H3K27 Methylation: A Focal Point of Epigenetic Deregulation in Cancer

Epigenetic alterations and advancement of lymphoma treatment

Lymphomas, complex and heterogeneous malignant tumors, originate from the lymphopoietic system. These tumors are notorious for their high recurrence rates and resistance to treatment, which leads to poor prognoses. As ongoing research has shown, epigenetic modifications like DNA methylation, histone modifications, non-coding RNA regulation, and RNA modifications play crucial roles in lymphoma pathogenesis. Epigenetic modification-targeting drugs have exhibited therapeutic efficacy and tolerability in both monotherapy and combination lymphoma therapy. This review discusses pathogenic mechanisms and potential epigenetic therapeutic targets in common lymphomas, offering new avenues for lymphoma diagnosis and treatment. We also discuss the shortcomings of current lymphoma treatments, while suggesting potential areas for future research, in order to improve the prediction and prognosis of lymphoma.

SETD4 inhibits prostate cancer development by promoting H3K27me3-mediated NUPR1 transcriptional repression and cell cycle arrest

The suppressor of variegation enhancer of zeste-trithorax (SET) domain methyltransferases have been reported to function as key regulators in multiple tumor types by catalyzing histone lysine methylation. Nevertheless, our understanding on the role of these lysine methyltransferases, including SETD4, in prostate cancer (PCa) remains limited. Hence, the specific role of SETD4 in PCa was investigated in this study. The expression of SETD4 in PCa cells and tissue samples was downregulated in PCa cells and tissue specimens, and decreased SETD4 expression led to inferior clinicopathological characteristics in patients with PCa. knockdown of SETD4 facilitated the proliferation of PCa cells and accelerated cell cycle progression. Mechanistically, SETD4 repressed NUPR1 transcription by methylating H3K27 to generate H3K27me3, subsequently inactivated Akt pathway and impeded the tumorigenesis of PCa. Our results highlight that SETD4 prevents the development of PCa by catalyzing the methylation of H3K27 and suppressing NUPR1 transcription, subsequently inactivating the Akt signaling pathway. The findings suggest the potential application of SETD4 in PCa prognosis and therapeutics.

EZH2 Gene Knockdown Inhibits Sheep Pituitary Cell Proliferation via Downregulating the AKT/ERK Signaling Pathway

Pituitary gonadotropins perform essential functions in mammalian reproduction by stimulating gametogenesis and steroidogenesis in the ovaries and testicles. EZH2 is a histone methyltransferase that inhibits proliferation and aggravates apoptosis in stem cells subjected to pathological stimuli. However, the expression and molecular mechanisms of EZH2 in pituitary cells in vitro have not been extensively studied. In this study, the relative abundances of EZH2 mRNA (p < 0.01) and protein (p < 0.05) expression were larger in the pituitary cells of Hu sheep with relatively greater fecundity (GF) compared to those with lesser fecundity (LF). Loss-of-function examinations demonstrated that EZH2 gene knockdown led to an earlier induction of apoptosis in sheep pituitary cells (PCs). The relative abundance of CASP3, CASP9, and BAX was increased (p < 0.01), while BCL2's abundance was less decreased (p < 0.01) in PCs where there was EZH2 gene knockdown. Additionally, cell proliferation (p < 0.01) and viability (p < 0.01) were decreased in EZH2-knockdown sheep PCs, and the cell cycle was blocked compared to a negative control (NC). Notably, EZH2 gene knockdown led to reduced abundances of gonadotropin subunit gene transcripts (FSHβ, p < 0.05) and reduced FSH release (p < 0.01) from PCs. EZH2 gene knockdown led to reduced phosphorylation of AKT, ERK, and mTOR (p < 0.01). The results suggest that EZH2 regulates pituitary cell proliferation, apoptosis, and FSH secretion through modulation of the AKT/ERK signaling pathway, providing a foundation for further study of pituitary cell functions.

Less Severe Polymicrobial Sepsis in Conditional mgmt-Deleted Mice Using LysM-Cre System, Impacts of DNA Methylation and MGMT Inhibitor in Sepsis

The O6-methylguanine-DNA methyltransferase (MGMT) is a DNA suicide repair enzyme that might be important during sepsis but has never been explored. Then, the proteomic analysis of lipopolysaccharide (LPS)-stimulated wild-type (WT) macrophages increased proteasome proteins and reduced oxidative phosphorylation proteins compared with control, possibly related to cell injury. With LPS stimulation, mgmt null (mgmt^flox/flox; LysM-Cre^cre/-) macrophages demonstrated less profound inflammation; supernatant cytokines (TNF-α, IL-6, and IL-10) and pro-inflammatory genes (iNOS and IL-1β), with higher DNA break (phosphohistone H2AX) and cell-free DNA, but not malondialdehyde (the oxidative stress), compared with the littermate control (mgmt^flox/flox; LysM-Cre^-/-). In parallel, mgmt null mice (MGMT loss only in the myeloid cells) demonstrated less severe sepsis in the cecal ligation and puncture (CLP) model (with antibiotics), as indicated by survival and other parameters compared with sepsis in the littermate control. The mgmt null protective effect was lost in CLP mice without antibiotics, highlighting the importance of microbial control during sepsis immune modulation. However, an MGMT inhibitor in CLP with antibiotics in WT mice attenuated serum cytokines but not mortality, requiring further studies. In conclusion, an absence of mgmt in macrophages resulted in less severe CLP sepsis, implying a possible influence of guanine DNA methylation and repair in macrophages during sepsis.

Less Severe Lipopolysaccharide-Induced Inflammation in Conditional mgmt-Deleted Mice with LysM-Cre System: The Loss of DNA Repair in Macrophages

Despite the known influence of DNA methylation from lipopolysaccharide (LPS) activation, data on the O6-methylguanine-DNA methyltransferase (MGMT, a DNA suicide repair enzyme) in macrophages is still lacking. The transcriptomic profiling of epigenetic enzymes from wild-type macrophages after single and double LPS stimulation, representing acute inflammation and LPS tolerance, respectively, was performed. Small interfering RNA (siRNA) silencing of mgmt in the macrophage cell line (RAW264.7) and mgmt null (mgmt^flox/flox; LysM-Cre^cre/-) macrophages demonstrated lower secretion of TNF-α and IL-6 and lower expression of pro-inflammatory genes (iNOS and IL-1β) compared with the control. Macrophage injury after a single LPS dose and LPS tolerance was demonstrated by reduced cell viability and increased oxidative stress (dihydroethidium) compared with the activated macrophages from littermate control mice (mgmt^flox/flox; LysM-Cre^-/-). Additionally, a single LPS dose and LPS tolerance also caused mitochondrial toxicity, as indicated by reduced maximal respiratory capacity (extracellular flux analysis) in the macrophages of both mgmt null and control mice. However, LPS upregulated mgmt only in LPS-tolerant macrophages but not after the single LPS stimulation. In mice, the mgmt null group demonstrated lower serum TNF-α, IL-6, and IL-10 than control mice after either single or double LPS stimulation. Suppressed cytokine production resulting from an absence of mgmt in macrophages caused less severe LPS-induced inflammation but might worsen LPS tolerance.

