RNA m6A methylation regulates the epithelial mesenchymal transition of cancer cells and translation of Snail

FOXA1-dependent NSUN2 facilitates the advancement of prostate cancer by preserving TRIM28 mRNA stability in a m5C-dependent manner

RNA epigenetics is gaining increased attention for its role in the initiation, metastasis, and drug resistance of tumors. These studies have primarily focused on m6A modification. However, despite being the second most abundant modification found in RNA, the role of m5C modification in prostate cancer remains largely unexplored. Here, we predict an RNA m5C methyltransferase, NSUN2, as a potential therapeutic target for prostate cancer using various bioinformatics approaches, and verify the potential of NSUN2 as a target through multiple preclinical models. Mechanistically, NSUN2 enhances the stability of TRIM28 mRNA by adding m5C modification, promoting the expression of TRIM28. Concurrently, FOXA1, a prostate cancer lineage-specific transcription factor, transcriptionally activates the expression of NSUN2. Our study confirms the clinical potential of targeting RNA epigenetics for the treatment of prostate cancer and elucidates, mechanistically, how RNA epigenetics participates in the complex biological activities within tumors via the FOXA1-NSUN2-TRIM28 axis.

MeRIP-Seq initially revealed the role of m6A modification in Chinese sacbrood virus-infected Apis cerana larvae

Chinese sacbrood virus (CSBV) is highly lethal to honeybee larvae (especially the larva of Apis cerana) and causes considerable losses to beekeeping industry. N6-methyladenine (m6A) modification of mRNA is a predominant post-transcriptional modification in eukaryotes and plays a role in viral infection. However, the role of m6A modification in CSBV infection remains unclear. Herein, we performed high-throughput sequencing for m6A-seq in CSBV-infected and non-infected larvae to investigate host transcriptome-wide m6A modifications and identify m6A-modified genes. A total of 671 variant peaks were identified. Combined analysis of m6A modification and mRNA expression revealed that a significant correlation between mRNA methylation modifications and expression levels observed for 668 Genes. It was proved that CSBV infection can cause important m6A modification changes in host. We examined the effects of CSBV infection on expression of two methylation regulatory genes by qPCR. At the same time, we verified the effect of two methylation regulatory genes on CSBV replication using RNAi technology. This study demonstrated for the first time that CSBV infection can cause m6A modification changes in A. cerana larvae, and comprehensively analyzed the m6A modification pattern of its mRNA, and CSBV infection significantly promoted the expression of AcMETTL3 (Ac represents A. cerana, p = 0.007), but had no effect on the expression of AcMETTL14. It was further confirmed that AcMETTL3 had a significant negative regulatory effect on CSBV replication (p = 0.0432). These results lay a foundation for further exploration of the role of m6A modification in CSBV infection.

M6A-modified BFSP1 induces aerobic glycolysis to promote liver cancer growth and metastasis through upregulating tropomodulin 4

RNA N6-methyladenosine (m6A) is a common RNA modification in eukaryotes, and its abnormal regulation is closely related to cancer progression. Aerobic glycolysis is a main way for cancer cells to obtain energy. It was found that beaded filament structural protein 1 (BFSP1) is a m6A related gene in liver cancer. However, the effect of m6A-modified BFSP1 on aerobic glycolysis and how it is regulated in liver cancer progression have not been explored. Here, we found that BFSP1 was upregulated in liver cancer cells and tissues. Overexpression of BFSP1 promoted the viability, invasion, and aerobic glycolysis of liver cancer cells, whereas knockdown of BFSP1 showed the opposite effects. Co-immunoprecipitation, immunofluorescence and GST pull down analyses showed that BFSP1 directly interacted with tropomodalin 4 (TMOD4), and knockdown of TMOD4 reversed BFSP1 overexpression-induced malignant phenotypes and aerobic glycolysis in liver cancer cells. Moreover, methyltransferase-like 3 (METTL3) enhanced BFSP1 stability by augmenting m6A modification of BFSP1 mRNA, which is achieved in a YTHDF1-dependent manner. In vivo experiments in mice confirmed that METTL3 increased BFSP1 stability by promoting m6A modification of BFSP1 mRNA, and knockdown of BFSP1 inhibited tumor growth and metastasis. In summary, METTL3-mediated m6A methylation of BFSP1 mRNA plays an important role in the aerobic glycolysis and progression of liver cancer, providing a potential therapeutic strategy for liver cancer.

m6A modified ATG9A is required in regulating autophagy to promote HSCs activation and liver fibrosis

Hepatic stellate cells (HSCs) are the central link of the occurrence and development of hepatic fibrosis, and autophagy promotes HSCs activation. N6-methyladenosine (m6A) RNA modification can also control autophagy by targeting selected autophagy-associated genes. but up to now, little research has been done on the m6A modification autophagy-related genes (ATGs) in hepatic fibrosis. Here, we identify ATG9A as a previously unrecognized m6A modified ATG using m6A-sequencing (m6A-seq). Importantly, ATG9A is upregulated in liver fibrosis mice and primary biliary cirrhosis (PBC) patient liver tissue. Mechanistically, based on the presence of m6A binding sites on ATG9A, ATG9A promotes HSCs autophagy in an m6A dependent manner, thereby enhancing HSCs activation. Noteworthy, FTO is identified as the upstream of ATG9A, and knockdown of ATG9A can prevent FTO-induced HSCs autophagy and activation. In bile duct ligation (BDL) or CCL4-induced liver fibrosis mouse models, lowering ATG9A alleviated liver fibrosis through PI3K/AKT/mTOR pathway and TGFβ1/smad3 pathway. Taken together, our results provided that ATG9A is a potential prognostic biomarker and therapeutic target for patients with liver fibrosis.

Bioinformatic Analysis of m6A Regulator-Mediated RNA Methylation Modification Patterns and Immune Microenvironment Characterization in Endometriosis

Epigenetic regulation plays an essential role in immunity and inflammation in endometriosis. In this study, we aimed to explore differences in m6A regulators between endometriosis patients and normal women and analyze the effect of m6A modification on immune and inflammatory microenvironment. The samples for analysis were downloaded from the Gene Expression Omnibus database, including ectopic endometrium (EC), eutopic endometrium (EU), and normal eutopic endometrium (NM) samples from non-endometriosis women. The validation process involved utilizing our previous RNA-sequencing data. Subsequently, a correlation analysis was performed to ascertain the relationship between m6A and the inflammatory microenvironment profile, encompassing infiltrating immunocytes, immune-inflammation reaction gene sets, and human leukocyte antigen genes. LASSO analyses were used to develop risk signature. The findings of this study indicate that the m6A regulators FTO were observed to be significantly up-regulated, while YTHDF2, CBLL1, and METTL3 were down-regulated in endometriosis tissues. The CIBERSORT analysis revealed that the local inflammatory microenvironment of ectopic lesions plays a crucial role in the development of endometriosis. Notably, M2 macrophages exhibited a significant difference between the EC and NM groups. Moreover, M2 macrophages demonstrated a positive correlation with FTO (0.39) and a negative correlation with CBLL1 (- 0.35). Furthermore, consistent clustering of EC and EU samples resulted in the identification of three distinct cell subtypes. Among different cell subtypes, significant differences were in immunoinfiltrating cells, plasma cells, naive CD4 T cells, memory activated CD4 T cells, gamma delta T cells, resting NK cells and activated NK cells but not in macrophages. Furthermore, the identification of various compounds capable of targeting these m6A genes was achieved. In conclusions, our integrated bioinformatics analysis results demonstrated that m6A-related genes METTL3, CBLL1 and YTHDF2 may be useful biomarkers for endometriosis in ectopic endometrium. The potential therapeutic approach of targeting m6A regulators holds promise for the treatment of endometriosis.

Synergistic Target-Attacking Tumor Cells and M2 Macrophages via a Triple-Responsive Nanoassembly for Complete Metastasis Blocking

Collaboration of cancerous cells and microenvironment is the root for tumor spreading, leading to difficulty in complete metastasis blockage via mono-intervention. Herein, a triple-responsive nanoassembly is designed for orienting tumor cells and migration-driving M2 tumor associated macrophages (TAMs) in microenvironment for efficient anti-metastatic therapy. Structurally, a reactive oxygen species (ROS)-responsive crosslinked short-chain polyquaternium is synthesized to bridge graphene oxide (GO) scaffold with apolipoprotein A-I crown via borate-crosslinking, electrostatic adherence, and coordinative coupling. The protein-crowning polymeric GO nanoparticles could give multimodal shielding and triple-responsive release of doxorubicin and Snail-targeted siRNA. Tailor-made apolipoprotein A-I crown fulfills nanoparticles synergistically attacking tumor cells and M2 TAMs via binding with overexpressed scavenger receptors. The findings witness the targeted accumulation and potent cytotoxicity of the hybrid nanoparticles for M2 TAMs and tumor cells; especially, elimination of M2 TAMs in tumor microenvironment holds back Snail-enhancing transforming growth factor (TGF)-β signal pathway, which collaborates with Snail silencing in tumor cells to reverse epithelial mesenchymal transition (EMT) and metastasis-promoting niche. Collectively, the synergistic targeting therapeutic platform could provide a promising solution for metastatic tumor treatment.

