Role of histone acetylation in gastric cancer: implications of dietetic compounds and clinical perspectives

An Overview of the Spices Used for the Prevention and Potential Treatment of Gastric Cancer

Gastric cancer (GC) ranks third in terms of cancer-related deaths and is the fifth most commonly diagnosed type of cancer. Its risk factors include Helicobacter pylori infection, Epstein-Barr virus infection, the consumption of broiled and charbroiled animal meats, salt-preserved and smoke-enhanced foods, alcohol drinking, tobacco smoking, exposure to ionizing radiation, and positive family history. The limited effectiveness of conventional therapies and the widespread risk factors of GC encourage the search for new methods of treatment and prevention. In the quest for cheap and commonly available medications, numerous studies focus on herbal medicine, traditional brews, and spices. In this review, we outline the potential use of spices, including turmeric, ginger, garlic, black cumin, chili pepper, saffron, black pepper, rosemary, galangal, coriander, wasabi, cinnamon, oregano, cardamom, fenugreek, caraway, clove, dill, thyme, Piper sarmentosum, basil, as well as the compounds they contain, in the prevention and treatment of GC. We present the potential molecular mechanisms responsible for the effectivity of a given seasoning substance and their impact on GC cells. We discuss their potential effects on proliferation, apoptosis, and migration. For most of the spices discussed, we also outline the unavailability and side effects of their use.

Systematic analysis of histone acetylation regulators across human cancers

BACKGROUND

Histone acetylation (HA) is an important and common epigenetic pathway, which could be hijacked by tumor cells during carcinogenesis and cancer progression. However, the important role of HA across human cancers remains elusive.

METHODS

In this study, we performed a comprehensive analysis at multiple levels, aiming to systematically describe the molecular characteristics and clinical relevance of HA regulators in more than 10000 tumor samples representing 33 cancer types.

RESULTS

We found a highly heterogeneous genetic alteration landscape of HA regulators across different human cancer types. CNV alteration may be one of the major mechanisms leading to the expression perturbations in HA regulators. Furthermore, expression perturbations of HA regulators correlated with the activity of multiple hallmark oncogenic pathways. HA regulators were found to be potentially useful for the prognostic stratification of kidney renal clear cell carcinoma (KIRC). Additionally, we identified HDAC3 as a potential oncogene in lung adenocarcinoma (LUAD).

CONCLUSION

Overall, our results highlights the importance of HA regulators in cancer development, which may contribute to the development of clinical strategies for cancer treatment.

Molecular mechanisms underlying the clinical efficacy of panobinostat involve Stochasticity of epigenetic signaling, sensitization to anticancer drugs, and induction of cellular cell death related to cellular stresses

Panobinostat, also known as Farydak®, LBH589, PNB, or panobinostat lactate, is a hydroxamic acid that has been approved by the Food and Drug Administration (FDA) for its anti-cancer properties. This orally bioavailable drug is classified as a non-selective histone deacetylase inhibitor (pan-HDACi) that inhibits class I, II, and IV HDACs at nanomolar levels due to its significant histone modifications and epigenetic mechanisms. A mismatch between histone acetyltransferases (HATs) and HDACs can negatively affect the regulation of the genes concerned, which in turn can contribute to tumorigenesis. Indeed, panobinostat inhibits HDACs, potentially leading to acetylated histone accumulation, re-establishing normal gene expression in cancer cells, and helping to drive multiple signaling pathways. These pathways include induction of histone acetylation and cytotoxicity for the majority of tested cancer cell lines, increased levels of p21 cell cycle proteins, enhanced amounts of pro-apoptotic factors (such as caspase-3/7 activity and cleaved poly (ADP-ribose) polymerase (PARP)) associated with decreased levels of anti-apoptotic factors [B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra-large (Bcl-XL)], as well as regulation of immune response [upregulated programmed death-ligand 1 (PD-L1) and interferon gamma receptor 1 (IFN-γR1) expression] and other events. The therapeutic outcome of panobinostat is therefore mediated by sub-pathways involving proteasome and/or aggresome degradation, endoplasmic reticulum, cell cycle arrest, promotion of extrinsic and intrinsic processes of apoptosis, tumor microenvironment remodeling, and angiogenesis inhibition. In this investigation, we aimed to pinpoint the precise molecular mechanism underlying panobinostat's HDAC inhibitory effect. A more thorough understanding of these mechanisms will greatly advance our knowledge of cancer cell aberrations and, as a result, provide an opportunity for the discovery of significant new therapeutic perspectives through cancer therapeutics.

