Histone deacetylases (HDACs) as the promising immunotherapeutic targets for hematologic cancer treatment

Epigenetic activation of PTEN by valproic acid inhibits PI3K/AKT signaling and Burkitt lymphoma cell growth

Histone deacetylase (HDAC) inhibitors show promise in treating Burkitt lymphoma (BL), although the precise mechanisms remain unclear. We investigated the effects of valproic acid (VPA), a specific HDAC inhibitor, on BL cell lines RAJI and CA46, focusing on the PTEN/PI3K/AKT pathway. Cell viability, cell cycle progression, and apoptosis were evaluated using the Cell Counting Kit-8 assay and the Annexin V-fluorescein isothiocyanate assay. Chromatin immunoprecipitation sequencing (ChIP-seq) assessed acetylation at the PTEN promoter, while gene expression and protein levels were measured via reverse transcription quantitative polymerase chain reaction and Western blotting, respectively. VPA treatment significantly reduced BL cell viability and induced apoptosis and cell cycle arrest in a dose-dependent manner. Compared to peripheral blood mononuclear cells, BL cells exhibited significantly higher HDAC mRNA and protein levels. ChIP-seq analysis revealed increased acetylation of the PTEN promoter following exposure to VPA. After treatment with 4 mM VPA, PTEN protein levels in BL cells increased significantly, while levels of HDAC, p-AKT, and p-p70S6K proteins decreased markedly. Furthermore, compared to VPA treatment alone, the combination of VPA and the PI3K inhibitor BEZ235 led to even greater PTEN protein expression, further decreased p-AKT and p-p70S6K protein levels, and further reduced cell viability in BL cells. VPA exerts its antitumor effects in BL cells by modulating the PTEN/PI3K/AKT pathway through the inhibition of HDAC1.

JBI-802: the first orally available LSD1/HDAC6 dual inhibitor to enter clinical trials

INTRODUCTION

Lysine-specific demethylase 1 (LSD1) and histone deacetylase 6 (HDAC6) are key epigenetic regulators involved in histone demethylation and deacetylation processes that impact chromatin structure and gene expression. JBI-802 marks a major advancement as the first novel, orally available LSD1/HDAC6 dual inhibitor currently in clinical trials.

AREAS COVERED

This review provides a comprehensive overview of the discovery and development of JBI-802, detailing its structure-activity relationship (SARs), chemical synthesis, biological activity, and clinical progress. Other dual LSD1/HDAC6 inhibitors and the challenges are briefly discussed, underscoring the therapeutic potential of dual inhibition in disease treatment. The literature search is performed using SciFinder, Google patent, ClinicalTrials databases, and PubMed.

EXPERT OPINION

The dual LSD1/HDAC6 inhibitor JBI-802 demonstrates robust anti-proliferative activity, significant antitumor effects in multiple hematologic malignancies, and superior efficacy in combination with checkpoint inhibitors in the CT-26 syngeneic mouse model. JBI-802 is currently undergoing phase I/II clinical trials in patients with advanced solid tumors, myeloproliferative neoplasms (MPN), and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) with thrombocytosis. However, the potential on-target toxicity, off-target interactions and selectivity concerns deservee more attention.

Synthesis and Antitumor Evaluation of a Novel Class of Chalcone Mannich Base Derivatives

A novel class of chalcone Mannich base derivatives I1-9 and II1-11 was synthesized, which exhibited significant antiproliferation activities in five different cancer cells. The activities of most compounds were superior to those of the positive control drug 5-FU. Moreover, compared with the intermediate chalcone, their water solubility was also significantly enhanced. Among them, the most prospective compound I4 (IC50 = 3.09-5.08 μM for the tested cancer cells) can effectively inhibit the proliferation of A549/DDP cells (IC50 = 4.69 μM). Further mechanistic studies revealed that it can induce apoptosis of A549 and A549/DDP cells by arresting the G2/M phase of the cell cycle. Although the selectivity of compound I4 between tumor cells and normal cells was not obvious, it might be a promising lead compound for lung cancer and is worthy of further investigation.

Bromodomain proteins as potential therapeutic targets for B-cell non-Hodgkin lymphoma

BACKGROUND

B-cell non-Hodgkin lymphoma (B-NHL) is the most common type of lymphoma and is significantly heterogeneous among various subtypes. Despite of considerable advancements in treatment strategies for B-NHL, the prognosis of relapsed/refractory patients remains poor.