METTL3/MYCN cooperation drives neural crest differentiation and provides therapeutic vulnerability in neuroblastoma

Neuroblastoma (NB) is the most common extracranial childhood cancer, caused by the improper differentiation of developing trunk neural crest cells (tNCC) in the sympathetic nervous system. The N6-methyladenosine (m6A) epitranscriptomic modification controls post-transcriptional gene expression but the mechanism by which the m6A methyltransferase complex METTL3/METTL14/WTAP is recruited to specific loci remains to be fully characterized. We explored whether the m6A epitranscriptome could fine-tune gene regulation in migrating/differentiating tNCC. We demonstrate that the m6A modification regulates the expression of HOX genes in tNCC, thereby contributing to their timely differentiation into sympathetic neurons. Furthermore, we show that posterior HOX genes are m6A modified in MYCN-amplified NB with reduced expression. In addition, we provide evidence that sustained overexpression of the MYCN oncogene in tNCC drives METTL3 recruitment to a specific subset of genes including posterior HOX genes creating an undifferentiated state. Moreover, METTL3 depletion/inhibition induces DNA damage and differentiation of MYCN overexpressing cells and increases vulnerability to chemotherapeutic drugs in MYCN-amplified patient-derived xenografts (PDX) in vivo, suggesting METTL3 inhibition could be a potential therapeutic approach for NB.

Lumbrokinase (LK) ameliorates diabetic kidney disease renal fibrosis through regulating snail via m6A RNA methyltransferase 3

The present study was undertaken to investigate the therapeutic effect and underlying mechanisms of lumbrokinase (LK) on diabetic kidney disease (DKD). Kidney tissue samples from DKD patients and normal controls were collected from hospitals. The type 2 diabetic nephropathy model was induced in db/db mice. The mice were then randomly divided into a model group (DM group) and an LK group. db/m mice were used as the control group (Con group). After 12 weeks of treatment with LK (234 KU/kg/day), biochemical parameters were tested, and pathological changes in the kidney were observed under a light microscope. The epithelial-to-mesenchymal transition (EMT), mRNA m6A methylation proteins, and activated TGF-β1/Smad pathway components were assessed by western blot or immunofluorescence in DKD patients, model mice, and high glucose-stimulated HK-2 cells. We found that the m6A eraser METTL3 was expressed at low levels in DKD patients, model mice, and high glucose-stimulated HK-2 cells. METTL3 overexpression reversed the high glucose-induced activation of the TGF-β1/Smad pathway and EMT through snail in vitro. However, LK can restore the expression of the m6A-modifying enzyme METTL3 in vivo and in vitro, suppressed EMT, and alleviated renal interstitial fibrosis by downregulating snail. Overall, LK ameliorated renal fibrosis through the regulation of Snail via m6A RNA METTL3.

YTHDF2 upregulation and subcellular localization dictate CD8 T cell polyfunctionality in anti-tumor immunity

RNA methylation is an important regulatory process to determine immune cell function but how it affects the anti-tumor activity of CD8 T cells is not fully understood. Here we show that the N6-methyladenosine (m6A) RNA reader YTHDF2 is highly expressed in early effector or effector-like CD8 T cells. We find that YTHDF2 facilitates nascent RNA synthesis, and m6A recognition is fundamental for this distinctively nuclear function of the protein, which also reinforces its autoregulation at the RNA level. Loss of YTHDF2 in T cells exacerbates tumor progression and confers unresponsiveness to PD-1 blockade in mice and in humans. In addition to initiating RNA decay that is necessary for mitochondrial fitness, YTHDF2 orchestrates chromatin changes that promote T cell polyfunctionality. YTHDF2 interacts with IKZF1/3, which is important for sustained transcription of their target genes. Accordingly, immunotherapy-induced efficacy could be largely restored in YTHDF2-deficient T cells through combinational use of IKZF1/3 inhibitor lenalidomide in a mouse model. Thus, YTHDF2 coordinates epi-transcriptional and transcriptional networks to potentiate T cell immunity, which could inform therapeutic intervention.

Long non-coding RNAs as the pivotal regulators of epithelial mesenchymal transition through WNT/β-catenin signaling pathway in tumor cells

Tumor cell invasion is considered as one of the main therapeutic challenges in cancer patients, which leads to distant metastasis and reduced prognosis. Therefore, investigation of the factors involved in tumor cell invasion improves the therapeutic methods to reduce tumor metastasis. Epithelial-mesenchymal transition (EMT) process has a pivotal role in tumor cell invasion and metastasis, during which tumor cells gain the invasive ability by losing epithelial characteristics and acquiring mesenchymal characteristics. WNT/β-catenin signaling pathway has a key role in tumor cell invasion by regulation of EMT process. Long non-coding RNAs (lncRNAs) have also an important role in EMT process through the regulation of WNT/β-catenin pathway. Deregulation of lncRNAs is associated with tumor metastasis in different tumor types. Therefore, in the present review, we investigated the role of lncRNAs in EMT process and tumor cell invasion through the regulation of WNT/β-catenin pathway. It has been reported that lncRNAs mainly induced the EMT process and tumor cell invasion through the activation of WNT/β-catenin pathway. LncRNAs that regulate the WNT/β-catenin mediated EMT process can be introduced as the prognostic markers as well as suitable therapeutic targets to reduce the tumor metastasis in cancer patients.

Crosstalk Between m6A RNA Methylation and miRNA Biogenesis in Cancer: An Unholy Nexus

N6-methyladenosine (m6A) is one of the most prevalent internal reversible chemical modification of RNAs in eukaryotes, which has attracted widespread attention recently owing to its regulatory roles in a plethora of normal developmental processes and human diseases like cancer. Deposition of the m6A mark on RNAs is mediated by the dynamic interplay between m6A regulatory proteins such as m6A RNA methyltransferases (m6A writers), m6A RNA demethylases (m6A erasers) and m6A RNA binding proteins (m6A readers). m6A regulators are ectopically expressed in various cancer types, often leading to aberrant expression of tumor-suppressor and oncogenic mRNAs either directly or indirectly via regulating the biogenesis of non-coding RNAs like miRNAs. miRNAs are tiny regulators of gene expression, which often impact various hallmarks of cancer and thus influence tumorigenesis. It is becoming increasingly clear that m6A RNA modification impacts biogenesis and function of miRNAs, and recent studies have interestingly, uncovered many miRNAs whose biogenesis and function are regulated by m6A writers, erasers and readers. In this review, we discuss various mechanisms by which m6A RNA methylation regulates miRNA biogenesis, the functional crosstalk between m6A RNA methylation and miRNAs and how it modulates various aspects of tumorigenesis. The potential of m6A RNA methylation regulated miRNAs as biomarkers and novel therapeutic targets to treat various cancers is also addressed.

FTO/IGF2BP2-mediated N6 methyladenosine modification in invasion and metastasis of thyroid carcinoma via CDH12

Epigenetic reprogramming plays a critical role in cancer progression of cancer, and N6-methyladenosine (m6A) is the most common RNA modification in eukaryotes. The purpose of this study was to explore the related modification mode of m6A regulator construction and evaluate the invasion and migration of thyroid cancer. Our results showed that m6A levels were significantly increased in papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC) samples, which may have been induced by the down-regulation of demethylase fat mass and obesity-associated gene (FTO). Moreover, FTO inhibited PTC and ATC invasion and metastasis through the epithelial-to-mesenchymal transition (EMT) pathway in vivo and in vitro. Mechanistically, an m6A-mRNA epitranscriptomic microarray showed that Cadherin 12 (CDH12) is the key target gene mediated by FTO in an m6A-dependent manner. CDH12 promotes invasion and metastasis through the EMT pathway in thyroid cancer, both in vivo and in vitro. Furthermore, we found that insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) is an important m6A reading protein, that regulates the stability of CDH12 mRNA and mediates EMT progression, thereby promoting the invasion and metastasis of PTC and ATC. Thus, FTO, IGF2BP2 and CDH12 may be effective therapeutic targets for PTC and ATC with significant invasion or distant metastasis. Schematic summary of FTO-IGF2BP2 axis in modulation of CDH12 mRNA m6A and upregulation of CDH12 expression in the invasion and metastasis of thyroid carcinoma.

