FTO modifies the m6A level of MALAT and promotes bladder cancer progression

The three YTHDF paralogs and VIRMA are strong cross-histotype tumor driver candidates among m6A core genes

N6-Methyladenosine (m6A) is the most abundant internal modification in mRNAs. Despite accumulating evidence for the profound impact of m6A on cancer biology, there are conflicting reports that alterations in genes encoding the m6A machinery proteins can either promote or suppress cancer, even in the same tumor type. Using data from The Cancer Genome Atlas, we performed a pan-cancer investigation of 15 m6A core factors in nearly 10000 samples from 31 tumor types to reveal underlying cross-tumor patterns. Altered expression, largely driven by copy number variations at the chromosome arm level, results in the most common mode of dysregulation of these factors. YTHDF1, YTHDF2, YTHDF3 and VIRMA are the most frequently altered factors and the only ones to be uniquely altered when tumors are grouped according to the expression pattern of the m6A factors. These genes are also the only ones with coherent, pan-cancer predictive power for progression-free survival. On the contrary, METTL3, the most intensively studied m6A factor as a cancer target, shows much lower levels of alteration and no predictive power for patient survival. Therefore, we propose the non-enzymatic YTHDF and VIRMA genes as preferred subjects to dissect the role of m6A in cancer and as priority cancer targets.

LncRNA MALAT1-Targeting Antisense Oligonucleotide Ameliorates the AngII-Induced Vascular Smooth Muscle Cell Proliferation and Migration Through Nrf2/GPX4 Antioxidant Pathway

ABSTRACT

The high level of oxidative stress induced by angiotensin II (AngII) is the main pathophysiological process that promotes the proliferation and migration of vascular smooth muscle cells (VSMCs) and induces vascular remodeling. LncRNA metastasis-related lung adenocarcinoma transcript 1 (MALAT1) has been determined to play an important role in the modulation of oxidative stress and the development of cardiovascular diseases. Nevertheless, the function and underlying mechanism of MALAT1 in restenosis induced by hypertensive angioplasty remain unclear. AngII increased the expression of MALAT1 in VSMCs. We found that antisense oligonucleotide lncRNA MALAT1 (ASO-MALAT1) could inhibit AngII-induced reactive oxygen species production and VSMCs proliferation and migration by inducing the expression of glutathione peroxidase 4 (GPX4), which can be reversed by siRNA-GPX4. GPX4 overexpression can inhibit the proliferation and migration of VSMCs induced by AngII. In addition, we found that the process by which MALAT1 knockdown induces GPX4 expression involves nuclear factor erythrocyte 2-related factor 2 (Nrf2). Overexpression of Nrf2 can increase the expression of GPX4, and downregulation of GPX4 by ML385 (Nrf2 inhibitor) blocked the protective effect of ASO-MALAT1 on AngII-induced proliferation and migration of VSMCs. Ferrostatin-1 (Fer-1, ip 5 mg/kg per day for 2 weeks), a GPX4 agonist, significantly inhibited neointimal formation in spontaneously hypertensive rat by the inhibition of oxidative stress. In conclusion, these data imply that ASO-MALAT1 suppresses the AngII-induced oxidative stress, proliferation, and migration of VSMCs by activating Nrf2/GPX4 antioxidant signaling. GPX4 may be a potential target for the therapeutic intervention of hypertensive vascular restenosis.

m6A-Mediated Induction of 7-Dehydrocholesterol Reductase Stimulates Cholesterol Synthesis and cAMP Signaling to Promote Bladder Cancer Metastasis

Dysregulation of cholesterol homeostasis occurs in multiple types of tumors and promotes cancer progression. Investigating the specific processes that induce abnormal cholesterol metabolism could identify therapeutic targets to improve cancer treatment. In this investigation, we observed upregulation of 7-dehydrocholesterol reductase (DHCR7), a vital enzyme involved in the synthesis of cholesterol, within bladder cancer tissues in comparison to normal tissues, which was correlated with increased bladder cancer metastasis. Increased expression of DHCR7 in bladder cancer was attributed to decreased mRNA degradation mediated by YTHDF2. Loss or inhibition of DHCR7 reduced bladder cancer cell invasion in vitro and metastasis in vivo. Mechanistically, DHCR7 promoted bladder cancer metastasis by activating the cAMP/protein kinase A/FAK pathway. Specifically, DHCR7 increased cAMP levels by elevating cholesterol content in lipid rafts, thereby facilitating the transduction of signaling pathways mediated by cAMP receptors. DHCR7 additionally enhanced the cAMP signaling pathway by reducing the concentration of 7-dehydrocholesterol and promoting the transcription of the G protein-coupled receptor, namely gastric inhibitory polypeptide receptor. Overall, these findings demonstrate that DHCR7 plays an important role in bladder cancer invasion and metastasis by modulating cholesterol synthesis and cAMP signaling. Furthermore, inhibition of DHCR7 shows promise as a viable therapeutic strategy for suppressing bladder cancer invasion and metastasis. Significance: Inhibiting DHCR7 induces cholesterol metabolism reprogramming and lipid raft remodeling to inactivate the cAMP/protein kinase A/FAK axis and suppress bladder cancer metastasis, indicating the therapeutic potential of targeting DHCR7.

The m6A regulators in prostate cancer: molecular basis and clinical perspective

Prostate cancer (PCa) is the second leading cause of cancer-related death among men in western countries. Evidence has indicated the significant role of the androgen receptor (AR) as the main driving factor in controlling the development of PCa, making androgen receptor inhibition (ARI) therapy a pivotal management approach. In addition, AR independent signaling pathways also contribute to PCa progression. One such signaling pathway that has garnered our attention is N6-Methyladenosine (m6A) signaling, which refers to a chemical modification on RNA with crucial roles in RNA metabolism and disease progression, including PCa. It is important to comprehensively summarize the role of each individual m6A regulator in PCa development and understand its interaction with AR signaling. This review aims to provide a thorough summary of the involvement of m6A regulators in PCa development, shedding light on their upstream and downstream signaling pathways. This summary sets the stage for a comprehensive review that would benefit the scientific community and clinical practice by enhancing our understanding of the biology of m6A regulators in the context of PCa.

Higher genetically predicted triglyceride level increases the bladder cancer risk independent of LDL and HDL levels

The causal relationship between lipid levels and bladder cancer is still inconclusive currently. We aimed to reveal the causal relationship between triglycerides, HDL, and LDL and the risk of bladder cancer by univariable and multivariable Mendelian randomization (MR) analysis. The single nucleotide polymorphisms (SNPs) of exposure (triglycerides: 441,016 samples; HDL: 403,943 samples; LDL: 440,546 samples) were obtained from UK Biobank. The Genetic variation related to bladder cancer included 1554 cases and 359,640 controls. Univariable and multivariable MR methods were conducted with subsequent analysis, and smoking was regarded as a confounder. The inverse-variance weighted (IVW), MR-Egger, weighted-median method, Cochran's Q test, and MR-PRESSO were considered the main MR analysis and sensitivity analysis methods. Univariable MR analysis results suggested the triglycerides level (P = 0.011, OR = 1.001, 95% CI = 1.000-1.002) was causally associated with increased risk of bladder cancer. Multivariable MR results indicated that higher triglyceride levels could still increase the risk of bladder cancer after adjusting the effects of HDL, LDL, and smoking (P = 0.042, OR = 1.001, 95% CI = 1.000-1.002). Our findings supported that triglyceride level is causally associated with an increased risk of bladder cancer independent of LDL and HDL at the genetic level. Timely attention to changes in blood lipid levels might reduce the risk of bladder cancer.

Clinical Perspectives in Epitranscriptomics

Epitranscriptomics, the study of reversible and dynamic chemical marks on the RNA, is rapidly emerging as a pivotal field in post-transcriptional gene expression regulation. Increasing knowledge about epitranscriptomic landscapes implicated in disease pathogenesis proves an invaluable opportunity for the identification of epitranscriptomic biomarkers and the development of new potential therapeutic drugs. Hence, recent advances in the characterization of these marks and associated enzymes in both health and disease blaze a trail toward the use of epitranscriptomics approaches for clinical applications. Here, we review the latest studies to provide a wide and comprehensive perspective of clinical epitranscriptomics and emphasize its transformative potential in shaping future health care paradigms.

