FTO Inhibition Enhances the Antitumor Effect of Temozolomide by Targeting MYC-miR-155/23a Cluster-MXI1 Feedback Circuit in Glioma

Retracted article: Knockdown of long non-coding RNA AGAP2-AS1 suppresses the proliferation and metastasis of glioma by targeting microRNA-497-5p

Yi Sun, Yulong Shen and Xing Li. Knockdown of long non-coding RNA AGAP2-AS1 suppresses the proliferation and metastasis of glioma by targeting microRNA-497-5p. Bioengineered. 2021 Oct. doi: 10.1080/21655979.2021.1995573.Since publication, significant concerns have been raised about the compliance with ethical policies for human research and the integrity of the data reported in the article.When approached for an explanation, the authors provided some original data but were not able to provide all the necessary supporting information. As verifying the validity of published work is core to the scholarly record's integrity, we are retracting the article. All authors listed in this publication have been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted.'

Repurposing auranofin and meclofenamic acid as energy-metabolism inhibitors and anti-cancer drugs

OBJECTIVE

Cytotoxicity of the antirheumatic drug auranofin (Aur) and the non-steroidal anti-inflammatory drug meclofenamic acid (MA) on several cancer cell lines and isolated mitochondria was examined to assess whether these drugs behave as oxidative phosphorylation inhibitors.

METHODS

The effect of Aur or MA for 24 h was assayed on metastatic cancer and non-cancer cell proliferation, energy metabolism, mitophagy and metastasis; as well as on oxygen consumption rates of cancer and non-cancer mitochondria.

RESULTS

Aur doses in the low micromolar range were required to decrease proliferation of metastatic HeLa and MDA-MB-231 cells, whereas one or two orders of magnitude higher levels were required to affect proliferation of non-cancer cells. MA doses required to affect cancer cell growth were one order of magnitude higher than those of Aur. At the same doses, Aur impaired oxidative phosphorylation in isolated mitochondria and intact cells through mitophagy induction, as well as glycolysis. Consequently, cell migration and invasiveness were severely affected. The combination of Aur with very low cisplatin concentrations promoted that the effects on cellular functions were potentiated.

CONCLUSION

Aur surges as a highly promising anticancer drug, suggesting that efforts to establish this drug in the clinical treatment protocols are warranted and worthy to undertake.

FTO diversely influences sensitivity of neuroblastoma cells to various chemotherapeutic drugs

Chemotherapy resistance is a significant factor in treatment failure in patients with neuroblastoma (NB), and it directly affects patient prognosis. Therefore, identifying novel therapeutic targets to enhance chemosensitivity is essential to improve the cure rate and prognosis of patients with NB. In this study, we investigated the role of FTO in chemosensitivity of NB cells to various chemotherapeutic drugs. Our results showed that high FTO expression was positively correlated with increased survival probability and favorable prognostic factors in patients with NB. FTO overexpression inhibited cell proliferation, whereas FTO knockdown promoted cell proliferation in NB cells. FTO expression alteration had contrasting effects on NB cells' sensitivity to etoposide but had no significant impact on sensitivity to cisplatin. Downregulation of FTO reduced the sensitivity of NB cells to paclitaxel, whereas upregulation of FTO enhanced its sensitivity. Additionally, the sensitivities between patients with lower and higher FTO expression to various chemotherapeutic drugs or small-molecule inhibitors were different. Thus, FTO affects the sensitivities of NB cells differently depending on the different chemotherapeutic drugs and small-molecule inhibitors. This finding may guide physicians and patients choose the appropriate chemotherapeutic drugs or small-molecule inhibitors for treatment.

Unveiling the role of RNA methylation in glioma: Mechanisms, prognostic biomarkers, and therapeutic targets

Gliomas, the most prevalent malignant brain tumors in the central nervous system, are marked by rapid growth, high recurrence rates, and poor prognosis. Glioblastoma (GBM) stands out as the most aggressive subtype, characterized by significant heterogeneity. The etiology of gliomas remains elusive. RNA modifications, particularly reversible methylation, play a crucial role in regulating transcription and translation throughout the RNA lifecycle. Increasing evidence highlights the prevalence of RNA methylation in primary central nervous system malignancies, underscoring its pivotal role in glioma pathogenesis. This review focuses on recent findings regarding changes in RNA methylation expression and their effects on glioma development and progression, including N6-methyladenosine (m6A), 5-methylcytosine (m5C), N1-methyladenosine (m1A), and N7-methylguanosine (m7G). Given the extensive roles of RNA methylation in gliomas, the potential of RNA methylation-related regulators as prognostic markers and therapeutic targets was also explored, aiming to enhance clinical management and improve patient outcomes.

Fenamates: Forgotten treasure for cancer treatment and prevention: Mechanisms of action, structural modification, and bright future

Fenamates as classical nonsteroidal anti-inflammatory agents are widely used for relieving pain. Preclinical studies and epidemiological data highlight their chemo-preventive and chemotherapeutic potential for cancer. However, comprehensive reviews of fenamates in cancer are limited. To accelerate the repurposing of fenamates, this review summarizes the results of fenamates alone or in combination with existing chemotherapeutic agents. This paper also explores targets of fenamates in cancer therapy, including COX, AKR family, AR, gap junction, FTO, TEAD, DHODH, TAS2R14, ion channels, and DNA. Besides, this paper discusses other mechanisms, such as regulating Wnt/β-catenin, TGF-β, p38 MAPK, and NF-κB pathway, and the regulation of the expressions of Sp, EGR-1, NAG-1, ATF-3, ErbB2, AR, as well as the modulation of the tumor immune microenvironment. Furthermore, this paper outlined the structural modifications of fenamates, highlighting their potential as promising leads for anticancer drugs.