β-Cyclodextrin-Modified Laser-Induced Graphene Electrode for Detection of N6-Methyladenosine in RNA

Laser-induced graphene (LIG) possesses characteristics of easy handling, miniaturization, and unique electrical properties. We modified the surface of LIG by electropolymerizing β-cyclodextrin (β-CD), which was used to immobilize antibodies on the electrode surface for highly sensitive detection of targets. N6-methyladenosine (m6A) is the most prevalent reversible modification in mammalian messenger RNA and noncoding RNA, influencing the development of various cancers. Here, β-CD was electropolymerized to immobilize the anti-m6A antibody, which subsequently recognized the target m6A. This was integrated into the catalytic hydrogen peroxide-hydroquinone (H2O2-HQ) redox system using phos-tag-biotin to generate electrochemical signals from streptavidin-modified horseradish peroxidase (SA-HRP). Under optimal conditions, the biosensor exhibited a linear range from 0.1 to 100 nM with a minimum detection limit of 96 pM. The method was successfully applied to the recovery analysis of m6A from HeLa cells through spiking experiments and aims to inspire strategies for point-of-care testing (POCT).

Regulatory roles of N6-methyladenosine (m6A) methylation in RNA processing and non-communicable diseases

Post-transcriptional RNA modification is an emerging epigenetic control mechanism in cells that is important in many different cellular and organismal processes. N6-methyladenosine (m6A) is one of the most prevalent, prolific, and ubiquitous internal transcriptional alterations in eukaryotic mRNAs, making it an important topic in the field of Epigenetics. m6A methylation acts as a dynamical regulatory process that regulates the activity of genes and participates in multiple physiological processes, by supporting multiple aspects of essential mRNA metabolic processes, including pre-mRNA splicing, nuclear export, translation, miRNA synthesis, and stability. Extensive research has linked aberrations in m6A modification and m6A-associated proteins to a wide range of human diseases. However, the impact of m6A on mRNA metabolism and its pathological connection between m6A and other non-communicable diseases, including cardiovascular disease, neurodegenerative disorders, liver diseases, and cancer remains in fragmentation. Here, we review the existing understanding of the overall role of mechanisms by which m6A exerts its activities and address new discoveries that highlight m6A's diverse involvement in gene expression regulation. We discuss m6A deposition on mRNA and its consequences on degradation, translation, and transcription, as well as m6A methylation of non-coding chromosomal-associated RNA species. This study could give new information about the molecular process, early detection, tailored treatment, and predictive evaluation of human non-communicable diseases like cancer. We also explore more about new data that suggests targeting m6A regulators in diseases may have therapeutic advantages.

METTL3 promotes the osteogenic differentiation of human periodontal ligament cells by increasing YAP activity via IGF2BP1 and YTHDF1-mediated m6A modification

AIMS

N6-Methyladenosine (m6A) has been confirmed to play a dynamic role in osteoporosis and bone metabolism. However, whether m6A is involved in the osteogenic differentiation of human periodontal ligament cells (hPDLCs) remains unclear. The present study aimed to verify the role of methyltransferase-like 3 (METTL3)-mediated m6A modification in the osteogenic differentiation of hPDLCs.

METHODS

The METTL3, Runx2, Osx, and YAP mRNA expression was determined by qPCR. METTL3, RUNX2, OSX, YTHDF1, YAP, IGF2BP1, and eIF3a protein expression was measured by Western blotting and immunofluorescence assays. The levels of m6A modification were evaluated by methylated RNA immunoprecipitation (MeRIP) and dot blot analyses. MeRIP-seq and RNA-seq were used to screen potential candidate genes. Nucleic acid and protein interactions were detected by immunoprecipitation. Alizarin red staining was used to evaluate the osteogenic differentiation of hPDLCs. Gene transcription and promoter activities were assessed by luciferase reporter assays (n ≥ 3).

RESULTS

The expression of METTL3 and m6A modifications increased synchronously with the osteogenic differentiation of hPDLCs (p = .0016). YAP was a candidate gene identified by MeRIP-seq and RNA-seq, and its mRNA and protein expression levels were simultaneously increased. METTL3 increased the m6A methylated IGF2BP1-mediated stability of YAP mRNA (p = .0037), which in turn promoted osteogenic differentiation (p = .0147). Furthermore, METTL3 increased the translation efficiency of YAP by recruiting YTHDF1 and eIF3a to the translation initiation complex (p = .0154), thereby promoting the osteogenic differentiation of hPDLCs (p = .0012).

CONCLUSION

Our study revealed that METTL3-initiated m6A mRNA methylation promotes osteogenic differentiation of hPDLCs by increasing IGF2BP1-mediated YAP mRNA stability and recruiting YTHDF1 and eIF3a to the translation initiation complex to increase YAP mRNA translation. Our findings reveal the mechanism of METTL3-mediated m6A modification during hPDLC osteogenesis, providing a potential therapeutic target for periodontitis and alveolar bone defects.

Review of METTL3 in colorectal cancer: From mechanisms to the therapeutic potential

N6-methyladenosine (m6A), the most abundant modification in mRNAs, affects the fate of the modified RNAs at the post-transcriptional level and participants in various biological and pathological processes. Increasing evidence shows that m6A modification plays a role in the progression of many malignancies, including colorectal cancer (CRC). As the only catalytic subunit in methyltransferase complex, methyltransferase-like 3 (METTL3) is essential to the performance of m6A modification. It has been found that METTL3 is associated with the prognosis of CRC and significantly influences various aspects of CRC, such as cell proliferation, invasion, migration, metastasis, metabolism, tumor microcirculation, tumor microenvironment, and drug resistance. The relationship between METTL3 and gut-microbiota is also involved into the progression of CRC. Furthermore, METTL3 might be a viable target for CRC treatment to prolong survival. In this review, we comprehensively summarize the function of METTL3 in CRC and the underlying molecular mechanisms. We aim to deepen understanding and offer new ideas for diagnostic biomarkers and therapeutic targets for colorectal cancer.

The correlation between cancer stem cells and epithelial-mesenchymal transition: molecular mechanisms and significance in cancer theragnosis

The connections between cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) is critical in cancer initiation, progression, metastasis, and therapy resistance, making it a focal point in cancer theragnosis. This review provides a panorama of associations and regulation pathways between CSCs and EMT, highlighting their significance in cancer. The molecular mechanisms underlined EMT are thoroughly explored, including the involvement of key transcription factors and signaling pathways. In addition, the roles of CSCs and EMT in tumor biology and therapy resistance, is further examined in this review. The clinical implications of CSCs-EMT interplay are explored, including identifying mesenchymal-state CSC subpopulations using advanced research methods and developing targeted therapies such as inhibitors and combination treatments. Overall, understanding the reciprocal relationship between EMT and CSCs holds excellent potential for informing the development of personalized therapies and ultimately improving patient outcomes.

YTHDF3 modulates the progression of breast cancer cells by regulating FGF2 through m6A methylation

Introduction

Breast cancer (BC) is a prevailing malignancy among women, and its inconspicuous development contributes significantly to mortality. The RNA N6-methyladenosine (m6A) modification represents an emerging mechanism for gene expression regulation, with the active involvement of the YTH N6-methyladenosine RNA binding protein 3 (YTHDF3) in tumor progression across multiple cancer types. Nonetheless, its precise function in breast cancer necessitates further investigation.

Methods

The expression of YTHDF3 in both cell lines and patient tissues was examined using Western blotting, reverse transcription quantitative PCR (RT-qPCR), and immunohistochemistry (IHC) techniques. Bioinformatics analysis of methylated RNA immunoprecipitation sequencing (MeRIP-seq) and transcriptome RNA sequencing (RNA-seq) data was employed to screen for the target genes of YTHDF3. The main focus of this study was to investigate the in vitro biological functions of YTHDF3. The specific binding of YTHDF3 to its target genes and its correlation with m6A methylation were studied through RNA pull-down, RNA immunoprecipitation, and co-immunoprecipitation experiments. The protein regulatory mechanisms of downstream genes of YTHDF3 were assessed using protein stability analysis. Furthermore, the biological functions of YTHDF3 and its target genes in breast cancer cells were validated through CRISPR-Cas9 technology and rescue experiments.

Results

By constructing a risk model using the TCGA database, YTHDF3 was identified as a high-risk factor among m6A methylation factors. Subsequent investigations revealed its elevated expression in various subtypes of breast cancer, accompanied by poor prognosis. MeRIP-seq analysis further revealed fibroblast growth factor 2 (FGF2) as a downstream gene of YTHDF3. Knockdown of YTHDF3 in breast cancer cells led to significant inhibition of cell self-renewal, migration, and invasion abilities in vitro. Mechanistically, YTHDF3 specifically recognized the methylated transcript of FGF2 within its coding sequence (CDS) region, leading to the inhibition of FGF2 protein degradation. Moreover, depletion of FGF2 markedly suppressed the biological functions of breast cancer cells, while reducing FGF2 expression in YTHDF3-overexpressing breast cancer cell lines substantially alleviated the malignant progression.