RNA N6-methyladenosine modifications in urological cancers: from mechanism to application

The N6-methyladenosine (m6A) modification is the most common modification of messenger RNAs in eukaryotes and has crucial roles in multiple cancers, including in urological malignancies such as renal cell carcinoma, bladder cancer and prostate cancer. The m6A RNA modification is controlled by three types of regulators, including methyltransferases (writers), demethylases (erasers) and RNA-binding proteins (readers), which are responsible for gene regulation at the post-transcriptional level. This Review summarizes the current evidence indicating that aberrant or dysregulated m6A modification is associated with urological cancer development, progression and prognosis. The complex and context-dependent effects of dysregulated m6A modifications in urological cancers are described, along with the potential for aberrantly expressed m6A regulators to provide valuable diagnostic and prognostic biomarkers as well as new therapeutic targets.

FTO promotes the progression of bladder cancer via demethylating m6A modifications in PTPN6 mRNA

Bladder cancer (BC), a highly prevalent malignancy of the urinary system, necessitates further investigation into its progression mechanisms. N6-methyladenosine (m6A) RNA methylation, a prevalent modification in cellular RNA, has been implicated in the tumorigenesis and metastasis of various cancers. In this study, the upregulation of FTO in human BC samples and its association with poor prognosis were demonstrated using immunohistochemistry (IHC) on tissue sections collected from BC patients. The functional role of FTO in promoting the proliferation and metastasis abilities of BC cells was determined using a combination of in vitro and in vivo assays. In vitro, we conducted cell proliferation assays, such as the Cell Counting Kit-8 (CCK-8) assay, and metastasis assays, including the wound healing assay and transwell invasion assay. In vivo, we employed xenograft models to assess tumor growth and metastasis. Furthermore, our investigation into potential FTO targets in BC cells revealed that FTO modifies PTPN6 mRNA, leading to increased stability and expression of PTPN6, thereby enhancing proliferation and metastasis abilities. In conclusion, our findings indicate that FTO serves as an oncogenic factor in BC, suggesting its potential utility as a diagnostic or prognostic biomarker for bladder cancer.

Ferroptosis: a critical mechanism of N6-methyladenosine modification involved in carcinogenesis and tumor progression

Ferroptosis is an iron-dependent regulatory cell necrosis induced by iron overload and lipid peroxidation. It occurs when multiple redox-active enzymes are ectopically expressed or show abnormal function. Hence, the precise regulation of ferroptosis-related molecules is mediated across multiple levels, including transcriptional, posttranscriptional, translational, and epigenetic levels. N6-methyladenosine (m6A) is a highly evolutionarily conserved epigenetic modification in mammals. The m6A modification is commonly linked to tumor proliferation, progression, and therapy resistance because it is involved in RNA metabolic processes. Intriguingly, accumulating evidence suggests that dysregulated ferroptosis caused by the m6A modification drives tumor development. In this review, we summarized the roles of m6A regulators in ferroptosis-mediated malignant tumor progression and outlined the m6A regulatory mechanism involved in ferroptosis pathways. We also analyzed the potential value and application strategies of targeting m6A/ferroptosis pathway in the clinical diagnosis and therapy of tumors.

Palmatine inhibits expression fat mass and obesity associated protein (FTO) and exhibits a curative effect in dextran sulfate sodium (DSS)-induced experimental colitis

BACKGROUND

Ulcerative colitis (UC) is an inflammatory disease whose pathogenesis and mechanisms have not been fully described. The m6A methylation modification is a general mRNA modification in mammalian cells and is closely associated with the onset and progression of inflammatory bowel disease (IBD). Palmatine (PAL) is a biologically active alkaloid with anti-inflammatory and protective effects in animal models of colitis. Accordingly, we examined the role of PAL on colitis by regulating N6-methyladenosine (m6A) methylation.

METHODS

A rat experimental colitis model was established by 5 % dextran sulfate sodium (DSS) in drinking water for seven days, then PAL treatment was administered for seven days. The colonic tissue pathology was assessed using hematoxylin-eosin (HE) and disease activity index (DAI). In in vitro studies, a human, spontaneously immortalized non-cancerous colon mucosal epithelial cell line (NCM460) was exposed to 2 % DSS and treated with PAL and cell viability was assayed using Cell Counting Kit-8 (CCK-8). The levels of tumor necrosis factor α (TNF-α), interleukin (IL)-1β, IL-6, and IL-8 were detected by enzyme-linked immunosorbent assay (ELISA) kits. The level of Zonula occludens-1 (ZO-1) was dectected by immunofluorescence. Transepithelial electrical resistance (TEER) of cells was also assessed. The methyltransferase-like 3 (METTL3), METTL14, AlkB homologate 5 (ALKBH5), and fat mass and obesity-associated protein (FTO) expression levels were assessed by western blotting. The localized expression of m6A was measured by immunofluorescence.

RESULTS

PAL significantly prevented bodyweight loss and shortening of the colon in experimental colitis rats, as well as decreasing the DAI and histological damage scores. Furthermore, PAL inhibited the levels of inflammatory factors (TNF-α, IL-6, IL-8, and IL-1β) in both DSS treated rats and NCM460 cells. In addition, PAL enhanced the expression level of ZO-1, and increased the transepithelial electrical resistance to repaire intestinal barrier dysfunction. Colitis occurred due to decreased m6A levels, and the increased FTO expression led to a colitis phenotype. PAL markedly enhanced the METTL3 and METTL14 expression levels while decreasing ALKBH5 and FTO expression levels.

CONCLUSIONS

The findings demonstrated that PAL improved DSS-induced experimental colitis. This effect was associated with inhibiting FTO expression and regulating m6A methylation.

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.

The relationship between the network of non-coding RNAs-molecular targets and N6-methyladenosine modification in tumors of urinary system

N6-methyladenosine (m6A) methylation, a prevalent eukaryotic post-transcriptional modification, is involved in multiple biological functions, including mediating variable splicing, RNA maturation, transcription, and nuclear export, and also is vital for regulating RNA translation, stability, and cytoplasmic degradation. For example, m6A methylation can regulate pre-miRNA expression by affecting both splicing and maturation. Non-coding RNA (ncRNA), which includes microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), does not encode proteins but has powerful impacts on transcription and translation. Conversely, ncRNAs may impact m6A methylation by affecting the expression of m6A regulators, including miRNAs targeting mRNA of m6A regulators, or lncRNAs, and circRNAs, acting as scaffolds to regulate transcription of m6A regulatory factors. Dysregulation of m6A methylation is common in urinary tumors, and the regulatory role of ncRNAs is also important for these malignancies. This article provides a systematic review of the role and mechanisms of action of m6A methylation and ncRNAs in urinary tumors.

Fat mass and obesity-associated protein (FTO) mediated m6A modification of circFAM192A promoted gastric cancer proliferation by suppressing SLC7A5 decay

Gastric cancer (GC) is a common malignant tumor worldwide, especially in East Asia, with high incidence and mortality rate. Epigenetic modifications have been reported to participate in the progression of gastric cancer, among which m6A is the most abundant and important chemical modification in RNAs. Fat mass and obesity-associated protein (FTO) is the first identified RNA demethylase but little is known about its role in gastric cancer. In our study, data from TCGA and clinical samples showed that FTO was highly expressed in gastric cancer tissues. Kaplan-Meier plotter suggested that patients with the high level of FTO had a poor prognosis. In vitro and in vivo experiments confirmed the role of FTO in promoting gastric cancer cell proliferation. Mechanistically, we found that FTO bound to circFAM192A at the specific site and removed the m6A modification in circFAM192A, protecting it from degradation. CircFAM192A subsequently interacted with the leucine transporter solute carrier family 7 member 5 (SLC7A5) and enhancing its stability. As a result, an increased amount of SLC7A5 was on the membrane, which facilitated leucine uptake and activated the mTOR signaling pathway. Therefore, our study demonstrated that FTO promoted gastric cancer proliferation through the circFAM192A/SLC7A5 axis in the m6A-dependent manner. Our study shed new light on the role of FTO in gastric cancer progression.

Research advances of MAL family members in tumorigenesis and tumor progression (Review)

The myelin and lymphocyte protein (MAL) family is a novel gene family first identified and characterized in 2002. This family is comprised of seven members, including MAL, MAL2, plasmolipin, MALL, myeloid differentiation‑associated marker (MYADM), MYADML2 and CMTM8, which are located on different chromosomes. In addition to exhibiting extensive activity during transcytosis, the MAL family plays a vital role in the neurological, digestive, respiratory, genitourinary and other physiological systems. Furthermore, the intimate association between MAL and the pathogenesis, progression and metastasis of malignancies, attributable to several mechanisms such as DNA methylation has also been elucidated. In the present review, an overview of the structural and functional properties of the MAL family and the latest research findings regarding the relationship between several MAL members and various cancers is provided. Furthermore, the potential clinical and scientific significance of MAL is discussed and directions for future research are summarized.

