RNA N6-methyladenosine: a new player in autophagy-mediated anti-cancer drug resistance

METTL14 decreases FTH1 mRNA stability via m6A methylation to promote sorafenib-induced ferroptosis of cervical cancer

Cervical cancer (CC) is a prevalent malignancy among women worldwide. This study was designed to investigate the role of METTL14 in sorafenib-induced ferroptosis in CC. METTL14 expression and m6A methylation were determined in CC tissues, followed by analyzes correlating these factors with clinical features. Subsequently, METTL14 was knocked down in CC cell lines, and the effects on cell proliferation, mitochondrial morphology and ferroptosis were assessed using CCK-8, microscopy, and markers associated with ferroptosis, respectively. The regulatory relationship between METTL14 and FTH1 was verified using qRT-PCR and luciferase reporter assays. The functional significance of this interaction was further investigated both in vitro and in vivo by co-transfecting cells with overexpression vectors or shRNAs targeting METTL14 and FTH1 after sorafenib treatment. METTL14 expression and m6A methylation were significantly reduced in CC tissues, and lower METTL14 expression levels were associated with a poorer CC patients' prognosis. Notably, METTL14 expression increased during sorafenib-induced ferroptosis, and METTL14 knockdown attenuated the ferroptotic response induced by sorafenib in CC cells. FTH1 was identified as a direct target of METTL14, with METTL14 overexpression leading to increased m6A methylation of FTH1 mRNA, resulting in reduced stability and expression of FTH1 in CC. Furthermore, FTH1 overexpression or treatment with LY294002 partially counteracted the promotion of sorafenib-induced ferroptosis by METTL14. In vivo xenograft experiments demonstrated that inhibiting METTL14 reduced the anticancer effects of sorafenib, whereas suppression of FTH1 significantly enhanced sorafenib-induced ferroptosis and increased its anticancer efficacy. METTL14 reduces FTH1 mRNA stability through m6A methylation, thereby enhancing sorafenib-induced ferroptosis, which contributes to suppressing CC progression via the PI3K/Akt signaling pathway.

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.

METTL3/16-mediated m6A modification of ZNNT1 promotes hepatocellular carcinoma progression by activating ZNNT1/osteopontin/S100A9 positive feedback loop-mediated crosstalk between macrophages and tumour cells

Macrophages are the major components of tumour microenvironment, which play critical roles in tumour development. N6-methyladenosine (m6A) also contributes to tumour progression. However, the potential roles of m6A in modulating macrophages in hepatocellular carcinoma (HCC) are poorly understood. Here, we identified ZNNT1 as an HCC-related m6A modification target, which was upregulated and associated with poor prognosis of HCC. METTL3 and METTL16-mediated m6A modification contributed to ZNNT1 upregulation through stabilizing ZNNT1 transcript. ZNNT1 exerted oncogenic roles in HCC. Furthermore, ZNNT1 recruited and induced M2 polarization of macrophages via up-regulating osteopontin (OPN) expression and secretion. M2 Macrophages-recruited by ZNNT1-overexpressed HCC cells secreted S100A9, which further upregulated ZNNT1 expression in HCC cells via AGER/NF-κB signaling. Thus, this study demonstrates that m6A modification activated the ZNNT1/OPN/S100A9 positive feedback loop, which promoted macrophages recruitment and M2 polarization, and enhanced malignant features of HCC cells. m6A modification-triggered ZNNT1/OPN/S100A9 feedback loop represents potential therapeutic target for HCC.

N6-Methyladenosine-Modified ATP8B1-AS1 Exerts Oncogenic Roles in Hepatocellular Carcinoma via Epigenetically Activating MYC

Purpose

N6-methyladenosine (m6A) modification has shown critical roles in regulating mRNA fate. Non-coding RNAs also have important roles in various diseases, including hepatocellular carcinoma (HCC). However, the potential influences of m6A modification on non-coding RNAs are still unclear. In this study, we identified a novel m6A-modified ATP8B1-AS1 and aimed to investigate the effects of m6A on the expression and role of ATP8B1-AS1 in HCC.

Methods

qPCR was performed to measure the expression of related genes. The correlation between gene expression and prognosis was analyzed using public database. m6A modification level was measured using MeRIP and single-base elongation- and ligation-based qPCR amplification method. The roles of ATP8B1-AS1 in HCC were investigated using in vitro and in vivo functional assays. The mechanisms underlying the roles of ATP8B1-AS1 were investigated by ChIRP and ChIP assays.

