The function of histone methylation and acetylation regulators in GBM pathophysiology

Epigenetic regulation of histone modifications in glioblastoma: recent advances and therapeutic insights

Glioblastoma (GBM) is the most common primary malignant brain tumor, characterized by its aggressive behavior, limited treatment options, and poor prognosis. Despite advances in surgery, radiotherapy, and chemotherapy, the median survival of GBM patients remains disappointingly short. Recent studies have underscored the critical role of histone modifications in GBM malignant progression and therapy resistance. Histones, protein components of chromatin, undergo various modifications, including acetylation and methylation. These modifications significantly affect gene expression, thereby promoting tumorigenesis and resistance to therapy. Targeting histone modifications has emerged as a promising therapeutic approach. Numerous pre-clinical studies have evaluated histone modification agents in GBM, including histone deacetylase inhibitors and histone methyltransferase inhibitors. These studies demonstrate that modulating histone modifications can alter gene expression patterns, inhibit tumor growth, induce apoptosis, and sensitize tumor cells to conventional treatments. Some agents have advanced to clinical trials, aiming to translate preclinical efficacy into clinical benefit. However, clinical outcomes remain suboptimal, as many agents fail to significantly improve GBM patient prognosis. These challenges are attributed to the complexity of histone modification networks and the adaptive responses of the tumor microenvironment. This review provides a comprehensive overview of epigenetic regulation mechanisms involving histone modifications in GBM, covering their roles in tumor development, tumor microenvironment remodeling, and therapeutic resistance. Additionally, the review discusses current clinical trials targeting histone modifications in GBM, highlighting successes, limitations, and future perspectives.

Natural products modulating epigenetic mechanisms by affecting histone methylation/demethylation: Targeting cancer cells

Many natural products can exert anticancer or chemopreventive activity by interfering with the cellular epigenetic machinery. Many studies indicate the relevance of affecting DNA methylation and histone acetylation, however the influence on the mechanisms related to histone methylation are often overlooked. This may be associated with the lagging evidence that changes in the action of histone methylation writers and erasers, and subsequent alterations in the profile of histone methylation are causally related with carcinogenesis. Recent animal studies have shown that targeting histone methylation/demethylation affects the course of experimentally induced carcinogenesis. Existing data suggest that numerous natural compounds from different chemical groups, including green tea polyphenols and other flavonoids, curcuminoids, stilbene derivatives, phenolic acids, isothiocyanates, alkaloids and terpenes, can affect the expression and activity of crucial enzymes involved in the methylation and demethylation of histone lysine and arginine residues. These activities have been associated with the modulation of cancer-related gene expression and functional changes, including reduced cell proliferation and migration, and enhanced apoptosis in various cancer models. Most studies focused on the modulation of the expression and/or activity of two proteins - EZH2 (a H3K27 methyltransferase) and LSD1 (lysine demethylase 1A - a H3K4/9 demethylase), or the effects on the global levels of histone methylation caused by the phytochemicals, but data regarding other histone methyltransferases or demethylases are scarce. While the field remains relatively unexplored, this review aims to explore the impact of natural products on the enzymes related to histone methylation/demethylation, showing their relevance to carcinogenesis and cancer progression. LINKED ARTICLES: This article is part of a themed issue Natural Products and Cancer: From Drug Discovery to Prevention and Therapy. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.10/issuetoc.

Key genes altered in glioblastoma based on bioinformatics (Review)

Glioblastoma multiforme (GBM) is an aggressive brain tumor with poor prognosis. Recent advancements in bioinformatics have contributed to uncovering the genetic alterations that underlie the development and progression of GBM. Analysis of extensive genomic data led to the identification of significant pathways involved in GBM, such as the PI3K/AKT/mTOR and Ras/Raf/MEK/ERK signaling pathways, alongside key genes such as EGFR, TP53 and TERT. These findings have enhanced our understanding of GBM biology and led to the identification of new therapeutic targets. Bioinformatics has become an indispensable tool in pinpointing the genetic modifications that drive GBM, paving the way for innovative treatment strategies. This approach not only aids in comprehending the complexities of GBM but also holds promise for improving outcomes in patients suffering from this devastating disease. The ongoing integration of bioinformatics in GBM research continues to be vital for advancing therapeutic options.

The epigenetic mechanisms involved in the treatment resistance of glioblastoma

Glioblastoma (GBM) is an aggressive malignant brain tumor with almost inevitable recurrence despite multimodal management with surgical resection and radio-chemotherapy. While several genetic, proteomic, cellular, and anatomic factors interplay to drive recurrence and promote treatment resistance, the epigenetic component remains among the most versatile and heterogeneous of these factors. Herein, the epigenetic landscape of GBM refers to a myriad of modifications and processes that can alter gene expression without altering the genetic code of cancer cells. These processes encompass DNA methylation, histone modification, chromatin remodeling, and non-coding RNA molecules, all of which have been found to be implicated in augmenting the tumor's aggressive behavior and driving its resistance to therapeutics. This review aims to delve into the underlying interactions that mediate this role for each of these epigenetic components. Further, it discusses the two-way relationship between epigenetic modifications and tumor heterogeneity and plasticity, which are crucial to effectively treat GBM. Finally, we build on the previous characterization of epigenetic modifications and interactions to explore specific targets that have been investigated for the development of promising therapeutic agents.

