Development of formaldehyde dehydrogenase-coupled assay and antibody-based assays for ALKBH5 activity evaluation

Research progress of human key DNA and RNA methylation-related enzymes assay

Gene methylation-related enzymes (GMREs) are disfunction and aberrantly expressed in a variety of cancers, such as lung, gastric, and pancreatic cancers and have important implications for human health. Therefore，it is critical for early diagnosis and therapy of tumor to develop strategies that allow rapid and sensitive quantitative and qualitative detection of GMREs. With the development of modern analytical techniques and the application of various biosensors, there are numerous methods have been developed for analysis of GMREs. Therefore, this paper provides a systematic review of the strategies for level and activity assay of various GMREs including methyltransferases and demethylase. The detection methods mainly involve immunohistochemistry, colorimetry, fluorescence, chemiluminescence, electrochemistry, etc. Then, this review also addresses the coordinated role of various detection probes, novel nanomaterials, and signal amplification methods. The aim is to highlight potential challenges in the present field, to expand the analytical application of GMREs detection strategies, and to meet the urgent need for future disease diagnosis and intervention.

Dysregulation and implications of N6-methyladenosine modification in renal cell carcinoma

Increasing evidence indicates that N6-methyladenosine (m6A) methylation modification serves important functions in biological metabolism. Dysregulation of m6A regulators is related to the progression of different malignancies, including renal cell carcinoma (RCC). Recent studies have reported preliminary findings on the influence of m6A regulator dysregulation on RCC tumorigenesis and development. However, no comprehensive review that integrates and analyzes the roles of m6A modification in RCC has been published to date. In this review, we focus on the dysregulation of m6A regulators as it relates to RCC tumorigenesis and development, as well as possible applications of m6A modification in RCC diagnosis and therapeutics.

ALKBH5 inhibits the SIRT3/ACC1 axis to regulate fatty acid metabolism via an m6A-IGF2BP1-dependent manner in cervical squamous cell carcinoma

Cervical cancer (CC) is the most common malignancy of the female reproductive system, among which cervical squamous cell carcinoma (CESC) is the most common type. The demethylase ALKBH5 has been previously revealed to be downregulated in CC tissue. N6 methyladenine (m6A) is the most common modification in eukaryotic RNAs and is involved in modulating tumour progression. Therefore, we attempted to clarify the ALKBH5 role and mechanism underlying CESC progression. In CESC, patient tissue and control tissue m6A levels were measured. Reverse transcription quantitative real-time polymerase chain reaction, western blotting and immunochemistry were used to measure ALKBH5 levels. A correlation between CESC patient survival and ALKBH5 levels was evaluated. Wound healing, transwell and colony formation assays were used to detect CESC cellular behaviours. Corresponding kits and BODIPY staining were used to detect CESC lipid metabolism. Bioinformatics, immunoprecipitation, RNA pulldown and RNA immunoprecipitation assays as well as half-life measurements were used to assess the association and mechanism of ALKBH5 with silent mating type information regulation 2 homologue 3 (SIRT3), acetyl-CoA carboxylase 1 (ACC1) and insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1). The m6A demethylase ALKBH5 was depleted in CESC tissue and cells, and a low level of ALKBH5 predicted an unfavourable prognosis in CESC patients. ALKBH5 overexpression suppressed CESC growth and lipid metabolism in vitro and CESC tumour growth in vivo, and ACC1 overexpression rescued these changes. ALKBH5 downregulated ACC1 levels in CESC cells by facilitating SIRT3 methylation to repress ACC1 deacetylation. ALKBH5 destabilized SIRT3 to downregulate SIRT3 levels in CESCs in an m6A-IGF2BP1-dependent manner. ALKBH5 demethylates and destabilizes SIRT3 in an m6A-IGF2BP1-dependent manner, repressing CESC growth, lipid metabolism and tumorigenesis by downregulating ACC1.

