Targeting Histone Deacetylase Research Articles

Insight in Quinazoline-based HDAC Inhibitors as Anti-cancer Agents.

Cancer remains a primary cause of death globally, and effective treatments are still limited. While chemotherapy has notably enhanced survival rates, it brings about numerous side effects. Consequently, the ongoing challenge persists in developing potent anti-cancer agents with minimal toxicity. The versatile nature of the quinazoline moiety has positioned it as a pivotal component in the development of various antitumor agents, showcasing its promising role in innovative cancer therapeutics. This concise review aims to reveal the potential of quinazolines in creating anticancer medications that target histone deacetylases (HDACs).

A potent dual inhibitor targeting COX-2 and HDAC of acute myeloid leukemia cells.

Acute myeloid leukemia (AML) is an aggressive cancer with complex issues of drug resistance and a poor prognosis; thus, effective therapeutics is urgently needed for AML. In this study, we designed and synthesized dual cyclooxygenase-2 (COX-2) and histone deacetylase (HDAC) inhibitors, IMC-HA and IMC-OPD, and applied them for the treatment of AML. IMC-HA comprised a COX-2 inhibitor skeleton of indomethacin (IMC) and an HDAC inhibitor moiety of the hydroxamic group and was found to exhibit potent antiproliferative activity against AML cells (THP-1 and U937) and low cytotoxicity toward normal cells. Molecular docking simulations suggested that IMC-HA had a high binding affinity for HDAC and COX-2, with binding energies of -6.8 and -9.0kcal/mol, respectively. Mechanistic studies revealed that IMC-HA induced apoptosis and G0/G1 phase arrest in AML cells, which were characterized by alterations in the expression of apoptotic and cell cycle-related proteins. Further study demonstrated that IMC-HA also inhibited the MEK/ERK signaling pathway in AML cells. Overall, we believe that IMC-HA could serve as a potent COX-2/HDAC dual inhibitor and improve the treatment of AML.

Novel dual inhibitor targeting CDC25 and HDAC for treating triple-negative breast cancer

Triple-negative breast cancer (TNBC) presents a significant challenge for treatment due to its aggressive nature and the lack of effective therapies. This study developed dual inhibitors against cell division cycle 25 (CDC25) and histone deacetylases (HDACs) for TNBC treatment. CDC25 phosphatases are crucial for activating cyclin-dependent kinases (CDKs), the master regulators of cell cycle progression. HDACs regulate various biological processes by deacetylating histone and non-histone proteins, affecting gene expression, chromatin structure, cell differentiation, and proliferation. Dysregulations of HDAC and CDC25 are associated with several human malignancies. We generated a group of dual inhibitors for CDC25 and HDAC by combining the molecular structures of CDC25 (quinoline-5,8-dione) and HDAC (hydroxamic acid or benzamide) pharmacophores. The newly developed compounds were evaluated against various solid-tumor, leukemia, and non-malignant breast epithelial cells. Among the synthesized compounds, 18A emerged as a potent inhibitor, demonstrating significant cytotoxicity against TNBC cells, superior to its effects on other cancer types while sparing non-malignant cells. 18A possessed similar HDAC inhibitory activity as MS-275 and potently suppressed CDC25 activity in vitro and the CDK1 dephosphorylation in cells. Additionally, 18A hindered the progression of S and G2/M phases, triggered DNA damage, and induced apoptosis. These findings underscore the potential of 18A as a targeted therapy for TNBC and warrants further preclinical development.Graphical

Histone deacetylase inhibition enhances extracellular vesicles from muscle to promote osteogenesis via miR-873-3p