Post-Translational Modifications in Tumor-Associated Antigens as a Platform for Novel Immuno-Oncology Therapies

Post-translational modifications (PTMs) are generated by adding small chemical groups to amino acid residues after the translation of proteins. Many PTMs have been reported to correlate with tumor progression, growth, and survival by modifying the normal functions of the protein in tumor cells. PTMs can also elicit humoral and cellular immune responses, making them attractive targets for cancer immunotherapy. This review will discuss how the acetylation, citrullination, and phosphorylation of proteins expressed by tumor cells render the corresponding tumor-associated antigen more antigenic and affect the immune response in multiple cancers. In addition, the role of glycosylated protein mucins in anti-cancer immunotherapy will be considered. Mucin peptides in combination with stimulating adjuvants have, in fact, been utilized to produce anti-tumor antibodies and vaccines. Finally, we will also outline the results of the clinical trial exploiting glycosylated-MUC1 as a vaccine in different cancers. Overall, PTMs in TAAs could be considered in future therapies to result in lasting anti-tumor responses.

The landscape of histone modifications in epigenomics since 2020

Histone proteins are a primary component of chromatin; therefore, any modifications to their structure are anticipated to affect the behavior of our genetic material, which is manifested in the form of phenotypic changes at a molecular, cellular or organic level. The majority of histone modifications are of either methylation or acetylation type that regulate gene expression. Though, not all of these modifications are concerned with the direct regulation of gene transcription. Throughout its 13-year run, Epigenomics has never ceased to cover these most gripping epigenetic stories, a significant proportion of which is in the matter of histones and their modifications. As such, the current perspective piece is intended to highlight original histone-oriented contributions published in Epigenomics since 2020.

Systems biology and OMIC data integration to understand gastrointestinal cancers

Gastrointestinal (GI) cancers are a set of diverse diseases affecting many parts/ organs. The five most frequent GI cancer types are esophageal, gastric cancer (GC), liver cancer, pancreatic cancer, and colorectal cancer (CRC); together, they give rise to 5 million new cases and cause the death of 3.5 million people annually. We provide information about molecular changes crucial to tumorigenesis and the behavior and prognosis. During the formation of cancer cells, the genomic changes are microsatellite instability with multiple chromosomal arrangements in GC and CRC. The genomically stable subtype is observed in GC and pancreatic cancer. Besides these genomic subtypes, CRC has epigenetic modification (hypermethylation) associated with a poor prognosis. The pathway information highlights the functions shared by GI cancers such as apoptosis; focal adhesion; and the p21-activated kinase, phosphoinositide 3-kinase/Akt, transforming growth factor beta, and Toll-like receptor signaling pathways. These pathways show survival, cell proliferation, and cell motility. In addition, the immune response and inflammation are also essential elements in the shared functions. We also retrieved information on protein-protein interaction from the STRING database, and found that proteins Akt1, catenin beta 1 (CTNNB1), E1A binding protein P300, tumor protein p53 (TP53), and TP53 binding protein 1 (TP53BP1) are central nodes in the network. The protein expression of these genes is associated with overall survival in some GI cancers. The low TP53BP1 expression in CRC, high EP300 expression in esophageal cancer, and increased expression of Akt1/TP53 or low CTNNB1 expression in GC are associated with a poor prognosis. The Kaplan Meier plotter database also confirmed the association between expression of the five central genes and GC survival rates. In conclusion, GI cancers are very diverse at the molecular level. However, the shared mutations and protein pathways might be used to understand better and reveal diagnostic/prognostic or drug targets.

