The m6A methyltransferase METTL3 promotes bladder cancer progression via AFF4/NF-κB/MYC signaling network

The complex roles of m 6 A modifications in neural stem cell proliferation, differentiation, and self-renewal and implications for memory and neurodegenerative diseases

N6-methyladenosine (m 6 A), the most prevalent and conserved RNA modification in eukaryotic cells, profoundly influences virtually all aspects of mRNA metabolism. mRNA plays crucial roles in neural stem cell genesis and neural regeneration, where it is highly concentrated and actively involved in these processes. Changes in m 6 A modification levels and the expression levels of related enzymatic proteins can lead to neurological dysfunction and contribute to the development of neurological diseases. Furthermore, the proliferation and differentiation of neural stem cells, as well as nerve regeneration, are intimately linked to memory function and neurodegenerative diseases. This paper presents a comprehensive review of the roles of m 6 A in neural stem cell proliferation, differentiation, and self-renewal, as well as its implications in memory and neurodegenerative diseases. m 6 A has demonstrated divergent effects on the proliferation and differentiation of neural stem cells. These observed contradictions may arise from the time-specific nature of m 6 A and its differential impact on neural stem cells across various stages of development. Similarly, the diverse effects of m 6 A on distinct types of memory could be attributed to the involvement of specific brain regions in memory formation and recall. Inconsistencies in m 6 A levels across different models of neurodegenerative disease, particularly Alzheimer's disease and Parkinson's disease, suggest that these disparities are linked to variations in the affected brain regions. Notably, the opposing changes in m 6 A levels observed in Parkinson's disease models exposed to manganese compared to normal Parkinson's disease models further underscore the complexity of m 6 A's role in neurodegenerative processes. The roles of m 6 A in neural stem cell proliferation, differentiation, and self-renewal, and its implications in memory and neurodegenerative diseases, appear contradictory. These inconsistencies may be attributed to the time-specific nature of m 6 A and its varying effects on distinct brain regions and in different environments.

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

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

ALKBH5 facilitates the progression of infantile hemangioma by increasing FOXF1 expression in a m6A-YTHDF2 dependent manner to activate HK-2 signaling

Alkylation repair homolog protein 5 (ALKBH5) is reported to participate in infantile hemangioma (IH) progression. However, the underlying mechanism of ALKBH5 in IH remains unclear. Using qRT-PCR and Western blotting, ALKBH5, forkhead box F1 (FOXF1) and hexokinase 2 (HK-2) expressions in IH tissues and IH-derived endothelial cells XPTS-1 were assessed. The Me-RIP assay was used to analyze FOXF1 m6A level. CCK8, colony formation, flow cytometry and transwell assays were employed to determine IH cell viability, proliferation, apoptosis, migration and invasion. The interactions between YTH (YT521-B homology) domain 2 (YTHDF2), FOXF1 and HK-2 were analyzed by RIP, dual luciferase reporter gene assay and/or ChIP assay. The in vivo IH growth was evaluated in immunocompromised mice. FOXF1 was overexpressed in IH tissues, and its silencing inhibited IH cell proliferation, migration and invasion whereas promoting cell apoptosis in vitro. ALKBH5 upregulation facilitated FOXF1 mRNA stability and expression in IH cells in a m6A-YTHDF2-dependent manner. FOXF1 downregulation reversed the impact of ALKBH5 upregulation on IH cellular phenotypes. It also turned out that FOXF1 positively regulated HK-2 expression in IH cells through interacting with the HK-2 promoter. HK-2 upregulation abolished FOXF1 knockdown's inhibition on IH cell aggressive behaviors. ALKBH5 or FOXF1 silencing suppressed IH tumor development via HK-2 signaling in immunocompromised mice. ALKBH5 promoted FOXF1 expression m6A-YTHDF2 dependently, which in turn elevated HK-2 expression, thereby accelerating IH development.

Pan-cancer Analysis Reveals m6A Variation and Cell-specific Regulatory Network in Different Cancer Types

As the most abundant messenger RNA (mRNA) modification, N6-methyladenosine (m6A) plays a crucial role in RNA fate, impacting cellular and physiological processes in various tumor types. However, our understanding of the role of the m6A methylome in tumor heterogeneity remains limited. Herein, we collected and analyzed m6A methylomes across nine human tissues from 97 m6A sequencing (m6A-seq) and RNA sequencing (RNA-seq) samples. Our findings demonstrate that m6A exhibits different heterogeneity in most tumor tissues compared to normal tissues, which contributes to the diverse clinical outcomes in different cancer types. We also found that the cancer type-specific m6A level regulated the expression of different cancer-related genes in distinct cancer types. Utilizing a novel and reliable method called "m6A-express", we predicted m6A-regulated genes and revealed that cancer type-specific m6A-regulated genes contributed to the prognosis, tumor origin, and infiltration level of immune cells in diverse patient populations. Furthermore, we identified cell-specific m6A regulators that regulate cancer-specific m6A and constructed a regulatory network. Experimental validation was performed, confirming that the cell-specific m6A regulator CAPRIN1 controls the m6A level of TP53. Overall, our work reveals the clinical relevance of m6A in various tumor tissues and explains how such heterogeneity is established. These results further suggest the potential of m6A in cancer precision medicine for patients with different cancer types.

Dynamic RNA methylation modifications and their regulatory role in mammalian development and diseases

Among over 170 different types of chemical modifications on RNA nucleobases identified so far, RNA methylation is the major type of epitranscriptomic modifications existing on almost all types of RNAs, and has been demonstrated to participate in the entire process of RNA metabolism, including transcription, pre-mRNA alternative splicing and maturation, mRNA nucleus export, mRNA degradation and stabilization, mRNA translation. Attributing to the development of high-throughput detection technologies and the identification of both dynamic regulators and recognition proteins, mechanisms of RNA methylation modification in regulating the normal development of the organism as well as various disease occurrence and developmental abnormalities upon RNA methylation dysregulation have become increasingly clear. Here, we particularly focus on three types of RNA methylations: N6-methylcytosine (m6A), 5-methylcytosine (m5C), and N7-methyladenosine (m7G). We summarize the elements related to their dynamic installment and removal, specific binding proteins, and the development of high-throughput detection technologies. Then, for a comprehensive understanding of their biological significance, we also overview the latest knowledge on the underlying mechanisms and key roles of these three mRNA methylation modifications in gametogenesis, embryonic development, immune system development, as well as disease and tumor progression.

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.

