disinhibition of the transcription repressor RE1-Silencing Transcription Factor/Neuron-Restrictive Silencer Factor (REST/NRSF). Additionally, VPA changes post-traumatic brain injury (TBI) brain metabolism to create a neuroprotective environment. To address the interconnection of neuroprotection, metabolism, inflammation and REST/NRSF after TBI, we subjected C57BL/6N mice to experimental TBI and intraperitoneal VPA administration or vehicle solution at 15 min, 1, 2, and 3 days post-injury (dpi). At 7 dpi, TBI-induced an up-regulation of REST/NRSF gene expression and HDACi function of VPA on histone H3 acetylation were confirmed. Neurological deficits, brain lesion size, blood-brain barrier permeability, or astrogliosis were not affected, and REST/NRSF target genes were only marginally influenced by VPA. However, VPA attenuated structural damage in the hippocampus, microgliosis and expression of the pro-inflammatory marker genes. Analyses of plasma lipidomic and polar metabolomic patterns revealed that VPA treatment increased lysophosphatidylcholines (LPCs), which were inversely associated with interleukin 1 beta (Il1b) and tumor necrosis factor (Tnf) gene expression in the brain. The results show that VPA has mild neuroprotective and anti-inflammatory effects likely originating from favorable systemic metabolic changes resulting in increased plasma LPCs that are known to be actively taken up by the brain and function as carriers for neuroprotective polyunsaturated fatty acids.

Histone deacetylase-3 regulates the expression of the amyloid precursor protein and its inhibition promotes neuroregenerative pathways in Alzheimer's disease models.

HDAC3 inhibition has been shown to improve memory and reduce amyloid-ß (Aß) in Alzheimer's disease (AD) models, but the underlying mechanisms are unclear. We investigated the molecular effects of HDAC3 inhibition on AD pathology, using in vitro and ex vivo models of AD, based on our finding that HDAC3 expression is increased in AD brains. For this purpose, N2a mouse neuroblastoma cells as well as organotypic brain cultures (OBCSs) of 5XFAD and wild-type mice were incubated with various concentrations of the HDAC3 selective inhibitor RGFP966 (0.1-10 µM) for 24 h. Treatment with RGFP966 or HDAC3 knockdown in N2a cells was associated with an increase on amyloid precursor protein (APP) and mRNA expressions, without alterations in Aß42 secretion. In vitro chromatin immunoprecipitation analysis revealed enriched HDAC3 binding at APP promoter regions. The increase in APP expression was also detected in OBCSs from 5XFAD mice incubated with 1 µM RGFP966, without changes in Aß. In addition, HDAC3 inhibition resulted in a reduction of activated Iba-1-positive microglia and astrocytes in 5XFAD slices, which was not observed in OBCSs from wild-type mice. mRNA sequencing analysis revealed that HDAC3 inhibition modulated neuronal regenerative pathways related to neurogenesis, differentiation, axonogenesis, and dendritic spine density in OBCSs. Our findings highlight the complexity and diversity of the effects of HDAC3 inhibition on AD models and suggest that HDAC3 may have multiple roles in the regulation of APP expression and processing, as well as in the modulation of neuroinflammatory and neuroprotective genes.

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.

Histone deacetylase as emerging pharmacological therapeutic target for neuropathic pain: From epigenetic to selective drugs.

BACKGROUND: Neuropathic pain remains a formidable challenge for modern medicine. The first-line pharmacological therapies exhibit limited efficacy and unfavorable side effect profiles, highlighting an unmet need for effective therapeutic medications. The past decades have witnessed an explosion in efforts to translate epigenetic concepts into pain therapy and shed light on epigenetics as a promising avenue for pain research. Recently, the aberrant activity of histone deacetylase (HDAC) has emerged as a key mechanism contributing to the development and maintenance of neuropathic pain. AIMS: In this review, we highlight the distinctive role of specific HDAC subtypes in a cell-specific manner in pain nociception, and outline the recent experimental evidence supporting the therapeutic potential of HDACi in neuropathic pain. METHODS: We have summarized studies of HDAC in neuropathic pain in Pubmed. RESULTS: HDACs, widely distributed in the neuronal and non-neuronal cells of the dorsal root ganglion and spinal cord, regulate gene expression by deacetylation of histone or non-histone proteins and involving in increased neuronal excitability and neuroinflammation, thus promoting peripheral and central sensitization. Importantly, pharmacological manipulation of aberrant acetylation using HDAC-targeted inhibitors (HDACi) has shown promising pain-relieving properties in various preclinical models of neuropathic pain. Yet, many of which exhibit low-specificity that may induce off-target toxicities, underscoring the necessity for the development of isoform-selective HDACi in pain management. CONCLUSIONS: Abnormally elevated HDACs promote neuronal excitability and neuroinflammation by epigenetically modulating pivotal gene expression in neuronal and immune cells, contributing to peripheral and central sensitization in the progression of neuropathic pain, and HDACi showed significant efficacy and great potential for alleviating neuropathic pain.