The emerging double-edged sword role of Sirtuins in the gastric inflammation-carcinoma sequence revealed by bulk and single-cell transcriptomes

Histone modification and the inflammation-carcinoma sequence (ICS) have been acknowledgedly implicated in gastric carcinogenesis. However, the extremum expression of some histone modification genes (HMGs) in intestinal metaplasia (IM) rather than GC obscures the roles of HMGs in ICS. In this study, we assumed an explanation that the roles of HMGs in ICS were stage specific. Bulk RNA-seq on endoscopy biopsy samples from a total of 50 patients was accompanied by reanalysis of a set of published single-cell transcriptomes, which cross-sectionally profiled the transcriptomic features of chronic superficial gastritis (SG), atrophy gastritis (AG), IM, and early gastric cancer (GC). Differential analysis observed significantly peaked expression of SIRT6 and SIRT7 at IM. Weighted correlation network analysis on bulk transcriptome recognized significant correlations between SIRT1/6 and IM. The single-cell atlas identified one subgroup of B cells expressing high level of TFF1 (TFF1^hi naive B cell) that theoretically played important roles in defending microbial infection, while SIRT6 displayed a positive correlation with TFF1^low naive B cells. Moreover, gene set enrichment analysis at different lesions (SG-AG, AG-IM, and IM-GC) highlighted that gene sets contributing to IM, e.g., Brush Border, were largely enriched from co-expressing genes of Sirtuins (SIRTs) in AG-IM. Surveys of the genes negatively correlated with SIRT6 in public databases considered SIRT6 as tumor suppressors, which was confirmed by the cell proliferation and migration assays after transient transfection of SIRT6 overexpression vector into AGS cells. All the above observations were then confirmed by serial section-based immunohistochemistry against Ki-67, MUC2, MUC5AC, p53, and SIRT6 on the endoscopic submucosal dissection tissue. By contrast, the expression of the other HMGs varied even opposite within same family. Taken together, this study preliminarily demonstrated the two-edged sword role of SIRTs in ICS and, by extension, showed that the roles of HMGs in ICS were probably stage specific. Our study may provide new insights into and attract attention on gastric prevention and therapy targeting HMGs.

Epigenetic Therapeutics Targeting NRF2/KEAP1 Signaling in Cancer Oxidative Stress

The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) and its negative regulator kelch-like ECH-associated protein 1 (KEAP1) regulate various genes involved in redox homeostasis, which protects cells from stress conditions such as reactive oxygen species and therefore exerts beneficial effects on suppression of carcinogenesis. In addition to their pivotal role in cellular physiology, accumulating innovative studies indicated that NRF2/KEAP1-governed pathways may conversely be oncogenic and cause therapy resistance, which was profoundly modulated by epigenetic mechanism. Therefore, targeting epigenetic regulation in NRF2/KEAP1 signaling is a potential strategy for cancer treatment. In this paper, the current knowledge on the role of NRF2/KEAP1 signaling in cancer oxidative stress is presented, with a focus on how epigenetic modifications might influence cancer initiation and progression. Furthermore, the prospect that epigenetic changes may be used as therapeutic targets for tumor treatment is also investigated.

Manipulating Histone Acetylation Leads to Antitumor Effects in Hemangiosarcoma Cells

Canine hemangiosarcoma (HSA) is a malignant tumor derived from endothelial cells. No effective treatment has yet been developed because of the lack of understanding of its pathogenesis. Histone acetylation, an epigenetic modification, is highly associated with cancer pathogenesis. Manipulating histone acetylation by histone deacetylase inhibitors (HDACi) or bromodomain and extraterminal domain inhibitors (BETi) is one approach to treat various cancers. However, the role of histone acetylation in HSA remains unknown. This study aimed to investigate how histone acetylation functions in HSA pathogenesis using two HDACi, suberanilohydroxamic acid (SAHA) and valproic acid (VPA), and one BETi, JQ1, in vitro and in vivo. Histone acetylation levels were high in cell lines and heterogeneous in clinical cases. SAHA and JQ1 induced apoptosis in HSA cell lines. HSA cell lines treated with SAHA and VPA upregulated inflammatory-related genes and attracted macrophage cell line RAW264 cells, which suggests that SAHA and VPA can affect immune responses. JQ1 stimulated autophagy and inhibited the cell cycle in HSA cell lines. Finally, we demonstrated that JQ1 suppressed HSA tumor cell proliferation in vivo although SAHA and VPA did not affect tumor growth. These results suggest that BETi can be alternative drugs for HSA treatment. Although further research is required, our study indicated that dysregulation of histone acetylation is likely to be involved in HSA malignancy. This article is protected by copyright. All rights reserved.