Refining the role of N6-methyladenosine in cancer

N6-methyladenosine (m6A) is the most abundant internal modification of eukaryotic mRNAs. m6A affects the fate of its targets in all aspects of the mRNA life cycle and has important roles in various physiological and pathophysiological processes. Aberrant m6A patterns have been observed in numerous cancers and appear closely linked to oncogenic phenotypes. However, most studies relied on antibody-dependent modification detection, which is known to suffer from important limitations. Novel, antibody-independent, quantitative approaches will be critical to investigate changes in the m6A landscape of cancers. Furthermore, pharmaceutical targeting of the m6A writer Methyltransferase-like 3 (METTL3) has demonstrated the potential to modulate cancer cell phenotypes. However, the enzyme also appears to be essential for the viability of healthy cells. Further refinement of therapeutic strategies is therefore needed to fully realize the potential of m6A-related cancer therapies.

Interplay of RNA m6A Modification-Related Geneset in Pan-Cancer

Background: N6-methyladenosine (m6A), is the most common modification found in mRNA and lncRNA in higher organisms and plays an important role in physiology and pathology. However, its role in pan-cancer has not been explored. Results: A total of 31 m6A modification regulators, including 12 writers, 2 erasers, and 17 readers are identified in the current study. The functional analysis of the regulators results in the enrichment of processes, primarily related to RNA modification and metabolism, and the PPI network reveals multiple interactions among the regulators. The mRNA expression analysis reveals a high expression for most of the regulators in pan-cancer. Most of the m6A regulators are found to be mutated across the cancers, with ZC3H13, VIRMA, and PRRC2A having a higher frequency rate. Significant correlations of the regulators with clinicopathological parameters, such as age, gender, tumor stage, and grade are identified in pan-cancer. The m6A regulators' expression is found to have significant positive correlations with the miRNAs in pan-cancer. The expression pattern of the m6A regulators is able to classify the tumors into different subclusters as well as into high- and low-risk groups. These tumor groups show differential patterns in terms of their immune cell infiltration, tumor stemness score, genomic heterogeneity score, expression of immune regulatory/checkpoint genes, and correlations between the regulators and the drugs. Conclusions: Our study provide a comprehensive overview of the functional roles, genetic and epigenetic alterations, and prognostic value of the RNA m6A regulators in pan-cancer.

METTL3-Mediated m6A Modification of FMRP Drives Hepatocellular Carcinoma Progression and Indicates Poor Prognosis

Accumulating studies reveal that m6A RNA methylation plays a critical role in cancer pathogenesis and progression. METTL3 as a m6A methyltransferase acts as an oncogene in multiple malignancies including hepatocellular carcinoma (HCC). However, the role and underlying mechanism by which METTL3 contributes to HCC remain unclear. The association of METTL3 expression with clinicopathological characteristics and prognosis in patients with HCC was assessed by reverse transcription polymerase chain reaction, Western blot, and public TCGA dataset. MTT, colony formation, Transwell assays, and xenograft tumor models were executed to reveal the role of METTL3 in HCC. m6A dot blot, RNA immunoprecipitation (RIP), m6A methylated RIP, and Western blot assays were used to uncover the regulatory mechanism of METTL3 in HCC cells. We found that METTL3 was dramatically upregulated in HCC tissue samples and acted as an independent prognostic factor for poor survival and tumor recurrence in patients with HCC. Silencing of METTL3 repressed cell growth and invasion in vitro and in vivo, but restored expression of METTL3 boosted these effects. Mechanistical investigations revealed that METTL3 could directly interact with FMRP and harbor a positive correlation with FMRP expression. Knockdown of METTL3 reduced FMRP m6A levels as well as its mRNA and protein expression. FMRP overexpression drove cell colony formation and cell invasion and abolished METTL3 knockdown-induced antitumor effects and AKT/mTORC1 signaling inactivation. Elevated expression of FMRP could act as an independent prognostic factor for poor survival and tumor recurrence in patients with HCC. Our findings demonstrate that METTL3-mediated m6A modification of FMRP promotes growth and invasion of HCC cells and may provide a promising therapeutic target for HCC.

Azithromycin regulates Mettl3-mediated NF-κB pathway to enhance M2 polarization of RAW264.7 macrophages and attenuate LPS-triggered cytotoxicity of MLE-12 alveolar cells

BACKGROUND

Azithromycin (AZM) has been proposed as a potential therapeutic drug in acute pulmonary injury due to its immunomodulatory and anti-inflammatory properties. However, its therapeutic mechanism remains not fully understood.

METHODS

LPS was used to stimulate MLE-12 cells and RAW264.7 macrophages. Analyses of viability and apoptosis were performed by CCK-8 assay and flow cytometry, respectively. Protein analysis was performed by immunoblotting, and mRNA expression was tested by quantitative PCR. The secretion levels of TNF-α and IL-6 were detected by ELISA. MDA, GSH, ROS and Fe2+ contents were analyzed using assay kits.

RESULTS

Administration of AZM or depletion of methyltransferase-like 3 (Mettl3) could attenuate LPS-triggered apoptosis, inflammation and ferroptosis in MLE-12 alveolar cells, as well as enhance M2 polarization of LPS-stimulated RAW264.7 macrophages. In LPS-exposed MLE-12 and RAW264.7 cells, AZM reduced Mettl3 protein expression and inactivated the NF-κB signaling through downregulation of Mettl3. Furthermore, Mettl3 restoration abated AZM-mediated anti-apoptosis, anti-inflammation and anti-ferroptosis effects in LPS-exposed MLE-12 cells and reversed AZM-mediated M2 polarization enhancement of LPS-exposed RAW264.7 macrophages.

CONCLUSION

Our study indicates that AZM can promote M2 polarization of LPS-exposed RAW264.7 macrophages and attenuate LPS-triggered injury of MLE-12 alveolar cells by inactivating the Mettl3-mediated NF-κB pathway.

The role of the ALKBH5 RNA demethylase in invasive breast cancer

BACKGROUND

N6-methyladenosine (m6A) is the most common internal RNA modification and is involved in regulation of RNA and protein expression. AlkB family member 5 (ALKBH5) is a m6A demethylase. Given the important role of m6A in biological mechanisms, m6A and its regulators, have been implicated in many disease processes, including cancer. However, the contribution of ALKBH5 to invasive breast cancer (BC) remains poorly understood. The aim of this study was to evaluate the clinicopathological value of ALKBH5 in BC.

METHODS

Publicly available data were used to investigate ALKBH5 mRNA alterations, prognostic significance, and association with clinical parameters at the genomic and transcriptomic level. Differentially expressed genes (DEGs) and enriched pathways with low or high ALKBH5 expression were investigated. Immunohistochemistry (IHC) was used to assess ALKBH5 protein expression in a large well-characterised BC series (n = 1327) to determine the clinical significance and association of ALKBH5 expression.