Less Severe Sepsis in Cecal Ligation and Puncture Models with and without Lipopolysaccharide in Mice with Conditional Ezh2-Deleted Macrophages (LysM-Cre System)

Despite a previous report on less inflammatory responses in mice with an absence of the enhancer of zeste homologue 2 (Ezh2), a histone lysine methyltransferase of epigenetic regulation, using a lipopolysaccharide (LPS) injection model, proteomic analysis and cecal ligation and puncture (CLP), a sepsis model that more resembles human conditions was devised. As such, analysis of cellular and secreted protein (proteome and secretome) after a single LPS activation and LPS tolerance in macrophages from Ezh2 null (Ezh2^flox/flox; LysM-Cre^cre/-) mice (Ezh2 null) and the littermate control mice (Ezh2^fl/fl; LysM-Cre^-/-) (Ezh2 control) compared with the unstimulated cells from each group indicated fewer activities in Ezh2 null macrophages, especially by the volcano plot analysis. Indeed, supernatant IL-1β and expression of genes in pro-inflammatory M1 macrophage polarization (IL-1β and iNOS), TNF-α, and NF-κB (a transcription factor) were lower in Ezh2 null macrophages compared with the control. In LPS tolerance, downregulated NF-κB compared with the control was also demonstrated in Ezh2 null cells. In CLP sepsis mice, those with CLP alone and CLP at 2 days after twice receiving LPS injection, representing sepsis and sepsis after endotoxemia, respectively, symptoms were less severe in Ezh2 null mice, as indicated by survival analysis and other biomarkers. However, the Ezh2 inhibitor improved survival only in CLP, but not LPS with CLP. In conclusion, an absence of Ezh2 in macrophages resulted in less severe sepsis, and the use of an Ezh2 inhibitor might be beneficial in sepsis.

Epigenetic and Long-Term Effects of Nicotine on Biology, Behavior, and Health

Tobacco and nicotine use are associated with disease susceptibility and progression. Health challenges associated with nicotine and smoking include developmental delays, addiction, mental health and behavioral changes, lung disease, cardiovascular disease, endocrine disorders, diabetes, immune system changes, and cancer. Increasing evidence suggests that nicotine-associated epigenetic changes may mediate or moderate the development and progression of a myriad of negative health outcomes. In addition, nicotine exposure may confer increased lifelong susceptibility to disease and mental health challenges through alteration of epigenetic signaling. This review examines the relationship between nicotine exposure (and smoking), epigenetic changes, and maladaptive outcomes that include developmental disorders, addiction, mental health challenges, pulmonary disease, cardiovascular disease, endocrine disorders, diabetes, immune system changes, and cancer. Overall, findings support the contention that nicotine (or smoking) associated altered epigenetic signaling is a contributing factor to disease and health challenges.

The Regulatory Roles of Ezh2 in Response to Lipopolysaccharide (LPS) in Macrophages and Mice with Conditional Ezh2 Deletion with LysM-Cre System

The responses of macrophages to lipopolysaccharide (LPS) might determine the direction of clinical manifestations of sepsis, which is the immune response against severe infection. Meanwhile, the enhancer of zeste homologue 2 (Ezh2), a histone lysine methyltransferase of epigenetic regulation, might interfere with LPS response. Transcriptomic analysis on LPS-activated wild-type macrophages demonstrated an alteration of several epigenetic enzymes. Although the Ezh2-silencing macrophages (RAW264.7), using small interfering RNA (siRNA), indicated a non-different response to the control cells after a single LPS stimulation, the Ezh2-reducing cells demonstrated a less severe LPS tolerance, after two LPS stimulations, as determined by the higher supernatant TNF-α. With a single LPS stimulation, Ezh2 null (Ezh2flox/flox; LysM-Crecre/−) macrophages demonstrated lower supernatant TNF-α than Ezh2 control (Ezh2fl/fl; LysM-Cre−/−), perhaps due to an upregulation of Socs3, which is a suppressor of cytokine signaling 3, due to the loss of the Ezh2 gene. In LPS tolerance, Ezh2 null macrophages indicated higher supernatant TNF-α and IL-6 than the control, supporting an impact of the loss of the Ezh2 inhibitory gene. In parallel, Ezh2 null mice demonstrated lower serum TNF-α and IL-6 than the control mice after an LPS injection, indicating a less severe LPS-induced hyper-inflammation in Ezh2 null mice. On the other hand, there were similar serum cytokines after LPS tolerance and the non-reduction of serum cytokines after the second dose of LPS, indicating less severe LPS tolerance in Ezh2 null mice compared with control mice. In conclusion, an absence of Ezh2 in macrophages resulted in less severe LPS-induced inflammation, as indicated by low serum cytokines, with less severe LPS tolerance, as demonstrated by higher cytokine production, partly through the upregulated Socs3.

Mechanistic aspects of reversible methylation modifications of arginine and lysine of nuclear histones and their roles in human colon cancer

Developmental proceedings and maintenance of cellular homeostasis are regulated by the precise orchestration of a series of epigenetic events that eventually control gene expression. DNA methylation and post-translational modifications (PTMs) of histones are well-characterized epigenetic events responsible for fine-tuning gene expression. PTMs of histones bear molecular logic of gene expression at chromosomal territory and have become a fascinating field of epigenetics. Nowadays, reversible methylation on histone arginine and lysine is gaining increasing attention as a significant PTM related to reorganizing local nucleosomal structure, chromatin dynamics, and transcriptional regulation. It is now well-accepted and reported that histone marks play crucial roles in colon cancer initiation and progression by encouraging abnormal epigenomic reprogramming. It is becoming increasingly clear that multiple PTM marks at the N-terminal tails of the core histones cross-talk with one another to intricately regulate DNA-templated biological processes such as replication, transcription, recombination, and damage repair in several malignancies, including colon cancer. These functional cross-talks provide an additional layer of message, which spatiotemporally fine-tunes the overall gene expression regulation. Nowadays, it is evident that several PTMs instigate colon cancer development. How colon cancer-specific PTM patterns or codes are generated and how they affect downstream molecular events are uncovered to some extent. Future studies would address more about epigenetic communication, and the relationship between histone modification marks to define cellular functions in depth. This chapter will comprehensively highlight the importance of histone arginine and lysine-based methylation modifications and their functional cross-talk with other histone marks from the perspective of colon cancer development.