Medicinal chemistry aspects of fat mass and obesity associated protein: structure, function and inhibitors

Adiposity and obesity-related proteins (FTO), the earliest identified mRNA N6-methyladenosine (m6A) demethylases, are known to play crucial roles in several biological processes. Therefore, FTO is a promising target for anticancer treatment. Understanding the biological functions and regulatory mechanisms of FTO targets can serve as guidelines for drug development. Despite significant efforts to develop FTO inhibitors, no specific small-molecule inhibitors have entered clinical trials so far. In this manuscript, we review the relationship between FTO and various cancers, the small-molecule inhibitors developed against FTO targets from the perspective of medicinal chemistry and other fields, and describe their structural optimization process and structure-activity relationship, providing clues for their future development direction.

FTO promotes gefitinib-resistance by enhancing PELI3 expression and autophagy in non-small cell lung cancer

The established recognition of N6-methyladenosine (m6A) modification as an indispensable regulatory agent in human cancer is widely accepted. However, the understanding of m6A's role and the mechanisms underlying its contribution to gefitinib resistance is notably limited. Herein, using RT-qPCR, Western blot, Cell proliferation and apoptosis, as well as RNA m6A modification assays, we substantiated that heightened FTO (Fat Mass and Obesity-associated protein) expression substantially underpins the emergence of gefitinib resistance in NSCLC cells. This FTO-driven gefitinib resistance is hinged upon the co-occurrence of PELI3 (Pellino E3 Ubiquitin Protein Ligase Family Member 3) expression and concurrent autophagy activation. Manipulation of PELI3 expression and autophagy activation, including its attenuation, was efficacious in both inducing and overcoming gefitinib resistance within NSCLC cells, as validated in vitro and in vivo. In summary, this study has successfully elucidated the intricate interplay involving FTO-mediated m6A modification, its consequential downstream effect on PELI3, and the concurrent involvement of autophagy in fostering the emergence of gefitinib resistance within the therapeutic context of NSCLC.

Role of N6-methyladenosine in tumor neovascularization

Tumor neovascularization is essential for the growth, invasion, and metastasis of tumors. Recent studies have highlighted the significant role of N6-methyladenosine (m6A) modification in regulating these processes. This review explores the mechanisms by which m6A influences tumor neovascularization, focusing on its impact on angiogenesis and vasculogenic mimicry (VM). We discuss the roles of m6A writers, erasers, and readers in modulating the stability and translation of angiogenic factors like vascular endothelial growth factor (VEGF), and their involvement in key signaling pathways such as PI3K/AKT, MAPK, and Hippo. Additionally, we outline the role of m6A in vascular-immune crosstalk. Finally, we discuss the current development of m6A inhibitors and their potential applications, along with the contribution of m6A to anti-angiogenic therapy resistance. Highlighting the therapeutic potential of targeting m6A regulators, this review provides novel insights into anti-angiogenic strategies and underscores the need for further research to fully exploit m6A modulation in cancer treatment. By understanding the intricate role of m6A in tumor neovascularization, we can develop more effective therapeutic approaches to inhibit tumor growth and overcome treatment resistance. Targeting m6A offers a novel approach to interfere with the tumor's ability to manipulate its microenvironment, enhancing the efficacy of existing treatments and providing new avenues for combating cancer progression.

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.

Role of Non-coding RNAs in the Response of Glioblastoma to Temozolomide

Chemotherapy and radiotherapy are widely used in clinical practice across the globe as cancer treatments. Intrinsic or acquired chemoresistance poses a significant problem for medical practitioners and researchers, causing tumor recurrence and metastasis. The most dangerous kind of malignant brain tumor is called glioblastoma multiforme (GBM) that often recurs following surgery. The most often used medication for treating GBM is temozolomide chemotherapy; however, most patients eventually become resistant. Researchers are studying preclinical models that accurately reflect human disease and can be used to speed up drug development to overcome chemoresistance in GBM. Non-coding RNAs (ncRNAs) have been shown to be substantial in regulating tumor development and facilitating treatment resistance in several cancers, such as GBM. In this work, we mentioned the mechanisms of how different ncRNAs (microRNAs, long non-coding RNAs, circular RNAs) can regulate temozolomide chemosensitivity in GBM. We also address the role of these ncRNAs encapsulated inside secreted exosomes.

A Methylation-Gated DNAzyme Circuit for Spatially Controlled Imaging of MicroRNA in Cells and Animals

Epigenetic modification plays an indispensable role in regulating routine molecular signaling pathways, yet it is rarely used to modulate molecular self-assembly networks. Herein, we constructed a bioorthogonal demethylase-stimulated DNA circuitry (DSC) system for high-fidelity imaging of microRNA (miRNA) in live cells and mice by eliminating undesired off-site signal leakage. The simple and robust DSC system is composed of a primary cell-specific circuitry regulation (CR) module and an ultimate signal-transducing amplifier (SA) module. After the modularly designed DSC system was delivered into target live cells, the DNAzyme of the CR module was site-specifically activated by endogenous demethylase to produce fuel strands for the subsequent miRNA-targeting SA module. Through the on-site and multiply guaranteed molecular recognitions, the lucid yet efficient DSC system realized the reliably amplified in vivo miRNA sensing and enabled the in-depth exploration of the demethylase-involved signal pathway with miRNA in live cells. Our bioorthogonally on-site-activated DSC system represents a universal and versatile biomolecular sensing platform via various demethylase regulations and shows more prospects for more different personalized theragnostics.

Demethylases in tumors and the tumor microenvironment: Key modifiers of N6-methyladenosine methylation

RNA methylation modifications are widespread in eukaryotes and prokaryotes, with N6-methyladenosine (m6A) the most common among them. Demethylases, including Fat mass and obesity associated gene (FTO) and AlkB homolog 5 (ALKBH5), are important in maintaining the balance between RNA methylation and demethylation. Recent studies have clearly shown that demethylases affect the biological functions of tumors by regulating their m6A levels. However, their effects are complicated, and even opposite results have appeared in different articles. Here, we summarize the complex regulatory networks of demethylases, including the most important and common pathways, to clarify the role of demethylases in tumors. In addition, we describe the relationships between demethylases and the tumor microenvironment, and introduce their regulatory mechanisms. Finally, we discuss evaluation of demethylases for tumor diagnosis and prognosis, as well as the clinical application of demethylase inhibitors, providing a strong basis for their large-scale clinical application in the future.

