Recent advances in crosstalk between N6-methyladenosine (m6A) modification and circular RNAs in cancer

Stroke triggers dynamic m6A reprogramming of cerebral circular RNAs

We previously showed that stroke alters circular RNA (circRNA) expression profiles. Many circRNAs undergo epitranscriptomic modifications, particularly methylation of adenosine to form N6-methyladenosine (m6A). This modification significantly influences the circRNA metabolism and functionality. Hence, we currently evaluated if transient focal ischemia in adult C57BL/6J mice alters the m6A methylation of circRNAs. Changes in m6A were profiled in the peri-infarct cortex following immunoprecipitation coupled with microarrays. Correlation and gene ontology analyses were performed to understand the association of m6A changes with circRNA regulation and functional implications after stroke. Many circRNAs showed differential regulation (up or down) after stroke, and this change was highest at 24h of reperfusion. Notably, most circRNAs differentially regulated after stroke also exhibited temporal changes in m6A modification patterns. The majority of circRNAs that showed post-stroke differential m6A modifications were derived from protein-coding genes. Hyper-than hypomethylation of circRNAs was most prevalent after stroke. Gene ontology analysis of the host genes suggested that m6A-modified circRNAs might regulate functions such as synapse-related processes, indicating that m6A epitranscriptomic modification in circRNAs could potentially influence post-stroke synaptic pathophysiology.

Cross-talk between circRNAs and m6A modifications in solid tumors

Circular RNAs (circRNAs) possess unique biological properties and distribution characteristics that enable a variety of biological functions. N6-methyladenosine (m6A), a prevalent epigenetic modification in organisms, is regulated by factors including methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers). These factors play critical roles in various pathophysiological processes. There is growing evidence that m6A modifications are common within circRNAs, affecting their synthesis, translation, translocation, degradation, and stability. Additionally, circRNAs regulate biological processes that influence m6A modifications. This review explores the metabolism and functions of m6A modifications and circRNAs, their interactions, and their specific regulatory mechanisms in different tumors, offering insights into m6A-circRNA interaction in cancer.

circATAD2 mitigates CD8+ T cells antitumor immune surveillance in breast cancer via IGF2BP3/m6A/PD-L1 manner

Immune surveillance and chemotherapy sensitivity play critical functions in the tumorigenesis of breast cancer (BC). Emerging findings have indicated that circular RNA (circRNA) and N6-methyladenosine (m6A) both participate in the BC tumorigenesis. Here, present study aimed to investigate the roles of m6A-modified circATAD2 on BC and explore better understanding for BC precision therapeutic. Results reported that m6A-modifid circRNA (m6A-circRNA) microarray revealed the m6A-circRNA landscape in BC. M6A-modifid circATAD2 upregulated in BC samples and was closely correlated to poor prognosis. Functionally, circATAD2 promoted the immune evasion of BC cells and reduced the CD8+ T cells' killing effect. Mechanistically, MeRIP-seq unveiled the m6A modification in the 3'-UTR of PD-L1 mRNA, which was bound by circATAD2 and recognized by m6A reader IGF2BP3 to enhance PD-L1 mRNA stability and expression. In summary, these findings revealed the circATAD2/m6A/IGF2BP3/PD-L1 axis in BC immune surveillance, suggesting the potential that circATAD2 as a potential target for PD-L1-mediated BC.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

Novel Insights into the Links between N6-Methyladenosine and Regulated Cell Death in Musculoskeletal Diseases

