N6-methyladenosine demethylase ALKBH5 suppresses colorectal cancer progression potentially by decreasing PHF20 mRNA methylation

Interplay of m6A RNA methylation and gut microbiota in modulating gut injury

The gut microbiota undergoes continuous variations among individuals and across their lifespan, shaped by diverse factors encompassing diet, age, lifestyle choices, medication intake, and disease states. These microbial inhabitants play a pivotal role in orchestrating physiological metabolic pathways through the production of metabolites like bile acids, choline, short-chain fatty acids, and neurotransmitters, thereby establishing a dynamic "gut-organ axis" with the host. The intricate interplay between the gut microbiota and the host is indispensable for gut health, and RNA N6-methyladenosine modification, a pivotal epigenetic mark on RNA, emerges as a key player in this process. M6A modification, the most prevalent internal modification of eukaryotic RNA, has garnered significant attention in the realm of RNA epigenetics. Recent findings underscore its potential to influence gut microbiota diversity and intestinal barrier function by modulating host gene expression patterns. Conversely, the gut microbiota, through its impact on the epigenetic landscape of host cells, may indirectly regulate the recruitment and activity of RNA m6A-modifying enzymes. This review endeavors to delve into the biological functions of m6A modification and its consequences on intestinal injury and disease pathogenesis, elucidating the partial possible mechanisms by which the gut microbiota and its metabolites maintain host intestinal health and homeostasis. Furthermore, it also explores the intricate crosstalk between them in intestinal injury, offering a novel perspective that deepens our understanding of the mechanisms underlying intestinal diseases.

m6A methylation modification of RNA plays a significant role in the occurrence and development of colorectal cancer

Colorectal cancer is the third most common malignant tumor worldwide and ranks second in terms of mortality. N6-methyladenosine (m6A) modification is the most prevalent internal covalent modification in eukaryotic mRNA and is involved in various stages of RNA processing, including splicing, degradation, and export, playing a crucial role in the onset and progression of many diseases. The m6A modification is co-regulated by methyltransferases, demethylases, and methyl-binding proteins, and it has become a hot topic in cancer research. Based on a systematic review of existing studies on the role of m6A modification in colorectal cancer, this article further expands the research horizon in this field and effectively overcomes the limitations of existing reviews that only focus on discussing a single or a class of methylation regulators.

RNA demethylase ALKBH5 regulates cell cycle progression in DNA damage response

RNA N6-methyladenosine (m6A) modification plays a crucial role in the DNA damage response, while the detailed mechanisms remain to be explored. In this study, we report the involvement of the m6A demethylase ALKBH5 in X-ray-induced DNA damage response. Depletion of ALKBH5 reduces X-ray-induced DNA damage, induces G2/M phase arrest and reduces cell apoptosis. RNA sequencing and m6A sequencing analysis reveal that ALKBH5 removes m6A modifications from its target mRNAs and suppresses their expression. A subset of mRNAs encoding cyclin dependent kinase inhibitors, such as CDKN1A and CDKN2B, show increased stability and expression upon ALKBH5 knockdown. Subsequently, the upregulation of CDKN1A and CDKN2B contributes to G2/M phase arrest to facilitate DNA repair. Our findings unveil the epigenetic regulation of cell cycle checkpoint by ALKBH5 in X-ray-induced DNA damage, offering potential targets for DNA damage-based therapy for cancers.

Role and mechanisms of m6A demethylases in digestive system tumors

Digestive system tumors are common malignancies in humans, often accompanied by high mortality and poor prognosis. Therefore, intensive research on the pathogenesis of digestive system tumors is imperative. N6-methyladenosine (m6A) is the most common RNA modification in eukaryotes and exerts regulatory effects on RNA expression and metabolism, including splicing, translation, stability, decay, and transport. m6A demethylases belong to the AlkB family of dioxygenases that can catalyze m6A demethylation. Accumulating evidence in recent years has shown that abnormal m6A levels caused by m6A demethylases play crucial roles in different aspects of human cancer development. In this review, we comprehensively summarize the recent findings on the functions and underlying molecular mechanisms of m6A demethylases in cell proliferation, apoptosis, migration, invasion, metastasis, angiogenesis, resistance to chemo- and radiotherapy, and the tumor immune microenvironment (TIME) of digestive system tumors. Furthermore, we discuss the therapeutic potential of targeting these m6A demethylases for treatment.

Role of the m6A demethylase ALKBH5 in gastrointestinal tract cancer (Review)

N6‑methyladenosine (m6A) is one of the most universal, abundant and conserved types of internal post‑transcriptional modifications in eukaryotic RNA, and is involved in nuclear RNA export, RNA splicing, mRNA stability, gene expression, microRNA biogenesis and long non‑coding RNA metabolism. AlkB homologue 5 (ALKBH5) acts as a m6A demethylase to regulate a wide variety of biological processes closely associated with tumour progression, tumour metastasis, tumour immunity and tumour drug resistance. ALKBH5 serves a crucial role in human digestive system tumours, mainly through post‑transcriptional regulation of m6A modification. The present review discusses progress in the study of the m6A demethylase ALKBH5 in gastrointestinal tract cancer, summarizes the potential molecular mechanisms of ALKBH5 dysregulation in gastrointestinal tract cancer, and discusses the significance of ALKBH5‑targeted therapy, which may provide novel ideas for future clinical prognosis prediction, biomarker identification and precise treatment.

