N6-methyladenosine regulates glycolysis of cancer cells through PDK4

Insights into the role of RNA m6A modification in the metabolic process and related diseases

According to the latest consensus, many traditional diseases are considered metabolic diseases, such as cancer, type 2 diabetes, obesity, and cardiovascular disease. Currently, metabolic diseases are increasingly prevalent because of the ever-improving living standards and have become the leading threat to human health. Multiple therapy methods have been applied to treat these diseases, which improves the quality of life of many patients, but the overall effect is still unsatisfactory. Therefore, intensive research on the metabolic process and the pathogenesis of metabolic diseases is imperative. N6-methyladenosine (m6A) is an important modification of eukaryotic RNAs. It is a critical regulator of gene expression that is involved in different cellular functions and physiological processes. Many studies have indicated that m6A modification regulates the development of many metabolic processes and metabolic diseases. In this review, we summarized recent studies on the role of m6A modification in different metabolic processes and metabolic diseases. Additionally, we highlighted the potential m6A-targeted therapy for metabolic diseases, expecting to facilitate m6A-targeted strategies in the treatment of metabolic diseases.

Targeting RNA N6-methyladenosine modification-- a novel therapeutic target for HER2- positive gastric cancer

Gastric cancer is one of the most common cancers and is considered the 5th most frequent occurring cancer worldwide. It has gained great attention from the clinicians and researchers because of high mortality rate. It is generally treated with chemotherapy, radiotherapy, and surgery. Recently, additional treatment options including immunotherapy and targeted therapy and immunotherapy have been developed. However, poor prognosis, limited survival rate of patients, and drug resistance to treatment remain critical problems. To improve treatment options or to overcome the bottleneck of treatment, identification of diagnostic and prognostic markers, determining the most effective therapeutic options, and uncovering the molecular regulations associated with treatment strategies are required. In this regard n6-methyladenosine (m6A) regulation is considered important. This reversible modification plays a crucial role in progression, development and treatment of HER2-positive gastric cancer. Here, we discuss the role of m6A modification in HER2-positive gastric cancer progression through collecting related studies at present. We further discuss the association of m6A modification with therapeutic efficacy in HER2-positive gastric cancer and list some examples. We conclude that modification of m6A can be a new strategy for improving the prognosis and survival rate of HER2-positive gastric cancer patients.

LncRNA taurine upregulated gene 1 in liver disease

Long non-coding RNAs (lncRNAs) are RNA sequences exceeding 200 nucleotides in length that lack protein-coding capacity and participate in diverse biological processes in the human body, particularly exerting a pivotal role in disease surveillance, diagnosis, and progression. Taurine upregulated gene 1 (TUG1) is a versatile lncRNA, and recent studies have revealed that the aberrant expression or function of TUG1 is intricately linked to the pathogenesis of liver diseases. Consequently, we have summarized the current understanding of the mechanism of TUG1 in liver diseases such as liver fibrosis, fatty liver, cirrhosis, liver injury, hepatitis, and liver cancer. Moreover, mounting evidence suggests that interventions targeting TUG1 or its downstream pathways may hold therapeutic promise for liver diseases. This review elucidates the characteristics, mechanisms, and targets of TUG1 in liver diseases, offering a theoretical basis for the prevention, diagnosis, treatment, and prognostic biomarkers of liver diseases.

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

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

SIGNIFICANCE

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

DUSP5 regulated by YTHDF1-mediated m6A modification promotes epithelial-mesenchymal transition and EGFR-TKI resistance via the TGF-β/Smad signaling pathway in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) patients have a dismal survival rate because of cancer metastasis and drug resistance. The study aims to identify the genes that concurrently modulate EMT, metastasis and EGFR-TKI resistance, and to investigate the underlying regulatory mechanisms.

METHODS

Cox regression and Kaplan-Meier analyses were applied to identify prognostic oncogenes in LUAD. Gene set enrichment analysis (GSEA) was used to indicate the biological functions of the gene. Wound-healing and Transwell assays were used to detect migratory and invasive ability. EGFR-TKI sensitivity was evaluated by assessing the proliferation, clonogenic survival and metastatic capability of cancer cells with treatment with gefitinib. Methylated RNA immunoprecipitation (MeRIP) and RNA immunoprecipitation (RIP) analyses established the level of m6A modification present on the target gene and the protein's capability to interact with RNA, respectively. Single-sample gene set enrichment (ssGSEA) algorithm used to investigate levels of immune cell infiltration.

RESULTS

Our study identified dual-specificity phosphatase 5 (DUSP5) as a novel and powerful predictor of adverse outcomes for LUAD by using public datasets. Functional enrichment analysis found that DUSP5 was positively enriched in EMT and transforming growth factor-beta (TGF-β) signaling pathway, a prevailing pathway involved in the induction of EMT. As expected, DUSP5 knockdown suppressed EMT via inhibiting the canonical TGF-β/Smad signaling pathway in in vitro experiments. Consistently, knockdown of DUSP5 was first found to inhibit migratory ability and invasiveness of LUAD cells in in vitro and prevent lung metastasis in in vivo. DUSP5 knockdown re-sensitized gefitinib-resistant LUAD cells to gefitinib, accompanying reversion of EMT progress. In LUAD tissue samples, we found 14 cytosine-phosphate-guanine (CpG) sites of DUSP5 that were negatively associated with DUSP5 gene expression. Importantly, 5'Azacytidine (AZA), an FDA-approved DNA methyltransferase inhibitor, restored DUSP5 expression. Moreover, RIP experiments confirmed that YTH N6-methyladenosine RNA binding protein 1 (YTHDF1), a m6A reader protein, could bind DUSP5 mRNA. YTHDF1 promoted DUSP5 expression and the malignant phenotype of LUAD cells. In addition, the DUSP5-derived genomic model revealed the two clusters with distinguishable immune features and tumor mutational burden (TMB).

CONCLUSIONS

Briefly, our study discovered DUSP5 which was regulated by epigenetic modification, might be a potential therapeutic target, especially in LUAD patients with acquired EGFR-TKI resistance.

Natural products as glycolytic inhibitors for cervical cancer treatment: A comprehensive review

Cervical cancer, a prevalent gynaecological malignancy, presents challenges in late-stage treatment efficacy. Aerobic glycolysis, a prominent metabolic trait in cervical cancer, emerges as a promising target for novel drug discovery. Natural products, originating from traditional medicine, represent a significant therapeutic avenue and primary source for new drug development. This review explores the regulatory mechanisms of glycolysis in cervical cancer and summarises natural compounds that inhibit aerobic glycolysis as a therapeutic strategy. The glycolytic phenotype in cervical cancer is regulated by classical molecules such as HIF-1, HPV virulence factors and specificity protein 1, which facilitate the Warburg effect in cervical cancer. Various natural products, such as artemisinin, shikonin and kaempferol, exert inhibitory effects by downregulating key glycolytic enzymes through signalling pathways such as PI3K/AKT/HIF-1α and JAK2/STAT3. Despite challenges related to drug metabolism and toxicity, these natural compounds provide novel insights and promising avenues for cervical cancer treatment.

Inhibition of METTL3 ameliorates doxorubicin-induced cardiotoxicity through suppression of TFRC-mediated ferroptosis

BACKGROUND

Doxorubicin (DOX) is a chemotherapeutic drug, while its clinical use is greatly limited by the life-threatening cardiotoxicity. N6-methyladenosine (m6A) RNA modification participates in varieties of cellular processes. Nonetheless, it remains elusive whether m6A modification and its methyltransferase METTL3 are involved in the progression of DOX-induced cardiotoxicity (DIC).

METHODS

Mice were administrated with DOX (accumulative dosage of 20 mg/kg) repeatedly to establish a chronic DIC model. Cardiomyocyte-specific conditional METTL3 knockout mice were employed to evaluate the effects of altered m6A RNA modification on DIC. The effects of METTL3 on cardiomyocyte ferroptosis were also examined in response to DOX stimulation.