Musculoskeletal diseases (MSDs), including osteoarthritis (OA), osteosarcoma (OS), multiple myeloma (MM), intervertebral disc degeneration (IDD), osteoporosis (OP), and rheumatoid arthritis (RA), present noteworthy obstacles associated with pain, disability, and impaired quality of life on a global scale. In recent years, it has become increasingly apparent that N6-methyladenosine (m6A) is a key regulator in the expression of genes in a multitude of biological processes. m6A is composed of 0.1-0.4% adenylate residues, especially at the beginning of 3'-UTR near the translation stop codon. The m6A regulator can be classified into three types, namely the "writer", "reader", and "eraser". Studies have shown that the epigenetic modulation of m6A influences mRNA processing, nuclear export, translation, and splicing. Regulated cell death (RCD) is the autonomous and orderly death of cells under genetic control to maintain the stability of the internal environment. Moreover, distorted RCDs are widely used to influence the course of various diseases and receiving increasing attention from researchers. In the past few years, increasing evidence has indicated that m6A can regulate gene expression and thus influence different RCD processes, which has a central role in the etiology and evolution of MSDs. The RCDs currently confirmed to be associated with m6A are autophagy-dependent cell death, apoptosis, necroptosis, pyroptosis, ferroptosis, immunogenic cell death, NETotic cell death and oxeiptosis. The m6A-RCD axis can regulate the inflammatory response in chondrocytes and the invasive and migratory of MM cells to bone remodeling capacity, thereby influencing the development of MSDs. This review gives a complete overview of the regulatory functions on the m6A-RCD axis across muscle, bone, and cartilage. In addition, we also discuss recent advances in the control of RCD by m6A-targeted factors and explore the clinical application prospects of therapies targeting the m6A-RCD in MSD prevention and treatment. These may provide new ideas and directions for understanding the pathophysiological mechanism of MSDs and the clinical prevention and treatment of these diseases.

PRMT6-mediated transcriptional activation of ythdf2 promotes glioblastoma migration, invasion, and emt via the wnt-β-catenin pathway

BACKGROUND

Protein arginine methyltransferase 6 (PRMT6) plays a crucial role in various pathophysiological processes and diseases. Glioblastoma (GBM; WHO Grade 4 glioma) is the most common and lethal primary brain tumor in adults, with a prognosis that is extremely poor, despite being less common than other systemic malignancies. Our current research finds PRMT6 upregulated in GBM, enhancing tumor malignancy. Yet, the specifics of PRMT6's regulatory processes and potential molecular mechanisms in GBM remain largely unexplored.

METHODS

PRMT6's expression and prognostic significance in GBM were assessed using glioma public databases, immunohistochemistry (IHC), and immunoblotting. Scratch and Transwell assays examined GBM cell migration and invasion. Immunoblotting evaluated the expression of epithelial-mesenchymal transition (EMT) and Wnt-β-catenin pathway-related proteins. Dual-luciferase reporter assays and ChIP-qPCR assessed the regulatory relationship between PRMT6 and YTHDF2. An in situ tumor model in nude mice evaluated in vivo conditions.

RESULTS

Bioinformatics analysis indicates high expression of PRMT6 and YTHDF2 in GBM, correlating with poor prognosis. Functional experiments show PRMT6 and YTHDF2 promote GBM migration, invasion, and EMT. Mechanistic experiments reveal PRMT6 and CDK9 co-regulate YTHDF2 expression. YTHDF2 binds and promotes the degradation of negative regulators APC and GSK3β mRNA of the Wnt-β-catenin pathway, activating it and consequently enhancing GBM malignancy.

CONCLUSIONS

Our results demonstrate the PRMT6-YTHDF2-Wnt-β-Catenin axis promotes GBM migration, invasion, and EMT in vitro and in vivo, potentially serving as a therapeutic target for GBM.

Ginger inhibits the invasion of ovarian cancer cells SKOV3 through CLDN7, CLDN11 and CD274 m6A methylation modifications

BACKGROUND

Ginger is a common aromatic vegetable with a wide range of functional ingredients and considerable medicinal and nutritional properties. Numerous studies have shown that ginger and its active ingredients have suppressive effects on manifold tumours, including ovarian cancer (OC). However, the molecular mechanism by which ginger inhibits OC is not clear. The aim of this study was to investigate the function and mechanism of ginger in OC.

