m6A RNA methylation and beyond - The epigenetic machinery and potential treatment options

METTL3 enhances esophageal squamous cell carcinoma progression by suppressing ferroptosis through the PBX3/CA9 cascade

BACKGROUND

N6-methyladenosine (m6A) modification controls various processes during tumorigenesis. Although METTL3 functions as a pro-tumorigenic driver in esophageal squamous cell carcinoma (ESCC), its mechanisms are largely unknown.

METHODS

mRNA expression was detected by quantitative PCR, and protein expression was assessed by immunoblotting. Cell motility, invasiveness, and apoptosis were analyzed by wound-healing assay, transwell assay and flow cytometry, respectively. Cell ferroptosis was assessed by detecting the contents of ROS, MDA and Fe2+. The METTL3/PBX3 and PBX3/CA9 relationships were validated by luciferase, MeRIP or ChIP assay. The effect of METTL3 on tumor growth was tested by xenograft studies.

RESULTS

METTL3 was enhanced in ESCC tumors and cells, and its deficiency suppressed ESCC cell migration and invasion and promoted cell apoptosis and ferroptosis. Additionally, METTL3 deficiency caused growth inhibition of ESCC xenografts in vivo. METTL3 enhanced m6A modification of PBX3 mRNA. PBX3 was identified as a mediator of METTL3 function in modulating ESCC cell phenotypes. PBX3 promoted CA9 transcription, and METTL3 positively regulated CA9 through PBX3. PBX3 deficiency impeded ESCC cell migration and invasion and enhanced cell apoptosis and ferroptosis by downregulating CA9.

CONCLUSION

Our study elucidates a novel mechanism, the METTL3/PBX3/CA9 cascade, underlying the oncogenic activity of METTL3 in ESCC. The novel cascade may represent the potential target for ESCC therapy in the future.

m6A-related genes of peripheral white blood cell in spinal cord injury as potential targets for prognosis and treatment

Objective

Spinal cord injury (SCI) is a destructive neurological and pathological state that causes major motor, sensory, and autonomic dysfunction. N6-methyladenosine (m6A) is a reversible RNA modification implicated in various biological processes. However, few studies have examined m6A expression in patients with SCI. We explored the prognostic value of m6A-related genes as potential biomarkers in SCI to establish a set of accurate diagnostic and prognostic prediction models.

Methods

Differentially expressed analysis and weighted gene co-expression network analysis (WGCNA) was used to explore m6a related modules and hub genes. KEGG and GO analyses was utilized to explore the potential role of these hub genes. Gene expression was verified in single-cell data. The correlation of m6A related gene with spinal cord injury severity was explored.

Results

We found 289 SCI-related and five m6A-related candidate genes with high SCI correlation and high differential expression in the publicly available dataset, GSE151371. These genes are also involved in long-chain fatty acid binding. Early SCI was accompanied by significant immune cell infiltration. Simultaneously, infiltrating immune cells and the innate immune system have a strong cellular interaction, which gradually decreases over time. The number of PPARG-positive cells also increases after SCI. The comparatively higher expression of PPARG and lower expression of AK5 in white blood cells (WBCs) correlates with severity of SCI.

Conclusion

Our integrated analysis illustrates the hub genes involved in SCI, which can be prognostic markers. Further understanding of the functions of the identified SCI hub genes may provide deeper insights into the molecular mechanisms of SCI.

METTL3 obstructs vascular smooth muscle cells osteogenic reprogramming by methylating Runx2 in chronic kidney disease

The reprogrammed osteogenic phenotype of vascular smooth muscle cells (VSMCs) is considered a critical mechanism of vascular calcification (VC) in chronic kidney disease (CKD). Currently, the RNA N6-methyladenosine (m6A) modification is deciphered to be dynamically and reversibly participated in functional regulation of VSMCs. Here, we discover that serum m6A levels in RNA are dramatically reduced as VC progressed in patients with CKD, and this m6A demethylation is mainly due to the downregulation of methyltransferaselike-3 (METTL3). Functionally, METTL3 depletion exacerbates, whereas its overexpression attenuates calcification progression and osteogenic reprogramming. Mechanistically, Runx2, a crucial osteogenic gene, is identified as a key downstream target of METTL3-mediated m6A methylation. METTL3 negatively regulates Runx2 expression through the m6A modification. Overexpression of METTL3 exacerbates Runx2 mRNA degradation, which is orchestrated by the m6A reader YT521-B homology domain family 2 (YTHDF2) through specifically recognizing its m6A sites in the 3'UTR region. Finally, in vivo METTLs inhibitor SAH treatment aggravates VC and osteogenic conversion in aortas of CKD rats, accompanied by Runx2 expression upregulation. These above data reveal an underlying mechanism by which the m6A writer METTL3 regulates Runx2 expression through YTHDF2-mediated mRNA degradation and suggest a potential therapeutic strategy to reverse the osteogenic reprogramming of VSMCs.

Methyltransferase-like 3-mediated RNA N6-methyladenosine contributes to immune dysregulation: diagnostic biomarker and therapeutic target

Methyltransferase-like 3 (METTL3) plays a crucial role in post-transcriptional gene regulation. Substantial evidence links METTL3 to various immune dysfunctions, such as the suppression of antiviral immunity during viral infections and the disruption of immune tolerance in conditions like autoimmune diseases, myeloid leukemia, skin cancers, and anticancer immunotherapy. However, a thorough review and analysis of this evidence is currently missing, which limits the understanding of METTL3's mechanisms and significance in immune dysfunctions. This review aims to elucidate the roles and mechanisms of METTL3 in these immune issues, highlighting its connections and proposing new insights into its modulation of immune responses. Analysis results in this review suggest that METTL3 hampers antiviral immunity, worsens viral replication and infection, and disrupts immune tolerance; conversely, regulating METTL3 enhances antiviral immunity and facilitates viral clearance. Moreover, clinical data corroborates these findings, showing that METTL3 overexpression is associated with increased susceptibility to viral infections and autoimmune conditions. This review establishes a theoretical basis for considering METTL3 as a novel regulator, an important diagnostic biomarker, and a potential target for treating immune dysfunctions.

METTL3 promotes the progression of non-alcoholic fatty liver disease by mediating m6A methylation of FAS

N6-methyladenosine (m6A) is involved in the development of non-alcoholic fatty liver disease (NAFLD). Here, we aimed to investigate the effect of m6A methyltransferase METTL3 on liver damage in high-fat diet (HFD)-induced mouse model and hepatocyte damage treated with free fatty acid (FFA). Plasma lipid, lipogenesis, viability, and apoptosis were measured to assess injury. m6A methylation was evaluated using m6A dot blot, methylated RNA immunoprecipitation, dual-luciferase reporter assay, and RNA decay assay. The results indicated that METTL3 was highly expressed in the liver of HFD mice, which knockdown improved plasma lipid and reduced liver lipids. Additionally, silencing of METTL3 promoted cell viability, inhibited apoptosis, reduced lipid concentrations, and downregulated lipogenesis-related marker levels. Moreover, METTL3 promoted the m6A methylation of FAS and enhanced its stability. In conclusion, silencing of METTL3 attenuates the progression of NAFLD by FAS m6A methylation, suggesting that METTL3 may be a promising target for treating NAFLD.

m1A-regulated DIAPH3 promotes the invasiveness of colorectal cancer via stabilization of KRT19

BACKGROUND

In recent years, the emphasis has shifted to understanding the role of N1-methyladenosine (m1A) in tumor progression as little is known about its regulatory effect on mRNA and its role in the metastasis of colorectal cancer (CRC).

METHODS

We performed methylated RNA immunoprecipitation sequencing of tumor tissues and tumor-adjacent normal tissues from three patients with CRC to determine the m1A profile of mRNA in CRC. The expression of diaphanous-related formin 3 (DIAPH3) and its correlation with clinicopathological characteristics of CRC were evaluated using immunohistochemistry and online datasets. The role of DIAPH3 in the migration and invasion of CRC cells was evaluated using wound healing assay, Transwell assay and xenograft metastatic model. The downstream targets of DIAPH3 were screened using mass spectrometry. By co-transfecting DIAPH3 siRNA and a keratin 19 (KRT19) ectopic plasmid into CRC cells, the role of DIAPH3-KRT19 signaling axis was confirmed.

RESULTS

The mRNA level of DIAPH3 and its m1A modifications increased simultaneously in the CRC tissues. In addition, high DIAPH3 expression in CRC tissues is significantly associated with metastasis and progression to an advanced stage. After the knockdown of DIAPH3, the migration and invasion capabilities of CRC cells suffered a notable decline, which could be rescued by overexpressing KRT19. In addition, the proteasome inhibitor MG132 could block the degradation of KRT19 induced by DIAPH3 silencing.