RESULTS

DOX led to increased levels in m6A modification and METTL3 expression in cardiomyocytes in a c-Jun-dependent manner. METTL3-knockout mice exhibited improved cardiac function, remodeling and injury following DOX insult. Besides, inhibition of METTL3 alleviated DOX-induced iron accumulation and ferroptosis in cardiomyocytes, whereas METTL3 overexpression exerted the opposite effects. Mechanistically, METTL3 promoted m6A modification of TFRC mRNA, a critical gene governing iron uptake, and enhanced its stability through recognition of the m6A reader protein, IGF2BP2. Moreover, pharmacological administration of a highly selective METTL3 inhibitor STM2457 effectively ameliorated DIC in mice.

CONCLUSION

METTL3 plays a cardinal role in the etiology of DIC by regulating cardiac iron metabolism and ferroptosis through TFRC m6A modification. Inhibition of METTL3 might be a potential therapeutic avenue for DIC.

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

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

circRNA6448-14/miR-455-3p/OTUB2 axis stimulates glycolysis and stemness of esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a gastrointestinal malignancy with high incidence. This study aimed to reveal the complete circRNA-miRNA-mRNA regulatory network in ESCC and validate its function mechanism.

METHOD

Expression of OTU Domain-Containing Ubiquitin Aldehyde-Binding Protein 2 (OTUB2) in ESCC was analyzed by bioinformatics to find the binding sites between circRNA6448-14 and miR-455-3p, as well as miR-455-3p and OTUB2. The binding relationships were verified by RNA Immunoprecipitation (RIP) and dual-luciferase assay. The expressions of circRNA6448-14, miR-455-3p, and OTUB2 were detected by quantitative real-time polymerase chain reaction (qRT-PCR). MTT assay measured cell viability, and the spheroid formation assay assessed the ability of stem cell sphere formation. Western blot (WB) determined the expression of marker proteins of stem cell surface and rate-limiting enzyme of glycolysis. The Seahorse XFe96 extracellular flux analyzer measured the rate of extracellular acidification rate and cellular oxygen consumption. Corresponding assay kits assessed cellular glucose consumption, lactate production, and adenosine triphosphate (ATP) generation.

RESULTS

In ESCC, circRNA6448-14 and OTUB2 were highly expressed in contrast to miR-455-3p. Knocking down circRNA6448-14 could prevent the glycolysis and stemness of ESCC cells. Additionally, circRNA6448-14 enhanced the expression of OTUB2 by sponging miR-455-3p. Overexpression of OTUB2 or silencing miR-455-3p reversed the inhibitory effect of knockdown of circRNA6448-14 on ESCC glycolysis and stemness.

CONCLUSION

This research demonstrated that the circRNA6448-14/miR-455-3p/OTUB2 axis induced the glycolysis and stemness of ESCC cells. Our study revealed a novel function of circRNA6448-14, which may serve as a potential therapeutic target for ESCC.

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

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

MRTO4 Enhances Glycolysis to Facilitate HCC Progression by Inhibiting ALDOB

BACKGROUND MRT4 Homolog, Ribosome Maturation Factor (MRTO4) is often upregulated in cancer cells. However, its impact in hepatocellular carcinoma (HCC) is less well understood. Herein, we explored the prognostic and energy metabolism reprogramming role of MRTO4 in HCC. MATERIAL AND METHODS Clinical data were obtained from The Cancer Genome Atlas (TCGA), and the expression of MRTO4 in clinical samples was analyzed. The association between different variables and overall survival (OS) was studied, as well as their potential as independent prognostic factors, using Cox regression analysis. We constructed a nomogram including clinical pathological variables and MRTO4 expression to provide a predictive model for prognosis. Heatmaps, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed the relationship between energy metabolism pathways and MRTO4. We used classic molecular biology research methods, including RT-qPCR, Western blotting, CCK8, TUNEL, Clone formation, Transwell assay, ELISA, and immunohistochemistry, to study the role of MRTO4 in promoting the progression of HCC through glycolysis regulation. RESULTS Our study showed that MRTO4 is an independent prognostic risk factor for HCC and that MRTO4 accelerates glycolysis of HCC cells, promotes proliferation and invasion, and suppresses apoptosis of HCC cells. The underlying mechanism involves MRTO4 promoting glycolysis and accelerating HCC by inhibiting ALDOB. CONCLUSIONS Our study revealed a novel mechanism by which MRTO4 promotes glycolysis and accelerates HCC progression, and suggests that inhibiting MRTO4 could be a potential therapeutic strategy for HCC.

Multi-omics analysis-based macrophage differentiation-associated papillary thyroid cancer patient classifier

BACKGROUND

The reclassification of Papillary Thyroid Carcinoma (PTC) is an area of research that warrants attention. The connection between thyroid cancer, inflammation, and immune responses necessitates considering the mechanisms of differential prognosis of thyroid tumors from an immunological perspective. Given the high adaptability of macrophages to environmental stimuli, focusing on the differentiation characteristics of macrophages might offer a novel approach to address the issues related to PTC subtyping.

METHODS

Single-cell RNA sequencing data of medullary cells infiltrated by papillary thyroid carcinoma obtained from public databases was subjected to dimensionality reduction clustering analysis. The RunUMAP and FindAllMarkers functions were utilized to identify the gene expression matrix of different clusters. Cell differentiation trajectory analysis was conducted using the Monocle R package. A complex regulatory network for the classification of Immune status and Macrophage differentiation-associated Papillary Thyroid Cancer Classification (IMPTCC) was constructed through quantitative multi-omics analysis. Immunohistochemistry (IHC) staining was utilized for pathological histology validation.

RESULTS

Through the integration of single-cell RNA and bulk sequencing data combined with multi-omics analysis, we identified crucial transcription factors, immune cells/immune functions, and signaling pathways. Based on this, regulatory networks for three IMPTCC clusters were established.

CONCLUSION

Based on the co-expression network analysis results, we identified three subtypes of IMPTCC: Immune-Suppressive Macrophage differentiation-associated Papillary Thyroid Carcinoma Classification (ISMPTCC), Immune-Neutral Macrophage differentiation-associated Papillary Thyroid Carcinoma Classification (INMPTCC), and Immune-Activated Macrophage differentiation-associated Papillary Thyroid Carcinoma Classification (IAMPTCC). Each subtype exhibits distinct metabolic, immune, and regulatory characteristics corresponding to different states of macrophage differentiation.

Ginsenoside Rh2 shifts tumor metabolism from aerobic glycolysis to oxidative phosphorylation through regulating the HIF1-α/PDK4 axis in non-small cell lung cancer

BACKGROUND

Ginsenoside Rh2 (G-Rh2), a steroidal compound extracted from roots of ginseng, has been extensively studied in tumor therapy. However, its specific regulatory mechanism in non-small cell lung cancer (NSCLC) is not well understood. Pyruvate dehydrogenase kinase 4 (PDK4), a central regulator of cellular energy metabolism, is highly expressed in various malignant tumors. We investigated the impact of G-Rh2 on the malignant progression of NSCLC and how it regulated PDK4 to influence tumor aerobic glycolysis and mitochondrial function.

METHOD

We examined the inhibitory effect of G-Rh2 on NSCLC through I proliferation assay, migration assay and flow cytometry in vitro. Subsequently, we verified the ability of G-Rh2 to inhibit tumor growth and metastasis by constructing subcutaneous tumor and metastasis models in nude mice. Proteomics analysis was conducted to analyze the action pathways of G-Rh2. Additionally, we assessed glycolysis and mitochondrial function using seahorse, PET-CT, Western blot, and RT-qPCR.

RESULT

Treatment with G-Rh2 significantly inhibited tumor proliferation and migration ability both in vitro and in vivo. Furthermore, G-Rh2 inhibited the tumor's aerobic glycolytic capacity, including glucose uptake and lactate production, through the HIF1-α/PDK4 pathway. Overexpression of PDK4 demonstrated that G-Rh2 targeted the inhibition of PDK4 expression, thereby restoring mitochondrial function, promoting reactive oxygen species (ROS) accumulation, and inducing apoptosis. When combined with sodium dichloroacetate, a PDK inhibitor, it complemented the inhibitory capacity of PDKs, acting synergistically as a detoxifier.

CONCLUSION

G-Rh2 could target and down-regulate the expression of HIF-1α, resulting in decreased expression of glycolytic enzymes and inhibition of aerobic glycolysis in tumors. Additionally, by directly targeting mitochondrial PDK, it elevated mitochondrial oxidative phosphorylation and enhanced ROS accumulation, thereby promoting tumor cells to undergo normal apoptotic processes.