Targeting non-coding RNAs and N6-methyladenosine modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common form of primary liver cancers, accounts for a significant portion of cancer-related death globally. However, the molecular mechanisms driving the onset and progression of HCC are still not fully understood. Emerging evidence has indicated that non-protein-coding regions of genomes could give rise to transcripts, termed non-coding RNA (ncRNA), forming novel functional driving force for aberrant cellular activity. Over the past decades, overwhelming evidence has denoted involvement of a complex array of molecular function of ncRNAs at different stages of HCC tumorigenesis and progression. In this context, several pre-clinical studies have highlighted the potentials of ncRNAs as novel therapeutic modalities in the management of human HCC. Moreover, N6-methyladenosine (m6A) modification, the most prevalent form of internal mRNA modifications in mammalian cells, is essential for the governance of biological processes within cells. Dysregulation of m6A in ncRNAs has been implicated in human carcinogenesis, including HCC. In this review, we will discuss dysregulation of several hallmark ncRNAs (miRNAs, lncRNAs, and circRNAs) in HCC and address the latest advances for their involvement in the onset and progression of HCC. We also focus on dysregulation of m6A modification and various m6A regulators in the etiology of HCC. In the end, we discussed the contemporary preclinical and clinical application of ncRNA-based and m6A-targeted therapies in HCC.

Emerging Roles and Mechanisms of RNA Modifications in Neurodegenerative Diseases and Glioma

Despite a long history of research, neurodegenerative diseases and malignant brain tumor gliomas are both considered incurable, facing challenges in the development of treatments. Recent evidence suggests that RNA modifications, previously considered as static components of intracellular RNAs, are in fact dynamically regulated across various RNA species in cells and play a critical role in major biological processes in the nervous system. Innovations in next-generation sequencing have enabled the accurate detection of modifications on bases and sugars within various RNA molecules. These RNA modifications influence the stability and transportation of RNA, and crucially affect its translation. This review delves into existing knowledge on RNA modifications to offer a comprehensive inventory of these modifications across different RNA species. The detailed regulatory functions and roles of RNA modifications within the nervous system are discussed with a focus on neurodegenerative diseases and gliomas. This article presents a comprehensive overview of the fundamental mechanisms and emerging roles of RNA modifications in these diseases, which can facilitate the creation of innovative diagnostics and therapeutics for these conditions.

The impact of tRNA modifications on translation in cancer: identifying novel therapeutic avenues

Recent advancements have illuminated the critical role of RNA modifications in post-transcriptional regulation, shaping the landscape of gene expression. This review explores how tRNA modifications emerge as critical players, fine-tuning functionalities that not only maintain the fidelity of protein synthesis but also dictate gene expression and translation profiles. Highlighting their dysregulation as a common denominator in various cancers, we systematically investigate the intersection of both cytosolic and mitochondrial tRNA modifications with cancer biology. These modifications impact key processes such as cell proliferation, tumorigenesis, migration, metastasis, bioenergetics and the modulation of the tumor immune microenvironment. The recurrence of altered tRNA modification patterns across different cancer types underscores their significance in cancer development, proposing them as potential biomarkers and as actionable targets to disrupt tumorigenic processes, offering new avenues for precision medicine in the battle against cancer.

M6A RNA methylation in biliary tract cancer: the function roles and potential therapeutic implications

Biliary tract cancers (BTCs) are relatively rare malignancies with a poor prognosis. For advanced BTCs, the efficacy of current chemotherapeutic approaches is limited. Consequently, there is an urgent need to deepen our understanding of the molecular mechanisms underlying BTC tumorigenesis and development for the exploration of effective targeted therapies. N6-methyladenosine (m6A), the most abundant RNA modifications in eukaryotes, is found usually dysregulated and involved in tumorigenesis, progression, and drug resistance in tumors. Numerous studies have confirmed that aberrant m6A regulators function as either oncogenes or tumor suppressors in BTCs by the reversible regulation of RNA metabolism, including splicing, export, degradation and translation. In this review, we summarized the current roles of the m6A regulators and their functional impacts on RNA fate in BTCs. The improved understanding of m6A modification in BTCs also provides a reasonable outlook for the exploration of new diagnostic strategies and efficient therapeutic targets.

Research Advances in the Roles of N6-Methyladenosine Modification in Ovarian Cancer

Ovarian cancer (OC) is the most lethal gynecological tumor, characterized by its insidious and frequently recurring metastatic progression. Owing to limited early screening methods, over 70% of OC cases are diagnosed at advanced stages, typically stage III or IV. Recently, N6-methyladenosine (m6A) modification has emerged as a hotspot of epigenetic research, representing a significant endogenous RNA modification in higher eukaryotes. Numerous studies have reported that m6A-related regulatory factors play pivotal roles in tumor development through diverse mechanisms. Moreover, recent studies have indicated the aberrant expression of multiple regulatory factors in OC. Therefore, this paper comprehensively reviews research advancements concerning m6A in OC, aiming to elucidate the regulatory mechanism of m6A-associated regulators on pivotal aspects, such as proliferation, invasion, metastasis, and drug resistance, in OC. Furthermore, it discusses the potential of m6A-associated regulators as early diagnostic markers and therapeutic targets, thus contributing to the diagnosis and treatment of OC.

Role of N6-methyladenosine methylation in glioma: recent insights and future directions

Glioma is the most pervasive intracranial tumor in the central nervous system (CNS), with glioblastoma (GBM) being the most malignant type having a highly heterogeneous cancer cell population. There is a significantly high mortality rate in GBM patients. Molecular biomarkers related to GBM malignancy may have prognostic values in predicting survival outcomes and therapeutic responses, especially in patients with high-grade gliomas. In particular, N6-methyladenine (m6A) mRNA modification is the most abundant form of post-transcriptional RNA modification in mammals and is involved in regulating mRNA translation and degradation. Cumulative findings indicate that m6A methylation plays a crucial part in neurogenesis and glioma pathogenesis. In this review, we summarize recent advances regarding the functional significance of m6A modification and its regulatory factors in glioma occurrence and progression. Significant advancement of m6A methylation-associated regulators as potential therapeutic targets is also discussed.

