METTLing in Stem Cell and Cancer Biology

Upregulated m7G methyltransferase METTL1 is a potential biomarker and tumor promoter in skin cutaneous melanoma

The m7G methyltransferase METTL1 has been implicated in the occurrence and progression of several cancers. However, its clinical significance in cutaneous melanoma (SKCM) remains poorly understood. To address this gap, we conducted comprehensive data mining using publicly available datasets and two single-cell datasets. Additionally, we employed CCK8 assays, clone formation assays, and cell migration and invasion experiments to validate our findings from the data mining. Our results revealed that METTL1 is significantly upregulated in SKCM and is associated with a stem cell-like phenotype. Patients with high METTL1 expression exhibited worse prognosis. Furthermore, we identified that the high expression of METTL1 in SKCM is driven by copy number amplification and regulated by the transcription factor MYC. In vitro cellular studies confirmed that METTL1 knockdown significantly inhibited SKCM cell proliferation, clone formation, migration, and invasion. Notably, we observed a strong negative correlation between METTL1 expression and CD8+ T-cell infiltration in SKCM tissues. Moreover, our analysis revealed a significant negative correlation between METTL1 expression levels and the response to immunotherapy in SKCM patients, suggesting that METTL1 may serve as a potential biomarker for predicting immunotherapy response in SKCM. In summary, this study enhances our understanding of the role of m7G RNA modification in tumor progression and highlights METTL1 as a novel therapeutic target and biomarker for SKCM immunotherapy.

Identification of m6A-modified gene signatures in lung adenocarcinoma tumorigenesis and their potential role in drug resistance

BACKGROUND

Lung cancer is one of the most commonly diagnosed cancers. N6-methyladenosine (m6A) modification has a profound impact on RNA translation, splicing, transportation, and stability.

AIMS

This research aimed to identify and verify m6A-modified signatures for Lung adenocarcinoma (LUAD) tumorigenesis.

OBJECTIVE

Our previous mRNA-seq and m6A-seq data from 26 pairs of LUAD samples and tumor-adjacent normal tissues are used.

METHODS

Univariate Cox regression analysis and the least absolute shrinkage and selection operator (LASSO) analysis were used to estimate the significance of 37 collected m6A regulators. WGCNA was constructed to identify the genes correlated with LUAD tumorigenesis. Pearson correlation analysis between mRNA-seq and m6A-seq data was used to identify the m6A-correlation genes.

RESULTS

LASSO-Cox analysis identified 18 m6A significant regulators. The top 3 regulators, including METTL16, FTO, and SRSF10, and their downstream genes which were reported in the literature were analysed to confirm their role in LUAD tumorigenesis. Blue and brown coexpression modules were chosen as key modules for LUAD tumorigenesis. At last, we intersected Lasso-downstream genes, m6A-correlation genes, with blue or brown module genes. As a result, 56 m6A-modified gene signatures were obtained. Among them, AKAP9, PLXNB2, BRPF3, HPS4, EXOC7, and KLF6 have an inconsistent expression in protein and mRNA levels, probably due to m6A modification. In addition, these genes may be involved in regulating drug resistance.

CONCLUSIONS

56 m6A-modified gene signatures for LUAD tumorigenesis were obtained from Pearson correlation analysis between mRNA-seq and m6A-seq data, along with LASSO and WGCNA analysis. Among them, AKAP9, PLXNB2, BRPF3, HPS4, EXOC7 and KLF6 play a crucial role in LUAD tumorigenesis in an m6A modification-dependent manner.

The expression landscape and clinical significance of methyltransferase-like 17 in human cancer and hepatocellular carcinoma: a pan-cancer analysis using multiple databases

BACKGROUND

Methyltransferase-like (METTL) family protein plays a crucial role in the progression of malignancies. However, the function of METTL17 across pan-cancers, especially in hepatocellular carcinoma (HCC) is still poorly understood.

