Acute myeloid leukemia (AML) is a hematologic malignancy characterized by infiltration of the blood and bone marrow, exhibiting a low remission rate and high recurrence rate. Current research has demonstrated that class I HDAC inhibitors can downregulate anti-apoptotic proteins, leading to apoptosis of AML cells. In the present investigation, we conducted structural modifications of marine cytotoxin Santacruzamate A (SCA), a compound known for its inhibitory activity towards HDACs, resulting in the development of a novel series of potent class I HDACs hydrazide inhibitors. Representative hydrazide-based compound 25c exhibited concentration-dependent induction of apoptosis in AML cells as a single agent. Moreover, 25c exhibited a synergistic anti-AML effect when combined with Venetoclax, a clinical Bcl-2 inhibitor employed in AML therapy. This combination resulted in a more pronounced downregulation of anti-apoptotic proteins Mcl-1 and Bcl-xL, along with a significant upregulation of the pro-apoptotic protein cleaved-caspase3 and the DNA double-strand break biomarker γ-H2AX compared to monotherapy. These results highlighted the potential of 25c as a promising lead compound for AML treatment, particularly when used in combination with Venetoclax.

Histone deacetylase 1 (HDAC1), a class I HDAC enzyme, is crucial for histone modification. Currently, it is emerged as one of the important biological targets for designing small molecule drugs through cancer epigenetics. Along with synthetic inhibitors different natural inhibitors are showing potential HDAC1 inhibitions. In order to gain insights into the relationship between the molecular structures of the natural inhibitors and HDAC1, different molecular modelling techniques (Bayesian classification, recursive partitioning, molecular docking and molecular dynamics simulations) have been applied on a dataset of 155 HDAC1 nature-inspired inhibitors with diverse scaffolds. The Bayesian study showed acceptable ROC values for both the training set and test sets. The Recursive partitioning study produced decision tree 1 with 6 leaves. Further, molecular docking study was processed for generating the protein ligand complex which identified some potential amino acid residues such as F205, H28, L271, P29, F150, Y204 for the binding interactions in case of natural inhibitors. Stability of these HDAC1-natutal inhibitors complexes has been also evaluated by molecular dynamics simulation study. The current modelling study is an attempt to get a deep insight into the different important structural fingerprints among different natural compounds modulating HDAC1 inhibition.Communicated by Ramaswamy H. Sarma.

Subclinical hypothyroidism (SCH) in pregnancy is the most common form of thyroid dysfunction in pregnancy, which can affect fetal nervous system development and increase the risk of neurodevelopmental disorders after birth. However, the mechanism of the effect of maternal subclinical hypothyroidism on fetal brain development and behavioral phenotypes is still unclear and requires further study. In this study, we constructed a mouse model of maternal subclinical hypothyroidism by exposing dams to drinking water containing 50 ppm propylthiouracil (PTU) during pregnancy and found that its offspring were accompanied by severe cognitive deficits by behavioral testing. Mechanistically, gestational SCH resulted in the upregulation of protein expression and activity of HDAC1/2/3 in the hippocampus of the offspring. ChIP analysis revealed that H3K9ac on the neurogranin (Ng) promoter was reduced in the hippocampus of the offspring of SCH, with a significant reduction in Ng protein, leading to reduced expression levels of synaptic plasticity markers PSD95 (a membrane-associated protein in the postsynaptic density) and SYN (synaptophysin, a specific marker for presynaptic terminals), and impaired synaptic plasticity. In addition, administration of MS-275 (an HDAC1/2/3-specific inhibitor) to SCH offspring alleviated impaired synaptic plasticity and cognitive dysfunction in offspring. Thus, our study suggests that maternal subclinical hypothyroidism may mediate offspring cognitive dysfunction through the HDAC1/2/3-H3K9ac-Ng pathway. Our study contributes to the understanding of the signaling mechanisms underlying maternal subclinical hypothyroidism-mediated cognitive impairment in the offspring.