Abnormal changes in metabolites caused by m6A methylation modification: The leading factors that induce the formation of immunosuppressive tumor microenvironment and their promising potential for clinical application

BACKGROUND

N6-methyladenosine (m6A) RNA methylation modifications have been widely implicated in the metabolic reprogramming of various cell types within the tumor microenvironment (TME) and are essential for meeting the demands of cellular growth and maintaining tissue homeostasis, enabling cells to adapt to the specific conditions of the TME. An increasing number of research studies have focused on the role of m6A modifications in glucose, amino acid and lipid metabolism, revealing their capacity to induce aberrant changes in metabolite levels. These changes may in turn trigger oncogenic signaling pathways, leading to substantial alterations within the TME. Notably, certain metabolites, including lactate, succinate, fumarate, 2-hydroxyglutarate (2-HG), glutamate, glutamine, methionine, S-adenosylmethionine, fatty acids and cholesterol, exhibit pronounced deviations from normal levels. These deviations not only foster tumorigenesis, proliferation and angiogenesis but also give rise to an immunosuppressive TME, thereby facilitating immune evasion by the tumor.

AIM OF REVIEW

The primary objective of this review is to comprehensively discuss the regulatory role of m6A modifications in the aforementioned metabolites and their potential impact on the development of an immunosuppressive TME through metabolic alterations.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review aims to elaborate on the intricate networks governed by the m6A-metabolite-TME axis and underscores its pivotal role in tumor progression. Furthermore, we delve into the potential implications of the m6A-metabolite-TME axis for the development of novel and targeted therapeutic strategies in cancer research.

Circ_0053943 complexed with IGF2BP3 drives uveal melanoma progression via regulating N6-methyladenosine modification of Epidermal growth factor receptor

Numerous studies have characterized the critical role of circular RNAs (circRNAs) as regulatory factors in the progression of multiple cancers. However, the biological functions of circRNAs and their underlying molecular mechanisms in the progression of uveal melanoma (UM) remain enigmatic. In this study, we identified a novel circRNA, circ_0053943, through re-analysis of UM microarray data and quantitative RT-PCR. Circ_0053943 was found to be upregulated in UM and to promote the proliferation and metastatic ability of UM cells in both in vitro and in vivo settings. Mechanistically, circ_0053943 was observed to bind to the KH1 and KH2 domains of insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3), thereby enhancing the function of IGF2BP3 by stabilizing its target mRNA. RNA sequencing assays identified epidermal growth factor receptor (EGFR) as a target gene of circ_0053943 and IGF2BP3 at the transcriptional level. Rescue assays demonstrated that circ_0053943 exerts its biological function by stabilizing EGFR mRNA and regulating the downstream mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway. Collectively, circ_0053943 may promote UM progression by stabilizing EGFR mRNA and activating the MAPK/ERK signaling pathway through the formation of a circ_0053943/IGF2BP3/EGFR RNA-protein ternary complex, thus providing a potential biomarker and therapeutic target for UM.

Hepatocyte-specific METTL3 ablation by Alb-iCre mice (GPT), but not by Alb-Cre mice (JAX), resulted in acute liver failure (ALF) and postnatal lethality

AIM

In 2019, to examine the functions of METTL3 in liver and underlying mechanisms, we generated mice with hepatocyte-specific METTL3 homozygous knockout (METTL3Δhep) by simultaneously crossing METTL3fl/fl mice with Alb-iCre mice (GPT) or Alb-Cre mice (JAX), respectively. In this study, we explored the potential reasons why hepatocyte-specific METTL3 homozygous disruption by Alb-iCre mice (GPT), but not by Alb-Cre mice (JAX), resulted in acute liver failure (ALF) and then postnatal lethality.

MAIN METHODS

Mice with hepatocyte-specific METTL3 knockout were generated by simultaneously crossing METTL3fl/fl mice with Alb-iCre mice (GPT; Strain No. T003814) purchased from the GemPharmatech Co., Ltd., (Nanjing, China) or with Alb-Cre mice (JAX; Strain No. 003574) obtained from The Jackson Laboratory, followed by combined-phenotype analysis. The publicly available RNA-sequencing data deposited in the NCBI Gene Expression Omnibus (GEO) database under the accession No.: GSE198512 (postnatal lethality), GSE197800 (postnatal survival) and GSE176113 (postnatal survival) were mined to explore the potential reasons why hepatocyte-specific METTL3 homozygous deletion by Alb-iCre mice (GPT), but not by Alb-Cre mice (JAX), leads to ALF and then postnatal lethality.

KEY FINDINGS

Firstly, we observed that hepatocyte-specific METTL3 homozygous deficiency by Alb-iCre mice (GPT) or by Alb-Cre mice (JAX) caused liver injury, abnormal lipid accumulation and apoptosis. Secondly, we are surprised to find that hepatocyte-specific METTL3 homozygous deletion by Alb-iCre mice (GPT), but not by Alb-Cre mice (JAX), led to ALF and then postnatal lethality. Our findings clearly demonstrated that METTL3Δhep mice (GPT), which are about to die, exhibited the severe destruction of liver histological structure, suggesting that METTL3Δhep mice (GPT) nearly lose normal liver function, which subsequently contributes to ALF, followed by postnatal lethality. Finally, we unexpectedly found that as the compensatory growth responses of hepatocytes to liver injury induced by METTL3Δhep (GPT), the proliferation of METTL3Δhep hepatocytes (GPT), unlike METTL3Δhep hepatocytes (JAX), was not evidenced by the significant increase of Ki67-positive hepatocytes, not accompanied by upregulation of cell-cycle-related genes. Moreover, GO analysis revealed that upregulated genes in METTL3Δhep livers (GPT), unlike METTL3Δhep livers (JAX), are not functionally enriched in terms associated with cell cycle, cell division, mitosis, microtubule cytoskeleton organization, spindle organization, chromatin segregation and organization, and nuclear division, consistent with the loss of compensatory proliferation of METTL3Δhep hepatocytes (GPT) observed in vivo. Thus, obviously, the loss of the compensatory growth capacity of METTL3Δhep hepatocytes (GPT) in response to liver injury might contribute to, at least partially, ALF and subsequently postnatal lethality of METTL3Δhep mice (GPT).

SIGNIFICANCE

These findings from this study and other labs provide strong evidence that these phenotypes (i.e., ALF and postnatal lethality) of METTL3Δhep mice (GPT) might be not the real functions of METTL3, and closely related with Alb-iCre mice (GPT), suggesting that we should remind researchers to use Alb-iCre mice (GPT) with caution to knockout gene in hepatocytes in vivo.

A comprehensive review of m6A research in cervical cancer

Cervical cancer (CC) remains one of the most common malignancies among women worldwide, posing a serious threat to women's health. N6-methyladenosine (m6A) modification, as the most abundant type of RNA methylation modification, and has been found to play a crucial role in various cancers. Current research suggests a close association between RNA m6A modification and the occurrence and progression of CC, encompassing disruptions in m6A levels and its regulatory machinery. This review summarizes the current status of m6A modification research in CC, explores the mechanisms underlying m6A levels and regulators (methyltransferases, demethylases, reader proteins) in CC and examines the application of small-molecule inhibitors of m6A regulators in disease treatment. The findings provide new insights into the future treatment of CC.

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

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

N6-methyladenosine (m6A) modification in hepatocellular carcinoma

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

The RNA m6A reader IGF2BP3 regulates NFAT1/IRF1 axis-mediated anti-tumor activity in gastric cancer

N6-methyladenosine (m6A) and its associated reader protein insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) are involved in tumor initiation and progression via regulating RNA metabolism. This study aims to investigate the biological function and clinical significance of IGF2BP3 in gastric cancer (GC). The clinical significance of IGF2BP3 was evaluated using tumor related databases and clinical tissues. The biological role and molecular mechanism of IGF2BP3 in GC progression were investigated by multi-omics analysis including Ribosome sequence (Ribo-seq), RNA sequence (RNA-seq) and m6A sequence (m6A-seq) combined with gain- and loss- of function experiments. IGF2BP3 expression is significantly elevated in GC tissues and associated with poor prognosis of GC patients. Knockdown of IGF2BP3 significantly weakens the migration and clonogenic ability, promotes the apoptosis, inhibits translation, and suppresses in vitro growth and progression of GC cells. Mechanistically, IGF2BP3 regulates the mRNA stability and translation of the nuclear factor of activated T cells 1(NFAT1) in a m6A dependent manner. Then NFAT1 induced by IGF2BP3 acts as a transcription factor (TF) to negatively regulates the promoter activities of interferon regulatory factor 1 (IRF1) to inhibit its expression. Inhibition of IGF2BP3-induced expression of IRF1 activates interferon (IFN) signaling pathway and then exerts its anti-tumor effect. Elevated IGF2BP3 promotes in vivo and in vitro GC progression via regulation of NFAT1/IRF1 pathways. Targeted inhibition of IGF2BP3 might be a potential therapeutic approach for GC treatment.

