Cancer cell metabolism connects epigenetic modifications to transcriptional regulation

Sensitive Detection of Histones and γ-H2AX by Immunoblotting: Problems and Solutions

Histones and their posttranslational modifications (PTMs) are critical regulators of gene expression. Differentiation, environmental stressors, xenobiotics, and major human diseases cause significant changes in histone variants and PTMs. Western blotting is the mainstay methodology for detection of histones and their PTMs in the majority of studies. Surprisingly, despite their high abundance in cells, immunoblotting of histones typically involves loading of large protein amounts that are normally used for detection of sparse cellular proteins. We systematically examined technical factors in the Western-blotting-based detection of human histones with >30 antibodies. We found that under multiple protein transfer conditions, many histone epitopes on polyvinylidene fluoride (PVDF) membranes had a very low antibody accessibility, which was dramatically increased by the addition of a simple denaturation step. Denaturation of membrane-bound proteins also enhanced the specificity of some histone antibodies. In comparison to standard PVDF membranes, the sensitivity of histone detection on standard nitrocellulose membranes was typically much higher, which was further increased by the inclusion of the same denaturation step. Optimized protocols increased by >100-times detection sensitivity for the genotoxic marker γ-H2AX with two monoclonal antibodies. The impact of denaturation and nitrocellulose use varied for different histones, but for each histone, it was generally similar for antibodies targeting N-terminal and C-terminal regions. In summary, denaturation of membrane-bound histones strongly improves their detection by Westerns, resulting in more accurate measurements and permitting analyses with small biological samples.

Social determinants of health, the microbiome, and surgical injury

ABSTRACT

Postinjury infection continues to plague trauma and emergency surgery patients fortunate enough to survive the initial injury. Rapid response systems, massive transfusion protocols, and the development of level 1 trauma centers, among others, have improved the outcome for millions of patients worldwide. Nonetheless, despite this excellent initial care, patients still remain vulnerable to postinjury infections that can result in organ failure, prolonged critical illness, and even death. While risk factors have been identified (degree of injury, blood loss, time to definitive care, immunocompromise, etc.), they remain probabilistic, not deterministic, and do not explain outcome variability at the individual case level. Here, we assert that analysis of the social determinants of health, as reflected in the patient's microbiome composition (i.e., community structure, membership) and function (metabolomic output), may offer a "window" with which to define individual variability following traumatic injury. Given emerging knowledge in the field, a more comprehensive evaluation of biomarkers within the patient's microbiome, from stool-based microbial metabolites to those in plasma and those present in exhaled breath, when coupled with clinical metadata and machine learning, could lead to a more deterministic assessment of an individual's risk for a poor outcome and those factors that are modifiable. The aim of this piece is to examine how measurable elements of the social determinants of health and the life history of the patient may be buried within the ecologic memory of the gut microbiome. Here we posit that interrogation of the gut microbiome in this manner may be used to inform novel approaches to drive recovery following a surgical injury.

A prismatic view of the epigenetic-metabolic regulatory axis in breast cancer therapy resistance

Epigenetic regulation established during development to maintain patterns of transcriptional expression and silencing for metabolism and other fundamental cell processes can be reprogrammed in cancer, providing a molecular mechanism for persistent alterations in phenotype. Metabolic deregulation and reprogramming are thus an emerging hallmark of cancer with opportunities for molecular classification as a critical preliminary step for precision therapeutic intervention. Yet, acquisition of therapy resistance against most conventional treatment regimens coupled with tumor relapse, continue to pose unsolved problems for precision healthcare, as exemplified in breast cancer where existing data informs both cancer genotype and phenotype. Furthermore, epigenetic reprograming of the metabolic milieu of cancer cells is among the most crucial determinants of therapeutic resistance and cancer relapse. Importantly, subtype-specific epigenetic-metabolic interplay profoundly affects malignant transformation, resistance to chemotherapy, and response to targeted therapies. In this review, we therefore prismatically dissect interconnected epigenetic and metabolic regulatory pathways and then integrate them into an observable cancer metabolism-therapy-resistance axis that may inform clinical intervention. Optimally coupling genome-wide analysis with an understanding of metabolic elements, epigenetic reprogramming, and their integration by metabolic profiling may decode missing molecular mechanisms at the level of individual tumors. The proposed approach of linking metabolic biochemistry back to genotype, epigenetics, and phenotype for specific tumors and their microenvironment may thus enable successful mechanistic targeting of epigenetic modifiers and oncometabolites despite tumor metabolic heterogeneity.

