Lysine Acetylation/Deacetylation Modification of Immune-Related Molecules in Cancer Immunotherapy

Epigenetics of maternal-fetal interface immune microenvironment and placental related pregnancy complications

Epigenetic regulation of placental development and pregnancy-related disease processes has recently been a hot research topic. Implantation and subsequent placental development depend on carefully orchestrated interactions between fetal and maternal tissues, involving a delicate balance of immune factors. Epigenetic regulation, which refers to altering gene expression and function without changing the DNA sequence, is an essential regulatory process in cell biology. Several epigenetic modifications are known, such as DNA methylation, histone modifications, non-coding RNA regulation, and RNA methylation. Recently, there has been increasing evidence that epigenetic modifications are critical for the immune microenvironment at the maternal-fetal interface. In this review, we highlight recent advances in the role of epigenetics in the immune microenvironment at the maternal-fetal interface and in epigenetic regulation and placenta-associated pregnancy complications.

Trichostatin A augments cell migration and epithelial-mesenchymal transition in esophageal squamous cell carcinoma through BRD4/c-Myc endoplasmic reticulum-stress pathway

BACKGROUND

The causes of death in patients with advanced esophageal cancer are multifactorial, with tumor metastasis being one of the important factors. Histone acetylation promotes the migration of esophageal squamous cell carcinoma (ESCC) cells, while the histone deacetylase inhibitor (HDACi) shows complex effects on tumor functions.

AIM

To comprehensively elucidate the impact and molecular mechanisms of trichostatin A (TSA), an HDACi, on cell migration in ESCC through bromodomain-containing protein (BRD4)/cellular myelocytomatosis oncogene (c-Myc)/endoplasmic reticulum (ER)-stress.

METHODS

The effects of TSA on ESCC cell lines Eca109 and EC9706 migration were evaluated using Transwell assays, with small interfering transfection and pathway-specific inhibitors to elucidate underlying mechanisms. The mRNA levels involved were examined by quantitative real-time polymerase chain reaction. Protein levels of acetylated histones H3 (acH3) and acetylated histones H4, BRD4, c-Myc, as well as markers of ER stress and epithelial-mesenchymal transition (EMT), were analyzed using western blot. Additionally, this method was also used to examine acH3 levels in esophageal cancer tissues and adjacent tissues. Patient outcomes were subsequently tracked to identify prognostic indicators using Log-Rank tests and Cox multivariate analysis.

RESULTS

TSA promoted the migration of ESCC cells by stimulating the EMT process. TSA-mediated histone acetylation facilitated the recruitment of BRD4, a bromodomain-containing protein, triggering the expression of c-Myc. This cascade induced ER stress and enhanced EMT in ESCC cells. To further elucidate the underlying mechanism, we employed various interventions including the ER stress inhibitor 4-phenylbutyric acid, knockdown of c-Myc and BRD4 expression, and utilization of the BRD4 inhibitor carboxylic acid as well as the inhibitor of TSA 1. Mechanistically, these studies revealed that TSA-mediated histone acetylation facilitated the recruitment of BRD4, which in turn triggered the expression of c-Myc. This sequential activation induced ER stress and subsequently enhanced EMT, thereby promoting the migration of ESCC cells. Additionally, we examined histone acetylation levels in specimens from 43 patients with ESCC, including both tumor tissues and paired adjacent tissues. Statistical analysis unveiled a negative correlation between the level of histone acetylation and the long-term prognosis of patients with ESCC.

CONCLUSION

TSA promoted ESCC cell migration through the BRD4/c-Myc/ER stress pathway. Moreover, elevated histone acetylation in ESCC tissues correlated with poor ESCC prognosis. These findings enhance our understanding of ESCC migration and HDACi therapy.