IGF2BPs as novel m6A readers: Diverse roles in regulating cancer cell biological functions, hypoxia adaptation, metabolism, and immunosuppressive tumor microenvironment

m6A methylation is the most frequent modification of mRNA in eukaryotes and plays a crucial role in cancer progression by regulating biological functions. Insulin-like growth factor 2 mRNA-binding proteins (IGF2BP) are newly identified m6A 'readers'. They belong to a family of RNA-binding proteins, which bind to the m6A sites on different RNA sequences and stabilize them to promote cancer progression. In this review, we summarize the mechanisms by which different upstream factors regulate IGF2BP in cancer. The current literature analyzed here reveals that the IGF2BP family proteins promote cancer cell proliferation, survival, and chemoresistance, inhibit apoptosis, and are also associated with cancer glycolysis, angiogenesis, and the immune response in the tumor microenvironment. Therefore, with the discovery of their role as 'readers' of m6A and the characteristic re-expression of IGF2BPs in cancers, it is important to elucidate their mechanism of action in the immunosuppressive tumor microenvironment. We also describe in detail the regulatory and interaction network of the IGF2BP family in downstream target RNAs and discuss their potential clinical applications as diagnostic and prognostic markers, as well as recent advances in IGF2BP biology and associated therapeutic value.

METTL3 as a novel diagnosis and treatment biomarker and its association with glycolysis, cuproptosis and ceRNA in oesophageal carcinoma

METTL3 has been shown to be involved in regulating a variety of biological processes. However, the relationship between METTL3 expression and glycolysis, cuproptosis-related genes and the ceRNA network in oesophageal carcinoma (ESCA) remains unclear. ESCA expression profiles from databases were obtained, and target genes were identified using differential analysis and visualization. Immunohistochemistry (IHC) staining assessed METTL3 expression differences. Functional enrichment analysis using GO, KEGG and GSEA was conducted on the co-expression profile of METTL3. Cell experiments were performed to assess the effect of METTL3 interference on tumour cells. Correlation and differential analyses were carried out to assess the relationship between METTL3 with glycolysis and cuproptosis. qRT-PCR was used to validate the effects of METTL3 interference on glycolysis-related genes. Online tools were utilized to screen and construct ceRNA networks based on the ceRNA theory. METTL3 expression was significantly higher in ESCA compared to the controls. The IHC results were consistent with the above results. Enrichment analysis revealed that METTL3 is involved in multiple pathways associated with tumour development. Significant correlations were observed between METTL3 and glycolysis-related genes and cuproptosis-related gene. Experiments confirmed that interfered with METTL3 significantly inhibited glucose uptake and lactate production in tumour cells, and affected the expression of glycolytic-related genes. Finally, two potential ceRNA networks were successfully predicted and constructed. Our study establishes the association between METTL3 overexpression and ESCA progression. Additionally, we propose potential links between METTL3 and glycolysis, cuproptosis and ceRNA, presenting a novel targeted therapy strategy for ESCA.

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

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

Methyltransferase-like 3 modifications of RNAs: Implications for the pathology in the endocrine system

Methyltransferase-like 3 (METTL3) is the most well-known element of N6-methyladenosine modification on RNAs. METTL3 deposits a methyl group onto target RNAs to modify their expression, ultimately regulating various physiological and pathological events. Numerous studies have suggested the significant role of METTL3 in endocrine dysfunction and related disorders. However, reviews that summarize and interpret these studies are lacking. In this review, we systematically analyze such studies, including obesity, type 2 diabetes mellitus (T2DM), T2DM-induced diseases, pancreatic cancer, and thyroid carcinoma. This review indicates that METTL3 contributes remarkably to the endocrine dysfunction and progression of obesity, T2DM, T2DM-induced diseases, pancreatic cancer, and thyroid carcinoma. In conclusion, this review provides a comprehensive interpretation of the mechanism via which METTL3 functions on RNAs and regulates various endocrine dysfunction events and suggest potential associated correlations. Our review, thus, provides a valuable reference for further fundamental studies and clinical applications.

Protein translation: biological processes and therapeutic strategies for human diseases

Protein translation is a tightly regulated cellular process that is essential for gene expression and protein synthesis. The deregulation of this process is increasingly recognized as a critical factor in the pathogenesis of various human diseases. In this review, we discuss how deregulated translation can lead to aberrant protein synthesis, altered cellular functions, and disease progression. We explore the key mechanisms contributing to the deregulation of protein translation, including functional alterations in translation factors, tRNA, mRNA, and ribosome function. Deregulated translation leads to abnormal protein expression, disrupted cellular signaling, and perturbed cellular functions- all of which contribute to disease pathogenesis. The development of ribosome profiling techniques along with mass spectrometry-based proteomics, mRNA sequencing and single-cell approaches have opened new avenues for detecting diseases related to translation errors. Importantly, we highlight recent advances in therapies targeting translation-related disorders and their potential applications in neurodegenerative diseases, cancer, infectious diseases, and cardiovascular diseases. Moreover, the growing interest lies in targeted therapies aimed at restoring precise control over translation in diseased cells is discussed. In conclusion, this comprehensive review underscores the critical role of protein translation in disease and its potential as a therapeutic target. Advancements in understanding the molecular mechanisms of protein translation deregulation, coupled with the development of targeted therapies, offer promising avenues for improving disease outcomes in various human diseases. Additionally, it will unlock doors to the possibility of precision medicine by offering personalized therapies and a deeper understanding of the molecular underpinnings of diseases in the future.

Glycolysis Induced by METTL14 Is Essential for Macrophage Phagocytosis and Phenotype in Cervical Cancer

N 6-methyladenosine (m6A) is the most abundant mRNA modification in mammals and it plays a vital role in various biological processes. However, the roles of m6A on cervical cancer tumorigenesis, especially macrophages infiltrated in the tumor microenvironment of cervical cancer, are still unclear. We analyzed the abnormal m6A methylation in cervical cancer, using CaSki and THP-1 cell lines, that might influence macrophage polarization and/or function in the tumor microenvironment. In addition, C57BL/6J and BALB/c nude mice were used for validation in vivo. In this study, m6A methylated RNA immunoprecipitation sequencing analysis revealed the m6A profiles in cervical cancer. Then, we discovered that the high expression of METTL14 (methyltransferase 14, N6-adenosine-methyltransferase subunit) in cervical cancer tissues can promote the proportion of programmed cell death protein 1 (PD-1)-positive tumor-associated macrophages, which have an obstacle to devour tumor cells. Functionally, changes of METTL14 in cervical cancer inhibit the recognition and phagocytosis of macrophages to tumor cells. Mechanistically, the abnormality of METTL14 could target the glycolysis of tumors in vivo and vitro. Moreover, lactate acid produced by tumor glycolysis has an important role in the PD-1 expression of tumor-associated macrophages as a proinflammatory and immunosuppressive mediator. In this study, we revealed the effect of glycolysis regulated by METTL14 on the expression of PD-1 and phagocytosis of macrophages, which showed that METTL14 was a potential therapeutic target for treating advanced human cancers.

METTL14 drives growth and metastasis of non-small cell lung cancer by regulating pri-miR-93-5p maturation and TXNIP expression

BACKGROUND

Non-small cell lung cancer (NSCLC) is a prevalent and aggressive malignancy responsible for a significant number of cancer-related deaths worldwide. Unraveling the molecular mechanisms governing NSCLC growth and metastasis is crucial for the identification of novel therapeutic targets and the development of effective anti-cancer strategies. One such mechanism of interest is the involvement of METTL14, an RNA methyltransferase implicated in various cellular processes, in NSCLC progression.