RESULTS

Reduced ALKBH5 mRNA expression was significantly associated with poor prognosis and unfavourable clinical parameters. ALKBH5 gene harboured few mutations and/or copy number alternations, but low ALKBH5 mRNA expression was seen. Patients with low ALKBH5 mRNA expression had a number of differentially expressed genes and enriched pathways, including the cytokine-cytokine receptor interaction pathway. Low ALKBH5 protein expression was significantly associated with unfavourable clinical parameters associated with tumour progression including larger tumour size and worse Nottingham Prognostic Index group.

CONCLUSION

This study implicates ALKBH5 in BC and highlights the need for further functional studies to decipher the role of ALKBH5 and RNA m6A methylation in BC progression.

Decoding the specificity of m6A RNA methylation and its implication in cancer therapy

N6-methyladenosine (m6A) is the most abundant endogenous modification in eukaryotic RNAs. It plays important roles in various biological processes and diseases, including cancers. More and more studies have revealed that the deposition of m6A is specifically regulated in a context-dependent manner. Here, we review the diverse mechanisms that determine the topology of m6A along RNAs and the cell-type-specific m6A methylomes. The exon junction complex (EJC) as well as histone modifications play important roles in determining the topological distribution of m6A along nascent RNAs, while the transcription factors and RNA-binding proteins, which usually bind specific DNAs and RNAs in a cell-type-specific manner, largely account for the cell-type-specific m6A methylomes. Due to the lack of specificity of m6A writers and readers, there are still challenges to target the core m6A machinery for cancer therapies. Therefore, understanding the mechanisms underlying the specificity of m6A modifications in cancers would be important for future cancer therapies through m6A intervention.

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.

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

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

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

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

Liquid-liquid phase separation in diseases

Liquid-liquid phase separation (LLPS), an emerging biophysical phenomenon, can sequester molecules to implement physiological and pathological functions. LLPS implements the assembly of numerous membraneless chambers, including stress granules and P-bodies, containing RNA and protein. RNA-RNA and RNA-protein interactions play a critical role in LLPS. Scaffolding proteins, through multivalent interactions and external factors, support protein-RNA interaction networks to form condensates involved in a variety of diseases, particularly neurodegenerative diseases and cancer. Modulating LLPS phenomenon in multiple pathogenic proteins for the treatment of neurodegenerative diseases and cancer could present a promising direction, though recent advances in this area are limited. Here, we summarize in detail the complexity of LLPS in constructing signaling pathways and highlight the role of LLPS in neurodegenerative diseases and cancers. We also explore RNA modifications on LLPS to alter diseases progression because these modifications can influence LLPS of certain proteins or the formation of stress granules, and discuss the possibility of proper manipulation of LLPS process to restore cellular homeostasis or develop therapeutic drugs for the eradication of diseases. This review attempts to discuss potential therapeutic opportunities by elaborating on the connection between LLPS, RNA modification, and their roles in diseases.

Intracellular Fusobacterium nucleatum infection increases METTL3-mediated m6A methylation to promote the metastasis of esophageal squamous cell carcinoma

INTRODUCTION

The tumor-associated microbiota plays a vital role in cancer development. Accumulating evidence shows that Fusobacterium nucleatum (Fn) participates in the progression of multiple tumor types. However, the underlying mechanisms remain unclear.

OBJECTIVES

This study examined the expression of methyltransferase-like protein 3 (METTL3) during Fn infection and elucidated the function and pathway of Fn-induced m6A methylation in esophageal squamous cell carcinoma (ESCC).

METHODS

The abundance of Fn in patient tissues was determined by qPCR. Western blot, qRT-PCR, and immunohistochemistry were performed to measure METTL3 expression in cells and tissues. METTL3 function was evaluated in vitro by colony formation and cell migration assays. MeRIP-qPCR was performed to determine the relationship between METTL3 and c-Myc. In addition, the half-lives of genes that are downstream of METTL3 were determined with RNA stability assays.

RESULTS

Fn was enriched in hepatocellular carcinoma (HCC), breast cancer (BRCA), ESCC, and colorectal cancer (CRC) tumor tissues. METTL3 expression was positively associated with Fn abundance in ESCC tissues. Fn could survive and proliferation as well as increase METTL3 expression in ESCC, HCC, CRC, and BRCA cells. Moreover, METTL3 overexpression promoted ESCC cells proliferation, migration in vivo and in vitro. Mechanistically, Intracellular Fn infection increases METTL3 transcription. METTL3 promoted c-Myc mRNA methylation in the 3'-untranslated Region (3'-UTR) and enhanced its mRNA stability in a YTH N6-Methyladenosine RNA binding protein 1(YTHDF1)-dependent manner, which contributes to Fn induced ESCC proliferation and metastasis.

CONCLUSIONS

This study indicates that intracellular Fn infection promotes ESCC development and metastasis, and eradicating Fn infection may be a promising strategy for treating ESCC.

ZFHX3 acts as a tumor suppressor in prostate cancer by targeting FTO-mediated m6A demethylation

Zinc-finger homeobox 3 (ZFHX3, also known as ATBF1) suppresses prostatic tumorigenesis. ZFHX3 is frequently found to have numerous deletions in human prostate cancer (PCa). However, the underlying molecular function of ZFHX3 during prostatic tumorigenesis is not well understood. N6-methyladenosine (m6A) modification in RNA plays a critical role in the development of cancers; however, the relationship between ZFHX3 and m6A modification is largely unknown in PCa. In this study, we found that ZFHX3 knockdown decreased total m6A levels through enhancing the transcriptional activity of FTO in PCa cells. Importantly, FTO inhibition suppressed cell proliferation and rescued the promoting function of ZFHX3 knockdown on cell proliferation. In vivo, we verified that FTO was upregulated and ZFHX3 was decreased in PCa patients and that a high level of ZFHX3 is indispensable for low FTO expression and is correlated with better patient survival. Through transcriptome sequencing and MeRIP sequencing, we revealed that E2F2 and CDKN2C were the direct targets of FTO-mediated m6A modification and ZFXH3 was required for the regulation of FTO on E2F2 and CDKN2C expression. Unexpectedly, we uncovered that ZFHX3 expression was in return regulated by FTO in an m6A-dependent way. These findings establish a novel crosstalk mechanism between ZFHX3 and FTO in prostatic tumorigenesis.