Natural Bioactive Compounds Targeting Histone Deacetylases in Human Cancers: Recent Updates

Cancer is a complex pathology that causes a large number of deaths worldwide. Several risk factors are involved in tumor transformation, including epigenetic factors. These factors are a set of changes that do not affect the DNA sequence, while modifying the gene’s expression. Histone modification is an essential mark in maintaining cellular memory and, therefore, loss of this mark can lead to tumor transformation. As these epigenetic changes are reversible, the use of molecules that can restore the functions of the enzymes responsible for the changes is therapeutically necessary. Natural molecules, mainly those isolated from medicinal plants, have demonstrated significant inhibitory properties against enzymes related to histone modifications, particularly histone deacetylases (HDACs). Flavonoids, terpenoids, phenolic acids, and alkaloids exert significant inhibitory effects against HDAC and exhibit promising epi-drug properties. This suggests that epi-drugs against HDAC could prevent and treat various human cancers. Accordingly, the present study aimed to evaluate the pharmacodynamic action of different natural compounds extracted from medicinal plants against the enzymatic activity of HDAC.

Gastric cancer: An epigenetic view

Gastric cancer (GC) poses a serious threat worldwide with unfavorable prognosis mainly due to late diagnosis and limited therapies. Therefore, precise molecular classification and search for potential targets are required for diagnosis and treatment, as GC is complicated and heterogeneous in nature. Accumulating evidence indicates that epigenetics plays a vital role in gastric carcinogenesis and progression, including histone modifications, DNA methylation and non-coding RNAs. Epigenetic biomarkers and drugs are currently under intensive evaluations to ensure efficient clinical utility in GC. In this review, key epigenetic alterations and related functions and mechanisms are summarized in GC. We focus on integration of existing epigenetic findings in GC for the bench-to-bedside translation of some pivotal epigenetic alterations into clinical practice and also describe the vacant field waiting for investigation.

Vitamin D and Gastric Cancer: A Ray of Sunshine?

Gastric cancer (GC) is one of the most aggressive malignancies, currently ranking third among cancers leading to death worldwide. Despite the recent advancements in GC research, it is most often diagnosed during the terminal stages and with limited treatment modalities contributing to its poor prognosis and a lower survival rate.

Much research has provided conflicting results between a vitamin D deficient status and the development of GC. Vitamin D is a well-known and essential hormone classically known to regulate calcium and phosphate absorption, enabling adequate mineralization of the skeletal system. However, the function of vitamin D is multidimensional. It possesses unique roles, including acting as antioxidants or immunomodulators while crossing the cell membrane, performing several intracellular functions, participating in gene regulation, and controlling the proliferation and invasion of cancer cells, including those of GC.

In light of this, it is imperative to analyze the causes of GC, review the factors that can be used to enhance the effectiveness of treatments, and discover the tools to determine prognosis, reduce mortality, and prevent GC development. In this review, we have summarized recent investigations on multiple associations between vitamin D and GC, emphasizing genetic associations, vitamin D receptors, and the prevalence of hormone deficiency in those developing this aggressive malignancy.

Atomistic insights into the selective therapeutic activity of 6-(2,4-difluorophenoxy)-5-((ethylmethyl)pyridine-3-yl)-8-methylpyrrolo[1,2-a]pyrazin-1(2H)-one towards bromodomain-containing proteins

