METTL14-mediated m6A modification of circORC5 suppresses gastric cancer progression by regulating miR-30c-2-3p/AKT1S1 axis

hnRNPU-mediated pathogenic alternative splicing drives gastric cancer progression

BACKGROUND

Alternative splicing (AS) is a process that facilitates the differential inclusion of exonic sequences from precursor messenger RNAs, significantly enhancing the diversity of the transcriptome and proteome. In cancer, pathogenic AS events are closely related to cancer progression. This study aims to investigate the role and regulatory mechanisms of AS in gastric cancer (GC).

METHODS

We analyzed AS events in various tumor samples and identified hnRNPU as a key splicing factor in GC. The effects of hnRNPU on cancer progression were assessed through in vitro and in vivo experiments. Gene knockout models and the FTO inhibitor (meclofenamic acid) were used to validate the interaction between hnRNPU and FTO and their impact on AS.

RESULTS

We found that hnRNPU serves as a key splicing factor in GC, and its high expression is associated with poor clinical prognosis. Genetic depletion of hnRNPU significantly reduced GC progression. Mechanistically, the m6A demethylase FTO interacts with hnRNPU transcripts, decreasing the m6A modification levels of hnRNPU, which leads to exon 14 skipping of the MET gene, thereby promoting GC progression. The FTO inhibitor meclofenamic acid effectively inhibited GC cell growth both in vitro and in vivo.

CONCLUSION

The FTO/hnRNPU axis induces aberrant exon skipping of MET, thereby promoting GC cell growth. Targeting the FTO/hnRNPU axis may interfere with abnormal AS events and provide a potential diagnostic and therapeutic strategy for GC.

METTL14 attenuates cancer stemness by suppressing ATF5/WDR74/β-catenin axis in gastric cancer

Stemness is a key factor contributing to treatment failure in gastric cancer (GC). Methyltransferase-like 14 (METTL14) has been linked to various cancers, though its specific role in regulating stemness in GC remains undefined. In this study, we assessed METTL14 expression levels in GC tissues using public datasets and clinical specimens and investigated its impact on cell proliferation, metastasis, and stemness both in vitro and in vivo. Through m6A RNA immunoprecipitation (MeRIP) and luciferase reporter assays, we identified downstream targets of METTL14. Rescue assays were performed to examine whether METTL14 overexpression could reverse stemness in GC. We also explored the underlying mechanisms using chromatin immunoprecipitation (ChIP) and western blot analysis, focusing on the role of ATF5 and the upstream regulation of METTL14. Our findings show that lower METTL14 expression is associated with poorer overall survival in GC patients. Functionally, METTL14 knockdown enhanced stemness traits in GC cells. Mechanistically, METTL14 facilitated m6A modification, promoting the degradation of ATF5 mRNA. Overexpression of ATF5 reversed the stemness inhibition caused by METTL14 overexpression by increasing WDR74 transcription and enhancing β-catenin nuclear translocation. Furthermore, histone H3 lactylation at Lys18 was found to upregulate METTL14 expression. In conclusion, METTL14 knockdown promotes stemness in GC by mediating m6A modification of ATF5 mRNA, which activates the WDR74/β-catenin axis, making METTL14 a potential therapeutic target for gastric cancer treatment.

FUS and METTL3 collaborate to regulate RNA maturation, preventing unfolded protein response and promoting gastric cancer progression

FUS-mediated alternative splicing and METTL3-regulated RNA methylation play crucial roles in RNA processing. The purpose of this study was to investigate the interactive roles of FUS and METTL3 in gastric cancer (GC) progression. RNA sequencing data were obtained from the TCGA-STAD dataset. Differentially expressed genes (DEGs) were analyzed across groups stratified by the medians of FUS, METTL3, and NEAT1, respectively. Endoplasmic reticulum (ER) stress markers PERK, IRE1, pIRE1, Bip, and CHOP, as well as related apoptosis stress markers PARP, cleaved-PARP, (Cleaved) Caspase 7, and (Cleaved) Caspase 3, were assessed through western blotting. Alternative splicing and N6-methyladenosine (m(6)A) methylation of specific genes were detected with MeRIP-PCR. Finally, in vivo experiments were conducted using nude mice bearing sh-FUS-transfected HGC27 xenograft tumors. FUS and METTL3 expression levels were elevated in GC tissues. A significant overlap of DEGs was observed between the FUS- and METTL3-stratified groups. These overlapping DEGs were predominantly enriched in mRNA processing and protein processing in the ER. ER stress and apoptosis were induced by sh-FUS or sh-METTL3, which was further enhanced by ER stress inducer tunicamycin in both MKN45 and HGC27 cells. Similarly, DEGs for NEAT1 high- and low-expressed groups were enriched in protein processing in the ER and spliceosome. To a lesser extent, ER stress was also induced by sh-NEAT1 and enhanced by tunicamycin in HGC27 cells. Furthermore, sh-FUS or sh-METTL3 influenced alternative splicing and methylation of specific mRNAs, including FUS, NEAT1, PCNA, MCM2, and BIRC5. Tumor progression was inhibited by sh-FUS in mice, and ER stress and apoptosis were induced, which were further enhanced by tunicamycin. FUS and METTL3 collaborate to facilitate RNA maturation. Inhibiting FUS or METTL3 promoted ER stress and apoptosis and inhibited progression in GC.

Mechanisms of METTL14-Mediated m6A Modification in Promoting Iron Overload-Induced Lipid Peroxidative Damage in Vascular Endothelial Cells to Aggravate Atherosclerosis

Atherosclerosis (AS) is a chronic multifactorial disease with damage to vascular endothelial cells (VECs). This study sought to delve into the mechanism of methyltransferase-like 14 (METTL14) in iron overload-induced lipid peroxidative damage in AS. AS mouse model and cell model were established. Levels of METTL14/circRNA coded by the Arhgap12 (circARHGAP12)/Aspartate β-hydroxylase (ASPH) were determined. AS plaque area/lipid deposition/lipid metabolism in AS mice and iron overload in VECs were evaluated. N6-methyladenosine (m6A) level and METTL14 enrichment and human antigen R (HuR) in circARHGAP12 or ASPH were measured. The mRNA stability of circARHGAP12 or ASPH was analyzed. We observed that METTL14 was upregulated in AS mice. METTL14 downregulation reduced plaque area/lipid deposition/iron overload/peroxidative damage in AS mice. In cell models, METTL14 downregulation could VEC injury/iron overload/lipid peroxidative damage. Mechanically, METTL14 increased the stability and expression of circARHGAP12 through m6A modification, further stabilized ASPH mRNA, and promoted ASPH transcription by binding to HuR. Overexpression of circARHGAP12 or inhibition of ASPH averted the protective role of METTL14 downregulation against iron overload-induced peroxidative damage in AS. In conclusion, METTL14-mediated m6A modification upregulated circARHGAP12 and ASPH to aggravate overload-induced lipid peroxidative damage and facilitate AS progression.

Regulation of hsa_circ_0112136 by m6A demethylase FTO can enhance the malignancy of gastric cancer via the regulation of the PI3K/AKT/mTOR pathway

A growing body of research highlights the role that N6-methyladenosine (m6A) modification and circular RNAs (circRNAs) play in gastric cancer (GC) cases. However, studies elucidating the function and mechanism of the recently discovered circRNA hsa_circ_0112136 in GC are limited. This study aimed to examine the pathophysiology of GC progression due to fat mass and obesity-associated protein (FTO)-mediated N6-methyladenosine (m6A) modification of hsa_circ_0112136. The hsa_circ_0112136 and FTO levels in the GC samples were analyzed using qRT-PCR. The Transwell invasion assay, wound healing assay, and CCK8 assays were employed to assess alterations in GC cell invasiveness, migration, and viability due to the aberrant regulation of hsa_circ_0112136 and FTO. Phosphorylated PI3K, AKT, and mTOR (the key proteins of the PI3K/AKT/mTOR pathway) were detected via western blotting after hsa_circ_0112136 suppression. A tumor transplantation mouse model was constructed to evaluate the suppression of hsa_circ_0112136's function in vivo. The correlation among hsa_circ_0112136 and FTO was identified using the MeRIP assay. Levels of hsa_circ_0112136 and FTO were evidently elevated in GC samples. Suppression of has_circ_0112136 reduced the viability, migration, and invasive ability of GC cells in vitro, as well as delayed tumor growth in vivo via suppression of the activation of the PI3K/AKT/mTOR pathway. FTO decreased hsa_circ_0112136 m6A levels and enhanced hsa_circ_0112136 expression. Furthermore, FTO upregulation enhanced GC cell invasion, migration, and survival, which was reversed by hsa_circ_0112136 suppression. Our study proposes that hsa_circ_0112136 functions as a tumor promoter, facilitating the malignant progression of GC through m6A modification (suppressed by FTO) and activating the PI3K/AKT/mTOR pathway. This suggests that targeting FTO-m6A-hsa_circ_0112136-PI3K/AKT/mTOR may be a novel approach for GC intervention.