Conclusions

In summary, our study elucidates the role of YTHDF3 as an oncogene in maintaining FGF2 expression in BC cells through an m6A-dependent mechanism. Additionally, we provide a potential biomarker panel for prognostic prediction in BC.

Targeting NAT10 inhibits osteosarcoma progression via ATF4/ASNS-mediated asparagine biosynthesis

Despite advances in treatment, the prognosis of patients with osteosarcoma remains unsatisfactory, and searching for potential targets is imperative. Here, we identify N4-acetylcytidine (ac4C) acetyltransferase 10 (NAT10) as a candidate therapeutic target in osteosarcoma through functional screening. NAT10 overexpression is correlated with a poor prognosis, and NAT10 knockout inhibits osteosarcoma progression. Mechanistically, NAT10 enhances mRNA stability of activating transcription factor 4 (ATF4) through ac4C modification. ATF4 induces the transcription of asparagine synthetase (ASNS), which catalyzes asparagine (Asn) biosynthesis, facilitating osteosarcoma progression. Utilizing virtual screening, we identify paliperidone and AG-401 as potential NAT10 inhibitors, and both inhibitors are found to bind to NAT10 proteins. Inhibiting NAT10 suppresses osteosarcoma progression in vivo. Combined treatment using paliperidone and AG-401 produces synergistic inhibition for osteosarcoma in patient-derived xenograft (PDX) models. Our findings demonstrate that NAT10 facilitates osteosarcoma progression through the ATF4/ASNS/Asn axis, and pharmacological inhibition of NAT10 may be a feasible therapeutic approach for osteosarcoma.

N6-methyladenosine triggers renal fibrosis via enhancing translation and stability of ZEB2 mRNA

In recent years, a surge in studies investigating N6-methyladenosine (m6A) modification in human diseases has occurred. However, the specific roles and mechanisms of m6A in kidney disease remain incompletely understood. This study revealed that m6A plays a positive role in regulating renal fibrosis (RF) by inducing epithelial-to-mesenchymal phenotypic transition (EMT) in renal tubular cells. Through comprehensive analyses, including m6A sequencing, RNA-seq, and functional studies, we confirmed the pivotal involvement of zinc finger E-box binding homeobox 2 (ZEB2) in m6A-mediated RF and EMT. Notably, the m6A-modified coding sequence of ZEB2 mRNA significantly enhances its translational elongation and mRNA stability by interacting with the YTHDF1/eEF-2 complex and IGF2BP3, respectively. Moreover, targeted demethylation of ZEB2 mRNA using the dm6ACRISPR system substantially decreases ZEB2 expression and disrupts the EMT process in renal tubular epithelial cells. In vivo and clinical data further support the positive influence of m6A/ZEB2 on RF progression. Our findings highlight the m6A-mediated regulation of RF through ZEB2, revealing a novel therapeutic target for RF treatment and enhancing our understanding of the impact of mRNA methylation on kidney disease.

Manipulating the tumour immune microenvironment by N6-methyladenosine RNA modification

N6-methyladenosine (m6A), a posttranscriptional regulatory mechanism, is the most common epigenetic modification in mammalian mRNA. M6A modifications play a crucial role in the developmental network of immune cells. The expression of m6A-related regulators often affects carcinogenesis and tumour suppression networks. In the tumour microenvironment, m6A-modified enzymes can affect the occurrence and progression of tumours by regulating the activation and invasion of tumour-associated immune cells. Immunotherapy, which utilises immune cells, has been demonstrated to be a powerful weapon in tumour treatment and is increasingly being used in the clinic. Here, we provide an updated and comprehensive overview of how m6A modifications affect invasive immune cells and their potential role in immune regulation. In addition, we summarise the regulation of epigenetic regulators associated with m6A modifications in tumour cells on the antitumour response of immune cells in the tumour immune microenvironment. These findings provide new insights into the role of m6A modifications in the immune response and tumour development, leading to the development of novel immunotherapies for cancer treatment.

METTL3-mediated upregulation of FAM135B promotes EMT of esophageal squamous cell carcinoma via regulating the Wnt/β-catenin pathway

Family with sequence similarity 135 member B (FAM135B) is a novel driver gene in esophageal squamous cell carcinoma (ESCC). However, little is known regarding its biological functions and mechanisms in ESCC. Here, we identified that the high expression of FAM135B was associated with lymph node metastasis and infiltrating development of ESCC. Elevated FAM135B expression promoted ESCC migration and invasion in vitro and lung metastasis in vivo. Furthermore, epithelial-mesenchymal transition (EMT)-related pathways were enriched in ESCC samples with high levels of FAM135B and FAM135B positively regulated EMT markers. Mechanistically, we observed that FAM135B interacted with the intermediate domain of TRAF2 and NCK-interacting kinase (TNIK), activating the Wnt/β-catenin signaling pathway. The facilitation of TNIK on ESCC migration and invasion was reversed by FAM135B siRNA. In addition, the N6-methyladenosine (m6A) modification positively regulated FAM135B expression, with methyltransferase like 3 (METTL3) acting as its substantial m6A writer. The pro-EMT effects of METTL3 overexpression were reversed by silencing FAM135B. Collectively, these findings illustrate the critical role of ABCDE in ESCC progression and provide new insights into the upstream and downstream mechanisms of FAM135B.NEW & NOTEWORTHY This study reveals for the first time that the novel cancer-related gene, FAM135B, promotes ESCC metastasis both in vitro and in vivo. Besides, we substantiate FAM135B's action on the β-catenin pathway through interacting with TNIK, thereby elucidating the promotional effect of FAM135B on ESCC EMT. Furthermore, we provide initial evidence demonstrating that METTL3-mediated m6A modification upregulates the expression of FAM135B in ESCC cells.

Insight into the regulatory mechanism of m6A modification: From MAFLD to hepatocellular carcinoma

In recent years, there has been a significant increase in the incidence of metabolic-associated fatty liver disease (MAFLD), which has been attributed to the increasing prevalence of type 2 diabetes mellitus (T2DM) and obesity. MAFLD affects more than one-third of adults worldwide, making it the most prevalent liver disease globally. Moreover, MAFLD is considered a significant risk factor for hepatocellular carcinoma (HCC), with MAFLD-related HCC cases increasing. Approximately 1 in 6 HCC patients are believed to have MAFLD, and nearly 40 % of these HCC patients do not progress to cirrhosis, indicating direct transformation from MAFLD to HCC. N6-methyladenosine (m6A) is commonly distributed in eukaryotic mRNA and plays a crucial role in normal development and disease progression, particularly in tumors. Numerous studies have highlighted the close association between abnormal m6A modification and cellular metabolic alterations, underscoring its importance in the onset and progression of MAFLD. However, the specific impact of m6A modification on the progression of MAFLD to HCC remains unclear. Can targeting m6A effectively halt the progression of MAFLD-related HCC? In this review, we investigated the pivotal role of abnormal m6A modification in the transition from MAFLD to HCC, explored the potential of m6A modification as a therapeutic target for MAFLD-related HCC, and proposed possible directions for future investigations.

Interaction of the intestinal cytokines-JAKs-STAT3 and 5 axes with RNA N6-methyladenosine to promote chronic inflammation-induced colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers, with a high mortality rate worldwide. Mounting evidence indicates that mRNA modifications are crucial in RNA metabolism, transcription, processing, splicing, degradation, and translation. Studies show that N6-methyladenosine (m6A) is mammalians' most common epi-transcriptomic modification. It has been demonstrated that m6A is involved in cancer formation, progression, invasion, and metastasis, suggesting it could be a potential biomarker for CRC diagnosis and developing therapeutics. Cytokines, growth factors, and hormones function in JAK/STAT3/5 signaling pathway, and they could regulate the intestinal response to infection, inflammation, and tumorigenesis. Reports show that the JAK/STAT3/5 pathway is involved in CRC development. However, the underlying mechanism is still unclear. Signal Transducer and Activator of Transcription 3/5 (STAT3, STAT5) can act as oncogenes or tumor suppressors in the context of tissue types. Also, epigenetic modifications and mutations could alter the balance between pro-oncogenic and tumor suppressor activities of the STAT3/5 signaling pathway. Thus, exploring the interaction of cytokines-JAKs-STAT3 and/or STAT5 with mRNA m6A is of great interest. This review provides a comprehensive overview of the characteristics and functions of m6A and JAKs-STAT3/5 and their relationship with gastrointestinal (GI) cancers.

miR-340-3p-modified bone marrow mesenchymal stem cell-derived exosomes inhibit ferroptosis through METTL3-mediated m6A modification of HMOX1 to promote recovery of injured rat uterus

BACKGROUND

Ferroptosis is associated with the pathological progression of hemorrhagic injury and ischemia-reperfusion injury. According to our previous study, exosomes formed through bone marrow mesenchymal stem cells modified with miR-340-3p (MB-exos) can restore damaged endometrium. However, the involvement of ferroptosis in endometrial injury and the effect of MB-exos on ferroptosis remain elusive.