HPV E6/E7-Induced Acetylation of a Peptide Encoded by a Long Non-Coding RNA Inhibits Ferroptosis to Promote the Malignancy of Cervical Cancer

Although a fraction of functional peptides concealed within long non-coding RNAs (lncRNAs) is identified, it remains unclear whether lncRNA-encoded peptides are involved in the malignancy of cervical cancer (CC). Here, a 92-amino acid peptide is discovered, which is named TUBORF, encoded by lncRNA TUBA3FP and highly expressed in CC tissues. TUBORF inhibits ferroptosis to promote the malignant proliferation of CC cells. Mechanistically, human papillomavirus (HPV) oncogenes E6 and E7 upregulate TUBORF through CREB-binding protein (CBP)/E1A-binding protein p300 (p300)-mediated histone H3 lysine 27 acetylation (H3K27ac) of lncTUBA3FP enhancer. Furthermore, E6 and E7 elevate and recruit acetyltransferase establishment of sister chromatid cohesion N-acetyltransferase 1 (ESCO1) to bind to and acetylate TUBORF, which facilitates the degradation of immunity-related GTPase Q (IRGQ) via a ubiquitin-proteasome pathway, resulting in the inhibition of ferroptosis and promotion of the malignant proliferation of CC cells. Importantly, silencing ESCO1 or TURORF amplifies anticancer effects by paclitaxel both in CC cells and in vivo. These novel findings reveal oncopeptide TUBORF and its acetyltransferase ESCO1 as important regulators of ferroptosis and tumorigenesis during cervical cancer pathogenesis and establish the scientific basis for targeting these molecules for treating CC.

Genome-Wide Identification and Characterization of Histone Acetyltransferases and Deacetylases in Cucumber, and Their Implication in Developmental Processes

BACKGROUND/OBJECTIVES

Cucumber (Cucumis sativus) provides a model for exploring the molecular basis of sex determination, particularly the regulation of floral organ differentiation through gene expression. This complex process is modulated by epigenetic factors, such as histone acetyltransferases (HATs) and histone deacetylases (HDACs), which respectively activate and repress gene transcription by adding or removing acetyl groups from histone proteins. Despite their known functions, the roles of HATs and HDACs throughout cucumber's floral developmental stages remain unclear.

METHODS

In this study, we conducted a genome-wide analysis of HAT and HDAC gene families in cucumber, examining their phylogenetic relationships, gene structures, protein domains, and expression profiles across various stages of floral development.

RESULTS

We identified 36 CsHAT and 12 CsHDAC genes, grouping them into families with evolutionary counterparts in other plant species. RNA sequencing revealed stage-specific expression patterns, suggesting dynamic roles for these gene families in floral organ development.

CONCLUSIONS

These findings contribute valuable insights into the epigenetic regulation of gene expression in cucumber flower formation, presenting avenues for further research on the genetic control of plant reproductive development.

Post-translational modifications and bronchopulmonary dysplasia

Bronchopulmonary dysplasia is a prevalent respiratory disorder posing a significant threat to the quality of life in premature infants. Its pathogenesis is intricate, and therapeutic options are limited. Besides genetic coding, protein post-translational modification plays a pivotal role in regulating cellular function, contributing complexity and diversity to substrate proteins and influencing various cellular processes. Substantial evidence indicates that post-translational modifications of several substrate proteins are intricately related to the molecular mechanisms underlying bronchopulmonary dysplasia. These modifications facilitate the progression of bronchopulmonary dysplasia through a cascade of signal transduction events. This review outlines the relationships between substrate protein phosphorylation, acetylation, ubiquitination, SUMOylation, methylation, glycosylation, glycation, S-glutathionylation, S-nitrosylation and bronchopulmonary dysplasia. The aim is to provide novel insights into bronchopulmonary dysplasia's pathogenesis and potential therapeutic targets for clinical management.