Effects and mechanisms of N6-methyladenosine RNA methylation in environmental pollutant-induced carcinogenesis

Environmental pollution, including air pollution, plastic contamination, and heavy metal exposure, is a pressing global issue. This crisis contributes significantly to pollution-related diseases and is a critical risk factor for chronic health conditions, including cancer. Mounting evidence underscores the pivotal role of N6-methyladenosine (m6A) as a crucial regulatory mechanism in pathological processes and cancer progression. Governed by m6A writers, erasers, and readers, m6A orchestrates alterations in target gene expression, consequently playing a vital role in a spectrum of RNA processes, covering mRNA processing, translation, degradation, splicing, nuclear export, and folding. Thus, there is a growing need to pinpoint specific m6A-regulated targets in environmental pollutant-induced carcinogenesis, an emerging area of research in cancer prevention. This review consolidates the understanding of m6A modification in environmental pollutant-induced tumorigenesis, explicitly examining its implications in lung, skin, and bladder cancer. We also investigate the biological mechanisms that underlie carcinogenesis originating from pollution. Specific m6A methylation pathways, such as the HIF1A/METTL3/IGF2BP3/BIRC5 network, METTL3/YTHDF1-mediated m6A modification of IL 24, METTL3/YTHDF2 dynamically catalyzed m6A modification of AKT1, METTL3-mediated m6A-modified oxidative stress, METTL16-mediated m6A modification, site-specific ATG13 methylation-mediated autophagy, and the role of m6A in up-regulating ribosome biogenesis, all come into play in this intricate process. Furthermore, we discuss the direction regarding the interplay between pollutants and RNA metabolism, particularly in immune response, providing new information on RNA modifications for future exploration.

Role of microRNAs in tumor progression by regulation of kinesin motor proteins

Aberrant cell proliferation is one of the main characteristics of tumor cells that can be affected by many cellular processes and signaling pathways. Kinesin superfamily proteins (KIFs) are motor proteins that are involved in cytoplasmic transportations and chromosomal segregation during cell proliferation. Therefore, regulation of the KIF functions as vital factors in chromosomal stability is necessary to maintain normal cellular homeostasis and proliferation. KIF deregulations have been reported in various cancers. MicroRNAs (miRNAs) and signaling pathways are important regulators of KIF proteins. MiRNAs have key roles in regulation of the cell proliferation, migration, and apoptosis. In the present review, we discussed the role of miRNAs in tumor biology through the regulation of KIF proteins. It has been shown that miRNAs have mainly a tumor suppressor function via the KIF targeting. This review can be an effective step to introduce the miRNAs/KIFs axis as a probable therapeutic target in tumor cells.

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

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

Enhancing m6A modification of lncRNA through METTL3 and RBM15 to promote malignant progression in bladder cancer

Objective

Bladder cancer is one of the most prominent malignancies affecting the urinary tract, characterized by a poor prognosis. Our previous research has underscored the pivotal role of m6A methylation in the progression of bladder cancer. Nevertheless, the precise relationship between N6-methyladenosine (m6A) regulation of long non-coding RNA (lncRNA) and bladder cancer remains elusive.

Methods

This study harnessed sequencing data and clinical records from 408 bladder cancer patients in the TCGA database. Employing R software, we conducted bioinformatics analysis to establish an m6A-lncRNA co-expression network. Analyzing the differences between high and low-risk groups, particularly at the immunological level, and subsequently investigating the primary regulatory factors of these lncRNA, validating the findings through experiments, and exploring their specific cellular functions.

Results

We identified 50 m6A-related lncRNA with prognostic significance through univariate Cox regression analysis. In parallel, we employed a LASSO-Cox regression model to pinpoint 11 lncRNA and calculate risk scores for bladder cancer patients. Based on the median risk score, patients were categorized into low-risk and high-risk groups. The high-risk cohort exhibited notably lower survival rates than their low-risk counterparts. Further analysis pointed to RBM15 and METTL3 as potential master regulators of these m6A-lncRNA. Experimental findings also shed light on the upregulated expression of METTlL3 and RBM15 in bladder cancer, where they contributed to the malignant progression of tumors. The experimental findings demonstrated a significant upregulation of METTL3 and RBM15 in bladder cancer specimens, implicating their contributory role in the oncogenic progression. Knockdown of METTL3 and RBM15 resulted in a marked attenuation of tumor cell proliferation, invasion, and migration, which was concomitant with a downregulation in the cellular m6A methylation status. Moreover, these results revealed that RBM15 and METTL3 function in a synergistic capacity, positing their involvement in cancer promotion via the upregulation of m6A modifications in long non-coding RNAs. Additionally, this study successfully developed an N-methyl-N-nitrosourea (MNU)-induced rat model of in situ bladder carcinoma, confirming the elevated expression of RBM15 and METTL3, which paralleled the overexpression of m6A-related- lncRNAs observed in bladder cancer cell lines. This congruence underscores the potential utility of these molecular markers in in vivo models that mirror human malignancies.

Conclusion

This study not only offers novel molecular targets,but also enriches the research on m6A modification in bladder cancer, thereby facilitating its clinical translation.

LINC01614 is a promising diagnostic and prognostic marker in HNSC linked to the tumor microenvironment and oncogenic function

Background

Tumor initiation and metastasis influence tumor immune exclusion and immunosuppression. Long non-coding RNA (lncRNA) LINC01614 is associated with the prognosis and metastasis of several cancers. However, the relationship between LINC01614 and cancer immune infiltration and the biofunction of LINC01614 in head and neck squamous cell carcinoma (HNSC) remain unclear.

Methods

The Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) datasets were used to analyze the expression difference and diagnostic value of LINC01614 in normal and tumor tissues. The correlation of pan-cancer prognosis and tumor stage of LINC01614 was analyzed based on the TCGA database. The pan-cancer association of LINC01614 expression with the tumor microenvironment (TME) including immune infiltration, expression of immune-related genes, and genomic instability parameters, was analyzed using the Spearman correlation method. The correlation between LINC01614 and tumor stemness evaluation indicators, RNA methylation-related genes, and drug resistance was also analyzed. The functional analysis of LINC01614 was performed using the clusterProfiler R package. The protein-protein interaction (PPI) network and ceRNA network of LINC01614 co-expressed genes and miRNA were constructed and visualized by STRING and Cytoscape, respectively. Finally, the cell location and influence of LINC01614 on cell proliferation and metastasis of HNSC cell lines were evaluated using FISH, CCK-8, wound-healing assay, and transwell assay.

