SIRT1 Regulates N6 -Methyladenosine RNA Modification in Hepatocarcinogenesis by Inducing RANBP2-Dependent FTO SUMOylation

SUMOylation modification of FTO facilitates oxidative damage response of arsenic by IGF2BP3 in an m6A-dependent manner

N6-methyladenosine (m6A) is the most common form of internal post-transcriptional methylation observed in eukaryotic mRNAs. The abnormally increased level of m6A within the cells can be catalyzed by specific demethylase fat mass and obesity-associated protein (FTO) and stay in a dynamic and reversible state. However, whether and how FTO regulates oxidative damage via m6A modification remain largely unclear. Herein, by using both in vitro and in vivo models of oxidative damage induced by arsenic, we demonstrated for the first time that exposure to arsenic caused a significant increase in SUMOylation of FTO protein, and FTO SUMOylation at lysine (K)- 216 site promoted the down-regulation of FTO expression in arsenic target organ lung, and therefore, remarkably elevating the oxidative damage via an m6A-dependent pathway by its specific m6A reader insulin-like growth factor-2 mRNA-binding protein-3 (IGF2BP3). Consequently, these findings not only reveal a novel mechanism underlying FTO-mediated oxidative damage from the perspective of m6A, but also imply that regulation of FTO SUMOylation may serve as potential approach for treatment of oxidative damage.

Regulations of m6A and other RNA modifications and their roles in cancer

RNA modification is an essential component of the epitranscriptome, regulating RNA metabolism and cellular functions. Several types of RNA modifications have been identified to date; they include N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N6,2'-O-dimethyladenosine (m6Am), N4-acetylcytidine (ac4C), etc. RNA modifications, mediated by regulators including writers, erasers, and readers, are associated with carcinogenesis, tumor microenvironment, metabolic reprogramming, immunosuppression, immunotherapy, chemotherapy, etc. A novel perspective indicates that regulatory subunits and post-translational modifications (PTMs) are involved in the regulation of writer, eraser, and reader functions in mediating RNA modifications, tumorigenesis, and anticancer therapy. In this review, we summarize the advances made in the knowledge of different RNA modifications (especially m6A) and focus on RNA modification regulators with functions modulated by a series of factors in cancer, including regulatory subunits (proteins, noncoding RNA or peptides encoded by long noncoding RNA) and PTMs (acetylation, SUMOylation, lactylation, phosphorylation, etc.). We also delineate the relationship between RNA modification regulator functions and carcinogenesis or cancer progression. Additionally, inhibitors that target RNA modification regulators for anticancer therapy and their synergistic effect combined with immunotherapy or chemotherapy are discussed.

RNA epigenetic modifications in digestive tract cancers: Friends or foes

Digestive tract cancers are among the most common malignancies worldwide and have high incidence and mortality rates. Thus, the discovery of more effective diagnostic and therapeutic targets is urgently required. The development of technologies to accurately detect RNA modification has led to the identification of numerous RNA chemical modifications in humans (epitranscriptomics) that are involved in the occurrence and development of digestive tract cancers. RNA modifications can cooperatively regulate gene expression to facilitate normal physiological functions of the digestive system. However, the dysfunction of relevant RNA-modifying enzymes ("writers," "erasers," and "readers") can lead to the development of digestive tract cancers. Consequently, targeting dysregulated enzyme activity could represent a potent therapeutic strategy for the treatment of digestive tract cancers. In this review, we summarize the most widely studied roles and mechanisms of RNA modifications (m6A, m1A, m5C, m7G, A-to-I editing, pseudouridine [Ψ]) in relation to digestive tract cancers, highlight the crosstalk between RNA modifications, and discuss their roles in the interactions between the digestive system and microbiota during carcinogenesis. The clinical significance of novel therapeutic methods based on RNA-modifying enzymes is also discussed. This review will help guide future research into digestive tract cancers that are resistant to current therapeutics.

New horizons for the role of RNA N6-methyladenosine modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancy, presenting a formidable challenge to the medical community owing to its intricate pathogenic mechanisms. Although current prevention, surveillance, early detection, diagnosis, and treatment have achieved some success in preventing HCC and controlling overall disease mortality, the imperative to explore novel treatment modalities for HCC remains increasingly urgent. Epigenetic modification has emerged as pivotal factors in the etiology of cancer. Among these, RNA N6-methyladenosine (m6A) modification stands out as one of the most prevalent, abundant, and evolutionarily conserved post-transcriptional alterations in eukaryotes. The literature underscores that the dynamic and reversible nature of m6A modifications orchestrates the intricate regulation of gene expression, thereby exerting a profound influence on cell destinies. Increasing evidence has substantiated conspicuous fluctuations in m6A modification levels throughout the progression of HCC. The deliberate modulation of m6A modification levels through molecular biology and pharmacological interventions has been demonstrated to exert a discernible impact on the pathogenesis of HCC. In this review, we elucidate the multifaceted biological functions of m6A modifications in HCC, and concurrently advancing novel therapeutic strategies for the management of this malignancy.

RNA modifications in the progression of liver diseases: from fatty liver to cancer

Non-alcoholic fatty liver disease (NAFLD) has emerged as a prominent global health concern associated with high risk of metabolic syndrome, and has impacted a substantial segment of the population. The disease spectrum ranges from simple fatty liver to non-alcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma (HCC) and is increasingly becoming a prevalent indication for liver transplantation. The existing therapeutic options for NAFLD, NASH, and HCC are limited, underscoring the urgent need for innovative treatment strategies. Insights into gene expression, particularly RNA modifications such as N6 methyladenosine (m6A), hold promising avenues for interventions. These modifications play integral roles in RNA metabolism and cellular functions, encompassing the entire NAFLD-NASH-HCC progression. This review will encompass recent insights on diverse RNA modifications, including m6A, pseudouridine (ψ), N1-methyladenosine (m1A), and 5-methylcytidine (m5C) across various RNA species. It will uncover their significance in crucial aspects such as steatosis, inflammation, fibrosis, and tumorigenesis. Furthermore, prospective research directions and therapeutic implications will be explored, advancing our comprehensive understanding of the intricate interconnected nature of these pathological conditions.

LncRNA CCRR maintains Ca2+ homeostasis against myocardial infarction through the FTO-SERCA2a pathway

Cardiac conduction regulatory RNA (CCRR) has been documented as an antiarrhythmic lncRNA in our earlier investigation. This study aimed to evaluate the effects of CCRR on SERCA2a and the associated Ca2+ homeostasis in myocardial infarction (MI). Overexpression of CCRR via AAV9-mediated delivery not only partially reversed ischemia-induced contractile dysfunction but also alleviated abnormal Ca2+ homeostasis and reduced the heightened methylation level of SERCA2a following MI. These effects were also observed in CCRR over-expressing transgenic mice. A conserved sequence domain of CCRR mimicked the protective function observed with the full length. Furthermore, silencing CCRR in healthy mice led to intracellular Ca2+ overloading of cardiomyocytes. CCRR increased SERCA2a protein stability by upregulating FTO expression. The direct interaction between CCRR and FTO protein was characterized by RNA-binding protein immunoprecipitation (RIP) analysis and RNA pulldown experiments. Activation of NFATc3 was identified as an upstream mechanism responsible for CCRR downregulation in MI. This study demonstrates that CCRR is a protective lncRNA that acts by maintaining the function of FTO, thereby reducing the m6A RNA methylation level of SERCA2a, ultimately preserving calcium homeostasis for myocardial contractile function in MI. Therefore, CCRR may be considered a promising therapeutic strategy with a beneficial role in cardiac pathology.

Danggui Shaoyao San protects cyclophosphamide-induced premature ovarian failure by inhibiting apoptosis and oxidative stress through the regulation of the SIRT1/p53 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

It has been reported that apoptosis and oxidative stress are related to cyclophosphamide (CYC)-induced premature ovarian failure (POF). Therefore, anti-apoptotic and anti-oxidative stress treatments exhibit therapeutic efficacy in CYC-induced POF. Danggui Shaoyao San (DSS), which has been extensively used to treat gynecologic diseases, is found to inhibit apoptosis and reduce oxidative stress. However, the roles of DSS in regulating apoptosis and oxidative stress during CYC-induced POF, and its associated mechanisms are still unknown.

AIM OF THE STUDY

This work aimed to investigate the roles and mechanisms of DSS in inhibiting apoptosis and oxidative stress in CYC-induced POF.

