WTAP facilitates progression of hepatocellular carcinoma via m6A-HuR-dependent epigenetic silencing of ETS1

METTL3-Mediated ADAMTS9 Suppression Facilitates Angiogenesis and Carcinogenesis in Gastric Cancer

The role of methyltransferase-like 3 (METTL3), which participates in catalyzing N-methyladenosine (m6A) RNA modification, in gastric cancer (GC) is unclear. Here, we found that METTL3 was overexpressed in human GC. Functionally, we verified that METTL3 promoted tumor cell proliferation and angiogenesis through a series of phenotypic experiments. Subsequently, ADAMTS9 was identified as the downstream effector of METTL3 in GC, which could be degraded by the YTHDF2-dependent pathway. Finally, the data suggested that METTL3 might facilitate GC progression through the ADAMTS9-mediated PI3K/AKT pathway. Our study unveiled the fundamental mechanisms of METTL3 in GC progression. The clinical value of METTL3 in GC deserves further exploration.

Identification of m6A-Related lncRNA to Predict the Prognosis of Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. In the past decades, HCC treatment has achieved great progress; however, the overall prognosis remains poor. Therefore, it is the need of the hour to identify new prognostic biomarkers which can advance our understanding related to the underlying molecular mechanism of adverse prognosis and apply them to clinical work in prognosis prediction. In the present study, data of 576 HCC patients and 292 normal control cases from TCGA and ICGC databases were enrolled to our bioinformatic analysis. SNHG1 and SNHG3 were identified as overlapping genes in TCGA and ICGC databases using Pearson correlation analysis and univariate Cox regression analysis. Further, we used the median of the SNHG1 and SNHG3 expression values as the cutoff values to define the HCC patient groups with high or low expression level. The subsequent analysis revealed that abnormal high expression of SNHG1 or SNHG3 affected the immune infiltration patterns and the crosstalk among immune cells. Moreover, high expression of SNHG1 or SNHG3 resulted in drug resistant to AKT inhibitor VII, bexarotene, bicalutamide, dasatinib, erlotinib, and gefitinib. In addition, lower tumor neoantigen burden was observed in high SNHG1 or SNHG3 group. Further, we found significant relation between the aberrant upregulation of SNHG1 and SNHG3 in tumor grade and stage. We established a nomogram to systematically predict the 5- and 8-year overall survival of liver cancer patients with good accuracy. Finally, the in vitro assays suggest that SNHG1 and SNHG3 promote the proliferative, migratory, and invasive abilities of HCC cells.

The emerging roles of N6-methyladenosine (m6A)-modified long non-coding RNAs in human cancers

N⁶-methyladenosine (m⁶A) epitranscriptional modifications widely exist in RNA, which play critical roles in RNA metabolism and biogenesis processes. Long non-coding RNAs (lncRNAs) are class of non-coding RNAs longer than 200 nucleotides without protein-coding ability. LncRNAs participate in a large number of vital biological progressions. With the great improvement of molecular biology, m⁶A and lncRNAs are attracting more attention from researchers and scholars. In this review, we overview the current status of m⁶A and lncRNAs based on the latest research, and propose some viewpoints for future research perspectives.

Single-cell N6-methyladenosine regulator patterns guide intercellular communication of tumor microenvironment that contribute to colorectal cancer progression and immunotherapy

BACKGROUND

N6-methyladenosine (m⁶A) RNA methylation plays a critical role in key genetic events for various cancers; yet, how m⁶A functions within the tumor microenvironment (TME) remains to be elucidated.

METHODS

A total of 65,362 single cells from single-cell RNA-seq data derived from 33 CRC tumor samples were analyzed by nonnegative matrix factorization (NMF) for 23 m⁶A RNA methylation regulators. CRC and Immunotherapy cohorts from public repository were used to determine the prognosis and immune response of TME clusters.

RESULTS

The fibroblasts, macrophages, T and B cells were respectively grouped into 4 to 5 subclusters and then classified according to various biological processes and different marker genes. Furthermore, it revealed that the m⁶A RNA methylation regulators might be significantly related to the clinical and biological features of CRC, as well as the pseudotime trajectories of main TME cell types. Bulk-seq analysis suggested that these m⁶A-mediated TME cell subclusters had significant prognostic value for CRC patients and distinguished immune response for patients who underwent ICB therapy, especially for the CAFs and macrophages. Notably, CellChat analysis revealed that RNA m⁶A methylation-associated cell subtypes of TME cells manifested diverse and extensive interaction with tumor epithelial cells. Further analysis showed that ligand-receptor pairs, including MIF -  (CD74 + CXCR4), MIF -  (CD74 + CD44), MDK-NCL and LGALS9 - CD45, etc. mediated the communication between m⁶A associated subtypes of TME cells and tumor epithelial cells.

CONCLUSIONS

Taken together, our study firstly revealed the m⁶A methylation mediated intercellular communication of the tumor microenvironment in the regulation of tumor growth and antitumor immunomodulatory processes.

The Role of N6-Methyladenosine in the Promotion of Hepatoblastoma: A Critical Review

Simple Summary

Hepatoblastoma is the most common malignant pediatric tumor of the liver. Unlike hepatocellular carcinoma (HCC) which has been associated with hepatitis B virus infection or cirrhosis, the etiology of hepatoblastoma remains vague. Genetic syndromes, including familial adenomatous polyposis (FAP), Beckwith-Wiedemann syndrome (BWS), and trisomy 18 syndrome, have been associated with hepatoblastoma. BWS is an overgrowth syndrome which exhibits an alteration of genomic imprinting on chromosome 11p15.5. N⁶-Methyladenosine (M⁶A) is an RNA modification with rampant involvement in the metabolism of cells and malignant diseases. It has been observed to impact the development of various cancers via its governance of gene expression. Here, we explore the role of m⁶A and its genetic associates in promoting HB, and the impact this may have on our future management of the disease.

Abstract

Hepatoblastoma (HB) is a rare primary malignancy of the developing fetal liver. Its course is profoundly influenced by genetics, in the context of sporadic mutation or genetic syndromes. Conventionally, subtypes of HB are histologically determined based on the tissue type that is recapitulated by the tumor and the direction of its differentiation. This classification is being reevaluated based on advances on molecular pathology. The therapeutic approach comprises surgical intervention, chemotherapy (in a neoadjuvant or post-operative capacity), and in some cases, liver transplantation. Although diagnostic modalities and treatment options are evolving, some patients experience complications, including relapse, metastatic spread, and suboptimal response to chemotherapy. As yet, there is no consistent framework with which such outcomes can be predicted. N⁶-methyladenosine (m⁶A) is an RNA modification with rampant involvement in the normal processing of cell metabolism and neoplasia. It has been observed to impact the development of a variety of cancers via its governance of gene expression. M⁶A-associated genes appear prominently in HB. Literature data seem to underscore the role of m⁶A in promotion and clinical course of HB. Illuminating the pathogenetic mechanisms that drive HB are promising additions to the understanding of the clinically aggressive tumor behavior, given its potential to predict disease course and response to therapy. Implicated genes may also act as targets to facilitate the evolving personalized cancer therapy. Here, we explore the role of m⁶A and its genetic associates in the promotion of HB, and the impact this may have on the management of this neoplastic disease.

Role of main RNA modifications in cancer: N6-methyladenosine, 5-methylcytosine, and pseudouridine

Cancer is one of the major diseases threatening human life and health worldwide. Epigenetic modification refers to heritable changes in the genetic material without any changes in the nucleic acid sequence and results in heritable phenotypic changes. Epigenetic modifications regulate many biological processes, such as growth, aging, and various diseases, including cancer. With the advancement of next-generation sequencing technology, the role of RNA modifications in cancer progression has become increasingly prominent and is a hot spot in scientific research. This review studied several common RNA modifications, such as N⁶-methyladenosine, 5-methylcytosine, and pseudouridine. The deposition and roles of these modifications in coding and noncoding RNAs are summarized in detail. Based on the RNA modification background, this review summarized the expression, function, and underlying molecular mechanism of these modifications and their regulators in cancer and further discussed the role of some existing small-molecule inhibitors. More in-depth studies on RNA modification and cancer are needed to broaden the understanding of epigenetics and cancer diagnosis, treatment, and prognosis.