N6-methyladenosine demethyltransferase FTO mediated m6A modification of estrogen receptor alpha in non-small cell lung cancer tumorigenesis

Fat mass and obesity-associated protein (FTO), which is closely linked with obesity and dietary intake, plays an important role in diet-related metabolic diseases. However, the underlying mechanism of the N6-methyladenosine (m6A) demethyltransferase FTO in tumor development and progression remains largely unexplored. Here, we demonstrated that FTO expression was largely lower in non-small cell lung cancer (NSCLC) samples than in adjacent healthy tissues, and its expression negatively correlated with poor prognosis. Gain- and loss-of-function assays revealed that FTO inhibited NSCLC tumor cell growth and metastasis in vitro and in vivo. Mechanistically, estrogen receptor alpha (ESR1) is a target of FTO, and increased FTO expression significantly impaired the m6A levels of ESR1 mRNA. There were two clear m6A modification sites (5247A and 5409A) in the 3' untranslated region (3'UTR) of ESR1, and FTO could decrease their methylation. Moreover, the m6A readers YTHDF1 and IGF2BP3 recognized and bound the m6A sites in ESR1 mRNA, thereby enhancing its stability and facilitating tumor growth. We also showed that ESR1 has good diagnostic value for NSCLC. In conclusion, we uncovered an important mechanism of epitranscriptomic regulation by the FTO-YTHDF1-IGF2BP3-ESR1 axis and identified the potential of m6A-dependent therapeutic strategies for NSCLC.

Long non-coding RNA GATA6-AS1 is mediated by N6-methyladenosine methylation and inhibits the proliferation and metastasis of gastric cancer

BACKGROUND

Through experimental research on the biological function of GATA6-AS1, it was confirmed that GATA6-AS1 can inhibit the proliferation, invasion, and migration of gastric cancer cells, suggesting that GATA6-AS1 plays a role as an anti-oncogene in the occurrence and development of gastric cancer. Further experiments confirmed that the overexpression of fat mass and obesity-associated protein (FTO) inhibited the expression of GATA6-AS1, thereby promoting the occurrence and development of gastric cancer.

AIM

To investigate the effects of GATA6-AS1 on the proliferation, invasion and migration of gastric cancer cells and its mechanism of action.

METHODS

We used bioinformatics methods to analyze the Cancer Genome Atlas (https://portal.gdc.cancer.gov/. The Cancer Genome Atlas) and download expression data for GATA6-AS1 in gastric cancer tissue and normal tissue. We also constructed a GATA6-AS1 lentivirus overexpression vector which was transfected into gastric cancer cells to investigate its effects on proliferation, migration and invasion, and thereby clarify the expression of GATA6-AS1 in gastric cancer and its biological role in the genesis and development of gastric cancer. Next, we used a database (http://starbase.sysu.edu.cn/starbase2/) to analysis GATA6-AS1 whether by m6A methylation modify regulation and predict the methyltransferases that may methylate GATA6-AS1. Furthermore, RNA immunoprecipitation experiments confirmed that GATA6-AS1 was able to bind to the m6A methylation modification enzyme. These data allowed us to clarify the ability of m6A methylase to influence the action of GATA6-AS1 and its role in the occurrence and development of gastric cancer.

RESULTS

Low expression levels of GATA6-AS1 were detected in gastric cancer. We also determined the effects of GATA6-AS1 overexpression on the biological function of gastric cancer cells. GATA6-AS1 had strong binding ability with the m6A demethylase FTO, which was expressed at high levels in gastric cancer and negatively correlated with the expression of GATA6-AS1. Following transfection with siRNA to knock down the expression of FTO, the expression levels of GATA6-AS1 were up-regulated. Finally, the proliferation, migration and invasion of gastric cancer cells were all inhibited following the knockdown of FTO expression.

CONCLUSION

During the occurrence and development of gastric cancer, the overexpression of FTO may inhibit the expression of GATA6-AS1, thus promoting the proliferation and metastasis of gastric cancer.

Non-coding RNA-Mediated N6-Methyladenosine (m6A) deposition: A pivotal regulator of cancer, impacting key signaling pathways in carcinogenesis and therapy response

The emergence of RNA modifications has recently been considered as critical post-transcriptional regulations which governed gene expression. N6-methyladenosine (m6A) modification is the most abundant type of RNA modification which is mediated by three distinct classes of proteins called m6A writers, readers, and erasers. Accumulating evidence has been made in understanding the role of m6A modification of non-coding RNAs (ncRNAs) in cancer. Importantly, aberrant expression of ncRNAs and m6A regulators has been elucidated in various cancers. As the key role of ncRNAs in regulation of cancer hallmarks is well accepted now, it could be accepted that m6A modification of ncRNAs could affect cancer progression. The present review intended to discuss the latest knowledge and importance of m6A epigenetic regulation of ncRNAs including mircoRNAs, long non-coding RNAs, and circular RNAs, and their interaction in the context of cancer. Moreover, the current insight into the underlying mechanisms of therapy resistance and also immune response and escape mediated by m6A regulators and ncRNAs are discussed.

LncRNA GAS5 regulated by FTO-mediated m6A demethylation promotes autophagic cell death in NSCLC by targeting UPF1/BRD4 axis

Long non-coding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) has been shown to be a regulator for many cancers, including non-small cell lung cancer (NSCLC). Therefore, its role and mechanism in the process of NSCLC deserve to be further revealed. The expression levels of GAS5, fat mass and obesity-associated protein (FTO) and bromodomain-containing protein 4 (BRD4) were detected by quantitative real-time PCR. Western blot analysis was used to examine the protein expression of FTO, BRD4, up-frameshift protein 1 (UPF1) and autophagy-related markers. Methylated RNA immunoprecipitation was used to assess the m6A level of GAS5 regulated by FTO. Cell proliferation and apoptosis were determined using MTT assay, EdU assay and flow cytometry. Autophagy ability was assessed by immunofluorescence staining and transmission electron microscope. Xenograft tumor model was constructed to explore the effects of FTO and GAS5 on NSCLC tumor growth in vivo. The interaction between UPF1 and GAS5 or BRD4 was confirmed by pull-down assay, RIP assay, dual-luciferase reporter assay, and chromatin immunoprecipitation. Fluorescent in situ hybridization was used to analyze the co-localization of GAS5 and UPF1. Actinomycin D treatment was employed to evaluate BRD4 mRNA stability. GAS5 was downregulated in NSCLC tissues and was associated with poor prognosis in NSCLC patients. FTO was highly expressed in NSCLC, and it inhibited GAS5 expression by reducing GAS5 m6A methylation level. GAS5 suppressed by FTO could promote the autophagic death of NSCLC cells in vitro and inhibit NSCLC tumor growth in vivo. In addition, GAS5 was able to interact with UPF1 to reduce the mRNA stability of BRD4. Knockdown of BRD4 reversed the inhibition of GAS5 or UPF1 silencing on the autophagic cell death of NSCLC. The findings of the study showed that lncRNA GAS5 mediated by FTO could contribute to the autophagic cell death of NSCLC by interacting with UPF1 to reduce BRD4 mRNA stability, suggesting that GAS5 might be a vital therapy target for NSCLC progression.

METTL14 enhances the m6A modification level of lncRNA MSTRG.292666.16 to promote the progression of non-small cell lung cancer

BACKGROUND

m6A modification has close connection with the occurrence, development, and prognosis of tumors. This study aimed to explore the roles of m6A modification and its related mechanisms in non-small cell lung cancer (NSCLC).

METHODS

NSCLC tissues and their corresponding para-cancerous tissues were collected to determine the m6A levels of total RNA/lncRNAs and the expression of m6A modification-related genes/lncRNAs. Then, A549 cells were transfected with si-METTL14 or oe-METTL14, and the cell transfection efficiency was assessed. Subsequently, the viability, apoptosis, cell colony formation, migration and invasion of the different cells were determined. Finally, the nude mouse tumorigenicity experiments were performed to observe the effects of METTL14 in vivo.