MATERIALS AND METHODS

CYC (75 mg/kg) was intraperitoneally injected in mice to construct the POF mouse model for in vivo study. Thereafter, alterations of body weight, ovary morphology and estrous cycle were monitored to assess the ovarian protective properties of DSS. Serum LH and E2 levels were analyzed by enzyme-linked immunosorbent assay (ELISA). Hematoxylin-eosin (HE) staining was employed for examining ovarian pathological morphology and quantifying follicles in various stages. Meanwhile, TUNEL staining and apoptosis-related proteins were adopted for evaluating apoptosis. Oxidative stress was measured by the levels of ROS, MDA, and 4-HNE. Western blot (WB) assay was performed to detect proteins related to the SIRT1/p53 pathway. KGN cells were used for in vitro experiment. TBHP stimulation was carried out for establishing the oxidative stress-induced apoptosis cell model. Furthermore, MTT assay was employed for evaluating the protection of DSS from TBHP-induced oxidative stress. The anti-apoptotic ability of DSS was evaluated by hoechst/PI staining, JC-1 staining, and apoptosis-related proteins. Additionally, the anti-oxidative stress ability of DSS was measured by detecting the levels of ROS, MDA, and 4-HNE. Proteins related to SIRT1/p53 signaling pathway were also measured using WB and immunofluorescence (IF) staining. Besides, SIRT1 expression was suppressed by EX527 to further investigate the role of SIRT1 in the effects of DSS against apoptosis and oxidative stress.

RESULTS

In the in vivo experiment, DSS dose-dependently exerted its anti-apoptotic, anti-oxidative stress, and ovarian protective effects. In addition, apoptosis, apoptosis-related protein and oxidative stress levels were inhibited by DSS treatment. DSS treatment up-regulated SIRT1 and down-regulated p53 expression. From in vitro experiment, it was found that DSS treatment protected KGN cells from TBHP-induced oxidative stress injury. Besides, DSS administration suppressed the apoptosis ratio, apoptosis-related protein levels, mitochondrial membrane potential damage, and oxidative stress. SIRT1 suppression by EX527 abolished the anti-apoptotic, anti-oxidative stress, and ovarian protective effects, as discovered from in vivo and in vitro experiments.

CONCLUSIONS

DSS exerts the anti-apoptotic, anti-oxidative stress, and ovarian protective effects in POF mice, and suppresses the apoptosis and oxidative stress of KGN cells through activating SIRT1 and suppressing p53 pathway.

Emerging role of N6-methyladenosine RNA modification in regulation of SARS-CoV-2 infection and virus-host interactions

Since December 2019, the infection caused by Severe Acute Respiratory Syndrome Coronavirus Type 2 (SARS-CoV-2) has posed an enormous threat to human health security worldwide. Constant mutation of viral genome and varying therapeutic responses of patients infected with this virus prompted efforts to uncover more novel regulators in the pathogenesis. The involvement of N6-methyladenosine, a modified form of RNA, plays a crucial role in viral replication, viral pathogenicity, and intricate signaling pathways connected with immune responses. This review discusses research advances revealing the regulation of the life cycle of SARS-CoV-2 and antiviral responses of host cells by RNA m6A modification, highlights the biological functions of N6-methyladenosine components in SARS-CoV-2 infection and virus-host interactions, and outlines current challenges and future directions for exploring the potential clinical value of m6A modification in COVID-19.

RNA modification-mediated mRNA translation regulation in liver cancer: mechanisms and clinical perspectives

Malignant liver cancer is characterized by rapid tumour progression and a high mortality rate, whereas the molecular mechanisms underlying liver cancer initiation and progression are still poorly understood. The dynamic and reversible RNA modifications have crucial functions in gene expression regulation by modulating RNA processing and mRNA translation. Emerging evidence has revealed that alterations in RNA modifications facilitate the selective translation of oncogenic transcripts and promote the diverse tumorigenic processes of liver cancer. In this Review, we first highlight the current progress on the functions and mechanisms underlying RNA modifications in the regulation of mRNA translation and then summarize the exciting discoveries on aberrant RNA modification-mediated mRNA translation in the regulation of tumour initiation, metastasis, metabolism, tumour microenvironment, and drug and radiotherapy resistance in liver cancer. Finally, we discuss the diagnostic and therapeutic potentials of targeting RNA modifications and mRNA translation for the clinical management of liver cancer.

N6-methyladenosine (m6A) modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the deadliest cancers of human, the tumor-related death of which ranks third among the common malignances. N6-methyladenosine (m6A) methylation, the most abundant internal modification of RNA in mammals, participates in the metabolism of mRNA and interrelates with ncRNAs. In this paper, we overviewed the complex function of m6A regulators in HCC, including regulating the tumorigenesis, progression, prognosis, stemness, metabolic reprogramming, autophagy, ferroptosis, drug resistance and tumor immune microenvironment (TIME). Furthermore, we elucidated the interplay between m6A modification and non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). Finally, we summarized the potential of m6A regulators as diagnostic biomarkers. What's more, we reviewed the inhibitors targeting m6A enzymes as promising therapeutic targets of HCC. We aimed to help understand the function of m6A methylation in HCC systematically and comprehensively so that more effective strategies for HCC treatment will be developed.

METTL3 as a master regulator of translation in cancer: mechanisms and implications

Translational regulation is an important step in the control of gene expression. In cancer cells, the orchestration of both global control of protein synthesis and selective translation of specific mRNAs promote tumor cell survival, angiogenesis, transformation, invasion and metastasis. N6-methyladenosine (m6A), the most prevalent mRNA modification in higher eukaryotes, impacts protein translation. Over the past decade, the development of m6A mapping tools has facilitated comprehensive functional investigations, revealing the involvement of this chemical mark, together with its writer METTL3, in promoting the translation of both oncogenes and tumor suppressor transcripts, with the impact being context-dependent. This review aims to consolidate our current understanding of how m6A and METTL3 shape translation regulation in the realm of cancer biology. In addition, it delves into the role of cytoplasmic METTL3 in protein synthesis, operating independently of its catalytic activity. Ultimately, our goal is to provide critical insights into the interplay between m6A, METTL3 and translational regulation in cancer, offering a deeper comprehension of the mechanisms sustaining tumorigenesis.

Serum proteomic biomarker investigation of vascular depression using data-independent acquisition: a pilot study

Background

Vascular depression (VaD) is a depressive disorder closely associated with cerebrovascular disease and vascular risk factors. It remains underestimated owing to challenging diagnostics and limited information regarding the pathophysiological mechanisms of VaD. The purpose of this study was to analyze the proteomic signatures and identify the potential biomarkers with diagnostic significance in VaD.

Methods

Deep profiling of the serum proteome of 35 patients with VaD and 36 controls was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Functional enrichment analysis of the quantified proteins was based on Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and Reactome databases. Machine learning algorithms were used to screen candidate proteins and develop a protein-based model to effectively distinguish patients with VaD.

Results

There were 29 up-regulated and 31 down-regulated proteins in the VaD group compared to the controls (|log2FC| ≥ 0.26, p ≤ 0.05). Enrichment pathways analyses showed that neurobiological processes related to synaptic vesicle cycle and axon guidance may be dysregulated in VaD. Extrinsic component of synaptic vesicle membrane was the most enriched term in the cellular components (CC) terms. 19 candidate proteins were filtered for further modeling. A nomogram was developed with the combination of HECT domain E3 ubiquitin protein ligase 3 (HECTD3), Nidogen-2 (NID2), FTO alpha-ketoglutarate-dependent dioxygenase (FTO), Golgi membrane protein 1 (GOLM1), and N-acetylneuraminate lyase (NPL), which could be used to predict VaD risk with favorable efficacy.

Conclusion

This study offers a comprehensive and integrated view of serum proteomics and contributes to a valuable proteomics-based diagnostic model for VaD.