In the Tumor Microenvironment, ETS1 Is an Oncogenic Immune Protein: An Integrative Pancancer Analysis

Background

Previous research suggested that ETS1 (ETS proto-oncogene 1, transcription factor) could be useful for cancer immunotherapy. The processes underlying its therapeutic potential, on the other hand, have yet to be thoroughly investigated. The purpose of this study was to look into the relationship between ETS1 expression and immunity.

Methods

TCGA and GEO provide raw data on 33 different cancers as well as GSE67501, GSE78220, and IMvigor210. In addition, we looked at ETS1's genetic changes, expression patterns, and survival studies. The linkages between ETS1 and TME, as well as its association with immunological processes/elements and the major histocompatibility complex, were explored to effectively understand the role of ETS1 in cancer immunotherapy. Three distinct immunotherapeutic cohorts were employed to examine the relationship between ETS1 and immunotherapeutic response.

Results

ETS1 expression was shown to be high in tumor tissue. ETS1 overexpression is linked to a worse clinical outcome in individuals with overall survival. Immune cell infiltration, immunological modulators, and immunotherapeutic signs are all linked to ETS1. Overexpression of ETS1 is linked to immune-related pathways. However, no statistically significant link was found between ETS1 and immunotherapeutic response.

Conclusions

ETS1 may be a reliable biomarker for tumor prognosis and a viable prospective therapeutic target for human cancer immunotherapy (e.g., KIRP, MESO, BLCA, KIRC, and THYM).

Inhibition of METTL3 attenuates renal injury and inflammation by alleviating TAB3 m6A modifications via IGF2BP2-dependent mechanisms

The role of N⁶-methyladenosine (m6A) modifications in renal diseases is largely unknown. Here, we characterized the role of N⁶-adenosine-methyltransferase-like 3 (METTL3), whose expression is elevated in renal tubules in different acute kidney injury (AKI) models as well as in human biopsies and cultured tubular epithelial cells (TECs). METTL3 silencing alleviated renal inflammation and programmed cell death in TECs in response to stimulation by tumor necrosis factor-α (TNF-α), cisplatin, and lipopolysaccharide (LPS), whereas METTL3 overexpression had the opposite effects. Conditional knockout of METTL3 from mouse kidneys attenuated cisplatin- and ischemic/reperfusion (I/R)-induced renal dysfunction, injury, and inflammation. Moreover, TAB3 [TGF-β-activated kinase 1 (MAP3K7) binding protein 3] was identified as a target of METTL3 by m6A methylated RNA immunoprecipitation sequencing and RNA sequencing. The stability of TAB3 was increased through binding of IGF2BP2 (insulin-like growth factor 2 binding protein 2) to its m6A-modified stop codon regions. The proinflammatory effects of TAB3 were then explored both in vitro and in vivo. Adeno-associated virus 9 (AAV9)-mediated METTL3 silencing attenuated renal injury and inflammation in cisplatin- and LPS-induced AKI mouse models. We further identified Cpd-564 as a METTL3 inhibitor that had better protective effects against cisplatin- and ischemia/reperfusion-induced renal injury and inflammation than S-adenosyl-l-homocysteine, a previously identified METTL3 inhibitor. Collectively, METTL3 promoted m6A modifications of TAB3 and enhanced its stability via IGF2BP2-dependent mechanisms. Both genetic and pharmacological inhibition of METTL3 attenuated renal injury and inflammation, suggesting that the METTL3/TAB3 axis is a potential target for treatment of AKI.

WTAP Is Correlated With Unfavorable Prognosis, Tumor Cell Proliferation, and Immune Infiltration in Hepatocellular Carcinoma

WTAP is involved in various pathological and physiological processes, but its function in hepatocellular carcinoma (HCC) remains elusive. In this study, we investigated the role of WTAP in HCC. Firstly, the mRNA and protein of WTAP were expressed highly in HCC tissue, which reflected clinicopathological characteristics of HCC patients. Then, an interactive analysis of genetic profiles and Kaplan–Meier curves was performed to show that WTAP was an independent predictor of survival of HCC patients. Meanwhile, genes co-expressed with WTAP, potential protein–protein interactions, related signaling pathways, and immune cell infiltration were identified. It was found that high WTAP expression correlated with enhanced interactions between cytokines and their receptors, cell cycle, and chemokine signaling pathways, as well as increased immune cell infiltration. At last, WTAP knockdown experiments in vitro indicate that the WTAP silencing inhibited HCC proliferation and aggressiveness. We conclude that WTAP may be a novel biomarker for prognosis and a therapeutic target for HCC.

Long noncoding RNA lnc-H2AFV-1 promotes cell growth by regulating aberrant m6A RNA modification in HNSCC

Head and neck squamous cell carcinoma (HNSCC) is the most common malignant tumor in the oral and maxillofacial regions, and long noncoding RNAs (lncRNAs) play crucial roles in the occurrence and progression of HNSCC. The lncRNA lnc-H2AFV-1 was found to be upregulated in HNSCC tissues; however, the function of lnc-H2AFV-1 in regulating HNSCC proliferation and the potential molecular mechanism is unclear. The present study evaluated the expression of lnc-H2AFV-1 in HNSCC tissues using quantitative real-time PCR (qPCR) and associated abundant lnc-H2AFV-1 expression with tumor size. Functionally, lnc-H2AFV-1 significantly promoted the proliferation of HNSCC cells in vitro and in vivo. Quantified N6-methyladenosine (m6A) RNA methylation and dot blot assays revealed that total m6A methylation in HNSCC cells was accompanied by lnc-H2AFV-1 expression. Western blotting showed that the expression of methyltransferase-like (METTL) 3 and METTL14 was consistent with that of lnc-H2AFV-1, whereas the expression of demethylase fat mass and obesity-associated (FTO) was contrary to that of lnc-H2AFV-1. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and MeRIP-qPCR revealed that lnc-H2AFV-1 overexpression led to the elevated expression and maximal m6A methylation of intraflagellar transport (IFT) 80 in HNSCC. In addition, METTL3/14 knockdown decreased IFT80 expression. Thus, our findings suggested that lnc-H2AFV-1 might be a biomarker that alters m6A modification by regulating the m6A methylases METTL3/14 and FTO, and then mediating downstream target IFT80 to promote HNSCC progression.

The Emerging Role of N6-Methyladenosine RNA Methylation as Regulators in Cancer Therapy and Drug Resistance

N6-methyladenosine (m6A) RNA methylation has been considered the most prevalent, abundant, and conserved internal transcriptional modification throughout the eukaryotic mRNAs. Typically, m6A RNA methylation is catalyzed by the RNA methyltransferases (writers), is removed by its demethylases (erasers), and interacts with m6A-binding proteins (readers). Accumulating evidence shows that abnormal changes in the m6A levels of these regulators are increasingly associated with human tumorigenesis and drug resistance. However, the molecular mechanisms underlying m6A RNA methylation in tumor occurrence and development have not been comprehensively clarified. We reviewed the recent findings on biological regulation of m6A RNA methylation and summarized its potential therapeutic strategies in various human cancers.

FTO in cancer: functions, molecular mechanisms, and therapeutic implications

N⁶-methyladenosine (m⁶A) is the most abundant internal modification in mRNA that affects RNA processing, stability, and translation. Discovered as the first RNA m⁶A demethylase, the fat mass and obesity-associated protein (FTO) is frequently dysregulated and plays important roles in various types of cancers. Targeting FTO holds promising therapeutic significance via suppressing tumor growth, potentiating immunotherapy, and attenuating drug resistance. Here, we review recent advances in our understanding of the functions and underlying molecular mechanisms of FTO in tumor development, cancer stem cell (CSC) self-renewal, microenvironment regulation, immunity, and metabolism and discuss the therapeutic potential of targeting FTO for cancer treatment.

N6-Methyladenosine Modification Participates in the Progression of Hepatitis B Virus-Related Liver Fibrosis by Regulating Immune Cell Infiltration

Aim

N6-methyladenosine (m6A) modification has been demonstrated to play an important part in hepatitis B virus (HBV) infection and immune response. This study aims to further investigate whether m6A modification plays an important role in the progression of HBV-related liver fibrosis through the regulation of immune cell infiltration.

