m6A RNA Research Articles

The significance of m6A RNA methylation regulators in diagnosis and subtype classification of HBV-related hepatocellular carcinoma.

In recent years, abnormal m6A alteration in hepatocellular carcinoma (HCC) has been a focus on investigating the biological implications. In this study, our objective is to determine whether m6A modification contributes to the progression of HBV-related HCC. To achieve this, we employed a random forest model to screen top 8 characteristic m6A regulators from 19 candidate genes. Subsequently, we developed a nomogram model that utilizes these 8 characteristic m6A regulators to predict the prevalence of HBV-related HCC. According to decision curve analysis, patients may benefit from the nomogram model. The clinical impact curves exhibited a robust predictive capability of the nomogram models. Additionally, consensus molecular subtyping was employed to identify m6A modification patterns and m6A-related gene signature. The quantification of immune cell subsets was accomplished through the implementation of ssGSEA algorithms. PCA algorithms were developed to compute the m6A score for individual tumors. Two distinct m6A modification patterns, namely cluster A and cluster B, exhibited significant correlations with distinct immune infiltration patterns and biological pathways. Notably, patients belonging to cluster B demonstrated higher m6A scores compared to those in cluster A, as determined by the m6A score metric. Furthermore, the expression of IGFBP3 proteins was validated through immunofluorescence, revealing their pronounced lower expression in tumor tissues. In summary, our study underscores the importance of m6A modification in the advancement of HBV-related HCC. This research has the potential to yield novel prognostic biomarkers and therapeutic targets for the identification of HBV-related HCC.

RNA m6a Methylation Regulator Expression in Castration-Resistant Prostate Cancer Progression and Its Genetic Associations.

N6-methyladenosine (m6A) methylation, a prevalent epitranscriptomic modification, plays a crucial role in regulating mRNA expression, stability, and translation in mammals. M6A regulators have gained attention for their potential implications in tumorigenesis and clinical applications, such as cancer diagnosis and therapeutics. The existing literature predominantly addresses m6A regulators in the context of primary prostate cancer (PCa). However, a notable gap in the knowledge emerges regarding the dynamic expression patterns of these regulators as PCa progresses towards the castration-resistant stage (CRPC). Employing sequential window acquisition of all theoretical mass spectra (SWATH-MS) and RNAseq analysis, we comprehensively profiled the expression of 27 m6A regulators in hormone/androgen-dependent and -independent PCa cell lines, revealing distinct clustering between tumor and adjacent normal prostate tissues. High-grade PCa tumors demonstrated the upregulation of METTL3, RBM15B, and HNRNAPA2B1 and the downregulation of ZC3H13, NUDT21, and FTO. Notably, we identified six m6A regulators associated with PCa survival. Additionally, association analysis of the PCa-associated risk loci in the cancer genome atlas program (TCGA) data unveiled genetic variations near the WTAP, HNRNPA2B1, and FTO genes as significant expression quantitative trait loci. In summary, our study unraveled abnormalities in m6A regulator expression in PCa progression, elucidating their association with PCa risk loci. Considering the heterogeneity within the PCa phenotypes and treatment responses, our findings suggest that prognostic stratification based on m6A regulator expression could enhance PCa diagnosis and prognosis.

Increased m6A modification of BDNF mRNA via FTO promotes neuronal apoptosis following aluminum-induced oxidative stress

N6-methyladenosine (m6A) RNA modification is a new epigenetic molecular mechanism involved in various biological or pathological processes. Exposure to aluminum (Al) has been considered to promote neuronal apoptosis resulting in cognitive dysfunction, yet whether m6A modification participates in the underlying mechanism remains largely unknown. Here, rats exposed to aluminum-maltolate [Al(mal)3] for 90 days showed impaired learning and memory function and elevated apoptosis, which were related to the increased m6A level and decreased fat mass and obesity-associated protein (FTO, an m6A demethylase) in the hippocampus. Accordingly, similar results presented in PC12 cells following Al(mal)3 treatment and FTO overexpression relieved the increased apoptosis and m6A level in vitro. Next, we identified brain-derived neurotrophic factor (BDNF) as the functional downstream target of FTO in a m6A-dependent manner. Furthermore, it was found that as the onset of aluminum neurotoxicity, oxidative stress may be the upstream regulator of FTO in aluminum-induced apoptosis. Taken together, these results suggest that increased m6A modification of BDNF mRNA via FTO promotes neuronal apoptosis following aluminum-induced oxidative stress.

