LXA4 enhances prostate cancer progression by facilitating M2 macrophage polarization via inhibition of METTL3

METTL3: a multifunctional regulator in diseases

N6-methyladenosine (m6A) methylation is the most prevalent and abundant internal modification of mRNAs and is catalyzed by the methyltransferase complex. Methyltransferase-like 3 (METTL3), the best-known m6A methyltransferase, has been confirmed to function as a multifunctional regulator in the reversible epitranscriptome modulation of m6A modification according to follow-up studies. Accumulating evidence in recent years has shown that METTL3 can regulate a variety of functional genes, that aberrant expression of METTL3 is usually associated with many pathological conditions, and that its expression regulatory mechanism is related mainly to its methyltransferase activity or mRNA posttranslational modification. In this review, we discuss the regulatory functions of METTL3 in various diseases, including metabolic diseases, cardiovascular diseases, and cancer. We focus mainly on recent progress in identifying the downstream target genes of METTL3 and its underlying molecular mechanisms and regulators in the above systems. Studies have revealed that the use of METTL3 as a therapeutic target and a new diagnostic biomarker has broad prospects. We hope that this review can serve as a reference for further studies.

Tumor-associated macrophages remodel the suppressive tumor immune microenvironment and targeted therapy for immunotherapy

Despite the significant advances in the development of immune checkpoint inhibitors (ICI), primary and acquired ICI resistance remains the primary impediment to effective cancer immunotherapy. Residing in the tumor microenvironment (TME), tumor-associated macrophages (TAMs) play a pivotal role in tumor progression by regulating diverse signaling pathways. Notably, accumulating evidence has confirmed that TAMs interplay with various cellular components within the TME directly or indirectly to maintain the dynamic balance of the M1/M2 ratio and shape an immunosuppressive TME, consequently conferring immune evasion and immunotherapy tolerance. Detailed investigation of the communication network around TAMs could provide potential molecular targets and optimize ICI therapies. In this review, we systematically summarize the latest advances in understanding the origin and functional plasticity of TAMs, with a focus on the key signaling pathways driving macrophage polarization and the diverse stimuli that regulate this dynamic process. Moreover, we elaborate on the intricate interplay between TAMs and other cellular constituents within the TME, that is driving tumor initiation, progression and immune evasion, exploring novel targets for cancer immunotherapy. We further discuss current challenges and future research directions, emphasizing the need to decode TAM-TME interactions and translate preclinical findings into clinical breakthroughs. In conclusion, while TAM-targeted therapies hold significant promise for enhancing immunotherapy outcomes, addressing key challenges-such as TAM heterogeneity, context-dependent plasticity, and therapeutic resistance-remains critical to achieving optimal clinical efficacy.

Lipoxin A4 suppresses neutrophil extracellular traps formation through the FPR2-dependent regulation of METTL3 in ischemic stroke

BACKGROUND

This study aimed to clarify whether the neuroprotective effect of LXA4 is associated with the targeting of neutrophil extracellular traps (NETs) in ischemic stroke (IS).

METHODS

The MCAO rat model was established to assess cerebral infarction, brain water content and neurological deficits. ELISA was employed to examine the activities of MPO, NE, MMP-9. RT-qPCR and western blot was performed to analyze molecular expressions. A luciferase reporter assay was performed to measure the effect of EGR1 on the METTL3 promoter. The formation of NETs and cell viability were evaluated using immunofluorescence staining and CCK8 assay, respectively.

RESULTS

LXA4 decreased cerebral infarction and brain water content, improved neurological deficits, and reduced the release of NETs-associated indicators (MPO, NE) in MCAO rats. LXA4 reduced NETs formation, MPO and NE levels in vitro. In addition, LXA4 reduced Fe2 + levels while increasing GPX4, SLC7A11 protein expressions, as well as enhancing cell viability in vitro, suggesting the inhibitory effect of LXA4 on ferroptosis. Notably, METTL3 overexpression produced the opposite effects. Furthermore, the effects of METTL3 overexpression on NETs formation and ferroptosis were partially reversed by LXA4 treatment. The inhibition of METTL3 by LXA4 was found to be dependent on FPR2. In vivo experiments verified that LXA4 inhibited NETs formation through inhibition of METTL3 to alleviate brain injury.