RESULTS

Compared to the para-NSCLC tissues, the m6A level and METTL14 expression were both significantly increased in the NSCLC tissues (P < 0.05). Based on the expression of METTL14 in the different cell lines, A549 cells were chosen for further experiments. Then, the A549 cells with METTL14 knockdown and overexpression were successfully established, as well as it was found that METTL14 knockdown could inhibit the viability, colony formation, migration, and invasion of A549 cells, while facilitate their apoptosis. In vivo experiments also showed that METTL14 knockdown could inhibit tumor formation and growth. Additionally, the m6A level of MSTRG.292666.16 was higher in the NSCLC tissues; and after METTL14 knockdown, the expression and m6A level of MSTRG.292666.16 were both significantly reduced in A549 cells, and vice versa.

CONCLUSION

METTL14 may promote the progression of NSCLC through up-regulating MSTRG.292666.16 and enhance its m6A modification level.

METTL16 suppressed the proliferation and cisplatin-chemoresistance of bladder cancer by degrading PMEPA1 mRNA in a m6A manner through autophagy pathway

N6-methyladenosine (m6A) is important in the physiological processes of many species. Methyltransferase-like 16 (METTL16) is a novel discovered m6A methylase, regulating various tumors in an m6A-dependent manner. However, its function in bladder cancer (BLCA) remains largely unclear. In the present study, we found that low expression of METTL16 predicted poor survival in BLCA patients. METTL16 inhibited the proliferation and cisplatin-resistance function of bladder cancer cells in vitro and in vivo. In addition, METTL16 reduced the mRNA stability of prostate transmembrane protein androgen induced-1 (PMEPA1) via binding to its m6A site in the 3'-UTR, thereby inhibited the proliferation of bladder cancer cells and increased the sensitivity of cisplatin through PMEPA1-mediated autophagy pathway. Finally, we found that hypoxia-inducible factor 2α (HIF-2α) exerted its tumor-promoting effect by binding the METTL16 promoter region to repress its transcription. Taken together, High expression of METTL16 predicted better survival in BLCA. METTL16 significantly inhibited bladder cancer cell proliferation and sensitized bladder cancer cells to cisplatin via HIF-2α-METTL16-PMEPA1-autophagy axis in a m6A manner. These findings might provide fresh insights into BLCA therapy.

Targeted m6A demethylation of ITGA6 mRNA by a multisite dCasRx-m6A editor inhibits bladder cancer development

INTRODUCTION

N6-methyladenosine (m6A) modification contributes to the pathogenesis and development of various cancers, including bladder cancer (BCa). In particular, integrin α6 (ITGA6) promotes BCa progression by cooperatively regulating multisite m6A modification. However, the therapeutic effect of targeting ITGA6 multisite m6A modifications in BCa remains unknown.

OBJECTIVES

We aim to develop a multisite dCasRx- m6A editor for assessing the effects of the multisite dCasRx-m6A editor targeted m6A demethylation of ITGA6 mRNA in BC growth and progression.

METHODS

The multisite dCasRx- m6A editor was generated by cloning. m6A-methylated RNA immunoprecipitation (meRIP), luciferase reporter, a single-base T3 ligase-based qPCR-amplification, Polysome profiling and meRIP-seq experiments were performed to determine the targeting specificity of the multisite dCasRx-m6A editor. We performed cell phenotype analysis and used in vivo mouse xenograft models to assess the effects of the multisite dCasRx-m6A editor in BC growth and progression.

RESULTS

We designed a targeted ITGA6 multi-locus guide (g)RNA and established a bidirectional deactivated RfxCas13d (dCasRx)-based m6A-editing platform, comprising a nucleus-localized dCasRx fused with the catalytic domains of methyltransferase-like 3 (METTL3-CD) or α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5-CD), to simultaneously manipulate the methylation of ITGA6 mRNA at four m6A sites. The results confirmed the dCasRx-m6A editor modified m6A at multiple sites in ITGA6 mRNA, with low off-target effects. Moreover, targeted m6A demethylation of ITGA6 mRNA by the multisite dCasRx-m6A editor significantly reduced BCa cell proliferation and migration in vitro and in vivo. Furthermore, the dCasRx-ALKBH5-CD and ITGA6 multi-site gRNA delivered to 5-week-old BALB/cJNju-Foxn1nu/Nju nude mice via adeno-associated viral vectors significantly inhibited BCa cell growth.

CONCLUSION

Our study proposes a novel therapeutic tool for the treatment of BC by applying the multisite dCasRx-m6A editor while highlighting its potential efficacy for treating other diseases associated with abnormal m6A modifications.

Multi-omics comprehensive analysis reveals the predictive value of N6-methyladenosine- related genes in prognosis and immune escape of bladder cancer

BACKGROUND

N6-methyladenosine (m6A) is the most frequent RNA modification in mammals, and its role in bladder cancer (BC) remains rarely revealed.

OBJECTIVE

To predict the value of m6A-related genes in prognosis and immunity in BC.

METHODS

We performed multiple omics analysis of 618 TCGA and GEO patients and used principal component analysis (PCA) to calculate the m6A score for BC patients.

RESULTS

We described the multiple omics status of 23 m6A methylation-related genes (MRGs), and four m6A clusters were identified, which showed significant differences in immune infiltration and biological pathways. Next, we intersected the differential genes among m6A clusters, and 11 survival-related genes were identified, which were used to calculate the m6A score for the patients. We found that the high-score (HS) group showed lower tumor mutation burden (TMB) and TP53 mutations and better prognosis than the low-score (LS) group. Lower immune infiltration, higher expression of PD-L1, PD-1, and CTLA4, and higher immune dysfunction and immune exclusion scores were identified in the LS group, suggesting a higher possibility of immune escape. Finally, the experimental verification shows that the m6A related genes, such as IGFBP1, plays an important role in the growth and metastasis of bladder cancer.

CONCLUSIONS

These findings revealed the important roles of m6A MRGs in predicting prognosis, TMB status, TP53 mutation, immune functions and immunotherapeutic response in BC.

The involvement of MALAT1-ALKBH5 signaling axis into proliferation and metastasis of human papillomavirus-positive cervical cancer

Infection with high-risk human papillomavirus (HPV), for example, with types 16 and 18, is closely associated with cervical cancer development, which continues to threaten women's health globally. Although HPV oncogenes have been recognized as the main cause of transformation of normal cervical epithelial cells, non-coding RNA could also be involved in the initiation and promotion of cervical cancer development. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a well-documented long non-coding RNA (lncRNA), has been previously reported to exert roles in HPV-positive cervical cancer; however, the detailed underlying mechanism has yet to be investigated. In the present study, high expression levels of MALAT1 in HPV-Positive Cervical Cancer cells were confirmed, and silencing MALAT1 resulted in decreased rates of cell proliferation, migration, and invasion, both in vitro and in a zebrafish xenograft tumor model. Moreover, the results obtained showed that silencing MALAT1 led to down-regulation of the N6-methyladenosine (m6A) demethylase ALKBH5 via regulating miR-141-3p expression, which caused a decrease in the expression levels of matrix metalloproteinase 2 (MMP2) and MMP9 expression, thereby suppressing cell migration and invasion. Taken together, the results obtained have suggested that the MALAT-ALKBH5 signaling axis may be activated in HPV-positive cervical cancer cells, which could contribute to cell proliferation and metastasis through the regulation of key genes, such as MMP2 or MMP9. The findings of the present study should both help to improve our understanding of the underlying tumorigenic mechanisms of HPV-positive cervical cancer and be of further use in the development of potential therapeutic drugs.

The role of RNA modification in urological cancers: mechanisms and clinical potential

RNA modification is a post-transcriptional level of regulation that is widely distributed in all types of RNAs, including mRNA, tRNA, rRNA, miRNA, and lncRNA, where N6-methyladenine (m6A) is the most abundant mRNA methylation modification. Significant evidence has depicted that m6A modifications are closely related to human diseases, especially cancer, and play pivotal roles in RNA transcription, splicing, stabilization, and translation processes. The most common urological cancers include prostate, bladder, kidney, and testicular cancers, accounting for a certain proportion of human cancers, with an ever-increasing incidence and mortality. The recurrence, systemic metastasis, poor prognosis, and drug resistance of urologic tumors have prompted the identification of new therapeutic targets and mechanisms. Research on m6A modifications may provide new solutions to the current puzzles. In this review, we provide a comprehensive overview of the key roles played by RNA modifications, especially m6A modifications, in urologic cancers, as well as recent research advances in diagnostics and molecularly targeted therapies.