METHODS

The estimation of n6-methyladenosine (m6A) levels was performed using the m6A RNA Methylation Quantification Kit, and RT-qPCR was used to determine the expression of m6A-related genes and proteins. The m6A methylationome was detected by MeRIP-seq, following analysis of the data. Differential methylation of genes was assessed utilizing RT-qPCR and Western Blotting. The effect of ginger on SKOV3 invasion in ovarian cancer cells was investigated using the wound healing assay and transwell assays.

RESULTS

Ginger significantly reduced the m6A level of OC cells SKOV3. The 3'UTR region is the major site of modification for m6A methylation, and its key molecular activities include Cell Adhesion Molecules, according to meRIP-seq results. Moreover, it was observed that Ginger aids significantly in downregulating the CLDN7, CLDN11 mRNA, and protein expression. The results of wound healing assay and transwell assay showed that ginger significantly inhibited the invasion of OC cells SKOV3.

CONCLUSIONS

Ginger inhibits ovarian cancer cells' SKOV3 invasion by regulating m6A methylation through CLDN7, CLDN11, and CD274.

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

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

METTL3-mediated methylation of CYP2C19 mRNA may aggravate clopidogrel resistance in ischemic stroke patients

Background

N6-methyladenosine (m6A) is the most frequently occurring interior modification in eukaryotic messenger RNA (mRNA), and abnormal mRNA modifications can affect many biological processes. However, m6A's effect on the metabolism of antiplatelet drugs for the prevention of ischemic stroke (IS) remains largely unclear.

Methods

We analyzed the m6A enzymes and m6A methylation in peripheral blood samples of IS patients with/without clopidogrel resistance (CR), and the peripheral blood and liver of rat models with/without CR. We also compared the effect of m6A methylation on the expression of the drug-metabolizing enzymes (CYP2C19 and CYP2C6v1) in CR and non-CR samples.

Results

Methyltransferase-like 3 (METTL3), an m6A enzyme, was highly expressed in the peripheral blood of patients with CR, and in both the peripheral blood and liver of rats with CR. This enzyme targets CYP2C19 or CYP2C6v1 mRNA through m6A methylation, resulting in low expression of CYP2C19 or CYP2C6v1 mRNA. Consequently, this leads to decreased clopidogrel metabolism and CR.

Conclusion

The METTL3-mediated methylation of CYP2C19 mRNA may aggravate CR in IS patients.

IGF2BP3 loss inhibits cell progression by upregulating has_circRNA_103820, and hsa_circRNA_103820-encoded peptide inhibits cell progression by inactivating the AKT pathway in lung cancer

N6-methyladenosine (m6A) modification and m6A-related RNA-binding proteins (RBPs) play vital roles in various aspects of circRNA metabolism. Hsa_circRNA_103820 is implicated in the pathogenesis of multiple cancers, including lung cancer (LC). Moreover, bioinformatics analysis has suggested that hsa_circRNA_103820 possesses potential peptide-coding ability. Thus, we aimed to investigate the function and peptide-coding potential of hsa_circRNA_103820 in this study. Cell viability, apoptosis rate, and migratory and invasive abilities were assessed using CCK-8, flow cytometry, and transwell assays, respectively. Hsa_circRNA_103820 level was measured using RT-qPCR assay, and the interaction between hsa_circRNA_103820 and IGF2BP3 was examined through RIP and RT-qPCR assays. The coding ability of hsa_circRNA_103820 and protein levels were determined through western blot assay. The results showed that hsa_circRNA_103820 reduced cell viability, attenuated cell migratory and invasive abilities, and promoted cell apoptosis in LC. IGF2BP3 negatively regulated hsa_circRNA_103820 expression and interacted with it. Hsa_circRNA_103820 knockdown alleviated si-IGF2BP3-mediated anti-viability, anti-migration, anti-invasion, and pro-apoptosis effects in LC cells. Moreover, a 188-amino acid (aa) peptide encoded by hsa_circRNA_103820 decreased cell viability, facilitated cell apoptosis, and inhibited cell migration and invasion in LC. Collectively, hsa_circRNA_103820, regulated by IGF2BP3, encodes a 188-aa peptide and inhibits the malignant progression of LC cells by inhibiting the AKT pathway.