Methods

In this study, 124 chronically HBV infected cases were obtained from the Gene Expression Omnibus database. In total, 489 m6A-and-stage related genes were selected to be associated with the m6A modification and the stage of liver fibrosis. Based on these genes, we identified two distinct gene clusters, gene clusterA and gene clusterB. The immune characteristics of the two clusters were comprehensively compared. The m6A-S score was constructed as quantification of individual m6A status. The correlations between m6A regulators and infiltrating immune cells were examined and compared in different pairs of groups with various m6A traits.

Results

Biological functions, immune cell infiltration, and cytokines expression were compared between the two gene clusters proving that the gene clusterB was more immune active and had a more advanced liver fibrosis stage. The m6A-S score was associated with immune infiltration and the progression of liver fibrosis. Five different grouping conditions with different m6A traits were set up. According to the intersection of significant genes and cells, ALKBH5 interacting with macrophage and WTAP interacting with nature killer T cells may be key points in the progress of liver fibrosis.

Conclusions

N6-methyladenosine modification is closely related to the immune cell infiltration and the fibrosis stage of chronic HBV-infected liver tissue. It provides us a better understanding of the progression of liver cirrhosis via evaluating the m6A modification pattern and immune infiltration characteristics.

Identification and validation of the N6-methyladenosine RNA methylation regulator ZC3H13 as a novel prognostic marker and potential target for hepatocellular carcinoma

N6-methyladenosine (m6A) RNA methylation has been implicated in various malignancies. This study aimed to identify prognostic signature based on m6A methylation regulators for hepatocellular carcinoma (HCC) and provide candidate targets for HCC treatment. In this study, the expression levels, prognostic values, correlation with tumor grades and genetic variations of m6A-related genes in HCC were evaluated using bioinformatics analyses. Interestingly, the results show that methyltransferase zinc finger CCCH-type containing 13 (ZC3H13) was expressed at a significantly low level in HCC. Survival outcome analysis suggested that significant correlations existed between ZC3H13 downregulation and poor overall survival (OS) and poor recurrence-free survival (RFS) in HCC patients. Therefore, ZC3H13 was chosen for further experimental validation. The expression of ZC3H13 in HCC cell lines was investigated by western blotting. Knockdown of ZC3H13 significantly enhanced the migration and invasion of HCC cells, as demonstrated by wound healing and transwell assays. Moreover, upregulating ZC3H13 repressed the growth of xenograft tumors in vivo. Functional and pathway enrichment analyses indicated that ZC3H13 might be involved in transcriptional dysregulation or the JAK-STAT signaling pathway in cancer. Additionally, ZC3H13 expression was significantly correlated with lymphocytes and immunomodulators. Therefore, ZC3H13 is a promising candidate as a novel biomarker and therapeutic target for HCC.

MicroRNA miR-124-3p suppresses proliferation and epithelial-mesenchymal transition of hepatocellular carcinoma via ARRDC1 (arrestin domain containing 1)

Hepatocellular carcinoma (HCC) is responsible for high morbidity and mortality worldwide. Increasing evidence suggests that microRNAs intensively participate in HCC development and progression. In the current study, we aimed to explore the impact of miR-124-3p in the proliferation and epithelial-mesenchymal transition (EMT) of HCC. The RT-qPCR assay was employed to determine miR-124-3p expression in human HCC specimens and cell lines. Luciferase assay was used to validate the miR-124-3p target gene. Western Blot and RT-qPCR were performed to study the effects of miR-124-3p modulation on ARRDC1 (Arrestin Domain Containing 1) mRNA and protein expressions. MTT assay, wound healing assay, EdU assay, and Transwell assay were utilized to verify the impact of miR-144-3p modulation on HCC proliferation and EMT via ARRDC1. We found that MiR-124-3p expression downregulates in HCC. Overexpression of miR-124-3p reduced the HCC cell proliferation and EMT. Meanwhile, we determined that the expression of ARRDC1 is increased in HCC, and miR-124-3p directly binds the 3'UTR of ARRDC1 and inhibits its expression at mRNA and protein level, suggesting that miR-124-3p was capable of negatively modulating ARRDC1. Besides, cotransfection of ARRDC1-overexpression plasmid and miR-124-3p mimics increased the cell proliferation and EMT as compared to miR-124-3p mimics. Our study concluded that miR-124-3p directly binds the 3'UTR of ARRDC1 and exerts anti-tumorous effects by inhibiting the HCC proliferation and EMT. Therefore, miR-124-3p/ARRDC1 axis may serve as a novel therapeutic target to inhibit HCC growth and metastasis.

The regulatory role of N6 -methyladenosine modification in the interaction between host and microbes

N⁶ -methyladenosine (m⁶ A) is the most prevalent posttranscriptional modification in eukaryotic mRNAs. Dynamic and reversible m⁶ A modification regulates gene expression to control cellular processes and diverse biological functions. Growing evidence indicated that m⁶ A modification is involved in the homeostasis of host and microbes (mostly viruses and bacteria). Disturbance of m⁶ A modification affects the life cycles of viruses and bacteria, however, these microbes could in turn change host m⁶ A modification leading to human disease including autoimmune diseases and cancer. Thus, we raise the concept that m⁶ A could be a "messenger" molecule to participate in the interactions between host and microbes. In this review, we summarize the regulatory mechanisms of m⁶ A modification on viruses and commensal microbiota, highlight the roles of m⁶ A methylation in the interaction of host and microbes, and finally discuss drugs development targeting m⁶ A modification. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Dysregulated N6-methyladenosine (m6A) processing in hepatocellular carcinoma

N6-methyladenosine (m⁶A) is the most thoroughly studied type of internal RNA modification, as this epigenetic modification is the most abundant in eukaryotic RNAs to date. This modification occurs in various types of RNAs and plays significant roles in dominant RNA-related processes, such as translation, splicing, export and degradation. These processes are catalyzed by three types of prominent enzymes: writers, erasers and readers. Increasing evidence has shown that m⁶A modification is vital for the regulation of gene expression, carcinogenesis, tumor progression and other abnormal changes, and recent studies have shown that m⁶A is important in the development of hepatocellular carcinoma (HCC). Herein, we summarize the nature and regulatory mechanisms of m⁶A modification, including its role in the pathogenesis of HCC and related chronic liver diseases. We also highlight the clinical significance and future strategies involving RNA m⁶A modifications in HCC.

Multi-Omics Investigations Revealed Underlying Molecular Mechanisms Associated With Tumor Stiffness and Identified Sunitinib as a Potential Therapy for Reducing Stiffness in Pituitary Adenomas

Purpose: Pituitary adenomas (PAs) are the second most common intracranial neoplasms. Total surgical resection was extremely important for curing PAs, whereas tumor stiffness has gradually become the most critical factor affecting the resection rate in PAs. We aimed to investigate the molecular mechanisms of tumor stiffening and explore novel medications to reduce stiffness for improving surgical remission rates in PA patients.

Methods: RNA sequencing, whole-genome bisulfite sequencing, and whole exome sequencing were applied to identify transcriptomic, epigenomic, and genomic underpinnings among 11 soft and 11 stiff PA samples surgically resected from patients at Peking Union Medical College Hospital (PUMCH). GH3 cell line and xenograft PA model was used to demonstrate therapeutic effect of sunitinib, and atomic force microscopy (AFM) was used to detect the stiffness of tumors.

Results: Tumor microenvironment analyses and immunofluorescence staining indicated endothelial cells (ECs) and cancer-associated fibroblasts (CAFs) were more abundant in stiff PAs. Weighted gene coexpression network analysis identified the most critical stiffness-related gene (SRG) module, which was highly correlated with stiff phenotype, ECs and CAFs. Functional annotations suggested SRGs might regulate PA stiffness by regulating the development, differentiation, and apoptosis of ECs and CAFs and related molecular pathways. Aberrant DNA methylation and m6A RNA modifications were investigated to play crucial roles in regulating PA stiffness. Somatic mutation analysis revealed increased intratumoral heterogeneity and decreased response to immunotherapy in stiff tumors. Connectivity Map analysis of SRGs and pRRophetic algorithm based on drug sensitivity data of cancer cell lines finally determine sunitinib as a promising agent targeting stiff tumors. Sunitinib inhibited PA growth in vitro and in vivo, and also reduced tumor stiffness in xenograft PA models detected by AFM.