Contributing roles of mitochondrial dysfunction and hepatocyte apoptosis in liver diseases through oxidative stress, post-translational modifications, inflammation, and intestinal barrier dysfunction

This review provides an update on recent findings from basic, translational, and clinical studies on the molecular mechanisms of mitochondrial dysfunction and apoptosis of hepatocytes in multiple liver diseases, including but not limited to alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and drug-induced liver injury (DILI). While the ethanol-inducible cytochrome P450-2E1 (CYP2E1) is mainly responsible for oxidizing binge alcohol via the microsomal ethanol oxidizing system, it is also responsible for metabolizing many xenobiotics, including pollutants, chemicals, drugs, and specific diets abundant in n-6 fatty acids, into toxic metabolites in many organs, including the liver, causing pathological insults through organelles such as mitochondria and endoplasmic reticula. Oxidative imbalances (oxidative stress) in mitochondria promote the covalent modifications of lipids, proteins, and nucleic acids through enzymatic and non-enzymatic mechanisms. Excessive changes stimulate various post-translational modifications (PTMs) of mitochondrial proteins, transcription factors, and histones. Increased PTMs of mitochondrial proteins inactivate many enzymes involved in the reduction of oxidative species, fatty acid metabolism, and mitophagy pathways, leading to mitochondrial dysfunction, energy depletion, and apoptosis. Unique from other organelles, mitochondria control many signaling cascades involved in bioenergetics (fat metabolism), inflammation, and apoptosis/necrosis of hepatocytes. When mitochondrial homeostasis is shifted, these pathways become altered or shut down, likely contributing to the death of hepatocytes with activation of inflammation and hepatic stellate cells, causing liver fibrosis and cirrhosis. This review will encapsulate how mitochondrial dysfunction contributes to hepatocyte apoptosis in several types of liver diseases in order to provide recommendations for targeted therapeutics.

RNA m6A methylation regulators in liver cancer

Liver cancer is one of the most common cancers in the world and a primary cause of cancer-related death. In recent years, despite the great development of diagnostic methods and targeted therapies for liver cancer, the incidence and mortality of liver cancer are still on the rise. As a universal post-transcriptional modification, N6-methyladenosine (m6A) modification accomplishes a dynamic and reversible m6A modification process, which is executed by three types of regulators, methyltransferases (called writers), demethylases (called erasers) and m6A-binding proteins (called readers). Many studies have shown that m6A RNA methylation has an important impact on RNA metabolism, whereas its regulation exception is bound up with the occurrence of human malignant tumors. Aberrant methylation of m6A RNA and the expression of related regulatory factors may be of the essence in the pathogenesis and progression of liver cancer, yet the precise molecular mechanism remains unclear. In this paper, we review the current research situations of m6A methylation in liver cancer. Among the rest, we detail the mechanism by which methyltransferases, demethylases and m6A binding proteins regulate the occurrence and development of liver cancer by modifying mRNA. As well as the potential effect of m6A regulators in hepatocarcinogenesis and progression. New ideas and approaches will be given to the prevention and treatment of liver cancer through the following relevant research results.

The functions and mechanisms of post-translational modification in protein regulators of RNA methylation: Current status and future perspectives

RNA methylation, an epigenetic modification that does not alter gene sequence, may be important to diverse biological processes. Protein regulators of RNA methylation include "writers," "erasers," and "readers," which respectively deposit, remove, and recognize methylated RNA. RNA methylation, particularly N6-methyladenosine (m6A), 5-methylcytosine (m5C), N3-methylcytosine (m3C), N1-methyladenosine (m1A) and N7-methylguanosine (m7G), has been suggested as disease therapeutic targets. Despite advances in the structure and pharmacology of RNA methylation regulators that have improved drug discovery, regulating these proteins by various post-translational modifications (PTMs) has received little attention. PTM modifies protein structure and function, affecting all aspects of normal biology and pathogenesis, including immunology, cell differentiation, DNA damage repair, and tumors. It is becoming evident that RNA methylation regulators are also regulated by diverse PTMs. PTM of RNA methylation regulators induces their covalent linkage to new functional groups, hence modifying their activity and function. Mass spectrometry has identified many PTMs on protein regulators of RNA methylation. In this review, we describe the functions and PTM of protein regulators of RNA methylation and summarize the recent advances in the regulatory mode of human disease and its underlying mechanisms.

N6-methyladenosine (m6A) methylation in kidney diseases: Mechanisms and therapeutic potential

The N6-methyladenosine (m6A) modification is regulated by methylases, commonly referred to as "writers," and demethylases, known as "erasers," leading to a dynamic and reversible process. Changes in m6A levels have been implicated in a wide range of cellular processes, including nuclear RNA export, mRNA metabolism, protein translation, and RNA splicing, establishing a strong correlation with various diseases. Both physiologically and pathologically, m6A methylation plays a critical role in the initiation and progression of kidney disease. The methylation of m6A may also facilitate the early diagnosis and treatment of kidney diseases, according to accumulating research. This review aims to provide a comprehensive overview of the potential role and mechanism of m6A methylation in kidney diseases, as well as its potential application in the treatment of such diseases. There will be a thorough examination of m6A methylation mechanisms, paying particular attention to the interplay between m6A writers, m6A erasers, and m6A readers. Furthermore, this paper will elucidate the interplay between various kidney diseases and m6A methylation, summarize the expression patterns of m6A in pathological kidney tissues, and discuss the potential therapeutic benefits of targeting m6A in the context of kidney diseases.

Cellular gp96 upregulates AFP expression by blocking NR5A2 SUMOylation and ubiquitination in hepatocellular carcinoma

Alpha-fetoprotein (AFP) is the most widely used biomarker for the diagnosis of hepatocellular carcinoma (HCC). However, a substantial proportion of HCC patients have either normal or marginally increased AFP levels in serum, and the underlying mechanisms are not fully understood. In the present study, we provided in vitro and in vivo evidence that heat shock protein gp96 promoted AFP expression at the transcriptional level in HCC. NR5A2 was identified as a key transcription factor for the AFP gene, and its stability was enhanced by gp96. A further mechanistic study by co-immunoprecipitation, GST pull-down, and molecular docking showed gp96 and the SUMO E3 ligase RanBP2 competitively binding to NR5A2 at the sites spanning from aa 507 to aa 539. The binding of gp96 inhibited SUMOylation, ubiquitination, and subsequent degradation of NR5A2. In addition, clinical analysis of HCC patients indicated that gp96 expression in tumors was positively correlated with serum AFP levels. Therefore, our study uncovered a novel mechanism that gp96 regulates the stability of its client proteins by directly affecting their SUMOylation and ubiquitination. These findings will help in designing more accurate AFP-based HCC diagnosis and progression monitoring approaches.

Identification and verification of atrial fibrillation hub genes caused by primary mitral regurgitation

In the clinic, atrial fibrillation (AF) is a common arrhythmia. Despite constant innovation in treatments for AF, they remain limited by a lack of knowledge of the underlying mechanism responsible for AF. In this study, we examined the molecular mechanisms associated with primary mitral regurgitation (MR) in AF using several bioinformatics techniques. Limma was used to identify differentially expressed genes (DEGs) associated with AF using microarray data from the GSE115574 dataset. WGCNA was used to identify significant module genes. A functional enrichment analysis for overlapping genes between the DEGs and module genes was done and several AF hub genes were identified from a protein-protein interaction (PPI) network. Receiver operating characteristic (ROC) curves were generated to evaluate the validity of the hub genes. We examined 306 DEGs and 147 were upregulated and 159 were downregulated. WGCNA analysis revealed black and ivory modules that contained genes associated with AF. Functional enrichment analysis revealed various biological process terms related to AF. The AUCs for the 8 hub genes screened by the PPI network analysis were > 0.7, indicating satisfactory diagnostic accuracy. The 8 AF-related hub genes included SYT13, VSNL1, GNAO1, RGS4, RALYL, CPLX1, CHGB, and CPLX3. Our findings provide novel insight into the molecular mechanisms of AF and may lead to the development of new treatments.

Acetylation in pathogenesis: Revealing emerging mechanisms and therapeutic prospects

Protein acetylation modifications play a central and pivotal role in a myriad of biological processes, spanning cellular metabolism, proliferation, differentiation, apoptosis, and beyond, by effectively reshaping protein structure and function. The metabolic state of cells is intricately connected to epigenetic modifications, which in turn influence chromatin status and gene expression patterns. Notably, pathological alterations in protein acetylation modifications are frequently observed in diseases such as metabolic syndrome, cardiovascular disorders, and cancer. Such abnormalities can result in altered protein properties and loss of function, which are closely associated with developing and progressing related diseases. In recent years, the advancement of precision medicine has highlighted the potential value of protein acetylation in disease diagnosis, treatment, and prevention. This review includes provocative and thought-provoking papers outlining recent breakthroughs in acetylation modifications as they relate to cardiovascular disease, mitochondrial metabolic regulation, liver health, neurological health, obesity, diabetes, and cancer. Additionally, it covers the molecular mechanisms and research challenges in understanding the role of acetylation in disease regulation. By summarizing novel targets and prognostic markers for the treatment of related diseases, we aim to contribute to the field. Furthermore, we discuss current hot topics in acetylation research related to health regulation, including N4-acetylcytidine and liquid-liquid phase separation. The primary objective of this review is to provide insights into the functional diversity and underlying mechanisms by which acetylation regulates proteins in disease contexts.