Abstract 3231: Pharmacological inhibition of the m6A RNA reader, YTHDC1, as a novel approach to targeting biomolecular condensates in cancer

Abstract Epigenetic dysregulation is a hallmark of cancer, and tumors have evolved complex mechanisms to fine-tune oncogenic gene expression. In acute myeloid leukemia (AML), one such regulatory mechanism involves post transcriptional modification of RNAs. The most abundant post transcriptional modification is methylation of adenosine at the N6 position (m6A). This modification is catalyzed by the m6A “writer”, METTL3 and METTL14 complex, and is removed by “erasers” such as FTO and ALKBH5. m6A RNAs can regulate a variety of cellular processes which can impact tumor phenotypes, including RNA stability, splicing, and nuclear export; and METTL3 catalytic inhibitors are currently in clinical development for AML and other cancers (NCT05584111).The m6A “reader”, YTHDC1, has been recognized as a critical contributor to the proliferation and survival of AML cells. As the primary nuclear m6A reader, YTHDC1 localizes with m6A marked RNAs in phase-separated assemblies, termed biomolecular condensates, helping to maintain the stability of oncogenic transcripts such as MYC. Here, we have employed our proprietary microfluidics based screening platform (termed PhaseScanTM) to identify modulators of YTHDC1 biomolecular condensates. Evaluation of early screening hits helped identify that disruption of the interaction between YTHDC1 and m6A RNA is a functionally relevant mechanism of action (MoA) that results in dissolution of YTHDC1 condensates. Using computational and knowledge based approaches, we have identified other structurally distinct inhibitors that occupy the RNA binding pocket of YTHDC1 and disrupt its interaction with m6A RNA at nanomolar potencies. These compounds disrupt cellular YTHDC1 condensates, suppress oncogenic gene expression, and result in anti proliferative and pro-differentiation phenotypes in AML cell lines. Compounds are selective for YTHDC1 over other YTH family members and are also selective in dissolving YTHDC1 condensates over other nuclear and cytosolic condensate systems. Our optimized chemical matter has suitable ADME properties to support in vivo studies. Thus, targeting YTHDC1 biomolecular condensates represents a novel approach to the treatment of AML. Citation Format: Richard C. Centore, Mark Charles, Mansi Arora, Yiwen Chen, Matthew Watson, Charlotte Kelley, Magdalena Czekalska, Marius Rebmann, Mahmoud Ghandi, Jerome Cattin, Nagakumar Bharatham, Prathima Radhakrishnan, Alex Howarth, Gale Rudlaff, William E. Arter, Seema Qamar, Kadi Saar, Douglas Williamson, Andrew Seeber, Tuomas Knowles, Shilpi Arora. Pharmacological inhibition of the m6A RNA reader, YTHDC1, as a novel approach to targeting biomolecular condensates in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3231.

Abstract 7075: Global epitranscriptomic and transcriptomic footprint revealed upregulation of methylated single minded 2-small variant (meSIM2-SV) in colorectal cancer (CRC) by NTMT1(METTL11A) via m6A-YTHDF1-dependent manner

Abstract Establishing global footprint of altered m6A mRNA is a unique method to identify the new prognostics biomarkers. Altered N6-methyladenosine(m6A) RNA methylation regulates cancer progression with uncharacterized mechanism. Here, we present novel link between m6A modification on 5’-UTR SIM2-SV contribution in colorectal cancer progression. MeRIP and RNA-seq data from 68 fresh frozen CRC samples revealed 13,843 altered m6A methylated peaks and found highest in chromosomes 1, 2, and 3. Analysis uncovered 119 overlapping genes and clusters into 32 up-regulated genes with 56 up-hyper peaks, 8 up-regulated genes with 9 up-hypo peaks, 12 down-regulated genes with 14 down-hyper peaks, and 28 down-regulated genes with 40 down-hypo peaks. A significant increase in the SIM2 m6A and RNA level led us to perform correlation analysis between the SIM2SV and m6A RNA regulators. SIM2SV was significantly correlated with YTHDF1 m6A-readers and m6A-NTMT1 writer, suggesting important roles of SIM2SV in CRC oncogenicity. m6A-sequencing identified m6A enrichment in 5’-UTR of SIM2SV gene which further verified. siNTMT1 and siYTHDF1 manipulation in HCT116 and RKO cell lines verified a decrease in SIM2SV gene/protein expression, and m6A level. Knockdown effects also showed decrease in cell proliferation, clonogenicity and induced cell cycle arrest in the G2/M phase for NTMT1 and YTHDF1 versus SIM2 Knockdown showed cell cycle arrest in S/G2 phase. Our investigation revealed the role of new writer NTMT1 for methylated SIM2SV gene expression in colorectal cancer proliferation via m6A-YTHDF1(as “decoder”) dependent manner. Further investigation on m6A modification specifically on SIM2 mRNA revealed the essential roles of its writer NTMT1 and its reader YTHDF1 in CRC development, evidently supporting the importance of the unique landscape of m6A epigenetic modification in colorectal neoplasm, which not only advance our understanding of CRC pathobiology but also provides a new set of molecular targets for building up effective tools to fight CRC. Citation Format: Sudhir Kumar Rai, Ting Gong, Zitong Gao, Yujia Qin, Matthew Huo, Ken Nakastu, Hua Yang, Yuanyuan Fu, Lang Wu, Mayumi Jijiwa, Masaki Nasu, Shaoqiu Chen, Gang Huang, Peiwen Fei, Youping Deng. Global epitranscriptomic and transcriptomic footprint revealed upregulation of methylated single minded 2-small variant (meSIM2-SV) in colorectal cancer (CRC) by NTMT1(METTL11A) via m6A-YTHDF1-dependent manner [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7075.