Conclusion: This is the first study investigating the underlying mechanisms contributing to the stiffening of PAs, and providing novel insights into medication therapy for stiff PAs.

SNHG10/miR-141-3p/WTAP axis promotes osteosarcoma proliferation and migration

LncRNAs have been suggested to participate in the growth and metastasis of cancer through a variety of molecular mechanisms. Recently, SNHG10, a newly discovered lncRNA, is reported to play a role of an oncogene in osteosarcoma (OS) genesis. Nonetheless, the mechanism underlying OS remains unclear. The present work found that SNHG10 expression increased within OS cells and tissues, while suppressing its expression decreased OS cell proliferation, migration, invasion, but increased their apoptosis. As for the mechanism, we confirmed that SNHG10 could bind to miR-141-3p, while the latter could bind to WTAP. SNHG10 upregulated WTAP through decreasing miR-141-3p expression. More importantly, SNHG10 deletion remarkably reduced proliferation, migration, and invasion of cells, but accelerated their apoptosis. However, when cells were subjected to miR-141-3p inhibitor cotransfection or overexpressed WTAP, these effects were partially recovered. In summary, this study suggested that the expression of SNHG10 markedly elevated within OS, and the SNHG10/miR-141-3p/WTAP axis facilitated OS progression.

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

N6-methyladenosine (m6A), as the most common RNA modification, plays a vital role in the development of cancers. Circular RNAs (circRNAs) are a class of single-stranded covalently closed RNA molecules. Recently, m6A modification has been identified as performing biological functions for regulating circRNAs. Increasing evidence also shows that circRNAs are involved in cancer progression by targeting m6A regulators. In this review, we describe the functional crosstalk between m6A and circRNAs, and illustrate their roles in cancer development. m6A methylation mediates the biogenesis, stability, and cytoplasmic export of circRNAs in different cancer types. Moreover, circRNAs regulate the expression of m6A regulators, participate in the degradation of m6A regulators, and regulate the m6A modification of target mRNAs. Finally, we discuss the potential applications and future research directions of m6A modification and circRNAs in cancer. Further understanding of the biological roles of m6A and circRNAs will provide new insight into the diagnosis and treatment of cancer patients.

Comprehensive characterization of m6A methylation and its impact on prognosis, genome instability, and tumor microenvironment in hepatocellular carcinoma

Background

N6-methyladenosine (m6A) RNA regulation was recently reported to be important in carcinogenesis and cancer development. However, the characteristics of m6A modification and its correlations with clinical features, genome instability, tumor microenvironments (TMEs), and immunotherapy responses in hepatocellular carcinoma (HCC) have not been fully explored.

Methods

We systematically analyzed the m6A regulator-based expression patterns of 486 patients with HCC from The Cancer Genome Atlas and Gene Expression Omnibus databases, and correlated these patterns with clinical outcomes, somatic mutations, TME cell infiltration, and immunotherapy responses. The m6A score was developed by principal component analysis to evaluate m6A modifications in individual patients.

Results

M6A regulators were dysregulated in HCC samples, among which 18 m6A regulators were identified as risk factors for prognosis. Three m6A regulator-based expression patterns, namely m6A clusters, were determined among HCC patients by m6A regulators with different m6A scores, somatic mutation counts, and specific TME features. Additionally, three distinct m6A regulator-associated gene-based expression patterns were also identified based on prognosis-associated genes that were differentially expressed among the three m6A clusters, showing similar properties as the m6A regulator-based expression patterns. Higher m6A scores were correlated with older age, advanced stages, lower overall survival, higher somatic mutation counts, elevated PD-L1 expression levels, and poorer responses to immune checkpoint inhibitors. The m6A score was validated as an independent and valuable prognostic factor for HCC.

Conclusion

M6A modification is correlated with genome instability and TME in HCC. Evaluating m6A regulator-based expression patterns and the m6A score of individual tumors may help identify candidate biomarkers for prognosis prediction and immunotherapeutic strategy selection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01207-x.

SMC1A regulated by KIAA1429 in m6A-independent manner promotes EMT progress in breast cancer

As a component of N6-methyladenosine (m6A) “writers,” KIAA1429 was reported to promote breast cancer proliferation and growth in m6A-independent manners. However, the related mechanism of KIAA1429 in breast cancer metastasis has not been reported. In the present study, we found KIAA1429 could significantly promote the migration and invasion of breast cancer cells. Then we demonstrated that knockdown of KIAA1429 could impede breast cancer metastasis in nude mice in vivo. The level of SNAIL expression and epithelial-mesenchymal transition (EMT) progress was positively related with KIAA1429. Furthermore, we confirmed that the suppression of cell migration, invasion, and EMT progress by knockdown of KIAA1429 could be reversed by the upregulation of SNAIL. However, structural maintenance of chromosomes 1A (SMC1A), not KIAA1429, bound with the SNAIL promoter region directly and promoted the transcription of SNAIL. Then we confirmed that KIAA1429 could bind to the motif in the 3′ UTR of SMC1A mRNA directly and enhance SMC1A mRNA stability. In conclusion, our study revealed a novel mechanism of the KIAA1429/SMC1A/SNAIL axis in the regulation of metastasis of breast cancer. Moreover, it first provided detailed investigation of how KIAA1429 regulated the targeted gene expression at posttranscriptional levels as an RNA binding protein unrelated to its m6A modification.

ABHD11-AS1: An Emerging Long Non-Coding RNA (lncRNA) with Clinical Significance in Human Malignancies

The aberrant expression of lncRNAs has been linked to the development and progression of different cancers. One such lncRNA is ABHD11 antisense RNA 1 (ABHD11-AS1), which has recently gained attention for its significant role in human malignancies. ABHD11-AS1 is highly expressed in gastric, lung, breast, colorectal, thyroid, pancreas, ovary, endometrium, cervix, and bladder cancers. Several reports highlighted the clinical significance of ABHD11-AS1 in prognosis, diagnosis, prediction of cancer progression stage, and treatment response. Significantly, the levels of ABHD11-AS1 in gastric juice had been exhibited as a clinical biomarker for the assessment of gastric cancer, while its serum levels have prognostic potential in thyroid cancers. The ABHD11-AS1 has been reported to exert oncogenic effects by sponging different microRNAs (miRNAs), altering signaling pathways such as PI3K/Akt, epigenetic mechanisms, and N6-methyladenosine (m⁶A) RNA modification. In contrast, the mouse homolog of AHD11-AS1 (Abhd11os) overexpression had exhibited neuroprotective effects against mutant huntingtin-induced toxicity. Considering the emerging research reports, the authors attempted in this first review on ABHD11-AS1 to summarize and highlight its oncogenic potential and clinical significance in different human cancers. Lastly, we underlined the necessity for future mechanistic studies to unravel the role of ABHD11-AS1 in tumor development, prognosis, progression, and targeted therapeutic approaches.

Diagnostic, Therapeutic, and Prognostic Value of the m6A Writer Complex in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) has poor prognosis and is usually diagnosed only at an advanced stage. Identification of novel biomarkers is critical to early diagnosis and better prognosis for HCC patients. N6-methyladenosine (m⁶A) RNA methylation regulators play important roles in the development of many tumors. However, the m⁶A writer complex, a key executor of m⁶A methylation modification, has not been independently investigated, and its specific bioinformatics analysis has not yet been performed in HCC. In this study, we used multiple public databases to evaluate the diagnostic, therapeutic, and prognostic value of the m⁶A writers in HCC. The results showed that expression levels of METTL3, VIRMA and CBLL1 were significantly increased, while expression levels of METTL14 and ZC3H13 were significantly decreased in HCC, which was closely related to clinicopathological factors, such as tumor stage and prognosis. Bioinformatics further explored the possible underlying mechanisms by which the m⁶A writer complex are involved in activation of tumor-promoting pathways and/or inhibition of tumor-suppressing pathways, including apoptosis, cell cycle, DNA damage response and EMT. Furthermore, we showed that the m⁶A writer complex is correlated with immune cell infiltration and immunoregulator expression in HCC. In conclusion, the m⁶A writer complex may represent a promising biomarker and target that can guide targeted therapy or immunotherapy for HCC patients.