OBJECTIVE

The objective of this study was to investigate the role of METTL14 in NSCLC development and metastasis and to elucidate the underlying molecular mechanisms. By understanding the impact of METTL14 on NSCLC pathogenesis, the study aimed to identify potential avenues for targeted therapies in NSCLC treatment.

METHODS

We used bioinformatics and high-throughput transcriptome sequencing analyses to screen regulatory mechanisms affecting NSCLC. The Kaplan-Meier method assessed the correlation between METTL14 expression and the prognosis of NSCLC patients. The effects of manipulated METTL14 on malignant phenotypes of NSCLC cells were examined by colony formation assay, flow cytometry, scratch assay, and Transwell assay. The tumorigenic capacity and metastatic potential of NSCLC cells in vivo were evaluated in nude mice.

RESULTS

METTL14 was overexpressed in NSCLC tissues and cell lines. Its high expression indicated a poor prognosis for NSCLC patients. METTL14 silencing promoted apoptosis and repressed proliferation, migration, and invasion of NSCLC cells. miR-93-5p targeted and inhibited TXNIP. METTL14 increased miR-93-5p expression and matured pri-miR-93-5p through m6A alteration to inhibit TXNIP, thereby inhibiting NSCLC cell apoptosis. By controlling the miR-93-5p/TXNIP axis, METTL14 increased the tumorigenic potential and lung metastasis of NSCLC cells in nude mice.

CONCLUSION

This study revealed a role for METTL14 in the contribution to NSCLC development and metastasis and identified METTL14 as a potential target for NSCLC treatment.

RNA m6A modifications regulate crosstalk between tumor metabolism and immunity

In recent years, m6A modifications in RNA transcripts have arisen as a hot topic in cancer research. Indeed, a number of independent studies have elaborated that the m6A modification impacts the behavior of tumor cells and tumor-infiltrating immune cells, altering tumor cell metabolism along with the differentiation and functional activity of immune cells. This review elaborates on the links between RNA m6A modifications, tumor cell metabolism, and immune cell behavior, discussing this topic from the viewpoint of reciprocal regulation through "RNA m6A-tumor cell metabolism-immune cell behavior" and "RNA m6A-immune cell behavior-tumor cell metabolism" axes. In addition, we discuss the various factors affecting RNA m6A modifications in the tumor microenvironment, particularly the effects of hypoxia associated with cancer cell metabolism along with immune cell-secreted cytokines. Our analysis proposes the conclusion that RNA m6A modifications support widespread interactions between tumor metabolism and tumor immunity. With the current viewpoint that long-term cancer control must tackle cancer cell malignant behavior while strengthening anti-tumor immunity, the recognition of RNA m6A modifications as a key factor provides a new direction for the targeted therapy of tumors. This article is categorized under: RNA Processing > RNA Editing and Modification RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.

YTHDF1 in Tumor Cell Metabolism: An Updated Review

With the advancement of research on m6A-related mechanisms in recent years, the YTHDF protein family within m6A readers has garnered significant attention. Among them, YTHDF1 serves as a pivotal member, playing a crucial role in protein translation, tumor proliferation, metabolic reprogramming of various tumor cells, and immune evasion. In addition, YTHDF1 also exerts regulatory effects on tumors through multiple signaling pathways, and numerous studies have confirmed its ability to assist in the reprogramming of the tumor cell-related metabolic processes. The focus of research on YTHDF1 has shifted in recent years from its m6A-recognition and -modification function to the molecular mechanisms by which it regulates tumor progression, particularly by exploring the regulatory factors that interact with YTHDF1 upstream and downstream. In this review, we elucidate the latest signaling pathway mechanisms of YTHDF1 in various tumor cells, with a special emphasis on its distinctive characteristics in tumor cell metabolic reprogramming. Furthermore, we summarize the latest pathological and physiological processes involving YTHDF1 in tumor cells, and analyze potential therapeutic approaches that utilize YTHDF1. We believe that YTHDF1 represents a highly promising target for future tumor treatments and a novel tumor biomarker.

Upregulation of FAM83F by c-Myc promotes cervical cancer growth and aerobic glycolysis via Wnt/β-catenin signaling activation

Cervical cancer (CC) seriously affects women's health. Therefore, elucidation of the exact mechanisms and identification of novel therapeutic targets are urgently needed. In this study, we identified FAM83F, which was highly expressed in CC cells and tissues, as a potential target. Our clinical data revealed that FAM83F protein expression was markedly elevated in CC tissues and was positively correlated with poor prognosis. Moreover, we observed that FAM83F knockdown significantly inhibited cell proliferation, induced apoptosis, and suppressed glycolysis in CC cells, while its overexpression displayed opposite effects. Mechanistically, FAM83F regulated CC cell growth and glycolysis by the modulation of Wnt/β-catenin pathway. The enhancing effects of FAM83F overexpression on CC cell proliferation and glycolysis could be impaired by the Wnt/β-catenin inhibitor XAV939. Moreover, we found that c-Myc bound to the FAM83F promoter and activated the transcription of FAM83F. Notably, knockdown of FAM83F impaired the enhancement of cell proliferation and glycolysis induced by ectopic c-Myc. Consistent with in vitro findings, results from a xenograft mouse model confirmed the promoting role of FAM83F. In summary, our study demonstrated that FAM83F promoted CC growth and glycolysis through regulating the Wnt/β-catenin pathway, suggesting that FAM83F may be a potential molecular target for CC treatment. Schematic summary of c-Myc-activated FAM83F transcription to promote cervical cancer growth and glycolysis by targeting the Wnt/β-catenin signal pathway.

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.

Targeting histone deacetylase suppresses tumor growth through eliciting METTL14-modified m6 A RNA methylation in ocular melanoma

BACKGROUND

Diversified histone deacetylation inhibitors (HDACis) have demonstrated encouraging outcomes in multiple malignancies. N6-methyladenine (m6 A) is the most prevalent messenger RNA modification that plays an essential role in the regulation of tumorigenesis. Howbeit, an in-depth understanding of the crosstalk between histone acetylation and m6 A RNA modifications remains enigmatic. This study aimed to explore the role of histone acetylation and m6 A modifications in the regulation of tumorigenesis of ocular melanoma.

METHODS

Histone modification inhibitor screening was used to explore the effects of HDACis on ocular melanoma cells. Dot blot assay was used to detect the global m6 A RNA modification level. Multi-omics assays, including RNA-sequencing, cleavage under targets and tagmentation, single-cell sequencing, methylated RNA immunoprecipitation-sequencing (meRIP-seq), and m6 A individual nucleotide resolution cross-linking and immunoprecipitation-sequencing (miCLIP-seq), were performed to reveal the mechanisms of HDACis on methyltransferase-like 14 (METTL14) and FAT tumor suppressor homolog 4 (FAT4) in ocular melanoma. Quantitative real-time polymerase chain reaction (qPCR), western blotting, and immunofluorescent staining were applied to detect the expression of METTL14 and FAT4 in ocular melanoma cells and tissues. Cell models and orthotopic xenograft models were established to determine the roles of METTL14 and FAT4 in the growth of ocular melanoma. RNA-binding protein immunoprecipitation-qPCR, meRIP-seq, miCLIP-seq, and RNA stability assay were adopted to investigate the mechanism by which m6 A levels of FAT4 were affected.

RESULTS

First, we found that ocular melanoma cells presented vulnerability towards HDACis. HDACis triggered the elevation of m6 A RNA modification in ocular melanoma. Further studies revealed that METTL14 served as a downstream candidate for HDACis. METTL14 was silenced by the hypo-histone acetylation status, whereas HDACi restored the normal histone acetylation level of METTL14, thereby inducing its expression. Subsequently, METTL14 served as a tumor suppressor by promoting the expression of FAT4, a tumor suppressor, in a m6 A-YTH N6-methyladenosine RNA-binding protein 1-dependent manner. Taken together, we found that HDACi restored the histone acetylation level of METTL14 and subsequently elicited METTL14-mediated m6 A modification in tumorigenesis.