Upregulation of PRAME (preferentially expressed antigen of melanoma) has been implicated in the progression of a variety of cancers, including melanoma. The tumor suppressor p53 is a transcriptional regulator that mediates cell cycle arrest and apoptosis in response to stress signals. Here, we report that PRAME is a novel repressive target of p53. This was supported by analysis of melanoma cell lines carrying wild-type p53 and human melanoma databases. mRNA expression of PRAME was downregulated by p53 overexpression and activation using DNA-damaging agents, but upregulated by p53 depletion. We identified a p53-responsive element (p53RE) in the promoter region of PRAME. Luciferase and ChIP assays showed that p53 represses the transcriptional activity of the PRAME promoter and is recruited to the p53RE together with HDAC1 upon etoposide treatment. The functional significance of p53 activationmediated PRAME downregulation was demonstrated by measuring colony formation and p27 expression in melanoma cells. These data suggest that p53 activation, which leads to PRAME downregulation, could be a therapeutic strategy in melanoma cells. [BMB Reports 2024; 57(6): 299-304].

Rheumatoid arthritis (RA) is a systemic immune-mediated disease characterized by joint inflammation and destruction. The disease typically affects small joints in the hands and feet, later progressing to involve larger joints such as the knees, shoulders, and hips. While the reasons for these joint-specific differences are unclear, distinct epigenetic patterns associated with joint location have been reported. In this study, we evaluated the unique epigenetic landscapes of fibroblast-like synoviocytes (FLS) from hip and knee synovium in RA patients, focusing on the expression and regulation of Homeobox (HOX) transcription factors. These highly conserved genes play a critical role in embryonic development and are known to maintain distinct expression patterns in various adult tissues. We found that several HOX genes, especially HOXD10, were differentially expressed in knee FLS compared with hip FLS. Epigenetic differences in chromatin accessibility and histone marks were observed in HOXD10 promoter between knee and hip FLS. Histone modification, particularly histone acetylation, was identified as an important regulator of HOXD10 expression. To understand the mechanism of differential HOXD10 expression, we inhibited histone deacetylases (HDACs) with small molecules and siRNA. We found that HDAC1 blockade or deficiency normalized the joint-specific HOXD10 expression patterns. These observations suggest that epigenetic differences, specifically histone acetylation related to increased HDAC1 expression, play a crucial role in joint-specific HOXD10 expression. Understanding these mechanisms could provide insights into the regional aspects of RA and potentially lead to therapeutic strategies targeting specific patterns of joint involvement during the course of disease.

Dendritic cell (DC) progenitors adapt their transcriptional program during development, generating different subsets. How chromatin modifications modulate these processes is unclear. Here, we investigate the impact of histone deacetylation on DCs by genetically deleting histone deacetylase 1 (HDAC1) or HDAC2 in hematopoietic progenitors and CD11c-expressing cells. While HDAC2 is not critical for DC development, HDAC1 deletion impairs pro-pDC and mature pDC generation and affects ESAM+cDC2 differentiation from tDCs and pre-cDC2s, whereas cDC1s are unchanged. HDAC1 knockdown in human hematopoietic cells also impairs cDC2 development, highlighting its crucial role across species. Multi-omics analyses reveal that HDAC1 controls expression, chromatin accessibility, and histone acetylation of the transcription factors IRF4, IRF8, and SPIB required for efficient development of cDC2 subsets. Without HDAC1, DCs switch immunologically, enhancing tumor surveillance through increased cDC1 maturation and interleukin-12 production, driving T helper 1-mediated immunity and CD8+ T cell recruitment. Our study reveals the importance of histone acetylation in DC development and anti-tumor immunity, suggesting DC-targeted therapeutic strategies for immuno-oncology.