M6A Demethylase ALKBH5 in Human Diseases: From Structure to Mechanisms

N6-methyladenosine (m6A) is the most abundant, dynamically reversible, and evolutionarily conserved internal chemical modification in eukaryotic RNA. It is emerging as critical for regulating gene expression at the post-transcriptional level by affecting RNA metabolism through, for example, pre-mRNA processing, mRNA decay, and translation. ALKBH5 has recently been identified as an endogenous m6A demethylase implicated in a multitude of biological processes. This review provides an overview of the structural and functional characteristics of ALKBH5 and the involvement of ALKBH5 in diverse human diseases, including metabolic, immune, reproductive, and nervous system disorders, as well as the development of inhibitors. In summation, this review highlights the current understanding of the structure, functions, and detailed mechanisms of ALKBH5 in various physiological and pathological processes and provides valuable insights for clinical applications and foundational research within related fields.

ALKBH5 suppresses gastric cancer tumorigenesis and metastasis by inhibiting the translation of uncapped WRAP53 RNA isoforms in an m6A-dependent manner

The N6-methyladenosine (m6A) modification serves as an essential epigenetic regulator in eukaryotic cells, playing a significant role in tumorigenesis and cancer progression. However, the detailed biological functions and underlying mechanisms of m6A regulation in gastric cancer (GC) are poorly understood. Our research revealed that the m6A demethylase ALKBH5 was markedly downregulated in GC tissues, which was associated with poor patient prognosis. Functional studies demonstrated that suppressing ALKBH5 expression enhanced GC cell proliferation, migration, and invasion. Mechanistically, ALKBH5 removed m6A modifications from the 5' uncapped and polyadenylated transcripts (UPTs) of WRAP53. This demethylation decreased WRAP53 stability and translation efficiency. The lower level of WRAP53 disrupts the interaction between USP6 and RALBP1 protein, promoting RALBP1 degradation and thereby suppressing the PI3K/Akt/mTOR signaling cascade, ultimately attenuating the progression of GC. These findings highlight the pivotal role of ALKBH5-mediated m6A demethylation in inhibiting GC progression and the potential role of ALKBH5 as a promising biomarker and therapeutic target for GC intervention.

ALKBH5 controlled autophagy of peripheral blood mononuclear cells by regulating NRG1 mRNA stability in ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease which is characterized by pathological osteogenesis. N6-methyladenosine (m6A) RNA modification is pivotal in immunity and inflammation. In this study, the peripheral blood mononuclear cells (PBMCs) were isolated from healthy or AS patients blood samples in Fuyang People's Hospital, which was utilized to clarify the role of m6A modification in AS pathogenesis. The results showed that the autophagy levels showed a decreasing trend; meanwhile, the m6A demethylase ALKBH5 expression was downregulation in AS-PBMCs. The RNA-seq analysis identified 201 significantly altered genes including NRG1, FOS, CAMKK2, NLRC4, and DAPK1; and NRG1 mRNA expression levels showed significant improvement in AS. After ALKBH5 knockdown, the autophagy levels significantly decreased through increasing NRG1 m6A modification and enhancing its mRNA stability, while ALKBH5 overexpression promoted autophagy by reduceing NRG1 mRNA stability. Additionally, the results found that the "reader" IGF2BP3 substantially enhanced NRG1 expression and mRNA stability in AS patients PBMCs. Silencing ALKBH5 increased IGF2BP3 binding to the m6A-enriched NRG1 transcript, and enhancing NRG1 mRNA stability and protein expression. However, ALKBH5 modification site mutation may increase IGF2BP3 binding to NRG1 mRNA. These finding suggested that ALKBH5 downregulation inhibited AS-PBMCs autophagy leves through regulating post-transcriptional m6A modification to upregulate NRG1 protein expression, which provided novel and effective approaches for AS clinical therapy.