CONCLUSIONS

These results demonstrate that HDACis exert anti-cancer effects by orchestrating m6 A modification, which unveiling a "histone-RNA crosstalk" of the HDAC/METTL14/FAT4 epigenetic cascade in ocular melanoma.

PDK4-dependent hypercatabolism and lactate production of senescent cells promotes cancer malignancy

Senescent cells remain metabolically active, but their metabolic landscape and resulting implications remain underexplored. Here, we report upregulation of pyruvate dehydrogenase kinase 4 (PDK4) upon senescence, particularly in some stromal cell lines. Senescent cells display a PDK4-dependent increase in aerobic glycolysis and enhanced lactate production but maintain mitochondrial respiration and redox activity, thus adopting a special form of metabolic reprogramming. Medium from PDK4+ stromal cells promotes the malignancy of recipient cancer cells in vitro, whereas inhibition of PDK4 causes tumor regression in vivo. We find that lactate promotes reactive oxygen species production via NOX1 to drive the senescence-associated secretory phenotype, whereas PDK4 suppression reduces DNA damage severity and restrains the senescence-associated secretory phenotype. In preclinical trials, PDK4 inhibition alleviates physical dysfunction and prevents age-associated frailty. Together, our study confirms the hypercatabolic nature of senescent cells and reveals a metabolic link between cellular senescence, lactate production, and possibly, age-related pathologies, including but not limited to cancer.

N6-methyladenosine (m6A) Modification in Preeclampsia

Recently, epitranscriptional modification of N6-methyladenosine (m6A) has received growing attention in the research on the pathogenesis of preeclampsia. Advances in m6A sequencing have revealed the molecular mechanism and importance of m6A modification. In addition, epitranscriptional modification of m6A is closely related to the metabolic processes of placental tissues and cells in preeclampsia. This article reviews the composition, mode of action, and bioinformatics analysis of m6A modification-related proteins, and their biological function in the progression of preeclampsia. The relationship between m6A modification and preeclampsia risk factors, such as diabetes, cardiovascular disease, obesity, and psychological stress, is summarized to provide new ideas for studying PE-targeting molecules.

Circular RNA cFAM210A, degradable by HBx, inhibits HCC tumorigenesis by suppressing YBX1 transactivation

Hepatitis B protein x (HBx) has been reported to promote tumorigenesis in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), but the mechanism awaits further investigation. In this study, we found that cFAM210A (a circular RNA derived from the third exon of transcript NM_001098801 of the FAM210A gene; CircBase ID: hsa_circ_0003979) can be silenced by HBx. cFAM210A expression was downregulated and negatively correlated with tumorigenesis in patients with HBV-related HCC. Furthermore, cFAM210A reduced the proliferation, stemness, and tumorigenicity of HCC cells. Mechanistically, HBx increased the N6-methyladenosine (m6A) level of cFAM210A by promoting the expression of RBM15 (an m6A methyltransferase), thus inducing the degradation of cFAM210A via the YTHDF2-HRSP12-RNase P/MRP pathway. cFAM210A bound to YBX1 and inhibited its phosphorylation, suppressing its transactivation function toward MET. These findings suggest the important role of circular RNAs in HBx-induced hepatocarcinogenesis and identify cFAM210A a potential target in the prevention and treatment of HBV-related HCC.

LncRNA BCAN-AS1 stabilizes c-Myc via N6-methyladenosine-mediated binding with SNIP1 to promote pancreatic cancer

C-Myc overexpression contributes to multiple hallmarks of human cancer but directly targeting c-Myc is challenging. Identification of key factors involved in c-Myc dysregulation is of great significance to develop potential indirect targets for c-Myc. Herein, a collection of long non-coding RNAs (lncRNAs) interacted with c-Myc is detected in pancreatic ductal adenocarcinoma (PDAC) cells. Among them, lncRNA BCAN-AS1 is identified as the one with highest c-Myc binding enrichment. BCAN-AS1 was abnormally elevated in PDAC tumors and high BCAN-AS1 level was significantly associated with poor prognosis. Mechanistically, Smad nuclear-interacting protein 1 (SNIP1) was characterized as a new N6-methyladenosine (m6A) mediator binding to BCAN-AS1 via recognizing its m6A modification. m6A-modified BCAN-AS1 acts as a scaffold to facilitate the formation of a ternary complex together with c-Myc and SNIP1, thereby blocking S phase kinase-associated protein 2 (SKP2)-mediated c-Myc ubiquitination and degradation. Biologically, BCAN-AS1 promotes malignant phenotypes of PDAC in vitro and in vivo. Treatment of metastasis xenograft and patient-derived xenograft mouse models with in vivo-optimized antisense oligonucleotide of BCAN-AS1 effectively represses tumor growth and metastasis. These findings shed light on the pro-tumorigenic role of BCAN-AS1 and provide an innovant insight into c-Myc-interacted lncRNA in PDAC.

TNFα increases the degradation of pyruvate dehydrogenase kinase 4 by the Lon protease to support proinflammatory genes

The endothelium is a major target of the proinflammatory cytokine, tumor necrosis factor alpha (TNFα). Exposure of endothelial cells (EC) to proinflammatory stimuli leads to an increase in mitochondrial metabolism; however, the function and regulation of elevated mitochondrial metabolism in EC in response to proinflammatory cytokines remain unclear. Studies using high-resolution metabolomics and 13C-glucose and 13C-glutamine labeling flux techniques showed that pyruvate dehydrogenase activity (PDH) and oxidative tricarboxylic acid cycle (TCA) flux are elevated in human umbilical vein ECs in response to overnight (16 h) treatment with TNFα (10 ng/mL). Mechanistic studies indicated that TNFα mediated these metabolic changes via mitochondrial-specific protein degradation of pyruvate dehydrogenase kinase 4 (PDK4, inhibitor of PDH) by the Lon protease via an NF-κB-dependent mechanism. Using RNA sequencing following siRNA-mediated knockdown of the catalytically active subunit of PDH, PDHE1α (PDHA1 gene), we show that PDH flux controls the transcription of approximately one-third of the genes that are up-regulated by TNFα stimulation. Notably, TNFα-induced PDH flux regulates a unique signature of proinflammatory mediators (cytokines and chemokines) but not inducible adhesion molecules. Metabolomics and ChIP sequencing for acetylated modification on lysine 27 of histone 3 (H3K27ac) showed that TNFα-induced PDH flux promotes histone acetylation of specific gene loci via citrate accumulation and ATP-citrate lyase-mediated generation of acetyl CoA. Together, these results uncover a mechanism by which TNFα signaling increases oxidative TCA flux of glucose to support TNFα-induced gene transcription through extramitochondrial acetyl CoA generation and histone acetylation.

N 6-methyladenosine Modification of FZR1 mRNA Promotes Gemcitabine Resistance in Pancreatic Cancer

The therapeutic options for treating pancreatic ductal adenocarcinoma (PDAC) are limited, and resistance to gemcitabine, a cornerstone of PDAC chemotherapy regimens, remains a major challenge. N6-methyladenosine (m6A) is a prevalent modification in mRNA that has been linked to diverse biological processes in human diseases. Herein, by characterizing the global m6A profile in a panel of gemcitabine-sensitive and gemcitabine-insensitive PDAC cells, we identified a key role for elevated m6A modification of the master G0-G1 regulator FZR1 in regulating gemcitabine sensitivity. Targeting FZR1 m6A modification augmented the response to gemcitabine treatment in gemcitabine-resistant PDAC cells both in vitro and in vivo. Mechanistically, GEMIN5 was identified as a novel m6A mediator that specifically bound to m6A-modified FZR1 and recruited the eIF3 translation initiation complex to accelerate FZR1 translation. FZR1 upregulation maintained the G0-G1 quiescent state and suppressed gemcitabine sensitivity in PDAC cells. Clinical analysis further demonstrated that both high levels of FZR1 m6A modification and FZR1 protein corresponded to poor response to gemcitabine. These findings reveal the critical function of m6A modification in regulating gemcitabine sensitivity in PDAC and identify the FZR1-GEMIN5 axis as a potential target to enhance gemcitabine response.

SIGNIFICANCE

Increased FZR1 translation induced by m6A modification engenders a gemcitabine-resistant phenotype by inducing a quiescent state and confers a targetable vulnerability to improve treatment response in PDAC.