Results

ATP8B1-AS1 is highly expressed in HCC tissues and cell lines. High expression of ATP8B1-AS1 is correlated with poor overall survival of HCC patients. ATP8B1-AS1 is m6A modified and the 792 site of ATP8B1-AS1 is identified as an m6A modification site. m6A modification increases the stability of ATP8B1-AS1 transcript. m6A modification level of ATP8B1-AS1 is increased in HCC tissues and cell lines, and correlated with poor overall survival of HCC patients. ATP8B1-AS1 promotes HCC cell proliferation, migration, and invasion, which were abolished by the mutation of m6A-modified 792 site. Mechanistic investigation revealed that m6A-modified ATP8B1-AS1 interacts with and recruits m6A reader YTHDC1 and histone demethylase KDM3B to MYC promoter region, leading to the reduction of H3K9me2 level at MYC promoter region and activation of MYC transcription. Functional rescue assays showed that depletion of MYC largely abolished the oncogenic roles of ATP8B1-AS1.

Conclusion

m6A modification level of ATP8B1-AS1 is increased and correlated with poor prognosis in HCC. m6A-modified ATP8B1-AS1 exerts oncogenic roles in HCC via epigenetically activating MYC expression.

N6 -methyladenosine-modified FAM111A-DT promotes hepatocellular carcinoma growth via epigenetically activating FAM111A

As an epitranscriptomic modulation manner, N6 -methyladenosine (m6 A) modification plays important roles in various diseases, including hepatocellular carcinoma (HCC). m6 A modification affects the fate of RNAs. The potential contributions of m6 A to the functions of RNA still need further investigation. In this study, we identified long noncoding RNA FAM111A-DT as an m6 A-modified RNA and confirmed three m6 A sites on FAM111A-DT. The m6 A modification level of FAM111A-DT was increased in HCC tissues and cell lines, and increased m6 A level was correlated with poor survival of HCC patients. m6 A modification increased the stability of FAM111A-DT transcript, whose expression level showed similar clinical relevance to that of the m6 A level of FAM111A-DT. Functional assays found that only m6 A-modified FAM111A-DT promoted HCC cellular proliferation, DNA replication, and HCC tumor growth. Mutation of m6 A sites on FAM111A-DT abolished the roles of FAM111A-DT. Mechanistic investigations found that m6 A-modified FAM111A-DT bound to FAM111A promoter and also interacted with m6 A reader YTHDC1, which further bound and recruited histone demethylase KDM3B to FAM111A promoter, leading to the reduction of the repressive histone mark H3K9me2 and transcriptional activation of FAM111A. The expression of FAM111A was positively correlated with the m6 A level of FAM111A-DT, and the expression of methyltransferase complex, YTHDC1, and KDM3B in HCC tissues. Depletion of FAM111A largely attenuated the roles of m6 A-modified FAM111A-DT in HCC. In summary, the m6 A-modified FAM111A-DT/YTHDC1/KDM3B/FAM111A regulatory axis promoted HCC growth and represented a candidate therapeutic target for HCC.

Association between autophagy and acute pancreatitis

Autophagy pathway involves maintaining intracellular homeostasis by regulating the degradation of cytoplasmic components. Disfunction of autophagic process has been confirmed to be critical mechanism in many diseases, including cancer, inflammation, infection, degeneration and metabolic disorders. Recent studies have shown that autophagy is one of the early events in acute pancreatitis. Impaired autophagy promotes the abnormal activation of zymogen granules and results in apoptosis and necrosis of exocrine pancreas. Furthermore, multiple signal paths involve progression of acute pancreatitis by regulating autophagy pathway. This article provides a comprehensive review of the recent advances in epigenetic regulation of autophagy and the role of autophagy in acute pancreatitis.

Unraveling the Complex Interactions between the Fat Mass and Obesity-Associated (FTO) Gene, Lifestyle, and Cancer

Carcinogenesis is a complicated process and originates from genetic, epigenetic, and environmental factors. Recent studies have reported a potential critical role for the fat mass and obesity-associated (FTO) gene in carcinogenesis through different signaling pathways such as mRNA N6-methyladenosine (m6A) demethylation. The most common internal modification in mammalian mRNA is the m6A RNA methylation that has significant biological functioning through regulation of cancer-related cellular processes. Some environmental factors, like physical activity and dietary intake, may influence signaling pathways engaged in carcinogenesis, through regulating FTO gene expression. In addition, people with FTO gene polymorphisms may be differently influenced by cancer risk factors, for example, FTO risk allele carriers may need a higher intake of nutrients to prevent cancer than others. In order to obtain a deeper viewpoint of the FTO, lifestyle, and cancer-related pathway interactions, this review aims to discuss upstream and downstream pathways associated with the FTO gene and cancer. The present study discusses the possible mechanisms of interaction of the FTO gene with various cancers and provides a comprehensive picture of the lifestyle factors affecting the FTO gene as well as the possible downstream pathways that lead to the effect of the FTO gene on cancer.