MAIN TEXT

It has been indicated that epigenetic dysregulation is critically associated with the pathogenesis of most hematological malignancies, resulting in the clinical targeting of epigenetic modifications. Bromodomain (BRD) proteins are essential epigenetic regulators which contain eight subfamilies, including BRD and extra-terminal domain (BET) family, histone acetyltransferases (HATs) and HAT-related proteins, transcriptional coactivators, transcriptional mediators, methyltransferases, helicases, ATP-dependent chromatin-remodeling complexes, and nuclear-scaffolding proteins. Most pre-clinical and clinical studies on B-NHL have focused predominantly on the BET family and the use of BET inhibitors as mono-treatment or co-treatment with other anti-tumor drugs. Furthermore, preclinical models of B-NHL have revealed that BET degraders are more active than BET inhibitors. Moreover, with the development of BET inhibitors and degraders, non-BET BRD protein inhibitors have also been designed and have shown antitumor activities in B-NHL preclinical models. This review summarized the mechanism of BRD proteins and the recent progress of BRD protein-related drugs in B-NHL. This study aimed to collect the most recent evidences and summarize possibility on whether BRD proteins can serve as therapeutic targets for B-NHL.

CONCLUSION

In summary, BRD proteins are critical epigenetic regulatory factors and may be potential therapeutic targets for B-NHL.

The genetically predicted causal associations between circulating 3-hydroxybutyrate levels and malignant neoplasms: A pan-cancer Mendelian randomization study

OBJECTIVE

The ketogenic diet or exogenous supplementation with 3-hydroxybutyrate (3HB) is progressively gaining recognition as a valuable therapeutic or health intervention strategy. However, the effects of 3HB on cancers have been inconsistent in previous studies. This study aimed to comprehensively investigate the causal effects of circulating 3HB levels on 120 cancer phenotypes, and explore the 3HB mediation effect between liver fat accumulation and cancers.

METHODS

Univariate Mendelian randomization (UVMR) was used in this study to investigate the causal impact of circulating 3HB levels on cancers. We conducted meta-analyses for 3HB-cancer associations sourced from different exposure data. In multivariate MR(MVMR), the body mass index, alcohol frequency and diabetes were included as covariates to investigate the independent effect of 3HB on cancer risk. Additionally, utilizing mediation MR analysis, we checked the potential mediating role of 3HB in the association between liver fat and cancer.

RESULTS

Integrating findings from UVMR and MVMR, we observed that elevated circulating 3HB levels were associated with reduced risk of developing diffuse large B-cell lymphoma(DLBCL) (OR[95%CI] = 0.28[0.14-0.57] p = 3.92e-04), biliary malignancies (OR[95%CI] = 0.30[0.15-0.60], p = 7.67e-04), hepatocellular carcinoma(HCC) (OR[95%CI] = 0.25[0.09-0.71], p = 9.33e-03), primary lymphoid and hematopoietic malignancies (OR[95%CI] = 0.76[0.58-0.99], p = 0.045). Further UVMR analysis revealed that an increase in the percent liver fat was associated with reduced 3HB levels (Beta[95%CI] = -0.073[-0.122∼-0.024], p = 0.0034) and enhanced susceptibility to HCC (OR[95%CI] = 13.9[9.76-19.79], p = 3.14e-48), biliary malignancies (OR[95%CI] = 4.04[3.22-5.07], p = 1.64e-33), nasopharyngeal cancer (OR[95%CI] = 3.26[1.10-9.67], p = 0.03), and primary lymphoid and hematopoietic malignancies (OR[95%CI] = 1.27[1.13-1.44], p = 1.04e-4). Furthermore, 3HB fully mediated the effect of liver fat on susceptibility to DLBCL (OR[95%CI] = 1.076[1.01-1.15], p = 0.034).

CONCLUSIONS

Circulating 3HB is associated with a reduced susceptibility to developing DLBCL, HCC, biliary malignancies, and primary lymphoid and hematopoietic malignancies. The impaired ketogenesis induced by metabolic-dysfunction associated fatty liver disease (MAFLD) contributes to risk of DLBCL.