Abstract 6490: Pt1a and sorafenib combination treatment exerts synergistic anti-hepatocellular carcinoma effect through RNA m6A methylation modification

Abstract Hepatocellular carcinoma (HCC) is the most common type of liver cancer and has a poor prognosis. The survival benefits of sorafenib in patients with advanced HCC are modest owing to acquired resistance. Accumulating evidence has demonstrated that cancer stemness is an important cause of drug resistance and the root cause of tumor recurrence. [PtII(C^N^N)(NHC2Bu)]PF6 (Pt1a) is a newly developed platinum-based drug containing N-heterocyclic carbene with proven anticancer properties against a range of tumor types. However, its role in targeting cancer stemness and its ability to sensitize cancer cells to overcome molecular-targeted therapy drug resistance in HCC remains elusive. Herein, we demonstrate the synergistic inhibitory effect of sorafenib and Pt1a combination treatment on HCC through RNA m6A methylation modification. In cultured HCC cells and patient-derived organoids, the drug combination synergistically reduced the cell viability and promoted cell apoptosis compared to single-drug treatment. Combination treatment also attenuated self-renewal, as evidenced by a marked decrease in tumor-initiating cancer cell frequency, as measured by limiting dilution spheroid formation assay. These findings were further validated in HCC patient-derived xenograft mouse models and a mouse HCC model induced by hydrodynamic tail vein delivery of NRAS+AKT coactivation plasmids. Notably, the combination treatment with sorafenib and Pt1a, but not a single treatment, led to a significant reduction in tumor burden. The combination treatment was also effective in decreasing tumor-initiating cell frequency, as measured by subjecting the harvested tumor cells for limiting dilution spheroid formation assay ex vivo. Mechanistically, integrative RNA-sequencing and thermal proteome profiling analyses both indicated the enrichment of m6A-related pathways in combination drug treatment. An increased global m6A level upon combination treatment was validated using m6A dot blotting, confirming that the synergistic effect may be mediated by the elevated global m6A level in HCC cells. Collectively, our study demonstrated that Pt1a and sorafenib combination treatment synergistically inhibited the viability and stemness of HCC cells by increasing global RNA m6A level. These findings supported the potential of Pt1a as a therapeutic option for HCC and overcoming sorafenib drug resistance. Ongoing studies are focused on identifying m6A regulators and downstream targets involved in combination treatment. Citation Format: Yinjia Huang, Yalu Cui, Ianto Bosheng Huang, Yanyan Wang, Yang Xuan, Pui Ki Wan, Chun Nam Lok, Chi Ming Che, Stephanie Ma. Pt1a and sorafenib combination treatment exerts synergistic anti-hepatocellular carcinoma effect through RNA m6A methylation modification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6490.

Abstract 6847: IGF2BP3 promotes esophageal squamous cell carcinoma progressions via Wnt/CTNNB1 pathway