Emerging Mutual Regulatory Roles between m6A Modification and microRNAs

N⁶-metyladenosine (m⁶A), one of the most common RNA methylation modifications in mammals, has attracted extensive attentions owing to its regulatory roles in a variety of physiological and pathological processes. As a reversible epigenetic modification on RNAs, m⁶A is dynamically mediated by the functional interplay among the regulatory proteins of methyltransferases, demethylases and methyl-binding proteins. In recent years, it has become increasingly clear that m⁶A modification is associated with the production and function of microRNAs (miRNAs). In this review, we summarize the specific kinds of m⁶A modification methyltransferases, demethylases and methyl-binding proteins. In particular, we focus on describing the roles of m⁶A modification and its regulatory proteins in the production and function of miRNAs in a variety of pathological and physiological processes. More importantly, we further discuss the mediating mechanisms of miRNAs in m⁶A modification and its regulatory proteins during the occurrence and development of various diseases.

m6A and miRNA jointly regulate the development of breast muscles in duck embryonic stages

N6-methyladenosine (m6A) is an abundant internal mRNA modification and plays a crucial regulatory role in animal growth and development. In recent years, m6A modification has been found to play a key role in skeletal muscles. However, whether m6A modification contributes to embryonic breast muscle development of Pekin ducks has not been explored. To explore the role of m6A in embryonic breast muscle development of ducks, we performed m6A sequencing and miRNA sequencing for the breast muscle of duck embryos on the 19th (E19) and 27th (E27) days. A total of 12,717 m6A peaks were identified at E19, representing a total of 7,438 gene transcripts. A total of 14,703 m6A peaks were identified, which overlapped with the transcripts of 7,753 genes at E27. Comparing E19 and E27, we identified 2,347 differential m6A peaks, which overlapped with 1,605 m6A-modified genes (MMGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that MMGs were enriched in multiple muscle- or fat-related pathways, which was also revealed from our analysis of differentially expressed genes (DEGs). Conjoint analysis of m6A-seq and RNA-seq data showed that pathways related to β-oxidation of fatty acids and skeletal muscle development were significantly enriched, suggesting that m6A modification is involved in the regulation of fat deposition and skeletal muscle development. There were 90 upregulated and 102 downregulated miRNAs identified between the E19 and E27 stages. Through overlapping analysis of genes shared by MMGs and DEGs and the targets of differentially expressed miRNAs (DEMs), we identified six m6A-mRNA-regulated miRNAs. Finally, we found that m6A modification can regulate fat deposition and skeletal muscle development. In conclusion, our results suggest that m6A modification is a key regulator for embryonic breast muscle development and fat deposition of ducks by affecting expressions of mRNAs and miRNAs. This is the first study to comprehensively characterize the m6A patterns in the duck transcriptome. These data provide a solid basis for future work aimed at determining the potential functional roles of m6A modification in adipose deposition and muscle growth.

Detailed resume of RNA m6A demethylases

N6-Methyladenosine (m⁶A) is the most abundant internal modification in eukaryotic mRNA, playing critical role in various bioprocesses. Like other epigenetic modifications, m⁶A modification can be catalyzed by the methyltransferase complex and erased dynamically to maintain cells homeostasis. Up to now, only two m⁶A demethylases have been reported, fat mass and obesity-associated protein (FTO) and alkylation protein AlkB homolog 5 (ALKBH5), involving in a wide range of mRNA biological progress, including mRNA shearing, export, metabolism and stability. Furthermore, they participate in many significantly biological signaling pathway, and contribute to the progress and development of cancer along with other diseases. In this review, we focus on the studies about structure, inhibitors development and biological function of FTO and ALKBH5.