Research progress of ginseng in the treatment of gastrointestinal cancers

Cancer has become one of the major causes of human death. Several anticancer drugs are available; howeve their use and efficacy are limited by the toxic side effects and drug resistance caused by their continuous application. Many natural products have antitumor effects with low toxicity and fewer adverse effects. Moreover, they play an important role in enhancing the cytotoxicity of chemotherapeutic agents, reducing toxic side effects, and reversing chemoresistance. Consequently, natural drugs are being applied as potential therapeutic options in the field of antitumor treatment. As natural medicinal plants, some components of ginseng have been shown to have excellent efficacy and a good safety profile for cancer treatment. The pharmacological activities and possible mechanisms of action of ginseng have been identified. Its broad range of pharmacological activities includes antitumor, antibacterial, anti-inflammatory, antioxidant, anti-stress, anti-fibrotic, central nervous system modulating, cardioprotective, and immune-enhancing effects. Numerous studies have also shown that throuth multiple pathways, ginseng and its active ingredients exert antitumor effects on gastrointestinal (GI) tract tumors, such as esophageal, gastric, colorectal, liver, and pancreatic cancers. Herein, we introduced the main components of ginseng, including ginsenosides, polysaccharides, and sterols, etc., and reviewed the mechanism of action and research progress of ginseng in the treatment of various GI tumors. Futhermore, the pathways of action of the main components of ginseng are discussed in depth to promote the clinical development and application of ginseng in the field of anti-GI tumors.

Mutual regulation between N6-methyladenosine (m6A) modification and circular RNAs in cancer: impacts on therapeutic resistance

The resistance of tumor cells to therapy severely impairs the efficacy of treatment, leading to recurrence and metastasis of various cancers. Clarifying the underlying mechanisms of therapeutic resistance may provide new strategies for overcoming cancer resistance. N6-methyladenosine (m6A) is the most prevalent RNA modification in eukaryotes, and is involved in the regulation of RNA splicing, translation, transport, degradation, stability and processing, thus affecting several physiological processes and cancer progression. As a novel type of multifunctional non-coding RNAs (ncRNAs), circular RNAs (circRNAs) have been demonstrated to play vital roles in anticancer therapy. Currently, accumulating studies have revealed the mutual regulation of m6A modification and circRNAs, and their interaction can further influence the sensitivity of cancer treatment. In this review, we mainly summarized the recent advances of m6A modification and circRNAs in the modulation of cancer therapeutic resistance, as well as their interplay and potential mechanisms, providing promising insights and future directions in reversal of therapeutic resistance in cancer.

METTL16 promotes hepatocellular carcinoma progression through downregulating RAB11B-AS1 in an m6A-dependent manner

BACKGROUND

The molecular mechanisms driving hepatocellular carcinoma (HCC) remain largely unclear. As one of the major epitranscriptomic modifications, N6-methyladenosine (m6A) plays key roles in HCC. The aim of this study was to investigate the expression, roles, and mechanisms of action of the RNA methyltransferase methyltransferase-like protein 16 (METTL16) in HCC.

METHODS

The expression of METTL16 and RAB11B-AS1 was determined by RT-qPCR. The regulation of RAB11B-AS1 by METTL16 was investigated by RNA immunoprecipitation (RIP), methylated RIP (MeRIP), and RNA stability assays. In vitro and in vivo gain- and loss-of-function assays were performed to investigate the roles of METTL16 and RAB11B-AS1.

RESULTS

METTL16 was upregulated in HCC, and its increased expression was correlated with poor prognosis of HCC patients. METTL16 promoted HCC cellular proliferation, migration, and invasion, repressed HCC cellular apoptosis, and promoted HCC tumoral growth in vivo. METTL16 directly bound long noncoding RNA (lncRNA) RAB11B-AS1, induced m6A modification of RAB11B-AS1, and decreased the stability of RAB11B-AS1 transcript, leading to the downregulation of RAB11B-AS1. Conversely to METTL16, RAB11B-AS1 is downregulated in HCC, and its decreased expression was correlated with poor prognosis of patients with HCC. Furthermore, the expression of RAB11B-AS1 was negatively correlated with METTL16 in HCC tissues. RAB11B-AS1 repressed HCC cellular proliferation, migration, and invasion, promoted HCC cellular apoptosis, and inhibited HCC tumoral growth in vivo. Functional rescue assays revealed that overexpression of RAB11B-AS1 reversed the oncogenic roles of METTL16 in HCC.

CONCLUSIONS

This study identified the METTL16/RAB11B-AS1 regulatory axis in HCC, which represented novel targets for HCC prognosis and treatment.