Epigenetic modifications involving ncRNAs in digestive system cancers: focus on histone modification

In recent years, epigenetic modifications have been strongly linked to tumor development, with histone modifications representing a key epigenetic mechanism. In addition, non-coding RNAs (ncRNAs) play a critical role in regulating cancer-related pathways. The abnormal interaction between histone modifications and ncRNAs, both pivotal epigenetic regulators, has been widely observed across various cancer types. Here, we systematically explore the molecular mechanisms through which histone modifications and ncRNAs contribute in the pathogenesis of digestive system cancers, and aberrant ncRNA-mediated histone modifications manipulate various biological behaviors of tumor cells including proliferation, migration, angiogenesis, etc. In addition, we provide new insights into diagnostic, prognostic markers, therapeutic targets and chemoradiation resistance for digestive system cancers from the epigenetic perspective.

Histone deacetylases: Regulation of vascular homeostasis via endothelial cells and vascular smooth muscle cells and the role in vascular pathogenesis

Histone deacetylases (HDACs) are proteases that play a key role in chromosome structural modification and gene expression regulation, and the involvement of HDACs in cancer, the nervous system, and the metabolic and immune system has been well reviewed. Our understanding of the function of HDACs in the vascular system has recently progressed, and a significant variety of HDAC inhibitors have been shown to be effective in the treatment of vascular diseases. However, few reviews have focused on the role of HDACs in the vascular system. In this study, the role of HDACs in the regulation of the vascular system mainly involving endothelial cells and vascular smooth muscle cells was discussed based on recent updates, and the role of HDACs in different vascular pathogenesis was summarized as well. Furthermore, the therapeutic effects and prospects of HDAC inhibitors were also addressed in this review.

Dysregulation of lysine acetylation in the pathogenesis of digestive tract cancers and its clinical applications

Recent advances in high-resolution mass spectrometry-based proteomics have improved our understanding of lysine acetylation in proteins, including histones and non-histone proteins. Lysine acetylation, a reversible post-translational modification, is catalyzed by lysine acetyltransferases (KATs) and lysine deacetylases (KDACs). Proteins comprising evolutionarily conserved bromodomains (BRDs) recognize these acetylated lysine residues and consequently activate transcription. Lysine acetylation regulates almost all cellular processes, including transcription, cell cycle progression, and metabolic functions. Studies have reported the aberrant expression, translocation, and mutation of genes encoding lysine acetylation regulators in various cancers, including digestive tract cancers. These dysregulated lysine acetylation regulators contribute to the pathogenesis of digestive system cancers by modulating the expression and activity of cancer-related genes or pathways. Several inhibitors targeting KATs, KDACs, and BRDs are currently in preclinical trials and have demonstrated anti-cancer effects. Digestive tract cancers, including encompass esophageal, gastric, colorectal, liver, and pancreatic cancers, represent a group of heterogeneous malignancies. However, these cancers are typically diagnosed at an advanced stage owing to the lack of early symptoms and are consequently associated with poor 5-year survival rates. Thus, there is an urgent need to identify novel biomarkers for early detection, as well as to accurately predict the clinical outcomes and identify effective therapeutic targets for these malignancies. Although the role of lysine acetylation in digestive tract cancers remains unclear, further analysis could improve our understanding of its role in the pathogenesis of digestive tract cancers. This review aims to summarize the implications and pathogenic mechanisms of lysine acetylation dysregulation in digestive tract cancers, as well as its potential clinical applications.

Lysine lactylation in the regulation of tumor biology

Lysine lactylation (Kla), a newly discovered post-translational modification (PTM) of lysine residues, is progressively revealing its crucial role in tumor biology. A growing body of evidence supports its capacity of transcriptional regulation through histone modification and modulation of non-histone protein function. It intricately participates in a myriad of events in the tumor microenvironment (TME) by orchestrating the transitions of immune states and augmenting tumor malignancy. Its preferential modification of metabolic proteins underscores its specific regulatory influence on metabolism. This review focuses on the effect and the probable mechanisms of Kla-mediated regulation of tumor metabolism, the upstream factors that determine Kla intensity, and its potential implications for the clinical diagnosis and treatment of tumors.