Hunting glioblastoma recurrence: glioma stem cells as retrospective targets

Glioblastoma (GBM) remains one of the most aggressive and treatment-resistant brain malignancies in adults. Standard approaches, including surgical resection followed by adjuvant radio- and chemotherapy with temozolomide (TMZ), provide only transient control, as GBM frequently recurs due to its infiltrative nature and the presence of therapy-resistant subpopulations such as glioma stem cells (GSCs). GSCs, with their quiescent state and robust resistance mechanisms, evade conventional therapies, contributing significantly to relapse. Consequently, current treatment methods for GBM face significant limitations in effectively targeting GSCs. In this review, we emphasize the relationship between GBM recurrence and GSCs, discuss the current limitations, and provide future perspectives to overwhelm the challenges associated with targeting GSCs. Eliminating GSCs may suppress recurrence, achieve durable responses, and improve therapeutic outcomes for patients with GBM.

ADCY5 act as a putative tumor suppressor in glioblastoma: An integrated analysis

Background

Adenylyl cyclase (AC) isoforms played a key role in the multiple cancer pathology, However, the expression, prognostic value and function of ADCY5 in Glioblastoma (GBM) have not been reported yet. This research intends to discover the expression, epigenetic alteration and biological function of ADCY5 in GBM and its value on patients' prognosis.

Methods

① Transcriptional level, epigenetic alteration, prognostic value and molecular network of ADCY5 were analyzed by using of public online datasets. ② The mRNA expression profile of ADCY5 was explored by using GEPIA database and protein expression levels were detected by HPA Database. ③ The prognostic value of ADCY5 was determined by Kaplan-Meier Plotter, GEPIA and CGGA database. ④ The epigenetic characteristics of ADCY5 were determined by DiseaseMeth database. ⑤ Identification of genes co-expressed with ADCY5 and potential mechanism analyses were performed by using DAVID cBioPorta and STRING. ⑥ Reverse transcription-polymerase chain reaction (RT-PCR), cell counting kit-8 (CCK-8), colony formation, wound-healing scratch and transwell assay were applied to detect relative mRNA expression and biological function of ADCY5 in GMB cells.

Results

ADCY5 mRNA and protein were downregulated in GBM compared with normal tissues. Analysis of the genetics and epigenetics of ADCY5 suggested that its expression was negatively correlated with DNA methylation. High expression of ADCY5 was significantly associated with age, grade, IDH mutation, 1p19q_codeletion, radiotherapy and chemotherapy and acted as an independent prognostic factor in GBM. ADCY5 mRNA also down-expressed in GBM cell lines and re-expressed of ADCY5 could inhibit cell proliferation, viability, migration/invasion and epithelial-mesenchymal transition (EMT) in vitro. In the analysis of genes co-expressed with ADCY5, we found that cAMP/AKT pathway, cGMP-PKG pathway, Wnts pathway were dissimilarly enriched.

Conclusion

Our study indicated that ADCY5 could act as an epigenetic biomarker in GBM, as well as a prognosis target in patients with GBM.

Uracil- and Pyridine-Containing HDAC Inhibitors Displayed Cytotoxicity in Colorectal and Glioblastoma Cancer Stem Cells

Cancer stem cells (CSCs) are a niche of highly tumorigenic cells featuring self-renewal, activation of pluripotency genes, multidrug resistance, and ability to cause cancer relapse. Seven HDACi (1-7), showing either hydroxamate or 2'-aminoanilide function, were tested in colorectal cancer (CRC) and glioblastoma multiforme (GBM) CSCs to determine their effects on cell proliferation, H3 acetylation levels and in-cell HDAC activity. Two uracil-based hydroxamates, 5 and 6, which differ in substitution at C5 and C6 positions of the pyrimidine ring, exhibited the greatest cytotoxicity in GBM (5) and CRC (6) CSCs, followed by the pyridine-hydroxamate 2, with 2- to 6-fold higher potency than the positive control SAHA. Finally, increased H3 acetylation as well as HDAC inhibition directly in cells by selected 2'-aminoanilide 4 and hydroxamate 5 confirmed target engagement. Further investigation will be conducted into the broad-spectrum anticancer properties of the most potent derivatives and their effects in combination with approved, conventional anticancer drugs.