Regular physical activity is widely recognized for reducing the risk of various disorders, with skeletal muscles playing a key role by releasing biomolecules that benefit multiple organs and tissues. However, many individuals, particularly the elderly and those with clinical conditions, are unable to engage in physical exercise, necessitating alternative strategies to stimulate muscle cells to secrete beneficial biomolecules. Histone acetylation and deacetylation significantly influence exercise-induced gene expression, suggesting that targeting histone deacetylases (HDACs) could mimic some exercise responses. In this study, we explored the effects of the HDAC inhibitor Trichostatin A (TSA) on human skeletal muscle myoblasts (HSMMs). Our findings showed that TSA-induced hyperacetylation enhanced myotube fusion and increased the secretion of extracellular vesicles (EVs) enriched with miR-873-3p. These TSA-EVs promoted osteogenic differentiation in human bone marrow mesenchymal stem cells (hBMSCs) by targeting H2 calponin (CNN2). In vivo, systemic administration of TSA-EVs to osteoporosis mice resulted in significant improvements in bone mass. Moreover, TSA-EVs mimicked the osteogenic benefits of exercise-induced EVs, suggesting that HDAC inhibition can replicate exercise-induced bone health benefits. These results demonstrate the potential of TSA-induced muscle-derived EVs as a therapeutic strategy to enhance bone formation and prevent osteoporosis, particularly for individuals unable to exercise. Given the FDA-approved status of various HDAC inhibitors, this approach holds significant promise for rapid clinical translation in osteoporosis treatment.

Discovery of a Novel Benzimidazole Derivative Targeting Histone Deacetylase to Induce Ferroptosis and Trigger Immunogenic Cell Death.

Ferroptosis is a unique type of cell death, characterized by its reliance on iron dependency and lipid peroxidation (LPO). Consequently, small-molecule ferroptosis modulators have garnered substantial interest as a promising avenue for cancer therapy. Herein, we explored the ferroptosis sensitivity of epigenetic modulators and found that the antiproliferative effects of class I histone deacetylase (HDAC) inhibitors are significantly reliant on ferroptosis. Subsequently, we developed a novel series of HDAC inhibitors, identifying HL-5s with robust inhibitory activity against class I HDACs, particularly HDAC1. Notably, HL-5s induces ferroptosis by augmenting LPO production. Mechanistically, HL-5s increased the YB-1 acetylation and inhibited the Nrf2/HO-1 signaling pathway. Furthermore, HL-5s not only significantly suppresses tumor growth in the PC-9 xenograft model but also remodels the tumor microenvironment in the LLC allograft model. Our study has unveiled that class I HDAC inhibitors can exert antitumor effects by triggering ferroptosis, and HL-5s may serve as a promising candidate for future cancer treatment.

Inhibition of HDAC8 mitigates AKI by reducing DNA damage and promoting homologous recombination repair.

Nephrotoxicity is a major side effect of platinum-based antineoplastic drugs, and there is currently no available therapeutic intervention. Our study suggests that targeting histone deacetylase 8 could be a potential treatment for cisplatin-induced acute kidney injury (AKI). In a murine model of AKI induced by cisplatin, the administration of PCI-34051, a selective inhibitor of HDAC8, resulted in significant improvement in renal function and reduction in renal tubular damage and apoptosis. Pharmacological inhibition of HDAC8 also decreased caspase-3 and PARP1 cleavage, attenuated Bax expression and preserved Bcl-2 levels in the injured kidney. In cultured murine renal epithelial cells (mRTECs) exposed to cisplatin, treatment with PCI-34051 or transfection with HDAC8 siRNA reduced apoptotic cell numbers and diminished expression of cleaved caspase-3 and PARP1; conversely, overexpression of HDAC8 intensified these changes. Additionally, PCI-34051 reduced p53 expression levels along with those for p21, p-CDK2 and γ-H2AX while preserving MRE11 expression in the injured kidney. Similarly, pharmacological and genetic inhibition of HDAC8 reduced γ-H2AX and enhanced MRE11 expression; conversely, HDAC8 overexpression exacerbated these changes in mRTECs exposed to cisplatin. These results support that HDAC8 inhibition attenuates cisplatin-induced AKI through a mechanism associated with reducing DNA damage and promoting its repair.