Targeting SIRT1 synergistically improves the antitumor effect of JQ-1 in hepatocellular carcinoma

Bromodomain and extraterminal domain protein inhibitors have shown therapeutic promise in hepatocellular carcinoma. However, resistance to bromodomain and extraterminal domain protein inhibitors has emerged in preclinical trials, presenting an immense clinical challenge, and the mechanisms are unclear. In this study, we found that overexpression of SIRT1 induced by JQ-1, a bromodomain and extraterminal domain protein inhibitor, may confer resistance to JQ-1 in hepatocellular carcinoma. SIRT1 protein expression was higher in hepatocellular carcinoma tissues than in normal tissues, and this phenotype was correlated with a poor prognosis. Cotreatment with JQ-1 and the SIRT1 inhibitor EX527 synergistically suppressed proliferation and blocked cell cycle progression in hepatocellular carcinoma cells. Combined administration of JQ-1 and EX527 successfully reduced the tumor burden in vivo. In addition, JQ-1 mediated AMPK/p-AMPK axis activation to upregulate SIRT1 protein expression and enhanced autophagy to inhibit cell apoptosis. Activation of AMPK could alleviate the antitumor effect of the combination of JQ-1 and EX527 on hepatocellular carcinoma cells. Furthermore, inhibition of SIRT1 further enhanced the antitumor effect of JQ-1 by blocking protective autophagy in hepatocellular carcinoma. Our study proposes a novel and efficacious therapeutic strategy of a BET inhibitor combined with a SIRT1 inhibitor for hepatocellular carcinoma.

SUMOylation and DeSUMOylation: Prospective therapeutic targets in cancer

The SUMO family is a type of ubiquitin-like protein modification molecule. Its protein modification mechanism is similar to that of ubiquitination: both involve modifier-activating enzyme E1, conjugating enzyme E2 and substrate-specific ligase E3. However, polyubiquitination can lead to the degradation of substrate proteins, while poly-SUMOylation only leads to the degradation of substrate proteins through the proteasome pathway after being recognized by ubiquitin as a signal factor. There are currently five reported subtypes in the SUMO family, namely SUMO1-5. As a reversible dynamic modification, intracellular sentrin/SUMO-specific proteases (SENPs) mainly regulate the reverse reaction pathway of SUMOylation. The SUMOylation modification system affects the localization, activation and turnover of proteins in cells and participates in regulating most nuclear and extranuclear molecular reactions. Abnormal expression of proteins related to the SUMOylation pathway is commonly observed in tumors, indicating that this pathway is closely related to tumor occurrence, metastasis and invasion. This review mainly discusses the composition of members in the protein family related to SUMOylation pathways, mutual connections between SUMOylation and other post-translational modifications on proteins as well as therapeutic drugs developed based on these pathways.

m6A demethylase FTO stabilizes LINK-A to exert oncogenic roles via MCM3-mediated cell-cycle progression and HIF-1α activation

RNA N6-methyladenosine (m6A) modification is implicated in cancer progression, yet its role in regulating long noncoding RNAs during cancer progression remains unclear. Here, we report that the m6A demethylase fat mass and obesity-associated protein (FTO) stabilizes long intergenic noncoding RNA for kinase activation (LINK-A) to promote cell proliferation and chemoresistance in esophageal squamous cell carcinoma (ESCC). Mechanistically, LINK-A promotes the interaction between minichromosome maintenance complex component 3 (MCM3) and cyclin-dependent kinase 1 (CDK1), increasing MCM3 phosphorylation. This phosphorylation facilitates the loading of the MCM complex onto chromatin, which promotes cell-cycle progression and subsequent cell proliferation. Moreover, LINK-A disrupts the interaction between MCM3 and hypoxia-inducible factor 1α (HIF-1α), abrogating MCM3-mediated HIF-1α transcriptional repression and promoting glycolysis and chemoresistance. These results elucidate the mechanism by which FTO-stabilized LINK-A plays oncogenic roles and identify the FTO/LINK-A/MCM3/HIF-1α axis as a promising therapeutic target for ESCC.

Alternative splicing: a bridge connecting NAFLD and HCC

Non-alcoholic fatty liver disease (NAFLD) is becoming the most important risk factor for hepatocellular carcinoma (HCC). Understanding the progression of benign diseases to HCC is crucial for early prevention and reversal of malignant transformation. Alternative splicing (AS) of RNA plays a role in the pathogenicity, initiation, and transformation of liver disease. We summarize the changes or mutations in the activity of splicing factors in NAFLD and HCC, as well as the impact of AS mediated by epigenetic modifications such as DNA methylation, RNA methylation, histone modification, and protein phosphorylation on liver cell fate. We also summarize therapeutic methods and drugs that are helpful for treating NAFLD, HCC, and the early stages of NAFLD progression to HCC.

N6-methyladenosine RNA methylation in liver diseases: from mechanism to treatment

Epigenetic modification occurring in RNA has become the hotspot of the field. N6-methyladenosine (m6A) methylation is the most abundant RNA internal modification mainly occurring at the consensus motif DR (m6A) CH (D = A/G/U, R = A/G, H = A/C/U) in the 3'-UTR particularly the region near stop codons. The life cycle of m6A methylation includes "writers," "erasers," and "readers", which are responsible for the addition, removal, and recognition of m6A, respectively. m6A modification has been reported changing RNA secondary structure or modulating the stability, localization, transport, and translation of mRNAs to play crucial roles in various physiological and pathological conditions. Liver, as the largest metabolic and digestive organ, modulates vital physiological functions, and its dysfunction gives rise to the occurrence of various diseases. Despite the advanced intervening measures, mortality due to liver diseases is continuously high. Recent studies have explored the roles of m6A RNA methylation in the pathogenesis of liver diseases, providing new insights for studying the molecular mechanism of liver diseases. In the review, we extensively summarize the life cycle of m6A methylation, as well as its function and relevant mechanisms in liver fibrosis (LF), nonalcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), hepatitis virus infection, and hepatocellular carcinoma (HCC), and eventually we explore the potential of m6A as a treatment option for these liver diseases.

The roles and implications of RNA m6A modification in cancer

N6-Methyladenosine (m6A), the most prevalent internal modification in eukaryotic mRNA, has been extensively and increasingly studied over the past decade. Dysregulation of RNA m6A modification and its associated machinery, including writers, erasers and readers, is frequently observed in various cancer types, and the dysregulation profiles might serve as diagnostic, prognostic and/or predictive biomarkers. Dysregulated m6A modifiers have been shown to function as oncoproteins or tumour suppressors with essential roles in cancer initiation, progression, metastasis, metabolism, therapy resistance and immune evasion as well as in cancer stem cell self-renewal and the tumour microenvironment, highlighting the therapeutic potential of targeting the dysregulated m6A machinery for cancer treatment. In this Review, we discuss the mechanisms by which m6A modifiers determine the fate of target RNAs and thereby influence protein expression, molecular pathways and cell phenotypes. We also describe the state-of-the-art methodologies for mapping global m6A epitranscriptomes in cancer. We further summarize discoveries regarding the dysregulation of m6A modifiers and modifications in cancer, their pathological roles, and the underlying molecular mechanisms. Finally, we discuss m6A-related prognostic and predictive molecular biomarkers in cancer as well as the development of small-molecule inhibitors targeting oncogenic m6A modifiers and their activity in preclinical models.

The emerging roles of SUMOylation in the tumor microenvironment and therapeutic implications

Tumor initiation, progression, and response to therapies depend to a great extent on interactions between malignant cells and the tumor microenvironment (TME), which denotes the cancerous/non-cancerous cells, cytokines, chemokines, and various other factors around tumors. Cancer cells as well as stroma cells can not only obtain adaption to the TME but also sculpt their microenvironment through a series of signaling pathways. The post-translational modification (PTM) of eukaryotic cells by small ubiquitin-related modifier (SUMO) proteins is now recognized as a key flexible pathway. Proteins involved in tumorigenesis guiding several biological processes including chromatin organization, DNA repair, transcription, protein trafficking, and signal conduction rely on SUMOylation. The purpose of this review is to explore the role that SUMOylation plays in the TME formation and reprogramming, emphasize the importance of targeting SUMOylation to intervene in the TME and discuss the potential of SUMOylation inhibitors (SUMOi) in ameliorating tumor prognosis.