METHODS

All original data were downloaded from TCGA, GTEx, HPA, UCSC databases and various data portals. First, we comprehensively analyzed RNA-seq data from the HPA database of 25 human tissues. An array of bioinformatics methods was employed to explore the potential oncogenic roles of METTL17, including analyzing its related prognosis, mutation, landscapes, tumor stemness index, immune cell infiltration, and other factors among different tumors. Additionally, gene set enrichment analysis (GSEA) was used to analyze pathways associated with METTL17 in HCC. Immunohistochemistry (IHC) was performed on clinical samples to validate the differential expression of METTL17 in HCC and normal tissues. Ultimately, we constructed a METTL17-related risk-score model of HCC and validated its prognostic classification efficiency. Survival rates were calculated using the Kaplan-Meier method. Statistical significance was defined as P < 0.05.

RESULTS

METTL17 was differentially expressed in various cancers. METTL17 maintained strong correlations with the cancer patient's prognosis, genetic alterations, tumor stemness index, and immune-infiltrated cells, etc. In addition, IHC experiments verified that METTL expression was significantly decreased in liver tissues of HCC patients compared to normal liver tissue. GESA analysis indicated METTL17 mainly involves oncogenic and immune-related pathways among HCC. MRPS5, CHCHD2, NCBP1, LRPPRC, DAP3, and BMS1 were included in a prognostic model based on METTL17's interaction networks. Kaplan-Meier survival analysis of the prognostic model showed that the overall survival (OS) of the low-risk group was significantly better than that of the high-risk group (P < 0.001). The area under the receiver operating characteristic (ROC) curve (AUC) of the 1-year, 3-year, and 5-year OS were 0.747, 0.671, and 0.631, respectively.

CONCLUSIONS

METTL17 may serve as a novel prognostic marker and therapeutic target for human tumors, offering a theoretical foundation for formulating more effective and tailored clinical treatment options for cancers, particularly HCC.

METTL14-mediated m6A modification upregulated SOCS3 expression alleviates thyroid cancer progression by regulating the JAK2/STAT3 pathway

Thyroid cancer (TC) is the most common malignant tumor of the head and neck. As a common epigenetic modification in mRNAs, N6-methyladenosine (m6A) modification plays critical roles in biological process of cancers. However, m6A methyltransferase methyltransferase-like 14 (METTL14)-mediated m6A modification and its potential regulatory mechanisms in TC are not fully elucidated. In our study, we observed that METTL14 was decreased in TC tissues and cells. And upregulation of METTL14 induced apoptotic cell death and hampered cell proliferation, epithelial mesenchymal transition (EMT) and tumor growth in vitro and in vivo. Mechanistically, METTL14 increased the expression of suppressor of cytokine signaling 3 (SOCS3) through m6A methylation modification, and knockdown of SOCS3 reversed the inhibitory effect of overexpressing METTL14 on TC tumorigenesis. In addition, METTL14-mediated m6A modification of SOCS3 inactivated the janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) pathway, and in the METTL14-overexpressing TC cells, silencing SOCS3-induced upregulation of cell proliferation, EMT and suppression of apoptosis was reversed by JAK2/STAT3 inhibitor AG490 and WP1066. Together, we indicated that METTL14/m6A/SOCS3/JAK2/STAT3 axis play an important role in the progression of TC.

Decoding the epitranscriptome: a new frontier for cancer therapy and drug resistance

As the role of RNA modification in gene expression regulation and human diseases, the "epitranscriptome" has been shown to be an important player in regulating many physiological and pathological processes. Meanwhile, the phenomenon of cancer drug resistance is becoming more and more frequent, especially in the case of cancer chemotherapy resistance. In recent years, research on relationship between post-transcriptional modification and cancer including drug resistance has become a hot topic, especially the methylation of the sixth nitrogen site of RNA adenosine-m6A (N6-methyladenosine). m6A modification is the most common post-transcriptional modification of eukaryotic mRNA, accounting for 80% of RNA methylation modifications. At the same time, several other modifications of RNA, such as N1-methyladenosine (m1A), 5-methylcytosine (m5C), 3-methylcytosine (m3C), pseudouridine (Ψ) and N7-methylguanosine (m7G) have also been demonstrated to be involved in cancer and drug resistance. This review mainly discusses the research progress of RNA modifications in the field of cancer and drug resistance and targeting of m6A regulators by small molecule modulators, providing reference for future study and development of combination therapy to reverse cancer drug resistance.