Glutamine-mediated epigenetic regulation of cFLIP underlies resistance to TRAIL in pancreatic cancer

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent because it kills cancer cells while sparing normal cells. However, many cancers, including pancreatic ductal adenocarcinoma (PDAC), exhibit intrinsic or acquired resistance to TRAIL, and the molecular mechanisms underlying TRAIL resistance in cancers, particularly in PDAC, remain unclear. In this study, we demonstrated that glutamine (Gln) endows PDAC cells with resistance to TRAIL through KDM4C-mediated epigenetic regulation of cFLIP. Inhibition of glutaminolysis significantly reduced the cFLIP level, leading to TRAIL-mediated formation of death-inducing signaling complexes. Overexpression of cFLIP dramatically rescued PDAC cells from TRAIL/Gln deprivation-induced apoptosis. Alpha-Ketoglutarate (aKG) supplementation significantly reversed the decrease in the cFLIP level induced by glutaminolysis inhibition and rescued PDAC cells from TRAIL/Gln deprivation-induced apoptosis. Knockdown of glutamic-oxaloacetic transaminase 2, which facilitates the conversion of oxaloacetate and glutamate into aspartate and aKG, decreased aKG production and the cFLIP level and activated TRAIL-induced apoptosis. AKG-mediated epigenetic regulation was necessary for maintaining a high level of cFLIP. Glutaminolysis inhibition increased the abundance of H3K9me3 in the cFLIP promoter, indicating that Gln-derived aKG production is important for Jumonji-domain histone demethylase (JHDM)-mediated cFLIP regulation. The JHDM KDM4C regulated cFLIP expression by binding to its promoter, and KDM4C knockdown sensitized PDAC cells to TRAIL-induced apoptosis. The present findings suggest that Gln-derived aKG production is required for KDM4C-mediated epigenetic regulation of cFLIP, which leads to resistance to TRAIL.

Glutamine Supplementation as an Anticancer Strategy: A Potential Therapeutic Alternative to the Convention

Glutamine, a multifaceted nonessential/conditionally essential amino acid integral to cellular metabolism and immune function, holds pivotal importance in the landscape of cancer therapy. This review delves into the intricate dynamics surrounding both glutamine antagonism strategies and glutamine supplementation within the context of cancer treatment, emphasizing the critical role of glutamine metabolism in cancer progression and therapy. Glutamine antagonism, aiming to disrupt tumor growth by targeting critical metabolic pathways, is challenged by the adaptive nature of cancer cells and the complex metabolic microenvironment, potentially compromising its therapeutic efficacy. In contrast, glutamine supplementation supports immune function, improves gut integrity, alleviates treatment-related toxicities, and improves patient well-being. Moreover, recent studies highlighted its contributions to epigenetic regulation within cancer cells and its potential to bolster anti-cancer immune functions. However, glutamine implementation necessitates careful consideration of potential interactions with ongoing treatment regimens and the delicate equilibrium between supporting normal cellular function and promoting tumorigenesis. By critically assessing the implications of both glutamine antagonism strategies and glutamine supplementation, this review aims to offer comprehensive insights into potential therapeutic strategies targeting glutamine metabolism for effective cancer management.