Regulation of ULK1 by WTAP/IGF2BP3 axis enhances mitophagy and progression in epithelial ovarian cancer

There is a pressing need for innovative therapeutic strategies for patients with epithelial ovarian cancer (EOC). Previous studies have shown that UNC-51-like kinase 1 (ULK1), a serine/threonine kinase, is crucial in regulating cellular autophagy and mitophagy across various tumor types. However, the clinical implications, biological functions, and potential mechanisms of ULK1 in EOC remain poorly understood. This study demonstrates that ULK1 expression is upregulated in EOC tissue samples and EOC cell lines, with increased ULK1 expression correlating with poor prognosis. Functionally, overexpressed ULK1 enhances the proliferation and migration abilities of EOC cells both in vitro and in vivo. Mechanistically, ULK1 was identified as an m6A target of WTAP. WTAP-mediated m6A modification of ULK1 enhanced its mRNA stability in an IGF2BP3-dependent manner, leading to elevated ULK1 expression and enhanced mitophagy in EOC. In summary, our research reveals that the WTAP/IGF2BP3-ULK1 axis significantly influences protective mitophagy in EOC, contributing to its progression. Therefore, the regulatory mechanisms and biological function of ULK1 identify it as a potential molecular target for therapeutic intervention in EOC.

m6A-modified circ_0124554 promotes colorectal cancer progression and radioresistance through the miR-1184/LASP1 pathway

BACKGROUND

Circular RNAs (circRNAs) are believed to regulate the progression of various cancers including colorectal cancer (CRC). However, the role and mechanism of circ_0124554 in regulating the sensitivity of CRC to radiation remain unknown.

METHODS

The RNA levels of circ_0124554, LIM and SH3 protein 1 (LASP1), and methyltransferase 3, N6-adenosine-methyltransferase complex catalytic subunit (METTL3) were detected by quantitative real-time polymerase chain reaction. Protein expression was checked by western blot. Cell proliferation, apoptosis, migration, and invasion were investigated by 5-Ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry analysis, and transwell assay, respectively. The sensitivity of CRC cells to radiation was analyzed by cell colony formation assay. Xenograft mouse model assay was conducted to disclose the role of circ_0001023 in the sensitivity of tumors to radiation in vivo. The binding relationships among circ_0124554, miR-1184 and LASP1 were confirmed by a dual-luciferase reporter assay. m6A RNA immunoprecipitation assay was performed to identify the association of METTL3 with circ_0124554.

RESULTS

Circ_0124554 expression was upregulated in CRC tissues and cells in comparison with normal colorectal tissues and cells. Circ_0124554 knockdown inhibited proliferation, migration and invasion and promoted apoptosis and radiosensitivity of CRC cells. Moreover, circ_0124554 depletion inhibited tumor formation and improved radiosensitivity in vivo. MiR-1184 was identified as a target miRNA of circ_0124554 and targeted LASP1. Additionally, LASP1 overexpression rescued circ_0124554 knockdown-mediated effects in CRC cells. METTL3 mediated m6A methylation of circ_0124554. Further, circ_0124554 overexpression attenuated METTL3 depletion-induced effects in CRC cells.

CONCLUSION

m6A-modified circ_0124554 promoted CRC progression and radioresistance by inducing LASP1 expression through interaction with miR-1184.