Epigenetic modification of m6A regulator proteins in cancer

Divergent N6-methyladenosine (m6A) modifications are dynamic and reversible posttranscriptional RNA modifications that are mediated by m6A regulators or m6A RNA methylation regulators, i.e., methyltransferases ("writers"), demethylases ("erasers"), and m6A-binding proteins ("readers"). Aberrant m6A modifications are associated with cancer occurrence, development, progression, and prognosis. Numerous studies have established that aberrant m6A regulators function as either tumor suppressors or oncogenes in multiple tumor types. However, the functions and mechanisms of m6A regulators in cancer remain largely elusive and should be explored. Emerging studies suggest that m6A regulators can be modulated by epigenetic modifications, namely, ubiquitination, SUMOylation, acetylation, methylation, phosphorylation, O-GlcNAcylation, ISGylation, and lactylation or via noncoding RNA action, in cancer. This review summarizes the current roles of m6A regulators in cancer. The roles and mechanisms for epigenetic modification of m6A regulators in cancer genesis are segregated. The review will improve the understanding of the epigenetic regulatory mechanisms of m6A regulators.

Role of sirtuins in hepatocellular carcinoma progression and multidrug resistance: Mechanistical and pharmacological perspectives

Hepatocellular carcinoma (HCC) is the third most common cause of death from cancer worldwide. Therapeutic strategies are still challenging due to the high relapse rate after surgery and multidrug resistance (MDR). It is essential to better understand the mechanisms for HCC progression and MDR for the development of new therapeutic strategies. Mammalian sirtuins (SIRTs), a family of seven members, are related to tumor progression, MDR and prognosis and were proposed as potential prognostic markers, as well as therapeutic targets for treating cancer. SIRT1 is the most studied member and is overexpressed in HCC, playing an oncogenic role and predicting poor prognosis. Several manuscripts describe the role of SIRTs2-7 in HCC; most of them report an oncogenic role for SIRT2 and -7 and a suppressive role for SIRT3 and -4. The scenario is more confusing for SIRT5 and -6, since information is contradictory and scarce. For SIRT1 many inhibitors are available and they seem to hold therapeutic promise in HCC. For the other members the development of specific modulators has just started. This review is aimed to describe the features of SIRTs1-7 in HCC, and the role they play in the onset and progression of the disease. Also, when possible, we will depict the information related to the SIRTs modulators that have been tested in HCC and their possible implication in MDR. With this, we hope to clarify the role of each member in HCC and to shed some light on the most successful strategies to overcome MDR.

The emerging importance role of m6A modification in liver disease

N6-methyladenosine (m6A) modification, as one of the most common types of inner RNA modification in eukaryotes, plays a multifunctional role in normal and abnormal biological processes. This type of modification is modulated by m6A writer, eraser and reader, which in turn impact various processes of RNA metabolism, such as RNA processing, translation, nuclear export, localization and decay. The current academic view holds that m6A modification exerts a crucial role in the post-transcriptional modulation of gene expression, and is involved in multiple cellular functions, developmental and disease processes. However, the potential molecular mechanism and specific role of m6A modification in the development of liver disease have not been fully elucidated. In our review, we summarized the latest research progress on m6A modification in liver disease, and explored how these novel findings reshape our knowledge of m6A modulation of RNA metabolism. In addition, we also illustrated the effect of m6A on liver development and regeneration to prompt further exploration of the mechanism and role of m6A modification in liver physiology and pathology, providing new insights and references for the search of potential therapeutic targets for liver disease.

SUMOylated IL-33 in the nucleus stabilizes the transcription factor IRF1 in hepatocellular carcinoma cells to promote immune escape

Interleukin-33 (IL-33) functions both as a secreted cytokine and as a nuclear factor, with pleiotropic roles in cancer and immunity. Here, we explored its role in hepatocellular carcinoma (HCC) and identified that a posttranslational modification altered its nuclear activity and promoted immune escape for HCC. IL-33 abundance was overall decreased but more frequently localized to the nucleus in patient HCC tissues than in normal liver tissues. In human and mouse HCC cells in culture and in vivo, IL-33 overexpression inhibited proliferation and repressed the abundance of programmed death ligand 1 (PD-L1) at the transcriptional level by promoting the ubiquitin-dependent degradation of interferon regulatory factor 1 (IRF1). However, this interaction was disrupted by SUMOylation of IL-33 at Lys⁵⁴ mediated by the E3 ligase RanBP2. IL-33 SUMOylation correlated with its nuclear localization in HCC cells and tumors. An increase in SUMOylated IL-33 in HCC cells in cocultures and in vivo stabilized IRF1 and increased PD-L1 abundance and chemokine IL-8 secretion, which prevented the activation of cytotoxic T cells and promoted the M2 polarization of macrophages, respectively. Mutating the SUMOylation site in IL-33 reversed these effects and suppressed tumor growth. These findings indicate that SUMOylation of nuclear IL-33 in HCC cells impairs antitumor immunity.

N6-methyladenosine in macrophage function: a novel target for metabolic diseases

N6-methyladenosine (m⁶A) is one of the most prevalent internal transcriptional modifications. Evidence has highlighted changes in m⁶A in metabolic disorders and various metabolic diseases. However, the precise mechanisms of these m⁶A changes in such conditions are not understood. Macrophages are crucial for the innate immune system and exert either beneficial or harmful roles in metabolic disease. Notably, m⁶A was found to be closely related to macrophage phenotype and dysfunction. In this review, we summarize m⁶A in macrophage function from the perspective of macrophage development, activation, and polarization, pyroptosis, and metabolic disorders. Furthermore, we discuss how m⁶A-mediated macrophage function affects metabolic diseases, including atherosclerosis and nonalcoholic fatty liver disease (NAFLD). Finally, we discuss challenges and prospects for m⁶A in macrophage and metabolic diseases with the aim of providing guidance for the treatment of metabolic diseases.

circRNA_0067717 promotes paclitaxel resistance in nasopharyngeal carcinoma by acting as a scaffold for TRIM41 and p53

PURPOSE

Circular RNAs (circRNAs) play important roles in tumour progression. This study aimed to explore the mechanism of hsa_circ_0067717 (termed circRNA_0067717) promoting paclitaxel resistance in nasopharyngeal carcinoma (NPC).

METHODS

We assayed CNE-1 and HNE-2 parental cell lines and the corresponding paclitaxel-resistant NPC cell lines using circRNA microarrays. RNA pull-down assay, RNA immunoprecipitation, and RNA fluorescence in situ hybridization were used to identify the molecular mechanisms.

RESULTS

Here, we confirm that circRNA_0067717 is significantly upregulated in NPC paclitaxel-resistant cells and is associated with paclitaxel resistance in NPC. Mechanistically, circRNA_0067717 functions as a scaffold for TRIM41 protein (a ubiquitin E3 ligase) and p53 protein. In nasopharyngeal carcinoma paclitaxel-resistant cells, the highly expressed circRNA_0067717 can bind to more TRIM41 and p53 protein, promoting TRIM41-induced p53 ubiquitination and degradation, resulting in a decrease in p53 protein level. Moreover, the 1-176 nt area of circRNA_0067717 and the 301-425 nt region of circRNA_0067717 are the binding sites for p53 and TRIM41, respectively. The resistance of NPC cells to paclitaxel can be reduced by blocking these binding regions of circRNA_0067717.

CONCLUSION

We demonstrate that circRNA_0067717 acts as a scaffold for TRIM41 and p53, enhancing paclitaxel chemoresistance in NPC by promoting TRIM41-induced p53 degradation via ubiquitination.

Targeting fat mass and obesity-associated protein mitigates human colorectal cancer growth in vitro and in a murine model

Introduction

Colorectal cancer (CRC) remains a significant cause of cancer related mortality. Fat mass and obesity-associated protein (FTO) is a m6A mRNA demethylase that plays an oncogenic role in various malignancies. In this study we evaluated the role of FTO in CRC tumorigenesis.