Histone Acyl Code in Precision Oncology: Mechanistic Insights from Dietary and Metabolic Factors

Cancer etiology involves complex interactions between genetic and non-genetic factors, with epigenetic mechanisms serving as key regulators at multiple stages of pathogenesis. Poor dietary habits contribute to cancer predisposition by impacting DNA methylation patterns, non-coding RNA expression, and histone epigenetic landscapes. Histone post-translational modifications (PTMs), including acyl marks, act as a molecular code and play a crucial role in translating changes in cellular metabolism into enduring patterns of gene expression. As cancer cells undergo metabolic reprogramming to support rapid growth and proliferation, nuanced roles have emerged for dietary- and metabolism-derived histone acylation changes in cancer progression. Specific types and mechanisms of histone acylation, beyond the standard acetylation marks, shed light on how dietary metabolites reshape the gut microbiome, influencing the dynamics of histone acyl repertoires. Given the reversible nature of histone PTMs, the corresponding acyl readers, writers, and erasers are discussed in this review in the context of cancer prevention and treatment. The evolving 'acyl code' provides for improved biomarker assessment and clinical validation in cancer diagnosis and prognosis.

Mitochondrial Alpha-Keto Acid Dehydrogenase Complexes: Recent Developments on Structure and Function in Health and Disease

The present work delves into the enigmatic world of mitochondrial alpha-keto acid dehydrogenase complexes discussing their metabolic significance, enzymatic operation, moonlighting activities, and pathological relevance with links to underlying structural features. This ubiquitous family of related but diverse multienzyme complexes is involved in carbohydrate metabolism (pyruvate dehydrogenase complex), the citric acid cycle (α-ketoglutarate dehydrogenase complex), and amino acid catabolism (branched-chain α-keto acid dehydrogenase complex, α-ketoadipate dehydrogenase complex); the complexes all function at strategic points and also participate in regulation in these metabolic pathways. These systems are among the largest multienzyme complexes with at times more than 100 protein chains and weights ranging up to ~10 million Daltons. Our chapter offers a wealth of up-to-date information on these multienzyme complexes for a comprehensive understanding of their significance in health and disease.

An Update on Potential Molecular Biomarkers of Dietary Phytochemicals Targeting Lung Cancer Interception and Prevention

Since ancient times, dietary phytochemicals are known for their medicinal properties. They are broadly classified into polyphenols, terpenoids, alkaloids, phytosterols, and organosulfur compounds. Currently, there is considerable interest in their potential health effects against various diseases, including lung cancer. Lung cancer is the leading cause of cancer deaths with an average of five-year survival rate of lung cancer patients limited to just 14%. Identifying potential early molecular biomarkers of pre-malignant lung cancer cells may provide a strong basis to develop early cancer detection and interception methods. In this review, we will discuss molecular changes, including genetic alterations, inflammation, signal transduction pathways, redox imbalance, epigenetic and proteomic signatures associated with initiation and progression of lung carcinoma. We will also highlight molecular targets of phytochemicals during lung cancer development. These targets mainly consist of cellular signaling pathways, epigenetic regulators and metabolic reprogramming. With growing interest in natural products research, translation of these compounds into new cancer prevention approaches to medical care will be urgently needed. In this context, we will also discuss the overall pharmacokinetic challenges of phytochemicals in translating to humans. Lastly, we will discuss clinical trials of phytochemicals in lung cancer patients.

Secretion of acetylated amino acids by drug-induced cancer cells: perspectives on metabolic-epigenetic alterations

The emerging understanding of the super-complex and heterogeneous nature of tumor is well supported by metabolic reprogramming, leading survival advantages. Metabolic reprogramming contributes to tumor responsiveness and resistance to various antitumor drugs. Among the numerous adaptations made by cancer cells in response to drug-induced perturbations, key metabolic alterations involving amino acids and acetylated derivatives of amino acids have received special attention. Considering these implications discussed, targeting cancer-associated metabolic pathways, particularly those involving acetylated amino acids, emerges as an important avenue in the pursuit of combinatorial anticancer strategies. As a result, the introduction of mimetic acetylated amino acids represents a promising new class of inhibitors that could be used alongside traditional chemotherapy agents.