Epigenetic modification mediated by PHF20/METTL14/HOXA13 signaling axis modulates osteogenic differentiation of mesenchymal stem cells

This study investigates the mechanism of PHF20 in osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). BMSCs from Balb/c mouse were cultured and identified through osteogenesis, adipogenesis, and flow cytometry. After osteogenic induction, the levels of OPN and OCN in BMSCs were detected by RT-qPCR. Alizarin red staining and alkaline phosphatase (ALP) staining were used to evaluate the osteogenic differentiation ability of BMSCs. PHF20, METTL14, and HOXA13 expressions were detected by RT-qPCR and Western blot. After quantitative analysis of m6A level, RNA immunoprecipitation (RIP) was performed to measure the enrichment of IGF2BP3 or m6A on HOXA13 mRNA. HOXA13 mRNA stability was assessed after actinomycin D treatment. PHF20, METT14, and HOXA13 expressions gradually increased during osteogenic differentiation of BMSCs. Suppression of PHF20 expression repressed the osteogenic differentiation of BMSCs, mainly resulted in a decrease in OPN and OCN levels, reduced mineralization, and weakened ALP activity. Mechanistically, PHF20 elevated METTL14 expression by enhancing the enrichment of H3K4me3 on its promoter, and METTL14 strengthened HOXA13 m6A methylation to maintain HOXA13 mRNA stability through IGF2BP3. In conclusion, PHF20 elevates METTL14 expression by enhancing H3K4me3 enrichment on its promoter and enhances HOXA13 mRNA stability via IGF2BP3-mediated m6A modification, thus facilitating HOXA13 expression and eventually inducing osteogenic differentiation of BMSCs.

ALKBH5 promotes malignant proliferation of renal clear cell carcinoma by activating the MAPK pathway through binding to HNRNPDL

It is well established that ALKBH5 plays a crucial role in the malignant progression of various types of tumors. However, its role in clear cell renal cell carcinoma (ccRCC) and the underlying regulatory mechanisms remain unclear. In this study, we employed a range of techniques, including protein blotting, real-time quantitative PCR, silver staining, mass spectrometry, co-immunoprecipitation (Co-IP), GST-pull down, and immunofluorescence, to investigate the functions of ALKBH5 in ccRCC and elucidate the specific mechanisms involved. Our results demonstrated that ALKBH5 expression was significantly upregulated in ccRCC. In vitro experiments revealed that ALKBH5 promoted tumor proliferation, invasion, migration, and stemness. In vivo, ALKBH5 was shown to enhance tumor growth and lung metastasis. Mechanistically, our studies suggest that ALKBH5 accelerates the malignant progression of ccRCC by binding to heterogeneous nuclear ribonucleoprotein D-like (HNRNPDL), facilitating the nuclear translocation of MEK, ERK, and p38, and activating downstream targets such as c-Myc and PCNA.

Exploring the various functions of PHD finger protein 20: beyond the unknown

Over the last decade, the functions of PHD finger protein 20 (PHF20) in several signaling processes have been studied, including those of protein kinase B (PKB)-mediated phosphorylation, p53 regulation, muscle differentiation, and histone modification including histone H3 lysine 4 (H3K4) methylation. One PHF20 human mutation lacks the first nonspecific lethal complex of the component that binds to H3K4me2 to facilitate cancer cell survival. In carcinoma cells, PHF20 expression is regulated by PKB; PHF20 becomes phosphorylated when DNA is damaged, thus inhibiting the p53 activity that maintains cancer cell survival. Given this regulatory effect, PHF20 is usually expressed not only in gliomas but also in breast cancers, colorectal cancers, and other diseases associated with skeletal muscle osteoblastosis and osteoporosis. Thus, PHF20 dysregulation and its downstream effects enhance the abnormalities associated with cancers or other diseases and encourage disease progression. Moreover, PHF20 serves as a nuclear factor kappa-light-chain enhancer of B cell activation, thus increasing pro-inflammatory cytokine production, associated with crosstalk involving the mouse double minute 2 homolog that in turn reduces the normal p53 levels not only in cancers but also in damaged or otherwise injured normal tissues. Despite the findings of various studies, the roles of PHF20 in terms of prognosis, diagnosis, and targeting of disease therapies remain unclear and should be further explored.

Unraveling molecular and clinical aspects of ALKBH5 as dual role in colorectal cancer

OBJECTIVES

This study investigates the dual role of ALKBH5, an eraser enzyme, in colorectal cancer (CRC), focusing on how N6-methyladenosine (m6A) mutations influence CRC development and progression.

METHODS

We reviewed various studies that highlighted the role of ALKBH5 in colorectal cancer (CRC). This includes the impact of ALKBH5 on tumor cell behavior including immune system interactions, invasion, and proliferation in CRC. We also looked into how ALKBH5 acts as a tumor suppressor under different conditions analyzed clinical data to assess the impact of ALKBH5 expression on outcomes in colorectal cancer patients.

KEY FINDINGS

In CRC, ALKBH5 plays a dual role. In certain situations, it inhibits the progression of the tumor, but in other circumstances, it promotes tumor growth and immunosuppression. The interaction with RABA5 plays a role in the development of CRC. Having elevated levels of ALKBH5 has been associated with unfavorable patient outcomes, such as reduced survival rates and more advanced cancer stages. Various factors, including tumor differentiation, TNM stages, and carcinoembryonic antigen (CEA) levels, be linked to ALKBH5 expression.