Methods

Cell proliferation assays were conducted in 6 CRC cell lines with the FTO inhibitor CS1 (50-3200 nM) (± 5-FU 5-80 mM) and after lentivirus mediated FTO knockdown. Cell cycle and apoptosis assays were conducted in HCT116 cells (24 h and 48 h, 290 nM CS1). Western blot and m6A dot plot assays were performed to assess CS1 inhibition of cell cycle proteins and FTO demethylase activity. Migration and invasion assays of shFTO cells and CS1 treated cells were performed. An in vivo heterotopic model of HCT116 cells treated with CS1 or with FTO knockdown cells was performed. RNA-seq was performed on shFTO cells to assess which molecular and metabolic pathways were impacted. RT-PCR was conducted on select genes down-regulated by FTO knockdown.

Results

We found that the FTO inhibitor, CS1 suppressed CRC cell proliferation in 6 colorectal cancer cell lines and in the 5-Fluorouracil resistant cell line (HCT116-5FUR). CS1 induced cell cycle arrest in the G2/M phase by down regulation of CDC25C and promoted apoptosis of HCT116 cells. CS1 suppressed in vivo tumor growth in the HCT116 heterotopic model (p< 0.05). Lentivirus knockdown of FTO in HCT116 cells (shFTO) mitigated in vivo tumor proliferation and in vitro demethylase activity, cell growth, migration and invasion compared to shScr controls (p< 0.01). RNA-seq of shFTO cells compared to shScr demonstrated down-regulation of pathways related to oxidative phosphorylation, MYC and Akt/ mTOR signaling pathways.

Discussion

Further work exploring the targeted pathways will elucidate precise downstream mechanisms that can potentially translate these findings to clinical trials.

SRSF10 stabilizes CDC25A by triggering exon 6 skipping to promote hepatocarcinogenesis

BACKGROUND

Alternative splicing (AS) events are extensively involved in the progression of diverse tumors, but how serine/arginine-rich splicing Factor 10 (SRSF10) behaves in hepatocellular carcinoma (HCC) has not been sufficiently studied. We aimed to determine SRSF10 associated AS mechanisms and their effects on HCC progression.

METHODS

The expression of SRSF10 in HCC tissues was examined, and the in vitro and in vivo functions of SRSF10 were investigated. The downstream AS targets were screened using RNA sequencing. The interaction between SRSF10 protein and exclusion of cell division cycle 25 A (CDC25A) mRNA was identified using RNA immunoprecipitation and crosslinking immunoprecipitation q-PCR. The effects of SRSF10 on CDC25A posttranslational modification, subcellular distribution, and protein stability were verified through coimmunoprecipitation, immunofluorescence, and western blotting.

RESULTS

SRSF10 was enriched in HCC tissues and facilitated HCC proliferation, cell cycle, and invasion. RNA sequencing showed that SRSF10 promotes exon 6 exclusion of CDC25A pre-mRNA splicing. As a crucial cell cycle mediator, the exon-skipped isoform CDC25A(△E6) was identified to be stabilized and retained in the nucleus due to the deletion of two ubiquitination (Lys150, Lys169) sites in exon 6. The stabilized isoform CDC25A(△E6) derived from AS had stronger cell cycle effects on HCC tumorigenesis, and playing a more significant role than the commonly expressed longer variant CDC25A(L). Interestingly, SRSF10 activated the carcinogenesis role of CDC25A through Ser178 dephosphorylation to cause nuclear retention. Moreover, CDC25A(△E6) was verified to be indispensable for SRSF10 to promote HCC development in vitro and in vivo.

CONCLUSIONS

We reveal a regulatory pattern whereby SRSF10 contributes to a large proportion of stabilized CDC25A(△E6) production, which is indispensable for SRSF10 to promote HCC development. Our findings uncover AS mechanisms such as CDC25A that might serve as potential therapeutic targets to treat HCC.

Systematic analysis of the expression profile and prognostic significance of m6A regulators and PD-L1 in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant tumor with poor prognosis. N6-methyladenosine (m6A) modification has dual biological functions in RNA modification and plays an important role in HCC.

METHODS

The GEO, TCGA, ONCOMINE, UALCAN, GEPIA, Kaplan-Meier plotter, cBioPortal for Cancer Genomics, STRING and TIMER2 databases were used for bioinformatic analyses. Quantitative polymerase chain reaction and western blotting were used to detect the expression of m6A regulators in HCC tissues.

RESULTS

The transcription of m6A regulators was upregulated in patients with HCC, and overexpression of YTHDF1/2, YTHDC1, RBM15 and METTL3 was significantly correlated with clinical stages of HCC. In addition, downregulation of ZC3H13 and METTL14 and upregulation of other m6A regulators were associated with a poor prognosis. A high mutation rate (89%) of m6A regulators was also observed in patients with HCC, and mutations in methylation regulators were associated with poor overall survival and disease-free survival. Finally, the expression of the YTHDF family was significantly associated with immune infiltration in the HCC microenvironment.

CONCLUSION

m6A regulators and programmed death-ligand 1 may play an important role in the tumorigenesis and immune invasion and escape of HCC and may be risk factors affecting the survival of patients with HCC.

The controversial role and therapeutic development of the m6A demethylase FTO in renal cell carcinoma

Fat mass and obesity-associated (FTO) protein, the first m6A demethylase identified in 2011, regulates multiple aspects of RNA biology including splicing, localization, stability, and translation. Accumulating data show that FTO is involved in numerous physiological processes and is implicated in multiple cancers including renal cell carcinoma (RCC). However, the exact role of FTO in RCC remains controversial. Some studies demonstrated that decreased FTO expression was associated with aggressive clinical features and shorter overall survival in clear cell RCC (ccRCC) patients, while others found that FTO inhibition selectively reduced the growth and survival of VHL-deficient ccRCC cells in vitro and in vivo. Here, we review the evidence supporting either a promoting or suppressive role of FTO in kidney cancers, the mechanisms of action of FTO, and recent progress in developing FTO inhibitors.

Senescent neutrophils-derived exosomal piRNA-17560 promotes chemoresistance and EMT of breast cancer via FTO-mediated m6A demethylation

Cellular senescence is characterized by a tumor-suppressive program as well as a pro-inflammatory secretome. Neutrophils constitute significant compositions of malignancies and play key roles in tumor development. However, the role of senescent neutrophils in cancer progression is presently unexplored. Here, we demonstrate that neutrophils display enhanced senescence in breast cancer patients receiving chemotherapy. The senescent neutrophils produce increased number of exosomes, which confer drug resistance to tumor cells in vitro and in vivo. Mechanistically, senescent neutrophils-derived exosomal piRNA-17560 enhances the expression of fat mass and obesity-associated protein (FTO) in breast cancer cells. The upregulation of FTO further strengthens ZEB1 transcripts stability and expression by decreasing N6-methyladenosine (m6A) RNA methylation, leading to chemoresistance and epithelial-mesenchymal transition (EMT) of tumor cells. Clinically, the level of exosomal piR-17560 correlates with poor chemotherapy response in patients with breast cancer. In addition, YTHDF2 is essential for the posttranscriptional regulation of ZEB1 by piRNA-17560/FTO signaling. Senescent neutrophils secret exosomal piR-17560 in a STAT3-dependent manner. Altogether, this study suggests that senescent neutrophils-derived exosomal piR-17560 confers chemoresistance to tumor cells and senescent neutrophils may serve as a potential therapeutic target in breast cancer.

UBE2O promotes lipid metabolic reprogramming and liver cancer progression by mediating HADHA ubiquitination

Cancer cells rely on heightened protein quality control mechanisms, including the ubiquitin-proteosome system that is predominantly driven by ubiquitination comprising E1, E2, and E3 trienzyme cascades. Although E3s have been extensively studied, the implication of E2s in tumorigenesis is poorly defined. Here we reveal a critical E2 in the pathogenesis of hepatocellular carcinoma (HCC). Among all of E2s, UBE2O shows the strongest association with HCC survival prognosis, and its expression is increased in HCC tumors. Accordingly, UBE2O deficiency inhibits HCC growth and metastasis both in vitro and in vivo, while its overexpression has opposite effects. Depending on both E2 and E3 enzymatic activities, UBE2O can interact with and mediate the ubiquitination and degradation of HADHA, a mitochondrial β-oxidation enzyme, thereby modulating lipid metabolic reprogramming. HADHA is reduced in HCC tumors and inversely correlated with UBE2O levels. Importantly, HADHA acts as a tumor suppressor and primarily mediates UBE2O's function on HCC. Moreover, liver-specific deletion of Ube2o in mice are resistant to DEN-induced hepatocarcinogenesis, along with HADHA upregulation and reduced hepatic lipid accumulation. These data reveal UBE2O as a novel oncogenic driver for metabolic reprogramming and HCC development, highlighting the potential of targeting UBE2O/HADHA axis for HCC therapy.