The role of metabolism in cellular quiescence

Cellular quiescence is a dormant, non-dividing cell state characterized by significant shifts in physiology and metabolism. Quiescence plays essential roles in a wide variety of biological processes, ranging from microbial sporulation to human reproduction and wound repair. Moreover, when the regulation of quiescence is disrupted, it can drive cancer growth and compromise tissue regeneration after injury. In this Review, we examine the dynamic changes in metabolism that drive and support dormant and transiently quiescent cells, including spores, oocytes and adult stem cells. We begin by defining quiescent cells and discussing their roles in key biological processes. We then examine metabolic factors that influence cellular quiescence in both healthy and disease contexts, and how these could be leveraged in the treatment of cancer.

Co-inhibition of glutaminolysis and one-carbon metabolism promotes ROS accumulation leading to enhancement of chemotherapeutic efficacy in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most aggressive tumors with an extremely poor prognosis. Based on the several biological features related to glutamine metabolism in ATC, we hypothesized glutaminolysis inhibition induces cell death in ATC cells. However, glutamine metabolism inhibition triggered cell growth arrest independent of cell death in ATC, suggesting that other signaling pathways avoid glutamine metabolism inhibition-induced stress exist. To investigate the functional mechanism against glutamine metabolism inhibition, we conducted mRNA and ATAC-Sequencing data analysis and found that glutamine deprivation increased ATF4-mediated one-carbon metabolism. When we inhibited PHGDH, the first rate-limiting enzyme for one-carbon metabolism, cell growth arrest was promoted upon glutamine metabolism inhibition by accumulating intracellular ROS. We next observed that the co-inhibition of glutamine and one-carbon metabolism could augment the anticancer effects of drugs used in patients with ATC. Finally, single-cell RNA sequencing analysis revealed that one-carbon metabolism was strengthened through the evolutionary process from PTC to ATC. Collectively, our data demonstrate that one-carbon metabolism has a potential role of modulation of cell fate in metabolic stress and can be a therapeutic target for enhancing antitumor effects in ATC.

Learning from cancer to address COVID-19

Patients with cancer have been disproportionately affected by the novel coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Knowledge collected during the last three decades of cancer research has helped the medical research community worldwide to respond to many of the challenges raised by COVID-19, during the pandemic. The review, briefly summarizes the underlying biology and risk factors of COVID-19 and cancer, and aims to present recent evidence on cellular and molecular relationship between the two diseases, with a focus on those that are related to the hallmarks of cancer and uncovered in the first less than three years of the pandemic (2020-2022). This may not only help answer the question "Why cancer patients are considered to be at a particularly high risk of developing severe COVID-19 illness?", but also helped treatments of patients during the COVID-19 pandemic. The last session highlights the pioneering mRNA studies and the breakthrough discovery on nucleoside-modifications of mRNA by Katalin Karikó, which led to the innovation and development of the mRNA-based SARSCoV-2 vaccines saving lives of millions and also opened the door for a new era of vaccines and a new class of therapeutics.

Nicotinamide N-methyltransferase sustains a core epigenetic program that promotes metastatic colonization in breast cancer

Metastatic colonization of distant organs accounts for over 90% of deaths related to solid cancers, yet the molecular determinants of metastasis remain poorly understood. Here, we unveil a mechanism of colonization in the aggressive basal-like subtype of breast cancer that is driven by the NAD+ metabolic enzyme nicotinamide N-methyltransferase (NNMT). We demonstrate that NNMT imprints a basal genetic program into cancer cells, enhancing their plasticity. In line, NNMT expression is associated with poor clinical outcomes in patients with breast cancer. Accordingly, ablation of NNMT dramatically suppresses metastasis formation in pre-clinical mouse models. Mechanistically, NNMT depletion results in a methyl overflow that increases histone H3K9 trimethylation (H3K9me3) and DNA methylation at the promoters of PR/SET Domain-5 (PRDM5) and extracellular matrix-related genes. PRDM5 emerged in this study as a pro-metastatic gene acting via induction of cancer-cell intrinsic transcription of collagens. Depletion of PRDM5 in tumor cells decreases COL1A1 deposition and impairs metastatic colonization of the lungs. These findings reveal a critical activity of the NNMT-PRDM5-COL1A1 axis for cancer cell plasticity and metastasis in basal-like breast cancer.