Construction of the metabolic reprogramming-associated gene signature for clear cell renal cell carcinoma prognosis prediction

BACKGROUND

Metabolism reprogramming is a hallmark that associates tumor growth, metastasis, progressive, and poor prognosis. However, the metabolism-related molecular patterns and mechanism in clear cell renal cell carcinoma (ccRCC) remain unclear. Herein, the purpose of this study was to identify metabolism-related molecular pattern and to investigate the characteristics and prognostic values of the metabolism-related clustering.

METHODS

We comprehensively analyzed the differentially expressed genes (DEGs), and metabolism-related genes (MAGs) in ccRCC based on the TCGA database. Consensus clustering was used to construct a metabolism-related molecular pattern. Then, the biological function, molecular characteristics, Estimate/immune/stomal scores, immune cell infiltration, response to immunotherapy, and chemotherapy were analyzed. We also identified the DEGs between subclusters and constructed a poor signature and risk model based on LASSO regression cox analysis and univariable and multivariable cox regression analyses. Then, a predictive nomogram was constructed and validated by calibration curves.

RESULTS

A total of 1942 DEGs (1004 upregulated and 838 downregulated) between ccRCC tumor and normal samples were identified, and 254 MRGs were screened out from those DEGs. Then, 526 ccRCC patients were divided into two subclusters. The 7 metabolism-related pathways enriched in cluster 2. And cluster 2 with high Estimate/immune/stomal scores and poor survival. While, cluster 1 with higher immune cell infiltrating, expression of the immune checkpoint, IFN, HLA, immune activation-related genes, response to anti-CTLA4 treatment, and chemotherapy. Moreover, we identified 295 DEGs between two metabolism-related subclusters and constructed a 15-gene signature and 9 risk factors. Then, a risk score was calculated and the patients into high- and low-risk groups in TCGA-KIRC and E-MTAB-1980 datasets. And the prediction viability of the risk score was validated by ROC curves. Finally, the clinicopathological characteristics (age and stage), risk score, and molecular clustering, were identified as independent prognostic variables, and were used to construct a nomogram for 1-, 3-, 5-year overall survival predicting. The calibration curves were used to verify the performance of the predicted ability of the nomogram.

CONCLUSION

Our finding identified two metabolism-related molecular subclusters for ccRCC, which facilitates the estimation of response to immunotherapy and chemotherapy, and prognosis after treatment.

PARP1 modulates METTL3 promoter chromatin accessibility and associated LPAR5 RNA m6A methylation to control cancer cell radiosensitivity

Chromatin remodeling and N6-methyladenosine (m6A) modification are two critical layers in controlling gene expression and DNA damage signaling in most eukaryotic bioprocesses. Here, we report that poly(ADP-ribose) polymerase 1 (PARP1) controls the chromatin accessibility of METTL3 to regulate its transcription and subsequent m6A methylation of poly(A)+ RNA in response to DNA damage induced by radiation. The transcription factors nuclear factor I-C (NFIC) and TATA binding protein (TBP) are dependent on PARP1 to access the METTL3 promoter to activate METTL3 transcription. Upon irradiation or PARP1 inhibitor treatment, PARP1 disassociated from METTL3 promoter chromatin, which resulted in attenuated accessibility of NFIC and TBP and, consequently, suppressed METTL3 expression and RNA m6A methylation. Lysophosphatidic Acid Receptor 5 (LPAR5) mRNA was identified as a target of METTL3, and m6A methylation was located at A1881. The level of m6A methylation of LPAR5 significantly decreased, along with METTL3 depression, in cells after irradiation or PARP1 inhibition. Mutation of the LPAR5 A1881 locus in its 3' UTR results in loss of m6A methylation and, consequently, decreased stability of LPAR5 mRNA. METTL3-targeted small-molecule inhibitors depress murine xenograft tumor growth and exhibit a synergistic effect with radiotherapy in vivo. These findings advance our comprehensive understanding of PARP-related biological roles, which may have implications for developing valuable therapeutic strategies for PARP1 inhibitors in oncology.

Rna M6 a Methylation Regulates Glycolysis of Beige Fat and Contributes to Systemic Metabolic Homeostasis

N6-methyladenosine (m6 A) modification has been implicated in the progression of obesity and metabolic diseases. However, its impact on beige fat biology is not well understood. Here, via m6 A-sequencing and RNA-sequencing, this work reports that upon beige adipocytes activation, glycolytic genes undergo major events of m6 A modification and transcriptional activation. Genetic ablation of m6 A writer Mettl3 in fat tissues reveals that Mettl3 deficiency in mature beige adipocytes leads to suppressed glycolytic capability and thermogenesis, as well as reduced preadipocytes proliferation via glycolytic product lactate. In addition, specific modulation of Mettl3 in beige fat via AAV delivery demonstrates consistently Mettl3's role in glucose metabolism, thermogenesis, and beige fat hyperplasia. Mechanistically, Mettl3 and m6 A reader Igf2bp2 control mRNA stability of key glycolytic genes in beige adipocytes. Overall, these findings highlight the significance of m6 A on fat biology and systemic energy homeostasis.

Arginine methylation of PPP1CA by CARM1 regulates glucose metabolism and affects osteogenic differentiation and osteoclastic differentiation

BACKGROUND

The imbalance between osteoblasts and osteoclasts may lead to osteoporosis. Osteoblasts and osteoclasts have different energy requirements, with aerobic glycolysis being the prominent metabolic feature of osteoblasts, while osteoclast differentiation and fusion are driven by oxidative phosphorylation.

METHODS

By polymerase chain reaction as well as Western blotting, we assayed coactivator-associated arginine methyltransferase 1 (CARM1) expression in bone tissue, the mouse precranial osteoblast cell line MC3T3-E1 and the mouse monocyte macrophage leukaemia cell line RAW264.7, and expression of related genes during osteogenic differentiation and osteoclast differentiation. Using gene overexpression (lentivirus) and loss-of-function approach (CRISPR/Cas9-mediated knockout) in vitro, we examined whether CARM1 regulates osteogenic differentiation and osteoblast differentiation by metabolic regulation. Transcriptomic assays and metabolomic assays were used to find the mechanism of action of CARM1. Furthermore, in vitro methylation assays were applied to clarify the arginine methylation site of PPP1CA by CARM1.

RESULTS

We discovered that CARM1 reprogrammed glucose metabolism in osteoblasts and osteoclasts from oxidative phosphorylation to aerobic glycolysis, thereby promoting osteogenic differentiation and inhibiting osteoclastic differentiation. In vivo experiments revealed that CARM1 significantly decreased bone loss in osteoporosis model mice. Mechanistically, CARM1 methylated R23 of PPP1CA, affected the dephosphorylation of AKT-T450 and AMPK-T172, and increased the activities of phosphofructokinase-1 and pructose-2,6-biphosphatase3, causing an up-regulation of glycolytic flux. At the same time, as a transcriptional coactivator, CARM1 regulated the expression of pyruvate dehydrogenase kinase 3, which resulted in the inhibition of pyruvate dehydrogenase activity and inhibition of the tricarboxylic acid cycle, leading to a subsequent decrease in the flux of oxidative phosphorylation.

CONCLUSIONS

These findings reveal for the first time the mechanism by which CARM1 affects both osteogenesis and osteoclast differentiation through metabolic regulation, which may represent a new feasible treatment strategy for osteoporosis.

m6A-regulated tumor glycolysis: new advances in epigenetics and metabolism

Glycolytic reprogramming is one of the most important features of cancer and plays an integral role in the progression of cancer. In cancer cells, changes in glucose metabolism meet the needs of self-proliferation, angiogenesis and lymphangiogenesis, metastasis, and also affect the immune escape, prognosis evaluation and therapeutic effect of cancer. The n6-methyladenosine (m6A) modification of RNA is widespread in eukaryotic cells. Dynamic and reversible m6A modifications are widely involved in the regulation of cancer stem cell renewal and differentiation, tumor therapy resistance, tumor microenvironment, tumor immune escape, and tumor metabolism. Lately, more and more evidences show that m6A modification can affect the glycolysis process of tumors in a variety of ways to regulate the biological behavior of tumors. In this review, we discussed the role of glycolysis in tumor genesis and development, and elaborated in detail the profound impact of m6A modification on different tumor by regulating glycolysis. We believe that m6A modified glycolysis has great significance and potential for tumor treatment.