Upregulated WTAP expression in colorectal cancer correlates with tumor site and differentiation

Few reports exist regarding the expression and function of Wilms’ tumor 1-associated protein (WTAP) in colorectal cancer (CRC), and the evidence is controversial. Our analysis explored the expression of WTAP in CRC tissue, and analyzed its clinical and prognostic significance. WTAP expression was significantly higher in CRC tissue than in colorectal adenoma and normal colorectal tissue. WTAP was highest in left colon tumor samples and negatively associated with tumor differentiation, as well as depth of tumor invasion. In multiple logistic regression analysis, independent predictors of WTAP expression in CRC included tumor in the left colon (odds ratio = 2.634; 95% confidence interval: 1.129–6.142; P = 0.025) and poorly differentiated tissue (0.072; 0.014–0.367; P = 0.002). No clear relationship was observed between CRC patient prognosis and WTAP expression. We suggest that WTAP expression is upregulated in CRC, highly expressed in left colon cancer and negatively correlated with tumor differentiation.

N6-Methyladenosine-Related lncRNAs Are Potential Prognostic Biomarkers and Correlated With Tumor Immune Microenvironment in Osteosarcoma

N6-methyladenosine (m6A) and long non-coding RNAs (lncRNAs) play vital roles in the prognostic value and immune microenvironment of malignant tumors. Here, we constructed a m6A-related lncRNA signature in osteosarcoma samples from TCGA dataset and analyzed the association of the signature with tumor immune microenvironment. m6A-related lncRNAs were identified by performing Pearson's correlation analysis and were used to construct a novel m6A-related lncRNA signature in osteosarcoma. Validation in testing and entire cohorts confirmed the satisfactory accuracy of the risk signature. Principal-component analysis verifies the grouping ability of the risk signature. Functional enrichment analyses connected immune with the risk signature based on the six m6A-related lncRNAs. When patients were separated into high- and low-risk group based on their risk scores, we found that patients in the high-risk group had lower stromal scores, immune scores, and ESTIMATE scores, while the tumor purity was higher in the high-risk group than that in the low-risk group. As for immune cell infiltration, the proportion of monocytes was significantly higher in the low-risk group than that in the high-risk group. Of the six lncRNAs, AC004812.2 was a protective factor in osteosarcoma and low expression of AC004812.2 predicted worse overall survival. Overexpression of AC004812.2 inhibited 143B cell proliferation and increased the expression levels of IGF2BP1 and YTHDF1. In all, our m6A-related lncRNA signature was a potential prognostic biomarker and correlated with tumor immune microenvironment and immune cell infiltration, and AC004812.2 might be an important regulator of m6A modification and a promising therapeutic target in osteosarcoma.

Enhancer of zeste homolog 2 promotes hepatocellular cancer progression and chemoresistance by enhancing protein kinase B activation through microRNA-381-mediated SET domain bifurcated 1

Metastasis and chemoresistance are the leading causes of death in patients with hepatocellular carcinoma (HCC). microRNAs (miRNAs or miRs) may be useful as diagnostic, therapeutic and prognostic markers for HCC. In this study, we set out to investigate the possible role of miR-381 in HCC development and chemoresistance along with the related mechanism. Microarray-based gene expression profiling was carried out to analyze the expression of SET domain bifurcated 1 (SETDB1) and histone methyltransferase enhancer of zeste homolog 2 (EZH2) followed by validation in clinical HCC tissues and cells. The potential binding between miR-381 and SETDB1 was found and verified. Then, the role of SETDB1 in HCC in relation to miR-381 and protein kinase B (AKT) pathway was explored through gain- and loss-of-function approaches. After expression determination of EZH2, SETDB1, miR-381, and AKT pathway-related factors, their reactions were analyzed and their functional roles in HCC progression and chemoresistance were investigated in vitro and in vivo. SETDB1 was aberrantly upregulated in clinical HCC tissues and cells. This upregulation activated AKT pathway by promoting its tri-methylation on K64. SETDB1 promoted the proliferation, migration and chemoresistance through the AKT pathway in HCC cells. In a xenograft mouse model, SETDB1 promoted HCC cell tumorigenesis in vivo by activating the AKT pathway. Furthermore, EZH2 suppressed miR-381 by catalyzing the activity of H3K27me3 on its promoter region. In conclusion, EZH2 suppressed miR-381 expression by promoting H3K27me3 activity on its promoter region to facilitate SETDB1 expression, thereby activating the AKT pathway to promote hepatocarcinogenesis and chemoresistance.

m6A modification: recent advances, anticancer targeted drug discovery and beyond

Abnormal N6-methyladenosine (m6A) modification is closely associated with the occurrence, development, progression and prognosis of cancer, and aberrant m6A regulators have been identified as novel anticancer drug targets. Both traditional medicine-related approaches and modern drug discovery platforms have been used in an attempt to develop m6A-targeted drugs. Here, we provide an update of the latest findings on m6A modification and the critical roles of m6A modification in cancer progression, and we summarize rational sources for the discovery of m6A-targeted anticancer agents from traditional medicines and computer-based chemosynthetic compounds. This review highlights the potential agents targeting m6A modification for cancer treatment and proposes the advantage of artificial intelligence (AI) in the discovery of m6A-targeting anticancer drugs. Three stages of m6A-targeting anticancer drug discovery: traditional medicine-based natural products, modern chemical modification or synthesis, and artificial intelligence (AI)-assisted approaches for the future.

Characterization of m6A RNA Methylation Regulators Predicts Survival and Immunotherapy in Lung Adenocarcinoma

N⁶-methyladenosine (m⁶A) RNA modification is a reversible mechanism that regulates eukaryotic gene expression. Growing evidence has demonstrated an association between m⁶A modification and tumorigenesis and response to immunotherapy. However, the overall influence of m⁶A regulators on the tumor microenvironment and their effect on the response to immunotherapy in lung adenocarcinoma remains to be explored. Here, we comprehensively analyzed the m⁶A modification patterns of 936 lung adenocarcinoma samples based on 24 m⁶A regulators. First, we described the features of genetic variation in these m⁶A regulators. Many m⁶A regulators were aberrantly expressed in tumors and negatively correlated with most tumor-infiltrating immune cell types. Furthermore, we identified three m⁶A modification patterns using a consensus clustering method. m⁶A cluster B was preferentially associated with a favorable prognosis and enriched in metabolism-associated pathways. In contrast, m⁶A cluster A was associated with the worst prognosis and was enriched in the process of DNA repair. m⁶A cluster C was characterized by activation of the immune system and a higher stromal cell score. Surprisingly, patients who received radiotherapy had a better prognosis than patients without radiotherapy only in the m⁶A cluster C group. Subsequently, we constructed an m⁶A score model that qualified the m⁶A modification level of individual samples by using principal component analysis algorithms. Patients with high m⁶A score were characterized by enhanced immune cell infiltration and prolonged survival time and were associated with lower tumor mutation burden and PD-1/CTLA4 expression. The combination of the m⁶A score and tumor mutation burden could accurately predict the prognosis of patients with lung adenocarcinoma. Furthermore, patients with high m⁶A score exhibited greater prognostic benefits from radiotherapy and immunotherapy. This study demonstrates that m⁶A modification is significantly associated with tumor microenvironment diversity and prognosis. A comprehensive evaluation of m⁶A modification patterns in single tumors will expand our understanding of the tumor immune landscape. In addition, our m⁶A score model demonstrated that the level of immune cell infiltration plays a significant role in cancer immunotherapy and provides a basis to increase the efficiency of current immune therapies and promote the clinical success of immunotherapy.