METTL protein family: focusing on the occurrence, progression and treatment of cancer

Methyltransferase-like protein is a ubiquitous enzyme-like protein in the human body, with binding domains for nucleic acids, proteins and other small molecules, and plays an important role in a variety of biological behaviours in normal organisms and diseases, characterised by the presence of a methyltransferase-like structural domain and a structurally conserved SAM-binding domain formed by the seven-stranded β-fold structure in the center of the protein. With the deepening of research, the METTL protein family has been found to be abnormally expressed in a variety of tumor diseases, and the clarification of its relationship with tumor diseases can be used as a molecular therapeutic target and has an important role in the prognosis of tumors. In this paper, we review the structure, biological process, immunotherapy, drug-targeted therapy, and markers of the METTL protein family to provide new ideas for the diagnosis and treatment of tumors.

Readers of RNA Modification in Cancer and Their Anticancer Inhibitors

Cancer treatment has always been a challenge for humanity. The inadequacies of current technologies underscore the limitations of our efforts against this disease. Nevertheless, the advent of targeted therapy has introduced a promising avenue, furnishing us with more efficacious tools. Consequently, researchers have turned their attention toward epigenetics, offering a novel perspective in this realm. The investigation of epigenetics has brought RNA readers to the forefront, as they play pivotal roles in recognizing and regulating RNA functions. Recently, the development of inhibitors targeting these RNA readers has emerged as a focal point in research and holds promise for further strides in targeted therapy. In this review, we comprehensively summarize various types of inhibitors targeting RNA readers, including non-coding RNA (ncRNA) inhibitors, small-molecule inhibitors, and other potential inhibitors. We systematically elucidate their mechanisms in suppressing cancer progression by inhibiting readers, aiming to present inhibitors of readers at the current stage and provide more insights into the development of anticancer drugs.

METTL3 shapes m6A epitranscriptomic landscape for successful human placentation

Methyltransferase-like 3 (METTL3), the catalytic enzyme of methyltransferase complex for m6A methylation of RNA, is essential for mammalian development. However, the importance of METTL3 in human placentation remains largely unexplored. Here, we show that a fine balance of METTL3 function in trophoblast cells is essential for successful human placentation. Both loss-of and gain-in METTL3 functions are associated with adverse human pregnancies. A subset of recurrent pregnancy losses and preterm pregnancies are often associated with loss of METTL3 expression in trophoblast progenitors. In contrast, METTL3 is induced in pregnancies associated with fetal growth restriction (FGR). Our loss of function analyses showed that METTL3 is essential for the maintenance of human TSC self-renewal and their differentiation to extravillous trophoblast cells (EVTs). In contrast, loss of METTL3 in human TSCs promotes syncytiotrophoblast (STB) development. Global analyses of RNA m6A modification and METTL3-RNA interaction in human TSCs showed that METTL3 regulates m6A modifications on the mRNA molecules of critical trophoblast regulators, including GATA2, GATA3, TEAD1, TEAD4, WWTR1, YAP1, TFAP2C and ASCL2, and loss of METTL3 leads to depletion of mRNA molecules of these critical regulators. Importantly, conditional deletion of Mettl3 in trophoblast progenitors of an early post-implantation mouse embryo also leads to arrested self-renewal. Hence, our findings indicate that METLL3 is a conserved epitranscriptomic governor in trophoblast progenitors and ensures successful placentation by regulating their self-renewal and dictating their differentiation fate.

Exploring potential developmental origins of common neurodegenerative disorders

In the United States, it is now estimated that 6.7 million people over the age of 65 are afflicted by Alzheimer's disease (AD), over 1 million people are living with Parkinson's disease (PD), and over 200 000 have or are at risk for developing Huntington's disease (HD). All three of these neurodegenerative diseases result in the ultimate death of distinct neuronal subtypes, and it is widely thought that age-related damage is the single biggest contributing factor to this neuronal death. However, recent studies are now suggesting that developmental defects during early neurogenesis could also play a role in the pathology of neurodegenerative diseases. Loss or overexpression of proteins associated with HD, PD, and AD also result in embryonic phenotypes but whether these developmental defects slowly unmask over time and contribute to age-related neurodegeneration remains highly debated. Here, we discuss known links between embryonic neurogenesis and neurodegenerative disorders (including common signaling pathways), potential compensatory mechanisms that could delay presentation of neurodegenerative disorders, and the types of model systems that could be used to study these links in vivo.