CONCLUSIONS

ALKBH5 plays a complicated and situation-specific role in colorectal cancer (CRC). Targeting ALKBH5 could result in novel therapy options that balance its tumor-promoting and tumor-fighting properties in CRC. Further research into m6A alterations and ALKBH5 could enhance CRC treatment approaches and patient outcomes.

m6A-modified circXPO1 accelerates colorectal cancer progression via interaction with FMRP to promote WWC2 mRNA decay

BACKGROUND

Recent evidence has demonstrated the vital roles of circular RNAs (circRNAs) in the progression of colorectal cancer (CRC); however, their functions and mechanisms in CRC need to be further explored. This study aimed to uncover the biological function of circXPO1 in CRC progression.

METHODS

CircXPO1 was identified by Sanger sequencing, RNase R, and actinomycin D treatment assays. Colony formation, scratch, transwell assays, and mouse xenograft models were adopted to evaluate CRC cell growth and metastasis in vitro and in vivo. Subcellular expression of circXPO1 was detected by FISH and nuclear-cytoplasmic separation assays. Molecular mechanisms were investigated by MeRIP, RIP, and RNA pull-down assays. Target molecular expression was detected by RT-qPCR, Western blotting and immunohistochemical staining.

RESULTS

circXPO1 was up-regulated in CRC tissues and cells, which indicated a poor prognosis of CRC patients. circXPO1 deficiency delayed the growth, EMT, and metastasis of CRC cells. Mechanistical experiments indicated that down-regulation of ALKBH5 enhanced IGF2BP2-mediated m6A modification of circXPO1 to increase circXPO1 expression. Furthermore, circXPO1 interacted with FMRP to reduce the mRNA stability of WWC2, which consequently resulted in Hippo-YAP pathway activation. Rescue experiments suggested that WWC2 overexpression abrogated circXPO1-mediated malignant capacities of CRC cells. The in vivo growth and liver metastasis of CRC cells were restrained by circXPO1 depletion or WWC2 overexpression.

CONCLUSIONS

m6A-modified circXPO1 by ALKBH5/IGF2BP2 axis destabilized WWC2 via interaction with FMRP to activate Hippo-YAP pathway, thereby facilitating CRC growth and metastasis. Targeting circXPO1 might be a potential therapeutic strategy for CRC.

Modulation of host N6-methyladenosine modification by gut microbiota in colorectal cancer

As a research hotspot in the field of molecular biology, N6-methyladenosine (m6A) modification has made progress in the treatment of colorectal cancer (CRC), leukemia and other cancers. Numerous studies have demonstrated that the tumour microenvironment (TME) regulates the level of m6A modification in the host and activates a series of complex epigenetic signalling pathways through interactions with CRC cells, thus affecting the progression and prognosis of CRC. However, with the diversity in the composition of TME factors, this action is reciprocal and complex. Encouragingly, some studies have experimentally revealed that the intestinal flora can alter CRC cell proliferation by directly acting on m6A and thereby altering CRC cell proliferation. This review summarizes the data, supporting the idea that the intestinal flora can influence host m6A levels through pathways such as methyl donor metabolism and thus affect the progression of CRC. We also review the role of m6A modification in the diagnosis, treatment, and prognostic assessment of CRC and discuss the current status, limitations, and potential clinical value of m6A modification in this field. We propose that additional in-depth research on m6A alterations in CRC patients and their TME-related targeted therapeutic issues will lead to better therapeutic outcomes for CRC patients.

ALKBH5 promotes hepatocellular carcinoma cell proliferation, migration and invasion by regulating TTI1 expression

The objective of this research was to investigate the potential mechanisms of AlkB homolog 5, RNA demethylase (ALKBH5) in hepatocellular carcinoma (HCC). We used The Cancer Genome Atlas (TCGA), Kruskal-Wallis method and Kaplan-Meier (KM) survival analysis to study the expression of ALKBH5 and its correlation with clinical factors in HCC. In vitro experiments verified the expression of ALKBH5 and its effect on HCC cell phenotype. We screened differentially expressed genes (DEGs) from HCC patients associated with ALKBH5. Through this screening we identified the downstream gene TTI1 which is associated with ALKBH5 and investigated its function using Gene Expression Profiling Interaction Analysis (GEPIA) along with univariate Cox proportional hazards regression analysis. Finally, we analyzed the functions of ALKBH5 and TTI1 in HCC cells. Across numerous pan-cancer types, we observed significant overexpression of ALKBH5. In vitro experiments confirmed ALKBH5 as an oncogene in HCC, with its knockdown leading to suppressed cell proliferation, migration, and invasion. Bioinformatics analyses also demonstrated a significant positive correlation between ALKBH5 and TTI1. TTI1, highly expressed in cells, showed promising prognostic ability for patients. Further experiments confirmed that suppressing TTI1 impeded cell growth and movement, with this effect partially offset by increased ALKBH5 expression. Conversely, promoting these cellular processes was observed with TTI1 overexpression, but was dampened by decreased ALKBH5 expression. In conclusion, our findings suggest that ALKBH5 may influence proliferation, migration and invasion of HCC by modulating TTI1 expression, providing a new direction for treating HCC.