Discovery of Potent Selective HDAC6 Inhibitors with 5-Phenyl-1H-indole Fragment: Virtual Screening, Rational Design, and Biological Evaluation

Among the HDACs family, histone deacetylase 6 (HDAC6) has attracted extensive attention due to its unique structure and biological functions. Numerous studies have shown that compared with broad-spectrum HDACs inhibitors, selective HDAC6 inhibitors exert ideal efficacy in tumor treatment with insignificant toxic and side effects, demonstrating promising clinical application prospect. Herein, we carried out rational drug design by integrating a deep learning model, molecular docking, and molecular dynamics simulation technology to construct a virtual screening process. The designed derivatives with 5-phenyl-1H-indole fragment as Cap showed desirable cytotoxicity to the various tumor cell lines, all of which were within 15 μM (ranging from 0.35 to 14.87 μM), among which compound 5i had the best antiproliferative activities against HL-60 (IC50 = 0.35 ± 0.07 μM) and arrested HL-60 cells in the G0/G1 phase. In addition, 5i exhibited better isotype selective inhibitory activities due to the potent potency against HDAC6 (IC50 = 5.16 ± 0.25 nM) and the reduced inhibitory activities against HDAC1 (selective index ≈ 124), which was further verified by immunoblotting results. Moreover, the representative binding conformation of 5i on HDAC6 was revealed and the key residues contributing 5i's binding were also identified via decomposition free-energy analysis. The discovery of lead compound 5i also indicates that virtual screening is still a beneficial tool in drug discovery and can provide more molecular skeletons with research potential for drug design, which is worthy of widespread application.

Histone deacetylase 6 as 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.

Targeting HDACs for diffuse large B-cell lymphoma therapy

Histone deacetylases (HDACs) are involved in tumorigenesis and progression, however, their role in diffuse large B-cell lymphoma (DLBCL) is not well understood. In this study, we examined the expression levels, mutations, and clinical significance of HDACs in DLBCL. Additionally, we investigated the therapeutic potential of Chidamide, a novel HDAC inhibitor, to provide scientific evidence for targeting HDACs in DLBCL patients. We extracted transcriptome data of DLBCLs--including 47 lymph node samples and 337 whole-blood-cell controls--from The Cancer Genome Atlas. Bioinformatic analyses of HDAC expression, mutation, and correlation with the clinical significance of DLBCL patients were performed with the Gene Expression Profiling Interactive Analysis, GENEMANIA, and web-based software including cBioPortal and WebGestalt. To examine the therapeutic effect of Chidamide, DLBCL cell lines (WSU-DLCL-2 and DB cells) were employed. Cell proliferation and apoptosis were analyzed with Cell Counting Kit-8 and flow cytometry assays. The impact of Chidamide treatment was also analyzed by RNA sequencing of treated DB cells. Western blot was used to explore the molecular mechanism of the cytotoxicity of Chidamide on DLBCL cell lines. The expression of some HDACs (HDAC1, 2, 3, 4, 6, 7, 8, and 9) were significantly higher in the lymph node samples of DLBCL than that in whole-blood-cell controls. Moreover, we found that the mutation rate of HDACs was also higher in DLBCL tissues, although the overall survival of DLBCL patients was not associated with HDAC expression. Chidamide was found to have a cytotoxic effect on DLBCL cells in a dose-dependent manner, while transcriptome analysis and western blot revealed that using it for treatment impacted several biological processes, including PI3K/AKT signaling, mTOR signaling, the cell cycle, and apoptosis pathways. Alterations of HDAC genes, including enhanced expression and mutations, are positively related to DLBCL. Targeting HDACs with specific inhibitors such as Chidamide may represent a potential therapeutic approach for DLBCL patients.

Synthesis and antitumor activity evaluation of coumarin Mannich base derivatives

Twenty-one new coumarin Mannich base derivatives (11a-u) were synthesized, which exhibited antiproliferation activities in HepG2 (liver cancer), A549 (lung cancer), MCF-7 (breast cancer), and HT-29 (colon cancer). Most of the target compounds showed the most potent activity against HepG2 cells compared with other cancer cells, compound 11g showed the strongest antiproliferative activity (2.10 μM) against HepG2, even superior to the positive control drug 5-FU(5.49 μM). The nitric oxide (NO) release of all compounds in HepG2 cells was determined, of which compound 11g showed high levels of NO release (10.8 μM). Notably, the solubility of compound 11g increased 13-fold compared with the lead 8. The preliminary cytotoxicity studies suggest that 11g had little effect on LO2 cells(normal liver cells, >50 μM). The effect of compound 11g on the apoptosis of HepG2 cells was also studied, and the results showed that the induction effect of compound 11g on apoptosis is a concentration-dependent manner. Our results indicate that compound 11g might be a promising lead for further studies.