Modulation of DNA/RNA Methylation by Small-Molecule Modulators and Their Implications in Cancer

Chromatin is an organized complex of DNA, histone proteins, and RNA. Chromatin modifications include DNA methylation, RNA methylation, and histone acetylation and methylation. The methylation of chromatin complexes predominantly alters the regulation of gene expression, and its deregulation is associated with several human diseases including cancer. Cancer is a disease characterized by dynamic changes in the genetic and epigenetic architecture of a cell. Altered DNA methylation by DNA methyltransferases (DNMTs) and m6A RNA methylation facilitate tumor initiation and progression and thus serve as critical targets for cancer therapy. Small-molecule modulators of these epigenetic targets are at the hotspots of current cancer drug discovery research. Indeed, recent studies have led to the discovery of several chemical modulators against these targets, some of which have already gained approval for cancer therapy while others are undergoing clinical trials. In this chapter, we will focus on the role of small-molecule modulators in regulating DNA/RNA methylation and their implications in cancer.

RNA methylation in hematological malignancies and its interactions with other epigenetic modifications

Hematological malignancies are a class of malignant neoplasms attributed to abnormal differentiation of hematopoietic stem cells (HSCs). The systemic involvement, poor prognosis, chemotherapy resistance, and recurrence common in hematological malignancies urge researchers to look for novel treatment targets and mechanisms. In recent years, epigenetic abnormalities have been shown to play a vital role in tumorigenesis and progression in hematological malignancies. In addition to DNA methylation and histone modifications, which are most studied, RNA methylation has become increasingly significant. In this review, we elaborate recent advances in the understanding of RNA modification in the pathogenesis, diagnosis and molecular targeted therapies of hematological malignancies and discuss its intricate interactions with other epigenetic modifications, including DNA methylation, histone modifications and noncoding RNAs.

N6-methyladenosine RNA modification in cancer therapeutic resistance: Current status and perspectives

Several strategies, including chemotherapy and radiotherapy, have improved therapeutic outcomes among cancer patients in clinical practice. However, due to their heterogeneity, cancer cells frequently display primary or acquired therapeutic resistance, thereby resulting in treatment failure. The mechanisms underlying cancer therapeutic resistance are complex and varied. Among them, N6-methyladenosine (m6A) RNA modification has gained increasing attention as a potential determinant of therapy resistance within various cancers. In this review, we primarily describe evidence for the effect of the m6A epitranscriptome on RNA homeostasis modulation, which has been shown to alter multiple cellular pathways in cancer research and treatment. Additionally, we discuss the profiles and biological implications of m6A RNA methylation, which is undergoing intensive investigation for its effect on the control of therapeutic resistance.

METTL14 promotes the migration and invasion of breast cancer cells by modulating N6‑methyladenosine and hsa‑miR‑146a‑5p expression

Breast cancer (BC) is the most frequently diagnosed cancer and the leading cause of cancer-related death among women worldwide. Evidence indicates that posttranscriptional N6-methyladenosine (m6A) modification modulates BC development. In the present study, we assessed BC and normal tissues to investigate this connection. RNA m6A levels were determined by methylation quantification assay. The effects of methyltransferase-like 14 (METTL14) gain-of-expression or co-transfection with an m6A inhibitor on cell migration and invasion abilities were determined by Transwell assays. The levels of differentially expressed (DE) miRNAs were verified by real-time quantitative PCR (RT-qPCR). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses (KEGG) were performed to analyze potential function of target genes of the DE miRNAs. The effects of candidate miRNAs modulated by METTL14 on cell migration and invasion abilities were confirmed by Transwell assays. We demonstrated that m6A methyltransferase METTL14 was significantly upregulated in BC tissues compared with normal tissues. METTL14 gain- and loss-of-expression regulated m6A levels in MCF-7 and MDA-MB-231 cells. The cell function assays revealed that METTL14 overexpression enhanced the migration and invasion capacities of BC cells. Moreover, treatment with the m6A inhibitor suppressed this enhanced cell migration and invasion. Additionally, aberrant expression of METTL14 reshaped the miRNA profile in BC cell lines. The remodeled DE miRNA/mRNA network was found to be most enriched in cancer pathways, and DE miRNAs were enriched in cell adhesion terms. hsa-miR-146a-5p modulated by METTL14 promoted cell migration and invasion. METTL14 modulates m6A modification and hsa-miR-146a-5p expression, thereby affecting the migration and invasion of breast cancer cells.