BCL6 confers resistance to HDAC inhibitors in DLBCL

Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin lymphoma with limited response to chemotherapy. Histone acetylation is reduced in DLBCL. Chidamide, a histone deacetylase inhibitor, shows promise in lymphomas but needs further investigation for DLBCL. Our study indicated that chidamide effectively suppresses DLBCL both in vitro and in vivo. High-throughput RNA sequencing analysis provided comprehensive evidence that chidamide markedly influences crucial signaling pathways in DLBCL, including the MAPK, MYC and p53 pathway. Additionally, we observed substantial variability in the sensitivity of DLBCL cells to chidamide, and identified that elevated expression of BCL6 might confer resistance to chidamide in DLBCL. Moreover, our investigations revealed that BCL6 inhibited chidamide-induced histone acetylation by recruiting histone deacetylase (HDACs), leading to drug resistance in DLBCL cells. Furthermore, we found that lenalidomide targeted BCL6 degradation through the ubiquitination pathway and restore the sensitivity of drug-resistant DLBCL to chidamide. Collectively, these findings provided valuable insights into the global impact of chidamide on DLBCL and highlight the potential of targeting HDACs as a therapeutic strategy for DLBCL. Identifying BCL6 as a biomarker for predicting the response to chidamide and the combination therapy with BCL6 inhibition has the potential to lead to more personalized and effective treatments for DLBCL patients.

Targeting histone deacetylase 1 (HDAC1) in the bone marrow stromal cells revers imatinib resistance by modulating IL-6 in Ph + acute lymphoblastic leukemia.

Bone marrow stromal cells (BMSCs) can promote the growth of Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). Histone deacetylases (HDACs) play essential roles in the proliferation and apoptosis resistance of Ph + ALL cells. In our previous study, inhibiting histone deacetylase 1 (HDAC1) decreases the proliferation of Ph + ALL cells. However, little is known regarding how HDAC1 in BMSCs of Ph + ALL patients affects the imatinib (IM) resistance. Therefore, the present work examined the roles of HDAC1 in BMSCs. Overexpression of HDAC1 was found in BMSCs of Ph + ALL patients with IM resistance. In addition, the Ph + ALL cell line SUP-B15 was co-cultured with BMSCs after lentivirus transfection for regulating HDAC1 expression. Knockdown of HDAC1 within BMSCs elevated the IM-mediated SUP-B15 cell apoptosis, while increasing HDAC1 expression had an opposite effect. IL-6 in BMSCs, which is an important factor for the microenvironment-associated chemoresistance, showed evident up-regulation in HDAC1-upregulated BMSCs and down-regulation in HDAC1-downregulated BMSCs. While recombinant IL-6 (rIL-6) can reversed the sensitivity of SUP-B15 cells to IM induced by downregulating HDAC1 expression in BMSCs. HDAC1 showed positive regulation on IL-6 transcription and secretion. Moreover, IL-6 secretion induced by HDAC1 in BMSCs might enhance IM resistance in Ph + ALL cells. With regard to the underlying molecular mechanism, NF-κB, an important signal responsible for IL-6 transcription in BMSCs, mediated the HDAC1-regulated IL-6 expression. Collectively, this study facilitated to develop HDAC1 inhibitors based not only the corresponding direct anti-Ph + ALL activity but also the regulation of bone marrow microenvironment.

Selective HDAC6 Inhibition Has the Potential for Anti-Cancer Effect in Renal Cell Carcinoma.

Despite significant advancements in systemic therapy for renal cell carcinoma (RCC), the prognosis for patients with metastatic RCC remains poor, as they are often incurable. Consequently, there is an urgent need for innovative therapeutic strategies to further enhance the efficacy of RCC treatment and improve patient outcomes. One such promising avenue lies in targeting histone deacetylase (HDAC) 6, a protein known to regulate numerous crucial biological processes implicated in cancer progression by modulating the acetylation status of various cytoplasmic proteins. To explore the therapeutic potential of HDAC6 inhibition in RCC, our study focused on investigating the effects of HDAC6 inhibitors on cultured RCC cells. Utilizing a panel of 12 small molecule selective HDAC6 inhibitors and employing genetic knockdown techniques, we examined the impact of HDAC6 inhibition on RCC cellular dynamics. Our findings revealed that HDAC6 inhibition exerted a profound effect on RCC cells, resulting in decreased cell viability and DNA replication. Importantly, this effect was attributed to the induction of apoptosis. Our study provides valuable insights into the mechanisms underlying the anticancer effects of selective HDAC6 inhibitors on RCC. A detailed understanding of the molecular mechanisms underlying the anticancer effects of HDAC6 inhibition is important to explore new therapeutic strategies for metastatic RCC.