CONCLUSIONS

Our study reveals that DIAPH3 mRNA was modified in CRC cells by m1A methylation. Silencing DIAPH3 suppresses the migration and invasion of CRC cells, potentially through the proteasome-dependent degradation of downstream KRT19.

COL1A1, mediated by m6A methylation of METTL3, facilitates oral squamous cell carcinoma cell growth and metastasis

Collagen type I alpha1 (COL1A1) has been found to be abnormal expressed in oral squamous cell carcinoma (OSCC) tissues, but its role and mechanism in OSCC need to be further elucidated. The expression levels of COL1A1 and methyltransferase-like 3 (METTL3) were measured by quantitative real-time PCR and western blot. Cell growth and metastasis were determined by CCK8, colony formation, EdU, flow cytometry and transwell assays. MeRIP, Co-IP and dual-luciferase reporter assays were performed to explore the interplay of COL1A1 and METTL3. COL1A1 mRNA stability was confirmed by Actinomycin D assay. Mice xenograft models were constructed to perform in vivo experiments. COL1A1 and METTL3 were upregulated in OSCC. COL1A1 knockdown suppressed OSCC cell growth and metastasis, while its overexpression had an opposite effect. The stability of COL1A1 mRNA was regulated by the m6A methylation of METTL3. METTL3 overexpression promoted OSCC cell growth and metastasis, and its knockdown-mediated OSCC cell function inhibition could be abolished by COL1A1 overexpression. Besides, silencing of METTL3 reduced OSCC tumor growth by reducing COL1A1 expression. METTL3-stabilized COL1A1 promoted OSCC progression, providing an exact molecular target for the treatment of OSCC.

HSYA ameliorates venous thromboembolism by depleting the formation of TLR4/NF-κB pathway-dependent neutrophil extracellular traps

Neutrophil extracellular traps (NETs), released by activated neutrophils, are implicated in various medical conditions, including venous thromboembolism (VTE). To develop effective therapeutic strategies for VTE, it is crucial to elucidate the mechanisms involved. In this study, we explored the role of NETs in VTE pathogenesis and assessed the impact of hydroxyl safflower yellow pigment A (HSYA) treatment on VTE pathogenesis. Various biochemical, pharmacological, and functional assessments were performed in human samples and VTE mouse models. Our findings revealed that NETs formation was enhanced in VTE patients and mouse model. NETs were shown to reduce the viability and integrity of endothelial cells and facilitated ferroptosis in human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. Depletion of NETs using the NE inhibitor Alvelestat significantly alleviated ferroptosis in VTE mice. Similarly, NETs depletion markedly attenuated thrombus formation and vein wall thickness in VTE mice. Notably, NETs treatment induced a significant elevation in total N6-Methyladenosine (m6A) RNA methylation level in HUVECs, with the most significant increase observed in methyltransferase-like 3 (METTL3). Mechanistically, the TLR4/NF-κB pathway was activated, and silencing METTL3 reversed the NETs-induced activation of this pathway in HUVECs. Rescue assays illustrated that METTL3 regulated the viability and ferroptosis of NETs-stimulated HUVECs by mediating TLR4 mRNA stability. Additionally, we found that HSYA exerted protective effects against ferroptosis in NETs-induced HUVECs and VTE mice. In summary, HSYA ameliorates VTE by depleting neutrophil extracellular traps through the inhibition of the TLR4/NF-κB pathway, thus providing a novel therapeutic strategy for treating VTE.

FTO attenuates TNF-α-induced damage of proximal tubular epithelial cells in acute pancreatitis-induced acute kidney injury via targeting AQP3 in an N6-methyladenosine-dependent manner

BACKGROUND

Acute kidney injury (AKI) is a frequent complication of severe acute pancreatitis (SAP). Previous investigations have revealed the involvement of FTO alpha-ketoglutarate-dependent dioxygenase (FTO) and aquaporin 3 (AQP3) in AKI. Therefore, the aim of this study is to explore the association of FTO and AQP3 on proximal tubular epithelial cell damage in SAP-induced AKI.

METHODS

An in-vitro AKI model was established in human proximal tubular epithelial cells (PTECs) HK-2 via tumor necrosis factor-α (TNF-α) induction (20 ng/mL), after which FTO and AQP3 expression was manipulated and quantified by quantitative real-time PCR and Western blotting. The viability and apoptosis of PTECs under various conditions, and reactive oxygen species (ROS), superoxide dismutase (SOD), and malonaldehyde (MDA) levels within these cells were measured using commercial assay kits and flow cytometry. Methylated RNA immunoprecipitation and mRNA stability assays were performed to elucidate the mechanism of FTO-mediated N6-methyladenosine (m6A) modification. Western blotting was performed to quantify β-catenin protein levels in the PTECs.

RESULTS

FTO overexpression attenuated the TNF-α-induced decrease in viability and SOD levels, elevated apoptosis, increased levels of ROS and MDA, and diminished TNF-α-induced AQP3 expression and reduced β-catenin expression, but its silencing led to contradictory results. FTO negatively modulates AQP3 levels in RTECs in an m6A-depednent manner and compromises AQP3 stability. In addition, all FTO overexpression-induced effects in TNF-α-induced PTECs were neutralized following AQP3 upregulation.

CONCLUSION

FTO alleviates TNF-α-induced damage to PTECs in vitro by targeting AQP3 in an m6A-dependent manner.

METTL14 plays an oncogenic role in NSCLC by modulating ferroptosis and the m6A modification of GPX4

CONTEXT

N6-methyladenosine (m6A) of RNA is involved in the progression of non-small cell lung cancer (NSCLC).

OBJECTIVE

This study investigated the role of METTL14 in NSCLC and the mechanism.

MATERIALS AND METHODS

Expression levels were assessed by quantitative real-time PCR and ELISA assays. Cells viability was assessed by cell counting kit-8. M6A methylation was analysed by methylated RNA immunoprecipitation (MeRIP), RIP, luciferase assay, and mRNA stability assay.

RESULTS

The results showed that METTL14 was highly expressed in NSCLC tissues and cell lines. Knockdown of METTL14 inhibited the cell viability while induced ferroptosis of NSCLC cells. Mechanistically, METTL14 interacts with GPX4, mediates m6A modification of GPX4, enhances its mRNA stability, and upregulates its expression. In addition, IGF2BP1 recognises the m6A-methylated GPX4 and mediates the elevated mRNA stability. Moreover, GPX4 reversed the effects of METTL14 depletion.

DISCUSSION AND CONCLUSION

The METTL14/GPX4 axis promotes NSCLC progression by inhibiting cell ferroptosis through the recognition of m6A modification mediated by IGF2BP1.

MiR-124-3p inhibits cell stemness in glioblastoma via targeting EPHA2 through ALKBH5-mediated m6A modification

Glioblastoma (GBM) is the most aggressive form of glioma, characterized by high mortality and poor prognosis. Dysregulation of microRNAs (miRNAs) plays a critical role in the progression and metastasis of GBM. This study aimed to investigate the role and molecular mechanism of miR-124-3p in GBM. Levels of miR-124-3p, EPHA2, and ALKBH5 were measured using quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation, migration, invasion, and stemness were assessed using the Cell Counting Kit-8 (CCK-8), colony formation, Transwell, and sphere formation assays, respectively. Bioinformatics prediction, dual-luciferase reporter assays, and RNA pull-down experiments were employed to validate the target of miR-124-3p. RNA binding protein immunoprecipitation (RIP) and methylated RNA immunoprecipitation (Me-RIP) were utilized to evaluate the regulation of miR-124-3p maturation by ALKBH5. The results indicated that overexpression of miR-124-3p inhibited the proliferation, migration, invasion, and stemness of GBM cells. EPHA2 was identified as a direct downstream target of miR-124-3p, and its overexpression reversed the inhibitory effects of miR-124-3p on cellular functions. Furthermore, miR-124-3p targeted EPHA2 to inactivate the Wnt/β-catenin pathway. Additionally, ALKBH5 negatively regulated miR-124-3p by impeding its processing. In conclusion, knockdown of ALKBH5 promoted the processing of pri-miR-124-3p, increasing mature miR-124-3p levels, which inhibited the malignant behaviors of GBM cells by targeting EPHA2. These findings highlight the importance of the ALKBH5/miR-124-3p/EPHA2 axis in GBM.