CONCLUSION

This study demonstrates that LXA4 suppresses NETs formation through the FPR2-dependent regulation of METTL3, thereby alleviating brain injury in IS.

Decoding the role of tRNA modifications in cancer progression

Epitranscriptomic modification of tRNA has recently gained traction in the field of cancer biology. The presence of such modifications on tRNA appears to allow for translational control of processes central to progression and malignant transformation. Methyltransferase Like 1 protein (METTL1), along with other epitranscriptomic writers (e.g. NSUN3, NAT10, ELP3, etc.), has recently been investigated in multiple cancer types. Here, we review the impact of such tRNA modifications in tumorigenesis and the progression of cancer toward drug resistance and metastasis. Regulation of central cellular processes relied upon by malignant cancer cells through modulation of the tRNA epitranscriptome represents an area with great potential to bring novel first-in-class therapies to the clinic.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

METTL3 facilitates prostate cancer progression via inducing HOXC6 m6A modification and stabilizing its expression through IGF2BP2-dependent mechanisms

HOXC6 (Homeobox C6) and methyltransferase-like 3 (METTL3) have been shown to be involved in the progression of prostate cancer (PCa). However, whether HOXC6 performs oncogenic effects in PCa via METTL3-mediated N6-methyladenosine (m6A) modification is not yet reported. The Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell, scratch, sphere formation assays were applied for cell growth, invasion, migration and stemness analyses. Glycolysis was evaluated by measuring glucose consumption, lactate generation and ATP/ADP ratio. The N6-methyladenine (m6A) modification profile was determined by RNA immunoprecipitation (Me-RIP) assay. The proteins that interact with PGK1 (phosphoglycerate kinase 1) were confirmed by Co-immunoprecipitation assay. Tumor formation experiments in mice were conducted for in vivo assay. PCa tissues and cells showed highly expressed HOXC6 and METTL3. Functionally, the silencing of HOXC6 or METTL3 suppresses PCa cell proliferation, invasion, migration, stemness, and glycolysis. Moreover, METTL3-induced HOXC6 m6A modification to stabilize its expression. In addition, the m6A reader IGF2BP2 directly recognized and bound to HOXC6 mRNA, and maintained its stability, and was involved in the regulation of HOXC6 expression by METTL3. Furthermore, IGF2BP2 knockdown impaired PCa cell proliferation, invasion, migration, stemness, and glycolysis by regulating HOXC6. Besides that HOXC6 interacted with the glycoytic enzyme PGK1 in PCa cells. In vivo assays further showed that METTL3 silencing reduced the expression of HOXC6 and PGK1, and impeded PCa growth. METTL3 promoted PCa progression by maintaining HOXC6 expression in an m6A-IGF2BP2-dependent mechanism.

Role of N6‑methyladenosine in the pathogenesis, diagnosis and treatment of prostate cancer (Review)

Prostate cancer (PCa) affects males of all racial and ethnic groups, and leads to higher rates of mortality in those belonging to a lower socioeconomic status due to the late detection of the disease. PCa affects middle‑aged males between the ages of 45 and 60 years, and is the highest cause of cancer‑associated mortality in Western countries. As the most abundant and common mRNA modification in higher eukaryotes, N6‑methyladenosine (m6A) is widely distributed in mammalian cells and influences various aspects of mRNA metabolism. Recent studies have found that abnormal expression levels of various m6A regulators significantly affect the development and progression of various types of cancer, including PCa. The present review discusses the influence of m6A regulatory factors on the pathogenesis and progression of PCa through mRNA modification based on the current state of research on m6A methylation modification in PCa. It is considered that the treatment of PCa with micro‑molecular drugs that target the epigenetics of the m6A regulator to correct abnormal m6A modifications is a direction for future research into current diagnostic and therapeutic approaches for PCa.