Computational design of a chimeric toxin against Claudin-4-expressing cancer cells: molecular modeling, docking and molecular dynamics simulation analysis

Cancer is one of the main reasons of mortality all over the world. Over the time, the major ways for cancer-therapy were based on radiotherapy, chemotherapy and surgery. These methods are not specific enough for that purpose, therefore, new ideas for design of new drugs with higher specificity are considered. Chimeric protein toxins are hybrid proteins consisting of a targeting portion and a toxic one which specifically bind and kill the target cancer cells. The main purpose of this study was designing a recombinant chimeric toxin with biding capability to one of the most key receptors namely claudin-4 which is over-expressed in almost all cancer cells. To design it, we utilized the last 30 C-terminal amino acids of Clostridium perfringens enterotoxin (CPE) as a binding module for claudin-4 and the toxic module which is the A-domain of Shiga toxin from Shigella dysenteriae. Using molecular modeling and docking methods, appropriate binding affinity of the recombinant chimeric toxin to its specific receptor was demonstrated. In the next step, the stability of this interaction was investigated by molecular dynamics simulation. Although partial instability was detected at some time points, however, sufficient stable situation of hydrogens bonds and high binding affinity between the chimeric toxin and receptor were observed in the in silico studies which in turn suggested that this complex could be formed successfully.

RGS proteins and their roles in cancer: friend or foe?

As negative modulators of G-protein-coupled receptors (GPCRs) signaling, regulators of G protein signaling (RGS) proteins facilitate various downstream cellular signalings through regulating kinds of heterotrimeric G proteins by stimulating the guanosine triphosphatase (GTPase) activity of G-protein α (Gα) subunits. The expression of RGS proteins is dynamically and precisely mediated by several different mechanisms including epigenetic regulation, transcriptional regulation -and post-translational regulation. Emerging evidence has shown that RGS proteins act as important mediators in controlling essential cellular processes including cell proliferation, survival -and death via regulating downstream cellular signaling activities, indicating that RGS proteins are fundamentally involved in sustaining normal physiological functions and dysregulation of RGS proteins (such as aberrant expression of RGS proteins) is closely associated with pathologies of many diseases such as cancer. In this review, we summarize the molecular mechanisms governing the expression of RGS proteins, and further discuss the relationship of RGS proteins and cancer.

Regulation of Autophagy via Carbohydrate and Lipid Metabolism in Cancer

Metabolic changes are an important component of tumor cell progression. Tumor cells adapt to environmental stresses via changes to carbohydrate and lipid metabolism. Autophagy, a physiological process in mammalian cells that digests damaged organelles and misfolded proteins via lysosomal degradation, is closely associated with metabolism in mammalian cells, acting as a meter of cellular ATP levels. In this review, we discuss the changes in glycolytic and lipid biosynthetic pathways in mammalian cells and their impact on carcinogenesis via the autophagy pathway. In addition, we discuss the impact of these metabolic pathways on autophagy in lung cancer.

Targeting Epigenetic Mechanisms: A Boon for Cancer Immunotherapy

Immunotherapy is rapidly emerging as a promising approach against cancer. In the last decade, various immunological mechanisms have been targeted to induce an increase in the immune response against cancer cells. However, despite promising results, many patients show partial response, resistance, or serious toxicities. A promising way to overcome this is the use of immunotherapeutic approaches, in combination with other potential therapeutic approaches. Aberrant epigenetic modifications play an important role in carcinogenesis and its progression, as well as in the functioning of immune cells. Thus, therapeutic approaches targeting aberrant epigenetic mechanisms and the immune response might provide an effective antitumor effect. Further, the recent development of potent epigenetic drugs and immunomodulators gives hope to this combinatorial approach. In this review, we summarize the synergy mechanism between epigenetic therapies and immunotherapy for the treatment of cancer, and discuss recent advancements in the translation of this approach.