New understandings of the genetic regulatory relationship between non-coding RNAs and m6A modification

One of the most frequent epigenetic modifications of RNA in eukaryotes is N6 methyladenosine (m6A), which is mostly present in messenger RNAs. Through the influence of several RNA processing stages, m6A modification is a crucial approach for controlling gene expression, especially in cancer progression. It is universally acknowledged that numerous non-coding RNAs (ncRNAs), such as microRNAs, circular RNAs, long non-coding RNAs, and piRNAs, are also significantly affected by m6A modification, and the complex genetic regulatory relationship between m6A and ncRNAs plays a pivotal role in the development of cancer. The connection between m6A modifications and ncRNAs offers an opportunity to explore the oncogene potential regulatory mechanisms and suggests that m6A modifications and ncRNAs could be vital biomarkers for multiple cancers. In this review, we discuss the mechanisms of interaction between m6A methylation and ncRNAs in cancer, and we also summarize diagnostic and prognostic biomarkers for clinical cancer detection. Furthermore, our article includes some methodologies for identifying m6A sites when assessing biomarker potential.

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.

RNA N6-methyladenosine methylation and skin diseases

Skin diseases are global health issues caused by multiple pathogenic factors, in which epigenetics plays an invaluable role. Post-transcriptional RNA modifications are important epigenetic mechanism that regulate gene expression at the genome-wide level. N6-methyladenosine (m6A) is the most prevalent modification that occurs in the messenger RNAs (mRNA) of most eukaryotes, which is installed by methyltransferases called "writers", removed by demethylases called "erasers", and recognised by RNA-binding proteins called "readers". To date, m6A is emerging to play essential part in both physiological processes and pathological progression, including skin diseases. However, a systematic summary of m6A in skin disease has not yet been reported. This review starts by illustrating each m6A-related modifier specifically and their roles in RNA processing, and then focus on the existing research advances of m6A in immune homeostasis and skin diseases.

Insights into the regulatory role of RNA methylation modifications in glioma

Epitranscriptomic abnormalities, which are highly prevalent in primary central nervous system malignancies, have been identified as crucial contributors to the development and progression of gliomas. RNA epitranscriptomic modifications, particularly the reversible modification methylation, have been observed throughout the RNA cycle. Epitranscriptomic modifications, which regulate RNA transcription and translation, have profound biological implications. These modifications are associated with the development of several cancer types. Notably, three main protein types-writers, erasers, and readers, in conjunction with other related proteins, mediate these epitranscriptomic changes. This review primarily focuses on the role of recently identified RNA methylation modifications in gliomas, such as N6-methyladenosine (m6A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), and N1-methyladenosine (m1A). We delved into their corresponding writers, erasers, readers, and related binding proteins to propose new approaches and prognostic indicators for patients with glioma.

LncRNA FTO-IT1 promotes glycolysis and progression of hepatocellular carcinoma through modulating FTO-mediated N6-methyladenosine modification on GLUT1 and PKM2

BACKGROUND

Long non-coding RNAs (LncRNAs) have been extensively studied to play essential roles in tumor progression. However, more in-depth studies are waiting to be solved on how lncRNAs regulate the progression of hepatocellular carcinoma (HCC).

METHODS

Different expression levels of lncRNAs in HCC cells were compared by analysis of Gene Expression Omnibus and The Cancer Genome Atlas databases. The effects of lncRNA FTO Intronic Transcript 1 (FTO-IT1) on HCC cells were assessed by gain- and loss-of-function experiments. Colony formation assay, Edu assay, glucose uptake and lactic acid production assay were performed to evaluate the regulation of proliferation and glycolysis of HCC cells by FTO-IT1. The binding between protein interleukin enhancer binding factor 2/3 (ILF2/ILF3) and FTO-IT1 was determined by RNA pull-down, mass spectroscopy and RNA immunoprecipitation experiments. RNA stability assay, quantitative reverse transcription PCR and Western blot were employed to determine the regulatory mechanisms of FTO-IT1 on fat mass and obesity-associated (FTO). Methylated RNA immunoprecipitation assay was used to assessed the regulation of key enzymes of glycolysis by FTO. The role of FTO-IT1/FTO in vivo was confirmed via xenograft tumor model.

RESULTS

LncRNA FTO-IT1, an intronic region transcript of FTO gene, was highly expressed in HCC and associated with poor prognosis of patients with HCC. FTO-IT1 was related to proliferation and glycolysis of HCC cells, and contributed to the malignant progression of HCC by promoting glycolysis. Mechanistically, FTO-IT1 induced stabilization of FTO mRNA by recruiting ILF2/ILF3 protein complex to 3'UTR of FTO mRNA. As a demethylase for N6-methyladenosine (m6A), FTO decreased m6A modification on mRNAs of glycolysis associated genes including GLUT1, PKM2, and c-Myc which alleviated the YTH N6-methyladenosine RNA binding protein 2 (YTHDF2)-mediated mRNA degradation. Therefore, the upregulated expression of FTO-IT1 leaded to overexpression of GLUT1, PKM2, and c-Myc by which enhanced glycolysis of HCC. Meanwhile, it was found that c-Myc transcriptional regulated expression of FTO-IT1 by binding to its promoter area under hypo-glucose condition, forming a reciprocal loop between c-Myc and FTO-IT1.

CONCLUSIONS

This study identified an important role of the FTO-IT1/FTO axis mediated m6A modification of glycolytic genes contributed to glycolysis and tumorigenesis of HCC, and FTO-IT1 might be served as a new therapeutic target for HCC.