Results

LINC01614 was found to be overexpressed in 23 cancers and showed a highly sensitive prediction value in nine cancers (AUC >0.85). LINC01614 dysregulation was associated with tumor stage in 12 cancers and significantly influenced the survival outcomes of 26 cancer types, with only Lymphoid Neoplasm Diffuse Large B-cell Lymphoma (DLBC), uterine corpus endometrial carcinoma (UCEC), and bladder urothelial carcinoma (BLCA) showing a benign influence. LINC01614 was also associated with immune cell infiltration, tumor heterogeneity, cancer stemness, RNA methylation modification, and drug resistance. The potential biological function of LINC01614 was verified in HNSC, and it was found to play important roles in proliferation, immune infiltration, immunotherapy response, and metastasis of HNSC.

Conclusion

LINC01614 may serve as a cancer diagnosis and prognosis biomarker and an immunotherapy target for specific cancers.

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).

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.

Identification of m6A-related lncRNAs-based signature for predicting the prognosis of patients with skin cutaneous melanoma

BACKGROUND

Skin cutaneous melanoma (SKCM) is one of the fastest developing malignancies with strong aggressive ability and no proper curative treatments. Numerous studies illustrated the importance of N6-methyladenosine (m6A) RNA modification to tumorigenesis. The aim of this study was to identify novel prognostic signature by using m6A-related lncRNAs, thus to improve the survival for SKCM patients and guide SKCM therapy.

METHODS

We downloaded the Presentational Matrix data from The Cancer Genome Atlas (TCGA) and analyzed all the expressed lncRNAs among 468 SKCM samples. Pearson correlation analysis was performed to assess the correlations between lncRNAs and 29 m6A-related genes. Least absolute shrinkage and selection operator (LASSO), univariate and multivariate Cox regression analysis were performed to construct m6A-related lncRNAs prognostic signature (m6A-LPS). The accuracy and prognostic value of this signature were validated by using receiver operating characteristic (ROC) curves, Kaplan-Meier (K-M) survival analysis, univariate COX or multivariate COX analyses. After calculating risk scores, patients were divided into low- and high-risk subgroups by the median value of risk scores.

RESULTS

A total of 2973 lncRNAs were found expressed among SKCM tissues. Prognostic analysis showed that 98 lncRNAs had a significant effect on the survival of SKCM patients. The m6A-LPS was validated using K-M and ROC analysis and the predictive accuracy of the risk score was also high according to the AUC of the ROC curve in training and testing sets. A nomogram based on tumor stage, gender and risk score that had a strong ability to forecast the 1-, 2-, 3-, 5-year OS of SKCM patients confirmed by calibrations. Enrichment analysis indicated that malignancy-associated biological processes and pathways were more common in the high-risk subgroup.

CONCLUSION

Collectively, m6A-related lncRNAs exert as potential biomarkers for prognostic stratification of SKCM patients and may assist clinicians achieving individualized treatment for SKCM.

G3BP1 and SLU7 Jointly Promote Immune Evasion by Downregulating MHC-I via PI3K/Akt Activation in Bladder Cancer

Immune checkpoint inhibitors (ICIs) show promise as second-line treatment for advanced bladder cancer (BLCA); however, their responsiveness is limited by the immune evasion mechanisms in tumor cells. This study conduct a Cox regression analysis to screen mRNA-binding proteins and reveals an association between Ras GTPase-activating protein-binding protein 1 (G3BP1) and diminished effectiveness of ICI therapy in patients with advanced BLCA. Subsequent investigation demonstrates that G3BP1 enhances immune evasion in BLCA cells by downregulating major histocompatibility complex class I (MHC-I) through phosphoinositide 3-kinase (PI3K)/Akt signaling activation. Mechanistically, G3BP1 interacts with splicing factor synergistic lethal with U5 snRNA 7 (SLU7) to form a complex with poly(A)-binding protein cytoplasmic 1 and eukaryotic translation initiation factor 4 gamma 1. This complex stabilizes the closed-loop structure of the mRNAs of class IA PI3Ks and consequently facilitates their translation and stabilization, thereby activating PI3K/Akt signaling to downregulate MHC-I. Consistently, targeting G3BP1 with epigallocatechin gallate (EGCG) impedes immune evasion and sensitizes BLCA cells to anti-programmed cell death (PD)-1 antibodies in mice. Thus, G3BP1 and SLU7 collaboratively contribute to immune evasion in BLCA, indicating that EGCG is a precision therapeutic agent to enhance the effectiveness of anti-PD-1 therapy.

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

INTRODUCTION

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Regulatory effects of natural products on N6-methyladenosine modification: A novel therapeutic strategy for cancer

N6-methyladenosine (m6A) is considered to be the most common and abundant epigenetics modification in messenger RNA (mRNA) and noncoding RNA. Abnormal modification of m6A is closely related to the occurrence, development, progression, and prognosis of cancer. m6A regulators have been identified as novel targets for anticancer drugs. Natural products, a rich source of traditional anticancer drugs, have been utilized for the development of m6A-targeting drugs. Here, we review the key role of m6A modification in cancer progression and explore the prospects and structural modification mechanisms of natural products as potential drugs targeting m6A modification for cancer treatment.

Identification of MYC intron 2 regions that modulate expression

MYC pre-mRNA is spliced with high fidelity to produce the transcription factor known to regulate cellular differentiation, proliferation, apoptosis, and alternative splicing. The mechanisms underpinning the pre-mRNA splicing of MYC, however, remain mostly unexplored. In this study, we examined the interaction of heterogeneous nuclear ribonucleoprotein C (HNRNPC) with MYC intron 2. Building off published eCLIP studies, we confirmed this interaction with poly(U) regions in intron 2 of MYC and found that full binding is correlated with optimal protein production. The interaction appears to be compensatory, as mutational disruption of all three poly(U) regions was required to reduce both HNRNPC binding capacity and fidelity of either splicing or translation. Poly(U) sequences in MYC intron 2 were relatively conserved across sequences from several different species. Lastly, we identified a short sequence just upstream of an HNRNPC binding region that when removed enhances MYC translation.

