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Cancer stem cells (CSCs) are a small population of less differentiated cells with robust self-renewal ability. CSCs have been recognized as the root cause of tumor initiation, progression, relapse, and drug resistance. Recent studies from us and others have highlighted that N6-methyladenosine (m6A), the most prevalent modification in mRNA, plays a crucial role in carcinogenesis and CSC homeostasis. Dysregulation of the m6A modification machinery has been implicated in CSC survival and self-renewal, thereby regulating cancer progression and therapeutic resistance. In this review, we provide an overview of the roles and molecular mechanisms of the RNA m6A modification machinery in CSC survival and self-renewal. Additionally, we summarize the currently known small-molecule inhibitors targeting the dysregulated m6A modification machinery and discuss proof-of-concept studies focusing on the efficacy of these compounds in eliminating CSCs and cancers.

Gastric cancer (GC) is one of the most common malignancies in the digestive system. Many patients are found in advanced stage and have a poor prognosis. Surgery and chemotherapy remain the main treatments for gastric cancer. N6-methyladenosine (m6A) is a hot topic in tumor research in recent years. As the most common form of RNA modification in eukaryotes, m6A can regulate various stages of the RNA cycle, including RNA splicing, processing, degradation, and translation, thereby regulating RNA expression and function, playing a critical role in various pathways such as cell differentiation, development, and metabolism. The m6A demethylase can remove methyl groups on RNA, ensuring that m6A methylation is a dynamic and reversible process. As a key enzyme in the m6A methylation process, the imbalance of m6A demethylases fat mass and obesity-associated protein (FTO), AlkB homolog 5 (ALKBH5) and ALKBH3 regulate the progression of gastric cancer through various mechanisms, which is closely related to the occurrence and development of gastric cancer. These m6A demethylases regulate the signaling pathway, alter the proliferation and invasion ability of gastric cancer cells, affect its resistance to chemotherapy drugs, participate in regulating the immune response and mitochondrial metabolism of gastric cancer, and affect the growth of gastric cancer cells. They are expected to become a novel therapeutic target. This article comprehensively summarizes the molecular mechanism of m6A demethylase involved in the occurrence and development of gastric cancer, and the relationship between its expression and function, and biological characteristics of m6A demethylase were reviewed, aiming to provide new research ideas for early diagnosis and targeted treatment of gastric cancer.

Structural and functional alterations in brain microvascular endothelial cells (BMECs) caused by oxygen-glucose deprivation (OGD) are involved in the pathogenesis of various brain disorders. AlkB homolog 5 (ALKBH5) is a primary m6A demethylase that regulates various cell processes, but its distinct roles in BMEC function remain to be clarified. In the present study, in mouse middle cerebral artery occlusion (MCAO) model, knockout of ALKBH5 reduced neurological deficits, infarct volumes and tissue apoptosis caused by ischemia/reperfusion injury. Evans blue leakage and decreased expression of the tight junction protein ZO-1 and Occludin were also attenuated by ALKBH5 knockout. During the exploration of the underlying mechanisms of the role of ALKBH5 in BMECs, we found that the expression of ALKBH5 was induced at both the mRNA and protein levels by hypoxia; however, its protein stability was impaired by OGD treatment. Knockdown of ALKBH5 expression increased total m6A levels and alleviated OGD-induced BMEC injury. At the same time, the selective ALKBH5 inhibitor Cpd 20m also exhibited a protective effect on cell injury. In contrast, overexpression of ALKBH5 increased the sensitivity of BMECs to OGD. Interestingly, the m6A sequencing data revealed that knockdown of ALKBH5altered the expression of many genes via m6A upregulation. The gene expression alterations were verified by real-time PCR. Taken together, our results suggest that ALKBH5, as well as its target genes, plays important roles in the regulation of brain microvascular endothelial cell function through its RNA demethylase activity. [Display omitted] • Knockout of ALKBH5 alleviated ischemia/reperfusion injury in a mouse MCAO model. • OGD-induced BMEC injury was regulated by ALKBH5 status. • The gene profile regulated by ALKBH5 knockdown in bEnd.3 cells was explored. [ABSTRACT FROM AUTHOR]

Background: The modification of N 6 -methyladenosine (m 6 A) is a dynamic and reversible course that might play a role in cardiovascular disease. However, the mechanisms of m 6 A modification in myocardial ischemia/reperfusion injury (MIRI) remain unclear., Methods: A mouse model of MIRI and a cell model of oxygen-glucose deprivation/reperfusion (OGD/R) HL-1 cells were employed. In an in vivo study, the total RNA m 6 A modification levels were determined by dot blot, and the key genes related to m 6 A modification were screened by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot. In an in vitro study, the effects of AlkB homolog 5 (ALKBH5), an RNA demethylase, on cell proliferation, cell injury, and apoptosis were detected by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, lactate dehydrogenase (LDH) and cardiac troponin-I (cTnI) levels, and flow cytometry. Besides, the m 6 A modification-changed and differentially expressed messenger RNA (mRNA) were determined by methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) in ALKBH5 -overexpressed HL-1 cells. Finally, the mRNA levels of the promising targeted gene were examined by RT-qPCR and its m 6 A modification levels were examined by MeRIP-qPCR., Results: Our results showed that RNA m 6 A modification was involved in MIRI, in which ALKBH5 was downregulated. Functionally, by overexpressing or silencing ALKBH5 in experimental cells, we verified its protective properties on cell proliferation, cell injury, and apoptosis in the process of MIRI. Besides, we provided a mass of latent different mRNAs with m 6 A modification variation in ALKBH5-overexpressed HL-1 cells. Mechanistically, we further screened the most potential targeted mRNAs and suggested that triple functional domain (Trio) mRNA could be upregulated by ALKBH5 by reducing m 6 A level of Trio., Conclusions: This study demonstrated that the downregulated ALKBH5 might contribute to MIRI process by increasing the m 6 A modification of Trio mRNA and downregulating Trio., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-22-1289/coif). All authors report that this work was supported by the Maoming Science and Technology Program (No. 2020KJZX003); the High-Level Hospital Construction Research Project of Maoming People’s Hospital (No. zx2020016); National Natural Science Foundation of China (82100275 to Liu NB, 81900285 to Lei LM); and the Special Project of Dengfeng Program of Guangdong Provincial People’s Hospital (Nos. DFJH201812, KJ012019119, and KJ012019423). The authors have no other conflicts of interest to declare., (2022 Annals of Translational Medicine. All rights reserved.)