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.

Analysis of METTL14 expression in pancreatic cancer and adjacent tissues and its prognostic value for patient outcomes

This study aims to analyze the differential expression of METTL14 in pancreatic cancer (PC) tissues and adjacent normal tissues, and its correlation with clinical outcomes. According to the inclusion and exclusion criteria, a total of 80 patients diagnosed in our hospital from January 2021 to January 2023 were chosen as research subjects. RTQ-PCR has detected the mRNA level expression of METTL14 in cancer and para-cancerous tissues. Immunohistochemistry was used to detect the protein expression of METTL14 in cancer and para-cancerous tissues. To compare the relationship between METTL14 expression and clinicopathological parameters in different PC patients. Kaplan-Meier survival analysis of the relationship between METTL14 expression in PC tissues and patient survival prognosis. The Multifactor COX model evaluates factors affecting the prognosis of PC. The expression level of METTL14 mRNA in PC tissues was 5.51 ± 0.35 (kDa), and the positive rate of METTL14 protein expression in PC tissues of all patients was 73.75 (59/80). Tumor location (P = 0.012), tumor differentiation degree (P = 0.028), tumor AJCC stage (P = 0.000), and lymph node metastasis (P = 0.000) were significantly related to the positive rate of METTL14 protein expression in PC tissue. Follow-up results showed that among 80 patients, 63 died. The three-year survival rate of the METTL14 positive group was 13.56% (8/59), and the three-year survival rate of the negative group was 42.86% (9/21). The difference in the three-year survival rate between METTL14 positive and negative expression groups was statistically significant (P = 0.031). Multivariate COX regression analysis results showed that METTL14 was positive (OR 2.797, 95% CI 1.233-5.877), tumor AJCC stage II-III (OR 1.628, 95% CI 1.435-3.859) and lymph node metastasis (OR 1.733, 95% CI 1.122-2.372) were substantive risk factors for poor prognosis in patients with PC. METTL14 expression increases in PC tissue, which is related to tumor AJCC stage, tumor differentiation, and lymph node metastasis, and can be evaluated in the survival prognosis of patients with PC.

The interaction between m6A modification and noncoding RNA in tumor microenvironment on cancer progression

Cancer development is thought to be closely related to aberrant epigenetic regulation, aberrant expression of specific non-coding RNAs (ncRNAs), and tumor microenvironment (TME). The m6A methylation is one of the most abundant RNA modifications found in eukaryotes, and it can determine the fate of RNA at the post-transcriptional level through a variety of mechanisms, which affects important biological processes in the organism. The m6A methylation modification is involved in RNA processing, regulation of RNA nuclear export or localisation, RNA degradation and RNA translation. This process affects the function of mRNAs and ncRNAs, thereby influencing the biological processes of cancer cells. TME accelerates and promotes cancer generation and progression during tumor development. The m6A methylation interacting with ncRNAs is closely linked to TME formation. Mutual regulation and interactions between m6A methylation and ncRNAs in TME create complex networks and mediate the progression of various cancers. In this review, we will focus on the interactions between m6A modifications and ncRNAs in TME, summarising the molecular mechanisms by which m6A interacts with ncRNAs to affect TME and their roles in the development of different cancers. This work will help to deepen our understanding of tumourigenesis and further explore new targets for cancer therapy.

ETS1 and RBPJ transcriptionally regulate METTL14 to suppress TGF-β1-induced epithelial-mesenchymal transition in human bronchial epithelial cells

Asthma is a chronic respiratory disease characterized by airway inflammation and remodeling. Epithelial-mesenchymal transition (EMT) of bronchial epithelial cells is considered to be a crucial player in asthma. Methyltransferase-like 14 (METTL14), an RNA methyltransferase, is implicated in multiple pathological processes, including EMT, cell proliferation and migration. However, the role of METTL14 in asthma remains uncertain. This research aimed to explore the biological functions of METTL14 in asthma and its underlying upstream mechanisms. METTL14 expression was down-regulated in asthmatic from three GEO datasets (GSE104468, GSE165934, and GSE74986). Consistent with this trend, METTL14 was decreased in the lung tissues of OVA-induced asthmatic mice and transforming growth factor-β1 (TGF-β1)-stimulated human bronchial epithelial cells (Beas-2B) in this study. Overexpression of METTL14 caused reduction in mesenchymal markers (FN1, N-cad, Col-1 and α-SMA) in TGF-β1-treated cells, but caused increase in epithelial markers (E-cad), thus inhibiting EMT. Also, METTL14 suppressed the proliferation and migration ability of TGF-β1-treated Beas-2B cells. Two transcription factors, ETS1 and RBPJ, could both bind to the promoter region of METTL14 and drive its expression. Elevating METTL14 expression could reversed EMT, cell proliferation and migration promoted by ETS1 or RBPJ deficiency. These results indicate that the ETS1/METTL14 and RBPJ/METTL14 transcription axes exhibit anti-EMT, anti-proliferation and anti-migration functions in TGF-β1-induced bronchial epithelial cells, implying that METTL14 may be considered an alternative candidate target for the treatment of asthma.

Dynamic RNA methylation modifications and their regulatory role in mammalian development and diseases

Among over 170 different types of chemical modifications on RNA nucleobases identified so far, RNA methylation is the major type of epitranscriptomic modifications existing on almost all types of RNAs, and has been demonstrated to participate in the entire process of RNA metabolism, including transcription, pre-mRNA alternative splicing and maturation, mRNA nucleus export, mRNA degradation and stabilization, mRNA translation. Attributing to the development of high-throughput detection technologies and the identification of both dynamic regulators and recognition proteins, mechanisms of RNA methylation modification in regulating the normal development of the organism as well as various disease occurrence and developmental abnormalities upon RNA methylation dysregulation have become increasingly clear. Here, we particularly focus on three types of RNA methylations: N6-methylcytosine (m6A), 5-methylcytosine (m5C), and N7-methyladenosine (m7G). We summarize the elements related to their dynamic installment and removal, specific binding proteins, and the development of high-throughput detection technologies. Then, for a comprehensive understanding of their biological significance, we also overview the latest knowledge on the underlying mechanisms and key roles of these three mRNA methylation modifications in gametogenesis, embryonic development, immune system development, as well as disease and tumor progression.

Influence of RNA Methylation on Cancerous Cells: A Prospective Approach for Alteration of In Vivo Cellular Composition

RNA methylation is a dynamic and ubiquitous post-transcriptional modification that plays a pivotal role in regulating gene expression in various conditions like cancer, neurological disorders, cardiovascular diseases, viral infections, metabolic disorders, and autoimmune diseases. RNA methylation manifests across diverse RNA species including messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA), exerting pivotal roles in gene expression regulation and various biological phenomena. Aberrant activity of writer, eraser, and reader proteins enables dysregulated methylation landscape across diverse malignancy transcriptomes, frequently promoting cancer pathogenesis. Numerous oncogenic drivers, tumour suppressors, invasion/metastasis factors, and signalling cascade components undergo methylation changes that modulate respective mRNA stability, translation, splicing, transport, and protein-RNA interactions accordingly. Functional studies confirm methylation-dependent alterations drive proliferation, survival, motility, angiogenesis, stemness, metabolism, and therapeutic evasion programs systemically. Methyltransferase overexpression typifies certain breast, liver, gastric, and other carcinomas correlating with adverse clinical outcomes like diminished overall survival. Mapping efforts uncover nodal transcripts for targeted drug development against hyperactivated regulators including METTL3. Some erasers and readers also suitable lead candidates based on apparent synthetic lethality. Proteomic screens additionally highlight relevant methylation-sensitive effector pathways amenable to combinatorial blockade, reversing compensatory signalling mechanisms that facilitate solid tumour progression. Quantifying global methylation burdens and responsible enzymes clinically predicts patient prognosis, risk stratification for adjuvant therapy, and overall therapeutic responsiveness.

The role of m6A modified circ0049271 induced by MNNG in precancerous lesions of gastric cancer

Gastric cancer (GC) is a malignant cancer with the highest global rates of morbidity and death. Dietary factors have a close relationship with the occurrence of GC. Circular RNAs (circRNAs) and N6-methyladenine (m6A) are important factors in the onset and progression of GC and other malignancies. However, little is known about the role of circRNA m6A modifications in the occurrence and development of GC. Initially, a transformed malignant cell model generated by the chemical carcinogen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was established in this investigation. Furthermore, following exposure to MNNG, circ0049271 is substantially expressed in gastric epithelial cells (GES-1). Subsequent research revealed that the knockdown of circ0049271 prevented the epithelial-mesenchymal transition (EMT) as well as the migration, invasion, and proliferation of gastric epithelial cells induced by long-term exposure to MNNG. The opposite effects were observed when circ0049271 was overexpressed. Mechanistically, circ0049271 activates the TGFβ/SMAD signaling pathway and has m6A modifications mediated by WTAP. Our findings indicate that circ0049271 promotes the occurrence of GC by regulating the TGFβ/SMAD pathway, and WTAP may mediate the methylation of circ0049271 m6A. This study provides new insights into the regulation of circRNA-mediated m6A modifications and the discovery of early GC induced by dietary factors such as nitrite.