Tinostamustine (EDO-S101), an Alkylating Deacetylase Inhibitor, Enhances the Efficacy of Daratumumab in Multiple Myeloma by Upregulation of CD38 and NKG2D Ligands.

Multiple myeloma is a malignancy characterized by the accumulation of malignant plasma cells in bone marrow and the production of monoclonal immunoglobulin. A hallmark of cancer is the evasion of immune surveillance. Histone deacetylase inhibitors have been shown to promote the expression of silenced molecules and hold potential to increase the anti-MM efficacy of immunotherapy. The aim of the present work was to assess the potential effect of tinostamustine (EDO-S101), a first-in-class alkylating deacetylase inhibitor, in combination with daratumumab, an anti-CD38 monoclonal antibody (mAb), through different preclinical studies. Tinostamustine increases CD38 expression in myeloma cell lines, an effect that occurs in parallel with an increment in CD38 histone H3 acetylation levels. Also, the expression of MICA and MICB, ligands for the NK cell activating receptor NKG2D, augments after tinostamustine treatment in myeloma cell lines and primary myeloma cells. Pretreatment of myeloma cell lines with tinostamustine increased the sensitivity of these cells to daratumumab through its different cytotoxic mechanisms, and the combination of these two drugs showed a higher anti-myeloma effect than individual treatments in ex vivo cultures of myeloma patients' samples. In vivo data confirmed that tinostamustine pretreatment followed by daratumumab administration significantly delayed tumor growth and improved the survival of mice compared to individual treatments. In summary, our results suggest that tinostamustine could be a potential candidate to improve the efficacy of anti-CD38 mAbs.

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.

Preferential HDAC6 inhibitors derived from HPOB exhibit synergistic antileukemia activity in combination with decitabine.

Histone deacetylase 6 (HDAC6) is an emerging drug target to treat oncological and non-oncological conditions. Since highly selective HDAC6 inhibitors display limited anticancer activity when used as single agent, they usually require combination therapies with other chemotherapeutics. In this work, we synthesized a mini library of analogues of the preferential HDAC6 inhibitor HPOB in only two steps via an Ugi four-component reaction as the key step. Biochemical HDAC inhibition and cell viability assays led to the identification of 1g (highest antileukemic activity) and 2b (highest HDAC6 inhibition) as hit compounds. In subsequent combination screens, both 1g and especially 2b showed synergy with DNA methyltransferase inhibitor decitabine in acute myeloid leukemia (AML). Our findings highlight the potential of combining HDAC6 inhibitors with DNA methyltransferase inhibitors as a strategy to improve AML treatment outcomes.

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.

Molecular docking, synthesis, characteristics and preliminary cytotoxic study of new coumarin-sulfonamide derivatives as histone deacetylase inhibitors.

OBJECTIVE: Aim: To evaluate the cytotoxic activity of newly synthesized a series of novel HDAC inhibitors comprising sulfonamide as zinc binding group and Coumarin as cap groups. PATIENTS AND METHODS: Materials and Methods: The utilization of sulfonamide as zinc binding group and Coumarin as cap groups known to possess antitumor activity in the designed of new histone deacetylase inhibitors and using the docking and MTT assay to evaluate the compounds. RESULTS: Results: Four compounds have been synthesized and characterized successfully by ART-FTIR, NMR and ESI-Ms. The synthesized compound assessed for their cytotoxic activity against hepatoblastoma HepG2 (IC50, I=0.094, II=0.040, III=0.032, IV=0.046, SAHA=0.141) and human colon adenocarcinoma MCF-7 (IC50, I=0.135, II=0.050, III= 0.065, IV=0.059, SAHA=0.107). The binding mode to the active site of [HDAC6] were determined by docking study which give results that they might be good inhibitors for [HDAC6]. CONCLUSION: Conclusions: The synthesized compounds (I, II, III and IV) showed a comparable cytotoxic result with FDA approved drug (SAHA) toward HepG2 and MCF-7 cancer cell lines and their docking analysis provided a preliminary indication that they are viable [HDAC6] candidates.

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.

Neutrophil Elastase Degrades Histone Deacetylases and Sirtuin 1 in Primary Human Monocyte Derived Macrophages.