Hydroxamic acid hybrids: Histone deacetylase inhibitors with anticancer therapeutic potency

Histone deacetylases (HDACs), a class of enzymes responsible for the removal of acetyl functional groups from the lysine residues in the amino-terminal tails of core histones, play a critical role in the modulation of chromatin architecture and the regulation of gene expression. Dysregulation of HDAC expression has been closely associated with the development of various cancers. Histone deacetylase inhibitors (HDACis) could regulate diverse cellular pathways, cause cell cycle arrest, and promote programmed cell death, making them promising avenues for cancer therapy with potent efficacy and favorable toxicity profiles. Hybrid molecules incorporating two or more pharmacophores in one single molecule, have the potential to simultaneously inhibit two distinct cancer targets, potentially overcome drug resistance and minimize drug-drug interactions. Notably, hydroxamic acid hybrids, exemplified by fimepinostat and tinostamustine as potential HDACis, could exert the anticancer effects through induction of apoptosis, differentiation, and growth arrest in cancer cells, representing useful scaffolds for the discovery of novel HDACis. The purpose of this review is to summarize the current scenario of hydroxamic acid hybrids as HDACis with anticancer therapeutic potential developed since 2020 to facilitate further rational exploitation of more effective candidates.

Knowledge mapping of immunotherapy for thyroid cancer from 1980 to 2022: A review

With the gradual development of immunotherapy for thyroid cancer, relevant research has increased. To better understand the current situation, development trend, evolution process, and research hotspots of this field, we conducted this comprehensive bibliometrics visual analysis. We retrieved papers published from 1980 to 2022 from Web of Science Core Collection on January 31, 2023. CiteSpace, Pajek, VOSviewer, R-Bibliometrix, and Scimago Graphics are the tools to perform the analysis. Analysis methods mainly include co-occurrence analysis and cluster analysis. Analysis objects are countries or regions, institutions, authors, journals, and keywords, etc. In terms of publication number, the recent decade has witnessed rapid growth. USA was the most prolific country and has the most influence in the cooperation team. Sweden took the lead in focus on this research field and lasted for 21 years. Garden State Cancer Center was released most papers (28). INSERM played a major role in institutional cooperation. Goldenberg DM published the most papers (48), with H-Index 25 and G-Index 43. Journal of Nuclear Medicine has the greatest papers published (41). The average impactor factor of the top 10 journals is 7.2058. The top keywords with high burst strength are: radioimmunotherapy (14.85), monoclonal antibody (13.78), non hodgkins lymphoma (12.54). The research field of immunotherapy for thyroid cancer will be further developed. This study provides a valuable reference for future research in the field.

Targeting histone deacetylases for heart diseases

Histone deacetylases (HDACs) are responsible for the deacetylation of lysine residues in histone or non-histone substrates, leading to the regulation of many biological functions, such as gene transcription, translation and remodeling chromatin. Targeting HDACs for drug development is a promising way for human diseases, including cancers and heart diseases. In particular, numerous HDAC inhibitors have revealed potential clinical value for the treatment of cardiac diseases in recent years. In this review, we systematically summarize the therapeutic roles of HDAC inhibitors with different chemotypes on heart diseases. Additionally, we discuss the opportunities and challenges in developing HDAC inhibitors for the treatment of cardiac diseases.

Discovery of novel, potent, and orally bioavailable HDACs inhibitors with LSD1 inhibitory activity for the treatment of solid tumors

Histone deacetylases (HDACs) and lysine-specific demethylase 1 (LSD1) are attractive targets for epigenetic cancer therapy. There is an intimate interplay between the two enzymes. HDACs inhibitors have shown synergistic anticancer effects in combination with LSD1 inhibitors in several types of cancer. Herein, we describe the discovery of compound 5e, a highly potent HDACs inhibitor (HDAC1/2/6/8; IC₅₀ = 2.07/4.71/2.40/107 nM) with anti-LSD1 potency (IC₅₀ = 1.34 μM). Compound 5e exhibited marked antiproliferative activity in several cancer cell lines. 5e effectively induced mitochondrial apoptosis with G2/M phase arrest, inhibiting cell migration and invasion in MGC-803 and HCT-116 cancer cells. It also showed good liver microsomal stability and acceptable pharmacokinetic parameters in SD rats. More importantly, orally administered compound 5e demonstrated higher in vivo antitumor efficacy than SAHA in the MGC-803 (TGI = 71.5%) and HCT-116 (TGI = 57.6%) xenograft tumor models accompanied by good tolerability. This study provides a novel lead compound with dual inhibitory activity against HDACs and LSD1 to further develop epigenetic drugs for solid tumor therapy. Further optimization is needed to improve the LSD1 activity to achieve dual inhibitors with balanced potency on LSD1 and HDACs.