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

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

Targeting inflammation as cancer therapy

Inflammation has accompanied human beings since the emergence of wounds and infections. In the past decades, numerous efforts have been undertaken to explore the potential role of inflammation in cancer, from tumor development, invasion, and metastasis to the resistance of tumors to treatment. Inflammation-targeted agents not only demonstrate the potential to suppress cancer development, but also to improve the efficacy of other therapeutic modalities. In this review, we describe the highly dynamic and complex inflammatory tumor microenvironment, with discussion on key inflammation mediators in cancer including inflammatory cells, inflammatory cytokines, and their downstream intracellular pathways. In addition, we especially address the role of inflammation in cancer development and highlight the action mechanisms of inflammation-targeted therapies in antitumor response. Finally, we summarize the results from both preclinical and clinical studies up to date to illustrate the translation potential of inflammation-targeted therapies.

The role of N6-methyladenosine in macrophage polarization: A novel treatment strategy for non-alcoholic steatohepatitis

RNA methylation modifications, as a widespread type of modification in eukaryotic cells, especially N6-methyladenosine (m6A), are associated with many activities in organisms, including macrophage polarization and progression of non-alcoholic steatohepatitis (NASH). Macrophages in the liver are of diverse origin and complex phenotype, exhibiting different functions in development of NASH. In the review, we discuss the functions of m6A and m6A-related enzymes in macrophage polarization. Furthermore, we retrospect the role of macrophage polarization in NASH. Finally, we discuss the prospects of m6A in macrophages and NASH, and provide guidance for the treatment of NASH.

Histone methyltransferase SUV39H2 regulates apoptosis and chemosensitivity in prostate cancer through AKT/FOXO signaling pathway

Prostate cancer (PCa) is one of the most common malignant tumors that exhibit both chemoresistance and recurrence. SUV39H2 is highly expressed in many types of human tumors, but its role in the development and progression of PCa has never been clarified. The aim of this study is to elucidate the role of SUV39H2 in the development and progression of PCa, its association with the AKT/FOXO signaling pathway, and its potential implications for PCa diagnosis and treatment. SUV39H2 expression was analyzed in The Cancer Genome Atlas (TCGA) and genotype tissue expression pan-cancer data. The TCGA database was evaluated for SUV39H2 enrichment and its correlation to immune cell infiltration. SUV39H2 levels in PCa tissues and control tissues were determined in 30 patients using qPCR and IHC. Clinical relevance was assessed via The Cancer Genome Atlas (TCGA). In vitro assessments including colony formation assays, Western Blot analysis, CCK-8 assays, and flow cytometry were utilized to establish SUV39H2's contribution to PCa cell growth. The influence of SUV39H2 on PC3 and DU145 cell proliferation was assessed through a cell line-derived xenograft model. Sphere formation assays and qPCR were employed to delineate SUV39H2's role in PCa stemness and chemosensitivity. In vitro macrophage polarization assays provided insights into SUV39H2's association with M2 macrophages, while enrichment analysis shed light on its role in FOXO signaling. PCa tissues expressed higher levels of SUV39H2 than normal tissues. By knocking down SUV39H2, PCa cells were made more chemosensitive to docetaxel and cell proliferation and stemness were inhibited. Additionally, SUV39H2 knockdown significantly inhibited in vivo PCa cell growth and inhibited the polarization of macrophages. Furthermore, SUV39H2 was found to regulate AKT/FOXO signaling by increasing Akt and FOXO3a phosphorylation. Our findings highlight SUV39H2's role in PCa cell apoptosis and chemosensitivity mainly by regulating the AKT/FOXO signaling pathway and suggest that SUV39H2 could be a potential target for PCa diagnosis and treatment.

The role of m6A RNA methylation in autoimmune diseases: Novel therapeutic opportunities

N6-methyladenosine (m6A) modifications, as one of the most common forms of internal RNA chemical modifications in eukaryotic cells, have gained increasing attention in recent years. The m6A RNA modifications exert various crucial roles in various biological processes, such as embryonic development, neurogenesis, circadian rhythms, and tumorigenesis. Recent advances have highlighted that m6A RNA modification plays an important role in immune response, especially in the initiation and progression of autoimmune diseases. In this review, we summarized the regulatory mechanisms of m6A methylation and its biological functions in the immune system and mainly focused on recent progress in research on the potential role of m6A RNA methylation in the pathogenesis of autoimmune diseases, thus providing possible biomarkers and potential targets for the prevention and treatment of autoimmune diseases.