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

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

Isovitexin alleviates hepatic fibrosis by regulating miR-21-mediated PI3K/Akt signaling and glutathione metabolic pathway: based on transcriptomics and metabolomics

BACKGROUND

Effective drugs for the treatment of hepatic fibrosis have not yet been identified. Isovitexin (IVT) is a promising hepatoprotective agent owing to its efficacy against acute liver injury. However, the role of IVT in liver fibrosis has not been reported.

PURPOSE

To explore the effect of IVT on liver fibrosis both in vitro and in vivo.

STUDY DESIGN AND METHODS

A mouse model of liver fibrosis induced by carbon tetrachloride (CCl4) and two types of hepatic stellate cell models induced by platelet-derived growth factor-BB (PDGF-BB) were established to evaluate the effect of IVT on hepatic fibrosis. Transcriptomics and metabolomics were used to predict the underlying targets of IVT and were validated by a combination of in vitro and in vivo experiments. Exploration of miRNA and N6-methyladenosine (m6A) modifications was also carried out to detect the key upstream targets of the above targets.

RESULTS

IVT reduced collagen deposition and hepatic stellate cell activation to alleviate liver fibrosis. The transcriptomics and metabolomics analyses showed that phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling and the glutathione (GSH) metabolic pathway may be the main regulatory processes of IVT in hepatic fibrosis. Both the in vitro and in vivo experiments confirmed the inhibitory effect of IVT on the PTEN-PI3K-Akt-mTOR axis and activation of the GSH metabolic pathway. A miR-21 mimic inhibited the effects of IVT on these two pathways, suggesting that miR-21 is the hub for IVT regulation of PI3K-Akt signaling and the GSH metabolic pathway. IVT also increased pri-miR-21 level and reduced the m6A enrichment of pri-miR-21, demonstrating that IVT may regulate pri-miR-21 through m6A modification, thereby affecting the maturation of miR-21.

CONCLUSION

This study is the first to propose a protective effect of IVT against liver fibrosis. The mechanism of IVT against hepatic fibrosis is based on the regulation of miR-21, targeting PTEN-Akt signaling and the GSH metabolic pathway, which is also a novel discovery.

Smoking-Induced M2-TAMs, via circEML4 in EVs, Promote the Progression of NSCLC through ALKBH5-Regulated m6A Modification of SOCS2 in NSCLC Cells

Lung cancer is a commonly diagnosed disease worldwide, with non-small cell lung cancers (NSCLCs) accounting for ≈ 85% of cases. Cigarette smoke is an environmental exposure promoting progression of NSCLC, but its role is poorly understood. This study reports that smoking-induced accumulation of M2-type tumor-associated macrophages (M2-TAMs) surrounding NSCLC tissues promotes malignancy. Specifically, extracellular vesicles (EVs) from cigarette smoke extract (CSE)-induced M2 macrophages promoted malignancy of NSCLC cells in vitro and in vivo. circEML4 in EVs from CSE-induced M2 macrophages is transported to NSCLC cells, where it reduced the distribution of ALKBH5 in the nucleus by interacting with Human AlkB homolog H5 (ALKBH5), resulting in elevated N6-methyladenosine (m6A) modifications. m6A-seq and RNA-seq revealed suppressor of cytokine signaling 2 (SOCS2)-mediated activation of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway by regulating m6A modification of SOCS2 via ALKBH5. Down-regulation of circEML4 in EVs from CSE-induced M2 macrophages reversed EVs-enhanced tumorigenicity and metastasis in NSCLC cells. Furthermore, this study found that smoking patients showed an increase in circEML4-positive M2-TAMs. These results indicate that smoking-induced M2-TAMs via circEML4 in EVs promote the NSCLC progression through ALKBH5-regulated m6A modification of SOCS2. This study also reveals that circEML4 in EVs from TAMs acts as a diagnostic biomarker for NSCLC, especially for patients with smoking history.