Neutrophil elastase (NE) is taken up by macrophages, retains intracellular protease activity, and induces a pro-inflammatory phenotype. However, the mechanism of NE-induced pro-inflammatory polarization of macrophages is not well understood. We hypothesized that intracellular NE degrades histone deacetylases (HDAC) and Sirtuins, disrupting the balance of lysine acetylation and deacetylation and resulting in nuclear to cytoplasmic translocation of a major alarmin, High Mobility Group Box 1 (HMGB1), a pro-inflammatory response in macrophages. Human blood monocytes were obtained from healthy donors or from subjects with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). Monocytes were differentiated into blood monocyte derived macrophages (BMDMs) in vitro. Human BMDMs were exposed to NE or control vehicle, and the abundance of HDACs and Sirtuins was determined by Western blotting of total cell lysates or nuclear extracts or determined by ELISA. HDAC, Sirtuin, and Histone acetyltransferase (HAT) activities were measured. NE degraded most HDACs and Sirtuin (Sirt)1, resulting in decreased HDAC and sirtuin activities, with minimal change in HAT activity. We then evaluated whether the NE-induced loss of Sirt activity or loss of HDAC activities would alter the cellular localization of HMGB1. NE treatment or treatment with Trichostatin A (TSA), a global HDAC inhibitor, both increased HMGB1 translocation from the nucleus to the cytoplasm, consistent with HMGB1 activation. NE significantly degraded Class I and II HDAC family members and Sirt 1, which shifted BMDMs to a pro-inflammatory phenotype.

Ketogenic Diet Alters the Epigenetic and Immune Landscape of Prostate Cancer to Overcome Resistance to Immune Checkpoint Blockade Therapy.

Resistance to immune checkpoint blockade (ICB) therapy represents a formidable clinical challenge limiting the efficacy of immunotherapy. In particular, prostate cancer poses a challenge for ICB therapy due to its immunosuppressive features. A ketogenic diet (KD) has been reported to enhance response to ICB therapy in some other cancer models. However, adverse effects associated with continuous KD were also observed, demanding better mechanistic understanding and optimized regimens for using KD as an immunotherapy sensitizer. In this study, we established a series of ICB-resistant prostate cancer cell lines and developed a highly effective strategy of combining anti-PD1 and anti-CTLA4 antibodies with histone deacetylase inhibitor (HDACi) vorinostat, a cyclic KD (CKD), or dietary supplementation of the ketone body ß-hydroxybutyrate (BHB), which is an endogenous HDACi. CKD and BHB supplementation each delayed prostate cancer tumor growth as monotherapy, and both BHB and adaptive immunity were required for the antitumor activity of CKD. Single-cell transcriptomic and proteomic profiling revealed that HDACi and ketogenesis enhanced ICB efficacy through both cancer cell-intrinsic mechanisms, including upregulation of MHC class I molecules, and -extrinsic mechanisms, such as CD8+ T-cell chemoattraction, M1/M2 macrophage rebalancing, monocyte differentiation toward antigen-presenting cells, and diminished neutrophil infiltration. Overall, these findings illuminate a potential clinical path of using HDACi and optimized KD regimens to enhance ICB therapy for prostate cancer. SIGNIFICANCE: Optimized cyclic ketogenic diet and 1,3-butanediol supplementation regimens enhance the efficacy of immune checkpoint blockade in prostate cancer through epigenetic and immune modulations, providing dietary interventions to sensitize tumors to immunotherapy.

Class I HDAC inhibitors enhance antitumor efficacy and persistence of CAR-T cells by activation of the Wnt pathway.

Epigenetic modification shapes differentiation trajectory and regulates the exhaustion state of chimeric antigen receptor T (CAR-T) cells. Limited efficacy induced by terminal exhaustion closely ties with intrinsic transcriptional regulation. However, the comprehensive regulatory mechanisms remain largely elusive. Here, we identify class I histone deacetylase inhibitors (HDACi) as boosters of CAR-T cell function by high-throughput screening of chromatin-modifying drugs, in which M344 and chidamide enhance memory maintenance and resistance to exhaustion of CAR-T cells that induce sustained antitumor efficacy both in vitro and in vivo. Mechanistically, HDACi decrease HDAC1 expression and enhance H3K27ac activity. Multi-omics analyses from RNA-seq, ATAC-seq, and H3K27ac CUT&Tag-seq show that HDACi upregulate expression of TCF4, LEF1, and CTNNB1, which subsequently activate the canonical Wnt/ß-catenin pathway. Collectively, our findings elucidate the functional roles of class I HDACi in enhancing CAR-T cell function, which provides the basis and therapeutic targets for synergic combination of CAR-T cell therapy and HDACi treatment.

Benzothiazole derivatives as histone deacetylase inhibitors for the treatment of autosomal dominant polycystic kidney disease.