METHODS

The endometrial injury rat model was developed. Exosomes were obtained from the supernatants of bone marrow mesenchymal stromal cells (BMSCs) and miR-340/BMSCs through differential centrifugation. We conducted RNA-seq analysis on endometrial tissues obtained from the PBS and MB-exos groups. Ferroptosis was induced in endometrial stromal cells (ESCs) by treating them with erastin or RSL3, followed by treatment with B-exos or MB-exos. We assessed the endometrial total m6A modification level after injury and subsequent treatment with B-exos or MB-exos by methylation quantification assay. We performed meRIP-qPCR to analyze m6A modification-regulated endogenous mRNAs.

RESULTS

We reveal that MB-exos facilitate the injured endometrium to recover by suppressing ferroptosis in endometrial stromal cells. The injured endometrium showed significantly upregulated N6-methyladenosine (m6A) modification levels; these levels were attenuated by MB-exos through downregulation of the methylase METTL3. Intriguingly, METTL3 downregulation appears to repress ferroptosis by stabilizing HMOX1 mRNA, thereby potentially elucidating the mechanism through which MB-exos inhibit ferroptosis in ESCs. We identified YTHDF2 as a critical m6A reader protein that contributes to HMOX1 mRNA degradation. YTHDF2 facilitates HMOX1 mRNA degradation by identifying the m6A binding site in the 3'-untranslated regions of HMOX1. In a rat model, treatment with MB-exos ameliorated endometrial injury-induced fibrosis by inhibiting ferroptosis in ESCs. Moreover, METTL3 short hairpin RNA-mediated inhibition of m6A modification enhanced the inhibitory effect of MB-exos on ferroptosis in endometrial injury.

CONCLUSIONS

Thus, these observations provide new insights regarding the molecular mechanisms responsible for endometrial recovery promotion by MB-exos and highlight m6A modification-dependent ferroptosis inhibition as a prospective therapeutic target to attenuate endometrial injury.

N6-Methyladenosine enhances the translation of ENO1 to promote the progression of bladder cancer by inhibiting PCNA ubiquitination

The mechanism underlying N6-methyladenosine (m6A) modification in bladder cancer (BC) remains elusive. We identified that the RBM15/METTL3 complex enhances m6A modification and promotes the ENO1 protein translation efficiency through its 359A site by depending on YTHDF1 in BC cells. In the tumor microenvironment, TGF-β effectively stimulates RBM15/METTL3 expression to improve ENO1 mRNA m6A modification through the Smad2/3 pathway. Reduced ENO1 m6A levels hamper tumor proliferation both in vitro and in vivo. Mechanistically, ENO1 augments PCNA protein stability by reducing its K48-linked ubiquitination and thus prevents protein degradation through the endoplasmic reticulum-associated degradation pathway. According to the subsequent experiments, the ENO1 inhibitor significantly reduced tumor proliferation both in vitro and in vivo. Our study highlights the significance of RBM15/METTL3 complex-mediated ENO1 mRNA m6A modification in ENO1 expression. It also reveals a novel mechanism by which ENO1 promotes BC progression, thereby suggesting that ENO1 can be a therapeutic target for BC.

METTL14 promotes lipid metabolism reprogramming and sustains nasopharyngeal carcinoma progression via enhancing m6A modification of ANKRD22 mRNA

BACKGROUND

N6-methyladenosine (m6A) modification is essential for modulating RNA processing as well as expression, particularly in the context of malignant tumour progression. However, the exploration of m6A modification in nasopharyngeal carcinoma (NPC) remains very limited.

METHODS

RNA m6A levels were analysed in NPC using m6A dot blot assay. The expression level of methyltransferase-like 14 (METTL14) within NPC tissues was analysed from public databases as well as RT-qPCR and immunohistochemistry. The influences on METTL14 expression on NPC proliferation and metastasis were explored via in vitro as well as in vivo functional assays. Targeted genes of METTL14 were screened using the m6A and gene expression profiling microarray data. Actinomycin D treatment and polysome analysis were used to detect the half-life and translational efficiency of ANKRD22. Flow cytometry, immunofluorescence and immunoprecipitation were used to validate the role of ANKRD22 on lipid metabolism in NPC cells. ChIP-qPCR analysis of H3K27AC signalling near the promoters of METTL14, GINS3, POLE2, PLEK2 and FERMT1 genes.

RESULTS

We revealed METTL14, in NPC, correlating with poor patient prognosis. In vitro and in vivo assays indicated METTL14 actively promoted NPC cells proliferation and metastasis. METTL14 catalysed m6A modification on ANKRD22 messenger ribonucleic acid (mRNA), recognized by the reader IGF2BP2, leading to increased mRNA stability and higher translational efficiency. Moreover, ANKRD22, a metabolism-related protein on mitochondria, interacted with SLC25A1 to enhance citrate transport, elevating intracellular acetyl-CoA content. This dual impact of ANKRD22 promoted lipid metabolism reprogramming and cellular lipid synthesis while upregulating the expression of genes associated with the cell cycle (GINS3 and POLE2) and the cytoskeleton (PLEK2 and FERMT1) through heightened epigenetic histone acetylation levels in the nucleus. Intriguingly, our findings highlighted elevated ANKRD22-mediated histone H3 lysine 27 acetylation (H3K27AC) signals near the METTL14 promoter, which contributes to a positive feedback loop perpetuating malignant progression in NPC.

CONCLUSIONS

The identified METTL14-ANKRD22-SLC25A1 axis emerges as a promising therapeutic target for NPC, and also these molecules may serve as novel diagnostic biomarkers.

m6A mRNA methylation-mediated MAPK signaling modulates the nasal mucosa inflammatory response in allergic rhinitis

Background

Allergic rhinitis (AR) is a complex disease in which gene-environment interactions contribute to its pathogenesis. Epigenetic modifications, such as N6-methyladenosine (m6A) modification of mRNA, play important roles in regulating gene expression in multiple physiological and pathological processes. However, the function of m6A modification in AR and the inflammatory response is poorly understood.

Methods

We used the ovalbumin (OVA) and aluminum hydroxide to induce an AR mouse model. Nasal symptoms, histopathology, and serum cytokines were examined. We performed combined m6A and RNA sequencing to analyze changes in m6A modification profiles. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and methylated RNA immunoprecipitation sequencing qPCR (MeRIP-qPCR) were used to verify differential methylation of mRNAs and the m6A methylation level. Knockdown or inhibition of Alkbh5 in nasal mucosa of mice was mediated by lentiviral infection or IOX1 treatment.

Results

We showed that m6A was enriched in a group of genes involved in MAPK signaling pathway. Moreover, we identified a MAPK pathway involving Map3k8, Erk2, and Nfκb1 that may play a role in the disrupted inflammatory response associated with nasal inflammation. The m6A eraser, Alkbh5, was highly expressed in the nasal mucosa of AR model mice. Furthermore, knockdown of Alkbh5 expression by lentiviral infection resulted in high MAPK pathway activity and a significant nasal mucosa inflammatory response. Our findings indicate that ALKBH5-mediated m6A dysregulation likely contributes to a nasal inflammatory response via the MAPK pathway.

Conclusion

Together, our data show that m6A dysregulation mediated by ALKBH5, is likely to contribute to inflammation of the nasal mucosa via the MAPK signaling pathway, suggesting that ALKBH5 is a potential biomarker for AR treatment.

m6A Modification Promotes EMT and Metastasis of Castration-Resistant Prostate Cancer by Upregulating NFIB

The widespread use of androgen receptor (AR) signaling inhibitors has led to an increased incidence of AR-negative castration-resistant prostate cancer (CRPC), limiting effective treatment and patient survival. A more comprehensive understanding of the molecular mechanisms supporting AR-negative CRPC could reveal therapeutic vulnerabilities to improve treatment. This study showed that the transcription factor nuclear factor I/B (NFIB) was upregulated in patient with AR-negative CRPC tumors and cell lines and was positively associated with an epithelial-to-mesenchymal transition (EMT) phenotype. Loss of NFIB inhibited EMT and reduced migration of CRPC cells. NFIB directly bound to gene promoters and regulated the transcription of EMT-related factors E-cadherin (CDH1) and vimentin (VIM), independent of other typical EMT-related transcriptional factors. In vivo data further supported the positive role of NFIB in the metastasis of AR-negative CRPC cells. Moreover, N6-methyladenosine (m6A) modification induced NFIB upregulation in AR-negative CRPC. Mechanistically, the m6A levels of mRNA, including NFIB and its E3 ubiquitin ligase TRIM8, were increased in AR-negative CRPC cells. Elevated m6A methylation of NFIB mRNA recruited YTHDF2 to increase mRNA stability and protein expression. Inversely, the m6A modification of TRIM8 mRNA, induced by ALKBH5 downregulation, decreased its translation and expression, which further promoted NFIB protein stability. Overall, this study reveals that upregulation of NFIB, mediated by m6A modification, triggers EMT and metastasis in AR-negative CRPC. Targeting the m6A/NFIB axis is a potential prevention and treatment strategy for AR-negative CRPC metastasis.