METTL3 facilitates renal cell carcinoma progression by PLOD2 m6A-methylation under prolonged hypoxia

N6-methyladenosine (m6A) is the most prevalent reversible modification in eukaryotic mRNA, and it plays a critical role in tumor progression. The purpose of this study was to investigate the function and regulatory mechanisms of the methyltransferase METTL3 in renal cell carcinoma (RCC). METTL3 expression was upregulated and predicted a poor prognosis in patients with advanced RCC. METTL3 facilitated the proliferation, migration, and invasion of RCC cells, depending on its methylase activity. METTL3 positively regulated the expression of PLOD2, and both genes were triggered under prolonged hypoxia. Mechanistically, hypoxia-induced the binding of HIF-1α to the METTL3 promoter, which enhanced its transcriptional activity. METTL3-mediated m6A modifications of PLOD2 mRNA at 3'UTR region, promoting the translation of PLOD2 protein. Furthermore, silencing METTL3 impaired RCC progression in vitro. In vivo, administration of highly potent and selective METTL3 inhibitor STM2457 showed anti-tumor effects, whereas AAV9-mediated re-transduction of PLOD2 largely abolished the above phenomenon in a subcutaneous mouse model. These findings reveal that hypoxia and HIF-driven METTL3 transcription promote RCC progression by increasing PLOD2 expression in an m6A-dependent manner, suggesting that METTL3 may serve as a novel pharmaceutical intervention for RCC.

PIGT promotes cell growth, glycolysis, and metastasis in bladder cancer by modulating GLUT1 glycosylation and membrane trafficking

BACKGROUND

Bladder cancer is very common worldwide. PIGT is a subunit of the glycosylphosphatidylinositol transamidase which involves in tumorigenesis and invasiveness. m6A modification of mRNA has been linked to cell proliferation, tumor progression and other biological events. However, how PIGT is regulated and what is the function of PIGT in bladder cancer remains to be elucidated.

METHODS

PIGT was silenced or overexpressed to study its role in regulating bladder cancer. Cell proliferation and invasion were examined with the Cell Counting Kit-8, colony formation and Transwell assay, respectively. Cellular oxygen consumption rates or extracellular acidification rates were detected by a XF24 Analyzer. Quantitative RT-PCR and immunoblots were performed to detect mRNA and protein levels.

RESULTS

PIGT was overexpressed in bladder cancer. Silencing PIGT inhibited cell proliferation, oxidative phosphorylation, and glycolysis. Overexpressing PIGT promoted cell proliferation, oxidative phosphorylation, glycolysis in vitro and tumor metastasis in vivo by activating glucose transporter 1 (GLUT1). PIGT also promoted GLUT1 glycosylation and membrane trafficking. Wilms' tumor 1-associated protein (WTAP) mediated PIGT m6A modification, and m6A reader, insulin-like growth factor 2 mRNA-binding protein (IGF2BP2), binds to the methylated PIGT to promote the stability of PIGT, leading to up-regulation of PIGT.

CONCLUSION

WTAP mediates PIGT m6A modification to increase the stability of PIGT via the IGF2BP2, which enhances cell proliferation, glycolysis, and metastasis in bladder cancer by modulating GLUT1 glycosylation and membrane trafficking.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Emerging roles and mechanism of m6A methylation in rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifaceted autoimmune disease characterized by systemic inflammation, affecting both articular and extra-articular structures. This condition results in inflammation of joints and synovial membranes, accompanied by the development of systemic comorbidities. Despite extensive research, the precise pathogenic mechanisms responsible for RA have yet to be completely understood. RNA methylation, a burgeoning epigenetic alteration, assumes a pivotal function in the regulation of a myriad of biological phenomena, encompassing immunity, DNA damage response, tumorigenesis, metastasis, stem cell renewal, adipocyte differentiation, circadian rhythms, cellular development and differentiation, and cell division. The N6-methyladenosine (m6A) modification is the most prevalent among the various RNA modifications found in mammalian mRNA. Recent studies have provided evidence of the significant role played by m6A modification in the pathophysiological progression of RA. This review aims to provide a comprehensive analysis of the progress made in research focused on m6A modification in the context of RA, consolidate the underlying mechanisms involved in m6A modification during the initiation of RA and discuss the potential of targeting m6A modification as a viable therapeutic approach for RA.

The Biological Significance of AFF4: Promoting Transcription Elongation, Osteogenic Differentiation and Tumor Progression

As a member of the AF4/FMR2 (AFF) family, AFF4 is a scaffold protein in the superelongation complex (SEC). In this mini-view, we discuss the role of AFF4 as a transcription elongation factor that mediates HIV activation and replication and stem cell osteogenic differentiation. AFF4 also promotes the progression of head and neck squamous cell carcinoma, leukemia, breast cancer, bladder cancer and other malignant tumors. The biological function of AFF4 is largely achieved through SEC assembly, regulates SRY-box transcription factor 2 (SOX2), MYC, estrogen receptor alpha (ESR1), inhibitor of differentiation 1 (ID1), c-Jun and noncanonical nuclear factor-κB (NF-κB) transcription and combines with fusion in sarcoma (FUS), unique regulatory cyclins (CycT1), or mixed lineage leukemia (MLL). We explore the prospects of using AFF4 as a therapeutic in Acquired immunodeficiency syndrome (AIDS) and malignant tumors and its potential as a stemness regulator.

METTL3 regulates the proliferation, metastasis and EMT progression of bladder cancer through P3H4

Bladder cancer, the most common malignant tumor in the urinary system, exhibits significantly up-regulated expression of P3H4, which is associated with pathological factors. The objective of this study was to elucidate the underlying mechanism of P3H4 in bladder cancer. Initially, we analyzed P3H4 gene expression using the TCGA database and evaluated P3H4 levels in clinical samples and various bladder cell lines. P3H4 was found to be markedly overexpressed in bladder cancer samples. Subsequently, bladder cancer cells were transfected with shRNA targeting P3H4 (sh-P3H4), sh-METTL3, and P3H4 overexpression vectors (P3H4 OE). Viability, migration, and invasion of bladder cancer cells were assessed using CCK-8, wound healing, and transwell assays. Western blot analysis was performed to determine the levels of EMT-associated proteins, while RNA stability assays determined the half-life of P3H4. Knockdown of P3H4 resulted in inhibition of bladder cancer cell proliferation, migration, invasion, and EMT progression. Mechanistically, METTL3 was found to regulate the mRNA stability of P3H4 in bladder cancer. Moreover, overexpression of P3H4 reversed the inhibitory effects of METTL3 knockdown on bladder cancer cell behaviors. Stable cell lines were established by infecting EJ cells with lentiviral vectors containing sh-METTL3 or P3H4 OE. These cells were then implanted into the skin of BALB/c nude mice, and IHC analysis was used to analyze the expression levels of EMT-associated proteins. In vivo studies demonstrated that inhibition of METTL3 suppressed bladder cancer growth and EMT through P3H4. In conclusion, our findings suggest that METTL3 regulates the proliferation, metastasis, and EMT progression of bladder cancer through P3H4, highlighting its potential as a therapeutic target.

