Small-molecule inhibition of the METTL3/METTL14 complex suppresses neuroblastoma tumor growth and promotes differentiation

Deciphering the interplay between SETD2 mediated H3K36me3 and RNA N6-methyladenosine in clear cell renal cell carcinoma (ccRCC)

RNA N6-methyladenosine (m6A) plays diverse roles in RNA metabolism and its deregulation contributes to tumor initiation and progression. Clear cell renal cell carcinoma (ccRCC) is characterized by near ubiquitous loss of VHL followed by mutations in epigenetic regulators PBRM1, SETD2, and BAP1. Mutations in SETD2, a histone H3 lysine 36 trimethylase (H3K36me3), are associated with reduced survival, greater metastatic propensity, and metabolic reprogramming. While m6A and H3K36me3 deregulation are separately implicated in renal tumorigenesis, H3K36me3 may participate directly in m6A targeting, but the m6A-H3K36me3 interplay has not been investigated in the context of ccRCC. Using RCC-relevant SETD2 isogenic knockout and rescue cell line models, we demonstrate a dynamic redistribution of m6A in the SETD2 depleted transcriptome, with a subset of transcripts involved in metabolic reprogramming demonstrating SETD2 dependent m6A and expression level changes. Using a panel of six histone modifications we show that m6A redistributes to regions enriched in gained active enhancers upon SETD2 inactivation. Finally, we demonstrate a reversal of transcriptomic programs involved in SETD2 loss mediated metabolic reprogramming, and reduced cell viability through pharmacologic inhibition or genetic ablation of m6A writer METTL3 specific to SETD2 deficient cells. Thus, targeting m6A may represent a novel therapeutic vulnerability in SETD2 mutant ccRCC.

Reciprocal regulation between m6 A modifications and non-coding RNAs: emerging roles in cancer therapeutic resistance

In recent years, the interplay between N6-methyladenosine (m6A) modifications and non-coding RNAs (ncRNAs) has emerged as a pivotal research area, owing to their crucial involvement in the pathophysiological mechanisms underlying various diseases. A significant hurdle in cancer therapy is therapeutic resistance, which frequently contributes to adverse patient outcomes. Recent investigations have underscored the vital role that interactions between m6A modifications and ncRNAs play in mediating cancer therapeutic resistance via the MAPK, PI3K/Akt/mTOR, Wnt/β-catenin, HIPPO, and NF-κB pathways. This review elucidates how these interactions drive tumor therapeutic resistance by modulating these pathways. By dissecting the regulatory dynamics between m6A and ncRNAs in the context of cancer therapeutic resistance, this review aims to deepen the understanding of m6A-ncRNA interaction in cancer therapeutic resistance and identify potential therapeutic targets to improve cancer treatment efficacy.

METTL3 Promotes Cutaneous T-Cell Lymphoma Progression by Regulating ARHGEF12 Expression

Recent studies have identified N6-methyladenosine (m6A) RNA methylation as a key regulatory mechanism in tumor progression. This study aimed to elucidate the biological function and clinical relevance of the m6A methyltransferase METTL3 in cutaneous T-cell lymphoma (CTCL). Our findings demonstrated that METTL3 expression is upregulated in CTCL, and its knockdown suppresses CTCL progression. Mechanistically, the downregulation of METTL3-mediated m6A modification on ARHGEF12 mRNA accelerated its degradation, a process that is closely associated with tumor behaviors. These results suggest that METTL3 may serve as a potential therapeutic target in CTCL.

METTL3, an Independent Adverse Prognostic Factor for AML, Promotes the Development of AML by Modulating the PGC-1α-MAPK Pathway and PGC-1α-Antioxidant System Axis

BACKGROUND

m6A represents a prevalent epigenetic modification of mammalian mRNAs. Studies have demonstrated that m6A RNA methylation-modifying enzymes play crucial roles in the onset and progression of AML. However, their clinical relevance remains undefined, and the mechanisms underlying their modulation of AML have yet to be elucidated.

RESULTS

The expression levels of the m6A RNA-modifying enzymes METTL3, METTL14, WTAP, FTO and ALKBH5 were elevated in AML patients. METTL3-positive AML is often accompanied by DNMT3A mutations and is also an independent poor prognostic factor for AML patients. Following METTL3 knockdown, we observed a decrease in the m6A level of the mitochondrial oxidative stress gene PGC-1α in K562 and MV4-11 cells. We analyzed the expression levels of PGC-1α and METTL3 mRNA in 105 patients with primary AML. The expression levels of PGC-1α and METTL3 mRNA were positively correlated. Similar to METTL3 knockdown, PGC-1α gene knockdown resulted in increased phosphorylation of the key signaling molecules P38, c-Jun and ERK1/2 in the MAPK signaling pathway, and decreased mRNA levels of SOD1, GPX1, catalase and UCP2 in the antioxidant system of K562 cells. Analysis of the TCGA and GSE13159 datasets, along with samples from West China Hospital, revealed that patients exhibiting high PGC-1α expression had a poor prognosis.