Epigenetic regulation of temozolomide resistance in human cancers with an emphasis on brain tumors: Function of non-coding RNAs

Brain tumors, which are highly malignant, pose a significant threat to health and often result in substantial rates of mortality and morbidity worldwide. The brain cancer therapy has been challenging due to obstacles such as the BBB, which hinders effective delivery of therapeutic agents. Additionally, the emergence of drug resistance further complicates the management of brain tumors. TMZ is utilized in brain cancer removal, but resistance is a drawback. ncRNAs are implicated in various diseases, and their involvement in the cancer is particularly noteworthy. The focus of the current manuscript is to explore the involvement of ncRNAs in controlling drug resistance, specifically in the context of resistance to the chemotherapy drug TMZ. The review emphasizes the function of ncRNAs, particularly miRNAs, in modulating the growth and invasion of brain tumors, which significantly influences their response to TMZ treatment. Through their interactions with various molecular pathways, miRNAs are modulators of TMZ response. Similarly, lncRNAs also associate with molecular pathways and miRNAs, affecting the efficacy of TMZ chemotherapy. Given their functional properties, lncRNAs can either induce or suppress TMZ resistance in brain tumors. Furthermore, circRNAs, which are cancer controllers, regulate miRNAs by acting as sponges, thereby impacting the response to TMZ chemotherapy. The review explores the correlation between ncRNAs and TMZ chemotherapy, shedding light on the underlying molecular pathways involved in this process.

m6A-regulated tumor glycolysis: new advances in epigenetics and metabolism

Glycolytic reprogramming is one of the most important features of cancer and plays an integral role in the progression of cancer. In cancer cells, changes in glucose metabolism meet the needs of self-proliferation, angiogenesis and lymphangiogenesis, metastasis, and also affect the immune escape, prognosis evaluation and therapeutic effect of cancer. The n6-methyladenosine (m6A) modification of RNA is widespread in eukaryotic cells. Dynamic and reversible m6A modifications are widely involved in the regulation of cancer stem cell renewal and differentiation, tumor therapy resistance, tumor microenvironment, tumor immune escape, and tumor metabolism. Lately, more and more evidences show that m6A modification can affect the glycolysis process of tumors in a variety of ways to regulate the biological behavior of tumors. In this review, we discussed the role of glycolysis in tumor genesis and development, and elaborated in detail the profound impact of m6A modification on different tumor by regulating glycolysis. We believe that m6A modified glycolysis has great significance and potential for tumor treatment.

Methyltransferase-like proteins in cancer biology and potential therapeutic targeting

RNA modification has recently become a significant process of gene regulation, and the methyltransferase-like (METTL) family of proteins plays a critical role in RNA modification, methylating various types of RNAs, including mRNA, tRNA, microRNA, rRNA, and mitochondrial RNAs. METTL proteins consist of a unique seven-beta-strand domain, which binds to the methyl donor SAM to catalyze methyl transfer. The most typical family member METTL3/METTL14 forms a methyltransferase complex involved in N6-methyladenosine (m6A) modification of RNA, regulating tumor proliferation, metastasis and invasion, immunotherapy resistance, and metabolic reprogramming of tumor cells. METTL1, METTL4, METTL5, and METTL16 have also been recently identified to have some regulatory ability in tumorigenesis, and the rest of the METTL family members rely on their methyltransferase activity for methylation of different nucleotides, proteins, and small molecules, which regulate translation and affect processes such as cell differentiation and development. Herein, we summarize the literature on METTLs in the last three years to elucidate their roles in human cancers and provide a theoretical basis for their future use as potential therapeutic targets.

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.

Crosstalk between m6A and coding/non-coding RNA in cancer and detection methods of m6A modification residues

N6-methyladenosine (m6A) is one of the most common and well-known internal RNA modifications that occur on mRNAs or ncRNAs. It affects various aspects of RNA metabolism, including splicing, stability, translocation, and translation. An abundance of evidence demonstrates that m6A plays a crucial role in various pathological and biological processes, especially in tumorigenesis and tumor progression. In this article, we introduce the potential functions of m6A regulators, including "writers" that install m6A marks, "erasers" that demethylate m6A, and "readers" that determine the fate of m6A-modified targets. We have conducted a review on the molecular functions of m6A, focusing on both coding and noncoding RNAs. Additionally, we have compiled an overview of the effects noncoding RNAs have on m6A regulators and explored the dual roles of m6A in the development and advancement of cancer. Our review also includes a detailed summary of the most advanced databases for m6A, state-of-the-art experimental and sequencing detection methods, and machine learning-based computational predictors for identifying m6A sites.

The Regulation of m6A Modification in Glioblastoma: Functional Mechanisms and Therapeutic Approaches

Glioblastoma is the most prevalent primary brain tumour and invariably confers a poor prognosis. The immense intra-tumoral heterogeneity of glioblastoma and its ability to rapidly develop treatment resistance are key barriers to successful therapy. As such, there is an urgent need for the greater understanding of the tumour biology in order to guide the development of novel therapeutics in this field. N6-methyladenosine (m6A) is the most abundant of the RNA modifications in eukaryotes. Studies have demonstrated that the regulation of this RNA modification is altered in glioblastoma and may serve to regulate diverse mechanisms including glioma stem-cell self-renewal, tumorigenesis, invasion and treatment evasion. However, the precise mechanisms by which m6A modifications exert their functional effects are poorly understood. This review summarises the evidence for the disordered regulation of m6A in glioblastoma and discusses the downstream functional effects of m6A modification on RNA fate. The wide-ranging biological consequences of m6A modification raises the hope that novel cancer therapies can be targeted against this mechanism.

Deciphering glioma epitranscriptome: focus on RNA modifications

Gliomas are highly malignant tumors accounting for the majority of brain neoplasms. They are characterized by nuclear atypia, high mitotic rate and cellular polymorphism that often contributes to aggressiveness and resistance to standard therapy. They often associate with challenging treatment approaches and poor outcomes. New treatment strategies or regimens to improve the efficacy of glioma treatment require a deeper understanding of glioma occurrence and development as well as elucidation of their molecular biological characteristics. Recent studies have revealed RNA modifications as a key regulatory mechanism involved in tumorigenesis, tumor progression, immune regulation, and response to therapy. The present review discusses research advances on several RNA modifications involved in glioma progression and tumor microenvironment (TME) immunoregulation as well as in the development of adaptive drug resistance, summarizing current progress on major RNA modification targeting strategies.