Direct assessment of histone function using histone replacement

Histones serve many purposes in eukaryotic cells in the regulation of diverse genomic processes, including transcription, replication, DNA repair, and chromatin organization. As such, experimental systems to assess histone function are fundamental resources toward elucidating the regulation of activities occurring on chromatin. One set of important tools for investigating histone function are histone replacement systems, in which endogenous histone expression can be partially or completely replaced with a mutant histone. Histone replacement systems allow systematic screens of histone regulatory functions and the direct assessment of functions for histone residues. In this review, we describe existing histone replacement systems in model organisms, the benefits and limitations of these systems, and opportunities for future research with histone replacement strategies.

Diffuse Intrinsic Pontine Glioma: Molecular Landscape, Evolving Treatment Strategies and Emerging Clinical Trials

Diffuse intrinsic pontine glioma (DIPG) is a type of intrinsic brainstem glial tumor that occurs primarily in the pediatric population. DIPG is initially diagnosed based on clinical symptoms and the characteristic location on imaging. Histologically, these tumors are characterized by a heterogenous population of cells with multiple genetic mutations and high infiltrative capacity. The most common mutation seen in this group is a lysine to methionine point mutation seen at position 27 (K27M) within histone 3 (H3). Tumors with the H3 K27M mutation, are considered grade 4 and are now categorized within the H3 K27-altered diffuse midline glioma category by World Health Organization classification. Due to its critical location and aggressive nature, DIPG is resistant to the most eradicative treatment and is universally fatal; however, modern advances in the surgical techniques resulting in safe biopsy of the lesion have significantly improved our understanding of this disease at the molecular level. Genomic analysis has shown several mutations that play a role in the pathophysiology of the disease and can be targeted therapeutically. In this review, we will elaborate on DIPG from general aspects and the evolving molecular landscape. We will also review innovative therapeutic options that have been trialed along with new promising treatments on the horizon.

Role of Histone Post-Translational Modifications in Inflammatory Diseases

Inflammation is a defensive reaction for external stimuli to the human body and generally accompanied by immune responses, which is associated with multiple diseases such as atherosclerosis, type 2 diabetes, Alzheimer’s disease, psoriasis, asthma, chronic lung diseases, inflammatory bowel disease, and multiple virus-associated diseases. Epigenetic mechanisms have been demonstrated to play a key role in the regulation of inflammation. Common epigenetic regulations are DNA methylation, histone modifications, and non-coding RNA expression; among these, histone modifications embrace various post-modifications including acetylation, methylation, phosphorylation, ubiquitination, and ADP ribosylation. This review focuses on the significant role of histone modifications in the progression of inflammatory diseases, providing the potential target for clinical therapy of inflammation-associated diseases.

Epigenetic Determinants of Racial Disparity in Breast Cancer: Looking beyond Genetic Alterations

Simple Summary

A substantial disparity in breast cancer incidence and mortality exists between African American (AA) and European American (EA) women. However, the basis for these disparities is poorly understood. In this article, we describe that gene–environment interactions mediated through epigenetic modifications may play a significant role in racial disparities in BC incidence and outcomes. Our in silico analyses and an in-depth literature survey suggest that there exists a significant difference in epigenetic patterns between AA and EA women with breast cancer. Herein, we describe the environmental factors that contribute to these epigenetic changes, which may underlie the disparate racial burden in patients with breast cancer. We suggest that AA women with higher basal epigenetic changes, may have higher pre-disposition to cancer onset, and an aggressive disease course. Pre-existing racial differences in epigenetic profiles of breast tissues raises the possibility of examining these profiles for early diagnosis.

Abstract

Breast cancer (BC) is the most commonly diagnosed cancer in women. Despite advancements in BC screening, prevention, and treatment, BC incidence and mortality remain high among African American (AA) women. Compared with European American (EA) women, AA women tend to be diagnosed with more advanced and aggressive tumors and exhibit worse survival outcomes. Most studies investigating the determinants of racial disparities in BC have focused on genetic factors associated with African ancestry. However, various environmental and social stressors over an individual’s life course can also shape racial stratification in BC. These social and environmental exposures result in long-term changes in gene expression mediated by epigenetic mechanisms. Epigenetics is often portrayed as an intersection of socially patterned stress and genetic expression. The enduring nature of epigenetic changes makes them suitable for studying the effects of different environmental exposures over an individual’s life course on gene expression. The role of differential social and environmental exposures in racial disparities in BC suggests varied epigenetic profiles or signatures associated with specific BC subtypes in AA and EA women. These epigenetic profiles in EA and AA women could be used as biomarkers for early BC diagnosis and disease prognosis and may prove valuable for the development of targeted therapies for BC. This review article discusses the current state of knowledge regarding epigenetic differences between AA and EA women with BC. We also discuss the role of socio-environmental factors, including psychosocial stress, environmental toxicants, and dietary factors, in delineating the different epigenetic profiles in AA and EA patients with BC.

Epigenetic Comparison of CHO Hosts and Clones Reveals Divergent Methylation and Transcription Patterns Across Lineages

In this study, we examined DNA methylation and transcription profiles of recombinant clones derived from two different Chinese hamster ovary hosts. We found striking epigenetic differences between the clones, with global hypomethylation in the host 1 clones that produce bispecific antibody with higher productivity and complex assembly efficiency. Whereas the methylation patterns were found mostly inherited from the host, the host 1 clones exhibited continued demethylation reflected by the hypomethylation of newly emerged differential methylation regions (DMRs) even at the clone development stage. Several interconnected biological functions and pathways including cell adhesion, regulation of ion transport, and cholesterol biosynthesis were significantly altered between the clones at the RNA expression level and contained DMR in the promoter and/or gene-body of the transcripts, suggesting epigenetic regulation. Indeed, expression changes of epigenetic regulators were observed including writers (Dnmt1, Setdb1), readers (Mecp2), and erasers (Tet3, Kdm3a, Kdm1b/5c) involved in CpG methylation, histone methylation and heterochromatin maintenance. In addition, we identified putative transcription factors that may be readers or effectors of the epigenetic regulation in these clones. By combining transcriptomics with DNA methylation data, we identified potential processes and factors that may contribute to the variability in cell physiology between different production hosts. This article is protected by copyright. All rights reserved.