Targeting histone deacetylase in cardiac diseases.

Histone deacetylases (HDAC) catalyze the removal of acetylation modifications on histones and non-histone proteins, which regulates gene expression and other cellular processes. HDAC inhibitors (HDACi), approved anti-cancer agents, emerge as a potential new therapy for heart diseases. Cardioprotective effects of HDACi are observed in many preclinical animal models of heart diseases. Genetic mouse models have been developed to understand the role of each HDAC in cardiac functions. Some of the findings are controversial. Here, we provide an overview of how HDACi and HDAC impact cardiac functions under physiological or pathological conditions. We focus on in vivo studies of zinc-dependent classical HDACs, emphasizing disease conditions involving cardiac hypertrophy, myocardial infarction (MI), ischemic reperfusion (I/R) injury, and heart failure. In particular, we review how non-biased omics studies can help our understanding of the mechanisms underlying the cardiac effects of HDACi and HDAC.

Targeting histone deacetylase 6 (HDAC6) to enhance radiation therapy in meningiomas in a 2D and 3D in vitro study

External radiation therapy (RT) is often a primary treatment for inoperable meningiomas in the absence of established chemotherapy. Histone deacetylase 6 (HDAC6) overexpression, commonly found in cancer, is acknowledged as a driver of cellular growth, and inhibiting HDACs holds promise in improving radiotherapeutic efficacy. Downregulation of HDAC6 facilitates the degradation of β-catenin. This protein is a key element in the Wnt/β-catenin signalling pathway, contributing to the progression of meningiomas. In order to elucidate the associations and therapeutic potential of HDAC6 inhibitors (HDAC6i) in conjunction with RT, we administered Cay10603, HDAC6i, to both immortalised and patient-derived meningioma cells prior to RT in this study. Our findings reveal an increase in HDAC6 expression following exposure to RT, which is effectively mitigated with pre-treated Cay10603. The combination of Cay10603 with RT resulted in a synergistic augmentation of cytotoxic effects, as demonstrated through a range of functional assays conducted in both 2D as well as 3D settings; the latter containing syngeneic tumour microenvironment (TME). Radiation-induced DNA damage was augmented by pre-treatment with Cay10603, concomitant with the inhibition of β-catenin and minichromosome maintenance complex component 2 (MCM2) accumulation within the nucleus. This subsequently inhibited c-myc oncogene expression. Our findings demonstrate the therapeutic potential of Cay10603 to improve the radiosensitisation and provide rationale for combining HDAC6i with RT for the treatment of meningioma. This work was funded by Brain Tumour Research Centre of Excellence award to C Oliver Hanemann.

Psammaplin A analogues with modified disulfide bond targeting histone deacetylases: Synthesis and biological evaluation

Psammaplin A (PsA), a symmetrical bromotyrosine-derived disulfide marine metabolite, has been reported could inhibit HDAC1/2/3 through its thiol monomer. Inspired by the disuflide bond structure of this marine natural product, we designed and synthesized a series of PsA analogues, in which the disulfide bond of PsA was replaced with diselenide bond or cyclic disulfide/diselenide/selenenylsulfide motifs. We also studied the HDAC inhibition, cell growth inhibition, and apoptosis induction of these PsA analogues. The results showed that, all the synthetic diselenide analogues and cyclic selenenyl sulfide compounds exhibited better antiproferative activity than their counterpart of disulfide analogues. Among the prepared analogues, diselenide analogue P-503 and P-116 significantly increased the ability of inhibiting HDAC6 and induced apoptosis and G2/M cell cycle arrest. However, cyclic selenenylsulfides analogues P-111 lost its HDAC inhibitory ability and exhibited no effect on cell cycle and apoptosis, indicating that the anti-proliferative mechanism of cyclic selenenylsulfides analogues has changed.

Investigating neuroepigenetic alterations in chronic low back pain with positron emission tomography.