SIGNIFICANCE

NFIB upregulation mediated by increased m6A levels in AR-negative castration-resistant prostate cancer regulates transcription of EMT-related factors to promote metastasis, providing a potential therapeutic target to improve prostate cancer treatment.

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

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

Glycolysis and tumor progression promoted by the m6A writer VIRMA via m6A-dependent upregulation of STRA6 in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal malignancies, highlighting the urgent need to elucidate the underlying oncogenic mechanisms. VIRMA is a classic isoform of methyltransferases that participates in epigenetic transcriptomic modification in eukaryotic mRNAs. However, the exact roles of VIRMA in PDAC remain unclear. Here, we identified that VIRMA is highly expressed in PDAC, and histone modifications of the promoter may partly account for this dysregulation. Moreover, VIRMA is closely related to glycolysis and poor prognosis in PDAC. We further determined that STRA6 is a direct downstream target of VIRMA in PDAC by RNA sequencing (RNA-seq) and m6A sequencing (m6A-seq). VIRMA is involved in gene expression regulation via 3' UTR targeting of STRA6 mRNA. Furthermore, the m6A reader IGF2BP2 was shown to critically contribute to the stability of STRA6 mRNA. We describe the role of VIRMA in promoting signaling via the STRA6/STAT3 axis, which results in increased levels of HIF-1α, a key activator of glycolysis. In vivo and in vitro experiments reveal that the VIRMA-STRA6-STAT3-HIF-1α axis plays an instrumental role in glycolysis and tumor progression in PDAC. In conclusion, we demonstrate that VIRMA can increase glycolysis in PDAC by upregulating STRA6, a cell surface membrane protein that stimulates the STAT3 pathway, thereby activating HIF-1α and leading to pancreatic cancer malignancy. Overall, our data strongly suggest that the VIRMA-STRA6-STAT3-HIF-1α axis is a viable therapeutic target in PDAC.

RNA m6A methylation and regulatory proteins in pulmonary arterial hypertension

m6A (N6‑methyladenosine) is the most common and abundant apparent modification in mRNA of eukaryotes. The modification of m6A is regulated dynamically and reversibly by methyltransferase (writer), demethylase (eraser), and binding protein (reader). It plays a significant role in various processes of mRNA metabolism, including regulation of transcription, maturation, translation, degradation, and stability. Pulmonary arterial hypertension (PAH) is a malignant cardiopulmonary vascular disease characterized by abnormal proliferation of pulmonary artery smooth muscle cells. Despite the existence of several effective and targeted therapies, there is currently no cure for PAH and the prognosis remains poor. Recent studies have highlighted the crucial role of m6A modification in cardiovascular diseases. Investigating the role of RNA m6A methylation in PAH could provide valuable insights for drug development. This review aims to explore the mechanism and function of m6A in the pathogenesis of PAH and discuss the potential targeting of RNA m6A methylation modification as a treatment for PAH.

Comprehensive analysis of m6A modification in immune infiltration, metabolism and drug resistance in hepatocellular carcinoma

N6-methyladenosine (m6A) is important in regulating mRNA stability, splicing, and translation, and it also contributes to tumor development. However, there is still limited understanding of the comprehensive effects of m6A modification patterns on the tumor immune microenvironment, metabolism, and drug resistance in hepatocellular carcinoma (HCC). In this study, we utilized unsupervised clustering based on the expression of 23 m6A regulators to identify m6A clusters. We identified differential m6A modification patterns and characterized m6A-gene-cluster A, which exhibited poorer survival rates, a higher abundance of Treg cells, and increased expression of TGFβ in the tumor microenvironment (TME). Additionally, m6A-gene-cluster A demonstrated higher levels of glycolysis activity, cholesterol metabolism, and fatty acid biosynthesis. We also found that the m6A score was associated with prognosis and drug resistance. Patients with a low m6A score experienced worse prognoses, which were linked to an abundance of Treg cells, upregulation of TGFβ, and increased metabolic activity. HCC patients with a higher m6A score showed improved prognosis following sorafenib treatment and immunotherapy. In conclusion, we reveals the association between m6A modification patterns and the tumor immune microenvironment, metabolism, and drug resistance in HCC. Furthermore, the m6A score holds potential as a predictive factor for the efficacy of targeted therapy and immunotherapy in HCC.

METTL3 recruiting M2-type immunosuppressed macrophages by targeting m6A-SNAIL-CXCL2 axis to promote colorectal cancer pulmonary metastasis

BACKGROUND

The regulatory role of N6-methyladenosine (m6A) modification in the onset and progression of cancer has garnered increasing attention in recent years. However, the specific role of m6A modification in pulmonary metastasis of colorectal cancer remains unclear.

METHODS

This study identified differential m6A gene expression between  primary colorectal cancer and its pulmonary metastases using transcriptome sequencing and immunohistochemistry. We investigated the biological function of METTL3 gene both in vitro and in vivo using assays such as CCK-8, colony formation, wound healing, EDU, transwell, and apoptosis, along with a BALB/c nude mouse model. The regulatory mechanisms of METTL3 in colorectal cancer pulmonary metastasis were studied using methods like methylated RNA immunoprecipitation quantitative reverse transcription PCR, RNA stability analysis, luciferase reporter gene assay, Enzyme-Linked Immunosorbent Assay, and quantitative reverse transcription PCR.

RESULTS

The study revealed high expression of METTL3 and YTHDF1 in the tumors of patients with pulmonary metastasis of colorectal cancer. METTL3 promotes epithelial-mesenchymal transition in colorectal cancer by m6A modification of SNAIL mRNA, where SNAIL enhances the secretion of CXCL2 through the NF-κB pathway. Additionally, colorectal cancer cells expressing METTL3 recruit M2-type macrophages by secreting CXCL2.

CONCLUSION

METTL3 facilitates pulmonary metastasis of colorectal cancer by targeting the m6A-Snail-CXCL2 axis to recruit M2-type immunosuppressive macrophages. This finding offers new research directions and potential therapeutic targets for colorectal cancer treatment.

Manganese induces oxidative damage in the hippocampus by regulating the expression of oxidative stress-related genes via modulation of H3K18 acetylation

Prolonged exposure to manganese (Mn) contributes to hippocampal Mn accumulation, which leads to neurodegenerative diseases called manganese poisoning. However, the underlying molecular mechanisms remain unclear and there are no ideal biomarkers. Oxidative stress is the essential mechanisms of Mn-related neurotoxicity. Furthermore, histone acetylation has been identified as being engaged in the onset and development of neurodegenerative diseases. Therefore, the work aims to understand the molecular mechanisms of oxidative damage in the hippocampus due to Mn exposure from the aspect of histone acetylation modification and to assess whether H3K18 acetylation (H3K18ac) modification level in peripheral blood reflect Mn-induced oxidative damage in the hippocampus. Here, we randomly divided 60 male rats into four groups and injected them intraperitoneally with sterile pure water and MnCl2 ⋅4H2 O (5, 10, and 15 mg/kg) for 16 weeks, 5 days a week, once a day. The data confirmed that Mn exposure down-regulated superoxide dismutase activity and glutathione level as well as up-regulated malondialdehyde level in the hippocampus and plasma, and that there was a positive correlation between these indicators in the hippocampus and plasma. Besides, we noted that Mn treatment upregulated H3K18ac modification levels in the hippocampus and peripheral blood and that H3K18ac modification levels correlated with oxidative stress. Further studies demonstrated that Mn treatment decreased the amounts of H3K18ac enrichment in the manganese superoxide dismutase (SOD2) and glutathione transferase omega 1 (GSTO1) gene promoter regions, contributing to oxidative damage in the hippocampus. In short, our results demonstrate that Mn induces oxidative damage in the hippocampus by inhibiting the expression of SOD2 and GSTO1 genes via modulation of H3K18ac. In assessing Mn-induced hippocampal neurotoxicity, oxidative damage in plasma may reflect hippocampal oxidative damage in Mn-exposed groups.

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

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

N6-methyladenosine (m6A) modification in hepatocellular carcinoma

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

Desulfovibrio desulfuricans and its derived metabolites confer resistance to FOLFOX through METTL3

BACKGROUND

Chemoresistance is a critical factor contributing to poor prognosis in clinical patients with cancer undergoing postoperative adjuvant chemotherapy. The role of gut microbiota in mediating resistance to tumour chemotherapy remains to be investigated.