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

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

Multiple Genomic Alterations, Including a Novel AFF4::IRF1 Fusion Gene, in a Treatment-Refractory Blastic Plasmacytoid Dendritic-Cell Neoplasm: A Case Report and Literature Review

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with an aggressive clinical course and poor prognosis. The genetic abnormalities in BPDCN are heterogeneous; therefore, its molecular pathogenesis and the prognostic importance of genomic alterations associated with the disease are not well defined. Here we report a case of BPDCN with a novel AFF4::IRF1 fusion predicted to lead to a loss-of-function of the IRF1 tumor suppressor, somatic mutations of ASXL1, TET2, and MYD88, as well as multiple intrachromosomal deletions. The patient showed resistance to Tagraxofusp and Venetoclax, and he died about 16 months after diagnosis. Considering the predicted effect of the AFF4::IRF1 fusion on IRF1's antitumor effects and immune regulation, and the possibility of its relevance to the aggressive course observed in this case, we propose further evaluation of the clinical significance of this fusion in BPDCN in future cooperative group studies and the consideration of therapeutic strategies aimed at restoring IRF1-dependent antineoplastic effects in such cases.

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.

Targeting AKT induced Ferroptosis through FTO/YTHDF2-dependent GPX4 m6A methylation up-regulating and degradating in colorectal cancer

Ferroptosis is a new type of iron-dependent programmed cell death induced by lipid peroxidation. However, the underlying mechanisms and function in tumor therapy still remain undisclosed especially in post-transcription regulation. Here, we found that targeting AKT significantly induced GPX4 dependent ferroptosis and suppressed colorectal cancer growth both in vitro and in vivo. During this process, demethylase FTO was downregulated, which increased the m6A methylation level of GPX4, subsequently recognized by YTHDF2 and degraded. Prediction results showed that there are three potential methylated sites (193/647/766), and 193 site was identified as the right one, which was demethylated by FTO and read by YTHDF2. In parallel, AKT inhibition caused the accumulation of ROS which had a negative feedback on GPX4 expression. In addition, protective autophagy was initiated by MK2206 stimulation, while blocking autophagy further increased ferroptosis and markedly enhanced the anti-tumor activity of MK2206. In a word, inhibiting AKT activated ferroptosis through FTO/YTHDF2/GPX4 axis to suppress colon cancer progression, which raised FTO/GPX4 as potential biomarkers and targets in colorectal cancer therapy.

BRD4 as a potential target for human papillomaviruses associated cancer

Around 99% of cervical cancer and 5%-10% of human cancer are associated with human papillomaviruses (HPV). Notably, the life-cycle of HPV begins by low-level infection of the basal cells of the stratified epithelium, where the viral genomes are replicated and passed on to the daughter proliferating basal cells. The production of new viral particles remains restricted to eventually differentiated cells. HPVs support their persistent infectious cycle by hijacking pivotal pathways and cellular processes. Bromodomain-containing protein 4 (BRD4) is one of the essential cellular factors involved in multiple stages of viral transcription and replication. In this review, we demonstrate the role of BRD4 in the multiple stages of HPV infectious cycle. Also, we provide an overview of the intense research about the cellular functions of BRD4, the mechanism of action of bromodomain and extra terminal inhibitors, and how it could lead to the development of antiviral/anticancer therapies.

m6A-Mediated Biogenesis of circDDIT4 Inhibits Prostate Cancer Progression by Sequestrating ELAVL1/HuR

The pathologic significance of the circular RNA DDIT4 (circDDIT4), which is formed by backsplicing at the 3'-untranslated region (UTR) with a 5' splice acceptor site in exon 2 of linear DDIT4 mRNA, has yet to be determined. Our study found that circDDIT4 is downregulated in prostate cancer and functions as a tumor suppressor during prostate cancer progression. By competitively binding to ELAV-like RNA binding protein 1 (ELAVL1/HuR) through its 3'-UTR, circDDIT4 acts as a protein sponge to decrease the expression of prostate cancer-overexpressed anoctamin 7 (ANO7). This promotes prostate cancer cell apoptosis while inhibiting cell proliferation and metastasis. Furthermore, we discovered that N6-methyladenosine (m6A) modification facilitates the biogenesis of circDDIT4. The methyltransferase complex consisting of WTAP/METTL3/METTL14 increases the level of circDDIT4, while the RNA demethylase FTO decreases it.

IMPLICATIONS

These findings suggest that abnormal cotranscriptional modification of m6A promotes prostate cancer initiation and progression via a circular RNA-protein-cell signaling network.

Induced pluripotent stem cell-derived extracellular vesicles overexpressing SFPQ protect retinal Müller cells against hypoxia-induced injury

Splicing factor proline/glutamine-rich (SFPQ) is expressed in induced pluripotent stem cells (iPSCs), which are reported to orchestrate hypoxic injury responses and release extracellular vesicles (EVs). Therefore, this study sought to explore the role of iPSC-derived EVs carrying SFPQ in hypoxia-induced injury to retinal Müller cells. We induced oxygen-glucose deprivation/reoxygenation (OGD/R) in Müller cells. SFPQ was overexpressed or knocked down in iPSCs, from which EVs were extracted. Müller cells were co-cultured with EVs, and the results indicated that SFPQ protein was transferred into retinal Müller cells by iPSC-derived EVs. We identified an interaction of SFPQ with HDAC1 in retinal Müller cells. Specifically, SFPQ recruited HDAC1 to downregulate HIF-2α by regulating its acetylation. The in vitro studies suggested that iPSC-derived EVs, SFPQ or HDAC1 overexpression, or HIF-2α silencing diminished cell injury and apoptosis but elevated proliferation in retinal Müller cells. The in vivo studies indicated that iPSC-derived EVs containing SFPQ curtailed apoptosis of retinal Müller cells, thus alleviating retinal ischemia/reperfusion (I/R) injury of rat model. Taken together, iPSC-derived EVs containing SFPQ upregulated HDAC1 to attenuate OGD/R-induced Müller cell injury via downregulation of HIF-2α.

New insights into the regulation of METTL3 and its role in tumors

As one of the most abundant epigenetic modifications in RNA, N6-methyladenosine (m6A) affects RNA transcription, splicing, stability, and posttranscriptional translation. Methyltransferase-like 3 (METTL3), a key component of the m6A methyltransferase complex, dynamically regulates target genes expression through m6A modification. METTL3 has been found to play a critical role in tumorigenesis, tumor growth, metastasis, metabolic reprogramming, immune cell infiltration, and tumor drug resistance. As a result, the development of targeted drugs against METTL3 is becoming increasingly popular. This review systematically summarizes the factors that regulate METTL3 expression and explores the specific mechanisms by which METTL3 affects multiple tumor biological behaviors. We aim to provide fundamental support for tumor diagnosis and treatment, at the same time, to offer new ideas for the development of tumor-targeting drugs.