Targeting chemotherapy to de-condensed H3K27me3-marked chromatin of AML cells enhances leukemia suppression

Despite treatment with intensive chemotherapy, acute myeloid leukemia (AML) remains an aggressive malignancy with a dismal outcome in most patients. We found that AML cells exhibit an unusually rapid accumulation of the repressive histone mark H3K27me3 on nascent DNA. In cell lines, primary cells and xenograft mouse models, inhibition of the H3K27 histone methyltransferase EZH2 to de-condense the H3K27me3-marked chromatin of AML cells enhanced chromatin accessibility and chemotherapy-induced DNA damage, apoptosis, and leukemia suppression. These effects were further promoted when chromatin de-condensation of AML cells was induced upon S-phase entry after release from a transient G1 arrest mediated by CDK4/6 inhibition. In the p53-null KG-1 and THP-1 AML cell lines, EZH2 inhibitor and doxorubicin co-treatment induced transcriptional reprogramming that was, in part, dependent on de-repression of H3K27me3-marked gene promoters and led to increased expression of cell death-promoting and growth-inhibitory genes. In conclusion, decondensing H3K27me3-marked chromatin by EZH2 inhibition represents a promising approach to improve the efficacy of DNA-damaging cytotoxic agents in AML patients. This strategy might allow for a lowering of chemotherapy doses with a consequent reduction of treatment-related side effects in elderly AML patients or those with significant comorbidities.

H3K27me3 loss indicates an increased risk of recurrence in the Tübingen meningioma cohort

Background

A loss of the trimethylation of lysine 27 of histone H3 (H3K27me3) in meningioma has been recently suggested as an adjunct to identify subsets of higher risk of recurrence. The aim of the present study was to assess the prognostic value of H3K27 histone trimethylation and its potential clinical utility in the “Tübingen meningioma cohort.”

Methods

Patients who underwent meningioma resection between October 2003 and December 2015 at the University Hospital Tübingen were included. Immunohistochemical stainings for H3K27me3 and the proliferation marker MIB1 were assessed and correlated with clinical parameters using univariate and multivariate Cox regressions as well as Pearson's chi-squared and log-rank test.

Results

Overall, 1268 meningiomas were analyzed with a female to male ratio of 2.6 and a mean age of 58.7 years (range 8.3–91.0). With 163 cases lost to follow up, 1103 cases were available for further analysis with a mean follow-up of 40.3 months (range 1.1–186.3). Male gender, younger age, intracranial tumor localization, progressive tumor, subtotal resection, higher WHO grade, increased MIB1 rate, and loss of H3K27me3 were significant negative prognostic factors in the univariate analysis. H3K27me3 status and all other prognostic factors, except age and tumor location, remained significant in the multivariate model. Furthermore, adjuvant radiotherapy was an independent positive prognostic factor.

Conclusions

Loss of H3K27me3 combined with MIB1 labeling index are independent prognostic factors in meningioma. These data from the Tübingen meningioma cohort support the clinical utility of H3K27me3 immunohistochemical staining in meningioma and its integration into the routine histopathological workup.

Role of Virus-Induced Host Cell Epigenetic Changes in Cancer

The tumor viruses human T-lymphotropic virus 1 (HTLV-1), hepatitis C virus (HCV), Merkel cell polyomavirus (MCPyV), high-risk human papillomaviruses (HR-HPVs), Epstein-Barr virus (EBV), Kaposi’s sarcoma-associated herpes virus (KSHV) and hepatitis B virus (HBV) account for approximately 15% of all human cancers. Although the oncoproteins of these tumor viruses display no sequence similarity to one another, they use the same mechanisms to convey cancer hallmarks on the infected cell. Perturbed gene expression is one of the underlying mechanisms to induce cancer hallmarks. Epigenetic processes, including DNA methylation, histone modification and chromatin remodeling, microRNA, long noncoding RNA, and circular RNA affect gene expression without introducing changes in the DNA sequence. Increasing evidence demonstrates that oncoviruses cause epigenetic modifications, which play a pivotal role in carcinogenesis. In this review, recent advances in the role of host cell epigenetic changes in virus-induced cancers are summarized.

WNT/β-catenin-suppressed FTO expression increases m6A of c-Myc mRNA to promote tumor cell glycolysis and tumorigenesis

FTO removes the N6-methyladenosine (m⁶A) modification from genes and plays a critical role in cancer development. However, the mechanisms underlying the regulation of FTO and its subsequent impact on the regulation of the epitranscriptome remain to be further elucidated. Here, we demonstrate that FTO expression is downregulated and inversely correlated with poor survival of lung adenocarcinoma patients. Mechanistically, Wnt signaling induces the binding of EZH2 to β-catenin. This protein complex binds to the LEF/TCF-binding elements at the promoter region of FTO, where EZH2 enhances H3K27me3 and inhibits FTO expression. Downregulated FTO expression substantially enhances the m⁶A levels in the mRNAs of a large number of genes in critical pathways, particularly metabolic pathway genes, such as MYC. Enhanced m⁶A levels on MYC mRNA recruit YTHDF1 binding, which promotes MYC mRNA translation and a subsequent increase in glycolysis and proliferation of tumor cells and tumorigenesis. Our findings uncovered a critical mechanism of epitranscriptome regulation by Wnt/β-catenin-mediated FTO downregulation and underscored the role of m⁶A modifications of MYC mRNA in regulating tumor cell glycolysis and growth.

Environmental pollutants exposure and male reproductive toxicity: The role of epigenetic modifications

Male fertility rates have shown a progressive decrease in recent decades. There is a growing concern about the male reproductive dysfunction caused by environmental pollutants exposure, however the underlying molecular mechanisms are still not well understood. Epigenetic modifications play a key role in the biological responses to external stressors. Therefore, this review discusses the roles of epigenetic modifications in male reproductive toxicity induced by environmental pollutants, with a particular emphasis on DNA methylation, histone modifications and miRNAs. The available literature proposed that environmental pollutants can directly or cause oxidative stress and DNA damage to induce a variety of epigenetic changes, which lead to gene dysregulation, mitochondrial dysfunction and consequent male reproductive toxicity. However, future studies focusing on more kinds of epigenetic modifications and their crosstalk as well as epidemiological data are still required to fill in the current research gaps. In addition, the intrinsic links between pollutants-mediated epigenetic regulations and male reproduction-related physiological responses deserve to be further explored.

Loss of H3K27me3 occurs in a large subset of embryonal rhabdomyosarcomas: Immunohistochemical and molecular analysis of 25 cases

Loss of histone 3 lysine 27 trimethylation (H3K27me3) has been described as a diagnostic marker for malignant peripheral nerve sheath tumor (MPNST), also discriminating MPNST with rhabdomyoblastic differentiation (malignant Triton tumor) from rhabdomyosarcoma (RMS). We studied the immunohistochemical expression of H3K27me3 in embryonal RMSs (ERMSs), performed methylation profiling in order to support the diagnosis and RNA-sequencing for comparison of the transcriptome of H3K27me3-positive and -negative cases. Of the 25 ERMS patients, 17 were males and 8 were females with an age range from 1 to 67 years (median, 6 years). None were known with neurofibromatosis type 1. One patient had Li-Fraumeni syndrome. Tumor localization included paratesticular (n = 9), genitourinary (n = 6), head/neck (n = 5), retroperitoneal (n = 4) and lower arm (n = 1). Five MPNSTs served as reference group. All ERMS had classical features including a variable spindle cell component. Immunohistochemical loss (partial or complete) of H3K27me3 was detected in 18/25 cases (72%). Based on methylation profiling, 22/22 cases were classified as ERMS. Using RNA sequencing, the ERMS group (n = 14) had a distinct gene expression profile in contrast to MPNSTs, confirming that the H3K27me3 negative ERMS cases do not represent malignant Triton tumors. When comparing H3K27me3-negative and -positive ERMSs, gene set enrichment analysis revealed differential expression of genes related to histone acetylation and normal muscle function with H3K27me3 negative ERMSs being associated with acetylation. Conclusion: Loss of H3K27me3 frequently occurs in ERMSs and correlates with H3K27 acetylation. H3K27me3 is not a suitable marker to differentiate ERMS (with spindle cell features) from malignant Triton tumor.