Cross-target effect has been one of the major mechanisms of drug toxicity, this has necessitated the design of inhibitors that are specifically tailored to target particular biomolecules. 6-(2,4-difluorophenoxy)-5-((ethylmethyl)pyridine-3-yl)-8-methylpyrrolo[1,2-a] pyrazin-1(2H)-one (Cpd38) is an inhibitor possessing high inhibition rate and tailored specificity towards bromodomain-containing protein 4 (BRD4). In this research, we used an array of computational techniques to provide insight at the atomistic level the specific targeting of BRD4 by Cpd38 relative to the binding of Cpd38 with E1A binding protein P300 (EP300); another bromodomain-containing protein (BCP). Comparatively, binding of Cpd38 improved the conformational stability and compactness of BRD4 protein when compared to the Cpd38 bound EP300. Also, Cpd38 induced a conformational change in the active site of BRD4 that facilitated a complementary pose between Cpd38 and BRD4 suitable for effective atomistic interactions. Expectedly, thermodynamic calculations revealed that the Cpd38-BRD4 system had higher binding energy (-36.11 Kcal/mol) than the Cpd38-EP300 system with a free binding energy of -15.86 Kcal/mol. Noteworthy is the opposing role Trp81 (acting as hydrogen bond acceptor) and Pro1074 (acting as hydrogen bond donor) found on the WPF and LPF loops respectively play in maintaining Cpd38 stability. Furthermore, the hydrogen bond acceptor/donator ratio was approximately 4:1 in Cpd38-BRD4 system compared with 2:1 in Cpd38-EP300 system. Taken together, atomistic insights and structural perspectives detailed in this report supplements the experimental report supporting the improved selectivity of Cpd38 for BRD4 ahead of other BCPs while providing leeway for the future design of BET selective agents with better pharmacological profile.

Epigenetic enzymes: A role in aging and prospects for pharmacological targeting

The development of interventions aimed at improving healthspan is one of the priority tasks for the academic and public health authorities. It is also the main objective of a novel branch in biogerontological research, geroscience. According to the geroscience concept, targeting aging is an effective way to combat age-related disorders. Since aging is an exceptionally complex process, system-oriented integrated approaches seem most appropriate for such an interventional strategy. Given the high plasticity and adaptability of the epigenome, epigenome-targeted interventions appear highly promising in geroscience research. Pharmaceuticals targeted at mechanisms involved in epigenetic control of gene activity are actively developed and implemented to prevent and treat various aging-related conditions such as cardiometabolic, neurodegenerative, inflammatory disorders, and cancer. In this review, we describe the roles of epigenetic mechanisms in aging; characterize enzymes contributing to the regulation of epigenetic processes; particularly focus on epigenetic drugs, such as inhibitors of DNA methyltransferases and histone deacetylases that may potentially affect aging-associated diseases and longevity; and discuss possible caveats associated with the use of epigenetic drugs.

Molecular alterations in gastric cancer and the surrounding intestinal metaplastic mucosa: an analysis of isolated glands

BACKGROUND

Intestinal metaplasias (IMs) are generally regarded as pre-neoplastic gastric lesions. However, molecular alterations including genetic and epigenetic changes occurring in individual IM glands are not well defined.

AIMS

We sought to identify DNA methylation status, microsatellite instability (MSI) and allelic imbalance (AI) occurring in individual IM glands and non-IM glands within the same mucosa.

METHODS

We divided examined isolated gland obtained from GC into 4 components: isolated cancer, antral isolated intestinal metaplastic tissue, antral isolated non-metaplastic gland and isolated non-metaplastic gland derived from the greater curvature of the most distant gastric body without mucosal atrophy. We examined AI and microsatellite instability statuses using PCR-based microsatellite analysis. Next, the DNA methylation status (high methylation epigenome [HME], intermediate methylation epigenome [IME], and low methylation epigenome [LME]) was investigated. DNA methylation analysis of CDKN2A, mir34-b/c and MLHI genes was also performed.

RESULTS

Although antral isolated IM glands were characterized by IME, isolated non-IM glands showed LME. In isolated cancer glands, HME was frequently found, compared with isolated non-IM glands. DNA methylation of mir34-b/c was common in isolated cancer and IM glands, whereas DNA methylation of CDKN2A was a rare event in isolated samples. The MLH1 gene was not methylated in isolated non-IM glands. Although multiple AIs were frequently found in isolated cancer glands, a few AIs were detected in isolated IM glands.

CONCLUSIONS

We suggest that the DNA methylation status and the status of the mir34-b/c gene among isolated samples of IMs and isolated non-IM glands have an impact on IM development.