Abstract The M6A RNA modification plays a crucial role in the progression of tumors. Simultaneously, IGF2BP3 is primarily expressed in the tumor cells of squamous cell carcinoma, rather than in stromal cells, including esophageal squamous cell carcinoma (ESCC), a subtype mainly prevalent in East Asia. However, the mechanism of IGF2BP3 in the progression of esophageal squamous cell carcinoma and its role in the tumor microenvironment (TME) remain unknown and require further exploration. Our research reveals that IGF2BP3 not only plays a significant oncogenic role in tumor cells, including the activation of the Wnt pathway, PI3K-AKT pathway, and MAPK pathway, but also, the high expression of IGF2BP3 is positively correlated with the enrichment of M2 macrophages in ESCC tissues, in the TME, IGF2BP3 promotes the infiltration of M2 macrophages, ultimately facilitating the progression of ESCC. Mechanistically, IGF2BP3 enhances the translation of USP36 mRNA by directly binding to its mRNA, rather than increasing the stability of mRNA. The IGF2BP3-mediated USP36 protein elevation enhances the binding capacity with CTNNB1 protein, reducing its degradation through the ubiquitin-proteasome pathway, and following improved the Wnt/CTNNB1 pathway activating, Ultimate, IGF2BP3 aggravated the malignancy of the tumor. Additionally, the activation of the Wnt pathway promotes TGFB1 transcription and secretion, subsequently activating the polarization of M2 macrophages, infuriating the formation of the tumor immune-suppressive microenvironment, ultimately promoting the progression of esophageal squamous cell carcinoma. Our findings strongly emphasize the oncogenic role of IGF2BP3 in the progression of ESCC both in vitro and in vivo, providing new insights and perspectives for the treatment of esophageal squamous cell carcinoma. Citation Format: Zhongxian Tian, Yongjia Zhou, Yi Ding, Zhengwen Wu, Xiaogang Zhao. IGF2BP3 promotes esophageal squamous cell carcinoma progressions via Wnt/CTNNB1 pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6847.

D-2-HG Inhibits IDH1mut Glioma Growth via FTO Inhibition and Resultant m6A Hypermethylation.

IDH1mut gliomas produce high levels of D-2-HG, an oncometabolite capable of inhibiting α-ketoglutarate-dependent dioxygenases critical to a range of cellular functions involved in gliomagenesis. IDH1mut gliomas also exhibit slower growth rates and improved treatment sensitivity compared to their IDH1wt counterparts. This study explores the mechanism driving apparent reduced growth in IDH1mut gliomas. Specifically, we investigated the relationship between IDH1mut and the RNA m6A demethylases FTO and ALKBH5, and their potential for therapeutic targeting. We investigated the role of D-2-HG and m6A in tumor proliferation/viability using glioma patient tumor samples, patient-derived gliomaspheres, and U87 cells, as well as with mouse intracranial IDH1wt gliomasphere xenografts. MeRIP-Seq RNA sequencing was used to identify m6A enriched transcripts in IDH1mut glioma. We show that IDH1mut production of D-2-HG is capable of reducing glioma cell growth via inhibition of the m6A epitranscriptomic regulator, FTO, with resultant m6A hypermethylation of a set of mRNA transcripts. Based on unbiased MeRIP-Seq epitranscriptomic profiling, we identify ATF5 as a hypermethylated, downregulated transcript that potentially contributes to increased apoptosis. We further demonstrate how targeting this pathway genetically and pharmacologically reduces the proliferative potential of malignant IDH1wt gliomas, both in vitro and in vivo. Our work provides evidence that selective inhibition of the m6A epitranscriptomic regulator FTO attenuates growth in IDH1wt glioma, recapitulating the clinically favorable growth phenotype seen in the IDH1mut subtype.

Abstract 4417: Development of biochemical screening assays to facilitate drug discovery in RNA m6A modification regulators

Abstract Over the recent years, knowledge of RNA modifications and their regulation has expanded extensively, providing novel insights and strategies to explore potential therapeutics for pathogenesis of various diseases, including cancer. Several chemical modifications in RNA have been identified so far, among these N6-methyladenosine (m6A) modification is the most abundant and well-studied epitranscriptomic marker found in mRNA and long noncoding RNA. Abnormal m6A expression is proven to be associated with tumorigenesis, cancer stemness and drug resistance of cancers. Methylation in 6-Adenosin of RNA is a dynamic and reversible process tightly regulated by its writer, m6A methyltransferase complex and erasers, FTO and ALKBH5. m6A methyltransferase complex contains METTL3-METTL14-WTAP as core components. METTL3 is the catalytic component, which is activated by heterodimer formation with METTL14. High METTL3 expression is found in several cancers such as breast, lung, liver, gastric, colorectal, AML and a METTL3 catalytic inhibitor is found to delay AML progression in mouse models. Protein that binds RNA m6A modification to execute it signaling are known as m6A readers. Readers are categorized into three main classes, YTH domain proteins, IGF2 mRNA-binding proteins and heterogeneous nuclear ribonucleoproteins. YTH family readers are found to have oncogenic roles in several cancers including AML, breast, lung, CRC and glioblastoma. Recent studies suggest inhibition of m6A binding of individual YTH family proteins is a promising therapeutic strategy however, potent inhibitors are yet to be identified. This poster summarizes current assays we have developed to facilitate cancer therapeutic discovery in m6A related protein targets. We present development and validation of an assay suitable identify in METTL3 catalytic inhibitors using our proprietary hotspot technology. We also show development of HTRF based biochemical assays for all five YTH family protein YTHDF1-3 and YTHDC1-2, to screen for molecules that disrupt protein-m6A interaction. We further study the selectivity of an FDA approved drug Tegaserod, a reported YTHDF1 inhibitor by a structure based virtual screening, between YTH family proteins. Citation Format: Safnas F. AbdulSalam, Sung Won Oh, Brenna P. Lee, Joseph J. Ferry, John R. Ries, Kurumi Y. Horiuchi. Development of biochemical screening assays to facilitate drug discovery in RNA m6A modification regulators [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4417.