The Role of N6-methyladenosine Modification in Gametogenesis and Embryogenesis: Impact on Fertility

The most common epigenetic modification of messenger RNAs (mRNAs) is N6-methyladenosine (m6A), which is mainly located near the 3' untranslated region of mRNAs, near the stop codons, and within internal exons. The biological effect of m6A is dynamically modulated by methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers). By controlling post-transcriptional gene expression, m6A has a significant impact on numerous biological functions, including RNA transcription, translation, splicing, transport, and degradation. Hence, m6A influences various physiological and pathological processes, such as spermatogenesis, oogenesis, embryogenesis, placental function, and human reproductive system diseases. During gametogenesis and embryogenesis, genetic material undergoes significant changes, including epigenomic modifications such as m6A. From spermatogenesis and oogenesis to the formation of an oosperm and early embryogenesis, m6A changes occur at every step. m6A abnormalities can lead to gamete abnormalities, developmental delays, impaired fertilization, and maternal-to-zygotic transition blockage. Both mice and humans with abnormal m6A modifications exhibit impaired fertility. In this review, we discuss the dynamic biological effects of m6A and its regulators on gamete and embryonic development and review the possible mechanisms of infertility caused by m6A changes. We also discuss the drugs currently used to manipulate m6A and provide prospects for the prevention and treatment of infertility at the epigenetic level.

Methyl-Transferase-Like Protein 16 (METTL16): The Intriguing Journey of a Key Epitranscriptomic Player Becoming an Emerging Biological Target

Key epitranscriptomic players have been increasingly characterized for their structural features and their involvement in several diseases. Accordingly, the design and synthesis of novel epitranscriptomic modulators have started opening a glimmer for drug discovery. m6A is a reversible modification occurring on a specific site and is catalyzed by three sets of proteins responsible for opposite functions. Writers (e.g., methyl-transferase-like protein (METTL) 3/METTL14 complex and METTL16) introduce the methyl group on adenosine N-6, by transferring the methyl group from the methyl donor S-adenosyl-methionine (SAM) to the substrate. Despite the rapidly advancing drug discovery progress on METTL3/METTL14, the METTL16 m6A writer has been marginally explored so far. We herein provide the first comprehensive overview of structural and biological features of METTL16, highlighting the state of the art in the field of its biological and structural characterization. We also showcase initial efforts in the identification of structural templates and preliminary structure-activity relationships for METTL16 modulators.

Role of m6A RNA Methylation in Ischemic Stroke

Ischemic stroke is a prominent contributor to global morbidity and mortality rates. The intricate and diverse mechanisms underlying ischemia-reperfusion injury remain poorly comprehended. RNA methylation, an emerging epigenetic modification, plays a crucial role in regulating numerous biological processes, including immunity, DNA damage response, tumorigenesis, metastasis, stem cell renewal, adipocyte differentiation, circadian rhythms, cellular development and differentiation, and cell division. Among the various RNA modifications, N6-methyladenosine (m6A) modification stands as the most prevalent in mammalian mRNA. Recent studies have demonstrated the crucial involvement of m6A modification in the pathophysiological progression of ischemic stroke. This review aims to elucidate the advancements in ischemic stroke-specific investigations pertaining to m6A modification, consolidate the underlying mechanisms implicated in the participation of m6A modification during the onset of ischemic stroke, and deliberate on the potential of m6A modification as a viable therapeutic target for ischemic stroke.

Predicting prognosis and drug sensitivity in bladder cancer: an insight into Pan-programmed cell death patterns regulated by M6A modifications

The team aimed to explore the possible functional significance of M6A regulation in Pan-programmed cell death (PCD) among patients with bladder cancer (BLCA). In BLCA patients, the analysis was conducted on the13 patterns of programmed cell death (PCD) and the regulation of M6A. Transcriptome, genomics, and clinical data were collected from TCGA-BLCA, GEO32548, and IMvigor210. Consensus clustering analysis, functional enrichment analysis, and other prognostic tools were used to validate the Pan-PCD. Finally, in vitro experiments and transcription sequencing were performed to understand the potential influence of the PI3K pathway on Pan-PCD in BLCA patients. Diverse PCD patterns were simultaneously activated, and M6A regulators exhibited significant variability in bladder malignant tissues. The machine learning algorithm established an 8-gene M6A-related Pan-PCD signature. This signature was validated in three independent datasets, and BLCA patients with higher risk scores had worse prognosis. An unsupervised clustering approach identified activated and suppressed Pan-PCD subgroups of BLCA patients, with distinct responses to immunotherapy and drug sensitivity. In addition, the PI3K pathway was identified as a key mechanism for various forms of programmed cell death, encompassing apoptosis, pyroptosis, autophagy, and cell death dependent on lysosomes. This research revealed that the Pan-PCD model was a more promising approach for BLCA patients under M6A regulation. A new signature from M6A-related Pan-PCD was proposed, with prognostic value for survival or drug sensitivity. The PI3K pathway was a key mechanism for multiple PCDs in BLCA patients.

The YTH domain-containing protein family: Emerging players in immunomodulation and tumour immunotherapy targets

BACKGROUND

The modification of N6-methyladenosine (m6A) plays a pivotal role in tumor by altering both innate and adaptive immune systems through various pathways, including the regulation of messenger RNA. The YTH domain protein family, acting as "readers" of m6A modifications, affects RNA splicing, stability, and immunogenicity, thereby playing essential roles in immune regulation and antitumor immunity. Despite their significance, the impact of the YTH domain protein family on tumor initiation and progression, as well as their involvement in tumor immune regulation and therapy, remains underexplored and lacks comprehensive review.

CONCLUSION

This review introduces the molecular characteristics of the YTH domain protein family and their physiological and pathological roles in biological behavior, emphasizing their mechanisms in regulating immune responses and antitumor immunity. Additionally, the review discusses the roles of the YTH domain protein family in immune-related diseases and tumor resistance, highlighting that abnormal expression or dysfunction of YTH proteins is closely linked to tumor resistance.

KEY POINTS

This review provides an in-depth understanding of the YTH domain protein family in immune regulation and antitumor immunity, suggesting new strategies and directions for immunotherapy of related diseases. These insights not only deepen our comprehension of m6A modifications and YTH protein functions but also pave the way for future research and clinical applications.

ZC3H13 promotes ITGA6 m6A modification for chronic obstructive pulmonary disease progression

Chronic obstructive pulmonary disease (COPD) is potentially fatal, and as society ages, its effects on human health are predicted to deteriorate. The potential function of m6A modifications within COPD has become a hot topic recently. This study was conducted to clarify the function and related mechanisms of the m6A methylation transferase ZC3H13 in COPD. The expression of m6A-associated protease and ITGA6 in COPD tissues was assessed using GEO data, qRT-PCR, and western blot. COPD models in cells and mice were established through cigarette smoke extract (CSE) and smoke exposure. Inflammatory marker levels were measured by ELISA, apoptosis by flow cytometry, and mRNA stability with Actinomycin D assay. m6A modification levels were checked by MeRIP-PCR. HE and Masson staining evaluated lung pathology, and alveolar lavage fluid analysis included total cell count and Giemsa staining. ZC3H13 and METTL3 were differentially expressed m6A regulators in COPD, with ZC3H13 being more significantly upregulated. Further analysis revealed the ZC3H13 expression-related differentially expressed genes (DEGs) functions were enriched in the immunoinflammatory pathway, indicating ZC3H13's involvement in COPD pathogenesis through inflammation, and immune responses. Knockdown studies in cellular and mouse models demonstrated ZC3H13's role in exacerbating COPD symptoms, including inflammation, apoptosis, and EMT, and its suppression led to significant improvements. The identification of ITGA6 as a target gene further elucidated the mechanism, showing that ZC3H13 enhances ITGA6 expression and mRNA stability through m6A modification, influencing bronchial epithelial cell inflammation and fibrosis. In conclusion, targeting ZC3H13/ITGA6 could be an underlying therapeutic approach for treating COPD.