Role of N6-methyladenosine modification in central nervous system diseases and related therapeutic agents

N6-methyladenosine (m6A) is a ubiquitous mRNA modification in eukaryotes. m6A occurs through the action of methyltransferases, demethylases, and methylation-binding proteins. m6A methylation of RNA is associated with various neurological disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), depression, cerebral apoplexy, brain injury, epilepsy, cerebral arteriovenous malformations, and glioma. Furthermore, recent studies report that m6A-related drugs have attracted considerable concerns in the therapeutic areas of neurological disorders. Here, we mainly summarized the role of m6A modification in neurological diseases and the therapeutic potential of m6A-related drugs. The aim of this review is expected to be useful to systematically assess m6A as a new potential biomarker and develop innovative modulators of m6A for the amelioration and treatment of neurological disorders.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

RNA N6-methyladenosine modification in regulating cancer stem cells and tumor immune microenvironment and its implication for cancer therapy

Therapy resistance is a well-known phenomenon in cancer treatment. It can be intrinsic or acquired, accountable for frequent tumor relapse and death worldwide. The interplay between cancer cells and their neighboring environment can activate complex signaling mechanisms influencing epigenetic changes and maintain cancer cell survival leading to the malignant phenotype. Cancer stem cells (CSCs) are tumor-initiating cells (TICs) and constitute the primary source of drug resistance and tumor recurrence. Studies have shown that cancer cells exhibit dysregulated RNA N6-methyladenosine (m6A) "writers," "erasers," and "readers" levels after acquiring drug resistance. The present review provides novel insight into the role of m6A modifiers involved in CSC generation, cancer cell proliferation, and therapy resistance. m6A RNA modifications in the cross-talk between CSC and the tumor immune microenvironment (TIME) have also been highlighted. Further, we have discussed the therapeutic potential of targeting m6A machinery for cancer diagnosis and the development of new therapies for cancer treatment.

The potential role of m6A modifications on immune cells and immunotherapy

N6-methyladenosine (m6A), is the most prevalent and reversible post-transcriptional epigenetic modification of RNA in mammals. Dysregulation of m6A modifications impacts RNA procession, degradation, translocation, and translation, disrupting immune cell homeostasis and promoting tumor initiation and development. Here, we discuss an -up-to-date summary of the mechanisms by which m6A modifications regulate immune cell anti-tumor as well as self-homeostasis. We also present how the dysregulation of m6A modifications intrinsic to tumor cells regulates the function of immune cells in the tumor microenvironment. Meanwhile, we described some specific inhibitors targeting m6A modulators and discussed their potential use in cancer treatments.

Roles and therapeutic implications of m6A modification in cancer immunotherapy

Recent studies have demonstrated that N6-methyladenosine (m6A), the most abundant, dynamic, and reversible epigenetic RNA modification in eukaryotes, is regulated by a series of enzymes, including methyltransferases (writers), demethylases (erasers), and m6A recognition proteins (readers). Aberrant regulation of m6A modification is pivotal for tumorigenesis, progression, invasion, metastasis, and apoptosis of malignant tumors. Immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment, as recognized by the 2018 Nobel Prize in Medicine and Physiology. However, not all cancer patients response to ICI therapy, which is thought to be the result of intricate immune escape mechanisms. Recently, numerous studies have suggested a novel role for m6A epigenetic modification in the regulation of tumor immune evasion. Herein, we review the relevant mechanisms of m6A regulators in regulating various key signaling pathways in cancer biology and how m6A epigenetic modifications regulate the expression of immune checkpoints, opening a new window to understand the roles and mechanisms of m6A epigenetic modifications in regulating tumor immune evasion. In addition, we highlight the prospects and development directions of future combined immunotherapy strategies based on m6A modification targeting, providing directions for promoting the treatment outcomes of immune checkpoint inhibitors.

Understanding the Epitranscriptome for Avant-Garde Brain Tumour Diagnostics

RNA modifications are diverse, dynamic, and reversible transcript alterations rapidly gaining attention due to their newly defined RNA regulatory roles in cellular pathways and pathogenic mechanisms. The exciting emerging field of 'epitranscriptomics' is predominantly centred on studying the most abundant mRNA modification, N6-methyladenine (m⁶A). The m⁶A mark, similar to many other RNA modifications, is strictly regulated by so-called 'writer', 'reader', and 'eraser' protein species. The abundance of genes coding for the expression of these regulator proteins and m⁶A levels shows great potential as diagnostic and predictive tools across several cancer fields. This review explores our current understanding of RNA modifications in glioma biology and the potential of epitranscriptomics to develop new diagnostic and predictive classification tools that can stratify these highly complex and heterogeneous brain tumours.

MEIS1 Is a Common Transcription Repressor of the miR-23a and NORHA Axis in Granulosa Cells

MicroRNA-23a (miR-23a) is an endogenous small activating RNA (saRNA) involved in ovarian granulosa cell (GC) apoptosis and sow fertility by activating lncRNA NORHA transcription. Here, we reported that both miR-23a and NORHA were repressed by a common transcription factor MEIS1, which forms a small network regulating sow GC apoptosis. We characterized the pig miR-23a core promoter, and the putative binding sites of 26 common transcription factors were detected in the core promoters of both miR-23a and NORHA. Of them, transcription factor MEIS1 expression was the highest in the ovary, and widely distributed in various ovarian cells, including GCs. Functionally, MEIS1 is involved in follicular atresia by inhibiting GC apoptosis. Luciferase reporter and ChIP assays showed that transcription factor MEIS1 represses the transcription activity of miR-23a and NORHA through direct binding to their core promoters. Furthermore, MEIS1 represses miR-23a and NORHA expression in GCs. Additionally, MEIS1 inhibits the expression of FoxO1, a downstream of the miR-23a/NORHA axis, and GC apoptosis by repressing the miR-23a/NORHA axis. Overall, our findings point to MEIS1 as a common transcription repressor of miR-23a and NORHA, and develop the miR-23a/NORHA axis into a small regulatory network regulating GC apoptosis and female fertility.