METHODS

Patients with CRC were categorised into clinical benefit responders (CBR) and no clinical benefit responders (NCB) based on chemotherapy efficacy. Differential bacterial analysis using 16S rRNA sequencing revealed Desulfovibrio as a distinct microbe between the two groups. Employing a syngeneic transplantation model, we assessed the effect of Desulfovibrio on chemotherapy by measuring tumour burden, weight, and Ki-67 expression. We further explored the mechanisms underlying the compromised chemotherapeutic efficacy of Desulfovibrio using metabolomics, western blotting, colony formation, and cell apoptosis assays.

FINDINGS

In comparison, Desulfovibrio was more abundant in the NCB group. In vivo experiments revealed that Desulfovibrio colonisation in the gut weakened the efficacy of FOLFOX. Treatment with Desulfovibrio desulfuricans elevates serum S-adenosylmethionine (SAM) levels. Interestingly, SAM reduced the sensitivity of CRC cells to FOLFOX, thereby promoting the growth of CRC tumours. These experiments suggest that SAM promotes the growth and metastasis of CRC by driving the expression of methyltransferase-like 3 (METTL3).

INTERPRETATION

A high abundance of Desulfovibrio in the intestines indicates poor therapeutic outcomes for postoperative neoadjuvant FOLFOX chemotherapy in CRC. Desulfovibrio drives the manifestation of METTL3 in CRC, promoting resistance to FOLFOX chemotherapy by increasing the concentration of SAM.

FUNDING

This study is supported by Wuxi City Social Development Science and Technology Demonstration Project (N20201005).

Epigenetic regulation of TGF-β pathway and its role in radiation response

PURPOSE

Transforming growth factor (TGF-β) plays a dual role in tumor progression as well as a pivotal role in radiation response. TGF-β-related epigenetic regulations, including DNA methylation, histone modifications (including methylation, acetylation, phosphorylation, ubiquitination), chromatin remodeling and non-coding RNA regulation, have been found to affect the occurrence and development of tumors as well as their radiation response in multiple dimensions. Due to the significance of radiotherapy in tumor treatment and the essential roles of TGF-β signaling in radiation response, it is important to better understand the role of epigenetic regulation mechanisms mediated by TGF-β signaling pathways in radiation-induced targeted and non-targeted effects.

CONCLUSIONS

By revealing the epigenetic mechanism related to TGF-β-mediated radiation response, summarizing the existing relevant adjuvant strategies for radiotherapy based on TGF-β signaling, and discovering potential therapeutic targets, we hope to provide a new perspective for improving clinical treatment.

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

BACKGROUND

As the most abundant modification in eukaryotic messenger RNAs (mRNAs), N6-methyladenosine (m6A) plays vital roles in many biological processes.

METHODS

Methylated 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.

RESULTS

We 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.

FTO-mediated autophagy inhibition promotes non-small cell lung cancer progression by reducing the stability of SESN2 mRNA

The role of fat mass and obesity-associated protein (FTO), an N6-methyladenosine (m6A) demethylase, in non-small cell lung cancer (NSCLC) has recently received widespread attention. However the underlying mechanisms of FTO-mediated autophagy regulation in NSCLC progression remain elusive. In this study, we found that FTO was significantly upregulated in NSCLC, and downregulation of FTO suppressed the growth, invasion and migration of NSCLC cells by inducing autophagy. FTO knockdown resulted in elevated m6A levels in NSCLC cells. Methylated RNA immunoprecipitation sequencing showed that sestrin 2 (SESN2) was involved in m6A regulation during autophagy in NSCLC cells. Interestingly, m6A modifications in exon 9 of SESN2 regulated its stability. FTO deficiency promoted the binding of insulin-like growth factor 2 mRNA-binding protein 1 to SESN2 mRNA, enhancing its stability and elevating its protein expression. FTO inhibited autophagic flux by downregulating SESN2, thereby promoting the growth, invasion and migration of NSCLC cells. Besides, the mechanism by which FTO blocked SESN2-mediated autophagy activation was associated with the AMPK-mTOR signaling pathway. Taken together, these findings uncover an essential role of the FTO-autophagy-SESN2 axis in NSCLC progression.

METTL3 promotes cellular senescence of colorectal cancer via modulation of CDKN2B transcription and mRNA stability

Cellular senescence plays a critical role in cancer development, but the underlying mechanisms remain poorly understood. Our recent study uncovered that replicative senescent colorectal cancer (CRC) cells exhibit increased levels of mRNA N6-methyladenosine (m6A) and methyltransferase METTL3. Knockdown of METTL3 can restore the senescence-associated secretory phenotype (SASP) of CRC cells. Our findings, which were confirmed by m6A-sequencing and functional studies, demonstrate that the cyclin-dependent kinase inhibitor 2B (CDKN2B, encoding p15INK4B) is a mediator of METTL3-regulated CRC senescence. Specifically, m6A modification at position A413 in the coding sequence (CDS) of CDKN2B positively regulates its mRNA stability by recruiting IGF2BP3 and preventing binding with the CCR4-NOT complex. Moreover, increased METTL3 methylates and stabilizes the mRNA of E2F1, which binds to the -208 to -198 regions of the CDKN2B promoter to facilitate transcription. Inhibition of METTL3 or specifically targeting CDKN2B methylation can suppress CRC senescence. Finally, the METTL3/CDKN2B axis-induced senescence can facilitate M2 macrophage polarization and is correlated with aging and CRC progression. The involvement of METTL3/CDKN2B in cell senescence provides a new potential therapeutic target for CRC treatment and expands our understanding of mRNA methylation's role in cellular senescence.

Decoding m6A mRNA methylation by reader proteins in liver diseases

N6-methyladenosine (m6A) is a dynamic and reversible epigenetic regulation. As the most prevalent internal post-transcriptional modification in eukaryotic RNA, it participates in the regulation of gene expression through various mechanisms, such as mRNA splicing, nuclear export, localization, translation efficiency, mRNA stability, and structural transformation. The involvement of m6A in the regulation of gene expression depends on the specific recognition of m6A-modified RNA by reader proteins. In the pathogenesis and treatment of liver disease, studies have found that the expression levels of key genes that promote or inhibit the development of liver disease are regulated by m6A modification, in which abnormal expression of reader proteins determines the fate of these gene transcripts. In this review, we introduce m6A readers, summarize the recognition and regulatory mechanisms of m6A readers on mRNA, and focus on the biological functions and mechanisms of m6A readers in liver cancer, viral hepatitis, non-alcoholic fatty liver disease (NAFLD), hepatic fibrosis (HF), acute liver injury (ALI), and other liver diseases. This information is expected to be of high value to researchers deciphering the links between m6A readers and human liver diseases.

Phenethyl isothiocyanate inhibits metastasis potential of non-small cell lung cancer cells through FTO mediated TLE1 m6A modification

N6-methyladenosine (m6A) modification is a prevalent RNA epigenetic modification, which plays a crucial role in tumor progression including metastasis. Isothiocyanates (ITCs) are natural compounds and inhibit the tumorigenesis of various cancers. Our previous studies show that ITCs inhibit the proliferation and metastasis of non-small cell lung cancer (NSCLC) cells, and have synergistic effects with chemotherapy drugs. In this study, we investigated the molecular mechanisms underlying the inhibitory effects of ITCs on cancer cell metastasis. We showed that phenethyl isothiocyanate (PEITC) dose-dependently inhibited the cell viability of both NSCLC cell lines H1299 and H226 with IC50 values of 17.6 and 15.2 μM, respectively. Furthermore, PEITC dose-dependently inhibited the invasion and migration of H1299 and H226 cells. We demonstrated that PEITC treatment dose-dependently increased m6A methylation levels and inhibited the expression of the m6A demethylase fat mass and obesity-associated protein (FTO) in H1299 and H226 cells. Knockdown of FTO significantly increased m6A methylation in H1299 and H226 cells, impaired their abilities of invasion and migration in vitro, and enhanced the inhibition of PEITC on tumor growth in vivo. Overexpression of FTO promoted the migration of NSCLC cells, and also mitigated the inhibitory effect of PEITC on migration of NSCLC cells. Furthermore, we found that FTO regulated the mRNA m6A modification of a transcriptional co-repressor Transducin-Like Enhancer of split-1 (TLE1) and further affected its stability and expression. TCGA database analysis revealed TLE1 was upregulated in NSCLC tissues compared to normal tissues, which might be correlated with the metastasis status. Moreover, we showed that PEITC suppressed the migration of NSCLC cells by inhibiting TLE1 expression and downstream Akt/NF-κB pathway. This study reveals a novel mechanism underlying ITC's inhibitory effect on metastasis of lung cancer cells, and provided valuable information for developing new therapeutics for lung cancer by targeting m6A methylation.