Complicated role of ALKBH5 in gastrointestinal cancer: an updated review

Gastrointestinal cancer is the most common malignancy in humans, often accompanied by poor prognosis. N6-methyladenosine (m6A) modification is widely present in eukaryotic cells as the most abundant RNA modification. It plays a crucial role in RNA splicing and processing, nuclear export, translation, and stability. Human AlkB homolog 5 (ALKBH5) is a type of RNA demethylase exhibiting abnormal expression in various gastrointestinal cancers.It is closely related to the tumorigenesis, proliferation, migration, and other biological functions of gastrointestinal cancer. However, recent studies indicated that the role and mechanism of ALKBH5 in gastrointestinal cancer are complicated and even controversial. Thus, this review summarizes recent advances in elucidating the role of ALKBH5 as a tumor suppressor or promoter in gastrointestinal cancer. It examines the biological functions of ALKBH5 and its potential as a therapeutic target, providing new perspectives and insights for gastrointestinal cancer research.

N6-methyladenosine-dependent signaling in colorectal cancer: Functions and clinical potential

Colorectal cancer (CRC) ranks as the third most prevalent malignancy worldwide. Despite the gradual expansion of therapeutic options for CRC, its clinical management remains a formidable challenge. And, because of the current dearth of technical means for early CRC screening, most patients are diagnosed at an advanced stage. Therefore, it is imperative to develop novel diagnostic and therapeutic tools for this disease. N6-methyladenosine (m6A), the predominant RNA modification in eukaryotes, can be recognized by m6A-specific methylated reading proteins to modulate gene expression. Studies have revealed that CRC disrupts m6A homeostasis through various mechanisms, thereby sustaining aberrant signal transduction and promoting its own progression. Consequently, m6A-based diagnostic and therapeutic strategies have garnered widespread attention. Although utilizing m6A as a biomarker and drug target has demonstrated promising feasibility, existing observations primarily stem from preclinical models; henceforth necessitating further investigation and resolution of numerous outstanding issues.

Demethylases in tumors and the tumor microenvironment: Key modifiers of N6-methyladenosine methylation

RNA methylation modifications are widespread in eukaryotes and prokaryotes, with N6-methyladenosine (m6A) the most common among them. Demethylases, including Fat mass and obesity associated gene (FTO) and AlkB homolog 5 (ALKBH5), are important in maintaining the balance between RNA methylation and demethylation. Recent studies have clearly shown that demethylases affect the biological functions of tumors by regulating their m6A levels. However, their effects are complicated, and even opposite results have appeared in different articles. Here, we summarize the complex regulatory networks of demethylases, including the most important and common pathways, to clarify the role of demethylases in tumors. In addition, we describe the relationships between demethylases and the tumor microenvironment, and introduce their regulatory mechanisms. Finally, we discuss evaluation of demethylases for tumor diagnosis and prognosis, as well as the clinical application of demethylase inhibitors, providing a strong basis for their large-scale clinical application in the future.

RNA methylation: A potential therapeutic target in autoimmune disease

Autoimmune diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD) are caused by the body's immune response to autoantigens. The pathogenesis of autoimmune diseases is unclear. Numerous studies have demonstrated that RNA methylation plays a key role in disease progression, which is essential for post-transcriptional regulation and has gradually become a broad regulatory mechanism that controls gene expression in various physiological processes, including RNA nuclear output, translation, splicing, and noncoding RNA processing. Here, we outline the writers, erasers, and readers of RNA methylation, including N6-methyladenosine (m6A), 2'-O-methylation (Nm), 2'-O-dimethyladenosine (m6Am), N1-methyladenosine (m1A), 5-methylcytidine (m5C) and N7-methylguanosine (m7G). As the role of RNA methylation modifications in the immune system and diseases is explained, the potential treatment value of these modifications has also been demonstrated. This review reports the relationship between RNA methylation and autoimmune diseases, highlighting the need for future research into the therapeutic potential of RNA modifications.

A multi-omics analysis-based model to predict the prognosis of low-grade gliomas

Lower-grade gliomas (LGGs) exhibit highly variable clinical behaviors, while classic histology characteristics cannot accurately reflect the authentic biological behaviors, clinical outcomes, and prognosis of LGGs. In this study, we carried out analyses of whole exome sequencing, RNA sequencing and DNA methylation in primary vs. recurrent LGG samples, and also combined the multi-omics data to construct a prognostic prediction model. TCGA-LGG dataset was searched for LGG samples. 523 samples were used for whole exome sequencing analysis, 532 for transcriptional analysis, and 529 for DNA methylation analysis. LASSO regression was used to screen genes with significant association with LGG survival from the frequently mutated genes, differentially expressed genes, and differentially methylated genes, whereby a prediction model for prognosis of LGG was further constructed and validated. The most frequently mutated diver genes in LGGs were IDH1 (77%), TP53 (48%), ATRX (37%), etc. Top significantly up-regulated genes were C6orf15, DAO, MEOX2, etc., and top significantly down-regulated genes were DMBX1, GPR50, HMX2, etc. 2077 genes were more and 299 were less methylated in recurrent vs. primary LGG samples. Thirty-nine genes from the above analysis were included to establish a prediction model of survival, which showed that the high-score group had a very significantly shorter survival than the low-score group in both training and testing sets. ROC analysis showed that AUC was 0.817 for the training set and 0.819 for the testing set. This study will be beneficial to accurately predict the survival of LGGs to identify patients with poor prognosis to take specific treatment as early, which will help improve the treatment outcomes and prognosis of LGG.