Crosstalk between Epigenetics and Metabolic Reprogramming in Metabolic Dysfunction-Associated Steatotic Liver Disease-Induced Hepatocellular Carcinoma: A New Sight

Epigenetic and metabolic reprogramming alterations are two important features of tumors, and their reversible, spatial, and temporal regulation is a distinctive hallmark of carcinogenesis. Epigenetics, which focuses on gene regulatory mechanisms beyond the DNA sequence, is a new entry point for tumor therapy. Moreover, metabolic reprogramming drives hepatocellular carcinoma (HCC) initiation and progression, highlighting the significance of metabolism in this disease. Exploring the inter-regulatory relationship between tumor metabolic reprogramming and epigenetic modification has become one of the hot directions in current tumor metabolism research. As viral etiologies have given way to metabolic dysfunction-associated steatotic liver disease (MASLD)-induced HCC, it is urgent that complex molecular pathways linking them and hepatocarcinogenesis be explored. However, how aberrant crosstalk between epigenetic modifications and metabolic reprogramming affects MASLD-induced HCC lacks comprehensive understanding. A better understanding of their linkages is necessary and urgent to improve HCC treatment strategies. For this reason, this review examines the interwoven landscape of molecular carcinogenesis in the context of MASLD-induced HCC, focusing on mechanisms regulating aberrant epigenetic alterations and metabolic reprogramming in the development of MASLD-induced HCC and interactions between them while also updating the current advances in metabolism and epigenetic modification-based therapeutic drugs in HCC.

YTHDC1 inhibits osteoclast differentiation to alleviate osteoporosis by enhancing PTPN6 messenger RNA stability in an m6A-hUR-dependent manner

YTHDC1 has been confirmed to mediate osteoporosis (OP) progression by regulating osteogenic differentiation. However, whether YTHDC1 mediates osteoclast differentiation and its molecular mechanism remains unclear. Quantitative real-time polymerase chain reaction and Western blot analysis were performed to detect the levels of YTHDC1, PTPN6, NFATc1, TRAP, RUNX2, alkaline phosphatase, and HUR. YTHDC1 knockout mice was constructed by CRISPR/Cas9 system, and the OP mice model was established by ovariectomy. Hematoxylin and eosin staining and micro-computed tomography were used to evaluate bone formation and bone mass. Mouse primary bone marrow macrophage cells were isolated and induced into osteoclasts. TRAP-positive cells were detected using TRAP staining. MeRIP-qPCR, RIP-qPCR assay, RNA affinity isolation assay, and co-immunoprecipitation assay were used to confirm the interactions among YTHDC1, PTPN6, and HUR. YTHDC1 expression was reduced and positively correlated with lumbar bone mineral density in OP patients. In the ovariectomy model of YTHDC1 knockout mice, bone formation was reduced, bone histomorphology was changed, and osteoclastic-related factor (NFATc1 and TRAP) levels were enhanced. Overexpression YTHDC1 inhibited osteoclast differentiation. YTHDC1 increased PTPN6 messenger RNA stability in an m6A-dependent manner. Moreover, YTHDC1 interacted with HUR to positively regulate PTPN6 expression. PTPN6 knockdown promoted osteoclast differentiation, and this effect was reversed by overexpressing HUR or YTHDC1. YTHDC1 was involved in regulating OP progression through inhibiting osteoclast differentiation by enhancing PTPN6 messenger RNA stability in an m6A-HUR-dependent manner.

Micropeptide AF127577.4-ORF hidden in a lncRNA diminishes glioblastoma cell proliferation via the modulation of ERK2/METTL3 interaction

Micropeptides hidden in long non-coding RNAs (lncRNAs) have been uncovered to program various cell-biological changes associated with malignant transformation-glioblastoma (GBM) cascade. Here, we identified and characterized a novel hidden micropeptide implicated in GBM. We screened potential candidate lncRNAs by establishing a workflow involving ribosome-bound lncRNAs, publicly available MS/MS data, and prognosis-related lncRNAs. Micropeptide expression was detected by western blot (WB), immunofluorescence (IF), and immunohistochemistry (IHC). Cell proliferation rate was assessed by calcein/PI staining and EdU assay. Proteins interacted with the micropeptide were analyzed by proteomics after co-immunoprecipitation (Co-IP). We discovered that lncRNA AF127577.4 indeed encoded an endogenous micropeptide, named AF127577.4-ORF. AF127577.4-ORF was associated with GBM clinical grade. In vitro, AF127577.4-ORF could suppress GBM cell proliferation. Moreover, AF127577.4-ORF reduced m6A methylation level of GBM cells. Mechanistically, AF127577.4-ORF diminished ERK2 interaction with m6A reader methyltransferase like 3 (METTL3) and downregulated phosphorylated ERK (p-ERK) level. The ERK inhibitor reduced p-ERK level and downregulated METTL3 protein expression. AF127577.4-ORF weakened the stability of METTL3 protein by ERK. Also, AF127577.4-ORF suppressed GBM cell proliferation via METTL3. Our study identifies a novel micropeptide AF127577.4-ORF hidden in a lncRNA, with a potent anti-proliferating function in GBM by diminishing METTL3 protein stability by reducing the ERK2/METTL3 interaction. This micropeptide may be beneficial for development of therapeutic strategies against GBM.

Decoding the ribosome's hidden language: rRNA modifications as key players in cancer dynamics and targeted therapies

Ribosomal RNA (rRNA) modifications, essential components of ribosome structure and function, significantly impact cellular proteomics and cancer biology. These chemical modifications transcend structural roles, critically shaping ribosome functionality and influencing cellular protein profiles. In this review, the mechanisms by which rRNA modifications regulate both rRNA functions and broader cellular physiological processes are critically discussed. Importantly, by altering the translational output, rRNA modifications can shift the cellular equilibrium towards oncogenesis, thus playing a key role in cancer development and progression. Moreover, a special focus is placed on the functions of mitochondrial rRNA modifications and their aberrant expression in cancer, an area with profound implications yet largely uncharted. Dysregulation in these modifications can lead to metabolic dysfunction and apoptosis resistance, hallmark traits of cancer cells. Furthermore, the current challenges and future perspectives in targeting rRNA modifications are highlighted as a therapeutic approach for cancer treatment. In conclusion, rRNA modifications represent a frontier in cancer research, offering novel insights and therapeutic possibilities. Understanding and harnessing these modifications can pave the way for breakthroughs in cancer treatment, potentially transforming the approach to combating this complex disease.

HNRNPC promotes estrogen receptor-positive breast cancer cell cycle by stabilizing WDR77 mRNA in an m6A-dependent manner

Breast cancer has become the most commonly diagnosed cancer. Heterogeneous nuclear ribonucleoprotein C (HNRNPC), a reader of N6-methyladenosine (m6A), has been observed to be upregulated in various types of cancer. Nevertheless, the role of HNRNPC in breast cancer and whether it is regulated by m6A modification deserve further investigation. The expression of HNRNPC in breast cancer was examined by quantitative real-time polymerase chain reaction and western blot analysis. RNA immunoprecipitation was performed to validate the binding relationships between HNRNPC and WD repeat domain 77 (WDR77). The effects of HNRNPC and m6A regulators on WDR77 were investigated by actinomycin D assay. The experiments in vivo were conducted in xenograft models. In this research, we found that HNRNPC was highly expressed in breast cancer, and played a crucial role in cell growth, especially in the luminal subtype. HNRNPC could combine and stabilize WDR77 mRNA. WDR77 successively drove the G1/S phase transition in the cell cycle and promoted cell proliferation. Notably, this regulation axis was closely tied to the m6A modification status of WDR77 mRNA. Overall, a critical regulatory mechanism was identified, as well as promising targets for potential treatment strategies for luminal breast cancer.

Targeting insulin-like growth factor 2 mRNA-binding proteins (IGF2BPs) for the treatment of cancer

Insulin-like growth factor 2 mRNA-binding proteins (IMPs, IGF2BPs) are RNA-binding proteins that regulate a variety of biological processes. In recent years, several studies have found that IGF2BPs play multiple roles in various biological processes, especially in cancer, and speculated on their mechanism of anticancer effect. In addition, targeting IGF2BPs or their downstream target gene has also received extensive attention as an effective treatment for different types of cancer. In this review, we summarized the recent progress on the role of IGF2BPs in cancers and their structural characteristics. We focused on describing the development of inhibitors targeting IGF2BPs and the prospects for further applications.

Epigenetic modification in liver fibrosis: Promising therapeutic direction with significant challenges ahead

Liver fibrosis, characterized by scar tissue formation, can ultimately result in liver failure. It's a major cause of morbidity and mortality globally, often associated with chronic liver diseases like hepatitis or alcoholic and non-alcoholic fatty liver diseases. However, current treatment options are limited, highlighting the urgent need for the development of new therapies. As a reversible regulatory mechanism, epigenetic modification is implicated in many biological processes, including liver fibrosis. Exploring the epigenetic mechanisms involved in liver fibrosis could provide valuable insights into developing new treatments for chronic liver diseases, although the current evidence is still controversial. This review provides a comprehensive summary of the regulatory mechanisms and critical targets of epigenetic modifications, including DNA methylation, histone modification, and RNA modification, in liver fibrotic diseases. The potential cooperation of different epigenetic modifications in promoting fibrogenesis was also highlighted. Finally, available agonists or inhibitors regulating these epigenetic mechanisms and their potential application in preventing liver fibrosis were discussed. In summary, elucidating specific druggable epigenetic targets and developing more selective and specific candidate medicines may represent a promising approach with bright prospects for the treatment of chronic liver diseases.