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.

m6A methylation modification and immune cell infiltration: implications for targeting the catalytic subunit m6A-METTL complex in gastrointestinal cancer immunotherapy

N6-methyladenosine (m6A) methylation modification is a ubiquitous RNA modification involved in the regulation of various cellular processes, including regulation of RNA stability, metabolism, splicing and translation. Gastrointestinal (GI) cancers are some of the world's most common and fatal cancers. Emerging evidence has shown that m6A modification is dynamically regulated by a complex network of enzymes and that the catalytic subunit m6A-METTL complex (MAC)-METTL3/14, a core component of m6A methyltransferases, participates in the development and progression of GI cancers. Furthermore, it has been shown that METTL3/14 modulates immune cell infiltration in an m6A-dependent manner in TIME (Tumor immune microenvironment), thereby altering the response of cancer cells to ICIs (Immune checkpoint inhibitors). Immunotherapy has emerged as a promising approach for treating GI cancers. Moreover, targeting the expression of METTL3/14 and its downstream genes may improve patient response to immunotherapy. Therefore, understanding the role of MAC in the pathogenesis of GI cancers and its impact on immune cell infiltration may provide new insights into the development of effective therapeutic strategies for GI cancers.

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.

Emerging role of METTL3 in inflammatory diseases: mechanisms and therapeutic applications

Despite improvements in modern medical therapies, inflammatory diseases, such as atherosclerosis, diabetes, non-alcoholic fatty liver, chronic kidney diseases, and autoimmune diseases have high incidence rates, still threaten human health, and represent a huge financial burden. N6-methyladenosine (m6A) modification of RNA contributes to the pathogenesis of various diseases. As the most widely discussed m6A methyltransferase, the pathogenic role of METTL3 in inflammatory diseases has become a research hotspot, but there has been no comprehensive review of the topic. Here, we summarize the expression changes, modified target genes, and pathogenesis related to METTL3 in cardiovascular, metabolic, degenerative, immune, and infectious diseases, as well as tumors. In addition to epithelial cells, endothelial cells, and fibroblasts, METTL3 also regulates the function of inflammation-related immune cells, including macrophages, neutrophils, dendritic cells, Th17 cells, and NK cells. Regarding therapeutic applications, METTL3 serves as a target for the treatment of inflammatory diseases with natural plant drug components, such as emodin, cinnamaldehyde, total flavonoids of Abelmoschus manihot, and resveratrol. This review focuses on recent advances in the initiation, development, and therapeutic application of METTL3 in inflammatory diseases. Knowledge of the specific regulatory mechanisms involving METTL3 can help to deepen understanding of inflammatory diseases and lay the foundation for the development of precisely targeted drugs to address inflammatory processes.

Methyltransferase-like proteins in cancer biology and potential therapeutic targeting

RNA modification has recently become a significant process of gene regulation, and the methyltransferase-like (METTL) family of proteins plays a critical role in RNA modification, methylating various types of RNAs, including mRNA, tRNA, microRNA, rRNA, and mitochondrial RNAs. METTL proteins consist of a unique seven-beta-strand domain, which binds to the methyl donor SAM to catalyze methyl transfer. The most typical family member METTL3/METTL14 forms a methyltransferase complex involved in N6-methyladenosine (m6A) modification of RNA, regulating tumor proliferation, metastasis and invasion, immunotherapy resistance, and metabolic reprogramming of tumor cells. METTL1, METTL4, METTL5, and METTL16 have also been recently identified to have some regulatory ability in tumorigenesis, and the rest of the METTL family members rely on their methyltransferase activity for methylation of different nucleotides, proteins, and small molecules, which regulate translation and affect processes such as cell differentiation and development. Herein, we summarize the literature on METTLs in the last three years to elucidate their roles in human cancers and provide a theoretical basis for their future use as potential therapeutic targets.