Lineage specification in glioblastoma is regulated by METTL7B

Glioblastomas are the most common malignant brain tumors in adults; they are highly aggressive and heterogeneous and show a high degree of plasticity. Here, we show that methyltransferase-like 7B (METTL7B) is an essential regulator of lineage specification in glioblastoma, with an impact on both tumor size and invasiveness. Single-cell transcriptomic analysis of these tumors and of cerebral organoids derived from expanded potential stem cells overexpressing METTL7B reveal a regulatory role for the gene in the neural stem cell-to-astrocyte differentiation trajectory. Mechanistically, METTL7B downregulates the expression of key neuronal differentiation players, including SALL2, via post-translational modifications of histone marks.

Mitochondrial RNA modification-based signature to predict prognosis of lower grade glioma: a multi-omics exploration and verification study

Mitochondrial RNA modification (MRM) plays a crucial role in regulating the expression of key mitochondrial genes and promoting tumor metastasis. Despite its significance, comprehensive studies on MRM in lower grade gliomas (LGGs) remain unknown. Single-cell RNA-seq data (GSE89567) was used to evaluate the distribution functional status, and correlation of MRM-related genes in different cell types of LGG microenvironment. We developed an MRM scoring system by selecting potential MRM-related genes using LASSO regression analysis and the Random Survival Forest algorithm, based on multiple bulk RNA-seq datasets from TCGA, CGGA, GSE16011, and E-MTAB-3892. Analysis was performed on prognostic and immunological features, signaling pathways, metabolism, somatic mutations and copy number variations (CNVs), treatment responses, and forecasting of potential small-molecule agents. A total of 35 MRM-related genes were selected from the literature. Differential expression analysis of 1120 normal brain tissues and 529 LGGs revealed that 22 and 10 genes were upregulated and downregulated, respectively. Most genes were associated with prognosis of LGG. METLL8, METLL2A, TRMT112, and METTL2B were extensively expressed in all cell types and different cell cycle of each cell type. Almost all cell types had clusters related to mitochondrial RNA processing, ribosome biogenesis, or oxidative phosphorylation. Cell-cell communication and Pearson correlation analyses indicated that MRM may promoting the development of microenvironment beneficial to malignant progression via modulating NCMA signaling pathway and ICP expression. A total of 11 and 9 MRM-related genes were observed by LASSO and the RSF algorithm, respectively, and finally 6 MRM-related genes were used to establish MRM scoring system (TRMT2B, TRMT11, METTL6, METTL8, TRMT6, and TRUB2). The six MRM-related genes were then validated by qPCR in glioma and normal tissues. MRM score can predict the malignant clinical characteristics, abundance of immune infiltration, gene variation, clinical outcome, the enrichment of signaling pathways and metabolism. In vitro experiments demonstrated that silencing METTL8 significantly curbs glioma cell proliferation and enhances apoptosis. Patients with a high MRM score showed a better response to immunotherapies and small-molecule agents such as arachidonyl trifluoromethyl ketone, MS.275, AH.6809, tacrolimus, and TTNPB. These novel insights into the biological impacts of MRM within the glioma microenvironment underscore its potential as a target for developing precise therapies, including immunotherapeutic approaches.

Small-molecule inhibition of the METTL3/METTL14 complex suppresses neuroblastoma tumor growth and promotes differentiation

The N6-methyladenosine (m6A) RNA modification is an important regulator of gene expression. m6A is deposited by a methyltransferase complex that includes methyltransferase-like 3 (METTL3) and methyltransferase-like 14 (METTL14). High levels of METTL3/METTL14 drive the growth of many types of adult cancer, and METTL3/METTL14 inhibitors are emerging as new anticancer agents. However, little is known about the m6A epitranscriptome or the role of the METTL3/METTL14 complex in neuroblastoma, a common pediatric cancer. Here, we show that METTL3 knockdown or pharmacologic inhibition with the small molecule STM2457 leads to reduced neuroblastoma cell proliferation and increased differentiation. These changes in neuroblastoma phenotype are associated with decreased m6A deposition on transcripts involved in nervous system development and neuronal differentiation, with increased stability of target mRNAs. In preclinical studies, STM2457 treatment suppresses the growth of neuroblastoma tumors in vivo. Together, these results support the potential of METTL3/METTL14 complex inhibition as a therapeutic strategy against neuroblastoma.

