Targeting Epigenetic 'Readers' with Natural Compounds for Cancer Interception

Uterine fibroids: current research on novel drug targets and innovative therapeutic strategies

INTRODUCTION

Uterine fibroids, the most common nonmalignant tumors affecting the female genital tract, are a significant medical challenge. This article focuses on the most recent studies that attempted to identify novel non-hormonal therapeutic targets and strategies in UF therapy.

AREAS COVERED

This review covers the analysis of the pharmacological and biological mechanisms of the action of natural substances and the role of the microbiome in reference to UFs. This study aimed to determine the potential role of these compounds in UF prevention and therapy.

EXPERT OPINION

While there are numerous approaches for treating UFs, available drug therapies for disease control have not been optimized yet. This review highlights the biological potential of vitamin D, EGCG and other natural compounds, as well as the microbiome, as promising alternatives in UF management and prevention. Although these substances have been quite well analyzed in this area, we still recommend conducting further studies, particularly randomized ones, in the field of therapy with these compounds or probiotics. Alternatively, as the quality of data continues to improve, we propose the consideration of their integration into clinical practice, in alignment with the patient's preferences and consent.

Unveiling Allosteric Regulation and Binding Mechanism of BRD9 through Molecular Dynamics Simulations and Markov Modeling

Bromodomain-containing protein 9 (BRD9) is a key player in chromatin remodeling and gene expression regulation, and it is closely associated with the development of various diseases, including cancers. Recent studies have indicated that inhibition of BRD9 may have potential value in the treatment of certain cancers. Molecular dynamics (MD) simulations, Markov modeling and principal component analysis were performed to investigate the binding mechanisms of allosteric inhibitor POJ and orthosteric inhibitor 82I to BRD9 and its allosteric regulation. Our results indicate that binding of these two types of inhibitors induces significant structural changes in the protein, particularly in the formation and dissolution of α-helical regions. Markov flux analysis reveals notable changes occurring in the α-helicity near the ZA loop during the inhibitor binding process. Calculations of binding free energies reveal that the cooperation of orthosteric and allosteric inhibitors affects binding ability of inhibitors to BRD9 and modifies the active sites of orthosteric and allosteric positions. This research is expected to provide new insights into the inhibitory mechanism of 82I and POJ on BRD9 and offers a theoretical foundation for development of cancer treatment strategies targeting BRD9.

A-Z of Epigenetic Readers: Targeting Alternative Splicing and Histone Modification Variants in Cancer

Epigenetic 'reader' proteins, which have evolved to interact with specific chromatin modifications, play pivotal roles in gene regulation. There is growing interest in the alternative splicing mechanisms that affect the functionality of such epigenetic readers in cancer etiology. The current review considers how deregulation of epigenetic processes and alternative splicing events contribute to pathophysiology. An A-Z guide of epigenetic readers is provided, delineating the antagonistic 'yin-yang' roles of full-length versus spliced isoforms, where this is known from the literature. The examples discussed underscore the key contributions of epigenetic readers in transcriptional regulation, early development, and cancer. Clinical implications are considered, offering insights into precision oncology and targeted therapies focused on epigenetic readers that have undergone alternative splicing events during disease pathogenesis. This review underscores the fundamental importance of alternative splicing events in the context of epigenetic readers while emphasizing the critical need for improved understanding of functional diversity, regulatory mechanisms, and future therapeutic potential.

Green Cancer Prevention and Beyond

The concept of green chemoprevention was introduced in 2012 by Drs. Jed Fahey and Thomas Kensler as whole-plant foods and/or extract-based interventions demonstrating cancer prevention activity. Refining concepts and research demonstrating proof-of-principle approaches are highlighted within this review. Early approaches included extensively investigated whole foods, including broccoli sprouts and black raspberries showing dose-responsive effects across a range of activities in both animals and humans with minimal or no apparent toxicity. A recent randomized crossover trial evaluating the detoxification of tobacco carcinogens by a broccoli seed and sprout extract in the high-risk cohort of current smokers highlights the use of a dietary supplement as a potential next-generation green chemoprevention or green cancer prevention approach. Challenges are addressed, including the selection of dose, duration and mode of delivery, choice of control group, and standardization of the plant food or extract. Identification and characterization of molecular targets and careful selection of high-risk cohorts for study are additional important considerations when designing studies. Goals for precision green cancer prevention include acquiring robust evidence from carefully controlled human studies linking plant foods, extracts, and compounds to modulation of targets for cancer risk reduction in individual cancer types.