Circular RNA in Cardiovascular Diseases: Biogenesis, Function and Application

Cardiovascular diseases pose a significant public health challenge globally, necessitating the development of effective treatments to mitigate the risk of cardiovascular diseases. Recently, circular RNAs (circRNAs), a novel class of non-coding RNAs, have been recognized for their role in cardiovascular disease. Aberrant expression of circRNAs is closely linked with changes in various cellular and pathophysiological processes within the cardiovascular system, including metabolism, proliferation, stress response, and cell death. Functionally, circRNAs serve multiple roles, such as acting as a microRNA sponge, providing scaffolds for proteins, and participating in protein translation. Owing to their unique properties, circRNAs may represent a promising biomarker for predicting disease progression and a potential target for cardiovascular drug development. This review comprehensively examines the properties, biogenesis, and potential mechanisms of circRNAs, enhancing understanding of their role in the pathophysiological processes impacting cardiovascular disease. Furthermore, the prospective clinical applications of circRNAs in the diagnosis, prognosis, and treatment of cardiovascular disease are addressed.

Anticancer effects of Erzhimaoling decoction in high-grade serous ovarian cancer in vitro and in vivo

BACKGROUND

High-grade serous ovarian cancer (HGSOC) is a common gynecologic malignancy with a poor prognosis. The traditional Chinese medicine formula Erzhimaoling decoction (EZMLD) has anticancer potential. This study aims to elucidate the anticancer effects of EZMLD on HGSOC in vitro and in vivo.

MATERIALS AND METHODS

EZMLD-containing serum was prepared from Sprague-Dawley rats for treating SKOV3 ovarian cancer cells at varying concentrations for 24 h and 48 h to determine the IC50. Concentrations of 0%, 5%, and 10% for 24 h were chosen for subsequent in vitro experiments. The roles of METTL3 and METTL14 in SKOV3 cells were explored by overexpressing these genes and combining EZMLD with METTL3/14 knockdown. Investigations focused on cell viability and apoptosis, apoptosis-related protein expression, and KRT8 mRNA m6A modification. For in vivo studies, 36 BALB/c nude mice were divided into six groups involving EZMLD (6.75, 13.5, and 27 g/kg) and METTL3 or METTL14 knockdowns, with daily EZMLD gavage for two weeks.

RESULTS

In vitro, EZMLD-containing serum had IC50 values of 8.29% at 24 h and 5.95% at 48 h in SKOV3 cells. EZMLD-containing serum decreased SKOV3 cell viability and increased apoptosis. EZMLD upregulated METTL3/14 and FAS-mediated apoptosis proteins, while downregulating Keratin 8 (KRT8). EZMLD increased KRT8 mRNA m6A methylation. METTL3/14 overexpression reduced SKOV3 cell viability and increased apoptosis, while METTL3/14 knockdown mitigated EZMLD's effects. In vivo, EZMLD suppressed SKOV3 xenografts growth, causing significant apoptosis and modulating protein expression.

CONCLUSIONS

EZMLD has therapeutic potential for ovarian cancer and may be considered for other cancer types. Future research may explore its broader effects beyond cell apoptosis.

Circular RNA circESYT2 serves as a microRNA-665 sponge to promote the progression of hepatocellular carcinoma through ENO2

Circular RNAs (circRNAs) have emerged as crucial regulators in tumor progression, yet their specific role in hepatocellular carcinoma (HCC) remains largely uncharacterized. In this study, we utilized high-transcriptome sequencing to identify the upregulation of circESYT2 (hsa_circ_002142) in HCC tissues. Functional experiments carried out in vivo and in vitro revealed that circESYT2 played a significant role in maintaining the growth and metastatic behaviors of HCC. Through integrative analysis, we identified enolase 2 (ENO2) as a potential target regulated by circESYT2 through the competitive endogenous RNA sponge mechanism. Additional gain- or loss-of-function experiments indicated that overexpression of circESYT2 led to a tumor-promoting effect, which could be reversed by transfection of microRNA-665 (miR-665) mimic or ENO2 knockdown in HCC cells. Furthermore, the direct interaction between miR-665 and circESYT2 and between miR-665 and ENO2 was confirmed using RNA immunoprecipitation, FISH, RNA pull-down, and dual-luciferase reporter assays, highlighting the involvement of the circESYT2/miR-665/ENO2 axis in promoting HCC progression. These findings shed light on the molecular characteristics of circESYT2 in HCC tissues and suggest its potential as a biomarker or therapeutic target for HCC treatment.

N6-methyladenosine modified circPAK2 promotes lymph node metastasis via targeting IGF2BPs/VEGFA signaling in gastric cancer

Circular RNAs (circRNAs) have emerged as key regulators of cancer occurrence and progression, as well as promising biomarkers for cancer diagnosis and prognosis. However, the potential mechanisms of circRNAs implicated in lymph node (LN) metastasis of gastric cancer remain unclear. Herein, we identify a novel N6-methyladenosine (m6A) modified circRNA, circPAK2, which is significantly upregulated in gastric cancer tissues and metastatic LN tissues. Functionally, circPAK2 enhances the migration, invasion, lymphangiogenesis, angiogenesis, epithelial-mesenchymal transition (EMT), and metastasis of gastric cancer in vitro and in vivo. Mechanistically, circPAK2 is exported by YTH domain-containing protein 1 (YTHDC1) from the nucleus to the cytoplasm in an m6A methylation-dependent manner. Moreover, increased cytoplasmic circPAK2 interacts with Insulin-Like Growth Factor 2 mRNA-Binding Proteins (IGF2BPs) and forms a circPAK2/IGF2BPs/VEGFA complex to stabilize VEGFA mRNA, which contributes to gastric cancer vasculature formation and aggressiveness. Clinically, high circPAK2 expression is positively associated with LN metastasis and poor prognosis in gastric cancer. This study highlights m6A-modified circPAK2 as a key regulator of LN metastasis of gastric cancer, thus supporting circPAK2 as a promising therapeutic target and prognostic biomarker for gastric cancer.

Helicobacter Pylori-Enhanced hnRNPA2B1 Coordinates with PABPC1 to Promote Non-m6A Translation and Gastric Cancer Progression

Helicobacter pylori (H. pylori) infection is the primary risk factor for the pathogenesis of gastric cancer (GC). N6-methyladenosine (m6A) plays pivotal roles in mRNA metabolism and hnRNPA2B1 as an m6A reader is shown to exert m6A-dependent mRNA stabilization in cancer. This study aims to explore the role of hnRNPA2B1 in H. pylori-associated GC and its novel molecular mechanism. Multiple datasets and tissue microarray are utilized for assessing hnRNPA2B1 expression in response to H. pylori infection and its clinical prognosis in patients with GC. The roles of hnRNPA2B1 are investigated through a variety of techniques including glucose metabolism analysis, m6A-epitranscriptomic microarray, Ribo-seq, polysome profiling, RIP-seq. In addition, hnRNPA2B1 interaction with poly(A) binding protein cytoplasmic 1 (PABPC1) is validated using mass spectrometry and co-IP. These results show that hnRNPA2B1 is upregulated in GC and correlated with poor prognosis. H. pylori infection induces hnRNPA2B1 upregulation through recruiting NF-κB to its promoter. Intriguingly, cytoplasm-anchored hnRNPA2B1 coordinated PABPC1 to stabilize its relationship with cap-binding eIF4F complex, which facilitated the translation of CIP2A, DLAT and GPX1 independent of m6A modification. In summary, hnRNPA2B1 facilitates the non-m6A translation of epigenetic mRNAs in GC progression by interacting with PABPC1-eIF4F complex and predicts poor prognosis for patients with GC.

RNA epigenetic modifications in digestive tract cancers: Friends or foes

Digestive tract cancers are among the most common malignancies worldwide and have high incidence and mortality rates. Thus, the discovery of more effective diagnostic and therapeutic targets is urgently required. The development of technologies to accurately detect RNA modification has led to the identification of numerous RNA chemical modifications in humans (epitranscriptomics) that are involved in the occurrence and development of digestive tract cancers. RNA modifications can cooperatively regulate gene expression to facilitate normal physiological functions of the digestive system. However, the dysfunction of relevant RNA-modifying enzymes ("writers," "erasers," and "readers") can lead to the development of digestive tract cancers. Consequently, targeting dysregulated enzyme activity could represent a potent therapeutic strategy for the treatment of digestive tract cancers. In this review, we summarize the most widely studied roles and mechanisms of RNA modifications (m6A, m1A, m5C, m7G, A-to-I editing, pseudouridine [Ψ]) in relation to digestive tract cancers, highlight the crosstalk between RNA modifications, and discuss their roles in the interactions between the digestive system and microbiota during carcinogenesis. The clinical significance of novel therapeutic methods based on RNA-modifying enzymes is also discussed. This review will help guide future research into digestive tract cancers that are resistant to current therapeutics.