FTO up-regulation induced by MYC suppresses tumour progression in Epstein-Barr virus-associated gastric cancer

BACKGROUND

Epstein-Barr virus-associated gastric cancer (EBVaGC) is regarded as a distinct molecular subtype of GC, accounting for approximately 9% of all GC cases. Clinically, EBVaGC patients are found to have a significantly lower frequency of lymph node metastasis and better prognosis than uninfected individuals. RNA N6-methyladenosine (m6A) modification has an indispensable role in modulating tumour progression in various cancer types. However, its impact on EBVaGC remains unclear.

METHODS

Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and m6A dot blot were conducted to compare the m6A modification levels between EBVaGC and EBV-negative GC (EBVnGC) cells. Western blot, real-time quantitative PCR (RT-qPCR) and immunohistochemistry were applied to explore the underlying mechanism of the reduced m6A modification in EBVaGC. The biological function of fat mass and obesity-associated protein (FTO) was determined in vivo and in vitro. The target genes of FTO were screened by MeRIP-seq, RT-qPCR and Western blot. The m6A binding proteins of target genes were verified by RNA pulldown and RNA immunoprecipitation assays. Chromatin immunoprecipitation and Luciferase report assays were performed to investigate the mechanism how EBV up-regulated FTO expression.

RESULTS

M6A demethylase FTO was notably increased in EBVaGC, leading to a reduction in m6A modification, and higher FTO expression was associated with better clinical outcomes. Furthermore, FTO depressed EBVaGC cell metastasis and aggressiveness by reducing the expression of target gene AP-1 transcription factor subunit (FOS). Methylated FOS mRNA was specifically recognized by the m6A 'reader' insulin-like growth factor 2 mRNA binding protein 1/2 (IGF2BP1/2), which enhanced its transcripts stability. Moreover, MYC activated by EBV in EBVaGC elevated FTO expression by binding to a specific region of the FTO promoter.

CONCLUSIONS

Mechanistically, our work uncovered a crucial suppressive role of FTO in EBVaGC metastasis and invasiveness via an m6A-FOS-IGF2BP1/2-dependent manner, suggesting a promising biomarker panel for GC metastatic prediction and therapy.

FTO promotes proliferation and migration of bladder cancer via enhancing stability of STAT3 mRNA in an m6A-dependent manner

N6-Methyladenosine (m6A) plays a key role in the occurrence and development of various cancers. Fat mass and obesity-associated protein (FTO) was is involved in multiple cancers owing to its demethylase activity, and the molecular mechanism underlying FTO-promoted bladder cancer proliferation and migration via the regulation of RNA stability requires further investigation. In the present study, FTO was upregulated in bladder cancer and related to poor prognosis. Gain- and loss-of-function experiments showed that the upregulation of FTO promoted bladder cancer proliferation and migration. Mechanistic studies showed that FTO enhanced the stability of signal transducer and activator of transcription 3 (STAT3) mRNA in an m6A-dependent manner, thereby increasing STAT3 expression, which subsequently promoted P-STAT3 expression and activated STAT3 signalling pathway. Overall, this study revealed that the critical role of FTO in the progression of bladder cancer and could provide a novel avenue to regulate oncogene STAT3.

FTO facilitates cancer metastasis by modifying the m6A level of FAP to induce integrin/FAK signaling in non-small cell lung cancer

BACKGROUND

Emerging evidence suggests the critical roles of N6-methyladenosine (m6A) RNA modification in tumorigenesis and tumor progression. However, the role of m6A in non-small cell lung cancer (NSCLC) is still unclear. This study aimed to explore the role of the m6A demethylase fat mass and obesity-associated protein (FTO) in the tumor metastasis of NSCLC.

METHODS

A human m6A epitranscriptomic microarray analysis was used to identify downstream targets of FTO. Quantitative real-time PCR (qRT‒PCR) and western blotting were employed to evaluate the expression levels of FTO and FAP in NSCLC cell lines and tissues. Gain-of-function and loss-of-function assays were conducted in vivo and in vitro to assess the effects of FTO and FAP on NSCLC metastasis. M6A-RNA immunoprecipitation (MeRIP), RNA immunoprecipitation (RIP), luciferase reporter assays, and RNA stability assays were used to explore the mechanism of FTO action. Co-immunoprecipitation (co-IP) assays were used to determine the mechanism of FAP in NSCLC metastasis.

RESULTS

FTO was upregulated and predicted poor prognosis in patients with NSCLC. FTO promoted cell migration and invasion in NSCLC, and the FAK inhibitor defactinib (VS6063) suppressed NSCLC metastasis induced by overexpression of FTO. Mechanistically, FTO facilitated NSCLC metastasis by modifying the m6A level of FAP in a YTHDF2-dependent manner. Moreover, FTO-mediated metastasis formation depended on the interactions between FAP and integrin family members, which further activated the FAK signaling.

CONCLUSION

Our current findings provided valuable insights into the role of FTO-mediated m6A demethylation modification in NSCLC metastasis. FTO was identified as a contributor to NSCLC metastasis through the activation of the FAP/integrin/FAK signaling, which may be a potential therapeutic target for NSCLC. Video Abstract.

Overexpression of FTO inhibits excessive proliferation and promotes the apoptosis of human glomerular mesangial cells by alleviating FOXO6 m6A modification via YTHDF3-dependent mechanisms

Background: N6-methyladenosine (m6A) is a prevalent post-transcriptional modification presented in messenger RNA (mRNA) of eukaryotic organisms. Chronic glomerulonephritis (CGN) is characterised by excessive proliferation and insufficient apoptosis of human glomerular mesangial cells (HGMCs) but its underlying pathogenesis remains undefined. Moreover, the role of m6A in CGN is poorly understood. Methods: The total level of m6A modification was detected using the m6A quantification assay (Colorimetric). Cell proliferation was assessed by EdU cell proliferation assay, and cell apoptosis was detected by flow cytometry. RNA sequencing was performed to screen the downstream target of fat mass and obesity-associated protein (FTO). MeRIP-qPCR was conducted to detect the m6A level of forkhead box o6 (FOXO6) in HGMCs. RIP assay was utilized to indicate the targeting relationship between YTH domain family 3 (YTHDF3) and FOXO6. Actinomycin D assay was used to investigate the stability of FOXO6 in HGMCs. Results: The study found that the expression of FTO was significantly reduced in lipopolysaccharide (LPS)-induced HGMCs and renal biopsy samples of patients with CGN. Moreover, FTO overexpression and knockdown could regulate the proliferation and apoptosis of HGMCs. Furthermore, RNA sequencing and cellular experiments revealed FOXO6 as a downstream target of FTO in regulating the proliferation and apoptosis of HGMCs. Mechanistically, FTO overexpression decreases the level of FOXO6 m6A modification and reduces the stability of FOXO6 mRNA in a YTHDF3-dependent manner. Additionally, the decreased expression of FOXO6 inhibits the PI3K/AKT signaling pathway, thereby inhibiting the proliferation and promoting apoptosis of HGMCs. Conclusion: This study offers insights into the mechanism through which FTO regulates the proliferation and apoptosis of HGMCs by mediating m6A modification of FOXO6 mRNA. These findings also suggest FTO as a potential diagnostic marker and therapeutic target for CGN.

The current landscape of m6A modification in urological cancers

N6-methyladenosine (m6A) methylation is a dynamic and reversible procession of epigenetic modifications. It is increasingly recognized that m6A modification has been involved in the tumorigenesis, development, and progression of urological tumors. Emerging research explored the role of m6A modification in urological cancer. In this review, we will summarize the relationship between m6A modification, renal cell carcinoma, bladder cancer, and prostate cancer, and discover the biological function of m6A regulators in tumor cells. We will also discuss the possible mechanism and future application value used as a potential biomarker or therapeutic target to benefit patients with urological cancers.

The m6A reader YTHDC1-mediated lncRNA CTBP1-AS2 m6A modification accelerates cholangiocarcinoma progression

Background

Cholangiocarcinoma (CCA) is a serious malignancy originating from the bile ducts and the second most common primary liver cancer. Long non-coding RNA (lncRNA) is a functional lncRNA that plays an important role in human cancers. However, the role and underlying mechanisms of CTBP1-AS2 in CCA remain unknown.