N6-methyladenosine modification in ischemic stroke: Functions, regulation, and therapeutic potential

N6-methyladenosine (m6A) modification is the most frequently occurring internal modification in eukaryotic RNAs. By modulating various aspects of the RNA life cycle, it has been implicated in a wide range of pathological and physiological processes associated with human diseases. Ischemic stroke is a major cause of death and disability worldwide with few treatment options and a narrow therapeutic window, and accumulating evidence has indicated the involvement of m6A modifications in the development and progression of this type of stroke. In this review, which provides insights for the prevention and clinical treatment of stroke, we present an overview of the roles played by m6A modification in ischemic stroke from three main perspectives: (1) the association of m6A modification with established risk factors for stroke, including hypertension, diabetes mellitus, hyperlipidemia, obesity, and heart disease; (2) the roles of m6A modification regulators and their functional regulation in the pathophysiological injury mechanisms of stroke, namely oxidative stress, mitochondrial dysfunction, endothelial dysfunction, neuroinflammation, and cell death processes; and (3) the diagnostic and therapeutic potential of m6A regulators in the treatment of stroke.

Comprehensive analysis of m6A modification in lipopolysaccharide-induced acute lung injury in mice

BACKGROUND

N6-Methyladenosine (m6A) methylation is the most prevalent post-transcriptional modification in mRNA, and plays significant roles in various diseases. Nevertheless, the precise functions of m6A modification in the formation of ALI remain unclear. In this study we explore the transcriptome distribution of m6A methylation and its probable roles of in ALI.

METHODS

Lipopolysaccharide (LPS) was utilized to establish an ALI mouse model. Real-time qPCR, Western blotting and m6A dot blot were utilized to assess m6A methylation level and the expression of m6A methylation enzymes. MeRIP-Seq and RNA-seq were utilized to explore differential m6A modifications and differentially expressed genes in ALI mice. The hub genes and enriched pathways were assessed by Real-time qPCR and Western blotting.

RESULTS

Our findings showed that overall m6A methylation level was increased in ALI mice lung tissues, accompanied by lower levels of METTL3 and FTO. Notably, the protein expression of these methylases were different in various cells. There were 772 differently expressed m6A peaks in ALI as compared to the control group, with 316 being hypermethylated and 456 being hypomethylated. GO and KEGG analyses demonstrated these differentially methylated genes were associated with the calcium signaling pathway and cAMP signaling pathway. Furthermore, we identified 50 genes with distinct m6A peaks and mRNA expressions by combined analysis of MeRIP-Seq and RNA-Seq. KEGG analysis also demonstrated that these overlapped genes were closely associated with the calcium signaling pathway, cGMP-PKG signaling pathway, etc. Besides, Western blotting results demonstrated that the protein expression of Fibronectin leucine-rich transmembrane protein 3 (Flrt3) as well as the calcium signaling pathway and cGMP-PKG signaling pathway, increased significantly after ALI.

CONCLUSIONS

m6A modification was paramount in the pathogenesis of ALI, and provided a foundation for the further investigation in the prevention and treatment of ALI.

Epigenetic modification of m6A methylation: Regulatory factors, functions and mechanism in inflammatory bowel disease

Although the exact cause of inflammatory bowel disease (IBD) is still unknown, there is a lot of evidence to support the notion that it results from a combination of environmental factors, immune system issues, gut microbial changes, and genetic susceptibility. In recent years, the role of epigenetics in the pathogenesis of IBD has drawn increasing attention. The regulation of IBD-related immunity, the preservation of the intestinal epithelial barrier, and autophagy are all significantly influenced by epigenetic factors. The most extensive epigenetic methylation modification of mammalian mRNA among them is N6-methyladenosine (m6A). It summarizes the general structure and function of the m6A regulating factors, as well as their complex effects on IBD by regulating the intestinal mucous barrier, intestine mucosal immunity, epidermal cell death, and intestinal microorganisms.This paper provides key insights for the future identification of potential new targets for the diagnosis and treatment of IBD.

Epitranscriptomic modifications in mesenchymal stem cell differentiation: advances, mechanistic insights, and beyond

RNA modifications, known as the "epitranscriptome", represent a key layer of regulation that influences a wide array of biological processes in mesenchymal stem cells (MSCs). These modifications, catalyzed by specific enzymes, often termed "writers", "readers", and "erasers", can dynamically alter the MSCs' transcriptomic landscape, thereby modulating cell differentiation, proliferation, and responses to environmental cues. These enzymes include members of the classes METTL, IGF2BP, WTAP, YTHD, FTO, NAT, and others. Many of these RNA-modifying agents are active during MSC lineage differentiation. This review provides a comprehensive overview of the current understanding of different RNA modifications in MSCs, their roles in regulating stem cell behavior, and their implications in MSC-based therapies. It delves into how RNA modifications impact MSC biology, the functional significance of individual modifications, and the complex interplay among these modifications. We further discuss how these intricate regulatory mechanisms contribute to the functional diversity of MSCs, and how they might be harnessed for therapeutic applications. The review also highlights current challenges and potential future directions in the study of RNA modifications in MSCs, emphasizing the need for innovative tools to precisely map these modifications and decipher their context-specific effects. Collectively, this work paves the way for a deeper understanding of the role of the epitranscriptome in MSC biology, potentially advancing therapeutic strategies in regenerative medicine and MSC-based therapies.

Increased m6A-RNA methylation and demethylase FTO suppression is associated with silica-induced pulmonary inflammation and fibrosis

Silicosis is a severe worldwide occupational hazard, characterized with lung tissue inflammation and irreversible fibrosis caused by crystalline silicon dioxide. As the most common and abundant internal modification of messenger RNAs or noncoding RNAs, N6-methyladenosine (m6A) methylation is dysregulated in the chromic period of silicosis. However, whether m6A modification is involved in the early phase of silica-induced pulmonary inflammation and fibrosis and its specific effector cells remains unknown. In this study, we established a pulmonary inflammation and fibrosis mouse model by silica particles on day 7 and day 28. Then, we examined the global m6A modification level by m6A dot blot and m6A RNA methylation quantification kits. The key m6A regulatory factors were analyzed by RTqPCR, Western blot, and immunohistochemistry (IHC) in normal and silicosis mice. The results showed that the global m6A modification level was upregulated in silicosis lung tissues with the demethylase FTO suppression after silica exposure for 7 days and 28 days. METTL3, METTL14, ALKBH5, and other m6A readers had no obvious differences between the control and silicosis groups. Then, single-cell sequencing analysis revealed that thirteen kinds of cells were recognized in silicosis lung tissues, and the mRNA expression of FTO was downregulated in epithelial cells, endothelial cells, fibroblasts, and monocytes. These results were further confirmed in mouse lung epithelial cells (MLE-12) exposed to silica and in the peripheral blood mononuclear cells of silicosis patients. In conclusion, the high level of global m6A modification in the early stage of silicosis is induced by the downregulation of the demethylase FTO, which may provide a novel target for the diagnosis and treatment of silicosis.

Inhibition of METTL3 alleviated LPS-induced alveolar epithelial cell apoptosis and acute lung injury via restoring neprilysin expression

AIMS

To investigate the role and mechanisms of methyltransferase-like 3 (METTL3) in the pathogenesis of lipopolysaccharide (LPS)-induced acute lung injury (ALI).

MAIN METHODS

LPS intratracheally instillation was applied in alveolar epithelial cell METTL3 conditional knockout (METTL3-CKO) mice and their wild-type littermates. In addition, METTL3 inhibitor STM2457 was used. LPS treatment on mouse lung epithelial 12 (MLE-12) cell was applied to establish an in vitro model of LPS-induced ALI. H&E staining, lung wet-to-dry ratio, and total broncho-alveolar lavage fluid (BALF) concentrations were used to evaluate lung injury. Overall, the m6A level was determined with the m6A RNA Methylation Quantification Kit and dot blot assay. Expression of METTL3 and neprilysin were measured with immunohistochemistry, immunofluorescence, immunofluorescence-fluorescence in situ hybridization, and western blot. Apoptosis was detected with TUNEL, western blot, and flow cytometry. The interaction of METTL3 and neprilysin was determined with RIP-qPCR and MeRIP.