Unravelling infiltrating T-cell heterogeneity in kidney renal clear cell carcinoma: Integrative single-cell and spatial transcriptomic profiling

Kidney renal clear cell carcinoma (KIRC) pathogenesis intricately involves immune system dynamics, particularly the role of T cells within the tumour microenvironment. Through a multifaceted approach encompassing single-cell RNA sequencing, spatial transcriptome analysis and bulk transcriptome profiling, we systematically explored the contribution of infiltrating T cells to KIRC heterogeneity. Employing high-density weighted gene co-expression network analysis (hdWGCNA), module scoring and machine learning, we identified a distinct signature of infiltrating T cell-associated genes (ITSGs). Spatial transcriptomic data were analysed using robust cell type decomposition (RCTD) to uncover spatial interactions. Further analyses included enrichment assessments, immune infiltration evaluations and drug susceptibility predictions. Experimental validation involved PCR experiments, CCK-8 assays, plate cloning assays, wound-healing assays and Transwell assays. Six subpopulations of infiltrating and proliferating T cells were identified in KIRC, with notable dynamics observed in mid- to late-stage disease progression. Spatial analysis revealed significant correlations between T cells and epithelial cells across varying distances within the tumour microenvironment. The ITSG-based prognostic model demonstrated robust predictive capabilities, implicating these genes in immune modulation and metabolic pathways and offering prognostic insights into drug sensitivity for 12 KIRC treatment agents. Experimental validation underscored the functional relevance of PPIB in KIRC cell proliferation, invasion and migration. Our study comprehensively characterizes infiltrating T-cell heterogeneity in KIRC using single-cell RNA sequencing and spatial transcriptome data. The stable prognostic model based on ITSGs unveils infiltrating T cells' prognostic potential, shedding light on the immune microenvironment and offering avenues for personalized treatment and immunotherapy.

Converting "cold" to "hot": epigenetics strategies to improve immune therapy effect by regulating tumor-associated immune suppressive cells

Significant developments in cancer treatment have been made since the advent of immune therapies. However, there are still some patients with malignant tumors who do not benefit from immunotherapy. Tumors without immunogenicity are called "cold" tumors which are unresponsive to immunotherapy, and the opposite are "hot" tumors. Immune suppressive cells (ISCs) refer to cells which can inhibit the immune response such as tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), regulatory T (Treg) cells and so on. The more ISCs infiltrated, the weaker the immunogenicity of the tumor, showing the characteristics of "cold" tumor. The dysfunction of ISCs in the tumor microenvironment (TME) may play essential roles in insensitive therapeutic reaction. Previous studies have found that epigenetic mechanisms play an important role in the regulation of ISCs. Regulating ISCs may be a new approach to transforming "cold" tumors into "hot" tumors. Here, we focused on the function of ISCs in the TME and discussed how epigenetics is involved in regulating ISCs. In addition, we summarized the mechanisms by which the epigenetic drugs convert immunotherapy-insensitive tumors into immunotherapy-sensitive tumors which would be an innovative tendency for future immunotherapy in "cold" tumor.

Lactylproteome analysis indicates histone H4K12 lactylation as a novel biomarker in triple-negative breast cancer

Objective

The established link between posttranslational modifications of histone and non-histone lysine (K) residues in cell metabolism, and their role in cancer progression, is well-documented. However, the lactylation expression signature in triple-negative breast cancer (TNBC) remains underexplored.

Methods

We conducted a comprehensive lactylproteome profiling of eight pairs of TNBC samples and their matched adjacent tissues. This was achieved through 4-Dimensional label-free quantitative proteomics combined with lactylation analysis (4D-LFQP-LA). The expression of identified lactylated proteins in TNBC was detected using immunoblotting and immunohistochemistry (IHC) with specific primary antibodies, and their clinicopathological and prognostic significance was evaluated.