Zinc Metalloproteins in Epigenetics and Their Crosstalk

More than half a century ago, zinc was established as an essential micronutrient for normal human physiology. In silico data suggest that about 10% of the human proteome potentially binds zinc. Many proteins with zinc-binding domains (ZBDs) are involved in epigenetic modifications such as DNA methylation and histone modifications, which regulate transcription in physiological and pathological conditions. Zinc metalloproteins in epigenetics are mainly zinc metalloenzymes and zinc finger proteins (ZFPs), which are classified into writers, erasers, readers, editors, and feeders. Altogether, these classes of proteins engage in crosstalk that fundamentally maintains the epigenome's modus operandi. Changes in the expression or function of these proteins induced by zinc deficiency or loss of function mutations in their ZBDs may lead to aberrant epigenetic reprogramming, which may worsen the risk of non-communicable chronic diseases. This review attempts to address zinc's role and its proteins in natural epigenetic programming and artificial reprogramming and briefly discusses how the ZBDs in these proteins interact with the chromatin.

Sodium Butyrate Combined with Docetaxel for the Treatment of Lung Adenocarcinoma A549 Cells by Targeting Gli1

Purpose

This study is aimed to investigate the combined treating efficacy of sodium butyrate and docetaxel on proliferation and apoptosis of the lung adenocarcinoma A549 cell line based on Gli1 regulation in vitro and in vivo.

Materials and Methods

RNA interference method was used to overexpress Gli1 in A549 cells. Cells were treated with varying concentrations of sodium butyrate, docetaxel or both in combination. CCK-8, colony formation assay, Hoechst 33258 staining, flow cytometry and TUNEL assay were employed to detect proliferation, cell cycle and apoptosis. qRT-PCR and Western blot analysis were applied to detect the mRNA and protein expression of Gli1. In vivo tumorigenicity was detected by tumor transplantation in nude mice. Downstream protein levels of Gli1 were detected using Western blot assay.

Results

It was found that sodium butyrate or docetaxel alone, respectively, inhibited proliferation and promoted apoptosis of A549 cells in vitro and in vivo, while the combination of the two generated significantly higher responses, which were also effective in another lung adenocarcinoma cell line H1299. Furthermore, the combined therapy had an additive effect in suppressing Gli1 expression and regulating the expression of its downstream proteins that involve in proliferation, cell cycle and apoptosis of A549 cells in vitro and in vivo, including decreased protein expression of Ki-67, CDK1, CDK2, Cyclin D1, Bcl-2 and Survivin, and increased protein expression of Cyclin A, p21, Bax and cleaved-Caspase 3. On the other hand, Gli1 overexpression perceptibly reversed the above-mentioned additive effect in vitro and in vivo.

Conclusion

This study demonstrates that the combined therapy of sodium butyrate and docetaxel additively inhibits proliferation and promotes apoptosis of A549 lung adenocarcinoma cells via suppressing Gli1 expression in vitro and in vivo. Targeting Gli1 by the combined therapy may provide new insights into the therapeutic management of patients with lung adenocarcinoma.

Bio-inspired construction of a semi-artificial enzyme complex for detecting histone acetyltransferases activity

Herein, an electrochemical method to detect histone acetyltransferases activity (HAT) has been developed based on the reduction of G-Quadruplex-Cu(ii) metalloenzyme activity. A G-quadruplex-Cu(ii) metalloenzyme has excellent peroxidase property, generating strong electrochemical signal. In the presence of HAT, it can catalyze substrate peptide acetylation and produce large amounts of Coenzyme A (CoA). The electrochemical signal of G-Quadruplex-Cu(ii) is weak due to the competitive combination between G-Quadruplex and CoA with Cu(ii), resulting in the direct quantitative detection of HAT. The detection limit for HAT is about 0.14 nM using this strategy and the cost is quite low since the developed assay method is label-free and antibody-free due to the use of low-cost DNA and Cu2+. Since this assay method can be employed to detect HAT in serum, it may be useful in disease diagnosis in the future.