ALKBH5-mediated upregulation of CPT1A promotes macrophage fatty acid metabolism and M2 macrophage polarization, facilitating malignant progression of colorectal cancer

m6A modification has been studied in tumors, but its role in host anti-tumor immune response and TAMs polarization remains unclear. The fatty acid oxidation (FAO) process of TAMs is also attracting attention. A co-culture model of colorectal cancer (CRC) cells and macrophages was used to simulate the tumor microenvironment. Expression changes of m6A demethylase genes FTO and ALKBH5 were screened. ALKBH5 was further investigated. Gain-of-function experiments were conducted to study ALKBH5's effects on macrophage M2 polarization, CRC cell viability, proliferation, migration, and more. Me-RIP and Actinomycin D assays were performed to study ALKBH5's influence on CPT1A, the FAO rate-limiting enzyme. AMP, ADP, and ATP content detection, OCR measurement, and ECAR measurement were used to explore ALKBH5's impact on macrophage FAO level. Rescue experiments validated ALKBH5's mechanistic role in macrophage M2 polarization and CRC malignant development. In co-culture, CRC cells enhance macrophage FAO and suppress m6A modification in M2 macrophages. ALKBH5 was selected as the gene for further investigation. ALKBH5 mediates CPT1A upregulation by removing m6A modification, promoting M2 macrophage polarization and facilitating CRC development. These findings indicate that ALKBH5 enhances fatty acid metabolism and M2 polarization of macrophages by upregulating CPT1A, thereby promoting CRC development.

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.

Epigenetic targeting of autophagy for cancer: DNA and RNA methylation

Autophagy, a crucial cellular mechanism responsible for degradation and recycling of intracellular components, is modulated by an intricate network of molecular signals. Its paradoxical involvement in oncogenesis, acting as both a tumor suppressor and promoter, has been underscored in recent studies. Central to this regulatory network are the epigenetic modifications of DNA and RNA methylation, notably the presence of N6-methyldeoxyadenosine (6mA) in genomic DNA and N6-methyladenosine (m6A) in eukaryotic mRNA. The 6mA modification in genomic DNA adds an extra dimension of epigenetic regulation, potentially impacting the transcriptional dynamics of genes linked to autophagy and, especially, cancer. Conversely, m6A modification, governed by methyltransferases and demethylases, influences mRNA stability, processing, and translation, affecting genes central to autophagic pathways. As we delve deeper into the complexities of autophagy regulation, the importance of these methylation modifications grows more evident. The interplay of 6mA, m6A, and autophagy points to a layered regulatory mechanism, illuminating cellular reactions to a range of conditions. This review delves into the nexus between DNA 6mA and RNA m6A methylation and their influence on autophagy in cancer contexts. By closely examining these epigenetic markers, we underscore their promise as therapeutic avenues, suggesting novel approaches for cancer intervention through autophagy modulation.

Down-regulated FTO and ALKBH5 co-operatively activates FOXO signaling through m6A methylation modification in HK2 mRNA mediated by IGF2BP2 to enhance glycolysis in colorectal cancer

BACKGROUND

N6-methyladenosine (m6A) modification is the most abundant reversible methylation modification in eukaryotes, and it is reportedly closely associated with a variety of cancers progression, including colorectal cancer (CRC). This study showed that activated lipid metabolism and glycolysis play vital roles in the occurrence and development of CRC. However, only a few studies have reported the biological mechanisms underlying this connection.

METHODS

Protein and mRNA levels of FTO and ALKBH5 were measured using western blot and qRT-PCR. The effects of FTO and ALKBH5 on cell proliferation were examined using CCK-8, colony formation, and EdU assays, and the effects on cell migration and invasion were tested using a transwell assay. m6A RNA immunoprecipitation (MeRIP) and RNA-seq was used to explore downstream target gene. RIP was performed to verify the interaction between m6A and HK2. The function of FTO and ALKBH5 in vivo was determined by xenograft in nude mice.