Results

Our analysis identified 58 lactylation sites on 48 proteins, delineating the protein lactylation alteration signature in TNBC. Bioinformatic and functional analyses indicated that these lactylated proteins play crucial roles in regulating key biological processes in TNBC. Notably, lactylation of lysine at position 12 (H4K12lac) in the histone H4 domain was found to be upregulated in TNBC. Further investigations showed a high prevalence of H4K12lac upregulation in TNBC, with positive rates of 93.19% (137/147) and 92.93% (92/99) in TNBC tissue chip and validation cohorts, respectively. H4K12lac expression correlated positively with Ki-67 and inversely with overall survival (OS) in TNBC (HR [hazard ratio] =2.813, 95%CI [credibility interval]: 1.242-6.371, P=0.0164), suggesting its potential as an independent prognostic marker (HR=3.477, 95%CI: 1.324-9.130, P=0.011).

Conclusions

Lactylation is a significant post-translational modification in TNBC proteins. H4K12lac emerges as a promising biomarker for TNBC, offering insights into the lactylation profiles of TNBC proteins and linking histone modifications to clinical implications in TNBC.

Molecular subgroup establishment and signature creation of lncRNAs associated with acetylation in lung adenocarcinoma

BACKGROUND

The significance of long non-coding RNAs (lncRNAs) as pivotal mediators of histone acetylation and their influential role in predicting the prognosis of lung adenocarcinoma (LUAD) has been increasingly recognized. However, there remains uncertainty regarding the potential utility of acetylation-related lncRNAs (ARLs) in prognosticating the overall survival (OS) of LUAD specimens.

METHODS

The RNA-Seq and clinical information were downloaded from The Cancer Genome Atlas (TCGA). Through the differential analysis, weighted correlation network analysis (WGCNA), Pearson correlation test and univariate Cox regression, we found out the prognosis associated ARLs and divided LUAD specimens into two molecular subclasses. The ARLs were employed to construct a unique signature through the implementation of the Least Absolute Shrinkage and Selection Operator (LASSO) algorithm. Subsequently, the predictive performance was evaluated using ROC analysis and Kaplan-Meier survival curve analysis. Finally, ARL expression in LUAD was confirmed by quantitative real-time PCR (qRT-PCR).

RESULTS

We triumphantly built a ARLs prognostic model with excellent predictive accuracy for LUAD. Univariate and multivariate Cox analysis illustrated that risk model served as an independent predictor for influencing the overall survival OS of LUAD. Furthermore, a nomogram exhibited strong prognostic validity. Additionally, variations were observed among subgroups in the field of immunity, biological functions, drug sensitivity and gene mutations within the field.

CONCLUSIONS

Nine ARLs were identified as promising indicators of personalized prognosis and drug selection for people suffering with LUAD.

Emerging Neuroprotective Strategies: Unraveling the Potential of HDAC Inhibitors in Traumatic Brain Injury Management

Traumatic brain injury (TBI) is a significant global health problem, leading to high rates of mortality and disability. It occurs when an external force damages the brain, causing immediate harm and triggering further pathological processes that exacerbate the condition. Despite its widespread impact, the underlying mechanisms of TBI remain poorly understood, and there are no specific pharmacological treatments available. This creates an urgent need for new, effective neuroprotective drugs and strategies tailored to the diverse needs of TBI patients. In the realm of gene expression regulation, chromatin acetylation plays a pivotal role. This process is controlled by two classes of enzymes: histone acetyltransferase (HAT) and histone deacetylase (HDAC). These enzymes modify lysine residues on histone proteins, thereby determining the acetylation status of chromatin. HDACs, in particular, are involved in the epigenetic regulation of gene expression in TBI. Recent research has highlighted the potential of HDAC inhibitors (HDACIs) as promising neuroprotective agents. These compounds have shown encouraging results in animal models of various neurodegenerative diseases. HDACIs offer multiple avenues for TBI management: they mitigate the neuroinflammatory response, alleviate oxidative stress, inhibit neuronal apoptosis, and promote neurogenesis and axonal regeneration. Additionally, they reduce glial activation, which is associated with TBI-induced neuroinflammation. This review aims to provide a comprehensive overview of the roles and mechanisms of HDACs in TBI and to evaluate the therapeutic potential of HDACIs. By summarizing current knowledge and emphasizing the neuroregenerative capabilities of HDACIs, this review seeks to advance TBI management and contribute to the development of targeted treatments.