The role of RNA modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly mortal type of primary liver cancer. Abnormal epigenetic modifications are present in HCC, and RNA modification is dynamic and reversible and is a key post-transcriptional regulator. With the in-depth study of post-transcriptional modifications, RNA modifications are aberrantly expressed in human cancers. Moreover, the regulators of RNA modifications can be used as potential targets for cancer therapy. In RNA modifications, N6-methyladenosine (m6A), N7-methylguanosine (m7G), and 5-methylcytosine (m5C) and their regulators have important regulatory roles in HCC progression and represent potential novel biomarkers for the confirmation of diagnosis and treatment of HCC. This review focuses on RNA modifications in HCC and the roles and mechanisms of m6A, m7G, m5C, N1-methyladenosine (m1A), N3-methylcytosine (m3C), and pseudouridine (ψ) on its development and maintenance. The potential therapeutic strategies of RNA modifications are elaborated for HCC.

First case with RANBP2 biallelic mutation and severe acute necrotizing encephalopathy phenotype

Familial acute necrotizing encephalopathy (ANE) is a rapidly progressive encephalopathy that can occur after common viral infections at different stages of life. The clinical findings of 2 siblings diagnosed with ANE were shared and the whole-exome-sequencing study of the index case was performed. It was confirmed by the Sanger method. We found the RANBP2 gene p.I656V variant homozygous in the index case. We found the variant in the parents as heterozygous. We argue that biallelic mutations in the RANBP2 gene may result in ANE with early onset and severe prognosis by increasing penetrance.

Down-regulated m6A reader FTO destabilizes PHF1 that triggers enhanced stemness capacity and tumor progression in lung adenocarcinoma

Aberrant epigenetic drivers or suppressors contribute to LUAD progression and drug resistance, including KRAS, PTEN, Keap1. Human Plant Homeodomain (PHD) finger protein 1 (PHF1) coordinates with H3K36me3 to increase nucleosomal DNA accessibility. Previous studies revealed that PHF1 is markedly upregulated in various tumors and enhances cell proliferation, migration and tumorigenesis. However, its roles in LUAD are still unknown. We aimed to depict the biological roles of PHF1 and identify useful targets for clinical treatment of LUAD. Based on the bioinformatic analysis, we found that PHF1 was down-regulated in LUAD samples and low PHF1 expressions correlated with unfavorable clinical characteristics. Patients with low PHF1 had poorer survival outcomes relative to those with high PHF1. Targeting PHF1 potentiated cell growth, migration and in vivo proliferation. Mechanistically, FTO mediated the stabilization of PHF1 mRNA by demethylating m6A, which particularly prevented YTHDF2 from degrading PHF1 transcripts. Of note, FTO also expressed lowly in LUAD that predicts poor prognosis of patients. FTO inhibition promoted LUAD progression, and PHF1 overexpression could reverse the effect. Lastly, down-regulated FTO/PHF1 axis could mainly elevate FOXM1 expression to potentiate the self-renewal capacity. Targeting FOXM1 was effective to suppress PHF1^low/− LUAD growth. Collectively, our findings revealed that FTO positively regulates PHF1 expression and determined the tumor-suppressive role of FTO/PHF1 axis, thereby highlighting insights into its epigenetic remodeling mechanisms in LUAD progression and treatment.

SIRT1-mediated p53 deacetylation inhibits ferroptosis and alleviates heat stress-induced lung epithelial cells injury

OBJECTIVE

Acute lung injury (ALI) is a common complication of heat stroke (HS) and a direct cause of death. However, the mechanism underlying ALI following HS remains unclear.

METHOD

To investigate whether ferroptosis is involved in HS-ALI. We established a HS model of mice and mouse lung epithelial-2 cells (MLE-2). The severity of lung injury was measured by H&E staining, the wet-to-dry lung weight ratio, and Transmission electron microscopy. Potential markers of ferroptosis Fe²⁺, malondialdehyde (MDA), hydroxynonenal (4-HNE) and lipid peroxidation were detected. The percentages of cell death and viability induced by HS were assessed by LDH and CCK8 assays. SLC7A11, ACSL4, GPX4, SIRT1, p53, and p53 K382 acetylation levels were measured by Western blot.

RESULTS

The administration of ferroptosis inhibitor ferrostatin-1(Fer-1) could significantly ameliorate lung injury, inhibiting levels of MDA and 4-HNE, and ameliorating HS-induced increased ACSL4, decreased SLC7A11 and GPX4, suggesting ferroptosis was involved in HS-induced ALI in vivo and in vitro. Moreover, SIRT1 expression decreased, and p53 K382 acetylation levels increased in MLE-2 cells. Activation of SIRT1 could improve lung epithelial ferroptosis caused by HS in vivo ang in vitro. Besides, the activation of SIRT1 could significantly reduce the p53 K382 acetylation levels, suggesting that activation of SIRT1 could prevent ferroptosis via inhibiting p53 acetylation.

CONCLUSION

These findings substantiate the vital role of the SIRT1/p53 axis in mediating ferroptosis in HS-ALI, suggesting that targeting SIRT1 may represent a novel therapeutic strategy to ameliorate ALI during HS.

p53 m6A modulation sensitizes hepatocellular carcinoma to apatinib through apoptosis

Hepatocellular carcinoma (HCC) is insidious and prone to metastasis and recurrence. Currently, no effective treatment is available for HCC. Furthermore, HCC does not respond to various radio- and chemotherapies, and the molecular mechanism of treatment resistance is unclear. Here, we found that p53 n6-methyladenosine (m⁶A) played a decisive role in regulating HCC sensitivity to chemotherapy via the p53 activator RG7112 and the vascular endothelial growth factor receptor inhibitor apatinib. Our results reveal that p53 activation plays a crucial role in chemotherapy-induced apoptosis and reducing cell viability. Moreover, decreasing m⁶A methyltransferase (e.g., methyltransferase-like 3, METTL3) expression through chemotherapeutic drug combinations reduced p53 mRNA m⁶A modification. p53 mRNA m⁶A modification blockage induced by S-adenosyl homocysteine or siRNA-mediated METTL3 inhibition enhanced HCC sensitivity to chemotherapy. Importantly, we observed that downregulation of METTL3 and upregulation of p53 expression by oral administration of chemotherapy drugs triggered apoptosis and xenograft tumor growth inhibition in nude mice. Based on these findings, we hypothesize that a METTL3-m⁶A-p53 axis could be a potential target in HCC therapy.

N6-Methyladenosine Demethylase FTO (Fat Mass and Obesity-Associated Protein) as a Novel Mediator of Statin Effects in Human Endothelial Cells

BACKGROUND

N6-methyladenosine (m6A) plays a critical role in various biological processes. However, no study has addressed the role of m6A modification in the statin-induced protection of endothelial cells (ECs).

METHODS

Quantitative real-time polymerase chain reaction and Western blotting analyses were used to study the expression of m6A regulatory genes in atorvastatin-treated ECs. Gain- and loss-of-function assays, methylated RNA immunoprecipitation analysis, and dual-luciferase reporter assays were performed to clarify the function of FTO (fat mass and obesity-associated protein) in ECs.

RESULTS

Atorvastatin decreased FTO protein expression in ECs. The knockdown of FTO enhanced the mRNA and protein expression of KLF2 (Kruppel-like factor 2) and eNOS (endothelial NO synthase) but attenuated TNFα (tumor necrosis factor alpha)-induced VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) expression, as well as the adhesion of monocytes to ECs. Conversely, FTO overexpression significantly upregulated the mRNA and protein levels of VCAM-1 and ICAM-1, downregulated those of KLF2 and eNOS, and strongly attenuated the atorvastatin-mediated induction of KLF2 and eNOS expression. Subsequent investigations demonstrated that KLF2 and eNOS are functionally critical targets of FTO. Mechanistically, FTO interacted with KLF2 and eNOS transcripts and regulated their expression in an m6A-dependent manner. After FTO silencing, KLF2 and eNOS transcripts with higher levels of m6A modification in their 3' untranslated regions were captured by YTHDF3 (YT521-B homology m6A RNA-binding protein 3), resulting in mRNA stabilization and the induction of KLF2 and eNOS protein expression.