Recent evidence suggests that histone deacetylases (HDACs) are important regulators of autosomal dominant polycystic kidney disease (ADPKD). In the present study, a series of benzothiazole-bearing compounds were designed and synthesized as potential HDAC inhibitors. Given the multiple participation of HDACs in ADPKD cyst progression, we embarked on a targeted screen using HeLa nuclear extracts to identify potent pan-HDAC inhibitors. Compound 26 emerged as the most efficacious candidate. Subsequent pharmacological characterization showed that compound 26 effectively inhibits several HDACs, notably HDAC1, HDAC2, and HDAC6 (IC50 < 150 nM), displaying a particularly high sensitivity towards HDAC6 (IC50 = 11 nM). The selected compound significantly prevented cyst formation and expansion in an in vitro cyst model and was efficacious in reducing cyst growth in both an embryonic kidney cyst model and an in vivo ADPKD mouse model. Our results provided compelling evidence that compound 26 represents a new HDAC inhibitor for the treatment of ADPKD.

Evaluation of 1,10-phenanthroline-based hydroxamate derivative as dual histone deacetylases/ribonucleotide reductase inhibitor with antitumor activities.

BACKGROUND: Aberrant expression of histone deacetylases (HDACs) and ribonucleotide reductase (RR) enzymes are commonly observed in various cancers. Researchers are focusing on these enzymes in cancer studies with the aim of developing effective chemotherapeutic drugs for cancer treatment. Targeting both HDAC and RR simultaneously with a dual HDAC/RR inhibitor has exhibited enhanced effectiveness compared to monotherapy in cancer treatment, making it a promising strategy. OBJECTIVES: The objective of the study is to synthesize and assess the anti-cancer properties of a 1,10-phenanthroline-based hydroxamate derivative, characterizing it as a novel dual HDAC/RR inhibitor. METHODS: The N1-hydroxy-N8-(1,10-phenanthrolin-5-yl)octanediamide (PA), a 1,10-phenanthroline-based hydroxamate derivative, was synthesized and structurally characterized. The compound was subjected to in vitro assessments of its anti-cancer, HDAC, and RR inhibitory activities. In silico docking and molecular dynamics simulations were further studied to explore its interactions with HDACs and RRM2. RESULTS: The structurally confirmed PA exhibited antiproliferative activity in SiHa cells with an IC50 of 16.43 µM. It displayed potent inhibitory activity against HDAC and RR with IC50 values of 10.80 µM and 9.34 µM, respectively. Co-inhibition of HDAC and RR resulted in apoptosis-induced cell death in SiHa cells, mediated by the accumulation of reactive oxygen species (ROS). In silico docking studies demonstrated that PA can effectively bind to the active sites of HDAC isoforms and RRM2. Furthermore, PA demonstrated a more favorable interaction with HDAC7, displaying a docking score of -9.633 kcal/mol, as compared to the standard HDAC inhibitor suberoylanilide hydroxamic acid (SAHA), which exhibited a docking score of -8.244 kcal/mol against HDAC7. CONCLUSION: The present study emphasizes the prospect of designing a potential 1,10-phenanthroline hydroxamic acid derivative as a novel dual HDAC and RR-inhibiting anti-cancer molecule.

Inhibition of HDAC6 with CAY10603 alleviates acute and chronic kidney injury by suppressing the ATF6 branch of UPR.

BACKGROUND: Histone deacetylase 6 (HDAC6) inhibitor CAY10603 has been identified as a potential therapeutic agent for the treatment of diabetic kidney disease (DKD). The objective of this study was to investigate the therapeutic effects of CAY10603 in mice with acute kidney injury (AKI) and chronic kidney diseases (CKD). METHODS: Renal immunohistology was performed to assess the expression levels of HDAC6 in both human and mouse kidney samples. C57BL/6J mice were intraperitoneal injected with lipopolysaccharide (LPS) to induce AKI; CD-1 mice were fed with adenine diet to induce adenine-nephropathy as CKD model. Serum creatinine, blood urea nitrogen and uric acid were measured to reflect renal function; renal histology was applied to assess kidney damage. Western blot and immunohistology were used to analyze the unfolded protein response (UPR) level. RESULTS: HDAC6 was significantly upregulated in renal tubular epithelial cells (RTECs) of both AKI and CKD patients as well as mice. In the murine models of AKI induced by LPS and adenine-induced nephropathy, CAY10603 exhibited notable protective effects, including improvement in biochemical indices and pathological changes. In vivo and in vitro studies revealed that CAY10603 effectively suppressed the activation of activating transcription factor 6 (ATF6) branch of UPR triggered by thapsigargin (Tg), a commonly employed endoplasmic reticulum (ER) stressor. Consistent with these findings, CAY10603 also displayed substantial inhibition of ATF6 activation in RTECs from both murine models of LPS-induced AKI and adenine-induced nephropathy. CONCLUSIONS: Collectively, these results suggest that CAY10603 holds promise as a potential therapeutic agent for both acute and chronic kidney injury.