Grass carp (Ctenopharyngodon idella) deacetylase SIRT1 targets p53 to suppress apoptosis in a KAT8 dependent or independent manner

Sirtuin1 (SIRT1) is known as a deacetylase to control various physiological processes. In mammals, SIRT1 inhibits apoptotic process, but the detailed mechanism is not very clear. Here, our study revealed that grass carp (Ctenopharyngodon idella) SIRT1 (CiSIRT1, MN125614.1) inhibits apoptosis through targeting p53 in a KAT8-dependent or a KAT8-independent manner. In CIK cells, CiSIRT1 over-expression results in significant decrease of some apoptotic gene expressions, including Bax/Bcl2, caspase3 and caspase9, whereas CiKAT8 or Cip53 facilitates the induction of apoptosis. Because CiSIRT1 separately interacted with CiKAT8 and Cip53, we speculated that CiSIRT1 blocked apoptosis may be by virtue of KAT8-p53 axis or directly by p53. In a KAT8-dependent manner, CiSIRT1 interacted with CiKAT8, then reduced the acetylation of CiKAT8 and subsequently promoted its degradation. Then, CiKAT8 acetylated p53 and induced p53-mediated apoptosis. MYST domain of CiKAT8 was critical in this pathway. In a KAT8-independent manner, CiSIRT1 also inhibited p53-induced apoptosis by directly deacetylating p53 and promoting the degradation of p53. Generally, these findings uncovered two pathways in which CiSIRT1 decreases the acetylation of p53 via a KAT8-dependent or a KAT8-independent manner.

Hepatic safety profile of pancreatic cancer‑bearing mice fed a ketogenic diet in combination with gemcitabine

Ketogenic diets (KDs) are actively being evaluated for their potential anticancer effects. Although KDs are generally considered safe, their safety profile when combined with chemotherapy remains unknown. It is known that a KD enhances the anticancer effect of gemcitabine (2',2'-difluoro-2'-deoxycytidine) in LSL-KrasLSL-G12D/+Trp53R172H/+Pdx-1-Cre (KPC) tumor-bearing mice. In the present study, whether a KD in combination with gemcitabine affected the liver safety profile in KPC mice was evaluated. For this purpose, male and female pancreatic tumor-bearing KPC mice were allocated to a control diet (CD; % kcal: 20% fat, 65% carbohydrate, 15% protein) + gemcitabine [control plus gemcitabine group (CG)] or a KD (% kcal: 84% fat, 15% protein, 1% carbohydrate) + gemcitabine [ketogenic plus gemcitabine group (KG)] for two months. After two months of treatment, no significant differences in body weight were observed between CGs and KGs. Moreover, the KD did not significantly alter the serum protein expression levels of liver enzymes, including aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase. In addition, the KD did not alter markers of liver-lipid accumulation as well as serum cholesterol and triglyceride levels, compared with the CG-treated group. Upon histologic examination, steatosis was rare, with no notable differences between treatment groups. When examining liver fatty acid composition, KD treatment significantly increased the content of saturated fatty acids and significantly decreased levels of cis-monounsaturated fatty acids compared with the CG. Finally, the KD did not affect liver markers of inflammation and oxidative stress, nor the protein expression levels of enzymes involved in ketone bodies, such as 3-hydroxy-3-methylglutaryl-CoA lyase and hidroximetilglutaril-CoA sintasa, and glucose metabolism, such as hexokinase 2, pyruvate dehydrogenase and phosphofructokinase. In summary, a KD in combination with gemcitabine appears to be safe, with no apparent hepatotoxicity and these data support the further evaluation of a KD as an adjuvant dietary treatment for pancreatic cancer.