Interplay Between m6A RNA Methylation and Regulation of Metabolism in Cancer

Methylation of adenosine in RNA to N6-methyladenosine (m⁶A) is widespread in eukaryotic cells with his integral RNA regulation. This dynamic process is regulated by methylases (editors/writers), demethylases (remover/erasers), and proteins that recognize methylation (effectors/readers). It is now evident that m⁶A is involved in the proliferation and metastasis of cancer cells, for instance, altering cancer cell metabolism. Thus, determining how m⁶A dysregulates metabolic pathways could provide potential targets for cancer therapy or early diagnosis. This review focuses on the link between the m⁶A modification and the reprogramming of metabolism in cancer. We hypothesize that m⁶A modification could dysregulate the expression of glucose, lipid, amino acid metabolism, and other metabolites or building blocks of cells by adaptation to the hypoxic tumor microenvironment, an increase in glycolysis, mitochondrial dysfunction, and abnormal expression of metabolic enzymes, metabolic receptors, transcription factors as well as oncogenic signaling pathways in both hematological malignancies and solid tumors. These metabolism abnormalities caused by m⁶A’s modification may affect the metabolic reprogramming of cancer cells and then increase cell proliferation, tumor initiation, and metastasis. We conclude that focusing on m⁶A could provide new directions in searching for novel therapeutic and diagnostic targets for the early detection and treatment of many cancers.

Functions, mechanisms, and therapeutic implications of METTL14 in human cancer

RNA modification plays a crucial role in many biological functions, and its abnormal regulation is associated with the progression of cancer. Among them, N⁶-methyladenine (m⁶A) is the most abundant RNA modification. Methyltransferase-like 14 (METTL14) is the central component of the m⁶A methylated transferase complex, which is involved in the dynamic reversible process of m⁶A modification. METTL14 acts as both an oncogene and tumor suppressor gene to regulate the occurrence and development of various cancers. The abnormal m⁶A level induced by METTL14 is related to tumorigenesis, proliferation, metastasis, and invasion. To date, the molecular mechanism of METTL14 in various malignant tumors has not been fully studied. In this paper, we systematically summarize the latest research progress on METTL14 as a new biomarker for cancer diagnosis and its biological function in human tumors and discuss its potential clinical application. This study aims to provide new ideas for targeted therapy and improved prognoses in cancer.

Potential applications of N6 -methyladenosine modification in the prognosis and treatment of cancers via modulating apoptosis, autophagy, and ferroptosis

N⁶ -methyladenosine (m⁶ A) is one of the most abundant modifications determining the fate of RNA. Currently, m⁶ A modification is tightly connected with tumorigenesis and presents novel promise in clinical applications. Regulated cell death (RCD) is a programmed mechanism that plays a complicated role in malignant transition. Regarding the main forms of RCD, aberrant levels of m⁶ A modification have been detected during the progression of apoptosis, autophagy, ferroptosis, necroptosis, and pyroptosis in several diseases. However, few reviews have elucidated the correlation between m⁶ A-modified RCD and carcinogenesis. In this review, we summarize the regulators of m⁶ A methylation and their functions in carcinogenesis through an overview of m⁶ A-modified RCD. Additionally, we assume the potential role of m⁶ A modification regulators as novel biomarkers for chemotherapies and precision medicine. Furthermore, we review the controversies and conflicts in m⁶ A explorations and predict future orientations of m⁶ A-modified RCD for clinical applications. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.

METTL14 gene polymorphisms influence hepatoblastoma predisposition in Chinese children: Evidences from a seven-center case-control study

Hepatoblastoma as the most prevalent hepatic malignancy in children, its etiology remains unclear. N⁶-Methyladenosine (m⁶A) modification which can modify various physiological processes, plays a critical role in tumorigenesis. Methyltransferase-like 14 (METTL14), an important component of the m⁶A methyltransferase complex, remains elusive during hepatoblastoma occurrence and development. We explored the relationship between METTL14 gene polymorphisms (rs1064034 T > A, rs298982 G > A, rs62328061 A > G, rs9884978 G > A, and rs4834698 T > C) and hepatoblastoma susceptibility from 313 patients and 1446 controls. The role of METTL14 polymorphisms in hepatoblastoma was evaluated by odds ratios (ORs) and 95% confidence intervals (CIs). Of the included subjects, 308 patients and 1444 controls were successfully genotyped. We did not find any significant correlation between the risk of hepatoblastoma and the five potentially functional METTL14 polymorphisms individually. However, the presence of 4-5 risk genotypes exhibited a significant increased hepatoblastoma risk (adjusted OR = 1.32, 95% CI = 1.03-1.69, P = 0.031) compared to those carriers with 0-3 risk genotypes. Furthermore, the stratified analysis demonstrated that the rs1064034 AA genotype, rs62328061 AG/GG genotypes, rs4834698 TC/CC genotypes, and 4-5 risk genotypes were related to hepatoblastoma susceptibility in certain subgroups. The expression quantitative trait loci (eQTL) analysis revealed that rs1064034 T > A and rs4834698 T > C were correlated with the expression levels of METTL14 and its surrounding genes. Prospectively, these findings suggested that METTL14 polymorphisms may correlation with hepatoblastoma susceptibility and provide a fresh insight into the genetic underpinnings of m⁶A modification in hepatoblastoma.

Current Advances in N6-Methyladenosine Methylation Modification During Bladder Cancer

N6-methyladenosine (m6A) is a dynamic, reversible post-transcriptional modification, and the most common internal modification of eukaryotic messenger RNA (mRNA). Considerable evidence now shows that m6A alters gene expression, thereby regulating cell self-renewal, differentiation, invasion, and apoptotic processes. M6A methylation disorders are directly related to abnormal RNA metabolism, which may lead to tumor formation. M6A methyltransferase is the dominant catalyst during m6A modification; it removes m6A demethylase, promotes recognition by m6A binding proteins, and regulates mRNA metabolic processes. Bladder cancer (BC) is a urinary system malignant tumor, with complex etiology and high incidence rates. A well-differentiated or moderately differentiated pathological type at initial diagnosis accounts for most patients with BC. For differentiated superficial bladder urothelial carcinoma, the prognosis is normally good after surgery. However, due to poor epithelial cell differentiation, BC urothelial cell proliferation and infiltration may lead to invasive or metastatic BC, which lowers the 5-years survival rate and significantly affects clinical treatments in elderly patients. Here, we review the latest progress in m6A RNA methylation research and investigate its regulation on BC occurrence and development.

Roles of m6A modification in neurological diseases

N6-methyladenosine (m6A) methylation modification is one of the most common epigenetic modifications for eukaryotic mRNA. Under the catalytic regulation of relevant enzymes, m6A participates in the body's pathophysiological processes via mediating RNA transcription, splicing, translation, and decay. In the past, we mainly focused on the regulation of m6A in tumors such as hematological tumors, cervical cancer, breast cancer. In recent years, it has been found that m6A is enriched in mRNAs of neurogenesis, cell cycle, and neuron differentiation. Its regulation in the nervous system is gradually being recognized. When the level of m6A modification and the expression levels of relevant enzyme proteins are changed, it will cause neurological dysfunction and participate in the occurrence and conversion of neurological diseases. Recent studies have found that the m6A modification and its associated enzymes were involved in major depressive disorder, Parkinson's disease, Alzheimer's disease, Fragile X syndrome, amyotrophic lateral sclerosis, and traumatic brain injury, and they also play a key role in the development of neurological diseases and many other neurological diseases. This paper mainly reviewed the recent progress of m6A modification-related enzymes, focusing on the impact of m6A modification and related enzyme-mediated regulation of gene expression on the central nervous system diseases, so as to provide potential targets for the prevention of neurological diseases.

Insights into N6-methyladenosine and programmed cell death in cancer

N6-methyladenosine (m6A) methylation, the most common form of internal RNA modification in eukaryotes, has gained increasing attention and become a hot research topic in recent years. M6A plays multifunctional roles in normal and abnormal biological processes, and its role may vary greatly depending on the position of the m6A motif. Programmed cell death (PCD) includes apoptosis, autophagy, pyroptosis, necroptosis and ferroptosis, most of which involve the breakdown of the plasma membrane. Based on the implications of m6A methylation on PCD, the regulators and functional roles of m6A methylation were comprehensively studied and reported. In this review, we focus on the high-complexity links between m6A and different types of PCD pathways, which are then closely associated with the initiation, progression and resistance of cancer. Herein, clarifying the relationship between m6A and PCD is of great significance to provide novel strategies for cancer treatment, and has a great potential prospect of clinical application.