Epigenetic regulation of tumor-immune symbiosis in glioma

Glioma is a type of aggressive and incurable brain tumor. Patients with glioma are highly resistant to all types of therapies, including immunotherapies. Epigenetic reprogramming is a key molecular hallmark in tumors across cancer types, including glioma. Mounting evidence highlights a pivotal role of epigenetic regulation in shaping tumor biology and therapeutic responses through mechanisms involving both glioma cells and immune cells, as well as their symbiotic interactions in the tumor microenvironment (TME). In this review, we discuss the molecular mechanisms of epigenetic regulation that impacts glioma cell biology and tumor immunity in both a cell-autonomous and non-cell-autonomous manner. Moreover, we provide an overview of potential therapeutic approaches that can disrupt epigenetic-regulated tumor-immune symbiosis in the glioma TME.

The Role of Non-Coding RNAs in Epigenetic Dysregulation in Glioblastoma Development

Glioblastoma (GBM) is a primary brain tumor arising from glial cells. The tumor is highly aggressive, the reason for which it has become the deadliest brain tumor type with the poorest prognosis. Like other cancers, it compromises molecular alteration on genetic and epigenetic levels. Epigenetics refers to changes in gene expression or cellular phenotype without the occurrence of any genetic mutations or DNA sequence alterations in the driver tumor-related genes. These epigenetic changes are reversible, making them convenient targets in cancer therapy. Therefore, we aim to review critical epigenetic dysregulation processes in glioblastoma. We will highlight the significant affected tumor-related pathways and their outcomes, such as regulation of cell cycle progression, cell growth, apoptosis, angiogenesis, cell invasiveness, immune evasion, or acquirement of drug resistance. Examples of molecular changes induced by epigenetic modifications, such as DNA epigenetic alterations, histone post-translational modifications (PTMs), and non-coding RNA (ncRNA) regulation, are highlighted. As understanding the role of epigenetic regulators and underlying molecular mechanisms in the overall pro-tumorigenic landscape of glioblastoma is essential, this literature study will provide valuable insights for establishing the prognostic or diagnostic value of various non-coding transcripts, including miRNAs.

The Spectrum of Molecular Pathways in Gliomas-An Up-to-Date Review

During the last 20 years, molecular alterations have gained increasing significance in the diagnosis and biological assessment of tumors. Gliomas represent the largest group of tumors of the central nervous system, and the main aim of this review is to present the current knowledge on molecular pathways and their alterations in gliomas. A wide range of new insights has been gained, including evidence for the involvement of the WNT pathway or the hippo pathway in the pathobiology of gliomas, indicating a broad involvement of different pathways formerly not considered to play a central role in gliomas. Even new aspects of angiogenic, apoptotic, and metabolic pathways are presented, as well as the rapidly growing field of epigenetic processes, including non-coding RNAs. The two major conclusions drawn from the present review are the distinct interconnectivity of the whole spectrum of molecular pathways and the prominent role of non-coding RNAs, especially circular RNAs, in the regulation of specific targets. All these new insights are discussed, even considering the topic of the resistance to therapy of gliomas, along with aspects that are still incompletely understood, like the role of hydroxymethylation, or even ferroptosis, in the pathobiology of gliomas.

Identification and characterization of putative biomarkers and therapeutic axis in Glioblastoma multiforme microenvironment

Non-cellular secretory components, including chemokines, cytokines, and growth factors in the tumor microenvironment, are often dysregulated, impacting tumorigenesis in Glioblastoma multiforme (GBM) microenvironment, where the prognostic significance of the current treatment remains unsatisfactory. Recent studies have demonstrated the potential of post-translational modifications (PTM) and their respective enzymes, such as acetylation and ubiquitination in GBM etiology through modulating signaling events. However, the relationship between non-cellular secretory components and post-translational modifications will create a research void in GBM therapeutics. Therefore, we aim to bridge the gap between non-cellular secretory components and PTM modifications through machine learning and computational biology approaches. Herein, we highlighted the importance of BMP1, CTSB, LOX, LOXL1, PLOD1, MMP9, SERPINE1, and SERPING1 in GBM etiology. Further, we demonstrated the positive relationship between the E2 conjugating enzymes (Ube2E1, Ube2H, Ube2J2, Ube2C, Ube2J2, and Ube2S), E3 ligases (VHL and GNB2L1) and substrate (HIF1A). Additionally, we reported the novel HAT1-induced acetylation sites of Ube2S (K211) and Ube2H (K8, K52). Structural and functional characterization of Ube2S (8) and Ube2H (1) have identified their association with protein kinases. Lastly, our results found a putative therapeutic axis HAT1-Ube2S(K211)-GNB2L1-HIF1A and potential predictive biomarkers (CTSB, HAT1, Ube2H, VHL, and GNB2L1) that play a critical role in GBM pathogenesis.