Abstract 7002: RNA m6A modification and lung cancer risk: An epitranscriptome-wide association study

Abstract N6-Methyladenosine (m6A), the most prevalent epitranscriptomic modification in eukaryotic mRNA, determines the fate of target RNAs. Key m6A regulators have been elucidated to be essential for lung cancer cell proliferation. However, the relationship between individual m6A markers and lung cancer risk remains inadequately explored. We conducted an epitranscriptome-wide association study (EpiTWAS) to investigate genetically predicted m6A in association with lung cancer risk. Genetic and m6A data of 30 lung, 12 heart, 28 muscle, and 50 brain tissues from 87 donors predominantly of European ancestry were obtained from Genotype-Tissue Expression (GTEx). For each m6A marker, we built a single-tissue model via elastic net, focusing on lung tissue, and a cross-tissue model through the unified test for molecular signatures (UTMOST) approach, capturing genetic influences on m6A shared by lung and other tissues. SPrediXcan was used to apply these models to data of genome-wide association studies (GWAS) among 38,422 lung cancer cases and 677,930 controls of European descent from International Lung Cancer Consortium (ILCCO), UK Biobank, and FinnGen. For m6A markers significantly associated with lung cancer risk at false discovery rate (FDR)<0.05, we assessed the differential expression of proteins encoded by their target mRNAs in lung cancer versus adjacent normal tissues (200 pairs), using data from Clinical Proteomic Tumor Analysis Consortium (CPTAC). Of the 38,841 high-quality m6A markers in 11,715 genes analyzed, prediction models were built for 6,809 m6A markers in 4,548 genes with performance of R>0.1 (P<0.05), ~85.2% (5,801) of which were single-tissue models. Among these, 28 m6A markers in 26 genes were significantly associated with overall lung cancer risk (FDR<0.05). Notably, 12 (~43%) of these markers in 12 loci are >2 megabases away from any of GWAS-identified lung cancer risk variants. When conditioning on nearby GWAS signals, these 12 associations did not change materially, whereas 15 of the remaining 16 associations lost statistical significance. Analyses by lung cancer histology and smoking status revealed no significant heterogeneity among the 28 associations but identified eight additional m6A markers significantly (FDR<0.05) associated with the risk of adenocarcinoma (n=2), squamous cell carcinoma (n=3), and overall lung cancer among ever- (n=2) or never-smokers (n=1). Of the 33 target RNAs of those 36 m6A markers, 30 encode proteins and 22 of these proteins displayed a significant tumor-normal differential expression at fold change >1.5 and FDR<0.05 in CPTAC lung tissue data. Our study demonstrates the ability of EpiTWAS to decipher GWAS loci and uncover signals potentially missed by GWAS. Our results imply that certain m6A markers may impact lung cancer risk by modulating mRNA translation, underscoring the need for further research to fully unravel the role of m6A in lung cancer etiology. Citation Format: Yaohua Yang, Yaxin Chen, Yawen Qi, Hongmo Liu, Guochong Jia, Jie Ping, Xiao-Ou Shu, Wei Zheng, Weimin Li, Jirong Long, Qiuyin Cai. RNA m6A modification and lung cancer risk: An epitranscriptome-wide association study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7002.

Aminothiazolone Inhibitors Disrupt the Protein-RNA Interaction of METTL16 and Modulate the m6A RNA Modification.

Targeting RNA-binding and modifying proteins via small molecules to modulate post-transcriptional modifications have emerged as a new frontier for chemical biology and therapeutic research. One such RNA-binding protein that regulates the most prevalent eukaryotic RNA modification, N6-methyladenosine (m6A), is the methyltransferase-like protein 16 (METTL16), which plays an oncogenic role in cancers by cofunctioning with other nucleic acid-binding proteins. To date, no potent small-molecule inhibitor of METTL16 or modulator interfering with the METTL16-RNA interaction has been reported and validated, highlighting the unmet need to develop such small molecules to investigate the METTL16-involved regulatory network. Herein, we described the identification of a series of first-in-class aminothiazolone METTL16 inhibitors via a discovery pipeline that started with a fluorescence-polarization (FP)-based screening. Structural optimization of the initial hit yielded inhibitors, such as compound 45, that showed potent single-digit micromolar inhibition activity against the METTL16-RNA binding. The identified aminothiazolone inhibitors can be useful probes to elucidate the biological function of METTL16 upon perturbation and evaluate the therapeutic potential of METTL16 inhibition via small molecules at the post-transcriptional level.