CONCLUSION

The m6A methylation-modifying enzyme METTL3 is an independent prognostic factor for poor prognosis in AML patients. PGC-1α is a downstream signaling molecule of METTL3, and METTL3 affects its expression by regulating the m6A level of PGC-1α. PGC-1α acts as an oncogene in AML by affecting the MAPK pathway and antioxidant system.

METTL14 regulates proliferation and differentiation of duck myoblasts through targeting MiR-133b

The development of duck pectoral muscle has a significant impact on meat quality, and miRNA and m6A modification play key roles in this process. In the early stage, by using MeRIP-seq and miRNA-seq to analyze the pectoral muscle tissue of duck embryos at day 13 (E13), day 19 (E19), and day 27 (E27) of incubation, we found that METTL14, as a core component of the m6A methylation transferase complex, showed significant differences in expression at different developmental stages and may have an important impact on pectoral muscle development. In this study, qRT-PCR detection revealed that the expression of proliferation and differentiation marker genes CDK2, CyclinD1, MYOG and MYHC varied at different stages, with the highest m6A level at E13 and the lowest expression of METTL14 at the same stage. After constructing overexpression and interference vectors for METTL14, we found that METTL14 interference promoted the proliferation of duck embryo myoblasts and inhibited differentiation, while overexpression inhibited proliferation and accelerated differentiation. In particular, the overexpression of METTL14 increased the expression of miR-133b, whose precursor sequence contains m6A modification sites, suggesting that METTL14 may participate in the regulation of muscle development by affecting the expression of miR-133b. This study provides new insights into the molecular mechanisms of duck pectoral muscle development and offers potential molecular targets for the genetic improvement of duck pectoral muscle.

METTL3 confers oxaliplatin resistance through the activation of G6PD-enhanced pentose phosphate pathway in hepatocellular carcinoma

Oxaliplatin-based therapeutics is a widely used treatment approach for hepatocellular carcinoma (HCC) patients; however, drug resistance poses a significant clinical challenge. Epigenetic modifications have been implicated in the development of drug resistance. In our study, employing siRNA library screening, we identified that silencing the m6A writer METTL3 significantly enhanced the sensitivity to oxaliplatin in both in vivo and in vitro HCC models. Further investigations through combined RNA-seq and non-targeted metabolomics analysis revealed that silencing METTL3 impeded the pentose phosphate pathway (PPP), leading to a reduction in NADPH and nucleotide precursors. This disruption induced DNA damage, decreased DNA synthesis, and ultimately resulted in cell cycle arrest. Mechanistically, METTL3 was found to modify E3 ligase TRIM21 near the 3'UTR with N6-methyladenosine, leading to reduced RNA stability upon recognition by YTHDF2. TRIM21, in turn, facilitated the degradation of the rate-limiting enzyme of PPP, G6PD, through the ubiquitination-proteasome pathway. Importantly, high expression of METTL3 was significantly associated with adverse prognosis and oxaliplatin resistance in HCC patients. Notably, treatment with the specific METTL3 inhibitor, STM2457, significantly improved the efficacy of oxaliplatin. These findings underscore the critical role of the METTL3/TRIM21/G6PD axis in driving oxaliplatin resistance and present a promising strategy to overcome chemoresistance in HCC.

Patent landscape of small molecule inhibitors of METTL3 (2020-present)

INTRODUCTION

Methyltransferase-like protein 3 (METTL3), in complex with METTL14, is the key 'writer' protein for RNA m6A methylation, accounting for almost all mRNA m6A modifications. Recent studies reveal that METTL3 is implicated in the development and progression of various types of cancers. Targeting METTL3 with small molecule inhibitors represents a promising therapeutic strategy for cancer.

AREAS COVERED

This review provides an overview of the patent literature covering METTL3 inhibitors. A literature search was conducted in SciFinder by using 'METTL3 inhibitor' as a keyword and was refined by narrowing the criteria to patents.

EXPERT OPINION

Efforts to develop METTL3/METTL14 inhibitors have led to the advancement of the drug candidate STC-15 to clinical trials. Preclinical studies of STC-15 show promise in inhibiting tumor growth via direct anti-tumor effects and anti-cancer immune responses. The clinical trial outcomes of STC-15 will shape future METTL3/METTL14 inhibitor development. However, critical questions remain. The role of METTL3/METTL14 in m6A RNA methylation is essential for cellular activity, raising concerns about the potential adverse effects of targeting this complex. Furthermore, depending on the context, METTL3/METTL14 can function as a tumor suppressor. This underscores the need for a deeper understanding of the molecular mechanisms by which RNA modifications regulate cancer.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

Clinician's Guide to Epitranscriptomics: An Example of N1-Methyladenosine (m1A) RNA Modification and Cancer

Epitranscriptomics is the study of modifications of RNA molecules by small molecular residues, such as the methyl (-CH3) group. These modifications are inheritable and reversible. A specific group of enzymes called "writers" introduces the change to the RNA; "erasers" delete it, while "readers" stimulate a downstream effect. Epitranscriptomic changes are present in every type of organism from single-celled ones to plants and animals and are a key to normal development as well as pathologic processes. Oncology is a fast-paced field, where a better understanding of tumor biology and (epi)genetics is necessary to provide new therapeutic targets and better clinical outcomes. Recently, changes to the epitranscriptome have been shown to be drivers of tumorigenesis, biomarkers, and means of predicting outcomes, as well as potential therapeutic targets. In this review, we aimed to give a concise overview of epitranscriptomics in the context of neoplastic disease with a focus on N1-methyladenosine (m1A) modification, in layman's terms, to bring closer this omics to clinicians and their future clinical practice.