Epigenetic alterations and advancement of treatment in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare and heterogeneous group of clinically aggressive diseases associated with poor prognosis. Except for ALK + anaplastic large-cell lymphoma (ALCL), most peripheral T-cell lymphomas are highly malignant and have an aggressive disease course and poor clinical outcomes, with a poor remission rate and frequent relapse after first-line treatment. Aberrant epigenetic alterations play an important role in the pathogenesis and development of specific types of peripheral T-cell lymphoma, including the regulation of the expression of genes and signal transduction. The most common epigenetic alterations are DNA methylation and histone modification. Histone modification alters the level of gene expression by regulating the acetylation status of lysine residues on the promoter surrounding histones, often leading to the silencing of tumour suppressor genes or the overexpression of proto-oncogenes in lymphoma. DNA methylation refers to CpG islands, generally leading to tumour suppressor gene transcriptional silencing. Genetic studies have also shown that some recurrent mutations in genes involved in the epigenetic machinery, including TET2, IDH2-R172, DNMT3A, RHOA, CD28, IDH2, TET2, MLL2, KMT2A, KDM6A, CREBBP, and EP300, have been observed in cases of PTCL. The aberrant expression of miRNAs has also gradually become a diagnostic biomarker. These provide a reasonable molecular mechanism for epigenetic modifying drugs in the treatment of PTCL. As epigenetic drugs implicated in lymphoma have been continually reported in recent years, many new ideas for the diagnosis, treatment, and prognosis of PTCL originate from epigenetics in recent years. Novel epigenetic-targeted drugs have shown good tolerance and therapeutic effects in the treatment of peripheral T-cell lymphoma as monotherapy or combination therapy. NCCN Clinical Practice Guidelines also recommended epigenetic drugs for PTCL subtypes as second-line therapy. Epigenetic mechanisms provide new directions and therapeutic strategies for the research and treatment of peripheral T-cell lymphoma. Therefore, this paper mainly reviews the epigenetic changes in the pathogenesis of peripheral T-cell lymphoma and the advancement of epigenetic-targeted drugs in the treatment of peripheral T-cell lymphoma (PTCL).

Epigenetic Mechanisms in Canine Cancer

A plethora of data has highlighted the role of epigenetics in the development of cancer. Initiation and progression of different cancer types are associated with a variety of changes of epigenetic mechanisms, including aberrant DNA methylation, histone modifications, and miRNA expression. At the same time, advances in the available epigenetic tools allow to investigate and reverse these epigenetic changes and form the basis for the development of anticancer drugs in human oncology. Although human and canine cancer shares several common features, only recently that studies emerged investigating the epigenetic landscape in canine cancer and applying epigenetic modulators to canine cancer. This review focuses on the existing studies involving epigenetic changes in different types of canine cancer and the use of small-molecule inhibitors in canine cancer cells.

Regulating Methylation at H3K27: A Trick or Treat for Cancer Cell Plasticity

Properly timed addition and removal of histone 3 lysine 27 tri-methylation (H3K27me3) is critical for enabling proper differentiation throughout all stages of development and, likewise, can guide carcinoma cells into altered differentiation states which correspond to poor prognoses and treatment evasion. In early embryonic stages, H3K27me3 is invoked to silence genes and restrict cell fate. Not surprisingly, mutation or altered functionality in the enzymes that regulate this pathway results in aberrant methylation or demethylation that can lead to malignancy. Likewise, changes in expression or activity of these enzymes impact cellular plasticity, metastasis, and treatment evasion. This review focuses on current knowledge regarding methylation and de-methylation of H3K27 in cancer initiation and cancer cell plasticity.

Sirtuins' Deregulation in Bladder Cancer: SIRT7 Is Implicated in Tumor Progression through Epithelial to Mesenchymal Transition Promotion

Sirtuins are emerging players in cancer biology and other age-related disorders, and their putative role in bladder cancer (BlCa) remains elusive. Further understanding of disease biology may allow for generation of more effective pathway-based biomarkers and targeted therapies. Herein, we aimed to illuminate the role of sirtuins’ family in BlCa and evaluate their potential as disease biomarkers and therapeutic targets. SIRT1-7 transcripts and protein levels were evaluated in a series of primary BlCa and normal bladder mucosa tissues. SIRT7 knockdown was performed through lentiviral transduction in MGHU3, 5637 and J82 cells and its functional role was assessed. SIRT1, 2, 4 and 5 expression levels were significantly lower in BlCa, whereas SIRT6 and 7 were overexpressed, and these results were corroborated by TCGA cohort analysis. SIRT7 transcript levels were significantly decreased in muscle-invasive vs. papillary BlCa. In vitro studies showed that SIRT7 downregulation promoted cells migration and invasion. Accordingly, increased EMT markers expression and decreased E-Cadherin (CDH1) was observed in those BlCa cells. Moreover, increased EZH2 expression and H3K27^me3 deposition in E-Cadherin promoter was found in sh-SIRT7 cells. We demonstrated that sirtuins are globally deregulated in BlCa, and specifically SIRT7 downregulation is implicated in EMT, fostering BlCa invasiveness through EZH2-CDH1 axis.

Targeting DNA repair in cancer: current state and novel approaches

DNA damage response, DNA repair and genomic instability have been under study for their role in tumor initiation and progression for many years now. More recently, next-generation sequencing on cancer tissue from various patient cohorts have revealed mutations and epigenetic silencing of various genes encoding proteins with roles in these processes. These findings, together with the unequivocal role of DNA repair in therapeutic response, have fueled efforts toward the clinical exploitation of research findings. The successful example of PARP1/2 inhibitors has also supported these efforts and led to numerous preclinical and clinical trials with a large number of small molecules targeting various components involved in DNA repair singularly or in combination with other therapies. In this review, we focus on recent considerations related to DNA damage response and new DNA repair inhibition agents. We then discuss how immunotherapy can collaborate with these new drugs and how epigenetic drugs can rewire the activity of repair pathways and sensitize cancer cells to DNA repair inhibition therapies.