Deregulated transcription factors in cancer cell metabolisms and reprogramming

Metabolic reprogramming is an important cancer hallmark that plays a key role in cancer malignancies and therapy resistance. Cancer cells reprogram the metabolic pathways to generate not only energy and building blocks but also produce numerous key signaling metabolites to impact signaling and epigenetic/transcriptional regulation for cancer cell proliferation and survival. A deeper understanding of the mechanisms by which metabolic reprogramming is regulated in cancer may provide potential new strategies for cancer targeting. Recent studies suggest that deregulated transcription factors have been observed in various human cancers and significantly impact metabolism and signaling in cancer. In this review, we highlight the key transcription factors that are involved in metabolic control, dissect the crosstalk between signaling and transcription factors in metabolic reprogramming, and offer therapeutic strategies targeting deregulated transcription factors for cancer treatment.

Metaboloepigenetics in cancer, immunity and cardiovascular disease

The influence of cellular metabolism on epigenetic pathways are well documented but misunderstood. Scientists have long known of the metabolic impact on epigenetic determinants. More often than not, that title role for DNA methylation was portrayed by the metabolite SAM or S-adenosylmethionine. Technically speaking there are many other metabolites that drive epigenetic processes that instruct seemingly distant - yet highly connect pathways - and none more so than our understanding of the cancer epigenome. Recent studies have shown that available energy link the extracellular environment to influence cellular responses. This focused review examines the recent interest in epigenomics and casts cancer, metabolism and immunity in unfamiliar roles - cooperating. There are not only language lessons from cancer research, we have come round to appreciate that reaching into areas previously thought of as too distinct are also object lessons in understanding health and disease. The Warburg effect is one such signature of how glycolysis influences metabolic shift during oncogenesis. That shift in metabolism - now recognised as central to proliferation in cancer biology - influence core enzymes that not only control gene expression but are also central to replication, condensation and the repair of nucleic acid. These nuclear processes rely on metabolism and with glucose at center stage the role of respiration and oxidative metabolism are now synonymous with the mitochondria as the powerhouses of metaboloepigenetics. The emerging evidence for metaboloepigenetics in trained innate immunity has revealed recognisable signalling pathways with antecedent extracellular stimulation. With due consideration to immunometabolism we discuss the striking signalling similarities influencing these core pathways. The immunometabolic-epigenetic axis in cardiovascular disease has deeply etched connections with inflammation and we examine the chromatin template as a carrier of epigenetic indices that determine the expression of genes influencing atherosclerosis and vascular complications of diabetes.

Exploiting the tumor immune microenvironment and immunometabolism using mitochondria-targeted drugs: Challenges and opportunities in racial disparity and cancer outcome research