KEY FINDINGS

METTL3 expression and apoptosis were increased in alveolar epithelial cells of mice treated with LPS, and METTL3-CKO or METTL3 inhibitor STM2457 could alleviate apoptosis and LPS-induced ALI. In MLE-12 cells, LPS-Induced METTL3 expression and apoptosis. Knockdown of METTL3 alleviated, while overexpression of METTL3 exacerbated LPS-induced apoptosis. LPS treatment reduced neprilysin expression, the intervention of neprilysin expression negatively regulated apoptosis without affecting METTL3 expression, and mitigated the promoting effect of METTL3 on LPS-induced apoptosis. Additionally, METTL3 could bind to the mRNA of neprilysin, and reduce its expression.

SIGNIFICANCE

Our findings revealed that inhibition of METTL3 could exert anti-apoptosis and ALI-protective effects via restoring neprilysin expression.

The emerging roles of N6-methyladenosine RNA modifications in thyroid cancer

Thyroid cancer (TC) is the most predominant malignancy of the endocrine system, with steadily growing occurrence and morbidity worldwide. Although diagnostic and therapeutic methods have been rapidly developed in recent years, the underlying molecular mechanisms in the pathogenesis of TC remain enigmatic. The N6-methyladenosine(m6A) RNA modification is designed to impact RNA metabolism and further gene regulation. This process is intricately regulated by a variety of regulators, such as methylases and demethylases. Aberrant m6A regulators expression is related to the occurrence and development of TC and play an important role in drug resistance. This review comprehensively analyzes the effect of m6A methylation on TC progression and the potential clinical value of m6A regulators as prognostic markers and therapeutic targets in this disease.

Epitranscriptomics as a New Layer of Regulation of Gene Expression in Skeletal Muscle: Known Functions and Future Perspectives

Epitranscriptomics refers to post-transcriptional regulation of gene expression via RNA modifications and editing that affect RNA functions. Many kinds of modifications of mRNA have been described, among which are N6-methyladenosine (m6A), N1-methyladenosine (m1A), 7-methylguanosine (m7G), pseudouridine (Ψ), and 5-methylcytidine (m5C). They alter mRNA structure and consequently stability, localization and translation efficiency. Perturbation of the epitranscriptome is associated with human diseases, thus opening the opportunity for potential manipulations as a therapeutic approach. In this review, we aim to provide an overview of the functional roles of epitranscriptomic marks in the skeletal muscle system, in particular in embryonic myogenesis, muscle cell differentiation and muscle homeostasis processes. Further, we explored high-throughput epitranscriptome sequencing data to identify RNA chemical modifications in muscle-specific genes and we discuss the possible functional role and the potential therapeutic applications.

The role of N6-methyladenosine modification in rodent models of neuropathic pain: from the mechanism to therapeutic potential

Neuropathic pain (NP) is a common chronic pain condition resulted from lesions or diseases of somatosensory nervous system, but the pathogenesis remains unclear. A growing body of evidence supports the relationship between pathogenesis and N6-methyladenosine (m6A) modifications of RNA. However, studies on the role of m6A modifications in NP are still at an early stage. Elucidating different etiologies is important for understanding the specific pathogenesis of NP. This article provides a comprehensive review on the role of m6A methylation modifications including methyltransferases ("writers"), demethylases ("erasers"), and m6A binding proteins ("readers") in NP models. Further analysis of the pathogenic mechanism relationship between m6A and NP provided novel theoretical and practical significance for clinical treatment of NP.

Comprehensive analysis of N6-methyladenosine-related RNA methylation in the mouse hippocampus after acquired hearing loss

BACKGROUND

The mechanism underlying cognitive impairment after hearing loss (HL) remains unclear. N6-methyladenosine (m6A) is involved in many neurodegenerative diseases; however, its role in cognitive impairment after HL has not yet been investigated. Therefore, we aimed to analyze the m6A modification profile of the mouse hippocampus after HL exposure. A mouse model of neomycin-induced HL was established. An auditory brainstem-response test was utilized for detecting hearing threshold. The passive avoidance test was served as the mean for evaluating cognitive function. The m6A-regulated enzyme expression levels were analyzed by using reverse transcription quantitative real-time polymerase chain reaction and western blot analyses. RNA sequencing (RNA-Seq) and methylated RNA immunoprecipitation sequencing (MeRIP-Seq) were performed with the aim of investigating gene expression differences and m6A modification in the mouse hippocampus.

RESULTS

Neomycin administration induced severe HL in mice. At four months of age, the mice in the HL group showed poorer cognitive performance than the mice in the control group. METTL14, WTAP, and YTHDF2 mRNA levels were downregulated in the hippocampi of HL mice, whereas ALKBH5 and FTO mRNA levels were significantly upregulated. At the protein level, METTL3 and FTO were significantly upregulated. Methylated RNA immunoprecipitation sequencing analysis revealed 387 and 361 m6A hypermethylation and hypomethylation peaks, respectively. Moreover, combined analysis of mRNA expression levels and m6A peaks revealed eight mRNAs with significantly changed expression levels and methylation.

CONCLUSIONS

Our findings revealed the m6A transcriptome-wide profile in the hippocampus of HL mice, which may provide a basis for understanding the association between HL and cognitive impairment from the perspective of epigenetic modifications.

Epigenetics as a determinant of radiation response in cancer

Radiation therapy is a cornerstone of modern cancer treatment. Treatment is based on depositing focal radiation to the tumor to inhibit cell growth, proliferation and metastasis, and to promote the death of cancer cells. In addition, radiation also affects non-tumor cells in the tumor microenvironmental (TME). Radiation resistance of the tumor cells is the most common cause of treatment failure, allowing survival of cancer cell and subsequent tumor growing. Molecular radioresistance comprises genetic and epigenetic characteristics inherent in cancer cells, or characteristics acquired after exposure to radiation. Furthermore, cancer stem cells (CSCs) and non-tumor cells into the TME as stromal and immune cells have a role in promoting and maintaining radioresistant tumor phenotypes. Different regulatory molecules and pathways distinctive of radiation resistance include DNA repair, survival signaling and cell death pathways. Epigenetic mechanisms are one of the most relevant events that occur after radiotherapy to regulate the expression and function of key genes and proteins in the differential radiation-response. This article reviews recent data on the main molecular mechanisms and signaling pathways related to the biological response to radiotherapy in cancer; highlighting the epigenetic control exerted by DNA methylation, histone marks, chromatin remodeling and m6A RNA methylation on gene expression and activation of signaling pathways related to radiation therapy response.

M6A-mediated-upregulation of lncRNA BLACAT3 promotes bladder cancer angiogenesis and hematogenous metastasis through YBX3 nuclear shuttling and enhancing NCF2 transcription

Lymphatic metastasis is recognized as the leading manner of metastasis in bladder cancer (BLCa), but hematogenous metastasis accounts for a majority of cancer-associated deaths. The past two decades have witnessed tremendous attention in long non-coding RNAs (lncRNAs), which are a new hope for the development of targeted drug therapy for metastatic cancers; however, the underlying mechanism of lncRNAs involved in BLCa hematogenous metastasis remains to be elucidated. Here, we identified BLCa-associated transcript 3 (BLACAT3), a lncRNA, which was aberrantly upregulated in BLCa and corelated with poor prognosis of patients with muscle-invasive bladder cancer. Methodologically, m6A epitranscriptomic microarray, RNA sequencing and mass spectrometry (MS) were used to screen the key molecules of the regulatory axis. Functional assays, animal models and clinical samples were used to explore the roles of BLACAT3 in BLCa in vitro and in vivo. Mechanistically, m6A modification contributes to BLACAT3 upregulation by stabilizing RNA structure. BLACAT3 recruits YBX3 to shuttle into the nucleus, synergistically enhances NCF2 transcription, and promotes BLCa angiogenesis and hematogenous metastasis by activating downstream NF-κB signaling. Our findings will develop prognosis prediction tools for BLCa patients and discover novel therapeutic biological targets for metastatic BLCa.

RNA m6A modification in prostate cancer: A new weapon for its diagnosis and therapy

Prostate cancer (PCa) is the most common malignant tumor and the second leading cause of cancer-related mortality in men worldwide. Despite significant advances in PCa therapy, the underlying molecular mechanisms have yet to be fully elucidated. Recently, epigenetic modification has emerged as a key player in tumor progression, and RNA-based N6-methyladenosine (m6A) epigenetic modification was found to be crucial. This review summarizes comprehensive state-of-art mechanisms underlying m6A modification, its implication in the pathogenesis, and advancement of PCa in protein-coding and non-coding RNA contexts, its relevance to PCa immunotherapy, and the ongoing clinical trials for PCa treatment. This review presents potential m6A-based targets and paves a new avenue for diagnosing and treating PCa, providing new guidelines for future related research through a systematic review of previous results.