Size-Optimized Layered Double Hydroxide Nanoparticles Promote Neural Progenitor Cells Differentiation of Embryonic Stem Cells Through the Regulation of M6A Methylation

Purpose

The committed differentiation fate regulation has been a difficult problem in the fields of stem cell research, evidence showed that nanomaterials could promote the differentiation of stem cells into specific cell types. Layered double hydroxide (LDH) nanoparticles possess the regulation function of stem cell fate, while the underlying mechanism needs to be investigated. In this study, the process of embryonic stem cells (ESCs) differentiate to neural progenitor cells (NPCs) by magnesium aluminum LDH (MgAl-LDH) was investigated.

Methods

MgAl-LDH with diameters of 30, 50, and 100 nm were synthesized and characterized, and their effects on the cytotoxicity and differentiation of NPCs were detected in vitro. Dot blot and MeRIP-qPCR were performed to detect the level of m6A RNA methylation in nanoparticles-treated cells.

Results

Our work displayed that LDH nanoparticles of three different sizes were biocompatible with NPCs, and the addition of MgAl-LDH could significantly promote the process of ESCs differentiate to NPCs. 100 nm LDH has a stronger effect on promoting NPCs differentiation compared to 30 nm and 50 nm LDH. In addition, dot blot results indicated that the enhanced NPCs differentiation by MgAl-LDH was closely related to m6A RNA methylation process, and the major modification enzyme in LDH controlled NPCs differentiation may be the m6A RNA methyltransferase METTL3. The upregulated METTL3 by LDH increased the m6A level of Sox1 mRNA, enhancing its stability.

Conclusion

This work reveals that MgAl-LDH nanoparticles can regulate the differentiation of ESCs into NPCs by increasing m6A RNA methylation modification of Sox1.

METTL17 coordinates ferroptosis and tumorigenesis by regulating mitochondrial translation in colorectal cancer

Ferroptosis, an iron-dependent lipid peroxidation-induced form of regulated cell death, shows great promise as a cancer therapy strategy. Despite the critical role of mitochondria in ferroptosis regulation, the underlying mechanisms remain elusive. This study reveals that the mitochondrial protein METTL17 governs mitochondrial function in colorectal cancer (CRC) cells through epigenetic modulation. Bioinformatic analysis establishes that METTL17 expression positively correlates with ferroptosis resistance in cancer cells and is up-regulated in CRC. Depletion of METTL17 sensitizes CRC cells to ferroptosis, impairs cell proliferation, migration, invasion, xenograft tumor growth, and AOM/DSS-induced CRC tumorigenesis. Furthermore, suppression of METTL17 disrupts mitochondrial function, energy metabolism, and enhances intracellular and mitochondrial lipid peroxidation and ROS levels during ferroptotic stress. Mechanistically, METTL17 inhibition significantly reduces mitochondrial RNA methylation, including m4C, m5C, m3C, m7G, and m6A, leading to impaired translation of mitochondrial protein-coding genes. Additionally, the interacting proteins associated with METTL17 are essential for mitochondrial gene expression, and their knockdown sensitizes CRC cells to ferroptosis and inhibits cell proliferation. Notably, combined targeting of METTL17 and ferroptosis in a therapeutic approach effectively suppresses CRC xenograft growth in vivo. This study uncovers the METTL17-mediated defense mechanism for cell survival and ferroptosis in mitochondria, highlighting METTL17 as a potential therapeutic target for CRC.

Epigenetic Regulation of CYP72A385-Mediated Metabolic Resistance to Novel Auxin Herbicide Florpyrauxifen-benzyl in Echinochloa crus-galli (L.) P. Beauv