Systems Biology of Gastric Cancer: Perspectives on the Omics-Based Diagnosis and Treatment

Gastric cancer is the fifth most diagnosed cancer in the world, affecting more than a million people and causing nearly 783,000 deaths each year. The prognosis of advanced gastric cancer remains extremely poor despite the use of surgery and adjuvant therapy. Therefore, understanding the mechanism of gastric cancer development, and the discovery of novel diagnostic biomarkers and therapeutics are major goals in gastric cancer research. Here, we review recent progress in application of omics technologies in gastric cancer research, with special focus on the utilization of systems biology approaches to integrate multi-omics data. In addition, the association between gastrointestinal microbiota and gastric cancer are discussed, which may offer insights in exploring the novel microbiota-targeted therapeutics. Finally, the application of data-driven systems biology and machine learning approaches could provide a predictive understanding of gastric cancer, and pave the way to the development of novel biomarkers and rational design of cancer therapeutics.

Histone modifications in epigenetic regulation of cancer: Perspectives and achieved progress

Epigenetic changes associated with histone modifications play an important role in the emergence and maintenance of the phenotype of various cancer types. In contrast to direct mutations in the main DNA sequence, these changes are reversible, which makes the development of inhibitors of enzymes of post-translational histone modifications one of the most promising strategies for the creation of anticancer drugs. To date, a wide variety of histone modifications have been found that play an important role in the regulation of chromatin state, gene expression, and other nuclear events. This review examines the main features of the most common and studied epigenetic histone modifications with a proven role in the pathogenesis of a wide range of malignant neoplasms: acetylation / deacetylation and methylation / demethylation of histone proteins, as well as the role of enzymes of the HAT / HDAC and HMT / HDMT families in the development of oncological pathologies. The data on the relationship between histone modifications and certain types of cancer are presented and discussed. Special attention is devoted to the consideration of various strategies for the development of epigenetic inhibitors. The main directions of the development of inhibitors of histone modifications are analyzed and effective strategies for their creation are identified and discussed. The most promising strategy is the use of multitarget drugs, which will affect multiple molecular targets of cancer. A critical analysis of the current status of approved epigenetic anticancer drugs has also been performed.

Epigallocatechin-3-gallate (EGCG) Alters Histone Acetylation and Methylation and Impacts Chromatin Architecture Profile in Human Endothelial Cells

Epigallocatechin gallate (EGCG), the main green tea polyphenol, exerts a wide variety of biological actions. Epigenetically, the catechin has been classified as a DNMTs inhibitor, however, its impact on histone modifications and chromatin structure is still poorly understood. The purpose of this study was to find the impact of EGCG on the histone posttranslational modifications machinery and chromatin remodeling in human endothelial cells of both microvascular (HMEC-1) and vein (HUVECs) origin. We analyzed the methylation and acetylation status of histones (Western blotting), as well as assessed the activity (fluorometric assay kit) and gene expression (qPCR) of the enzymes playing a prominent role in shaping the human epigenome. The performed analyses showed that EGCG increases histone acetylation (H3K9/14ac, H3ac), and methylation of both active (H3K4me3) and repressive (H3K9me3) chromatin marks. We also found that the catechin acts as an HDAC inhibitor in cellular and cell-free models. Additionally, we observed that EGCG affects chromatin architecture by reducing the expression of heterochromatin binding proteins: HP1α, HP1γ. Our results indicate that EGCG promotes chromatin relaxation in human endothelial cells and presents a broad epigenetic potential affecting expression and activity of epigenome modulators including HDAC5 and 7, p300, CREBP, LSD1 or KMT2A.

H3K18Ac as a Marker of Cancer Progression and Potential Target of Anti-Cancer Therapy

Acetylation and deacetylation are posttranslational modifications (PTMs) which affect the regulation of chromatin structure and its remodeling. Acetylation of histone 3 at lysine placed on position 18 (H3K18Ac) plays an important role in driving progression of many types of cancer, including breast, colon, lung, hepatocellular, pancreatic, prostate, and thyroid cancer. The aim of this review is to analyze and discuss the newest findings regarding the role of H3K18Ac and acetylation of other histones in carcinogenesis. We summarize the level of H3K18Ac in different cancer cell lines and analyze its association with patients’ outcomes, including overall survival (OS), progression-free survival (PFS), and disease-free survival (DFS). Finally, we describe future perspectives of cancer therapeutic strategies based on H3K18 modifications.