METTL14 inhibits the proliferation, migration and invasion of prostate cancer cells by increasing m6A methylation of CDK4

Background

Methyltransferase-like (METTL) plays an important role in various biological processes, but its role in prostate cancer (PCa) is still unclear. This study aimed to explore the mechanism by which methyltransferase-like 14 (METTL14) inhibits the physiological activity of PCa cells by increasing the N6-methyladenosine (m6A) modification of cyclin-dependent kinase 4 (CDK4).

Methods

Clinical samples were collected for bioinformatics analysis. A PCa mouse model was constructed. Cell counting kit-8 (CCK-8), flow cytometry, colony formation assays, scratch assays, Transwell assays, real-time quantitative polymerase chain reaction (RT-qPCR), immunofluorescence and western blotting were used to detect the corresponding indicators.

Results

METTL14 was found to be beneficial to inhibit the proliferation, invasion, and migration of PCa cells. When the m6A RNA increased, the half-life of CDK4 mRNA decreased after oe-METTL14 (overexpression of METTL14). Overexpression of CDK4 reversed the effect of oe-METTL14. Coimmunoprecipitation experiments revealed there were interactions between CDK4 and forkhead box M1 (FOXM1). Transfection of si-CDK4 was similar to transfection of oe-METTL14. After transfection with oe-FOXM1, the invasion and migration ability of cells increased, and cell apoptosis decreased. After transfection with si-FOXM1 alone, autophagy related 7 (ATG7) expression was significantly downregulated, and autophagy levels were reduced. The overexpression of ATG7 reversed the effect of si-FOXM1. The tumor volume and weight of the oe-METTL14 group mice were significantly reduced, and tumor proliferation was decreased in comparison to untreated tumor-bearing mice.

Conclusions

METTL14 inhibits the invasion and migration of PCa cells and induces cell apoptosis by inhibiting CDK4 stability and FOXM1/ATG7-mediated autophagy.

Cross-talk between circRNAs and m6A modifications in solid tumors

Circular RNAs (circRNAs) possess unique biological properties and distribution characteristics that enable a variety of biological functions. N6-methyladenosine (m6A), a prevalent epigenetic modification in organisms, is regulated by factors including methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers). These factors play critical roles in various pathophysiological processes. There is growing evidence that m6A modifications are common within circRNAs, affecting their synthesis, translation, translocation, degradation, and stability. Additionally, circRNAs regulate biological processes that influence m6A modifications. This review explores the metabolism and functions of m6A modifications and circRNAs, their interactions, and their specific regulatory mechanisms in different tumors, offering insights into m6A-circRNA interaction in cancer.

N6-methyladenosine modification of hypoxia-inducible factor-1α regulates Helicobacter pylori-associated gastric cancer via the PI3K/AKT pathway

BACKGROUND

Helicobacter pylori (H. pylori) colonizes the human gastric mucosa and is implicated in the development of gastric cancer (GC). The tumor microenvironment is characterized by hypoxia, where hypoxia-inducible factor-1α (HIF-1α) plays a key role as a transcription factor, but the mechanisms underlying H. pylori-induced HIF-1α expression and carcinogenesis remain unclear.

AIM

To explore the underlying mechanism of H. pylori-induced HIF-1α expression in promoting the malignant biological behavior of gastric epithelial cells (GES-1).

METHODS

The study was conducted with human GES-1 cells in vitro. Relative protein levels of methyltransferase-like protein 14 (METTL14), HIF-1α, main proteins of the PI3K/AKT pathway, epithelial-mesenchymal transition (EMT) biomarkers, and invasion indicators were detected by Western blot. Relative mRNA levels of METTL14 and HIF-1α were detected by quantitative reverse transcription-polymerase chain reaction. mRNA stability was evaluated using actinomycin D, and the interaction between METTL14 and HIF-1α was confirmed by immunofluorescence staining. Cell proliferation and migration were evaluated by cell counting kit-8 assay and wound healing assay, respectively.

RESULTS

H. pylori promoted HIF-1α expression and activated the PI3K/AKT pathway. Notably, METTL14 was downregulated in H. pylori-infected gastric mucosal epithelial cells and positively regulated HIF-1α expression. Functional experiments showed that the overexpression of HIF-1α or knockdown of METTL14 enhanced the activity of the PI3K/AKT pathway, thereby driving a series of malignant transformation, such as EMT and cell proliferation, migration, and invasion. By contrast, the knockdown of HIF-1α or overexpression of METTL14 had an opposite effect.

CONCLUSION

H. pylori-induced underexpression of METTL14 promotes the translation of HIF-1α and accelerates tumor progression by activating the PI3K/AKT pathway. These results provide novel insights into the carcinogenesis of GC.

The regulatory mechanism of m6A modification in gastric cancer

To the best of our knowledge, N6-Methyladenosine (m6A) exerts a significant role in the occurrence and development of various tumors. Gastric cancer (GC), originating from the mucosal epithelium in the digestive tract, is the fifth most common cancer and the third most common cause of cancer death around the world. Therefore, it is urgent to explore the specific mechanism of tumorigenesis of GC. As we all know, m6A modification as the most common RNA modification, is involved in the modification of mRNA and ncRNA at the post-transcriptional level, which played a regulatory role in various biological processes. As identified by numerous studies, the m6A modification are able to influence the proliferation, apoptosis, migration, and invasion of GC. What's more, m6A modification are associated with EMT, drug resistance, and aerobic glycolysis in GC. m6A related-ncRNAs may be a valuable biomarker used by the prediction of GC diagnosis in the future. This review summarizes the role of m6A modification in the mechanism of gastric cancer, with the aim of identifying biological progress.

Except for Robust Outliers, Rapamycin Increases Lesion Burden in a Murine Model of Cerebral Cavernous Malformations

Cerebral cavernous malformation (CCM) is a hemorrhagic cerebrovascular disease where lesions develop in the setting of endothelial mutations of CCM genes, with many cases also harboring somatic PIK3CA gain of function (GOF) mutations. Rapamycin, an mTORC1 inhibitor, inhibited progression of murine CCM lesions driven by Ccm gene loss and Pik3ca GOF, but it remains unknown if rapamycin is beneficial in the absence of induction of Pik3ca GOF. We investigated the effect of rapamycin at three clinically relevant doses on lesion development in the Ccm3-/-PDGFb-icreERPositive murine model of familial CCM disease, without induction of Pik3ca GOF. Lesion burden, attrition, and acute and chronic hemorrhaging were compared between placebo and rapamycin-treated mice. Plasma miRNome was compared to identify potential biomarkers of rapamycin response. Outlier, exceptionally large CCM lesions (> 2 SD above the mean lesion burden) were exclusively observed in the placebo group. Rapamycin, across all dosages, may have prevented the emergence of large outlier lesions. Yet rapamycin also appeared to exacerbate mean lesion burden of surviving mice when outliers were excluded, increased attrition, and did not alter hemorrhage. miR-30c-2-3p, decreased in rapamycin-treated mouse plasma, has gene targets in PI3K/AKT and mTOR signaling. Progression of outlier lesions in a familial CCM model may have been halted by rapamycin treatment, at the potential expense of increased mean lesion burden and increased attrition. If confirmed, this can have implications for potential rapamycin treatment of familial CCM disease, where lesion development may not be driven by PIK3CA GOF. Further studies are necessary to determine specific pathways that mediate potential beneficial and detrimental effects of rapamycin treatment, and whether somatic PIK3CA mutations drive particularly aggressive lesions.

RNA demethylase FTO participates in malignant progression of gastric cancer by regulating SP1-AURKB-ATM pathway

Gastric cancer (GC) is the 5th most prevalent cancer and the 4th primary cancer-associated mortality globally. As the first identified m6A demethylase for removing RNA methylation modification, fat mass and obesity-associated protein (FTO) plays instrumental roles in cancer development. Therefore, we study the biological functions and oncogenic mechanisms of FTO in GC tumorigenesis and progression. In our study, FTO expression is obviously upregulated in GC tissues and cells. The upregulation of FTO is associated with advanced nerve invasion, tumor size, and LNM, as well as the poor prognosis in GC patients, and promoted GC cell viability, colony formation, migration and invasion. Mechanistically, FTO targeted specificity protein 1 and Aurora Kinase B, resulting in the phosphorylation of ataxia telangiectasia mutated and P38 and dephosphorylation of P53. In conclusion, the m6A demethylase FTO promotes GC tumorigenesis and progression by regulating the SP1-AURKB-ATM pathway, which may highlight the potential of FTO as a diagnostic biomarker for GC patients' therapy response and prognosis.