Integrative analysis of lysine acetylation-related genes and identification of a novel prognostic model for oral squamous cell carcinoma

Introduction: Oral squamous cell carcinoma (OSCC), which accounts for a high proportion of oral cancers, is characterized by high aggressiveness and rising incidence. Lysine acetylation is associated with cancer pathogenesis. Lysine acetylation-related genes (LARGs) are therapeutic targets and potential prognostic indicators in various tumors, including oral squamous cell carcinoma. However, systematic bioinformatics analysis of the Lysine acetylation-related genes in Oral squamous cell carcinoma is still unexplored. Methods: We analyzed the expression of 33 Lysine acetylation-related genes in oral squamous cell carcinoma and the effects of their somatic mutations on oral squamous cell carcinoma prognosis. Consistent clustering analysis identified two lysine acetylation patterns and the differences between the two patterns were further evaluated. Least absolute shrinkage and selection operator (LASSO) regression analysis was used to develop a lysine acetylation-related prognostic model using TCGA oral squamous cell carcinoma datasets, which was then validated using gene expression omnibus (GEO) dataset GSE41613. Results: Patients with lower risk scores had better prognoses, in both the overall cohort and within the subgroups These patients also had "hot" immune microenvironments and were more sensitive to immunotherapy. Disscussion: Our findings offer a new model for classifying oral squamous cell carcinoma and determining its prognosis and offer novel insights into oral squamous cell carcinoma diagnosis and treatment.

Post-translational modifications and immune responses in liver cancer

Post-translational modification (PTM) refers to the covalent attachment of functional groups to protein substrates, resulting in structural and functional changes. PTMs not only regulate the development and progression of liver cancer, but also play a crucial role in the immune response against cancer. Cancer immunity encompasses the combined efforts of innate and adaptive immune surveillance against tumor antigens, tumor cells, and tumorigenic microenvironments. Increasing evidence suggests that immunotherapies, which harness the immune system's potential to combat cancer, can effectively improve cancer patient prognosis and prolong the survival. This review presents a comprehensive summary of the current understanding of key PTMs such as phosphorylation, ubiquitination, SUMOylation, and glycosylation in the context of immune cancer surveillance against liver cancer. Additionally, it highlights potential targets associated with these modifications to enhance the response to immunotherapies in the treatment of liver cancer.

Post-translational modifications of histones: Mechanisms, biological functions, and therapeutic targets

Histones are DNA-binding basic proteins found in chromosomes. After the histone translation, its amino tail undergoes various modifications, such as methylation, acetylation, phosphorylation, ubiquitination, malonylation, propionylation, butyrylation, crotonylation, and lactylation, which together constitute the "histone code." The relationship between their combination and biological function can be used as an important epigenetic marker. Methylation and demethylation of the same histone residue, acetylation and deacetylation, phosphorylation and dephosphorylation, and even methylation and acetylation between different histone residues cooperate or antagonize with each other, forming a complex network. Histone-modifying enzymes, which cause numerous histone codes, have become a hot topic in the research on cancer therapeutic targets. Therefore, a thorough understanding of the role of histone post-translational modifications (PTMs) in cell life activities is very important for preventing and treating human diseases. In this review, several most thoroughly studied and newly discovered histone PTMs are introduced. Furthermore, we focus on the histone-modifying enzymes with carcinogenic potential, their abnormal modification sites in various tumors, and multiple essential molecular regulation mechanism. Finally, we summarize the missing areas of the current research and point out the direction of future research. We hope to provide a comprehensive understanding and promote further research in this field.

The inhibitory effect and mechanism of small molecules on acetic anhydride-induced BSA acetylation and aggregation