BACKGROUND: Intrahepatic cholangiocarcinoma (ICCA) is a heterogeneous group of malignant tumors characterized by high recurrence rate and poor prognosis. Heterochromatin Protein 1α (HP1α) is one of the most important nonhistone chromosomal proteins involved in transcriptional silencing via heterochromatin formation and structural maintenance. The effect of HP1α on the progression of ICCA remained unclear.
METHODS: The effect on the proliferation of ICCA was detected by experiments in two cell lines and two ICCA mouse models. The interaction between HP1α and Histone Deacetylase 1 (HDAC1) was determined using Electrospray Ionization Mass Spectrometry (ESI-MS) and the binding mechanism was studied using immunoprecipitation assays (co-IP). The target gene was screened out by RNA sequencing (RNA-seq). The occupation of DNA binding proteins and histone modifications were predicted by bioinformatic methods and evaluated by Cleavage Under Targets and Tagmentation (CUT & Tag) and Chromatin immunoprecipitation (ChIP).
RESULTS: HP1α was upregulated in intrahepatic cholangiocarcinoma (ICCA) tissues and regulated the proliferation of ICCA cells by inhibiting the interferon pathway in a Signal Transducer and Activator of Transcription 1 (STAT1)-dependent manner. Mechanistically, STAT1 is transcriptionally regulated by the HP1α-HDAC1 complex directly and epigenetically via promoter binding and changes in different histone modifications, as validated by high-throughput sequencing. Broad-spectrum HDAC inhibitor (HDACi) activates the interferon pathway and inhibits the proliferation of ICCA cells by downregulating HP1α and targeting the heterodimer. Broad-spectrum HDACi plus interferon preparation regimen was found to improve the antiproliferative effects and delay ICCA development in vivo and in vitro, which took advantage of basal activation as well as direct activation of the interferon pathway. HP1α participates in mediating the cellular resistance to both agents.
CONCLUSIONS: HP1α-HDAC1 complex influences interferon pathway activation by directly and epigenetically regulating STAT1 in transcriptional level. The broad-spectrum HDACi plus interferon preparation regimen inhibits ICCA development, providing feasible strategies for ICCA treatment. Targeting the HP1α-HDAC1-STAT1 axis is a possible strategy for treating ICCA, especially HP1α-positive cases.

Estrogen receptor-negative [ER(-)] mammary cancer is the most aggressive type of breast cancer (BC) with higher rate of metastasis and recurrence. In recent years, dietary prevention of BC with epigenetically active phytochemicals has received increased attention due to its feasibility, effectiveness, and ease of implementation. In this regard, combinatorial phytochemical intervention enables more efficacious BC inhibition by simultaneously targeting multiple tumorigenic pathways. We, therefore, focused on investigation of the effect of sulforaphane (SFN)-rich broccoli sprouts (BSp) and withaferin A (WA)-rich Ashwagandha (Ash) combination on BC prevention in estrogen receptor-negative [ER(-)] mammary cancer using transgenic mice. Our results indicated that combinatorial BSp + Ash treatment significantly reduced tumor incidence and tumor growth (~ 75%) as well as delayed (~ 21%) tumor latency when compared to the control treatment and combinatorial BSp + Ash treatment was statistically more effective in suppressing BC compared to single BSp or Ash intervention. At the molecular level, the BSp and Ash combination upregulated tumor suppressors (p53, p57) along with apoptosis associated proteins (BAX, PUMA) and BAX:BCL-2 ratio. Furthermore, our result indicated an expressional decline of epigenetic machinery HDAC1 and DNMT3A in mammary tumor tissue because of combinatorial treatment. Interestingly, we have reported multiple synergistic interactions between BSp and Ash that have impacted both tumor phenotype and molecular expression due to combinatorial BSp and Ash treatment. Our RNA-seq analysis results also demonstrated a transcriptome-wide expressional reshuffling of genes associated with multiple cell-signaling pathways, transcription factor activity and epigenetic regulations due to combined BSp and Ash administration. In addition, we discovered an alteration of gut microbial composition change because of combinatorial treatment. Overall, combinatorial BSp and Ash supplementation can prevent ER(-) BC through enhanced tumor suppression, apoptosis induction and transcriptome-wide reshuffling of gene expression possibly influencing multiple cell signaling pathways, epigenetic regulation and reshaping gut microbiota.