Black and Hispanic cancer patients have a higher incidence of cancer mortality. Many factors (e.g., socioeconomic differences, insufficient access to healthcare) contribute to racial disparity. Emerging research implicates biological disparity in cancer outcomes. Studies show distinct differences in the tumor immune microenvironment (TIME) in Black cancer patients. Studies also have linked altered mitochondrial metabolism to changes in immune cell activation in TIME. Recent publications revealed a novel immunomodulatory role for triphenylphosphonium-based mitochondrial-targeted drugs (MTDs). These are synthetically modified, naturally occurring molecules (e.g., honokiol, magnolol, metformin) or FDA-approved small molecule drugs (e.g., atovaquone, hydroxyurea). Modifications involve conjugating the parent molecule via an alkyl linker chain to a triphenylphosphonium moiety. These modified molecules (e.g., Mito-honokiol, Mito-magnolol, Mito-metformin, Mito-atovaquone, Mito-hydroxyurea) accumulate in tumor cell mitochondria more effectively than in normal cells and inhibit mitochondrial respiration, induce reactive oxygen species, activate AMPK and redox transcription factors, and inhibit cancer cell proliferation. Besides these intrinsic effects of MTDs in redox signaling and proliferation in tumors, MTDs induced extrinsic effects in the TIME of mouse xenografts. MTD treatment inhibited tumor-suppressive immune cells, myeloid-derived suppressor cells, and regulatory T cells, and activated T cells and antitumor immune effects. One key biological disparity in Black cancer patients was related to altered mitochondrial oxidative metabolism; MTDs targeting vulnerabilities in tumor cells and the TIME may help us understand this biological disparity. Clinical trials should include an appropriate number of Black and Hispanic cancer patients and should validate the intratumoral, antihypoxic effects of MTDs with imaging.

Tobacco carcinogen 4-[methyl(nitroso)amino]-1-(3-pyridinyl)-1-butanone (NNK) drives metabolic rewiring and epigenetic reprograming in A/J mice lung cancer model and prevention with diallyl sulphide (DAS)

Early detection of biomarkers in lung cancer is one of the best preventive strategies. Although many attempts have been made to understand the early events of lung carcinogenesis including cigarette smoking (CS) induced lung carcinogenesis, the integrative metabolomics and next-generation sequencing approaches are lacking. In this study, we treated the female A/J mice with CS carcinogen 4-[methyl(nitroso)amino]-1-(3-pyridinyl)-1-butanone (NNK) and naturally occurring organosulphur compound, diallyl sulphide (DAS) for 2 and 4 weeks after NNK injection and examined the metabolomic and DNA CpG methylomic and RNA transcriptomic profiles in the lung tissues. NNK drives metabolic changes including mitochondrial tricarboxylic acid (TCA) metabolites and pathways including Nicotine and its derivatives like nicotinamide and nicotinic acid. RNA-seq analysis and Reactome pathway analysis demonstrated metabolism pathways including Phase I and II drug metabolizing enzymes, mitochondrial oxidation and signaling kinase activation pathways modulated in a sequential manner. DNA CpG methyl-seq analyses showed differential global methylation patterns of lung tissues from week 2 versus week 4 in A/J mice including Adenylate Cyclase 6 (ADCY6), Ras-related C3 botulinum toxin substrate 3 (Rac3). Oral DAS treatment partially reversed some of the mitochondrial metabolic pathways, global methylation and transcriptomic changes during this early lung carcinogenesis stage. In summary, our result provides insights into CS carcinogen NNK's effects on driving alterations of metabolomics, epigenomics and transcriptomics and the chemopreventive effect of DAS in early stages of sequential lung carcinogenesis in A/J mouse model.

Cancer epigenetics: promises and pitfalls for cancer therapy

Over the past few decades, epigenetic regulators have emerged as major players in cellular processes that drive cancer initiation and progression, and subsequently modulate the responsiveness of cancers to therapeutic agents. This Special Issue of The FEBS Journal, Cancer Epigenetics, features an exciting collection of review articles that focus on the functions of a broad spectrum of epigenetic modulators in cancer. The diverse topics explored herein range from the roles of transposable elements and chromatin architecture in cancer and the most recent research advances on cancer-associated histone variants (oncohistones), to the effects of altered epigenetics on transcription and advanced cancer cell phenotypes. Moreover, the prospective key function of cancer metabolism in linking epigenetics and transcriptional regulation, and the potential of epigenetics for targeted cancer therapeutics is discussed. We hope that this collection of articles will give readers an enlightening overview of the most recent advances in the fast-moving field of cancer epigenetics.