RESULTS

In this study, FTO and ALKBH5 were significantly down-regulated in CRC patients and cells both in vivo and in vitro in a high-fat environment. Moreover, FTO and ALKBH5 over-expression hampered cell proliferation both in vitro and in vivo. Conversely, FTO and ALKBH5 knockdown accelerated the malignant biological behaviors of CRC cells. The mechanism of action of FTO and ALKBH5 involves joint regulation of HK2, a key enzyme in glycolysis, which was identified by RNA sequencing and MeRIP-seq. Furthermore, reduced expression of FTO and ALKBH5 jointly activated the FOXO signaling pathway, which led to enhanced proliferation ability in CRC cells. IGF2BP2, as a m6A reader, positively regulated HK2 mRNA in m6A dependent manner. Additionally, down-regulation of FTO/ALKBH5 increased METTL3 and decreased METTL14 levels, further promoting CRC progression.

CONCLUSION

In conclusion, our study revealed the FTO-ALKBH5/IGF2BP2/HK2/FOXO1 axis as a mechanism of aberrant m6A modification and glycolysis regulation in CRC.

ALKBH5/YTHDF2-mediated m6A modification of circAFF2 enhances radiosensitivity of colorectal cancer by inhibiting Cullin neddylation

BACKGROUND

Circular RNA (circRNA) and N6-methyladenosine (m6A) play a critical role in tumour occurrence and development, including colorectal cancer (CRC). However, little is known about the interaction between circRNA and m6A in the radiosensitivity of CRC. Here, we investigated the role of a novel m6A-regulated circRNA in CRC.

METHODS

Differentially expressed circRNAs from radiosensitive and radioresistant CRC tissues were screened. Modifications of the selected circRNAs were examined by methylated RNA immunoprecipitation assay. Finally, the selected circRNAs were subjected to radiosensitivity assay.

RESULTS

We identified that circAFF2 is closely related to both radiosensitivity and m6A in CRC. CircAFF2 was highly expressed in patients with radiosensitive rectal cancer, and patients with high expression of circAFF2 had a better prognosis. In addition, circAFF2 can enhance the radiosensitivity of CRC cells both in vitro and in vivo. The regulation of circAFF2 involves ALKBH5-mediated demethylation, followed by its recognition and degradation via YTHDF2. Rescue experiments revealed that circAFF2 could reverse the radiosensitivity induced by ALKBH5 or YTHDF2. Mechanistically, circAFF2 binds with CAND1, promotes the binding of CAND1 to Cullin1 and inhibits its neddylation, subsequently impacting the radiosensitivity of CRC.

CONCLUSION

We identified and characterised circAFF2 as a novel m6A-modified circRNA and validated the ALKBH5/YTHDF2/circAFF2/Cullin-NEDD8 axis as a potential radiotherapy target for CRC.

Therapeutic m6A Eraser ALKBH5 mRNA-Loaded Exosome-Liposome Hybrid Nanoparticles Inhibit Progression of Colorectal Cancer in Preclinical Tumor Models

Although therapeutic targets have been developed for colorectal cancer (CRC) therapy, the therapeutic effects are not ideal and the survival rate for CRC patients remains poor. Therefore, it is crucial to recognize a specific target and develop an efficacious delivery system for CRC therapy. Herein, we demonstrate that reduced ALKBH5 mediates aberrant m⁶A modification and tumor progression in CRC. Mechanically, histone deacetylase 2-mediated H3K27 deacetylation inhibits ALKBH5 transcription in CRC, whereas ectopic ALKBH5 expression decreases tumorigenesis of CRC cells and protects mice from colitis-associated tumor development. Further, METTL14/ALKBH5/IGF2BPs combine to modulate JMJD8 stability in an m⁶A-dependent manner, which increases glycolysis and accelerates the development of CRC by enhancing the enzymatic activity of PKM2. Moreover, ALKBH5 mRNA-loaded folic acid-modified exosome-liposome hybrid nanoparticles were synthesized and significantly inhibit the progression of CRC in preclinical tumor models by modulating the ALKBH5/JMJD8/PKM2 axis and inhibiting glycolysis. Overall, our research confirms the crucial function of ALKBH5 in regulating the m⁶A status in CRC and provides a direct preclinical approach for using ALKBH5 mRNA nanotherapeutics for CRC.

METTL14 Facilitates the Metastasis of Pancreatic Carcinoma by Stabilizing LINC00941 in an m6A-IGF2BP2-Dependent Manner

Pancreatic adenocarcinoma (PC), one of the most fatal diseases, usually generates a poor prognosis in advanced stages. N6-methyladenosine modification has emerged as a crucial participant in tumor development and recurrence. Methyltransferase-like 14 (METTL14), as a core member of methyltransferases, is involved in tumor progression and metastasis. However, the potential mechanism by which METTL14 regulates long noncoding RNAs (lncRNAs) in PC remains unclear. RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation quantitative PCR (MeRIP-qPCR), and fluorescence in situ hybridization (FISH) were used to explore the underlying mechanisms. In our study, we found that METTL14 expression was upregulated in PC patients, and was associated with poor prognosis. In vitro and in vivo experiments, knocking down METTL14 suppressed tumor metastasis. RNA-seq and bioinformatics analyses were used to identify LINC00941 as the downstream target of METTL14. Mechanistically, LINC00941 was upregulated by METTL14 in an m6A-dependent way. LINC00941 was recruited and recognized by IGF2BP2. METTL14 enhanced the affinity of IGF2BP2 for LINC00941, while IGF2BP2 promoted the stabilization of LINC00941, which contributed to the migration and invasion of PC cells. Overall, our research revealed that METTL14 promoted the metastasis of PC through m6A modification of LINC00941. Targeting the METTL14-LINC00941-IGF2BP2 axis may provide promising therapeutic approaches for PC.