CONCLUSIONS

FTO might serve as a novel molecular target to modulate endothelial function in vascular diseases.

Identification and Validation of N6-Methyladenosine-Related Biomarkers for Bladder Cancer: Implications for Immunotherapy

N6-methyladenosine (m⁶A) has emerged as one of the most important modifications of RNA. Based on the expression of 23 different modes of m⁶A regulatory factors, we identified three different m⁶A modification patterns in bladder cancer. The effects of the three different modes of m⁶A modification on clinicopathological characteristics, immune cell infiltration levels and expression levels of immune checkpoint genes were comprehensively analyzed. In addition, the effects of different modes of m⁶A modification on the therapeutic efficacy of anti-PD-L1 immunotherapy (atezolizumab) are also discussed. Our results confirm that m⁶A methylation plays an important role in immune cell recruitment in the tumor microenvironment of bladder cancer, which influences the efficacy of anti-PD-L1 therapy for bladder cancer. We further confirmed the important role of FTO protein in the biological function of bladder cancer cells by performing in vitro experiments. FTO functions as an oncogene in bladder cancer cells, and upon FTO knockdown, the level of m⁶A enzyme activity in bladder cancer cells was significantly increased, apoptosis was increased, and cell proliferation and cell invasion were reduced. In addition, our study also confirmed that K216H and K216E are probably important targets for regulating FTO. We provide new insights into the regulatory pathways of the immune microenvironment and the methylation function of m⁶A in bladder cancer, which will help in designing novel diagnostic methods, prognostic tools, and therapeutic targets.

Circular RNA_0057209 Acts as ceRNA to Inhibit Thyroid Cancer Progression by Promoting the STK4-Mediated Hippo Pathway via Sponging MicroRNA-183

Thyroid cancer is the most common malignancy of the endocrine system, and its outcome remains unsatisfactory. In recent years, circular RNAs (circRNAs) have emerged as crucial regulators in cancers. In the current study, we aimed to investigate whether and how circRNA_0057209 functioned in thyroid cancer. Initial results revealed that circRNA_0057209 and STK4 were both reduced, while miR-183 was up-regulated in thyroid cancer tissues and cells. Experiments including RNA pull-down and RIP assays further identified that upregulation of circRNA_0057209 augmented the expression of STK4, a target gene of miR-183, by competitively-binding to miR-183. Furthermore, functional experiments provided evidence that overexpression of circRNA_0057209 not only inhibited the proliferative, migratory, and invasive properties of thyroid cancer cells while facilitating their apoptosis but also delayed tumor growth. Conversely, upregulation of miR-183 or silencing of STK4 reversed the changes induced by circRNA_0057209. Meanwhile, mechanistic experimentation demonstrated that circRNA_0057209 promoted STK4 expression by sponging miR-183, while STK4 enhanced YAP phosphorylation to mediate the Hippo pathway, thereby suppressing tumor progression. Altogether, our findings indicated that circRNA_0057209 may serve as a competing endogenous RNA of miR-183 to increase STK4 expression, thus inhibiting the development of thyroid cancer.

SPI1-induced downregulation of FTO promotes GBM progression by regulating pri-miR-10a processing in an m6A-dependent manner

As one of the most common post-transcriptional modifications of mRNAs and noncoding RNAs, N⁶-methyladenosine (m⁶A) modification regulates almost every aspect of RNA metabolism. Evidence indicates that dysregulation of m⁶A modification and associated proteins contributes to glioblastoma (GBM) progression. However, the function of fat mass and obesity-associated protein (FTO), an m⁶A demethylase, has not been systematically and comprehensively explored in GBM. Here, we found that decreased FTO expression in clinical specimens correlated with higher glioma grades and poorer clinical outcomes. Functionally, FTO inhibited growth and invasion in GBM cells in vitro and in vivo. Mechanistically, FTO regulated the m⁶A modification of primary microRNA-10a (pri-miR-10a), which could be recognized by reader HNRNPA2B1, recruiting the microRNA microprocessor complex protein DGCR8 and mediating pri-miR-10a processing. Furthermore, the transcriptional activity of FTO was inhibited by the transcription factor SPI1, which could be specifically disrupted by the SPI1 inhibitor DB2313. Treatment with this inhibitor restored endogenous FTO expression and decreased GBM tumor burden, suggesting that FTO may serve as a novel prognostic indicator and therapeutic molecular target of GBM.

m6A methylation is required for dihydroartemisinin to alleviate liver fibrosis by inducing ferroptosis in hepatic stellate cells

Activation of hepatic stellate cells (HSCs) is a central event in the development of liver fibrosis, and the elimination of activated HSCs is considered to be an effective anti-fibrotic strategy. Here, we report that dihydroartemisinin (DHA) prevented the activation of HSCs via ferroptosis pathway. Importantly, DHA treatment increased the level of autophagy in HSCs. The inhibition of autophagy by 3-MA dramatically abolished the DHA-induced ferroptosis in HSCs. Mechanistically, the up-regulated m⁶A modification is essential for the activation of autophagy by DHA through the reduction of fat mass and obesity-associated gene (FTO). Down-regulation of m⁶A modification by FTO overexpression could impair autophagy and the classical ferroptotic events. Interestingly, the m⁶A modification of BECN1 mRNA was evidently up-regulated compared with other autophagy-related genes. More importantly, YTHDF1 was identified as a key m⁶A reader protein for BECN1 mRNA stability, and knockdown of YTHDF1 could prevent DHA-induced HSC ferroptosis. Noteworthy, YTH domain was essential for YTHDF1 to prolong the half-life of BECN1 mRNA in DHA-induced HSC ferroptosis. In mice, DHA treatment alleviated liver fibrosis by triggering HSC ferroptosis. HSC-specific inhibition of m⁶A modification and autophagy could impair DHA-induced HSC ferroptosis in murine liver fibrosis. Overall, these results provided novel implications to reveal the molecular mechanism of DHA-induced ferroptosis, by which pointed to m⁶A modification-dependent ferroptosis as a potential target for the treatment of liver fibrosis.

Mutant NPM1-Regulated FTO-Mediated m6A Demethylation Promotes Leukemic Cell Survival via PDGFRB/ERK Signaling Axis

Acute myeloid leukemia (AML) with nucleophosmin 1 (NPM1) mutations exhibits distinct biological and clinical features, accounting for approximately one-third of AML. Recently, the N⁶-methyladenosine (m⁶A) RNA modification has emerged as a new epigenetic modification to contribute to tumorigenesis and development. However, there is limited knowledge on the role of m⁶A modifications in NPM1-mutated AML. In this study, the decreased m⁶A level was first detected and high expression of fat mass and obesity-associated protein (FTO) was responsible for the m⁶A suppression in NPM1-mutated AML. FTO upregulation was partially induced by NPM1 mutation type A (NPM1-mA) through impeding the proteasome pathway. Importantly, FTO promoted leukemic cell survival by facilitating cell cycle and inhibiting cell apoptosis. Mechanistic investigations demonstrated that FTO depended on its m⁶A RNA demethylase activity to activate PDGFRB/ERK signaling axis. Our findings indicate that FTO-mediated m⁶A demethylation plays an oncogenic role in NPM1-mutated AML and provide a new layer of epigenetic insight for future treatments of this distinctly leukemic entity.

m6A modification: recent advances, anticancer targeted drug discovery and beyond

Abnormal N6-methyladenosine (m6A) modification is closely associated with the occurrence, development, progression and prognosis of cancer, and aberrant m6A regulators have been identified as novel anticancer drug targets. Both traditional medicine-related approaches and modern drug discovery platforms have been used in an attempt to develop m6A-targeted drugs. Here, we provide an update of the latest findings on m6A modification and the critical roles of m6A modification in cancer progression, and we summarize rational sources for the discovery of m6A-targeted anticancer agents from traditional medicines and computer-based chemosynthetic compounds. This review highlights the potential agents targeting m6A modification for cancer treatment and proposes the advantage of artificial intelligence (AI) in the discovery of m6A-targeting anticancer drugs.

Graphical abstract

Three stages of m6A-targeting anticancer drug discovery: traditional medicine-based natural products, modern chemical modification or synthesis, and artificial intelligence (AI)-assisted approaches for the future.