Overexpression of Histone H3 Lysine 27 Trimethylation Is Associated with Aggressiveness and Dedifferentiation of Thyroid Cancer

A variety of epigenetic dysregulations are observed in thyroid malignancies. EZH2, the catalytic subunit of polycomb repressive complex 2, is upregulated in advanced thyroid cancers. EZH2 can catalyze trimethylation of histone H3 at lysine 27 (H3K27me3) and contribute to transcriptional silencing of target genes. Here, we investigated the immunohistochemical expression of H3K27me3 in neoplastic and normal thyroid tissues. Normal thyroid epithelial cells typically exhibited nuclear staining of moderate intensity. A similar expression pattern was observed in nodular goiters and follicular adenomas. By contrast, strong H3K27me3 expression was evident in 80% (8/10) lymphocytic thyroiditis, 63% (80/127) papillary thyroid cancer, 41% (7/17) follicular thyroid cancer, and 73% (8/11) poorly differentiated and anaplastic thyroid cancer. In differentiated thyroid cancer, strong H3K27me3 expression was associated with extrathyroidal extension (p < 0.001), lymphovascular invasion (p = 0.029), lymph node metastasis (p = 0.006), and higher risk of recurrence (p = 0.003). Our results indicate that H3K27me3 overexpression may be implicated in aggressiveness and dedifferentiation of thyroid cancer. In addition to prognostication, the predictive value of H3K27me3 expression deserves further investigation given the recent development of epigenetic targeting agents.

Developmental Programming: Contribution of Epigenetic Enzymes to Antral Follicular Defects in the Sheep Model of PCOS

Prenatal testosterone (T)-treated sheep, similar to women with polycystic ovary syndrome (PCOS), manifest oligo-/anovulation, hyperandrogenism, and polyfollicular ovary. The polyfollicular ovarian morphology, a result of persistence of antral follicles, arises, in part, by transcriptional changes in key mediators of follicular development that, in turn, are driven by epigenetic mechanisms. We hypothesized that prenatal T excess induces, in a cell-specific manner, transcriptional changes in key mediators of follicular development associated with relevant changes in epigenetic machinery. Expression levels of key mediators of follicular development, DNA methyltransferases (DNMTs), and histone de-/methylases and de-/acetylases were determined in laser-capture microdissection-isolated antral follicular granulosa and theca and ovarian stromal cells from 21 months of age control and prenatal T-treated sheep (100 mg IM twice weekly from gestational day 30 to 90; term: 147 days). Changes in histone methylation were determined by immunofluorescence. Prenatal T treatment induced the following: (i) cell-specific changes in gene expression of key mediators of follicular development and steroidogenesis; (ii) granulosa, theca, and stromal cell-specific changes in DNMTs and histone de-/methylases and deacetylases, and (iii) increases in histone 3 trimethylation at lysine 9 in granulosa and histone 3 dimethylation at lysine 4 in theca cells. The pattern of histone methylation was consistent with the expression profile of histone de-/methylases in the respective cells. These findings suggest that changes in expression of key genes involved in the development of the polyfollicular phenotype in prenatal T-treated sheep are mediated, at least in part, by cell-specific changes in epigenetic-modifying enzymes.

A systematic review of smoking-related epigenetic alterations

The aim of this study is to provide a systematic review of the known epigenetic alterations caused by cigarette smoke; establish an evidence-based perspective of their clinical value for screening, diagnosis, and treatment of smoke-related disorders; and discuss the challenges and ethical concerns associated with epigenetic studies. A well-defined, reproducible search strategy was employed to identify relevant literature (clinical, cellular, and animal-based) between 2000 and 2019 based on AMSTAR guidelines. A total of 80 studies were identified that reported alterations in DNA methylation, histone modifications, and miRNA expression following exposure to cigarette smoke. Changes in DNA methylation were most extensively documented for genes including AHRR, F2RL3, DAPK, and p16 after exposure to cigarette smoke. Likewise, miR16, miR21, miR146, and miR222 were identified to be differentially expressed in smokers and exhibit potential as biomarkers for determining susceptibility to COPD. We also identified 22 studies highlighting the transgenerational effects of maternal and paternal smoking on offspring. This systematic review lists the epigenetic events/alterations known to occur in response to cigarette smoke exposure and identifies the major genes and miRNAs that are potential targets for translational research in associated pathologies. Importantly, the limitations and ethical concerns related to epigenetic studies are also highlighted, as are the effects on the ability to address specific questions associated with exposure to tobacco/cigarette smoke. In the future, improved interpretation of epigenetic signatures will lead to their increased use as biomarkers and/or in drug development.

Histone Methylation Participates in Gene Expression Control during the Early Development of the Pacific Oyster Crassostrea gigas

Histone methylation patterns are important epigenetic regulators of mammalian development, notably through stem cell identity maintenance by chromatin remodeling and transcriptional control of pluripotency genes. But, the implications of histone marks are poorly understood in distant groups outside vertebrates and ecdysozoan models. However, the development of the Pacific oyster Crassostrea gigas is under the strong epigenetic influence of DNA methylation, and Jumonji histone-demethylase orthologues are highly expressed during C. gigas early life. This suggests a physiological relevance of histone methylation regulation in oyster development, raising the question of functional conservation of this epigenetic pathway in lophotrochozoan. Quantification of histone methylation using fluorescent ELISAs during oyster early life indicated significant variations in monomethyl histone H3 lysine 4 (H3K4me), an overall decrease in H3K9 mono- and tri-methylations, and in H3K36 methylations, respectively, whereas no significant modification could be detected in H3K27 methylation. Early in vivo treatment with the JmjC-specific inhibitor Methylstat induced hypermethylation of all the examined histone H3 lysines and developmental alterations as revealed by scanning electronic microscopy. Using microarrays, we identified 376 genes that were differentially expressed under methylstat treatment, which expression patterns could discriminate between samples as indicated by principal component analysis. Furthermore, Gene Ontology revealed that these genes were related to processes potentially important for embryonic stages such as binding, cell differentiation and development. These results suggest an important physiological significance of histone methylation in the oyster embryonic and larval life, providing, to our knowledge, the first insights into epigenetic regulation by histone methylation in lophotrochozoan development.

Lysine methylation regulates nervous system diseases

Lysine methylation is an important dynamic modification which is essential in the epigenetic regulation of gene transcription. Unlike acetylation markers, lysine methylation signals at gene promoters could be viewed as markers that either activate or silence gene expression in different contexts or states. This article briefly reviews lysine methylation sites involved in nervous system diseases. The methyltransferases and demethylases which cause abnormal methylation signals in nervous system diseases are also discussed. Methylated proteins correlated with nervous system biological processes are extracted from databases and known writer-code-eraser patterns are analyzed, which could provide insight into the design of methylation-based interference peptides for the investigation of nervous system diseases.