Upregulated WTAP expression appears to both promote breast cancer growth and inhibit lymph node metastasis

It is unclear as to whether Wilms' tumor 1-associated protein (WTAP) promotes or suppresses breast cancer. This immunohistochemistry analysis explored levels of WTAP expression in 347 cases of breast cancer and analyzed the relationship between WTAP expression and the clinicopathological characteristics and prognosis of breast cancer patients. The rate of high WTAP expression was significantly higher in breast cancer tissue than in adjacent normal breast tissue (37.5% vs 0.0%; P < 0.001). WTAP expression was positively associated with tumor size and grade, and negatively associated with axillary lymph node metastasis, estrogen and progesterone receptor status. Rates of high WTAP expression were 66.1% in triple-negative breast cancer (TNBC) tissue and 31.3% in non-TNBC tissue. In multiple logistic regression analysis, independent predictors of WTAP expression in breast cancer included larger tumor size (odds ratio = 1.907; 95% confidence interval: 1.185-3.067; P = 0.008), lymph node metastasis (0.597; 0.373-0.956; P = 0.032) and TNBC status (3.735; 2.056-6.784; P < 0.001). No clear relationship was observed between patient prognosis and WTAP expression. We suggest that WTAP expression is upregulated in breast cancer and appears to both promote tumor growth and inhibit lymph node metastasis.

Novel Insights Into the Multifaceted Functions of RNA n6-Methyladenosine Modification in Degenerative Musculoskeletal Diseases

N⁶-methyladenosine (m⁶A) is an important modification of eukaryotic mRNA. Since the first discovery of the corresponding demethylase and the subsequent identification of m⁶A as a dynamic modification, the function and mechanism of m⁶A in mammalian gene regulation have been extensively investigated. “Writer”, “eraser” and “reader” proteins are key proteins involved in the dynamic regulation of m⁶A modifications, through the anchoring, removal, and interpretation of m⁶A modifications, respectively. Remarkably, such dynamic modifications can regulate the progression of many diseases by affecting RNA splicing, translation, export and degradation. Emerging evidence has identified the relationship between m⁶A modifications and degenerative musculoskeletal diseases, such as osteoarthritis, osteoporosis, sarcopenia and degenerative spinal disorders. Here, we have comprehensively summarized the evidence of the pathogenesis of m⁶A modifications in degenerative musculoskeletal diseases. Moreover, the potential molecular mechanisms, regulatory functions and clinical implications of m⁶A modifications are thoroughly discussed. Our review may provide potential prospects for addressing key issues in further studies.

Advances in the functional roles of N6-methyladenosine modification in cancer progression: mechanisms and clinical implications

N⁶-methyladenosine (m⁶A), the methylation targeting the N⁶ position of adenosine, is the most common internal modification of mRNA in eukaryotes. Considering the roles of m⁶A in regulating gene expression, the investigation of m⁶A roles in the biological processes including cell renewal, differentiation, apoptosis, and invasion of cancer cells has become a hot research topic. There are three kinds of protein involved in m⁶A regulation. The methyltransferases and demethylases cooperatively regulate the m⁶A levels, while the m⁶A reading proteins recognize the m⁶A sites and mediate multiple m⁶A-dependent biological functions including mRNA splicing, transfer, translation, and degradation. At present, a large number of studies have found that the changes of m⁶A levels in tumor cells play a very important role in the occurrence and development of tumors, as well as metastasis and invasion of tumor cells. This review summarizes the different roles of m⁶A modification in the occurrence and development of various cancers, and discusses the possibility of choosing the m⁶A related proteins as potential therapeutic targets.

The role of m6A RNA methylation in cancer metabolism

Metabolic reprogramming is one of the main characteristics of malignant tumors, which is due to the flexible changes of cell metabolism that can meet the needs of cell growth and maintain the homeostasis of tissue environments. Cancer cells can obtain metabolic adaptation through a variety of endogenous and exogenous signaling pathways, which can not only promote the growth of malignant cancer cells, but also start the transformation process of cells to adapt to tumor microenvironment. Studies show that m6A RNA methylation is widely involved in the metabolic recombination of tumor cells. In eukaryotes, m6A methylation is the most abundant modification in mRNA, which is involved in almost all the RNA cycle stages, including regulation the transcription, maturation, translation, degradation and stability of mRNA. M6A RNA methylation can be involved in the regulation of physiological and pathological processes, including cancer. In this review, we discuss the role of m6A RNA methylation modification plays in tumor metabolism-related molecules and pathways, aiming to show the importance of targeting m6A in regulating tumor metabolism.

Non-Coding RNA m6A Modification in Cancer: Mechanisms and Therapeutic Targets

Recently, N6-methyl-adenosine (m6A) ribonucleic acid (RNA) modification, a critical and common internal RNA modification in higher eukaryotes, has generated considerable research interests. Extensive studies have revealed that non-coding RNA m6A modifications (e.g. microRNAs, long non-coding RNAs, and circular RNAs) are associated with tumorigenesis, metastasis, and other tumour characteristics; in addition, they are crucial molecular regulators of cancer progression. In this review, we discuss the relationship between non-coding RNA m6A modification and cancer progression from the perspective of various cancers. In particular, we focus on important mechanisms in tumour progression such as proliferation, apoptosis, invasion and metastasis, tumour angiogenesis. In addition, we introduce clinical applications to illustrate more vividly that non-coding RNA m6A modification has broad research prospects. With this review, we aim to summarize the latest insights and ideas into non-coding RNA m6A modification in cancer progression and targeted therapy, facilitating further research.

m6A Methylation Regulates Osteoblastic Differentiation and Bone Remodeling

Osteoporosis is a prevalent bone disease of the aging population, which is characterized by a decrease in bone mass because of the imbalance of bone metabolism. Although the prevention and treatment of osteoporosis have been explored by different researchers, the mechanisms underlying osteoporosis are not clear exactly. N6 methyladenosine (m6A) is a methylated adenosine nucleotide, which functions through its interaction with the proteins called “writers,” “readers” and “erasers.” The epigenetic regulation of m6A has been demonstrated to affect mRNA processing, nuclear export, translation, and splicing. At the cellular level, m6A modification has been known to affect cell proliferation, differentiation, and apoptosis of bone-related cells, such as bone marrow mesenchymal stem cells (BMSC), osteoblasts, and osteoclasts by regulating the expression of ALP, Runx2, Osterix, VEGF, and other related genes. Furthermore, PTH/Pth1r, PI3K‐Akt, Wnt/β‐Catenin, and other signaling pathways, which play important roles in the regulation of bone homeostasis, are also regulated by m6A. Thus, m6A modification may provide a new approach for osteoporosis treatment. The key roles of m6A modification in the regulation of bone health and osteoporosis are reviewed here in this article.

METTL3-mediated m6A modification of TIMP2 mRNA promotes podocyte injury in diabetic nephropathy

Epigenetic changes are present in many physiological and pathological processes. The N⁶-methyladenosine (m6A) modification is the most common modification in eukaryotic mRNA. However, the role of m6A modification in diabetic nephropathy (DN) remains elusive. Here, we found that m6A modification was significantly upregulated in the kidney of type 1 and type 2 diabetic mice, which was caused by elevated levels of METTL3. Moreover, METTL3 is increased in podocyte of renal biopsy from patients with DN, which is related to renal damage. METTL3 knockout significantly reduced the inflammation and apoptosis in high glucose (HG)-stimulated podocytes, while its overexpression significantly aggravated these responses in vitro. Podocyte-conditional knockout METTL3 significantly alleviated podocyte injury and albuminuria in streptozotocin (STZ)-induced diabetic mice. Therapeutically, silencing METTL3 with adeno-associated virus serotype-9 (AAV9)-shMETTL3 in vivo mitigated albuminuria and histopathological injury in STZ-induced diabetic mice and db/db mice. Mechanistically, METTL3 modulated Notch signaling via the m6A modification of TIMP2 in an insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2)-dependent manner and exerted pro-inflammatory and pro-apoptotic effects. In summary, this study suggested that METTL3-mediated m6A modification is an important mechanism of podocyte injury in DN. Targeting m6A through the writer enzyme METTL3 is a potential approach for the treatment of DN.