Regulatory effect of N6-methyladenosine on tumor angiogenesis

Previous studies have demonstrated that genetic alterations governing epigenetic processes frequently drive tumor development and that modifications in RNA may contribute to these alterations. In the 1970s, researchers discovered that N6-methyladenosine (m6A) is the most prevalent form of RNA modification in advanced eukaryotic messenger RNA (mRNA) and noncoding RNA (ncRNA). This modification is involved in nearly all stages of the RNA life cycle. M6A modification is regulated by enzymes known as m6A methyltransferases (writers) and demethylases (erasers). Numerous studies have indicated that m6A modification can impact cancer progression by regulating cancer-related biological functions. Tumor angiogenesis, an important and unregulated process, plays a pivotal role in tumor initiation, growth, and metastasis. The interaction between m6A and ncRNAs is widely recognized as a significant factor in proliferation and angiogenesis. Therefore, this article provides a comprehensive review of the regulatory mechanisms underlying m6A RNA modifications and ncRNAs in tumor angiogenesis, as well as the latest advancements in molecular targeted therapy. The aim of this study is to offer novel insights for clinical tumor therapy.

Role of N6-methyladenosine RNA modification in cancer

N6-methyladenosine (m6A) is the most abundant modification of RNA in eukaryotic cells. Previous studies have shown that m6A is pivotal in diverse diseases especially cancer. m6A corelates with the initiation, progression, resistance, invasion, and metastasis of cancer. However, despite these insights, a comprehensive understanding of its specific roles and mechanisms within the complex landscape of cancer is still elusive. This review begins by outlining the key regulatory proteins of m6A modification and their posttranslational modifications (PTMs), as well as the role in chromatin accessibility and transcriptional activity within cancer cells. Additionally, it highlights that m6A modifications impact cancer progression by modulating programmed cell death mechanisms and affecting the tumor microenvironment through various cancer-associated immune cells. Furthermore, the review discusses how microorganisms can induce enduring epigenetic changes and oncogenic effect in microorganism-associated cancers by altering m6A modifications. Last, it delves into the role of m6A modification in cancer immunotherapy, encompassing RNA therapy, immune checkpoint blockade, cytokine therapy, adoptive cell transfer therapy, and direct targeting of m6A regulators. Overall, this review clarifies the multifaceted role of m6A modification in cancer and explores targeted therapies aimed at manipulating m6A modification, aiming to advance cancer research and improve patient outcomes.

METTL Family in Healthy and Disease

Transcription, RNA splicing, RNA translation, and post-translational protein modification are fundamental processes of gene expression. Epigenetic modifications, such as DNA methylation, RNA modifications, and protein modifications, play a crucial role in regulating gene expression. The methyltransferase-like protein (METTL) family, a constituent of the 7-β-strand (7BS) methyltransferase subfamily, is broadly distributed across the cell nucleus, cytoplasm, and mitochondria. Members of the METTL family, through their S-adenosyl methionine (SAM) binding domain, can transfer methyl groups to DNA, RNA, or proteins, thereby impacting processes such as DNA replication, transcription, and mRNA translation, to participate in the maintenance of normal function or promote disease development. This review primarily examines the involvement of the METTL family in normal cell differentiation, the maintenance of mitochondrial function, and its association with tumor formation, the nervous system, and cardiovascular diseases. Notably, the METTL family is intricately linked to cellular translation, particularly in its regulation of translation factors. Members represent important molecules in disease development processes and are associated with patient immunity and tolerance to radiotherapy and chemotherapy. Moreover, future research directions could include the development of drugs or antibodies targeting its structural domains, and utilizing nanomaterials to carry miRNA corresponding to METTL family mRNA. Additionally, the precise mechanisms underlying the interactions between the METTL family and cellular translation factors remain to be clarified.

Post-transcriptional regulation as a conserved driver of neural crest and cancer-cell migration

Cells have evolved mechanisms to migrate for diverse biological functions. A process frequently deployed during metazoan cell migration is the epithelial-mesenchymal transition (EMT). During EMT, adherent epithelial cells undergo coordinated cellular transitions to mesenchymalize and reduce their intercellular attachments. This is achieved via tightly regulated changes in gene expression, which modulates cell-cell and cell-matrix adhesion to allow movement. The acquisition of motility and invasive properties following EMT allows some mesenchymal cells to migrate through complex environments to form tissues during embryogenesis; however, these processes may also be leveraged by cancer cells, which often co-opt these endogenous programs to metastasize. Post-transcriptional regulation is now emerging as a major conserved mechanism by which cells modulate EMT and migration, which we discuss here in the context of vertebrate development and cancer.