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.

Potential medicinal value of N6-methyladenosine in autoimmune diseases and tumours

Autoimmune diseases (ADs) are closely related to malignant tumours. On the one hand, ADs can increase the incidence of tumours; on the other hand, malignant tumours can cause rheumatic disease-like manifestations. With the increasing depth of analysis into the mechanism of N6 -methyladenosine (m6A) modification, it has been found that changes in m6A-related modification enzymes are closely related to the occurrence and development of ADs and malignant tumours. In this review, we explore the pathogenesis of ADs and tumours based on m6A modification. According to systematic assessment of the similarities between ADs and tumours, m6A may represent a common target of both diseases. At present, most of the drugs targeting m6A are in the research and development stage, not in clinical trials. Therefore, advancing the development of drugs targeting m6A is of great significance for both the combined treatment of ADs and malignant tumours and improving the quality of life and prognosis of patients.

Recent advances in epigenetic anticancer therapeutics and future perspectives

Tumor development is frequently accompanied by abnormal expression of multiple genomic genes, which can be broadly viewed as decreased expression of tumor suppressor genes and upregulated expression of oncogenes. In this process, epigenetic regulation plays an essential role in the regulation of gene expression without alteration of DNA or RNA sequence, including DNA methylation, RNA methylation, histone modifications and non-coding RNAs. Therefore, drugs developed for the above epigenetic modulation have entered clinical use or preclinical and clinical research stages, contributing to the development of antitumor drugs greatly. Despite the efficacy of epigenetic drugs in hematologic caners, their therapeutic effects in solid tumors have been less favorable. A growing body of research suggests that epigenetic drugs can be applied in combination with other therapies to increase efficacy and overcome tumor resistance. In this review, the progress of epigenetics in tumor progression and oncology drug development is systematically summarized, as well as its synergy with other oncology therapies. The future directions of epigenetic drug development are described in detail.

Genetic and epigenetic defects of the RNA modification machinery in cancer

Cancer was initially considered to be an exclusively genetic disease, but an interplay of dysregulated genetic and epigenetic mechanisms is now known to contribute to the cancer phenotype. More recently, chemical modifications of RNA molecules - the so-called epitranscriptome - have been found to regulate various aspects of RNA function and homeostasis. Specific enzymes, known as RNA-modifying proteins (RMPs), are responsible for depositing, removing, and reading chemical modifications in RNA. Intensive investigations in the epitranscriptomic field in recent years, in conjunction with great technological advances, have revealed the critical role of RNA modifications in regulating numerous cellular pathways. Furthermore, growing evidence has revealed that RNA modification machinery is often altered in human cancers, highlighting the enormous potential of RMPs as pharmacological targets or diagnostic markers.

Recent Advances in RNA m6A Modification in Solid Tumors and Tumor Immunity

An analogous field to epigenetics is referred to as epitranscriptomics, which focuses on the study of post-transcriptional chemical modifications in RNA. RNA molecules, including mRNA, tRNA, rRNA, and other non-coding RNA molecules, can be edited with numerous modifications. The most prevalent modification in eukaryotic mRNA is N6-methyladenosine (m6A), which is a reversible modification found in over 7000 human genes. Recent technological advances have accelerated the characterization of these modifications, and they have been shown to play important roles in many biological processes, including pathogenic processes such as cancer. In this chapter, we discuss the role of m6A mRNA modification in cancer with a focus on solid tumor biology and immunity. m6A RNA methylation and its regulatory proteins can play context-dependent roles in solid tumor development and progression by modulating RNA metabolism to drive oncogenic or tumor-suppressive cellular pathways. m6A RNA methylation also plays dynamic roles within both immune cells and tumor cells to mediate the anti-tumor immune response. Finally, an emerging area of research within epitranscriptomics studies the role of m6A RNA methylation in promoting sensitivity or resistance to cancer therapies, including chemotherapy, targeted therapy, and immunotherapy. Overall, our understanding of m6A RNA methylation in solid tumors has advanced significantly, and continued research is needed both to fill gaps in knowledge and to identify potential areas of focus for therapeutic development.

Biological and pharmacological roles of m6A modifications in cancer drug resistance

Cancer drug resistance represents the main obstacle in cancer treatment. Drug-resistant cancers exhibit complex molecular mechanisms to hit back therapy under pharmacological pressure. As a reversible epigenetic modification, N⁶-methyladenosine (m⁶A) RNA modification was regarded to be the most common epigenetic RNA modification. RNA methyltransferases (writers), demethylases (erasers), and m⁶A-binding proteins (readers) are frequently disordered in several tumors, thus regulating the expression of oncoproteins, enhancing tumorigenesis, cancer proliferation, development, and metastasis. The review elucidated the underlying role of m⁶A in therapy resistance. Alteration of the m⁶A modification affected drug efficacy by restructuring multidrug efflux transporters, drug-metabolizing enzymes, and anticancer drug targets. Furthermore, the variation resulted in resistance by regulating DNA damage repair, downstream adaptive response (apoptosis, autophagy, and oncogenic bypass signaling), cell stemness, tumor immune microenvironment, and exosomal non-coding RNA. It is highlighted that several small molecules targeting m⁶A regulators have shown significant potential for overcoming drug resistance in different cancer categories. Further inhibitors and activators of RNA m⁶A-modified proteins are expected to provide novel anticancer drugs, delivering the therapeutic potential for addressing the challenge of resistance in clinical resistance.

Epigenetic alterations in glioblastomas: Diagnostic, prognostic and therapeutic relevance

Glioblastoma, the most common and heterogeneous tumor affecting brain parenchyma, is dismally characterized by a very poor prognosis. Thus, the search of new, more effective treatments is a vital need. Here, we will review the druggable epigenetic features of glioblastomas that are, indeed, currently explored in preclinical studies and in clinical trials for the development of more effective, personalized treatments. In detail, we will review the studies that have led to the identification of epigenetic signatures, IDH mutations, MGMT gene methylation, histone modification alterations, H3K27 mutations and epitranscriptome landscapes of glioblastomas, in each case discussing the corresponding targeted therapies and their potential efficacy. Finally, we will emphasize how recent technological improvements permit to routinely investigate many glioblastoma epigenetic biomarkers in clinical practice, further enforcing the hope that personalized drugs, targeting specific epigenetic features, could be in future a therapeutic option for selected patients.