Dissecting Tumor Growth: The Role of Cancer Stem Cells in Drug Resistance and Recurrence

Simple Summary

Cancer is one of the most debated problems all over the world. Cancer stem cells are considered responsible of tumor initiation, metastasis, drug resistance, and recurrence. This subpopulation of cells has been found into the tumor bulk and showed the capacity to self-renew, differentiate, up to generate a new tumor. In the last decades, several studies have been set on the molecular mechanisms behind their specific characteristics as the Wnt/β-catenin signaling, Notch signaling, Hedgehog signaling, transcription factors, etc. The most powerful part of CSCs is represented by the niches as “promoter” of their self-renewal and “protector” from the common oncological treatment as chemotherapy and radiotherapy. In our review article we highlighted the primary mechanisms involved in CSC tumorigenesis for the setting of further targets to control the metastatic process.

Abstract

Emerging evidence suggests that a small subpopulation of cancer stem cells (CSCs) is responsible for initiation, progression, and metastasis cascade in tumors. CSCs share characteristics with normal stem cells, i.e., self-renewal and differentiation potential, suggesting that they can drive cancer progression. Consequently, targeting CSCs to prevent tumor growth or regrowth might offer a chance to lead the fight against cancer. CSCs create their niche, a specific area within tissue with a unique microenvironment that sustains their vital functions. Interactions between CSCs and their niches play a critical role in regulating CSCs’ self-renewal and tumorigenesis. Differences observed in the frequency of CSCs, due to the phenotypic plasticity of many cancer cells, remain a challenge in cancer therapeutics, since CSCs can modulate their transcriptional activities into a more stem-like state to protect themselves from destruction. This plasticity represents an essential step for future therapeutic approaches. Regarding self-renewal, CSCs are modulated by the same molecular pathways found in normal stem cells, such as Wnt/β-catenin signaling, Notch signaling, and Hedgehog signaling. Another key characteristic of CSCs is their resistance to standard chemotherapy and radiotherapy treatments, due to their capacity to rest in a quiescent state. This review will analyze the primary mechanisms involved in CSC tumorigenesis, with particular attention to the roles of CSCs in tumor progression in benign and malignant diseases; and will examine future perspectives on the identification of new markers to better control tumorigenesis, as well as dissecting the metastasis process.

Fatty Acid Synthase-Suppressor Screening Identifies Sorting Nexin 8 as a Therapeutic Target for NAFLD

BACKGROUND AND AIMS

NAFLD is the most prevalent chronic liver disease without any Food and Drug Administration-approved pharmacological intervention in clinic. Fatty acid synthase (FASN) is one of the most attractive targets for NAFLD treatment because of its robust rate-limiting capacity to control hepatic de novo lipogenesis. However, the regulatory mechanisms of FASN in NAFLD and potential therapeutic strategies targeting FASN remain largely unknown.

METHODS AND RESULTS

Through a systematic interactomics analysis of FASN-complex proteins, we screened and identified sorting nexin 8 (SNX8) as a binding partner of FASN. SNX8 directly bound to FASN and promoted FASN ubiquitination and subsequent proteasomal degradation. We further demonstrated that SNX8 mediated FASN protein degradation by recruiting the E3 ligase tripartite motif containing 28 (TRIM28) and enhancing the TRIM28-FASN interaction. Notably, Snx8 interference in hepatocytes significantly deteriorated lipid accumulation in vitro, whereas SNX8 overexpression markedly blocked hepatocyte lipid deposition. Furthermore, the aggravating effect of Snx8 deletion on NAFLD was validated in vivo as hepatic steatosis and lipogenic pathways in the liver were significantly exacerbated in Snx8-knockout mice compared to wild-type controls. Consistently, hepatocyte-specific overexpression of Snx8 in vivo markedly suppressed high-fat, high-cholesterol diet (HFHC)-induced hepatic steatosis. Notably, the protective effect of SNX8 against NAFLD was largely dependent on FASN suppression.

CONCLUSIONS

These data indicate that SNX8 is a key suppressor of NAFLD that promotes FASN proteasomal degradation. Targeting the SNX8-FASN axis is a promising strategy for NAFLD prevention and treatment.