Epigenetic regulation of cancer-associated fibroblast heterogeneity

Cancer-associated fibroblasts (CAFs), a significant component of the tumor microenvironment (TME), contribute to cancer progression through the secretion of extracellular matrix (ECM), growth factors, and metabolites. It is now well recognized that CAFs are a heterogenous population with ablation experiments leading to reduced tumor growth and single-cell RNA sequencing demonstrating CAF subgroups. CAFs lack genetic mutations yet substantially differ from their normal stromal precursors. Here, we review epigenetic changes in CAF maturation, focusing on DNA methylation and histone modifications. DNA methylation changes in CAFs have been demonstrated globally, while roles of methylation at specific genes affect tumor growth. Further, loss of CAF histone methylation and gain of histone acetylation has been shown to promote CAF activation and tumor promotion. Many CAF activating factors, such as transforming growth factor β (TGFβ), lead to these epigenetic changes. MicroRNAs (miRNAs) serve as targets and orchestrators of epigenetic modifications that influence gene expression. Bromodomain and extra-terminal domain (BET), an epigenetic reader, recognizes histone acetylation and activates the transcription of genes leading to the pro-tumor phenotype of CAFs.

BRD9 Inhibition by Natural Polyphenols Targets DNA Damage/Repair and Apoptosis in Human Colon Cancer Cells

Epigenetic mechanisms play an important role in the etiology of colorectal cancer (CRC) and other malignancies due, in part, to deregulated bromodomain (BRD) functions. Inhibitors of the bromodomain and extraterminal (BET) family have entered into clinical trials as anticancer agents, and interest has grown in other acetyl 'reader' proteins as therapeutic targets, including non-BET member bromodomain-containing protein 9 (BRD9). We report here that overexpression of BRD9 is associated with poor prognosis in CRC patients, and that siRNA-mediated knockdown of BRD9 decreased cell viability and activated apoptosis in human colon cancer cells, coincident with increased DNA damage. Seeking natural compounds as BRD9 antagonists, molecular docking in silico identified several polyphenols such as Epigallocatechin-3-gallate (EGCG), Equol, Quercetin, and Aspalathin, with favorable binding energies, supported by BROMOscan^® (DiscoverX) and isothermal titration calorimetry experiments. Polyphenols mimicked BRD9 knockdown and iBRD9 treatment in reducing colon cancer cell viability, inhibiting colony formation, and enhancing DNA damage and apoptosis. Normal colonic epithelial cells were unaffected, signifying cancer-specific effects. These findings suggest that natural polyphenols recognize and target BRD9 for inhibition, and might serve as useful lead compounds for bromodomain therapeutics in the clinical setting.

Targeting Histone Deacetylases: Opportunities for Cancer Treatment and Chemoprevention

The dysregulation of gene expression is a critical event involved in all steps of tumorigenesis. Aberrant histone and non-histone acetylation modifications of gene expression due to the abnormal activation of histone deacetylases (HDAC) have been reported in hematologic and solid types of cancer. In this sense, the cancer-associated epigenetic alterations are promising targets for anticancer therapy and chemoprevention. HDAC inhibitors (HDACi) induce histone hyperacetylation within target proteins, altering cell cycle and proliferation, cell differentiation, and the regulation of cell death programs. Over the last three decades, an increasing number of synthetic and naturally derived compounds, such as dietary-derived products, have been demonstrated to act as HDACi and have provided biological and molecular insights with regard to the role of HDAC in cancer. The first part of this review is focused on the biological roles of the Zinc-dependent HDAC family in malignant diseases. Accordingly, the small-molecules and natural products such as HDACi are described in terms of cancer therapy and chemoprevention. Furthermore, structural considerations are included to improve the HDACi selectivity and combinatory potential with other specific targeting agents in bifunctional inhibitors and proteolysis targeting chimeras. Additionally, clinical trials that combine HDACi with current therapies are discussed, which may open new avenues in terms of the feasibility of HDACi’s future clinical applications in precision cancer therapies.