Macrophage membrane-coated nanovesicles for dual-targeted drug delivery to inhibit tumor and induce macrophage polarization

Background

Immunosuppressive M2 macrophages in the tumor microenvironment (TME) can mediate the therapeutic resistance of tumors, and seriously affect the clinical efficacy and prognosis of tumor patients. This study aims to develop a novel drug delivery system for dual-targeting tumor and macrophages to inhibit tumor and induce macrophage polarization.

Methods

The anti-tumor effects of methyltransferase like 14 (METTL14) were investigated both in vitro and in vivo. The underlying mechanisms of METTL14 regulating macrophages were also explored in this study. We further constructed the cyclic (Arg-Gly-Asp) (cRGD) peptide modified macrophage membrane-coated nanovesicles to co-deliver METTL14 and the TLR4 agonist.

Results

We found that METTL14 significantly inhibits the growth of tumor in vitro. METTL14 might downregulate TICAM2 and inhibit the Toll-like receptor 4 (TLR4) pathway of macrophages, meanwhile, the combination of METTL14 and the TLR4 agonist could induce M1 polarization of macrophages. Macrophage membrane-coated nanovesicles are characterized by easy modification, drug loading, and dual-targeting tumor and macrophages, and cRGD modification can further enhance its targeting ability. It showed that the nanovesicles could improve the in vivo stability of METTL14, and dual-target tumor and macrophages to inhibit tumor and induce M1 polarization of macrophages.

Conclusions

This study anticipates achieving the dual purposes of tumor inhibition and macrophage polarization, and providing a new therapeutic strategy for tumors.

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Methyltransferase like 14 (METTL14) significantly inhibits the growth of tumor in vitro.

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The combination of METTL14 and TLR4 agonist could induce M1 polarization of macrophages.

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We constructed the cyclic (Arg-Gly-Asp) (cRGD) peptide modified macrophage membrane-coated nanovesicles to co-deliver METTL14 and TLR4 agonist.

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This nanovesicles could dual-target tumor and macrophages to inhibit tumor and induce M1 polarization of macrophages.

METTL14 Facilitates the Metastasis of Pancreatic Carcinoma by Stabilizing LINC00941 in an m6A-IGF2BP2-Dependent Manner

Pancreatic adenocarcinoma (PC), one of the most fatal diseases, usually generates a poor prognosis in advanced stages. N6-methyladenosine modification has emerged as a crucial participant in tumor development and recurrence. Methyltransferase-like 14 (METTL14), as a core member of methyltransferases, is involved in tumor progression and metastasis. However, the potential mechanism by which METTL14 regulates long noncoding RNAs (lncRNAs) in PC remains unclear. RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation quantitative PCR (MeRIP-qPCR), and fluorescence in situ hybridization (FISH) were used to explore the underlying mechanisms. In our study, we found that METTL14 expression was upregulated in PC patients, and was associated with poor prognosis. In vitro and in vivo experiments, knocking down METTL14 suppressed tumor metastasis. RNA-seq and bioinformatics analyses were used to identify LINC00941 as the downstream target of METTL14. Mechanistically, LINC00941 was upregulated by METTL14 in an m6A-dependent way. LINC00941 was recruited and recognized by IGF2BP2. METTL14 enhanced the affinity of IGF2BP2 for LINC00941, while IGF2BP2 promoted the stabilization of LINC00941, which contributed to the migration and invasion of PC cells. Overall, our research revealed that METTL14 promoted the metastasis of PC through m6A modification of LINC00941. Targeting the METTL14-LINC00941-IGF2BP2 axis may provide promising therapeutic approaches for PC.