Impaired binding affinity of YTHDC1 with METTL3/METTL14 results in R-loop accumulation in myelodysplastic neoplasms with DDX41 mutation

DEAD box helicase 41 (DDX41) mutations are the most prevalent predisposition to familial myelodysplastic syndrome (MDS). However, the precise roles of these variants in the pathogenesis of MDS have yet to be elucidated. Here, we discovered a novel mechanism by which DDX41 contributes to R-loop-induced DNA damage responses (DDR) in cooperation with the m6A-METTL complex (MAC) and YTHDC1 using DDX41 knockout (KO) and DDX41 knock-in (KI, R525H, Y259C) cell lines as well as primary samples from MDS patients. Compared to wild type (WT), DDX41 KO and KI led to increased levels of m6A RNA methylated R-loop. Interestingly, we found that DDX41 regulates m6A/R-loop levels by interacting with MAC components. Further, DDX41 promoted the recruitment of YTHDC1 to R-loops by promoting the binding between METTL3 and YTHDC1, which was dysregulated in DDX41-deficient cells, contributing to genomic instability. Collectively, we demonstrated that DDX41 plays a key role in the physiological control of R-loops in cooperation with MAC and YTHDC1. These findings provide novel insights into how defects in DDX41 influence MDS pathogenesis and suggest potential therapeutic targets for the treatment of MDS.

Geniposide reduced oxidative stress-induced apoptosis in HK-2 cell through PI3K/AKT3/FOXO1 by m6A modification

Exogenous hydrogen peroxide (H2O2) may generate excessive oxidative stress, inducing renal cell apoptosis related with kidney dysfunction. Geniposide (GP) belongs to the iridoid compound with anti-inflammatory, antioxidant and anti-apoptotic effects. This study aimed to observe the intervention effect of GP on H2O2-induced apoptosis in human kidney-2 (HK-2) cells and to explore its potential mechanism in relation to N6-methyladenosine (m6A) RNA methylation. Cell viability, apotosis rate and cell cycle were tested separately after different treatments. The mRNA and protein levels of m6A related enzymes and phosphoinositide 3-kinase (PI3K)/a serine/threonine-specific protein kinase 3 (AKT3)/forkhead boxo 1 (FOXO1) and superoxide dismutase 2 (SOD2) were detected by reverse transcription-quantitative real-time PCR (RT-qPCR) and Western blot. The whole m6A methyltransferase activity and the m6A content were measured by ELISA-like colorimetric methods. The changes of m6A methylation levels of PI3K/AKT3/FOXO1 and SOD2 were determined by methylated RNA immunoprecipitation (MeRIP)-qPCR. Multiple comparisons were performed by ANOVA with Turkey's post hoc test. Exposed to 400 μmol/L H2O2, cells were arrested in G1 phase and the apoptosis rate increased, which were significantly alleviated by GP. Compared with the H2O2 apoptosis group, both the whole m6A RNA methyltransferase activity and the m6A contents were increased due to GP intervention. Besides, the SOD2 protein was increased, while PI3K and FOXO1 decreased. The m6A methylation level of AKT3 was negatively correlated with its protein level. Taken together, GP affects the global m6A methylation microenvironment and regulates the expression of PI3K/AKT3/FOXO1 signaling pathway via m6A modification, alleviating cell cycle arrest and apoptosis caused by oxidative stress in HK-2 cells with a good application prospect.

RNA m6A Methylation and Alzheimer's Disease: Current Evidence and Future Perspectives

Background: Alzheimer’s disease (AD) is the most common neurodegenerative disease characterized by the pathological accumulation of b-amyloid and neurofibrillary tangles. Despite substantial progress in both basic and clinical research on AD, the detailed mechanism of AD pathogenesis is still elusive. RNA N6-methyladenosine methylation (m6A) is the most predominant post-transcriptional modification on eukaryotic mRNA, prominently enriched in the mammalian brain. Notably, m6A-modified RNA showed significant changes during the development of AD, indicating an important role of this modification in AD pathogenesis. Aim: In this study, we aim to provide a summary of recent advances highlighting the indispensable role of m6A in AD pathogenesis. Result: From the perspective of m6A modification, we review our current understanding of the association between RNA m6A machinery and the risk factors of AD, as well as its involvement in various pathophysiological hallmarks of AD. We also discuss the main obstacles in current studies about m6A in AD pathogenesis and the corresponding caveats and solutions to them. Conclusion: This review emphasizes the significance of investigating m6A in the context of AD and highlights the considerable potential for m6A to emerge as a novel therapeutic target for AD.