Lung Cancer Therapy Targeting Histone Methylation: Opportunities and Challenges

Lung cancer is one of the most common malignancies. In spite of the progress made in past decades, further studies to improve current therapy for lung cancer are required. Dynamically controlled by methyltransferases and demethylases, methylation of lysine and arginine residues on histone proteins regulates chromatin organization and thereby gene transcription. Aberrant alterations of histone methylation have been demonstrated to be associated with the progress of multiple cancers including lung cancer. Inhibitors of methyltransferases and demethylases have exhibited anti-tumor activities in lung cancer, and multiple lead candidates are under clinical trials. Here, we summarize how histone methylation functions in lung cancer, highlighting most recent progresses in small molecular inhibitors for lung cancer treatment.

Notch-effector CSL promotes squamous cell carcinoma by repressing histone demethylase KDM6B

Notch 1/2 genes play tumor-suppressing functions in squamous cell carcinoma (SCC), a very common malignancy in skin and internal organs. In contrast with Notch, we show that the transcription factor CSL (also known as RBP-Jκ), a key effector of canonical Notch signaling endowed with intrinsic transcription-repressive functions, plays a tumor-promoting function in SCC development. Expression of this gene decreased in upper epidermal layers and human keratinocytes (HKCs) undergoing differentiation, while it increased in premalignant and malignant SCC lesions from skin, head/neck, and lung. Increased CSL levels enhanced the proliferative potential of HKCs and SCC cells, while silencing of CSL induced growth arrest and apoptosis. In vivo, SCC cells with increased CSL levels gave rise to rapidly expanding tumors, while cells with silenced CSL formed smaller and more differentiated tumors with enhanced inflammatory infiltrate. Global transcriptomic analysis of HKCs and SCC cells with silenced CSL revealed major modulation of apoptotic, cell-cycle, and proinflammatory genes. We also show that the histone demethylase KDM6B is a direct CSL-negative target, with inverse roles of CSL in HKC and SCC proliferative capacity, tumorigenesis, and tumor-associated inflammatory reaction. CSL/KDM6B protein expression could be used as a biomarker of SCC development and indicator of cancer treatment.

Identification of JL1037 as a novel, specific, reversible lysine-specific demethylase 1 inhibitor that induce apoptosis and autophagy of AML cells

Lysine-specific demethylase 1 (LSD1) has been recognized as a potential therapeutic target for acute myeloid leukemia (AML). Herein, we identified a novel LSD1 inhibitor, JL1037, via Computer Aided Drug Design technology. JL1037 is a potent, selective and reversible LSD1 inhibitor with IC50s of 0.1 μM and >1.5 μM for LSD1 and monoamine oxidases A/B (MAO-A/B), respectively. Treatment of THP-1 and Kasumi-1 cell lines with JL1037 resulted in dose dependent accumulation of H3K4me1 and H3K4me2, the major substrates of LSD1, as well as inhibition of cell proliferation, blockade of cell cycle and induction of apoptosis. Further investigations demonstrated that JL1037 could upregulate cell cycle-related proteins P21, P57, pro-apoptotic protein Bax and downregulate anti-apoptosis proteins Bcl-2 and Bcl-XL. JL1037 appeared to activate autophage response in AML cell lines as well as primary cells from AML patients by increasing LC3-II expression and the formation of autophagosomes and autolysosomes in cytoplasm. Co-treatment with autophagy inhibitor chloroquine (CQ) enhanced JL1037-induced cell apoptosis. Moreover, daily intravenous administration of JL1037 tended to reduce tumor burden and prolong the survival of t(8;21) leukemia mice. In conclusion, JL1037 exhibited potent anti-leukemia effect and could be a potential therapeutic agent for AML treatment.

Correlations of EZH2 and SMYD3 gene polymorphisms with breast cancer susceptibility and prognosis

The aim of the present study was to investigate the correlation of enhancer of Zeste homolog 2 (EZH2) and SET and MYND domain containing 3 (SMYD3) gene polymorphisms with breast cancer susceptibility and prognosis. A total of 712 patients with breast cancer and 783 healthy individuals were selected. Normal breast epithelial cells MCF-10A and breast cancer cells MCF-7, MDA-MB-231, T47D, and Bcap-37 were cultured. Polymerase chain reaction (PCR)-restriction fragment length polymorphism method was applied for genotyping. Reverse-transcription quantitative PCR (RT-qPCR) and Western blotting were used to examine EZH2 and SMYD3 expression in breast cancer tissues and cells. The risk factors and prognostic factors for breast cancer were estimated. The C allele of EZH2 rs12670401 (odds ratio (OR) =1.255, 95% confidence interval (95% CI): 1.085-1.452), T allele of EZH2 rs6464926 (OR =1.240, 95% CI: 1.071-1.435), and three alleles of SMYD3 variable number of tandem repeats (VNTRs) (OR =1.305, 95% CI: 1.097-1.552) could increase susceptibility to breast cancer. Combined genotypes of EZH2 rs12670401 (TC + CC) and EZH2 rs6464926 (CT + TT) were associated with breast cancer susceptibility. Breast cancer tissues had higher EZH2 and SMYD3 expression. EZH2 rs12670401, EZH2 rs6464926, age of menarche, and menopausal status were associated with breast cancer susceptibility. Patients with TT genotype of EZH2 rs12670401 or with CC genotype of EZH2 rs6464926 had higher overall survival (OS). EZH2 rs12670401, EZH2 rs6464926, and clinical staging were independent prognostic factors for breast cancer. SMYD3 VNTR polymorphism exhibited no association with susceptibility and prognosis. EZH2 rs12670401 and rs6464926 polymorphisms, EZH2 and SMYD3 expression, clinical staging, lymph node metastasis, human epidermal growth factor receptor-2 (HER2) status, and metastasis may be correlated with breast cancer susceptibility and prognosis.

Epigenetic Targeting of Granulin in Hepatoma Cells by Synthetic CRISPR dCas9 Epi-suppressors

The CRISPR-associated Cas9 system can modulate disease-causing alleles both in vivo and ex vivo, raising the possibility of therapeutic genome editing. In addition to gene targeting, epigenetic modulation by the catalytically inactive dCas9 may also be a potential form of cancer therapy. Granulin (GRN), a potent pluripotent mitogen and growth factor that promotes cancer progression by maintaining self-renewal of hepatic stem cancer cells, is upregulated in hepatoma tissues and is associated with decreased tumor survival in patients with hepatoma. We synthesized a group of dCas9 epi-suppressors to target GRN by tethering the C terminus of dCas9 with three epigenetic suppressor genes: DNMT3a (DNA methyltransferase), EZH2 (histone 3 lysine 27 methyltransferase), and KRAB (the Krüppel-associated box transcriptional repression domain). In conjunction with guide RNAs (gRNAs), the dCas9 epi-suppressors caused significant decreases in GRN mRNA abundance in Hep3B hepatoma cells. These dCas9 epi-suppressors initiated de novo CpG DNA methylation in the GRN promoter, and they produced histone codes that favor gene suppression, including decreased H3K4 methylation, increased H3K9 methylation, and enhanced HP1a binding. Epigenetic knockdown of GRN led to the inhibition of cell proliferation, decreased tumor sphere formation, and reduced cell invasion. These changes were achieved at least partially through the MMP/TIMP pathway. This study thus demonstrates the potential utility of using dCas9 epi-suppressors in the development of epigenetic targeting against tumors.