Recent advances in the reciprocal regulation of m6A modification with non-coding RNAs and its therapeutic application in acute myeloid leukemia

N6-methyladenosine (m6A) is one of the most common modifications of RNA in eukaryotic cells and is involved in mRNA metabolism, including stability, translation, maturation, splicing, and export. m6A also participates in the modification of multiple types of non-coding RNAs, such as microRNAs, long non-coding RNAs, and circular RNAs, thereby affecting their metabolism and functions. Increasing evidence has revealed that m6A regulators, such as writers, erasers, and readers, perform m6A-dependent modification of ncRNAs, thus affecting cancer progression. Moreover, ncRNAs modulate m6A regulators to affect cancer development and progression. In this review, we summarize recent advances in understanding m6A modification and ncRNAs and provide insights into the interaction between m6A modification and ncRNAs in cancer. We also discuss the potential clinical applications of the mechanisms underlying the interplay between m6A modifications and ncRNAs in acute myeloid leukemia (AML). Therefore, clarifying the mutual regulation between m6A modifications and ncRNAs is of great significance to identify novel therapeutic targets for AML and has great clinical application prospects.

Mechanisms and clinical landscape of N6-methyladenosine (m6A) RNA modification in gastrointestinal tract cancers

Epigenetics encompasses reversible and heritable chemical modifications of non-nuclear DNA sequences, including DNA and RNA methylation, histone modifications, non-coding RNA modifications, and chromatin rearrangements. In addition to well-studied DNA and histone methylation, RNA methylation has emerged as a hot topic in biological sciences over the past decade. N6-methyladenosine (m6A) is the most common and abundant modification in eukaryotic mRNA, affecting all RNA stages, including transcription, translation, and degradation. Advances in high-throughput sequencing technologies made it feasible to identify the chemical basis and biological functions of m6A RNA. Dysregulation of m6A levels and associated modifying proteins can both inhibit and promote cancer, highlighting the importance of the tumor microenvironment in diverse biological processes. Gastrointestinal tract cancers, including gastric, colorectal, and pancreatic cancers, are among the most common and deadly malignancies in humans. Growing evidence suggests a close association between m6A levels and the progression of gastrointestinal tumors. Global m6A modification levels are substantially modified in gastrointestinal tumor tissues and cell lines compared to healthy tissues and cells, possibly influencing various biological behaviors such as tumor cell proliferation, invasion, metastasis, and drug resistance. Exploring the diagnostic and therapeutic potential of m6A-related proteins is critical from a clinical standpoint. Developing more specific and effective m6A modulators offers new options for treating these tumors and deeper insights into gastrointestinal tract cancers.

MCM8 promotes gastric cancer progression through RPS15A and predicts poor prognosis

BACKGROUND

Gastric cancer (GC) is the fourth leading cause of cancer-related death worldwide. Minichromsome maintenance proteins family member 8 (MCM8) assists DNA repair and DNA replication. MCM8 exerts tumor promotor function in multiple digestive system tumors. MCM8 is also considered as a potential cancer therapeutic target.

METHODS

Bioinformatics methods were used to analyze MCM8 expression and clinicopathological significance. MCM8 expression was detected by immunohistochemistry (IHC) staining and qRT-PCR. MCM8 functions in GC cell were explored by Celigo cell counting, colony formation, wound-healing, transwell, and annexin V-APC staining assays. The target of MCM8 was determined by human gene expression profile microarray. Human phospho-kinase array kit evaluated changes in key proteins after ribosomal protein S15A (RPS15A) knockdown. MCM8 functions were reassessed in xenograft mouse model. IHC detected related proteins expression in mouse tumor sections.

RESULTS

MCM8 was significantly upregulated and predicted poor prognosis in GC. High expression of MCM8 was positively correlated with lymph node positive (p < 0.001), grade (p < 0.05), AJCC Stage (p < 0.001), pathologic T (p < 0.01), and pathologic N (p < 0.001). MCM8 knockdown inhibited proliferation, migration, and invasion while promoting apoptosis. RPS15A expression decreased significantly after MCM8 knockdown. It was also the only candidate target, which ranked among the top 10 downregulated differentially expressed genes (DEGs) in sh-MCM8 group. RPS15A was identified as the target of MCM8 in GC. MCM8/RPS15A promoted phosphorylation of P38α, LYN, and p70S6K. Moreover, MCM8 knockdown inhibited tumor growth, RPS15A expression, and phosphorylation of P38α, LYN, and p70S6K in vivo.

CONCLUSIONS

MCM8 is an oncogene and predicts poor prognosis in GC. MCM8/RPS15A facilitates GC progression.

KIAA1429 promotes gastric cancer progression by destabilizing RASD1 mRNA in an m6A-YTHDF2-dependent manner

BACKGROUND

KIAA1429, a regulatory subunit of the N6-methyladenosine (m6A) methyltransferase complex, has been implicated in the progression of various cancers. However, the role of KIAA1429 in gastric cancer (GC) and its underlying mechanisms remain elusive. This study aimed to investigate the role of KIAA1429 in GC and to elucidate the underlying mechanisms.

METHODS

The expression patterns and clinical relevance of KIAA1429 in GC were assessed using quantitative real-time PCR (qRT-PCR), Western blotting, immunohistochemistry (IHC), and bioinformatic analysis. In vitro and in vivo loss- and gain-of-function assays, m6A dot blot assays, methylated RNA immunoprecipitation sequencing (MeRIP-seq), RNA-seq, MeRIP-qPCR, dual luciferase reporter assays, RNA stability assays, RNA immunoprecipitation (RIP) assays, and RNA pull-down assays were performed to investigate the biological functions and underlying molecular mechanisms of KIAA1429 in GC.

RESULTS

Both the mRNA and protein expression of KIAA1429 were greater in GC tissues than in normal gastric tissues. High KIAA1429 expression correlated positively with poor prognosis in GC patients. KIAA1429 not only promoted GC cell proliferation, colony formation, G2/M cell cycle transition, migration, and invasion in vitro but also enhanced GC tumor growth and metastasis in vivo. Mechanistically, KIAA1429 increased the m6A level of RASD1 mRNA and enhanced its stability in an m6A-YTHDF2-dependent manner, thereby upregulating its expression. RASD1 knockdown partially rescued the KIAA1429 knockdown-induced impairment of pro‑oncogenic ability in GC cells. The expression levels of KIAA1429 and RASD1 were negatively correlated in GC tissues.

CONCLUSIONS

KIAA1429 plays a pro‑oncogenic role in GC by downregulating RASD1 expression through destabilizing RASD1 mRNA in an m6A-YTHDF2-dependent manner. KIAA1429 may serve as a prognostic biomarker and therapeutic target for GC.

METTL14 inhibits the malignant processes of gastric cancer cells by promoting N6-methyladenosine (m6A) methylation of TAF10

N6-methyladenosine (m6A) methylation mediates cancer development by regulating cell proliferation and metastasis. This study aimed to identify whether methyltransferase 14 (METTL14) affects gastric cancer (GC) cellular functions and its underlying mechanism. METTL14 and TATA-box binding protein associated factor 10 (TAF10) levels were examined using quantitative real-time PCR, immunohistochemical assay, and Western blot. Biological functions were assessed using cell counting kit-8, colony formation, and transwell assays. The interaction between METTL14 and TAF10 was analyzed using RNA immunoprecipitation, methylated RNA immunoprecipitation, and luciferase reporter assay. A xenograft tumor mouse model was established to assess the role of METTL14 in vivo. The results suggested that METTL14 was low expressed and TAF10 was highly expressed in GC tissues and cells. METTL14 overexpression inhibited GC cell viability, colony, migration, and invasion. TAF10 was predicted and confirmed to be negatively related to METTL14. METTL14 promoted m6A methylation of TAF10 and inhibited TAF10 stability. Moreover, TAF10 counteracted the cellular behaviors regulated by METTL14. Overexpression of METTL14 inhibited tumor growth and histopathology. In conclusion, METTL14 inhibits GC progression by attenuating GC cell proliferation, migration, and invasion. Mechanistically, METTL14 promoted m6A methylation of TAF10, suppressed the stability of TAF10, and thus downregulated the TAF10 levels, These results provide a new insight into GC therapy.

CircUGGT2 downregulation by METTL14-dependent m6A modification suppresses gastric cancer progression and cisplatin resistance through interaction with miR-186-3p/MAP3K9 axis

Chemoresistance is a major therapeutic challenge in advanced gastric cancer (GC). N6-methyladenosine (m6A) RNA modification has been shown to play fundamental roles in cancer progression. However, the underlying mechanisms by which m6A modification of circRNAs contributes to GC and chemoresistance remain unknown. We found that hsa_circ_0030632 (circUGGT2) was a predominant m6A target of METTL14, and METTL14 knockdown (KD) reduced circUGGT2 m6A levels but increased its mRNA levels. The expression of circUGGT2 was markedly increased in cisplatin (DDP)-resistant GC cells. CircUGGT2 KD impaired cell growth, metastasis and DDP-resistance in vitro and in vivo, but circUGGT2 overexpression prompted these effects. Furthermore, circUGGT2 was validated to sponge miR-186-3p and upregulate MAP3K9 and could abolish METTL14-caused miR-186-3p upregulation and MAP3K9 downregulation in GC cells. circUGGT2 negatively correlated with miR-186-3p expression and harbored a poor prognosis in patients with GC. Our findings unveil that METTL14-dependent m6A modification of circUGGT2 inhibits GC progression and DDP resistance by regulating miR-186-3p/MAP3K9 axis.