Purpose

In this study, we investigated the functional role and mechanism of long-stranded non-coding RNA (lncRNA) C-terminal binding protein 1 antisense RNA 2 (CTBP1-AS2) in CCA progression.

Result

In the present study, the bioinformatics analysis revealed that YTHDC1 and CTBP1-AS2 were significantly upregulated, and it was confirmed in cholangiocarcinoma tissues from CCA patients. Meanwhile, we demonstrated that knockdown of YTHDC1 or lncRNA CTBP1-AS2 inhibited CCA cell proliferation, migration and invasion, blocked the cell cycle in G2/M phase and promoted apoptosis of CCA cells. In addition, lncRNA CTBP1-AS2-mediated N6-methyladenosine (m6A) methylation levels were significantly elevated in cholangiocarcinoma tissues, whereas knockdown of YTHDC1 resulted in a significant down-regulation of m6A methylation levels by lncRNA CTBP1-AS2.

Conclusion

Our results suggest that YTHDC1 affects cholangiocarcinoma progression by modifying the lncRNA CTBP1-AS2 m6A, and CTBP1-AS2 may be a promising therapeutic target for CCA.

FTO-mediated epigenetic upregulation of LINC01559 confers cell resistance to docetaxel in breast carcinoma by suppressing miR-1343-3p

This study was to explore the regulatory effect of long non-coding RNA LINC01559 on Docetaxel resistance in breast carcinoma (BCa) and its underlying mechanism. In the present study, we found that LINC01559 expression was elevated and LINC01559 overexpression facilitated docetaxel resistance in BCa cells. Moreover, it was revealed that the upregulation of LINC01559 in BCa cells was induced by FTO-mediated demethylation in an m6A-YTHDF2-dependent manner. Additionally, Dual-luciferase reporter assay confirmed the binding ability between LINC01559 and miR-1343-3p, and Pearson correlation analysis showed a negative correlation between them. Particularly, miR-1343-3p inhibition partly abolished the suppression on docetaxel resistance in BCa cells caused by LINC01559 knockdown. To sum up, FTO-mediated epigenetic upregulation of LINC01559 promoted cell resistance to Docetaxel in BCa by negatively regulating miR-1343-3p.

FTO promotes cervical cancer cell proliferation, colony formation, migration and invasion via the regulation of the BMP4/Hippo/YAP1/TAZ pathway

Cervical cancer is the fourth most common malignancy tumor worldwide with high incidence and mortality. Accumulating evidence indicated that through an m6A-dependent or m6A-independent mechanism, fat mass and obesity associated gene (FTO) exhibits the tumor-promoting and suppressive roles of FTO involved in various cancers, including cervical cancer. This study aims to verify the biological function and potential mechanisms of FTO in cervical cancer cell proliferation, colony formation, migration, and invasion in vitro as well as tumor growth in vivo. Herein, we confirmed that knockdown of FTO inhibits cell proliferation, colony formation, migration, and invasion of cervical cancer cells in vitro via cell counting kit-8 (CCK8) assay, colony formation assay, and transwell migration and invasion assay. The demethylase activity of FTO is required for cell proliferation, colony formation, migration, and invasion of cervical cancer cells in vitro. RNA sequencing, online database analysis, and western blotting revealed that FTO regulated the BMP4/Hippo/YAP1/TAZ pathway. In addition, FTO upregulates the expression of BMP4 in an m6A-dependent manner and binds to the N-terminal of BMP4 to form a dimer at the C-terminal in cervical cancer cells through protein-protein interaction. We further discovered that BMP4 treatment promoted cell proliferation, colony formation, migration, and invasion of cervical cancer cells, and rescue experiments validated that BMP4 treatment reversed the inhibition of FTO knockdown on the Hippo/YAP1/TAZ pathway and the progression of cervical cancer cells in vitro. Notably, the knockdown of FTO significantly suppressed xenograft tumor growth and the protein level of BMP4 in vivo. Collectively, our results demonstrate that the FTO promotes cervical cancer progression in vitro and in vivo via the regulation of the BMP4/Hippo/YAP1/TAZ pathway, suggesting that FTO acts as an oncogenic molecule and the FTO/BMP4 Hippo/YAP1/TAZ axis may serve as valuable targets for cervical cancer treatment.

The emerging roles and mechanism of N6-methyladenosine (m6A) modifications in urologic tumours progression

Prostate cancer (PCa), bladder cancer (BC), and renal cell cancer (RCC) are the most common urologic tumours in males. N6-methyladenosine (m⁶A), adenosine N6 methylation, is the most prevalent RNA modification in mammals. Increasing evidence suggests that m⁶A plays a crucial role in cancer development. In this review, we comprehensively analyzed the influence of m⁶A methylation on Prostate cancer, bladder cancer, and renal cell cancer and the relationship between the expression of relevant regulatory factors and their development and occurrence, which provides new insights and approaches for the early clinical diagnosis and targeted therapy of urologic malignancies.

The MAL Family of Proteins: Normal Function, Expression in Cancer, and Potential Use as Cancer Biomarkers

The MAL family of integral membrane proteins consists of MAL, MAL2, MALL, PLLP, CMTM8, MYADM, and MYADML2. The best characterized members are elements of the machinery that controls specialized pathways of membrane traffic and cell signaling. This review aims to help answer the following questions about the MAL-family genes: (i) is their expression regulated in cancer and, if so, how? (ii) What role do they play in cancer? (iii) Might they have biomedical applications? Analysis of large-scale gene expression datasets indicated altered levels of MAL-family transcripts in specific cancer types. A comprehensive literature search provides evidence of MAL-family gene dysregulation and protein function repurposing in cancer. For MAL, and probably for other genes of the family, dysregulation is primarily a consequence of gene methylation, although copy number alterations also contribute to varying degrees. The scrutiny of the two sources of information, datasets and published studies, reveals potential prognostic applications of MAL-family members as cancer biomarkers-for instance, MAL2 in breast cancer, MAL2 and MALL in pancreatic cancer, and MAL and MYADM in lung cancer-and other biomedical uses. The availability of validated antibodies to some MAL-family proteins sanctions their use as cancer biomarkers in routine clinical practice.

The Functional Role and Regulatory Mechanism of FTO m6A RNA Demethylase in Human Uterine Leiomyosarcoma

Uterine leiomyosarcoma (uLMS) is the most frequent subtype of uterine sarcoma that presents a poor prognosis and high rates of recurrence and metastasis. The origin and molecular mechanism underlying and driving its clinical and biological behavior remain largely unknown. Recently, we and others have revealed the role of microRNAs, DNA methylation, and histone modifications in contributing to the pathogenesis of uLMS. However, the connection between reversible m6A RNA methylation and uLMS pathogenesis remains unclear. In this study, we assessed the role and mechanism of FTO m6A RNA demethylase in the pathogenesis of uLMS. Immunohistochemistry analysis revealed that the levels of RNA demethylases FTO and ALKBH5 were aberrantly upregulated in uLMS tissues compared to adjacent myometrium with a significant change by histochemical scoring assessment (p < 0.01). Furthermore, the inhibition of FTO demethylase with its small, potent inhibitor (Dac51) significantly decreased the uLMS proliferation dose-dependently via cell cycle arrest. Notably, RNA-seq analysis revealed that the inhibition of FTO with Dac51 exhibited a significant decrease in cell-cycle-related genes, including several CDK members, and a significant increase in the expression of CDKN1A, which correlated with a Dac51-exerted inhibitory effect on cell proliferation. Moreover, Dac51 treatment allowed the rewiring of several critical pathways, including TNFα signaling, KRAS signaling, inflammation response, G2M checkpoint, and C-Myc signaling, among others, leading to the suppression of the uLMS phenotype. Moreover, transcription factor (TF) analyses suggested that epitranscriptional alterations by Dac51 may alter the cell cycle-related gene expression via TF-driven pathways and epigenetic networks in uLMS cells. This intersection of RNA methylation and other epigenetic controls and pathways provides a framework to better understand uterine diseases, particularly uLMS pathogenesis with a dysregulation of RNA methylation machinery. Therefore, targeting the vulnerable epitranscriptome may provide an additional regulatory layer for a promising and novel strategy for treating patients with this aggressive uterine cancer.