Epigenetics has gained considerable interest as potential mediators of molecular alterations that could underlie the prolonged sensitization of nociceptors, neurons, and glia in response to various environmental stimuli. Histone acetylation and deacetylation, key processes in modulating chromatin, influence gene expression; elevated histone acetylation enhances transcriptional activity, whereas decreased acetylation leads to DNA condensation and gene repression. Altered levels of histone deacetylase (HDAC) have been detected in various animal pain models, and HDAC inhibitors have demonstrated analgesic effects in these models, indicating HDACs' involvement in chronic pain pathways. However, animal studies have predominantly examined epigenetic modulation within the spinal cord after pain induction, which may not fully reflect the complexity of chronic pain in humans. Moreover, methodological limitations have previously impeded an in-depth study of epigenetic changes in the human brain. In this study, we employed [ 11 C]Martinostat, an HDAC-selective radiotracer, positron emission tomography to assess HDAC availability in the brains of 23 patients with chronic low back pain (cLBP) and 11 age-matched and sex-matched controls. Our data revealed a significant reduction of [ 11 C]Martinostat binding in several brain regions associated with pain processing in patients with cLBP relative to controls, highlighting the promising potential of targeting HDAC modulation as a therapeutic strategy for cLBP.

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

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. 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. 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. The structurally confirmed PA exhibited antiproliferative activity in SiHa cells with an IC50 of 16.43μM. It displayed potent inhibitory activity against HDAC and RR with IC50 values of 10.80μM and 9.34μM, 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 -9.633kcal/mol, as compared to the standard HDAC inhibitor suberoylanilide hydroxamic acid (SAHA), which exhibited a docking score of -8.244kcal/mol against HDAC7. 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.

Investigating Potential Cancer Therapeutics: Insight into Histone Deacetylases (HDACs) Inhibitions.

Histone deacetylases (HDACs) are enzymes that remove acetyl groups from ɛ-amino of histone, and their involvement in the development and progression of cancer disorders makes them an interesting therapeutic target. This study seeks to discover new inhibitors that selectively inhibit HDAC enzymes which are linked to deadly disorders like T-cell lymphoma, childhood neuroblastoma, and colon cancer. MOE was used to dock libraries of ZINC database molecules within the catalytic active pocket of target HDACs. The top three hits were submitted to MD simulations ranked on binding affinities and well-occupied interaction mechanisms determined from molecular docking studies. Inside the catalytic active site of HDACs, the two stable inhibitors LIG1 and LIG2 affect the protein flexibility, as evidenced by RMSD, RMSF, Rg, and PCA. MD simulations of HDACs complexes revealed an alteration from extended to bent motional changes within loop regions. The structural deviation following superimposition shows flexibility via a visual inspection of movable loops at different timeframes. According to PCA, the activity of HDACs inhibitors induces structural dynamics that might potentially be utilized to define the nature of protein inhibition. The findings suggest that this study offers solid proof to investigate LIG1 and LIG2 as potential HDAC inhibitors.

Current treatment strategies targeting histone deacetylase inhibitors in acute lymphocytic leukemia: a systematic review.

Acute lymphocytic leukemia is a hematological malignancy that primarily affects children. Long-term chemotherapy is effective, but always causes different toxic side effects. With the application of a chemotherapy-free treatment strategy, we intend to demonstrate the most recent results of using one type of epigenetic drug, histone deacetylase inhibitors, in ALL and to provide preclinical evidence for further clinical trials. In this review, we found that panobinostat (LBH589) showed positive outcomes as a monotherapy, whereas vorinostat (SAHA) was a better choice for combinatorial use. Preclinical research has identified chidamide as a potential agent for investigation in more clinical trials in the future. In conclusion, histone deacetylase inhibitors play a significant role in the chemotherapy-free landscape in cancer treatment, particularly in acute lymphocytic leukemia.

Unveiling Epigenetic Vulnerabilities in Triple-Negative Breast Cancer through 3D Organoid Drug Screening.