METTL3 Affects Spinal Cord Neuronal Apoptosis by Regulating Bcl-2 m6A Modifications After Spinal Cord Injury

OBJECTIVE

Spinal cord injury (SCI) is a severe type of neurological trauma. N6-methyladenosine (m6A) modification is one of the most common internal modifications of RNA. The role of METTL3, the predominant methylation enzyme of m6A modification, in SCI remains unclear. This study aimed to investigate the role of methyltransferase METTL3 in SCI.

METHODS

After establishing the oxygen-glucose deprivation (OGD) model of PC12 cells and rat spinal cord hemisection model, we found that the expression of METTL3 and the overall m6A modification level were significantly increased in neurons. The m6A modification was identified on B-cell lymphoma 2 (Bcl-2) messenger RNA (mRNA) by bioinformatics analysis, and m6A-RNA immunoprecipitation and RNA immunoprecipitation. In addition, METTL3 was blocked by the specific inhibitor STM2457 and gene knockdown, and then apoptosis levels were measured.

RESULTS

In different models, we found that the expression of METTL3 and the overall m6A modification level were significantly increased in neurons. After inducing OGD, inhibition of METTL3 activity or expression increased the mRNA and protein levels of Bcl-2, inhibited neuronal apoptosis, and improved neuronal viability in the spinal cord.

CONCLUSION

Inhibition of METTL3 activity or expression can inhibit the apoptosis of spinal cord neurons after SCI through the m6A/Bcl-2 signaling pathway.

Intergenerational impact of dietary protein restriction in dairy ewes on epigenetic marks in the perirenal fat of their suckling lambs

In sheep, nutrition during the prepubertal stage is essential for growth performance and mammary gland development. However, the potential effects of nutrient restriction in a prepuberal stage over the progeny still need to be better understood. Here, the intergenerational effect of maternal protein restriction at prepubertal age (2 months of age) on methylation patterns was evaluated in the perirenal fat of Assaf suckling lambs. In total, 17 lambs from ewes subjected to dietary protein restriction (NPR group, 44% less protein) and 17 lambs from control ewes (C group) were analyzed. These lambs were ranked based on their carcass proportion of perirenal and cavitary fat and classified into HighPCF and LowPCF groups. The perirenal tissue from 4 NPR-LowPCF, 4 NPR-HighPCF, 4 C-LowPCF, and 4 C-HighPCF lambs was subjected to whole-genome bisulfite sequencing and differentially methylated regions (DMRs) were identified. Among other relevant processes, these DMRs were mapped in genes responsible for regulating the transition of brown to white adipose tissue and nonshivering thermoregulation, which might be associated with better adaptation/survival of lambs in the perinatal stage. The current study provides important biological insights about the intergenerational effect on the methylation pattern of an NPR in replacement ewes.

N6-methyladenosine modified LINC00901 promotes pancreatic cancer progression through IGF2BP2/MYC axis

Accumulating evidence indicates that RNA methylation at N6-methyladenosine (m6A) plays an important regulatory role in gene expression and aberrant mRNA m6A modification is often associated with a variety of cancers. However, little is known whether and how m6A-modification impacts long non-coding RNA (lncRNA) and lncRNA-mediated tumorigenesis, particularly in pancreatic ductal adenocarcinoma (PDAC). In the present study, we report that a previously uncharacterized lncRNA, LINC00901, promotes pancreatic cancer cell growth and invasion and moreover, LINC00901 is subject to m6A modification which regulates its expression. In this regard, YTHDF1 serves as a reader for the m6A modified LINC00901 and downregulates the LINC00901 level. Notably, two conserved m6A sites in LINC00901 are critical to the recognition of LINC00901 by YTHDF1. Finally, RNA sequencing (RNA-seq) and gene function analysis revealed that LINC00901 positively regulates MYC through upregulation of IGF2BP2, a known RNA binding protein that can enhance MYC mRNA stability. Together, our results suggest that there is a LINC00901-IGF2BP2-MYC axis through which LINC00901 promotes PDAC progression in an m6A dependent manner.

m6A Modification-Association with Oxidative Stress and Implications on Eye Diseases

Oxidative stress (OS) refers to a state of imbalance between oxidation and antioxidation. OS is considered to be an important factor leading to aging and a range of diseases. The eyes are highly oxygen-consuming organs. Due to its continuous exposure to ultraviolet light, the eye is particularly vulnerable to the impact of OS, leading to eye diseases such as corneal disease, cataracts, glaucoma, etc. The N6-methyladenosine (m6A) modification is the most investigated RNA post-transcriptional modification and participates in a variety of cellular biological processes. In this study, we review the role of m6A modification in oxidative stress-induced eye diseases and some therapeutic methods to provide a relatively overall understanding of m6A modification in oxidative stress-related eye diseases.

METTL3 from Target Validation to the First Small-Molecule Inhibitors: A Medicinal Chemistry Journey

RNA methylation is a critical mechanism for regulating the transcription and translation of specific sequences or for eliminating unnecessary sequences during RNA maturation. METTL3, an RNA methyltransferase that catalyzes the transfer of a methyl group to the N⁶-adenosine of RNA, is one of the key mediators of this process. METTL3 dysregulation may result in the emergence of a variety of diseases ranging from cancer to cardiovascular and neurological disorders beyond contributing to viral infections. Hence, the discovery of METTL3 inhibitors may assist in furthering the understanding of the biological roles of this enzyme, in addition to contributing to the development of novel therapeutics. Through this work, we will examine the existing correlations between METTL3 and diseases. We will also analyze the development, mode of action, pharmacology, and structure-activity relationships of the currently known METTL3 inhibitors. They include both nucleoside and non-nucleoside compounds, with the latter comprising both competitive and allosteric inhibitors.

The Prognostic Value of a lncRNA Risk Model Consists of 9 m6A Regulator-Related lncRNAs in Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver. Although the RNA modification N6-methyladenine (m6A) has been reported to be involved in HCC carcinogenesis, early diagnostic markers and promising personalized therapeutic targets are still lacking. In this study, we identified that 19 m6A regulators and 34 co-expressed lncRNAs were significantly upregulated in HCC samples; based on these factors, we established a prognostic signal of HCC associated with 9 lncRNAs and 19 m6A regulators using LASSO Cox regression analysis. Kaplan-Meier survival estimate revealed correlations between the risk scores and patients' OS in the training and validation dataset. The ROC curve demonstrated that the risk score-based curve has satisfactory prediction efficiency for both training and validation datasets. Multivariate Cox's proportional hazard regression analysis indicated that the risk score was an independent risk factor within the training and validation dataset. In addition, the risk score could distinguish HCC patients from normal non-cancerous samples and HCC samples of different pathological grades. Eventually, 232 mRNAs were co-expressed with these 9 lncRNAs according to GSE101685 and GSE112790; these mRNAs were enriched in cell cycle and cell metabolic activities, drug metabolism, liver disease-related pathways, and some important cancer related pathways such as p53, MAPK, Wnt, RAS and so forth. The expression of the 9 lncRNAs was significantly higher in HCC samples than that in the neighboring non-cancerous samples. Altogether, by using the Consensus Clustering, PCA, ESTIMATE algorithm, LASSO regression model, Kaplan-Meier survival assessment, ROC curve analysis, and multivariate Cox's proportional hazard regression model analysis, we established a prognostic marker consisting of 9 m6A regulator-related lncRNAs that markers may have prognostic and diagnostic potential for HCC.

N6-Methyladenosine Modification and Prognostic Analysis of UBE2K in Hepatocellular Carcinoma: A Potential Target

The treatment of hepatocellular carcinoma (HCC) is still relatively lacking, the prognosis is poor, and the potential mechanism of carcinogenesis has not been thoroughly studied. In this study, Ubiquitin-conjugating enzyme E2K (UBE2K) transcript levels in HCC patients were up-regulated in two databases, GEO and TCGA. External validation was performed using Western blot experiments. Compared to normal liver cells, UBE2K was upregulated in HCC cell lines. The survival curve and prognosis model revealed that the expression of UBE2K was of high prognostic value in patients with HCC. Transwell assay, wound healing assay and sphere formation assay were used to evaluate the effects of knockdown and overexpression of UBE2K on HCC cells. Overexpression of UBE2K promoted the invasion, migration and stemness of HCC cells, while knocking down UBE2K attenuated the invasion, migration and stemness of HCC cells. Then, through a series of functional analysis (GO and KEEG), it was found that UBE2K played an important role in mRNA processing. We speculate that UBE2K may be involved in HCC progression through its own N6-methyladenosine modification. We therefore used a global methylation inhibitor (3-deazaadenosine) to treat HCC cells and found a gradient increase in the mRNA level of UBE2K. Collectively, the results suggest that UBE2K may be a promising molecular target for the treatment of HCC.