Ramifications of m6A Modification on ncRNAs in Cancer

N6-methyladenosine (m6A) is an RNA modification wherein the N6-position of adenosine is methylated. It is one of the most prevalent internal modifications of RNA and regulates various aspects of RNA metabolism. M6A is deposited by m6A methyltransferases, removed by m6A demethylases, and recognized by reader proteins, which modulate splicing, export, translation, and stability of the modified mRNA. Recent evidence suggests that various classes of non- coding RNAs (ncRNAs), including microRNAs (miRNAs), circular RNAs (circRNAs), and long con-coding RNAs (lncRNAs), are also targeted by this modification. Depending on the ncRNA species, m6A may affect the processing, stability, or localization of these molecules. The m6A- modified ncRNAs are implicated in a number of diseases, including cancer. In this review, the author summarizes the role of m6A modification in the regulation and functions of ncRNAs in tumor development. Moreover, the potential applications in cancer prognosis and therapeutics are discussed.

Identification of differentially expressed mRNAs as novel predictive biomarkers for gastric cancer diagnosis and prognosis

BACKGROUND

Gastric cancer (GC) has a high mortality rate worldwide. Despite significant progress in GC diagnosis and treatment, the prognosis for affected patients still remains unfavorable.

AIM

To identify important candidate genes related to the development of GC and identify potential pathogenic mechanisms through comprehensive bioinformatics analysis.

METHODS

The Gene Expression Omnibus database was used to obtain the GSE183136 dataset, which includes a total of 135 GC samples. The limma package in R software was employed to identify differentially expressed genes (DEGs). Thereafter, enrichment analyses of Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were performed for the gene modules using the clusterProfile package in R software. The protein-protein interaction (PPI) networks of target genes were constructed using STRING and visualized by Cytoscape software. The common hub genes that emerged in the cohort of DEGs that was retrieved from the GEPIA database were then screened using a Venn Diagram. The expression levels of these overlapping genes in stomach adenocarcinoma samples and non-tumor samples and their association with prognosis in GC patients were also obtained from the GEPIA database and Kaplan-Meier curves. Moreover, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting were performed to determine the mRNA and protein levels of glutamic-pyruvic transaminase (GPT) in GC and normal immortalized cell lines. In addition, cell viability, cell cycle distribution, migration and invasion were evaluated by cell counting kit-8, flow cytometry and transwell assays. Furthermore, we also conducted a retrospective analysis on 70 GC patients diagnosed and surgically treated in Wenzhou Central Hospital, Dingli Clinical College of Wenzhou Medical University, The Second Affiliated Hospital of Shanghai University between January 2017 to December 2020. The tumor and adjacent normal samples were collected from the patients to determine the potential association between the expression level of GPT and the clinical as well as pathological features of GC patients.

RESULTS

We selected 19214 genes from the GSE183136 dataset, among which there were 250 downregulated genes and 401 upregulated genes in the tumor samples of stage III-IV in comparison to those in tumor samples of stage I-II with a P-value < 0.05. In addition, GO and KEGG results revealed that the various upregulated DEGs were mainly enriched in plasma membrane and neuroactive ligand-receptor interaction, whereas the downregulated DEGs were primarily enriched in cytosol and pancreatic secretion, vascular smooth muscle contraction and biosynthesis of the different cofactors. Furthermore, PPI networks were constructed based on the various upregulated and downregulated genes, and there were a total 15 upregulated and 10 downregulated hub genes. After a comprehensive analysis, several hub genes, including runt-related transcription factor 2 (RUNX2), salmonella pathogenicity island 1 (SPI1), lysyl oxidase (LOX), fibrillin 1 (FBN1) and GPT, displayed prognostic values. Interestingly, it was observed that GPT was downregulated in GC cells and its upregulation could suppress the malignant phenotypes of GC cells. Furthermore, the expression level of GPT was found to be associated with age, lymph node metastasis, pathological staging and distant metastasis (P < 0.05).

CONCLUSION

RUNX2, SPI1, LOX, FBN1 and GPT were identified key hub genes in GC by bioinformatics analysis. GPT was significantly associated with the prognosis of GC, and its upregulation can effectively inhibit the proliferative, migrative and invasive capabilities of GC cells.

METTL5 promotes gastric cancer progression via sphingomyelin metabolism

BACKGROUND

The treatment of gastric cancer (GC) has caused an enormous social burden worldwide. Accumulating studies have reported that N6-methyladenosine (m6A) is closely related to tumor progression. METTL5 is a m6A methyltransferase that plays a pivotal role in maintaining the metabolic stability of cells. However, its aberrant regulation in GC has not been fully elucidated.

AIM

To excavate the role of METTL5 in the development of GC.

METHODS

METTL5 expression and clinicopathological characteristics were analyzed via The Cancer Genome Atlas dataset and further verified via immunohistochemistry, western blotting and real-time quantitative polymerase chain reaction in tissue microarrays and clinical samples. The tumor-promoting effect of METTL5 on HGC-27 and AGS cells was explored in vitro by Cell Counting Kit-8 assays, colony formation assays, scratch healing assays, transwell assays and flow cytometry. The tumor-promoting role of METTL5 in vivo was evaluated in a xenograft tumor model. The EpiQuik m6A RNA Methylation Quantification Kit was used for m6A quantification. Next, liquid chromatography-mass spectrometry was used to evaluate the association between METTL5 and sphingomyelin metabolism, which was confirmed by Enzyme-linked immunosorbent assay and rescue tests. In addition, we investigated whether METTL5 affects the sensitivity of GC cells to cisplatin via colony formation and transwell experiments.

RESULTS

Our research revealed substantial upregulation of METTL5, which suggested a poor prognosis of GC patients. Increased METTL5 expression indicated distant lymph node metastasis, advanced cancer stage and pathological grade. An increased level of METTL5 correlated with a high degree of m6A methylation. METTL5 markedly promotes the proliferation, migration, and invasion of GC cells in vitro. METTL5 also promotes the growth of GC in animal models. METTL5 knockdown resulted in significant changes in sphingomyelin metabolism, which implies that METTL5 may impact the development of GC via sphingomyelin metabolism. In addition, high METTL5 expression led to cisplatin resistance.

CONCLUSION

METTL5 was found to be an oncogenic driver of GC and may be a new target for therapy since it facilitates GC carcinogenesis through sphingomyelin metabolism and cisplatin resistance.

ALKBH5-mediated m6A modification of circFOXP1 promotes gastric cancer progression by regulating SOX4 expression and sponging miR-338-3p

Circular RNAs (circRNAs) have recently been suggested as potential functional modulators of cellular physiology processes in gastric cancer (GC). In this study, we demonstrated that circFOXP1 was more highly expressed in GC tissues. High circFOXP1 expression was positively associated with tumor size, lymph node metastasis, TNM stage, and poor prognosis in patients with GC. Cox multivariate analysis revealed that higher circFOXP1 expression was an independent risk factor for disease-free survival (DFS) and overall survival (OS) in GC patients. Functional studies showed that increased circFOXP1 expression promoted cell proliferation, cell invasion, and cell cycle progression in GC in vitro. In vivo, the knockdown of circFOXP1 inhibited tumor growth. Mechanistically, we observed ALKBH5-mediated m6A modification of circFOXP1 and circFOXP1 promoted GC progression by regulating SOX4 expression and sponging miR-338-3p in GC cells. Thus, our findings highlight that circFOXP1 could serve as a novel diagnostic and prognostic biomarker and potential therapeutic target for GC.

METTL3 modification of circStk4 affects mouse glomerular messangial cell autophagy, proliferation and apotosis by regulating miR-133a-3p/C1 axis

OBJECTIVE

The study aimed to explore the impact of N6-methyladenosine (m6A) modification in circStk4 on glomerular mesangial cells (GMCs) autophagy, proliferation and apoptosis.

METHODS

The interactions between circStk4 and miR-133a-3p, miR-133a-3p and C1 were demonstrated through luciferase reporter assays. The circStk4 localization was analyzed using fluorescence in situ hybridization and nuclear/cytosol fractionation assays. Colorimetric assays, MeRIP-qPCR, and western blot (WB) were employed to confirm the m6A modification of circStk4 and identify the key methylation enzyme. RT-qPCR was conducted to determine the impact of METTL3 on the circStk4 RNA expression. Additionally, CCK-8, flow cytometry, transmission electron microscopy, immunofluorescence, WB and RT-qPCR were employed to investigate the effects of METTL3 or circStk4 on the proliferation, autophagy and apoptosis of GMCs. Enzyme-linked immunosorbent assay was utilized to assess the inflammatory factors.