RNA binding protein YTHDF1 mediates bisphenol S-induced Leydig cell damage by regulating the mitochondrial pathway of BCL2 and the expression of CDK2-CyclinE1

Bisphenol S (BPS) causes reproductive adverse effects on humans and animals. However, the detailed mechanism is still unclear. This research aimed to clarify the role of RNA binding protein YTHDF1 in Leydig cell damage induced by BPS. The mouse TM3 Leydig cells were exposed to BPS of 0, 20, 40, and 80 μmol/L for 72 h. Results showed that TM3 Leydig cells apoptosis rate markedly increased in BPS exposure group. Meanwhile, the apoptosis-related molecule BCL2 protein level decreased significantly, and Caspase9, Caspase3, and BAX increased significantly. Moreover, the cell cycle was blocked in the G1/S phase, CDK2 and CyclinE1 were considerably down-regulated in BPS exposure groups, and the protein level of RNA binding protein YTHDF1 decreased sharply. Furthermore, after overexpression of YTHDF1, the cell viability significantly increased, and the apoptosis rate significantly decreased in TM3 Leydig cells. In the meantime, BCL2, CDK2, and CyclinE1 were significantly up-regulated, and BAX, Caspase9, and Caspase3 were significantly down-regulated. Conversely, interference with YTHDF1 decreased cell proliferation and promoted apoptosis. Importantly, overexpression of YTHDF1 alleviated the cell viability decrease induced by BPS, and interference with YTHDF1 exacerbated the situation. RIP assays showed that the binding of YTHDF1 to CDK2, CyclinE1, and BCL2 significantly increased after overexpressing YTHDF1. Collectively, our study suggested that YTHDF1 plays an essential role in BPS-induced TM3 Leydig cell damage by regulating CDK2-CyclinE1 and BCL2 mitochondrial pathway at the translational level.

ALKBH5 decreases SLC7A11 expression by erasing m6A modification and promotes the ferroptosis of colorectal cancer cells

BACKGROUND

Colorectal cancer (CRC) is the major subtype of gastrointestinal malignancy and involves cancer-related genes and signaling pathways to regulate ferroptosis. The present study was conducted to analyze the role of alkB homolog 5 (ALKBH5) in the ferroptosis of CRC cells and provide novel targets for CRC treatment.

METHODS

The transcriptional and protein levels of ALKBH5 and solute carrier family 7 members 11 (SLC7A11) in tissues and cells were determined by qRT-PCR and Western blot assay. HCT116 and SW620 cells were transfected with ALKBH5 overexpression vectors to determine cell viability and levels of reactive oxygen species (ROS), Fe⁺, glutathione, and glutathione peroxidase 4 using cell counting kit-8, colony formation, fluorescence probe, assay kits, and Western blot assay. The N6-methyladenosine (m6A) level and the enrichment of m6A on SLC7A11 mRNA were measured by m6A quantitative analysis and m6A methylated RNA immunoprecipitation-qPCR, and the mRNA stability was determined after actinomycin D treatment. CRC cells were treated with the combination of SLC7A11 and ALKBH5 overexpression vectors to confirm the mechanism. Nude mice were subcutaneously injected with CRC cells overexpressing ALKBH5.

RESULTS

ALKBH5 was downregulated in CRC and ALKBH5 overexpression promoted ROS release and ferroptosis. ALKBH5 erased the m6A modification on SLC7A11 mRNA to reduce the mRNA stability of SLC7A11, further reducing SLC7A11 expression. SLC7A11 overexpression reversed the promotive role of ALKBH5 overexpression in ferroptosis. ALKBH5 upregulation mitigated tumor growth in vivo.

CONCLUSIONS

ALKBH5 reduced SLC7A11 transcription by erasing m6A modification, thus promoting the ferroptosis of CRC cells.

m6A modification on the fate of colorectal cancer: functions and mechanisms of cell proliferation and tumorigenesis

N6-methyladenosine (m6A) is the most pervasive RNA modification in eukaryotic cells. The dynamic and reversible m6A modification of RNA plays a critical role in the occurrence and progression of tumors by regulating RNA metabolism, including translocation, mRNA stability or decay, pre-mRNA splicing, and lncRNA processing. Numerous studies have shown that m6A modification is involved in the development of various cancers. This review aims to summarize the significant role of m6A modification in the proliferation and tumorigenesis of CRC, as well as the potential of modulating m6A modification for tumor treatment. These findings may offer new therapeutic strategies for clinical implementation of m6A modification in CRC in the near future.