An inhibitor of BRD4, GNE987, inhibits the growth of glioblastoma cells by targeting C-Myc and S100A16

PURPOSE

Among children, glioblastomas (GBMs) are a relatively common type of brain tumor. BRD4 expression was elevated in GBM and negatively correlated with the prognosis of glioma. We investigated the anti-GBM effects of a novel BRD4 inhibitor GNE987.

METHODS

We evaluated the anti-tumor effect of GNE987 in vitro and in vivo by Western blot, CCK8, flow cytometry detection, clone formation, the size of xenografts, and Ki67 immunohistochemical staining, and combined ChIP-seq with RNA-seq techniques to find its anti-tumor mechanism.

RESULTS

In vitro experiments showed that GNE987 significantly degraded BRD4, inhibited the proliferation of GBM cells, blocked the cell cycle, and induced apoptosis. Similarly, in vivo experiments, GNE987 also inhibited GBM growth as seen from the size of xenografts and Ki67 immunohistochemical staining. Based on Western blotting, GNE987 can significantly reduce the protein level of C-Myc; meanwhile, we combined ChIP-seq with RNA-seq techniques to confirm that GNE987 downregulated the transcription of S100A16 by disturbing H3K27Ac. Furthermore, we validated that S100A16 is indispensable in GBM growth.

CONCLUSION

GNE987 may be effective against GBM that targets C-Myc expression and influences S100A16 transcription through downregulation of BRD4.

The role of RNA modification in the generation of acquired drug resistance in glioma

Glioma is the most common malignant tumor in the central nervous system. The clinical treatment strategy is mainly surgery combined with concurrent temozolomide chemotherapy, but patients can develop drug resistance during treatment, which severely limits its therapeutic efficacy. Epigenetic regulation at the RNA level is plastic and adaptable, and it can induce a variety of tumor responses to drugs. The regulators of RNA modification include methyltransferases, demethylases, and methylation binding proteins; these are also considered to play an important role in the development, prognosis, and therapeutic response of gliomas, which provides a basis for finding new targets of epigenetic drugs and resetting the sensitivity of tumor cells to temozolomide. This review discusses the relationship between the development of adaptive drug resistance and RNA modification in glioma and summarizes the progress of several major RNA modification strategies in this field, especially RNA m6A modification, m5C modification, and adenosine-to-inosine editing.

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.

Targeting RNA N6-methyladenosine modification: a precise weapon in overcoming tumor immune escape

Immunotherapy, especially immune checkpoint inhibitors (ICIs), has revolutionized the treatment of many types of cancer, particularly advanced-stage cancers. Nevertheless, although a subset of patients experiences dramatic and long-term disease regression in response to ICIs, most patients do not benefit from these treatments. Some may even experience cancer progression. Immune escape by tumor cells may be a key reason for this low response rate. N⁶-methyladenosine (m⁶A) is the most common type of RNA methylation and has been recognized as a critical regulator of tumors and the immune system. Therefore, m⁶A modification and related regulators are promising targets for improving the efficacy of tumor immunotherapy. However, the association between m⁶A modification and tumor immune escape (TIE) has not been comprehensively summarized. Therefore, this review summarizes the existing knowledge regarding m⁶A modifications involved in TIE and their potential mechanisms of action. Moreover, we provide an overview of currently available agents targeting m⁶A regulators that have been tested for their elevated effects on TIE. This review establishes the association between m⁶A modifications and TIE and provides new insights and strategies for maximizing the efficacy of immunotherapy by specifically targeting m⁶A modifications involved in TIE.

Multilevel regulation of N6-methyladenosine RNA modifications: Implications in tumorigenesis and therapeutic opportunities

N⁶-methyladenosine (m⁶A) RNA modification is widely perceived as the most abundant and common modification in transcripts. This modification is dynamically regulated by specific m⁶A "writers", "erasers" and "readers" and is reportedly involved in the occurrence and development of many diseases. Since m⁶A RNA modification was discovered in the 1970s, with the progress of relevant research technologies, an increasing number of functions of m⁶A have been reported, and a preliminary understanding of m⁶A has been obtained. In this review, we summarize the mechanisms through which m⁶A RNA modification is regulated from the perspectives of expression, posttranslational modification and protein interaction. In addition, we also summarize how external and internal environmental factors affect m⁶A RNA modification and its functions in tumors. The mechanisms through which m⁶A methylases, m⁶A demethylases and m⁶A-binding proteins are regulated are complicated and have not been fully elucidated. Therefore, we hope to promote further research in this field by summarizing these mechanisms and look forward to the future application of m⁶A in tumors.

The Role of Non-Coding RNAs in Glioma

For decades, research in cancer biology has been focused on the protein-coding fraction of the human genome. However, with the discovery of non-coding RNAs (ncRNAs), it has become known that these entities not only function in numerous fundamental life processes such as growth, differentiation, and development, but also play critical roles in a wide spectrum of human diseases, including cancer. Dysregulated ncRNA expression is found to affect cancer initiation, progression, and therapy resistance, through transcriptional, post-transcriptional, or epigenetic processes in the cell. In this review, we focus on the recent development and advances in ncRNA biology that are pertinent to their role in glioma tumorigenesis and therapy response. Gliomas are common, and are the most aggressive type of primary tumors, which account for ~30% of central nervous system (CNS) tumors. Of these, glioblastoma (GBM), which are grade IV tumors, are the most lethal brain tumors. Only 5% of GBM patients survive beyond five years upon diagnosis. Hence, a deeper understanding of the cellular non-coding transcriptome might help identify biomarkers and therapeutic agents for a better treatment of glioma. Here, we delve into the functional roles of microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA) in glioma tumorigenesis, discuss the function of their extracellular counterparts, and highlight their potential as biomarkers and therapeutic agents in glioma.