5-Azacytidine Inhibits the Activation of Senescence Program and Promotes Cytotoxic Autophagy during Trdmt1-Mediated Oxidative Stress Response in Insulinoma β-TC-6 Cells

5-Azacytidine (5-azaC), a methyltransferase inhibitor and anticancer drug, can promote several cellular stress responses such as apoptosis, autophagy, and senescence. The action of 5-azaC is complex and can be modulated by dose, time of treatment, and co-administration with oxidants. Insulinoma is a rare pancreatic neuroendocrine tumor with limited chemotherapeutic options. In the present study, two cellular models of insulinoma were considered, namely NIT-1 and β-TC-6 mouse cells, to evaluate the effects of 5-azaC post-treatment during hydrogen peroxide-induced oxidative stress. 5-azaC attenuated the development of oxidant-induced senescent phenotype in both cell lines. No pro-apoptotic action of 5-azaC was observed in cells treated with the oxidant. On the contrary, 5-azaC stimulated an autophagic response, as demonstrated by the increase in phosphorylated eIF2α and elevated pools of autophagic marker LC3B in oxidant-treated β-TC-6 cells. Notably, autophagy resulted in increased necrotic cell death in β-TC-6 cells with higher levels of nitric oxide compared to less affected NIT-1 cells. In addition, 5-azaC increased levels of RNA methyltransferase Trdmt1, but lowered 5-mC and m⁶A levels, suggesting Trdmt1 inhibition. We postulate that the 5-azaC anticancer action may be potentiated during oxidative stress conditions that can be used to sensitize cancer cells, at least insulinoma cells, with limited drug responsiveness.

Potential applications of N6 -methyladenosine modification in the prognosis and treatment of cancers via modulating apoptosis, autophagy, and ferroptosis

N⁶ -methyladenosine (m⁶ A) is one of the most abundant modifications determining the fate of RNA. Currently, m⁶ A modification is tightly connected with tumorigenesis and presents novel promise in clinical applications. Regulated cell death (RCD) is a programmed mechanism that plays a complicated role in malignant transition. Regarding the main forms of RCD, aberrant levels of m⁶ A modification have been detected during the progression of apoptosis, autophagy, ferroptosis, necroptosis, and pyroptosis in several diseases. However, few reviews have elucidated the correlation between m⁶ A-modified RCD and carcinogenesis. In this review, we summarize the regulators of m⁶ A methylation and their functions in carcinogenesis through an overview of m⁶ A-modified RCD. Additionally, we assume the potential role of m⁶ A modification regulators as novel biomarkers for chemotherapies and precision medicine. Furthermore, we review the controversies and conflicts in m⁶ A explorations and predict future orientations of m⁶ A-modified RCD for clinical applications. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.

The Prognostic Value and Immune Landscapes of a m6A/m5C/m1A-Related LncRNAs Signature in Head and Neck Squamous Cell Carcinoma

Background: N6-methyladenosine (m6A), 5-methylcytosine (m5C) and N1-methyladenosine (m1A) are the main RNA methylation modifications involved in the progression of cancer. However, it is still unclear whether m6A/m5C/m1A-related long non-coding RNAs (lncRNAs) affect the prognosis of head and neck squamous cell carcinoma (HNSCC). Methods: We summarized 52 m6A/m5C/m1A-related genes, downloaded 44 normal samples and 501 HNSCC tumor samples with RNA-seq data and clinical information from The Cancer Genome Atlas (TCGA) database, and then searched for m6A/m5C/m1A-related genes co-expressed lncRNAs. We adopt the least absolute shrinkage and selection operator (LASSO) Cox regression to obtain m6A/m5C/m1A-related lncRNAs to construct a prognostic signature of HNSCC. Results: This prognostic signature is based on six m6A/m5C/m1A-related lncRNAs (AL035587.1, AC009121.3, AF131215.5, FMR1-IT1, AC106820.5, PTOV1-AS2). It was found that the high-risk subgroup has worse overall survival (OS) than the low-risk subgroup. Moreover, the results showed that most immune checkpoint genes were significantly different between the two risk groups (p < 0.05). Immunity microenvironment analysis showed that the contents of NK cell resting, macrophages M2, and neutrophils in samples of low-risk group were significantly lower than those of high-risk group (p < 0.05), while the contents of B cells navie, plasma cells, and T cells regulatory (Tregs) were on the contrary (p < 0.05). In addition, patients with high tumor mutational burden (TMB) had the worse overall survival than those with low tumor mutational burden. Conclusion: Our study elucidated how m6A/m5C/m1A-related lncRNAs are related to the prognosis, immune microenvironment, and TMB of HNSCC. In the future, these m6A/m5C/m1A-related lncRNAs may become a new choice for immunotherapy of HNSCC.