Triple-negative breast cancer (TNBC) poses a therapeutic challenge due to its aggressive nature and lack of targeted therapies. Epigenetic modifications contribute to TNBC tumorigenesis and drug resistance, offering potential therapeutic targets. Recent advancements in three-dimensional (3D) organoid cultures, enabling precise drug screening, hold immense promise for identifying novel compounds targeting TNBC. In this study, we established two patient-derived TNBC organoids and implemented a high-throughput drug screening system using these organoids and two TNBC cell lines. Screening a library of 169 epigenetic compounds, we found that organoid-based systems offer remarkable precision in drug response assessment compared to cell-based models. The top 30 compounds showing the highest drug sensitivity in the initial screening were further assessed in a secondary screen. Four compounds, panobinostat, pacritinib, TAK-901, and JIB-04, targeting histone deacetylase, JAK/STAT, histone demethylases, and aurora kinase pathways, respectively, exhibited potent anti-tumor activity in TNBC organoids, surpassing the effect of paclitaxel. Our study highlights the potential of these novel epigenetic drugs as effective therapeutic agents for TNBC and demonstrates the valuable role of patient-derived organoids in advancing drug discovery.

Synthesis of Cinnamoylhydroxamic Acid Derivatives Bearing Sulfonamide, Amide Bonds as Connecting Unit Targeting Histone Deacetylases

Based on the strong activity of belinostat, the study synthesized of some cinnamoylhydroxamic acid derivatives with the aim of creating new compounds that have the potential to selectively inhibit HDAC to contribute to cancer treatment. N-hydroxycinnamamide serves as both ZBG and the linker group. The derivatives orient to the HDAC2 and HDAC8 enzymes by molecular docking. Compound 9a (bearing sulfonamide) exhibited as the most potential candidate to inhibit the function of HDAC2 enzyme.

Abstract A033: The ING5 epigenetic reader regulates a subset of DNA repair genes to maintain genomic integrity

Abstract The ING family of epigenetic histone code readers (ING1-5) recognize the H3K4Me3 epigenetic mark to target histone acetyltransferase (HAT) or histone deacetylase (HDAC) complexes to regulate local acetylation levels and affect transcription. We and others have shown that ING5 promotes stem cell character in normal and in cancer stem cells and that loss of ING5 promotes stem cell differentiation. Examination of an ING5 knockout (KO) mouse model showed increased levels of DNA damage in different tissues, and particularly in the male germ line. ING5 mouse embryo fibroblasts (MEFs) also show a >2-fold increase in cells containing gH2AX foci in the absence of exogenous DNA damaging agents. Examining the transcriptomes of ING5 KO and wild-type littermate MEFs indicates that several genes encoding key DNA repair proteins such as those acting in homologous recombination (BRCA1 and BRCA2) and base excision repair (PARP1) are repressed several-fold and ING5 KO MEFs show increased sensitivity to the PARP inhibitor olaparib. Given that ING5 functions to help maintain stem cell character in normal and in cancer stem cells, we propose that ING5 serves a role in maintaining a high level of DNA repair capability in stem cell populations to preserve genomic integrity. Citation Format: Arthur E Dantas, Buthaina Al-Shueili, Mahbod Djamshidi, Karl Riabowol. The ING5 epigenetic reader regulates a subset of DNA repair genes to maintain genomic integrity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr A033.

HDAC/NAMPT dual inhibitors overcome initial drug-resistance in p53-null leukemia cells

The occurrence of cancer is closely related to metabolism and epigenetics. Histone deacetylases (HDACs) play a crucial role in the regulation of gene expression as epigenetic regulators, while nicotinamide phosphoribosyltransferase (NAMPT) is significantly involved in maintaining cellular metabolism. In this study, we rationally designed a series of novel HDAC/NAMPT dual inhibitors based on the structural similarity between HDAC and NAMPT inhibitors. The representative compounds 39a and 39h exhibit significant selective inhibitory activity on HDAC1-3 with IC50 values of 0.71–25.1 nM, while displaying modest activity against NAMPT. Compound 39h did not exhibit inhibitory activity against 370 kinases, demonstrating its target specificity. These two compounds exhibit potent anti-proliferative activity in multiple leukemia cell lines with low nanomolar IC50s. It is worth noticing that the dual inhibitors 39a and 39h overcome the primary resistance of HDAC or NAMPT single target inhibitor in p53-null AML cell lines, with the induction of apoptosis-related cell death. NMN recovers the cell death induced by HDAC/NAMPT dual inhibitors, which indicates the lethal effects are caused by the inhibition of NAD biosynthesis pathway as well as HDAC. This research provides an effective strategy to overcome the limitations of HDAC inhibitors in treating p53-null leukemia.