KIAA1429 is a potential prognostic marker in colorectal cancer by promoting the proliferation via downregulating WEE1 expression in an m6A-independent manner

N6-methyladenosine (m6A), the most abundant mRNA modification in mammals, is involved in the metabolism of mRNA. KIAA1429 is regarded as the largest m6A methyltransferase and plays an important role in m6A modification. However, the prognostic value and function of KIAA1429 in colorectal cancer (CRC) are unclear. Quantitative real-time PCR and immunohistochemical assays were performed to evaluate the expression of KIAA1429 in CRC tissues. Kaplan-Meier survival curves and log-rank tests were used to assess the association between KIAA1429 expression and the prognosis of patients with CRC. CCK-8 assays, colony formation assays, cell cycle assays, and xenograft experiments were performed to investigate the effect of KIAA1429 on cell proliferation. RNA immunoprecipitation, methylated RNA immunoprecipitation assays, and RNA stability assays were conducted to explore the underlying mechanism. KIAA1429 was significantly upregulated in CRC tissues compared with adjacent normal tissues. Patients with higher expression of KIAA1429 had shorter overall survival than those with lower expression. Functionally, KIAA1429 promoted CRC cell proliferation in vitro and in vivo. Mechanistically, KIAA1429 negatively regulated the expression of WEE1 by decreasing its stability in an m6A-independent manner by binding to the third segment in the 3'-UTR of WEE1 mRNA. Moreover, butyrate decreased the expression of KIAA1429 by downregulating the level of the transcription factor NFκB1. Our findings indicated that KIAA1429 plays an oncogenic role in CRC cells by inhibiting the expression of WEE1 in an m6A-independent manner and is associated with poor survival in CRC patients. These results suggested that KIAA1429 might be a potential prognostic marker for CRC.

METTL3-mediated RNA m6A Hypermethylation Promotes Tumorigenesis and GH Secretion of Pituitary Somatotroph Adenomas

INTRODUCTION

Pituitary growth hormone-secreting (GH) pituitary adenomas (PAs) cause mass effects and dysregulated hypersecretion of GH. However, somatic mutation burden is low in PAs. While progress has been made in identifying the epigenetic changes involved in GH-PA initiation, the precise details of its tumorigenesis in GH-PA patients remains to be elucidated. As N6-methyladenosine (m6A) has been shown to often play a critical role in various tumors, it represents a possible initiation point for the tumorigenesis of pituitary adenomas. However, the role of RNA methylation in GH adenomas remains unclear.

METHODS

Protein expression of m6A regulators was measured by immunohistochemistry. Global levels and distribution of m6A methylation were separately analyzed by m6A enzyme-linked immunosorbent assay and m6A sequencing (m6A-seq). RNA interference and lentivirus knockdown system were used to investigate the role of methyltransferase-like 3 (METTL3) and its m6A- dependent regulatory mechanism in tumor progression and GH secretion.

RESULTS

We show that both METTL3 messenger RNA and protein expression are elevated in GH-PA samples when compared with both normal pituitary tissue specimens and nonsecreting pituitary adenomas. Levels of m6A modification increased in GH-PAs, and hypermethylated RNAs are involved in hormone secretion and cell development. Knockdown of METTL3 in GH3 cell line resulted in decreased cell growth and GH secretion. Importantly, we found that GNAS and GADD45γ act as the downstream targets in this process.

CONCLUSION

Our findings strongly suggest that m6A methyltransferase METTL3 promotes tumor growth and hormone secretion by increasing expression of GNAS and GADD45γ in a m6A-dependent manner. Thus, METTL3 and the methylated RNAs constitute suitable targets for clinical treatment of GH-PAs.

The comprehensive analysis based study of perfluorinated compounds-Environmental explanation of bladder cancer progression

Perfluorinated compounds are emerging organic pollutants widely used in building materials, textiles, and electric equipment. Herein, silico analysis was conducted using bioinformatics approach to assess the potential relationship between bladder cancer and perfluorinated compounds. Transcriptome profiles and data of perfluorinated compounds were obtained from The Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression and Comparative Toxicogenomics databases. Gene Ontology (GO9 and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that interactive genes were mainly enriched in bladder cancer (BC). Transcriptome profiles were used to verify the expression of m6A-related genes at the mRNA and protein levels. Most m6A-related genes predicted BC prognosis. Survival analysis and ROC curves demonstrated that the expression levels of m6A-related genes were associated with BC prognosis. Perfluorooctanoic acid (PFOA) significantly increased the cell proliferation ability and promoted cell invasion capacity. In addition, PFOA significantly increased the cell viability and cell invasion capacity of T24 and BIU-87 cell lines compared with the control group. Taken together, these results show that perfluorinated compounds could promote BC progression. DATA AVAILABILITY: Data and materials are available within the manuscript.

FTO Prevents Thyroid Cancer Progression by SLC7A11 m6A Methylation in a Ferroptosis-Dependent Manner

N6 methyladenosine (m6A) modification serves as a novel epigenetic regulatory mechanism that is heavily implicated in the heredity of tumors. Meanwhile, fat mass and obesity-associated protein (FTO) has the potential to affect the regulation of m6A modification in the mRNA of key oncogenes as well as tumor suppressor genes that facilitate tumor progression. In our study, FTO was downregulated in papillary thyroid carcinoma (PTC) tissues. The role of FTO in PTC was assessed by Cell Counting Kit-8 analysis, cell scratch, migration, invasion experiment, flow cytometry apoptosis analysis, and nude mouse experiment. In addition to RNA-Seq and meRIP-Seq, luciferase reporting and mutation analysis have also identified SLC7A11 as the potential FTO regulatory gene. Moreover, X-ray electron microscopy, glutathione (GSH)/oxidized GSH, GPX, malondialdehyde determination, and western blot helped confirmed that FTO inhibited the development of PTC by downregulating the expression of SLC7A11 through ferroptosis. Finally, a rescue experiment was employed to clarify the relationship between FTO and its specific target gene SLC7A11. FTO is able to inhibit the occurrence of PTC by downregulating SLC7A11 in m6A independently, and it functions as a tumor suppressor gene in PTC. These findings could contribute to our understanding of the tumor malignancy regulated by m6A and might lead to new insights for potential biomarkers and therapeutic targets for the treatment of thyroid papillary carcinoma.

Four m6A RNA Methylation Gene Signatures and Their Prognostic Values in Lung Adenocarcinoma

Introduction: Evidence demonstrates that N6-methyladenosine (m6A) modification plays an increasingly important role in the development of tumors. The aim of this study is to explore the expression of m6A-related regulators in lung adenocarcinoma, identify the effect of altered key factors modified by m6A on the prognosis of patients with lung adenocarcinoma. Methods: A comprehensive analysis of m6A-related gene expressions in patients with lung adenocarcinoma based on The Cancer Genome Atlas database (TCGA) and the CBioPortal database. A prognostic risk score was established based on a linear combination of 4 key gene expression levels using the regression coefficients of the multivariate Cox regression models. Immunohistochemical staining analysis was performed to validate the relationship between the protein expression level of m6A regulators and the prognosis of patients retrospectively. The possible mechanism and prospective therapeutic targets of these key m6A molecules were explored by the M6A2Target database and the CMAP database. Results: Mutation pattern analysis revealed that 32% of 656 patients had genetic alterations. Four genes (writer: methyltransferase like 3 [METTL3] and three readers: insulin like growth factor 2 mRNA binding protein 2 [IGF2BP2], heterogeneous nuclear ribonucleoprotein C [HNRNPC], and heterogeneous nuclear ribonucleoprotein A2/B1 [HNRNPA2B1]) were selected to construct a survival risk prediction model and the results of immunohistochemical staining showed that the expression of these four m6A genes was significantly different between lung adenocarcinoma tissues and normal lung tissues (p < .01). The possible downstream genes and prospective therapeutic targets of these four m6A key molecules were discovered. Conclusion: These four m6A RNA methylation regulators may be effective prognostic and diagnostic factors which can provide auxiliary diagnosis and prognosis of lung adenocarcinoma.