RESULTS

m6A modifications were found in circStk4 and METTL3 was a key methylating enzyme. Furthermore, it was observed that circStk4 competitively bound miR-133a-3p and increased C1 levels. Silencing circStk4 resulted in decreased GMCs proliferation, increased autophagy and apoptosis, and reduced inflammation levels. Additionally, METTL3 played a role in inhibiting GMCs proliferation and promoting autophagy and apoptosis by regulating the circStk4 expression. On verifying the interplay between autophagy, proliferation and apoptosis, and found that the inhibition of autophagy led to an increase in cell proliferation and a decrease in apoptosis.

CONCLUSION

m6A modification of circStk4 mediated by METTL3 influenced circStk4 expression and impacted autophagy, proliferation and apoptosis in GMCs via the miR-133a-3p/C1 axis. This discovery introduces a novel therapeutic approach for CGN treatment.

Lnc-PLCB1 is stabilized by METTL14 induced m6A modification and inhibits Helicobacter pylori mediated gastric cancer by destabilizing DDX21

Helicobacter pylori (H. pylori) infection is considered to be an important factor in gastric cancer (GC). Long noncoding RNA (lncRNA) and m6A modification are involved in the occurrence and development of GC, but the role of lncRNA m6A modification in the development of GC mediated by H. pylori is still unclear. Here, we found that H. pylori infection downregulated the expression of lnc-PLCB1 through METTL14-mediated m6A modification and IRF2-mediated transcriptional regulation. Overexpression of lnc-PLCB1 inhibited the proliferation and migration of GC cells, while downregulation of lnc-PLCB1 promoted the proliferation and migration ability of GC cells. In addition, clinical analysis showed that lnc-PLCB1 is lower in GC tissues than in normal tissues. Further study found that lnc-PLCB1 reduced the protein stability of its binding protein DEAD-box helicase 21 (DDX21) and then downregulated the expression of CCND1 and Slug, thereby playing tumour suppressing role in the occurrence and development of GC. In conclusion, the METTL14/lnc-PLCB1/DDX21 axis plays an important role in H. pylori-mediated GC, and lnc-PLCB1 can be used as a new target for GC treatment.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

Crosstalk between m6A modification and autophagy in cancer

Autophagy is a cellular self-degradation process that plays a crucial role in maintaining metabolic functions in cells and organisms. Dysfunctional autophagy has been linked to various diseases, including cancer. In cancer, dysregulated autophagy is closely associated with the development of cancer and drug resistance, and it can have both oncogenic and oncostatic effects. Research evidence supports the connection between m6A modification and human diseases, particularly cancer. Abnormalities in m6A modification are involved in the initiation and progression of cancer by regulating the expression of oncogenes and oncostatic genes. There is an interaction between m6A modification and autophagy, both of which play significant roles in cancer. However, the molecular mechanisms underlying this relationship are still unclear. m6A modification can either directly inhibit autophagy or promote its initiation, but the complex relationship between m6A modification, autophagy, and cancer remains poorly understood. Therefore, this paper aims to review the dual role of m6A and autophagy in cancer, explore the impact of m6A modification on autophagy regulation, and discuss the crucial role of the m6A modification-autophagy axis in cancer progression and treatment resistance.

Emerging roles of circular RNAs in regulating the hallmarks of thyroid cancer

Thyroid cancer is a prevalent endocrine malignancy with increasing incidence in recent years. Although most thyroid cancers grow slowly, they can become refractory, leading to a high mortality rate once they exhibit recurrence, metastasis, resistance to radioiodine therapy, or a lack of differentiation. However, the mechanisms underlying these malignant characteristics remain unclear. Circular RNAs, a type of closed-loop non-coding RNAs, play multiple roles in cancer. Several studies have demonstrated that circular RNAs significantly influence the development of thyroid cancers. In this review, we summarize the circular RNAs identified in thyroid cancers over the past decade according to the hallmarks of cancer. We found that eight of the 14 hallmarks of thyroid cancers are regulated by circular RNAs, whereas the other six have not been reported to be correlated with circular RNAs. This review is expected to help us better understand the roles of circular RNAs in thyroid cancers and accelerate research on the mechanisms and cure strategies for thyroid cancers.

Emerging function of main RNA methylation modifications in the immune microenvironment of digestive system tumors

Digestive system tumors have been reported in more than 25% of all cancer cases worldwide, bringing a huge burden on the healthcare system. RNA methylation modification-an important post-transcriptional modification-has become an active research area in gene regulation. It is a dynamic and reversible process involving several enzymes, such as methyltransferases, demethylases, and methylation reader proteins. This review provides insights into the role of three major methylation modifications, namely m6A, m5C, and m1A, in the development of digestive system tumors, specifically in the development of tumor immune microenvironment (TIME) of these malignancies. Abnormal methylation modification affects immunosuppression and antitumor immune response by regulating the recruitment of immune cells and the release of immune factors. Understanding the mechanisms by which RNA methylation regulates digestive system tumors will be helpful in exploring new therapeutic targets.

Gastric Cancer in the Era of Epigenetics

Gastric cancer (GC) remains a significant contributor to cancer-related mortality. Novel high-throughput techniques have enlightened the epigenetic mechanisms governing gene-expression regulation. Epigenetic characteristics contribute to molecular taxonomy and give rise to cancer-specific epigenetic patterns. Helicobacter pylori (Hp) infection has an impact on aberrant DNA methylation either through its pathogenic CagA protein or by inducing chronic inflammation. The hypomethylation of specific repetitive elements generates an epigenetic field effect early in tumorigenesis. Epstein-Barr virus (EBV) infection triggers DNA methylation by dysregulating DNA methyltransferases (DNMT) enzyme activity, while persistent Hp-EBV co-infection leads to aggressive tumor behavior. Distinct histone modifications are also responsible for oncogene upregulation and tumor-suppressor gene silencing in gastric carcinomas. While histone methylation and acetylation processes have been extensively studied, other less prevalent alterations contribute to the development and migration of gastric cancer via a complex network of interactions. Enzymes, such as Nicotinamide N-methyltransferase (NNMT), which is involved in tumor's metabolic reprogramming, interact with methyltransferases and modify gene expression. Non-coding RNA molecules, including long non-coding RNAs, circular RNAs, and miRNAs serve as epigenetic regulators contributing to GC development, metastasis, poor outcomes and therapy resistance. Serum RNA molecules hold the potential to serve as non-invasive biomarkers for diagnostic, prognostic or therapeutic applications. Gastric fluids represent a valuable source to identify potential biomarkers with diagnostic use in terms of liquid biopsy. Ongoing clinical trials are currently evaluating the efficacy of next-generation epigenetic drugs, displaying promising outcomes. Various approaches including multiple miRNA inhibitors or targeted nanoparticles carrying epigenetic drugs are being designed to enhance existing treatment efficacy and overcome treatment resistance.

Non-coding RNA-Mediated N6-Methyladenosine (m6A) deposition: A pivotal regulator of cancer, impacting key signaling pathways in carcinogenesis and therapy response

The emergence of RNA modifications has recently been considered as critical post-transcriptional regulations which governed gene expression. N6-methyladenosine (m6A) modification is the most abundant type of RNA modification which is mediated by three distinct classes of proteins called m6A writers, readers, and erasers. Accumulating evidence has been made in understanding the role of m6A modification of non-coding RNAs (ncRNAs) in cancer. Importantly, aberrant expression of ncRNAs and m6A regulators has been elucidated in various cancers. As the key role of ncRNAs in regulation of cancer hallmarks is well accepted now, it could be accepted that m6A modification of ncRNAs could affect cancer progression. The present review intended to discuss the latest knowledge and importance of m6A epigenetic regulation of ncRNAs including mircoRNAs, long non-coding RNAs, and circular RNAs, and their interaction in the context of cancer. Moreover, the current insight into the underlying mechanisms of therapy resistance and also immune response and escape mediated by m6A regulators and ncRNAs are discussed.

Emerging roles of circular RNAs in tumorigenesis, progression, and treatment of gastric cancer

With an estimated one million new cases reported annually, gastric cancer (GC) ranks as the fifth most diagnosed malignancy worldwide. The early detection of GC remains a major challenge, and the prognosis worsens either when patients develop resistance to chemotherapy or radiotherapy or when the cancer metastasizes. The precise pathogenesis underlying GC is not well understood, which further complicates its treatment. Circular RNAs (circRNAs), a recently discovered class of noncoding RNAs that originate from parental genes through "back-splicing", have been shown to play a key role in various biological processes in both eukaryotes and prokaryotes. CircRNAs have been linked to cardiovascular diseases, diabetes, hypertension, Alzheimer's disease, and the occurrence and progression of tumors. Prior studies have established that circRNAs play a crucial role in GC, impacting tumorigenesis, diagnosis, progression, and therapy resistance. This review aims to summarize how circRNAs contribute to GC tumorigenesis and progression, examine their roles in the development of drug resistance, discuss their potential as biotechnological drugs, and summarize their response to therapeutic drugs and microorganism in GC.