FoxO4 mediates macrophage M2 polarization by promoting LXA4R expression in an ovalbumin-induced allergic asthma model in mice

BACKGROUND

Asthma imposes a heavy burden due to its high prevalence. Forkhead box O4 (FoxO4) proteins participate in the modulation of cell progression. However, the role and mechanism of FoxO4 in asthma remains uncharted.

METHODS

An allergic asthma model was constructed by the induction of ovalbumin and interleukin (IL)-4 in mice and monocyte/macrophage-like Raw264.7 cells, respectively. The role and mechanism of FoxO4 in asthma was determined by pathological staining, immunofluorescence assay, measurement of inflammatory cells in the blood, reverse transcription quantitative polymerase chain reaction (RT-qPCR), Western blot analysis, and flow cytometry.

RESULTS

Ovalbumin treatment triggered an obvious inflammatory cell infiltration with a prominent increase in F4/80⁺ cell numbers. The relative messenger RNA (mRNA) and protein expressions of FoxO4 were increased in both ovalbumin-induced mice and interleukin-4 (IL-4)-induced Raw264.7 cells. Inhibition of FoxO4 via AS1842856 reduced inflammatory cell infiltration, the number of Periodic Acid Schiff+ (PAS+) goblet cells, the numbers of inflammatory cells in the blood, and the airway resistance in ovalbumin-induced mice. Besides, interference of FoxO4 decreased the number of F4/80⁺CD206⁺ cells, and the relative protein expressions of CD163 and Arg1 in vivo and in vitro. Mechanically, suppression of FoxO4 diminished the relative mRNA and protein expressions of LXA4R in both ovalbumin-induced mice and IL-4-induced Raw264.7 cells. Overexpression of LXA4R reversed the outcomes caused by repression of FoxO4, including airway resistance, the number of F4/80+ cells, the proportion of CD206+ cells in ovalbumin-induced mice, and the proportion of F4/80⁺CD206⁺ cells in IL-4-induced Raw264.7 cells.

CONCLUSION

FoxO4/LXA4R axis mediated macrophage M2 polarization in allergic asthma.

The emerging roles and mechanism of N6-methyladenosine (m6A) modifications in urologic tumours progression

Prostate cancer (PCa), bladder cancer (BC), and renal cell cancer (RCC) are the most common urologic tumours in males. N6-methyladenosine (m⁶A), adenosine N6 methylation, is the most prevalent RNA modification in mammals. Increasing evidence suggests that m⁶A plays a crucial role in cancer development. In this review, we comprehensively analyzed the influence of m⁶A methylation on Prostate cancer, bladder cancer, and renal cell cancer and the relationship between the expression of relevant regulatory factors and their development and occurrence, which provides new insights and approaches for the early clinical diagnosis and targeted therapy of urologic malignancies.

The Roles of Tumor-Associated Macrophages in Prostate Cancer

The morbidity of prostate cancer (PCa) is rising year by year, and it has become the primary cause of tumor-related mortality in males. It is widely accepted that macrophages account for 50% of the tumor mass in solid tumors and have emerged as a crucial participator in multiple stages of PCa, with the huge potential for further treatment. Oftentimes, tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) behave like M2-like phenotypes that modulate malignant hallmarks of tumor lesions, ranging from tumorigenesis to metastasis. Several clinical studies indicated that mean TAM density was higher in human PCa cores versus benign prostatic hyperplasia (BPH), and increased biopsy TAM density potentially predicts worse clinicopathological characteristics as well. Therefore, TAM represents a promising target for therapeutic intervention either alone or in combination with other strategies to halt the “vicious cycle,” thus improving oncological outcomes. Herein, we mainly focus on the fundamental aspects of TAMs in prostate adenocarcinoma, while reviewing the mechanisms responsible for macrophage recruitment and polarization, which has clinical translational implications for the exploitation of potentially effective therapies against TAMs.