Role of chemopreventive phytochemicals in NRF2-mediated redox homeostasis in humans

While functioning as a second messenger in the intracellular signaling, ROS can cause oxidative stress when produced in excess or not neutralized/eliminated properly. Excessive ROS production is implicated in multi-stage carcinogenesis. Our body is equipped with a defense system to cope with constant oxidative stress caused by the external insults, including redox-cycling chemicals, radiation, and microbial infection as well as endogenously generated ROS. The transcription factor, nuclear transcription factor erythroid 2-related factor 2 (NRF2) is a master switch in the cellular antioxidant signaling and plays a vital role in adaptive survival response to ROS-induced oxidative stress. Although NRF2 is transiently activated when cellular redox balance is challenged, this can be overwhelmed by massive oxidative stress. Therefore, it is necessary to maintain the NRF2-mediated antioxidant defense capacity at an optimal level. This review summarizes the natural NRF2 inducers/activators, especially those present in the plant-based diet, in relation to their cancer chemopreventive potential in humans. The molecular mechanisms underlying their stabilization or activation of NRF2 are also discussed.

Meeting Report: Translational Advances in Cancer Prevention Agent Development Meeting

The Division of Cancer Prevention of the National Cancer Institute (NCI) and the Office of Disease Prevention of the National Institutes of Health co-sponsored the Translational Advances in Cancer Prevention Agent Development Meeting on August 27 to 28, 2020. The goals of this meeting were to foster the exchange of ideas and stimulate new collaborative interactions among leading cancer prevention researchers from basic and clinical research; highlight new and emerging trends in immunoprevention and chemoprevention as well as new information from clinical trials; and provide information to the extramural research community on the significant resources available from the NCI to promote prevention agent development and rapid translation to clinical trials. The meeting included two plenary talks and five sessions covering the range from pre-clinical studies with chemo/immunopreventive agents to ongoing cancer prevention clinical trials. In addition, two NCI informational sessions describing contract resources for the preclinical agent development and cooperative grants for the Cancer Prevention Clinical Trials Network were also presented.

Deacetylase Plus Bromodomain Inhibition Downregulates ERCC2 and Suppresses the Growth of Metastatic Colon Cancer Cells

There is growing evidence that DNA repair factors have clinical value for cancer treatment. Nucleotide excision repair (NER) proteins, including excision repair cross-complementation group 2 (ERCC2), play a critical role in maintaining genome integrity. Here, we examined ERCC2 expression following epigenetic combination drug treatment. Attention was drawn to ERCC2 for three reasons. First, from online databases, colorectal cancer (CRC) patients exhibited significantly reduced survival when ERCC2 was overexpressed in colon tumors. Second, ERCC2 was the most highly downregulated RNA transcript in human colon cancer cells, plus Ercc2 in rat tumors, after treatment with the histone deacetylase 3 (HDAC3) inhibitor sulforaphane (SFN) plus JQ1, which is an inhibitor of the bromodomain and extraterminal domain (BET) family. Third, as reported here, RNA-sequencing of polyposis in rat colon (Pirc) polyps following treatment of rats with JQ1 plus 6-methylsulfinylhexyl isothiocyanate (6-SFN) identified Ercc2 as the most highly downregulated gene. The current work also defined promising second-generation epigenetic drug combinations with enhanced synergy and efficacy, especially in metastasis-lineage colon cancer cells cultured as 3D spheroids and xenografts. This investigation adds to the growing interest in combination approaches that target epigenetic 'readers', 'writers', and 'erasers' that are deregulated in cancer and other pathologies, providing new avenues for precision oncology and cancer interception.