Emerging landscape of circFNDC3B and its role in human malignancies

In recent years, more attention has been paid to expanding the abundance of Circular RNAs (circRNAs), while the circRNAs that have been found to have significant functions have not been studied in different diseases. CircFNDC3B is one of the most researched circRNAs generated from fibronectin type III domain-containing protein 3B (FNDC3B) gene. Accumulating researches have reported the multiple functions of circFNDC3B in different cancer types and other non-neoplastic diseases, and predicted that circFNDC3B might be a potential biomarker. Notably, circFNDC3B can play roles in different diseases by binding to various microRNAs (miRNAs), binding to RNA-binding proteins (RBPs), or encoding functional peptides. This paper systematically summarizes the biogenesis and function of circRNAs, reviews and discusses the roles and molecular mechanisms of circFNDC3B and its target genes in different cancers and non-neoplastic diseases, which will do favor to broaden our comprehension of the function of circRNAs and facilitate subsequent research on circFNDC3B.

m6A-modified circFOXK2 targets GLUT1 to accelerate oral squamous cell carcinoma aerobic glycolysis

N⁶-methyladenosine (m⁶A) is an abundant nucleotide modification in mRNA, and its emerging roles have been gradually identified. However, the potential function of m⁶A and m⁶A-modified circular RNA (circRNA) is still unclear. Here, m⁶A-circRNA epitranscriptomic microarray analysis revealed a high-expressed m⁶A-modified circFOXK2 (hsa_circ_0000816, from FOXK2 gene) in oral squamous cell carcinoma (OSCC). For the biofunctions of OSCC, results revealed that circFOXK2 promoted the malignant phenotypes of OSCC cells. Methylated RNA immunoprecipitation sequencing (MeRIP-Seq) demonstrated that a remarkable m⁶A modified site was installed on glucose transporter 1 (GLUT1) mRNA. Mechanistically, circFOXK2 promoted the GLUT1 mRNA stability through cooperating with insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) in a m⁶A-dependent manner. In summary, the present study explored the oncogenic role of m⁶A-modified circFOXK2 in OSCC through the m⁶A-dependent IGF2BP3/GLUT1 axis, indicating a potential therapeutic target for OSCC.

Mutual regulation between N6-methyladenosine (m6A) modification and circular RNAs in cancer: impacts on therapeutic resistance

The resistance of tumor cells to therapy severely impairs the efficacy of treatment, leading to recurrence and metastasis of various cancers. Clarifying the underlying mechanisms of therapeutic resistance may provide new strategies for overcoming cancer resistance. N6-methyladenosine (m6A) is the most prevalent RNA modification in eukaryotes, and is involved in the regulation of RNA splicing, translation, transport, degradation, stability and processing, thus affecting several physiological processes and cancer progression. As a novel type of multifunctional non-coding RNAs (ncRNAs), circular RNAs (circRNAs) have been demonstrated to play vital roles in anticancer therapy. Currently, accumulating studies have revealed the mutual regulation of m6A modification and circRNAs, and their interaction can further influence the sensitivity of cancer treatment. In this review, we mainly summarized the recent advances of m6A modification and circRNAs in the modulation of cancer therapeutic resistance, as well as their interplay and potential mechanisms, providing promising insights and future directions in reversal of therapeutic resistance in cancer.

Unpacking extracellular vesicles: RNA cargo loading and function

Extracellular vesicles (EVs) are a heterogeneous group of membrane-enclosed structures produced by prokaryotic and eukaryotic cells. EVs carry a range of biological cargoes, including RNA, protein, and lipids, which may have both metabolic significance and signalling potential. EV release has been suggested to play a critical role in maintaining intracellular homeostasis by eliminating unnecessary biological material from EV producing cells, and as a delivery system to enable cellular communication between both neighbouring and distant cells without physical contact. In this review, we give an overview of what is known about the relative enrichment of the different types of RNA that have been associated with EVs in the most recent research efforts. We then examine the selective and non-selective incorporation of these different RNA biotypes into EVs, the molecular systems of RNA sorting into EVs that have been elucidated so far, and the role of this process in EV-producing cells. Finally, we also discuss the model systems providing evidence for EV-mediated delivery of RNA to recipient cells, and the implications of this evidence for the relevance of this RNA delivery process in both physiological and pathological scenarios.