DISORDERED HISTONE METHYLATION IN HEMATOLOGICAL MALIGNANCIES THE CASE OF UTX/KDM6A

Alterations of epigenetic proteins that modulate the gene repressive lysine 27 on histone H3 (H3K27me) are recurrent features in cancers, including multiple myeloma (MM). The histone demethylase UTX/KDM6A, mutated in up to 10% of cases of MM activates genes by removing the H3K27me3 repressive histone mark, counteracting EZH2. RNA-sequencing studies showed that UTX upregulated genes in association with loss of H3K27me. Treatment of MM cell lines with an EZH2 inhibitor preferentially slowed growth of UTX-null cells. EZH2 inhibitors activated many of the same genes as UTX but also induced the earlier stage B cell marker Bcl6 which, in turn, shut off the late B cell IRF4 and MYC, leading to cell death.

Epigenetic regulatory mutations and epigenetic therapy for multiple myeloma

PURPOSE OF REVIEW

Next generation sequencing and large-scale analysis of patient specimens has created a more complete picture of multiple myeloma (MM) revealing that epigenetic deregulation is a prominent factor in MM pathogenesis.

RECENT FINDINGS

Over half of MM patients have mutations in genes encoding epigenetic modifier enzymes. The DNA methylation profile of MM is related to the stage of the disease and certain classes of mutations in epigenetic modifiers are more prevalent upon disease relapse, suggesting a role in disease progression. Many small molecules targeting regulators of epigenetic machinery have been developed and clinical trials are underway for some of these in MM.

SUMMARY

Recent findings suggest that epigenetic targeting drugs could be an important strategy to cure MM. Combining these agents along with other strategies to affect the MM cell such as immunomodulatory drugs and proteasome inhibitors may enhance efficacy of combination regimens in MM.

RIZ1 and histone methylation status in pituitary adenomas

RIZ1 displays strong tumor-suppressive activities, which has a potential histone methyltransferase activity. The objective of the study was to evaluate the level and the methylation status of RIZ1 and analyze its association with clinicopathological features and the histone in the pituitary adenomas. We found that RIZ1-positive cases were 11/50 and H-Scores 22.75 ± 11.83 in invasive pituitary adenomas and 26/53 and 66.3 ± 21.7 in non-invasive pituitary adenomas (χ² = 8.182, p = 0.004). RIZ1 and C-myc showed the opposite trend in these cases. The methylation levels of RIZ1 were more than 50% in 30.4% (7/23) CpG sites through MALDI-TOF Mass array. There was significant difference (p < 0.01) in 4 CpG sites between invasive pituitary adenoma group and non-invasive pituitary adenoma group; furthermore, the relieved methylation levels of H3K4/H3K9 and enhanced methylation levels of H3K27 in the patients' serum were found. Furthermore, there was statistic difference of H3K4 and H3K27 methylation between invasive pituitary adenoma and non-invasive pituitary adenoma group (p < 0.01). The average progression-free survival in high RIZ1 group was 52.63 ± 7.62 months and 26.06 ± 4.23 months in low RIZ1 group (p < 0.05). Promoter region methylation of RIZ1 may play an important role in the epigenetic silencing of RIZ1 expression in pituitary adenomas, which may translate into important diagnostic and therapeutic applications.

KDM3A promotes inhibitory cytokines secretion by participating in TLR4 regulation of Foxp3 transcription in lung adenocarcinoma cells

Toll-like receptor 4 (TLR4) is a pattern recognition receptors, a member of the Toll-like receptor family and it serves a role in innate and acquired immunity. It has previously been reported that TLR4 was overexpressed in a variety of tumor tissues and cells, including colorectal cancer, gastric cancer and ovarian cancer. In the tumor microenvironment, the TLR4 signaling pathway may be activated in order to upregulate forkhead box P3 (Foxp3) expression in regulatory T cells (Tregs), and thus enhance the immunosuppressive function of Tregs. Also, inflammatory cytokine release would be increased, which promotes tumor immune system evasion. Additionally, it has previously been reported that TLR4 activation may induce histone methylation changes at multiple sites. However, the effects of the alterations to histone methylation in the process of TLR4-associated tumor immune system evasion are not currently known. Histone methylation serves a critical role in regulating gene expression. Abnormal histone methylation is closely associated with tumor development and progression. In order to investigate the epigenetic mechanisms underlying Foxp3 regulation by TLR4, the human lung adenocarcinoma cell line A549 was used. In the present study, it was revealed that the expression level of H3K9me1/2 histone lysine demethylase 3A (KDM3A) was significantly increased following TLR 4 activation in the lung adenocarcinoma A549 cell line, whereas silencing of KDM3A expression led to significantly reduced Foxp3 expression under TLR4 regulation. This result suggests that KDM3A participates in TLR4 regulation of Foxp3 transcription. Additional analysis revealed that during nuclear transport of Foxp3, KDM3A may directly bind to the Foxp3 promoter and activate its transcription. This results in increased secretion of Foxp3-downstream inhibitory cytokines, including transforming growth factor-β1 (TGF-β1), interleukin 35 (IL-35) and heme oxygenase 1 (HO-1), which have immunosuppressive effects and ultimately facilitate the immune escape of lung cancer cells. From the results, the present study concluded that TLR4 activation promoted the expression of H3K9me1/2 demethylase KDM3A. KDM3A bound directly to the Foxp3 promoter and promoted Foxp3 transcription, thereby inducing the secretion of Foxp3-associated downstream inhibitory cytokines (TGF-β1, IL-35, and HO-1), ultimately facilitating the immune system evasion of lung adenocarcinoma.

DNA Methylation Targeting: The DNMT/HMT Crosstalk Challenge

Chromatin can adopt a decondensed state linked to gene transcription (euchromatin) and a condensed state linked to transcriptional repression (heterochromatin). These states are controlled by epigenetic modulators that are active on either the DNA or the histones and are tightly associated to each other. Methylation of both DNA and histones is involved in either the activation or silencing of genes and their crosstalk. Since DNA/histone methylation patterns are altered in cancers, molecules that target these modifications are interesting therapeutic tools. We present herein a vast panel of DNA methyltransferase inhibitors classified according to their mechanism, as well as selected histone methyltransferase inhibitors sharing a common mode of action.