Weed's metabolic resistance to herbicides has undermined the sustainability of herbicides and global food security. Notably, we identified an Echinochloa crus-galli (L.) P. Beauv population (R) that evolved resistance to the never-used florpyrauxifen-benzyl, in which florpyrauxifen-benzyl was metabolized faster than the susceptible E. crus-galli population (S). RNA-seq identified potential metabolism-related genes, EcCYP72A385 and EcCYP85A1, whose expression in yeast exhibited the capacity to degrade florpyrauxifen-benzyl. Region-2 in the EcCYP72A385 promoter showed significant demethylation after florpyrauxifen-benzyl treatment in the R population. DNA methyltransferase inhibitors induce EcCYP72A385 overexpression in the S population and endow it with tolerance to florpyrauxifen-benzyl. Moreover, methyltransferase-like 7A (EcMETTL7A) was overexpressed in the S population and specifically bound to the EcCYP72A385 promoter. Transgenic EcCYP72A385 in Arabidopsis and Oryza sativa L. exhibited resistance to florpyrauxifen-benzyl, whereas EcMETTL7A transgenic plants were sensitive. Overall, EcCYP72A385 is the principal functional gene for conferring resistance to florpyrauxifen-benzyl and is regulated by EcMETTL7A in E. crus-galli.

Intrafamily heterooligomerization as an emerging mechanism of methyltransferase regulation

Protein and nucleic acid methylation are important biochemical modifications. In addition to their well-established roles in gene regulation, they also regulate cell signaling, metabolism, and translation. Despite this high biological relevance, little is known about the general regulation of methyltransferase function. Methyltransferases are divided into superfamilies based on structural similarities and further classified into smaller families based on sequence/domain/target similarity. While members within superfamilies differ in substrate specificity, their structurally similar active sites indicate a potential for shared modes of regulation. Growing evidence from one superfamily suggests a common regulatory mode may be through heterooligomerization with other family members. Here, we describe examples of methyltransferase regulation through intrafamily heterooligomerization and discuss how this can be exploited for therapeutic use.

Methylation of elongation factor 1A by yeast Efm4 or human eEF1A-KMT2 involves a beta-hairpin recognition motif and crosstalks with phosphorylation

Translation elongation factor 1A (eEF1A) is an essential and highly conserved protein required for protein synthesis in eukaryotes. In both Saccharomyces cerevisiae and human, five different methyltransferases methylate specific residues on eEF1A, making eEF1A the eukaryotic protein targeted by the highest number of dedicated methyltransferases after histone H3. eEF1A methyltransferases are highly selective enzymes, only targeting eEF1A and each targeting just one or two specific residues in eEF1A. However, the mechanism of this selectivity remains poorly understood. To reveal how S. cerevisiae elongation factor methyltransferase 4 (Efm4) specifically methylates eEF1A at K316, we have used AlphaFold-Multimer modeling in combination with crosslinking mass spectrometry (XL-MS) and enzyme mutagenesis. We find that a unique beta-hairpin motif, which extends out from the core methyltransferase fold, is important for the methylation of eEF1A K316 in vitro. An alanine mutation of a single residue on this beta-hairpin, F212, significantly reduces Efm4 activity in vitro and in yeast cells. We show that the equivalent residue in human eEF1A-KMT2 (METTL10), F220, is also important for its activity towards eEF1A in vitro. We further show that the eEF1A guanine nucleotide exchange factor, eEF1Bα, inhibits Efm4 methylation of eEF1A in vitro, likely due to competitive binding. Lastly, we find that phosphorylation of eEF1A at S314 negatively crosstalks with Efm4-mediated methylation of K316. Our findings demonstrate how protein methyltransferases can be highly selective towards a single residue on a single protein in the cell.

Structural insights into the specific recognition of mitochondrial ribosome-binding factor hsRBFA and 12 S rRNA by methyltransferase METTL15

Mitochondrial rRNA modifications are essential for mitoribosome assembly and its proper function. The m4C methyltransferase METTL15 maintains mitochondrial homeostasis by catalyzing m4C839 located in 12 S rRNA helix 44 (h44). This modification is essential to fine-tuning the ribosomal decoding center and increasing decoding fidelity according to studies of a conserved site in Escherichia coli. Here, we reported a series of crystal structures of human METTL15-hsRBFA-h44-SAM analog, METTL15-hsRBFA-SAM, METTL15-SAM and apo METTL15. The structures presented specific interactions of METTL15 with different substrates and revealed that hsRBFA recruits METTL15 to mitochondrial small subunit for further modification instead of 12 S rRNA. Finally, we found that METTL15 deficiency caused increased reactive oxygen species, decreased membrane potential and altered cellular metabolic state. Knocking down METTL15 caused an elevated lactate secretion and increased levels of histone H4K12-lactylation and H3K9-lactylation. METTL15 might be a suitable model to study the regulation between mitochondrial metabolism and histone lactylation.