The antagonistic effect of FTO on METTL14 promotes AKT3 m6A demethylation and the progression of esophageal cancer

BackgroundAs the most abundant modification in eukaryotic messenger RNAs (mRNAs), N6-methyladenosine (m6A) plays vital roles in many biological processes.MethodsMethylated RNA immunoprecipitation sequencing (MeRIP-seq) and transcriptomic RNA sequencing (RNA-seq) were used to screen for m6A targets in esophageal cancer cells and patients. The role of m6A RNA methylase in esophageal cancer was also analyzed using bioinformatics. In vitro and in vivo experiments were used to analyze gene expression and function. CCK-8, colony formation, cell apoptosis and immunofluorescence staining assays were performed to evaluate the proliferation, migration and invasion of esophageal cancer cells, respectively. Western blot analysis, RNA stability, RIP and luciferase reporter assays were performed to elucidate the underlying mechanism involved.ResultsWe found that the m6A demethylase FTO was significantly upregulated in esophageal cancer cell lines and patient tissues. In vivo and in vitro assays demonstrated that FTO was involved in the proliferation and apoptosis of esophageal cancer cells. Moreover, we found that the m6A methyltransferase METTL14 negatively regulates FTO function in esophageal cancer progression. FTO alone is not related to the prognosis of esophageal cancer, and its function is antagonized by METTL14. By using transcriptome-wide m6A-seq and RNA-seq assays, we revealed that AKT3 is a downstream target of FTO and acts in concert to regulate the tumorigenesis and metastasis of esophageal cancer. Taken together, these findings provide insight into m6A-mediated tumorigenesis in esophageal cancer and could lead to the design of new therapeutic strategies.

Single-Atom Catalysts Mediated Bioorthogonal Modulation of N6-Methyladenosine Methylation for Boosting Cancer Immunotherapy.

Bioorthogonal reactions provide a powerful tool to manipulate biological processes in their native environment. However, the transition-metal catalysts (TMCs) for bioorthogonal catalysis are limited to low atomic utilization and moderate catalytic efficiency, resulting in unsatisfactory performance in a complex physiological environment. Herein, sulfur-doped Fe single-atom catalysts with atomically dispersed and uniform active sites are fabricated to serve as potent bioorthogonal catalysts (denoted as Fe-SA), which provide a powerful tool for in situ manipulation of cellular biological processes. As a proof of concept, the N6-methyladensoine (m6A) methylation in macrophages is selectively regulated by the mannose-modified Fe-SA nanocatalysts (denoted as Fe-SA@Man NCs) for potent cancer immunotherapy. Particularly, the agonist prodrug of m6A writer METTL3/14 complex protein (pro-MPCH) can be activated in situ by tumor-associated macrophage (TAM)-targeting Fe-SA@Man, which can upregulate METTL3/14 complex protein expression and then reprogram TAMs for tumor killing by hypermethylation of m6A modification. Additionally, we find the NCs exhibit an oxidase (OXD)-like activity that further boosts the upregulation of m6A methylation and the polarization of macrophages via producing reactive oxygen species (ROS). Ultimately, the reprogrammed M1 macrophages can elicit immune responses and inhibit tumor proliferation. Our study not only sheds light on the design of single-atom catalysts for potent bioorthogonal catalysis but also provides new insights into the spatiotemporal modulation of m6A RNA methylation for the treatment of various diseases.

M6A RNA methylation regulates mitochondrial function.

RNA methylation of N6-methyladenosine (m6A) is emerging as a fundamental regulator of every aspect of RNA biology. RNA methylation directly impacts protein production to achieve quick modulation of dynamic biological processes. However, whether RNA methylation regulates mitochondrial function is not known, especially in neuronal cells which require a high energy supply and quick reactive responses. Here we show that m6A RNA methylation regulates mitochondrial function through promoting nuclear-encoded mitochondrial complex subunit RNA translation. Conditional genetic knockout of m6A RNA methyltransferase Mettl14 (Methyltransferase like 14) by Nestin-Cre together with metabolomic analysis reveals that Mettl14 knockout-induced m6A depletion significantly downregulates metabolites related to energy metabolism. Furthermore, transcriptome-wide RNA methylation profiling of wild type and Mettl14 knockout mouse brains by m6A-Seq shows enrichment of methylation on mitochondria-related RNA. Importantly, loss of m6A leads to a significant reduction in mitochondrial respiratory capacity and membrane potential. These functional defects are paralleled by the reduced expression of mitochondrial electron transport chain complexes, as well as decreased mitochondrial super-complex assembly and activity. Mechanistically, m6A depletion decreases the translational efficiency of methylated RNA encoding mitochondrial complex subunits through reducing their association with polysomes, while not affecting RNA stability. Together, these findings reveal a novel role for RNA methylation in regulating mitochondrial function. Given that mitochondrial dysfunction and RNA methylation have been increasingly implicate in neurodegenerative disorders, our findings not only provide insights into fundamental mechanisms regulating mitochondrial function, but also open up new avenues for understanding the pathogenesis of neurological diseases.