FTO-stabilized miR-139-5p targets ZNF217 to suppress prostate cancer cell malignancies by inactivating the PI3K/Akt/mTOR signal pathway

As one of the most important demethylases for RNA N6-methyladenosine (m6A) modifications, fat mass and obesity-associated protein (FTO) plays anti-cancer role during prostate cancer (PC), but it is still unclear the detailed molecular mechanisms. Here, this study verified that FTO inactivated the tumor-accelerating PI3K/Akt/mTOR pathway to hamper PC development through regulating the downstream miR-139-5p/zinc finger protein 217 (ZNF217) axis. Through performing clinical analysis, it was revealed that FTO was apparently ablated in the cancerous tissues compared to the normal tissues collected from PC patients, and patients with high-expressed FTO predicted a favorable prognosis. Functional experiments confirmed that overexpression of FTO suppressed cell proliferation, mitosis, epithelial-mesenchymal transition (EMT), tumorigenesis and lung metastasis both in vitro and in vivo. The following mechanical experiments verified that FTO stabilized miR-139-5p to increase its expression levels in a m6A-dependent manner, and elevated miR-139-5p induced degradation of ZNF217 through binding to ZNF217 mRNA, resulting in the inactivation of the PI3K/Akt/mTOR signal pathway. Finally, our rescuing experiments confirmed that overexpressed FTO-induced tumor-suppressing effects on PC cells were abrogated by miR-139-5p ablation and ZNF217 overexpression. Collectively, this study firstly validated that FTO exerted its anti-tumor effects in PC through regulating the miR-139-5p/ZNF217 axis in a m6A-dependent manner, providing novel biomarkers for the advancement of anti-cancer agents for PC treatment.

YTHDF1 Promotes Bladder Cancer Cell Proliferation via the METTL3/YTHDF1-RPN2-PI3K/AKT/mTOR Axis

N6-methyladenosine (m6A) is the most common mRNA modification and it plays a critical role in tumor progression, prognoses and therapeutic response. In recent years, more and more studies have shown that m6A modifications play an important role in bladder carcinogenesis and development. However, the regulatory mechanisms of m6A modifications are complex. Whether the m6A reading protein YTHDF1 is involved in the development of bladder cancer remains to be elucidated. The aims of this study were to determine the association between METTL3/YTHDF1 and bladder cancer cell proliferation and cisplatin resistance to explore the downstream target genes of METTL3/YTHDF1 and to explore the therapeutic implications for bladder cancer patients. The results showed that the reduced expression of METTL3/YTHDF1 could lead to decreased bladder cancer cell proliferation and cisplatin sensitivity. Meanwhile, overexpression of the downstream target gene, RPN2, could rescue the effect of reduced METTL3/YTHDF1 expression on bladder cancer cells. In conclusion, this study proposes a novel METTL3/YTHDF1-RPN2-PI3K/AKT/mTOR regulatory axis that affects bladder cancer cell proliferation and cisplatin sensitivity.

Epitranscriptic regulation of HRAS by N6-methyladenosine drives tumor progression

Overexpression of Ras, in addition to the oncogenic mutations, occurs in various human cancers. However, the mechanisms for epitranscriptic regulation of RAS in tumorigenesis remain unclear. Here, we report that the widespread N6-methyladenosine (m6A) modification of HRAS, but not KRAS and NRAS, is higher in cancer tissues compared with the adjacent tissues, which results in the increased expression of H-Ras protein, thus promoting cancer cell proliferation and metastasis. Mechanistically, three m6A modification sites of HRAS 3' UTR, which is regulated by FTO and bound by YTHDF1, but not YTHDF2 nor YTHDF3, promote its protein expression by the enhanced translational elongation. In addition, targeting HRAS m6A modification decreases cancer proliferation and metastasis. Clinically, up-regulated H-Ras expression correlates with down-regulated FTO and up-regulated YTHDF1 expression in various cancers. Collectively, our study reveals a linking between specific m6A modification sites of HRAS and tumor progression, which provides a new strategy to target oncogenic Ras signaling.

The role of demethylase AlkB homologs in cancer

The AlkB family (ALKBH1-8 and FTO), a member of the Fe (II)- and α-ketoglutarate-dependent dioxygenase superfamily, has shown the ability to catalyze the demethylation of a variety of substrates, including DNA, RNA, and histones. Methylation is one of the natural organisms’ most prevalent forms of epigenetic modifications. Methylation and demethylation processes on genetic material regulate gene transcription and expression. A wide variety of enzymes are involved in these processes. The methylation levels of DNA, RNA, and histones are highly conserved. Stable methylation levels at different stages can coordinate the regulation of gene expression, DNA repair, and DNA replication. Dynamic methylation changes are essential for the abilities of cell growth, differentiation, and division. In some malignancies, the methylation of DNA, RNA, and histones is frequently altered. To date, nine AlkB homologs as demethylases have been identified in numerous cancers’ biological processes. In this review, we summarize the latest advances in the research of the structures, enzymatic activities, and substrates of the AlkB homologs and the role of these nine homologs as demethylases in cancer genesis, progression, metastasis, and invasion. We provide some new directions for the AlkB homologs in cancer research. In addition, the AlkB family is expected to be a new target for tumor diagnosis and treatment.

m5C-dependent cross-regulation between nuclear reader ALYREF and writer NSUN2 promotes urothelial bladder cancer malignancy through facilitating RABL6/TK1 mRNAs splicing and stabilization

The significance of 5-methylcytosine (m⁵C) methylation in human malignancies has become an increasing focus of investigation. Here, we show that m⁵C regulators including writers, readers and erasers, are predominantly upregulated in urothelial carcinoma of the bladder (UCB) derived from Sun Yat-sen University Cancer Center and The Cancer Genome Atlas cohort. In addition, NOP2/Sun RNA methyltransferase family member 2 (NSUN2) as a methyltransferase and Aly/REF export factor (ALYREF) as a nuclear m⁵C reader, are frequently coexpressed in UCB. By applying patient-derived organoids model and orthotopic xenograft mice model, we demonstrate that ALYREF enhances proliferation and invasion of UCB cells in an m⁵C-dependent manner. Integration of tanscriptome-wide RNA bisulphite sequencing (BisSeq), RNA-sequencing (RNA-seq) and RNA Immunoprecipitation (RIP)-seq analysis revealed that ALYREF specifically binds to hypermethylated m⁵C site in RAB, member RAS oncogene family like 6 (RABL6) and thymidine kinase 1 (TK1) mRNA via its K171 domain. ALYREF controls UCB malignancies through promoting hypermethylated RABL6 and TK1 mRNA for splicing and stabilization. Moreover, ALYREF recognizes hypermethylated m⁵C site of NSUN2, resulting in NSUN2 upregulation in UCB. Clinically, the patients with high coexpression of ALYREF/RABL6/TK1 axis had the poorest overall survival. Our study unveils an m⁵C dependent cross-regulation between nuclear reader ALYREF and m⁵C writer NSUN2 in activation of hypermethylated m⁵C oncogenic RNA through promoting splicing and maintaining stabilization, consequently leading to tumor progression, which provides profound insights into therapeutic strategy for UCB.

The Diagnostic and Therapeutic Role of snoRNA and lincRNA in Bladder Cancer

Bladder cancer is one of the most common malignancies of the urinary tract and can be divided into non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC). Although the means of diagnosis and treatment have continually improved in recent years, the recurrence rate of bladder cancer remains high, and patients with MIBC typically have an unfavourable prognosis and a low quality of life. Emerging evidence demonstrates that long noncoding RNAs play a crucial role in the carcinogenesis and progression of bladder cancer. Long intergenic noncoding RNAs (lincRNAs) are a subgroup of long noncoding RNAs (lncRNAs) that do not overlap protein-coding genes. The potential role of lincRNAs in the regulation of gene expression has been explored in depth in recent years. Small nucleolar RNAs (snoRNAs) are a class of noncoding RNAs (ncRNAs) that mainly exist in the nucleolus, are approximately 60-300 nucleotides in length, and are hosted inside the introns of genes. Small nucleolar RNA host genes (SNHGs) have been associated with the origin and development of bladder cancer. In this review, we aim to comprehensively summarize the biological functions of these molecules in bladder cancer.