Significance of N6-methyladenosine RNA methylation regulators in diagnosis and subtype classification of primary Sjögren's syndrome

The importance of N6-methyladenine (m6A) in mRNA metabolism, physiology, pathology and other life processes is well recognized. However, the exact role of m6A regulators in primary Sjögren's syndrome (PSS) remains unclear. In this study, we used bioinformatics and machine learning random forest approach to screen eight key m6A regulators from the Gene Expression Omnibus GSE7451, GSE40611 and GSE84844 datasets. An accurate nomogram model for predicting PSS risk was established based on these regulators. And using consensus clustering, patients diagnosed with PSS were classified into two different m6A patterns. We found that patients in group B had higher m6A scores compared to those in group A: furthermore, both groups were closely related to immunity and possibly to other diseases. These results emphasise the important role of m6A regulators in the pathogenesis of PSS. Our study of m6A patterns may inform future immunotherapy strategies for PSS.

miR-30c affects the pathogenesis of ulcerative colitis by regulating target gene VIP

MicroRNAs play a crucial role in regulating the epithelial barrier and immune response, which are implicated in the pathogenesis of ulcerative colitis (UC). This study aimed to investigate the role and molecular mechanism of miR-30c in the pathogenesis of UC using a dextran sulfate sodium salt (DSS)-induced colitis model, which is similar to ulcerative colitis. Wild-type (WT) and miR-30c knockout (KO) mice were assigned to either control or DSS-treated groups to evaluate the influence of aberrant miR-30c expression on UC pathogenesis. The disease activity index, inflammatory factors, and the extent of pathological and histological damage in colon tissues were analyzed. The effect of miR-30c on vasoactive intestinal peptide (VIP) gene expression was validated through luciferase reporter assay, qRT-PCR, Western blotting, and immunohistochemistry. The results showed that miR-30c KO mice with DSS-induced colitis model showed more severe phenotypes: significantly higher disease activity indices, significant body weight loss, reduced length of the colon of mice, increased number of aberrant crypt structures, reduced mucus secretion, and significant differences in inflammatory factors. These findings suggested that the absence of miR-30c might promote DSS-induced colitis, and the targe-regulatory effect of miR-30c on VIP might play an important role in the development of colitis.

METTL14 enhances the m6A modification level of lncRNA MSTRG.292666.16 to promote the progression of non-small cell lung cancer

BACKGROUND

m6A modification has close connection with the occurrence, development, and prognosis of tumors. This study aimed to explore the roles of m6A modification and its related mechanisms in non-small cell lung cancer (NSCLC).

METHODS

NSCLC tissues and their corresponding para-cancerous tissues were collected to determine the m6A levels of total RNA/lncRNAs and the expression of m6A modification-related genes/lncRNAs. Then, A549 cells were transfected with si-METTL14 or oe-METTL14, and the cell transfection efficiency was assessed. Subsequently, the viability, apoptosis, cell colony formation, migration and invasion of the different cells were determined. Finally, the nude mouse tumorigenicity experiments were performed to observe the effects of METTL14 in vivo.

RESULTS

Compared to the para-NSCLC tissues, the m6A level and METTL14 expression were both significantly increased in the NSCLC tissues (P < 0.05). Based on the expression of METTL14 in the different cell lines, A549 cells were chosen for further experiments. Then, the A549 cells with METTL14 knockdown and overexpression were successfully established, as well as it was found that METTL14 knockdown could inhibit the viability, colony formation, migration, and invasion of A549 cells, while facilitate their apoptosis. In vivo experiments also showed that METTL14 knockdown could inhibit tumor formation and growth. Additionally, the m6A level of MSTRG.292666.16 was higher in the NSCLC tissues; and after METTL14 knockdown, the expression and m6A level of MSTRG.292666.16 were both significantly reduced in A549 cells, and vice versa.

CONCLUSION

METTL14 may promote the progression of NSCLC through up-regulating MSTRG.292666.16 and enhance its m6A modification level.

IGF2BP2-m6A-circMMP9 axis recruits ETS1 to promote TRIM59 transcription in laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is a common malignancy of the head and neck. Recently, circular RNA (circRNA) has been studied extensively in multisystem diseases. However, there are few research on biological functions and molecular mechanisms of circRNAs in LSCC. CircRNA array was used to detect the differentially expressed circRNAs. Kaplan-Meier and cox regression analysis were used to identify survival based on circMMP9. The qRT-PCR, RNase R treatment, sanger sequencing and in situ hybridization were used to verify circMMP9 expression, characteristics and localization in LSCC tissues and cells. Functionally, colony formation, MTS, transwell and in vivo assays were proceeded to detect the biological function of circMMP9 in LSCC progression. The RNA-seq was conducted to identify the molecular targets of circMMP9. Mechanically, MeRIP, RNA Immunoprecipitation (RIP), RNA pulldown, Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were carried on to verify the regulatory mechanism of circMMP9. CircMMP9 was discovered upregulated in LSCC tissues and cells, and high level of circMMP9 was associated with poor prognosis, low degree of pathological grading, high TNM stage and lymph node metastasis of LSCC. CircMMP9 knockdown prevented LSCC progression both in vitro and in vivo, whereas, circMMP9 overexpression had the opposite effect. CircMMP9 was stabilized by IGF2BP2 in m6A-dependent manner. TRIM59 was identified as downstream target of circMMP9. CircMMP9 recruited ETS1 to stimulate TRIM59 transcription. Moreover, TRIM59 accelerated LSCC progression via activating the PI3K/AKT signal pathway. Our findings offered a unique regulatory mechanism for circMMP9 in LSCC, as well as a novel proof that circMMP9 may be utilize as a diagnostic marker and therapeutic target for LSCC patients.

METTL14/miR-29c-3p axis drives aerobic glycolysis to promote triple-negative breast cancer progression though TRIM9-mediated PKM2 ubiquitination

The energy metabolic rearrangement of triple-negative breast cancer (TNBC) from oxidative phosphorylation to aerobic glycolysis is a significant biological feature and can promote the malignant progression. However, there is little knowledge about the functional mechanisms of methyltransferase-like protein 14 (METTL14) mediated contributes to TNBC malignant progression. Our study found that METTL14 expression was significantly upregulated in TNBC tissues and cell lines. Silencing METTL14 significantly inhibited TNBC cell growth and invasion in vitro, as well as suppressed tumour growth. Mechanically, METTL14 was first found to activate miR-29c-3p through m6A and regulate tripartite motif containing 9 (TRIM9) to promote ubiquitination of pyruvate kinase isoform M2 (PKM2) and lead to its transition from tetramer to dimer, resulting in glucose metabolic reprogramming from oxidative phosphorylation to aerobic glycolysis to promote the progress of TNBC. Taken together, these findings reveal important roles of METTL14 in TNBC tumorigenesis and energy metabolism, which might represent a novel potential therapeutic target for TNBC.

N6-methylation in the development, diagnosis, and treatment of gastric cancer

Gastric cancer (GC) ranks third among cancers in terms of mortality rate worldwide. A clear understanding of the mechanisms underlying the genesis and progression of GC will contribute to clinical decision making. N6-methyladenosine (m6A) is the most abundant among diverse mRNA modification types and regulates multiple facets of RNA metabolism. In recent years, emerging studies have shown that m6A modifications are involved in gastric carcinoma tumorigenesis and progression and can potentially be valuable new prospects for diagnosis and prognosis. This article reviews the recent progress regarding m6A in GC.

Exploring the interplay between methylation patterns and non-coding RNAs in non-small cell lung cancer: Implications for pathogenesis and therapeutic targets

Lung cancer is a global public health issue, with non-small cell lung cancer (NSCLC) accounting for 80-85 % of cases. With over two million new diagnoses annually, understanding the complex evolution of this disease is crucial. The development of lung cancer involves a complex interplay of genetic, epigenetic, and environmental factors, leading the key oncogenes and tumor suppressor genes to disorder, and activating the cancer related signaling pathway. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNA (lncRNAs), and circular RNA (circRNAs) are unique RNA transcripts with diverse biological functions. These ncRNAs are generated through genome transcription and play essential roles in cellular processes. Epigenetic modifications such as DNA methylation, N6-methyladenosine (m6A) modification, and histone methylation have gained significant attention in NSCLC research. The complexity of the interactions among these methylation modifications and ncRNAs contribute to the precise regulation of NSCLC development. This review comprehensively summarizes the associations between ncRNAs and different methylation modifications and discusses their effects on NSCLC. By elucidating these relationships, we aim to advance our understanding of NSCLC pathogenesis and identify potential therapeutic targets for this devastating disease.