METTL3 promotes osteogenic differentiation of human umbilical cord mesenchymal stem cells by up-regulating m6A modification of circCTTN.

Human umbilical cord mesenchymal stem cells (hUCMSCs) are promising seed cells in bone tissue engineering. circRNA and N6-methyladenosine (m6A) RNA methylation play important roles in osteogenic differentiation. Here, we investigated the potential relevance of a critical circRNA, hsa_circ_0003376 (circCTTN), and methyltransferase-like 3 (METTL3) in osteogenic differentiation of hUCMSCs. Expression of circCTTN after hUCMSC osteogenic induction was detected by qRT-PCR. Three databases (RMBase v2.0, BERMP, and SRAMP) were used to predict m6A sites of circCTTN. RNA was enriched by methylated RNA immunoprecipitation (MeRIP), followed by quantitative real-time polymerase chain reaction to detect m6A level of circCTTN after METTL3 overexpression and osteogenic induction. RNA pull-down, Western blotting, and protein mass spectrometry were performed to investigate the potential mechanisms by which METTL3 promoted m6A modification of circCTTN. Bioinformatic analyses based on database (STRING) search and co-immunoprecipitation were used to analyze the proteins that interacted with METTL3. Overexpression of METTL3 promoted osteogenic differentiation of hUCMSCs and increased m6A level of circCTTN. Two potential m6A modification sites of circCTTN were predicted. No direct interaction between METTL3 and circCTTN was observed. Thirty-one proteins were pulled down by probes specific for circCTTN, including NOP2, and two m6A reading proteins, EIF3A and SND1. Bioinformatics analysis and co-immunoprecipitation showed that METTL3 interacted with EIF3A indirectly through NOP2. METTL3 promotes the osteogenic differentiation of hUCMSCs by increasing the m6A level of circCTTN. However, METTL3 does not bind directly to circCTTN. METTL3 interacts with circCTTN indirectly through NOP2 and EIF3A.

"Cluster Analysis of RNA m6A Methylation Regulators Based on TCGA and GEO Database in Hepatocellular Carcinoma"

"Cluster Analysis of RNA m6A Methylation Regulators Based on TCGA and GEO Database in Hepatocellular Carcinoma"

The RNA m6A reader IGF2BP3 regulates NFAT1/IRF1 axis-mediated anti-tumor activity in gastric cancer

N6-methyladenosine (m6A) and its associated reader protein insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) are involved in tumor initiation and progression via regulating RNA metabolism. This study aims to investigate the biological function and clinical significance of IGF2BP3 in gastric cancer (GC). The clinical significance of IGF2BP3 was evaluated using tumor related databases and clinical tissues. The biological role and molecular mechanism of IGF2BP3 in GC progression were investigated by multi-omics analysis including Ribosome sequence (Ribo-seq), RNA sequence (RNA-seq) and m6A sequence (m6A-seq) combined with gain- and loss- of function experiments. IGF2BP3 expression is significantly elevated in GC tissues and associated with poor prognosis of GC patients. Knockdown of IGF2BP3 significantly weakens the migration and clonogenic ability, promotes the apoptosis, inhibits translation, and suppresses in vitro growth and progression of GC cells. Mechanistically, IGF2BP3 regulates the mRNA stability and translation of the nuclear factor of activated T cells 1(NFAT1) in a m6A dependent manner. Then NFAT1 induced by IGF2BP3 acts as a transcription factor (TF) to negatively regulates the promoter activities of interferon regulatory factor 1 (IRF1) to inhibit its expression. Inhibition of IGF2BP3-induced expression of IRF1 activates interferon (IFN) signaling pathway and then exerts its anti-tumor effect. Elevated IGF2BP3 promotes in vivo and in vitro GC progression via regulation of NFAT1/IRF1 pathways. Targeted inhibition of IGF2BP3 might be a potential therapeutic approach for GC treatment.