Targeting epigenetic regulators for inflammation: Mechanisms and intervention therapy

Emerging evidence indicates that resolution of inflammation is a critical and dynamic endogenous process for host tissues defending against external invasive pathogens or internal tissue injury. It has long been known that autoimmune diseases and chronic inflammatory disorders are characterized by dysregulated immune responses, leading to excessive and uncontrol tissue inflammation. The dysregulation of epigenetic alterations including DNA methylation, posttranslational modifications to histone proteins, and noncoding RNA expression has been implicated in a host of inflammatory disorders and the immune system. The inflammatory response is considered as a critical trigger of epigenetic alterations that in turn intercede inflammatory actions. Thus, understanding the molecular mechanism that dictates the outcome of targeting epigenetic regulators for inflammatory disease is required for inflammation resolution. In this article, we elucidate the critical role of the nuclear factor-κB signaling pathway, JAK/STAT signaling pathway, and the NLRP3 inflammasome in chronic inflammatory diseases. And we formulate the relationship between inflammation, coronavirus disease 2019, and human cancers. Additionally, we review the mechanism of epigenetic modifications involved in inflammation and innate immune cells. All that matters is that we propose and discuss the rejuvenation potential of interventions that target epigenetic regulators and regulatory mechanisms for chronic inflammation-associated diseases to improve therapeutic outcomes.

m6A demethylase FTO renders radioresistance of nasopharyngeal carcinoma via promoting OTUB1-mediated anti-ferroptosis

Radiotherapy is a valid treatment for nasopharyngeal carcinoma (NPC), and radioresistance is the main cause of local NPC treatment failure. However, the underlying mechanisms and valuable markers of radioresistance for NPC remain have not been established. In this study, we observed that the m6A mRNA demethylase fat mass and obesity-associated protein (FTO) was significantly upregulated in radioresistant NPC tissues and cells relative to parental radiosensitive NPC tissues and cells. FTO enhances radioresistance by repressing radiation-induced ferroptosis in NPC. Mechanistically, FTO acts as an m6A demethylase to erase the m6A modification of the OTUB1 transcript and promote the expression of OTUB1, thereby inhibiting the ferroptosis of cells induced by radiation and finally triggering the radiotherapy resistance of NPC. Furthermore, our in vivo experiment results showed that the FTO inhibitor, FB23-2, and the ferroptosis activator, erastin, altered tumor responsiveness to radiotherapy in NPC cell lines and patient-derived xenografts. Our findings reveal, for the first time, that FTO enhances NPC radiotherapy resistance by withstanding radiation-induced ferroptosis, suggesting that FTO may serve as a potential therapeutic target and valuable prognostic biomarker in patients with NPC.

Role of m6A RNA methylation in the development of hepatitis B virus-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common liver malignancy that can be developed from hepatitis B and cirrhosis. Many pathophysiological alterations, including hepatitis B virus (HBV) DNA integration, oxidative stress, cytokine release, telomerase homeostasis, mitochondrial damage, epigenetic modification, and tumor microenvironment, are involved in the biological process from hepatitis B to cirrhosis and HCC. N6-methyladenosine (m6A), as an epitranscriptomic modification of RNAs, can regulate the stability, splicing, degradation, transcription, and translation of downstream target RNAs in HBV and liver cancer cells. m6A regulators (writers, erasers, and readers) play an important role in the pathogenesis of HBV-associated HCC by regulating cell proliferation, apoptosis, migration, autophagy, differentiation, inflammation, angiogenesis, and tumor microenvironment. This review summarizes the current progress of m6A methylation in the molecular mechanisms, biological functions, and potential clinical implications of HBV-associated HCC.

Small-Molecule Ebselen Binds to YTHDF Proteins Interfering with the Recognition of N 6-Methyladenosine-Modified RNAs

YTHDF proteins bind the N 6-methyladenosine (m6A)-modified mRNAs, influencing their processing, stability, and translation. Therefore, the members of this protein family play crucial roles in gene regulation and several physiological and pathophysiological conditions. YTHDF proteins contain a hydrophobic pocket that accommodates the m6A embedded in the RRACH consensus sequence on mRNAs. We exploited the presence of this cage to set up an m6A-competitive assay and performed a high-throughput screen aimed at identifying ligands binding in the m6A pocket. We report the organoselenium compound ebselen as the first-in-class inhibitor of the YTHDF m6A-binding domain. Ebselen, whose interaction with YTHDF proteins was validated via orthogonal assays, cannot discriminate between the binding domains of the three YTHDF paralogs but can disrupt the interaction of the YTHDF m6A domain with the m6A-decorated mRNA targets. X-ray, mass spectrometry, and NMR studies indicate that in YTHDF1 ebselen binds close to the m6A cage, covalently to the Cys412 cysteine, or interacts reversibly depending on the reducing environment. We also showed that ebselen engages YTHDF proteins within cells, interfering with their mRNA binding. Finally, we produced a series of ebselen structural analogs that can interact with the YTHDF m6A domain, proving that ebselen expansion is amenable for developing new inhibitors. Our work demonstrates the feasibility of drugging the YTH domain in YTHDF proteins and opens new avenues for the development of disruptors of m6A recognition.

The Role of N6-Methyladenosine Modification in Microvascular Dysfunction

Microvascular dysfunction (MVD) has long plagued the medical field despite improvements in its prevention, diagnosis, and intervention. Microvascular lesions from MVD increase with age and further lead to impaired microcirculation, target organ dysfunction, and a mass of microvascular complications, thus contributing to a heavy medical burden and rising disability rates. An up-to-date understanding of molecular mechanisms underlying MVD will facilitate discoveries of more effective therapeutic strategies. Recent advances in epigenetics have revealed that RNA methylation, an epigenetic modification, has a pivotal role in vascular events. The N⁶-methylation of adenosine (m⁶A) modification is the most prevalent internal RNA modification in eukaryotic cells, which regulates vascular transcripts through splicing, degradation, translation, as well as translocation, thus maintaining microvascular homeostasis. Conversely, the disruption of the m⁶A regulatory network will lead to MVD. Herein, we provide a review discussing how m⁶A methylation interacts with MVD. We also focus on alterations of the m⁶A regulatory network under pathological conditions. Finally, we highlight the value of m⁶A regulators as prognostic biomarkers and novel therapeutic targets, which might be a promising addition to clinical medicine.

microRNA-145-5p inhibits prostate cancer bone metastatic by modulating the epithelial-mesenchymal transition

Objective

To investigate the effects of miRNA-145-5p on the tumor development and progression of prostate cancer (Pca) bone metastasis.

Methods

Levels of miRNA-145-5p were assessed by real-time quantitative PCR in PC3 (bone metastatic Pca cells), 22RV1 (non-metastatic Pca cells), RWPE-1 (non-cancerous prostate epithelial cells) and Pca tissues collected from patients with and without bone metastases. The impact of miRNA-145-5p on cell proliferation was tested by CCK8 assay, colony formation assay and flow cytometric cell cycle analysis. Effects on invasion and migration of PC3 cells were determined by Transwell and wound healing assays. Western blotting, enzyme-linked immunosorbent assay, and flow cytometry apoptosis analyses were also performed to assess roles in metastasis.

Results

Levels of miRNA-145-5p were decreased in Pca bone metastases and miRNA-145-5p inhibited cell proliferation, migration and invasion. miRNA-145-5p inhibited the expression of basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF) and transforming growth factor-β (TGF-β) in PC3 cells. miR-145-5p increased the expression of the epithelial marker E-cadherin and reduced the expression of matrix metalloproteinase 2 and 9 (MMP-2 and MMP-9). It was found that miRNA-145-5p mediated the epithelial-mesenchymal transition (EMT) and induced apoptosis.

Conclusions

miRNA-145-5p negatively regulated the EMT, inhibited Pca bone metastasis and promoted apoptosis in Pca bone metastasis. Mimicry of miRNA-145-5p action raises the possibility of a novel target for treating Pca with bone metastases.