Methyltransferase like 3 inhibition limits intrahepatic cholangiocarcinoma metabolic reprogramming and potentiates the efficacy of chemotherapy

N6-methyladenosine (m6A) RNA methylation and its associated methyltransferase like 3 (METTL3) are involved in the development and maintenance of various tumors. The present study aimed to evaluate the cross-talk of METTL3 with glucose metabolism and reveal a novel mechanism for intrahepatic cholangiocarcinoma (ICC) progression. Real-time quantitative PCR, western blotting, and immunohistochemistry analyses suggested that METTL3 was highly expressed in ICC, which was correlated with poor patient prognosis. Immunoprecipitation sequencing of m6A-RNA showed that METTL3 upregulated m6A modification of NFAT5, which recruited IGF2BP1 for NFAT5 mRNA stabilization. Elevated expression of NFAT5 increased the expression of the gluconeogenesis-related genes GLUT1 and PGK1, resulting in enhanced aerobic glycolysis, proliferation, and tumor metastasis of ICC. Moreover, higher METTL3 expression was observed in tumor tissues of ICC patients with activated ICC glucose metabolism. Importantly, STM2457, a highly potent METTL3 inhibitor, which inhibited METTL3 activity and acted synergistically with gemcitabine, suggests that reprogramming RNA epigenetic modifications may serve as a potential therapeutic strategy. Overall, our findings highlighted the role of METTL3-mediated m6A modification of NFAT5 in activating glycolytic reprogramming in ICC and proposed that the METTL3/NFAT5 axis was a clinical target for the management of ICC chemoresistance by targeting cancer glycolysis.

circRPS19 affects HK2‑mediated aerobic glycolysis and cell viability via the miR‑125a‑5p/USP7 pathway in gastric cancer

Despite advances in diagnosis and treatment, gastric cancer (GC) remains a refractory disease, which limits overall survival. Therefore, it is key to identify novel targets to develop more effective and precise treatment. Circular RNAs (circRNAs) serve essential roles in the process of various human cancers. Through analyzing GSE83521 dataset, the present study identified a novel circRNA derived from ribosomal protein S19 (circRPS19), which was considered a potential treatment target for GC. Results of RT‑qPCR indicated that circRPS19 was upregulated in GC compared with normal gastric epithelial cells. Loss‑of function assays revealed that silencing of circRPS19 suppressed proliferation and aerobic glycolysis but increased apoptosis of GC cells. circRPS19 upregulated ubiquitin‑specific processing protease 7 (USP7) expression by sponging microRNA (miR)‑125a‑5p. circRPS19 stabilized hexokinase 2 (HK2) protein by USP7‑mediated deubiquitination of HK2. In vivo experiments confirmed that circRPS19 promoted GC progression and aerobic glycolysis. Taken together, circRPS19 induced aerobic glycolysis of GC cells by stabilizing HK2 protein via the miR‑125a‑5p/USP7 axis and thus promoting the progression of GC. These findings suggested that circRPS19 served a critical role in the progression of GC and may be a novel therapeutic target for GC.

N4-Acetylcytidine Drives Glycolysis Addiction in Gastric Cancer via NAT10/SEPT9/HIF-1α Positive Feedback Loop

Anti-angiogenic therapy has long been considered a promising strategy for solid cancers. Intrinsic resistance to hypoxia is a major cause for the failure of anti-angiogenic therapy, but the underlying mechanism remains unclear. Here, it is revealed that N4-acetylcytidine (ac4C), a newly identified mRNA modification, enhances hypoxia tolerance in gastric cancer (GC) cells by promoting glycolysis addiction. Specifically, acetyltransferase NAT10 transcription is regulated by HIF-1α, a key transcription factor of the cellular response to hypoxia. Further, acRIP-sequencing, Ribosome profiling sequencing, RNA-sequencing, and functional studies confirm that NAT10 in turn activates the HIF-1 pathway and subsequent glucose metabolism reprogramming by mediating SEPT9 mRNA ac4C modification. The formation of the NAT10/SEPT9/HIF-1α positive feedback loop leads to excessive activation of the HIF-1 pathway and induces glycolysis addiction. Combined anti-angiogenesis and ac4C inhibition attenuate hypoxia tolerance and inhibit tumor progression in vivo. This study highlights the critical roles of ac4C in the regulation of glycolysis addiction and proposes a promising strategy to overcome resistance to anti-angiogenic therapy by combining apatinib with ac4C inhibition.

The roles and implications of RNA m6A modification in cancer

N6-Methyladenosine (m6A), the most prevalent internal modification in eukaryotic mRNA, has been extensively and increasingly studied over the past decade. Dysregulation of RNA m6A modification and its associated machinery, including writers, erasers and readers, is frequently observed in various cancer types, and the dysregulation profiles might serve as diagnostic, prognostic and/or predictive biomarkers. Dysregulated m6A modifiers have been shown to function as oncoproteins or tumour suppressors with essential roles in cancer initiation, progression, metastasis, metabolism, therapy resistance and immune evasion as well as in cancer stem cell self-renewal and the tumour microenvironment, highlighting the therapeutic potential of targeting the dysregulated m6A machinery for cancer treatment. In this Review, we discuss the mechanisms by which m6A modifiers determine the fate of target RNAs and thereby influence protein expression, molecular pathways and cell phenotypes. We also describe the state-of-the-art methodologies for mapping global m6A epitranscriptomes in cancer. We further summarize discoveries regarding the dysregulation of m6A modifiers and modifications in cancer, their pathological roles, and the underlying molecular mechanisms. Finally, we discuss m6A-related prognostic and predictive molecular biomarkers in cancer as well as the development of small-molecule inhibitors targeting oncogenic m6A modifiers and their activity in preclinical models.

Long noncoding RNA AI662270 promotes kidney fibrosis through enhancing METTL3-mediated m6 A modification of CTGF mRNA

The sustained release of profibrotic cytokines, mainly transforming growth factor-β (TGF-β), leads to the occurrence of kidney fibrosis and chronic kidney disease (CKD). Connective tissue growth factor (CTGF) appears to be an alternative target to TGF-β for antifibrotic therapy in CKD. In this study, we found that long noncoding RNA AI662270 was significantly increased in various renal fibrosis models. In vivo, ectopic expression of AI662270 alone was sufficient to activate interstitial fibroblasts and drive kidney fibrosis, whereas inhibition of AI662270 blocked the activation of interstitial fibroblasts and ameliorated kidney fibrosis in various murine models. Mechanistic studies revealed that overexpression of AI662270 significantly increased CTGF product, which was required for the role of AI662270 in driving kidney fibrosis. Furthermore, AI662270 binds to the CTGF promoter and directly interacts with METTL3, the methyltransferase of RNA N6 -methyladenosine (m6 A) modification. Functionally, AI662270-mediated recruitment of METTL3 increased the m6 A methylation of CTGF mRNA and consequently enhanced CTGF mRNA stability. In conclusion, our results support that AI662270 promotes CTGF expression at the posttranscriptional stage by recruiting METTL3 to the CTGF promoter and depositing m6 A modifications on the nascent mRNA, thereby, uncovering a novel regulatory mechanism of CTGF in the pathogenesis of kidney fibrosis.

Regulatory mechanisms and therapeutic implications of insulin-like growth factor 2 mRNA-binding proteins, the emerging crucial m6A regulators of tumors

Insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs) serve essential biological functions as post-transcriptional performers, participating in the acquisition or maintenance of tumor hallmarks due to their distinct protein structures. Emerging evidence indicates that IGF2BPs belong to the class III type of RNA N6-methyladenosine (m6A) modification readers, controlling RNA stability, storage, localization, metabolism, and translation in multiple vital bioprocesses, particularly tumorigenesis and tumor progression. Here, we discuss the underlying regulatory mechanisms and pathological functions of IGF2BPs which act as m6A readers in the context of tumor pathogenesis and multidrug resistance. Furthermore, we highlight the potential of IGF2BPs as drug targets in clinical tumor treatment. Hence, precise and novel tumor therapeutic approaches could be uncovered by targeting epigenetic heterogeneity.