The METTL3/miR-196a Axis Predicts Poor Prognosis in Non-small Cell Lung Cancer

Background: METTL3 accelerates m6A modification to influence cancer progression including non-small cell lung cancer (NSCLC). To illustrate the role and underlying mechanism of METTL3 mediated miR-196a upregulation in NSCLC. Method: The global level of m6A modification was detected by qPCR, western blot and immumohistochemical staining. The TCGA, GEPIA, CPTAC and TIMER databases were used to explore the expression change of METTL3, miR-196a and GAS7 in NSCLC patients. Kaplan-Meier analysis was performed to analyze the prognostic value of miR-196a. NSCLC cells overexpressed or knockdown miR-196a were constructed and used for CCK8, colony formation assay, western blot and immunofluorescence in vitro. The effect of miR-196a on tumor growth was investigated in vivo. Result: We found that METTL3 mediated miR-196a were notably enhancive in NSCLC tissues and in NSCLC cells, which is markedly positively related with the serious TNM stage, the large tumor size, the distant metastasis, and the poor prognosis in patients of NSCLC. Further investigation showed that up-regulated miR-196a promoted cell viability and cell autophagy, while down-regulation of miR-196a revealed opposite results in H1299 and A549 cells. In terms of mechanism, we found that miR-196a interacted with GAS7. In addition, GAS7 expression in NSCLC patients may be positively related with the infiltration of immune cell subsets in tumor microenvironment (TME). Conclusion: The axis of METTL3-miR-196a-GAS7 might be a target for molecular targeted therapy, a potential and novel diagnostic marker for NSCLC patients.

The comprehensive analysis of the prognostic and functional role of N-terminal methyltransferases 1 in pan-cancer

Background

NTMT1, a transfer methylase that adds methyl groups to the N-terminus of proteins, has been identified as a critical player in tumor development and progression. However, its precise function in pan-cancer is still unclear. To gain a more comprehensive understanding of its role in cancer, we performed a thorough bioinformatics analysis.

Methods

To conduct our analysis, we gathered data from multiple sources, including RNA sequencing and clinical data from the TCGA database, protein expression data from the UALCAN and HPA databases, and single-cell expression data from the CancerSEA database. Additionally, we utilized TISIDB to investigate the interaction between the tumor and the immune system. To assess the impact of NTMT1 on the proliferation of SNU1076 cells, we performed a CCK8 assay. We also employed cellular immunofluorescence to detect DNA damage and used flow cytometry to measure tumor cell apoptosis.

Results

Our analysis revealed that NTMT1 was significantly overexpressed in various types of tumors and that high levels of NTMT1 were associated with poor survival outcomes. Functional enrichment analysis indicated that NTMT1 may contribute to tumor development and progression by regulating pathways involved in cell proliferation and immune response. In addition, we found that knockdown of NTMT1 expression led to reduced cell proliferation, increased DNA damage, and enhanced apoptosis in HNSCC cells.

Conclusion

High expression of NTMT1 in tumors is associated with poor prognosis. The underlying regulatory mechanism of NTMT1 in cancer is complex, and it may be involved in both the promotion of tumor development and the inhibition of the tumor immune microenvironment.

RNA modification: mechanisms and therapeutic targets

RNA modifications are dynamic and reversible chemical modifications on substrate RNA that are regulated by specific modifying enzymes. They play important roles in the regulation of many biological processes in various diseases, such as the development of cancer and other diseases. With the help of advanced sequencing technologies, the role of RNA modifications has caught increasing attention in human diseases in scientific research. In this review, we briefly summarized the basic mechanisms of several common RNA modifications, including m6A, m5C, m1A, m7G, Ψ, A-to-I editing and ac4C. Importantly, we discussed their potential functions in human diseases, including cancer, neurological disorders, cardiovascular diseases, metabolic diseases, genetic and developmental diseases, as well as immune disorders. Through the "writing-erasing-reading" mechanisms, RNA modifications regulate the stability, translation, and localization of pivotal disease-related mRNAs to manipulate disease development. Moreover, we also highlighted in this review all currently available RNA-modifier-targeting small molecular inhibitors or activators, most of which are designed against m6A-related enzymes, such as METTL3, FTO and ALKBH5. This review provides clues for potential clinical therapy as well as future study directions in the RNA modification field. More in-depth studies on RNA modifications, their roles in human diseases and further development of their inhibitors or activators are needed for a thorough understanding of epitranscriptomics as well as diagnosis, treatment, and prognosis of human diseases.