METTL3-mediated m6A methylation regulates ovarian cancer progression by recruiting myeloid-derived suppressor cells

BACKGROUND

Ovarian cancer (OC) typically develops an immunosuppressive microenvironment by funtional changes of host immune cells. Dysregulated m6A level is associated with cancer progression via the intrinsic oncogenic pathways. However, the role of m6A in regulating host immune cell function during anti-tumor immunity needs comprehensive analysis. This study aimed to investigate the role of METTL3, a catalytic subunit of the methyltransferase complex, in regulating host immune cell response against OC.

METHODS

In this study, myeloid-specific Mettl3 gene knockout (Mettl3-cKO) mice were bred using the Cre-LoxP system. Intraperitoneally injection of ID8 cells was used as a syngeneic OC model. Furthermore, the compositions of immune cell populations were analyzed by flow cytometry and single-cell sequencing. Moreover, chemokines and cytokines secretion were assessed using ELISA. Lastly, the role of METTL3 in regulating IL-1β secretion and inflammasome activation in bone marrow-derived macrophages cocultured with ID8 cells was specified by ELISA and immunoblotting.

RESULTS

It was revealed that OC cell growth was enhanced in Mettl3-cKO mice. Furthermore, a shift of decreased M1 to increased M2 macrophage polarization was observed during OC progression. Moreover, Mettl3 depletion in myeloid lineage cells increased secretion of CCL2 and CXCL2 in peritoneal lavage fluild. Interestingly, Mettl3 deficiency enhanced IL-1β secretion induced by viable ID8 cells independent of inflammasome activation and cell death. Therefore, OC cells in tumor-bearing mice trigger a slight inflammatory response with a low-to-moderate secretion of pro-inflammatory cytokines and chemokines.

CONCLUSION

This study provides new insights into METTL3-mediated m6A methylation, which regulates host immune response against OC.

The crucial roles of m6A RNA modifications in cutaneous cancers: Implications in pathogenesis, metastasis, drug resistance, and targeted therapies

N6-methyladenosine (m6A) is the most abundant internal modification on RNA. It is a dynamical and reversible process, which is regulated by m6A methyltransferase and m6A demethylase. The m6A modified RNA can be specifically recognized by the m6A reader, leading to RNA splicing, maturation, degradation or translation. The abnormality of m6A RNA modification is closely related to a variety of biological processes, especially the occurrence and development of tumors. Recent studies have shown that m6A RNA modification is involved in the pathogenesis of skin cancers. However, the precise molecular mechanisms of m6A-mediated cutaneous tumorigenesis have not been fully elucidated. Therefore, this review will summarize the biological characteristics of m6A modification, its regulatory role and mechanism in skin cancers, and the recent research progress of m6A-related molecular drugs, aiming to provide new ideas for clinical diagnosis and targeted therapy of cutaneous cancers.

BRD4 and MYC: power couple in transcription and disease

The MYC proto-oncogene and BRD4, a BET family protein, are two cardinal proteins that have a broad influence in cell biology and disease. Both proteins are expressed ubiquitously in mammalian cells and play central roles in controlling growth, development, stress responses and metabolic function. As chromatin and transcriptional regulators, they play a critical role in regulating the expression of a burgeoning array of genes, maintaining chromatin architecture and genome stability. Consequently, impairment of their function or regulation leads to many diseases, with cancer being the most predominant. Interestingly, accumulating evidence indicates that regulation of the expression and functions of MYC are tightly intertwined with BRD4 at both transcriptional and post-transcriptional levels. Here, we review the mechanisms by which MYC and BRD4 are regulated, their functions in governing various molecular mechanisms and the consequences of their dysregulation that lead to disease. We present a perspective of how the regulatory mechanisms for the two proteins could be entwined at multiple points in a BRD4-MYC nexus that leads to the modulation of their functions and disease upon dysregulation.

METTL3 facilitates multiple myeloma tumorigenesis by enhancing YY1 stability and pri-microRNA-27 maturation in m6A-dependent manner

Multiple myeloma (MM) is a pernicious plasma cell disorder and has a poor prognosis. N6-methyladenosine (m6A) is an abundant epigenetic RNA modification and is important in cancer progression. Nevertheless, the function of m6A and its regulator METTL3 in MM are rarely reported. Here, we identified the m6A "writers", METTL3, was enhanced in MM and found that Yin Yang 1 (YY1) and primary-miR-27a-3p were the potential target for METTL3. METTL3 promoted primary-miR-27a-3p maturation and YY1 mRNA stability in an m6A manner. YY1 also was found to facilitate miR-27a-3p transcription. METTL3 affected the growth, apoptosis, and stemness of MM cells through accelerating the stability of YY1 mRNA and the maturation of primary-miR-27a-3p in vitro and in vivo. Our results reveal the key function of the METTL3/YY1/miR-27a-3p axis in MM and may provide fresh insights into MM therapy.

The current landscape of m6A modification in urological cancers

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

Dissecting the effects of METTL3 on alternative splicing in prostate cancer

Although the role of METTL3 has been extensively studied in many cancers, its role in isoform switching in prostate cancer (PCa) has been poorly explored. To investigate its role, we applied standard RNA-sequencing and long-read direct RNA-sequencing from Oxford Nanopore to examine how METTL3 affects alternative splicing (AS) in two PCa cell lines. By dissecting genome-wide METTL3-regulated AS events, we noted that two PCa cell lines (representing two different PCa subtypes, androgen-sensitive or resistant) behave differently in exon skipping and intron retention events following METTL3 depletion, suggesting AS heterogeneity in PCa. Moreover, we revealed that METTL3-regulated AS is dependent on N6-methyladenosine (m6A) and distinct splicing factors. Analysis of the AS landscape also revealed cell type specific AS signatures for some genes (e.g., MKNK2) involved in key functions in PCa tumorigenesis. Finally, we also validated the clinical relevance of MKNK2 AS events in PCa patients and pointed to the possible regulatory mechanism related to m6A in the exon14a/b region and SRSF1. Overall, we characterize the role of METTL3 in regulating PCa-associated AS programs, expand the role of METTL3 in tumorigenesis, and suggest that MKNK2 AS events may serve as a new potential prognostic biomarker.