Protein acetylation is a significant post-translational modification, and hyperacetylation results in amyloid aggregation, which is closely related to neurodegenerative diseases (Alzheimer's disease, Huntington's disease, and so on). Therefore, it is significant to inhibit the hyperacetylation of proteins and their induced aggregation. In the present study, we aimed to explore the anti-acetylation and anti-amyloid properties of five small molecules (gallic acid, menadione, resveratrol, apigenin, and quercetin) in the process of acetic anhydride-induced protein hyperacetylation and its aggregation. Optical detection methods, such as SDS-PAGE, inverted fluorescence microscopy, and endogenous fluorescence spectroscopy, were used to investigate the effects of small molecules on protein acetylation, aggregation, and structure. In addition, fluorescence quenching and molecular docking techniques were used to explore the relationship between small molecules and acetylation. The results showed that gallic acid (200 μM), menadione (100 μM), quercetin (40 μM), resveratrol (5 μM), and apigenin (20 μM) (unmodified rates were 61.12 %, 67.76 %, 65.11 %, 62.66 %, and 67.81 %, respectively) had strong inhibitory effects on acetylation, and there was no significant difference (P < 0.05). In addition, gallic acid (200 μM), menadione (100 μM), and resveratrol (5 μM) (inhibition rates of 29.89 %, 26.53 %, and 26.09 %, respectively) had more substantial inhibitory effects on protein aggregation, indicating that the five small molecules could inhibit acetic anhydride-induced hyperacetylation and protein aggregation. The underlying mechanism might be that it could inhibit hyperacetylation and resist amyloid aggregation by interacting with proteins to occupy acetylation sites. Collectively, our findings showed that gallic acid, menadione, and resveratrol could potentially prevent and treat neurodegenerative diseases, such as Alzheimer's disease, by inhibiting acetylation and acetylation-induced aggregation.

Targeting epigenetic regulators to overcome drug resistance in cancers

Drug resistance is mainly responsible for cancer recurrence and poor prognosis. Epigenetic regulation is a heritable change in gene expressions independent of nucleotide sequence changes. As the common epigenetic regulation mechanisms, DNA methylation, histone modification, and non-coding RNA regulation have been well studied. Increasing evidence has shown that aberrant epigenetic regulations contribute to tumor resistance. Therefore, targeting epigenetic regulators represents an effective strategy to reverse drug resistance. In this review, we mainly summarize the roles of epigenetic regulation in tumor resistance. In addition, as the essential factors for epigenetic modifications, histone demethylases mediate the histone or genomic DNA modifications. Herein, we comprehensively describe the functions of the histone demethylase family including the lysine-specific demethylase family, the Jumonji C-domain-containing demethylase family, and the histone arginine demethylase family, and fully discuss their regulatory mechanisms related to cancer drug resistance. In addition, therapeutic strategies, including small-molecule inhibitors and small interfering RNA targeting histone demethylases to overcome drug resistance, are also described.

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

Bone marrow transplantation is regarded as the most effective immunotherapy for hematologic cancer, but it generally faces difficulties in matching. Aberrant expression of histone deacetylases (HDACs) is closely related to the occurrence and development of hematological cancer. Recent studies suggested that HDACs might play a critical role in initiating anti-cancer immune response or enhancing anti-cancer immunotherapy. Besides, combining HDAC inhibition and immunotherapy could prevent immunotherapy resistance in some degree and reach an extended treatment window. This review summarized the relationship between HDACs and immune and described the current understanding of HDACs in immunotherapy for hematologic cancer.

Deciphering Regulatory Proteins of Prenylated Protein via the FRET Technique Using Nitroso-Based Ene-Ligation and Sequential Azidation and Click Reaction

We report here the selective incorporations of nitroso species into a wide range of proteins targeting lysine residue(s). The corresponding azo functionalities were formed in a highly selective manner with excellent yields, displaying rather good stability under physiological conditions. Furthermore, the azodation proceeded smoothly in high yields on targeted peptides. Fluorescent and/or dual fluorescent labeling of varied proteins following this protocol have been determined efficiently and selectively. With this established protocol, we aim to determine its usage in the evaluation of the interaction of prenylated proteins with their interacted enzyme(s) via FRET assays. Delightedly, chemically modified proteins with a 1-pyrenyl fluorophore through 254 nm UV irradiation and the sequential azodation and click reaction of protein prenyl functionality, which enable the incorporation of naphthene, indeed increase the fluorescence energy transferred since we observed significantly enhanced absorption located at 218 nm in lysed HEK293T cells and a clearly strengthened greenish fluorescence in living HEK293T cells.