PA28γ overexpression is aberrant and accompanied by poor patient prognosis in various cancers, the precise regulatory mechanism of this crucial gene in the tumor microenvironment remains incompletely understood. In this study, using oral squamous cell carcinoma as a model, we demonstrated that PA28γ exhibits high expression in cancer-associated fibroblasts (CAFs), and its expression significantly correlates with the severity of clinical indicators of malignancy. Remarkably, we found that elevated levels of secreted IGF2 from PA28γ+ CAFs can enhance stemness maintenance and promote tumor cell aggressiveness through the activation of the MAPK/AKT pathway in a paracrine manner. Mechanistically, PA28γ upregulates IGF2 expression by stabilizing the E2F3 protein, a transcription factor of IGF2. Further mechanistic insights reveal that HDAC1 predominantly mediates the deacetylation and subsequent ubiquitination and degradation of E2F3. Notably, PA28γ interacts with HDAC1 and accelerates its degradation via a 20S proteasome-dependent pathway. Additionally, PA28γ+ CAFs exert an impact on the tumor immune microenvironment by secreting IGF2. Excitingly, our study suggests that targeting PA28γ+ CAFs or secreted IGF2 could increase the efficacy of PD-L1 therapy. Thus, our findings reveal the pivotal role of PA28γ in cell interactions in the tumor microenvironment and propose novel strategies for augmenting the effectiveness of immune checkpoint blockade in oral squamous cell carcinoma.

Plasmodium falciparum, the deadly protozoan parasite responsible for malaria, has a tightly regulated gene expression profile closely linked to its intraerythrocytic development cycle. Epigenetic modifiers of the histone acetylation code have been identified as key regulators of the parasite\'s transcriptome but require further investigation. In this study, we map the genomic distribution of Plasmodium falciparum histone deacetylase 1 (PfHDAC1) across the erythrocytic asexual development cycle and find it has a dynamic occupancy over a wide array of developmentally relevant genes. Overexpression of PfHDAC1 results in a progressive increment in parasite load over consecutive rounds of the asexual infection cycle and is associated with enhanced gene expression of multiple families of host cell invasion factors (merozoite surface proteins, rhoptry proteins, etc.) and with increased merozoite invasion efficiency. With the use of class-specific inhibitors, we demonstrate that PfHDAC1 activity in parasites is crucial for timely intraerythrocytic development. Interestingly, overexpression of PfHDAC1 results in decreased sensitivity to frontline-drug dihydroartemisinin in parasites. Furthermore, we identify that artemisinin exposure can interfere with PfHDAC1 abundance and chromatin occupancy, resulting in enrichment over genes implicated in response/resistance to artemisinin. Finally, we identify that dihydroartemisinin exposure can interrupt the in vitro catalytic deacetylase activity and post-translational phosphorylation of PfHDAC1, aspects that are crucial for its genomic function. Collectively, our results demonstrate PfHDAC1 to be a regulator of critical functions in asexual parasite development and host invasion, which is responsive to artemisinin exposure stress and deterministic of resistance to it.
OBJECTIVE: Malaria is a major public health problem, with the parasite Plasmodium falciparum causing most of the malaria-associated mortality. It is spread by the bite of infected mosquitoes and results in symptoms such as cyclic fever, chills, and headache. However, if left untreated, it can quickly progress to a more severe and life-threatening form. The World Health Organization currently recommends the use of artemisinin combination therapy, and it has worked as a gold standard for many years. Unfortunately, certain countries in southeast Asia and Africa, burdened with a high prevalence of malaria, have reported cases of drug-resistant infections. One of the major problems in controlling malaria is the emergence of artemisinin resistance. Population genomic studies have identified mutations in the Kelch13 gene as a molecular marker for artemisinin resistance. However, several reports thereafter indicated that Kelch13 is not the main mediator but rather hinted at transcriptional deregulation as a major determinant of drug resistance. Earlier, we identified PfGCN5 as a global regulator of stress-responsive genes, which are known to play a central role in artemisinin resistance generation. In this study, we have identified PfHDAC1, a histone deacetylase as a cell cycle regulator, playing an important role in artemisinin resistance generation. Taken together, our study identified key transcriptional regulators that play an important role in artemisinin resistance generation.