Emerging Regulatory Mechanisms of N6-Methyladenosine Modification in Cancer Metastasis

Cancer metastasis is the major cause of cancer-related deaths and accounts for poor therapeutic outcomes. A metastatic cascade is a series of complicated biological processes. N6-methyladenosine (m6A) is the most abundant and conserved epitranscriptomic modification in eukaryotic cells, which has great impacts on RNA production and metabolism, including RNA splicing, processing, degradation and translation. Accumulating evidence demonstrates that m6A plays a critical role in regulating cancer metastasis. However, there is a lack of studies that review the recent advances of m6A in cancer metastasis. Here, we systematically retrieved the functions and mechanisms of how the m6A axis regulates metastasis, and especially summarized the organ-specific liver, lung and brain metastasis mediated by m6A in various cancers. Moreover, we discussed the potential application of m6A modification in cancer diagnosis and therapy, as well as the present limitations and future perspectives of m6A in cancer metastasis. This review provides a comprehensive knowledge on the m6A-mediated regulation of gene expression, which is helpful to extensively understand the complexity of cancer metastasis from a new epitranscriptomic point of view and shed light on the developing novel strategies to anti-metastasis based on m6A alteration.

5'-tRF-GlyGCC promotes breast cancer metastasis by increasing fat mass and obesity-associated protein demethylase activity

tRNA-derived fragments (tRFs) are a class of regulatory non-coding RNAs that play essential biological functions in cancer and stress-induced diseases. Several lines of evidence suggest that 5'-tRF-GlyGCC participates in tumor progression; however, its molecular mechanisms remain unclear. In this study, we explored the function of 5'-tRF-GlyGCC in breast cancer (BC) progression and studied the related potential molecular mechanisms. 5'-tRF-GlyGCC expression increased in human BC, and it promoted the proliferation, migration, and invasion of BC cells in vitro and tumor growth and metastasis in vivo. 5'-tRF-GlyGCC was found for the first time to bind directly to fat mass and obesity-associated proteins, and increase the activity of FTO demethylase, reducing eIF4G1 methylation, inhibiting autophagy, and promoting BC proliferation and metastasis. These findings suggest that 5'-tRF-GlyGCC might be a therapeutic target for treating BC.

RNA N6 -methyladenosine modifications and potential targeted therapeutic strategies in kidney disease

Epigenetic modifications have received increasing attention and have been shown to be extensively involved in kidney development and disease progression. Among them, the most common RNA modification, N⁶ -methyladenosine (m⁶ A), has been shown to dynamically and reversibly exert its functions in multiple ways, including splicing, export, decay and translation initiation efficiency to regulate mRNA fate. Moreover, m⁶ A has also been reported to exert biological effects by destabilizing base pairing to modulate various functions of RNAs. Most importantly, an increasing number of kidney diseases, such as renal cell carcinoma, acute kidney injury and chronic kidney disease, have been found to be associated with aberrant m⁶ A patterns. In this review, we comprehensively review the critical roles of m⁶ A in kidney diseases and discuss the possibilities and relevance of m⁶ A-targeted epigenetic therapy, with an integrated comprehensive description of the detailed alterations in specific loci that contribute to cellular processes that are associated with kidney diseases.

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.

Unraveling the Complex Interactions between the Fat Mass and Obesity-Associated (FTO) Gene, Lifestyle, and Cancer

Carcinogenesis is a complicated process and originates from genetic, epigenetic, and environmental factors. Recent studies have reported a potential critical role for the fat mass and obesity-associated (FTO) gene in carcinogenesis through different signaling pathways such as mRNA N6-methyladenosine (m6A) demethylation. The most common internal modification in mammalian mRNA is the m6A RNA methylation that has significant biological functioning through regulation of cancer-related cellular processes. Some environmental factors, like physical activity and dietary intake, may influence signaling pathways engaged in carcinogenesis, through regulating FTO gene expression. In addition, people with FTO gene polymorphisms may be differently influenced by cancer risk factors, for example, FTO risk allele carriers may need a higher intake of nutrients to prevent cancer than others. In order to obtain a deeper viewpoint of the FTO, lifestyle, and cancer-related pathway interactions, this review aims to discuss upstream and downstream pathways associated with the FTO gene and cancer. The present study discusses the possible mechanisms of interaction of the FTO gene with various cancers and provides a comprehensive picture of the lifestyle factors affecting the FTO gene as well as the possible downstream pathways that lead to the effect of the FTO gene on cancer.

Bioinformatics analysis of the correlation between m6A RNA methylation regulators and the immune infiltration and prognosis of bladder cancer

Background

To analyze the effect of N6-methyladenosine (m6A) RNA methylation regulators on the immune infiltration and prognosis of bladder cancer (BC). We explored the related signaling pathways and prognosis-related genes to provide candidate targets for the treatment and prognostic evaluation of BC.

Methods

After downloading BC data from The Cancer Genome Atlas (TCGA) database, the expressions of m6A-related genes were obtained. We then performed correlation and sample cluster analysis of the m6A methylation regulator genes as well as difference comparison and survival analysis for the clustered patients using R software. Gene set enrichment analysis (GSEA) was carried out on cluster-grouped samples. Finally, the prognosis-related genes of BC among the m6A methylation regulators were screened.

Results

Genomic alterations in the m6A regulators were linked to a poor BC prognosis. HNRNPA2B1, HNRNPC, IGF2BP2, RBM15, YTHDF1, and YTHDF2 were found to be associated with advanced clinical stages of BC. Furthermore, the current study revealed that the levels of the m6A regulators were related to the expression levels and immune infiltration levels of immune regulators [immunosuppressive factors, immunostimulators, and major histocompatibility complex (MHC) molecules] in BC. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses suggested that in addition to the relevant immune responses, m6A regulators were involved in the poor prognosis of BC via their participation in blood vessels through regulatory RNA binding, telomeric DNA binding, microRNA (miRNA) binding, negative regulation of messenger RNA (mRNA) processing, negative regulation of DNA biosynthesis, branches of morphogenesis, positive regulation of the Notch receptor target gene transcription, etc.

Conclusions

The expression of m6A RNA methylation regulators is closely linked to immune infiltration and prognosis in BC. Thus, it can be utilized as a potential molecular target for the treatment and prognostic assessment of BC.

M6A regulator-mediated immune infiltration and methylation modification in hepatocellular carcinoma microenvironment and immunotherapy

Introduction: Tremendous evidence indicates that N6-methyladenosine (m6A) epigenetic modification and m6A-related enzymes constitute a complex network, which jointly regulates prevailing pathological processes and various signaling pathways in humankind. Currently, the role of the m6A-mediated molecular regulatory network in hepatocellular carcinoma (HCC) remains elusive. Methods: We recruited expression and pathological files of 368 HCC patients from The Cancer Genome Atlas cohort. Four public datasets serve as external authentication sets for nearest template prediction (NTP) validation. The correlation between 35 regulators and their prognostic value was compared. Gene set variation analysis (GSVA) was used to explore the latent mechanism. Four independent algorithms (ssGSEA, xCell, MCP-counter, and TIMER) were used to calculate the ratio of tumor cells and non-tumor cells to evaluate the tumor immune microenvironment. The m6Ascore model was established by principal component analysis (PCA). Prediction of immunotherapy and potential drugs was performed using TIDE and SubMap. Results: A total of 35 m6A regulators were widely associated, most of which were risk factors for HCC patients. The m6A phenotypic-cluster revealed differences in regulator transcriptional level, gene mutation frequency, functional pathways, and immune cell infiltration abundance under distinct m6A patterns. As expected, the m6A gene cluster confirmed the aforementioned results. The m6Ascore model further found that patients in the high-m6Ascore group were associated with lower tumor purity, higher enrichment of immune and stromal cells, upregulation of metabolic pathways, lower expression of m6A regulators, and favorable outcomes. Low-m6Ascore patients were associated with adverse outcomes. Notably, low-m6Ascore patients might be more sensitive to anti-PD-L1 therapy. Conclusion: This study found that a classification model based on the m6A manner could predict HCC prognosis and response to immunotherapy for HCC patients, which might improve prognosis and contribute to clinical individualized decision-making.

Translational Regulation by eIFs and RNA Modifications in Cancer

Translation is a fundamental process in all living organisms that involves the decoding of genetic information in mRNA by ribosomes and translation factors. The dysregulation of mRNA translation is a common feature of tumorigenesis. Protein expression reflects the total outcome of multiple regulatory mechanisms that change the metabolism of mRNA pathways from synthesis to degradation. Accumulated evidence has clarified the role of an increasing amount of mRNA modifications at each phase of the pathway, resulting in translational output. Translation machinery is directly affected by mRNA modifications, influencing translation initiation, elongation, and termination or altering mRNA abundance and subcellular localization. In this review, we focus on the translation initiation factors associated with cancer as well as several important RNA modifications, for which we describe their association with cancer.