METTL4 mediated-N6-methyladenosine promotes acute lung injury by activating ferroptosis in alveolar epithelial cells

Sepsis-induced acute lung injury has been deemed to be an life-threatening pulmonary dysfunction caused by a dysregulated host response to infection. The modification of N6-Methyladenosine (m6A) is implicated in several biological processes, including mitochondrial transcription and ferroptosis. Ferroptosis is an iron-dependent type of programed cell death, which plays a role in sepsis-induced acute lung injury (ALI). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial regulator of intracellular oxidative homeostasis, linked to ferroptosis resistance. This research aims to explore the effect of m6A in ferroptosis in sepsis-induced ALI. First, we found a time-dependent dynamic alteration on pulmonary methylation level during sepsis-induced ALI. We identified METTL4 as a differentially expressed gene in ALI mice using m6A sequencing and RNA-sequencing, and revealed the methylation of several ferroptosis related genes (Nrf2). Thus, we generated METTL4 deficiency mice and found that METTL4 knockdown alleviated ferroptosis, as evidenced by lipid ROS, MDA, Fe2+, as well as alterations in GPX4 and SLC7A11 protein expression. Consistently, we found that METTL4 silencing could decrease ferroptosis sensitivity in LPS-induced TC-1 cells. Furthermore, both the dual-luciferase reporter assay and rescue experiments indicated that METTL4 mediated the N6-methyladenosine of Nrf2 3'UTR, then YTHDF2 binded with the m6A site, promoting the degradation of Nrf2. In conclusion, we revealed that METTL4 promoted alveolar epithelial cells ferroptosis in sepsis-induced lung injury via N6-methyladenosine of Nrf2, which might provide a novel approach to therapeutic strategies for sepsis-induced ALI.

Diagnostic and therapeutic potentials of methyltransferase-like 3 in liver diseases

Methyltransferase-like 3 (METTL3), a component of the RNA N6-methyladenosine (m6A) modification with a specific catalytic capacity, controls gene expression by actively regulating RNA splicing, nuclear export, stability, and translation, determines the fate of RNAs and assists in regulating biological processes. Studies conducted in recent decades have demonstrated the pivotal regulatory role of METTL3 in liver disorders, including hepatic lipid metabolism disorders, liver fibrosis, nonalcoholic steatohepatitis, and liver cancer. Although METTL3's roles in these diseases have been extensively investigated, the regulatory network of METTL3 and its potential applications remain unexplored. In this review, we provide a comprehensive overview of the roles and mechanisms of METTL3 implicated in these diseases, establish a regulatory network of METTL3, evaluate the potential for targeting METTL3 for diagnosis and treatment, and discuss avenues for future development and research. We found relatively upregulated expressions of METTL3 in these liver diseases, demonstrating its potential as a diagnostic biomarker and therapeutic target.

The FTO Mediated N6-Methyladenosine Modification of DDIT4 Regulation with Tumorigenesis and Metastasis in Prostate Cancer

The progression of numerous malignancies has been linked to N6-methyladenosine (m6A) alteration. However, the opposite trend of m6A levels in the development and metastasis of cancer has not been reported. This study aimed to evaluate the biological function and mechanism of fat mass and obesity-associated protein (FTO) in regulating m6A modification in prostate cancer development and epithelial-mesenchymal transition (EMT). An EMT model of LNCaP and PC-3 cells was established with transforming growth factor-β treatment, and FTO knockout cell line was established in prostate cancer cells using the CRISPR/Cas9 gene editing technology. The level of m6A modification in tumor tissues was higher than that in normal prostate tissues; m6A levels were decreased after EMT. FTO deletion increased m6A expression and enhanced PC-3 cell motility, invasion, and EMT both in vitro and in vivo. RNA sequencing and functional investigations suggested that DDIT4, a novel EMT target gene, plays a role in m6A-regulated EMT, which was recognized and stabilized by the m6A effector IGF2BP2/3. Decreased FTO expression was an independent indicator of worse survival, and the level of DDIT4 was considerably elevated in patients with bone metastasis. Thus, this study revealed that the m6A demethylase FTO can play different roles in prostate cancer as a regulator of EMT and an inhibitor of m6A modification. Moreover, DDIT4 can be suggested as a possible biomarker for prostate cancer metastasis prediction.

PSME2 offers value as a biomarker of M1 macrophage infiltration in pan-cancer and inhibits osteosarcoma malignant phenotypes

A growing number of studies have revealed an association between proteasome activator complex subunit 2 (PSME2) and the progression of various forms of cancer. However, the effect of PSME2 on osteosarcoma progression is unknown. Pan-cancer analyses focused on the immunological activity and prognostic relevance of PSME2 have yet to be conducted. The Cancer Genome Atlas and Genome-Tissue Expression databases were leveraged to evaluate PSME2 expression and activity across 33 cancer types. Significant PSME2 dysregulation was noted in a wide range of cancer types and this gene was found to offer significant diagnostic and prognostic utility in most analyzed cancers. From a mechanistic perspective, PSME2 expression levels were correlated with DNA methylation, DNA repair, genomic instability, and TME scores in multiple cancer types. PSME2 was subsequently established as a pan-cancer biomarker of M1 macrophage infiltration based on a combination of bulk, single-cell, and spatial transcriptomic data and confirmatory fluorescent staining results. In osteosarcoma cells, overexpressing PSME2 significantly suppressed tumor proliferative, migratory, and invasive activity. Screening efforts also successfully identified the PSME2-activating drug irinotecan, which can synergistically promote the death of osteosarcoma cells when combined with the chemotherapeutic drug paclitaxel. As a biomarker of M1 macrophage infiltration, PSME2 expression levels may offer insight into tumor development and progression for a wide range of cancers including osteosarcoma, emphasizing its potential utility as a prognostic and therapeutic target worthy of further study.

HIF-1α/m6A/NF-κB/CCL3 axis-mediated immunosurveillance participates in low level benzene-related erythrohematopoietic development toxicity

Defective erythropoiesis is one of the causes of anemia and leukemia. However, the mechanisms underlying defective erythropoiesis under a low-dose environment of benzene are poorly understood. In the present study, multiple omics (transcriptomics and metabolomics) and methods from epidemiology to experimental biology (e.g., benzene-induced (WT and HIF-1α + ) mouse, hiPSC-derived HSPCs) were used. Here, we showed that erythropoiesis is more easily impacted than other blood cells, and the process is reversible, which involves HIF-1 and NF-kB signaling pathways in low-level benzene exposure workers. Decreased HIF-1α expression in benzene-induced mouse bone marrow resulted in DNA damage, senescence, and apoptosis in BMCs and HSCs, causing disturbances in iron homeostasis and erythropoiesis. We further revealed that HIF-1α mediates CCL3/macrophage-related immunosurveillance against benzene-induced senescent and damaged cells and contributes to iron homeostasis. Mechanistically, we showed that m6A modification is essential in this process. Benzene-induced depletion of m6A promotes the mRNA stability of gene NFKBIA and regulates the NF-κB/CCL3 pathway, which is regulated by HIF-1α/METTL3/YTHDF2. Overall, our results identified an unidentified role for HIF-1α, m6A, and the NF-kB signaling machinery in erythroid progenitor cells, suggesting that HIF-1α/METTL3/YTHDF2-m6A/NF-κB/CCL3 axis may be a potential prevention and therapeutic target for chronic exposure of humans to benzene-associated anemia and leukemia.

Epigenetic regulation of mRNA mediates the phenotypic plasticity of cancer cells during metastasis and therapeutic resistance (Review)

Plasticity, the ability of cancer cells to transition between differentiation states without genomic alterations, has been recognized as a major source of intratumoral heterogeneity. It has a crucial role in cancer metastasis and treatment resistance. Thus, targeting plasticity holds tremendous promise. However, the molecular mechanisms of plasticity in cancer cells remain poorly understood. Several studies found that mRNA, which acts as a bridge linking the genetic information of DNA and protein, has an important role in translating genotypes into phenotypes. The present review provided an overview of the regulation of cancer cell plasticity occurring via changes in the transcription and editing of mRNAs. The role of the transcriptional regulation of mRNA in cancer cell plasticity was discussed, including DNA‑binding transcriptional factors, DNA methylation, histone modifications and enhancers. Furthermore, the role of mRNA editing in cancer cell plasticity was debated, including mRNA splicing and mRNA modification. In addition, the role of non‑coding (nc)RNAs in cancer plasticity was expounded, including microRNAs, long intergenic ncRNAs and circular RNAs. Finally, different strategies for targeting cancer cell plasticity to overcome metastasis and therapeutic resistance in cancer were discussed.