Transcriptomic characterization revealed that METTL7A inhibits melanoma progression via the p53 signaling pathway and immunomodulatory pathway

METTL7A is a protein-coding gene expected to be associated with methylation, and its expression disorder is associated with a range of diseases. However, few research have been carried out to explore the relationship between METTL7A and tumor malignant phenotype as well as the involvement potential mechanism. We conducted our research via a combination of silico analysis and molecular biology techniques to investigate the biological function of METTL7A in the progression of cancer. Gene expression and clinical information were extracted from the TCGA database to explore expression variation and prognostic value of METTL7A. In vitro, CCK8, transwell, wound healing and colony formation assays were conducted to explore the biological functions of METT7A in cancer cell. GSEA was performed to explore the signaling pathway involved in METTL7A and validated via western blotting. In conclusion, METTL7A was downregulated in most cancer tissues and its low expression was associated with shorter overall survival. In melanoma, METTL7A downregulation was associated with poorer clinical staging, lower levels of TIL infiltration, higher IC50 levels of chemotherapeutic agents, and poorer immunotherapy outcomes. QPCR results confirm that METTL7A is down-regulated in melanoma cells. Cell function assays showed that METTL7A knockdown promoted proliferation, invasion, migration and clone formation of melanoma cells. Mechanistic studies showed that METTL7A inhibits tumorigenicity through the p53 signaling pathway. Meanwhile, METTL7A is also a potential immune regulatory factor.

Defining the elusive oncogenic role of the methyltransferase TMT1B

Methyltransferases are enzymes fundamental to a wide range of normal biological activities that can become dysregulated during oncogenesis. For instance, the recent description of the methyltransferase-like (METTL) family of enzymes, has demonstrated the importance of the N6-adenosine-methyltransferase (m6A) modification in transcripts in the context of malignant transformation. Because of their importance, numerous METTL family members have been biochemically characterized to identify their cellular substrates, however some members such as METTL7B, recently renamed TMT1B and which is the subject of this review, remain enigmatic. First identified in the stacked Golgi, TMT1B is also localized to the endoplasmic reticulum as well as lipid droplets and has been reported as being upregulated in a wide range of cancer types including lung cancer, gliomas, and leukemia. Interestingly, despite evidence that TMT1B might act on protein substrates, it has also been shown to act on small molecule alkyl thiol substrates such as hydrogen sulfide, and its loss has been found to affect cellular proliferation and migration. Here we review the current evidence for TMT1B's activity, localization, and potential biological role in the context of both normal and cancerous cell types.

Three's a crowd - why did three N-terminal methyltransferases evolve for one job?

N-terminal methylation of the α-amine group (Nα-methylation) is a post-translational modification (PTM) that was discovered over 40 years ago. Although it is not the most abundant of the Nα-PTMs, there are more than 300 predicted substrates of the three known mammalian Nα-methyltransferases, METTL11A and METTL11B (also known as NTMT1 and NTMT2, respectively) and METTL13. Of these ∼300 targets, the bulk are acted upon by METTL11A. Only one substrate is known to be Nα-methylated by METTL13, and METTL11B has no proven in vivo targets or predicted targets that are not also methylated by METTL11A. Given that METTL11A could clearly handle the entire substrate burden of Nα-methylation, it is unclear why three distinct Nα-methyltransferases have evolved. However, recent evidence suggests that many methyltransferases perform important biological functions outside of their catalytic activity, and the Nα-methyltransferases might be part of this emerging group. Here, we describe the distinct expression, localization and physiological roles of each Nα-methyltransferase, and compare these characteristics to other methyltransferases with non-catalytic functions, as well as to methyltransferases with both catalytic and non-catalytic functions, to give a better understanding of the global roles of these proteins. Based on these comparisons, we hypothesize that these three enzymes do not just have one common function but are actually performing three unique jobs in the cell.