Transfer RNA demethylase ALKBH3 promotes cancer progression via induction of tRNA-derived small RNAs

ALKBH3-mediated m1A demethylation promotes the malignant progression of acute myeloid leukemia by regulating ferroptosis through the upregulation of ATF4 expression

To investigate the role of ALKBH3 in acute myeloid leukemia (AML), we constructed an animal model of xenotransplantation of AML. Our study demonstrated that ALKBH3-mediated m1A demethylation inhibits ferroptosis in KG-1 cells by increasing ATF4 expression, thus promoting the development of AML. These findings suggest that reducing ALKBH3 expression may be a potential strategy to mitigate AML progression.

Background: Acute myeloid leukemia (AML) is characterized by the unrestrained proliferation of myeloid cells. Studies have shown that ALKBH3 is upregulated in most tumors, but the role of ALKBH3 in AML remains unclear.Methods: In this study, we investigated the function of ALKBH3 in AML cells (KG-1) by immunofluorescence, ELISA, flow cytometry, HE staining, and Western blotting.Results: Our results revealed that ALKBH3 is upregulated in AML and that the downregulation of ALKBH3 inhibited KG-1 cell proliferation and promoted cell apoptosis; at the same time, ALKBH3 upregulated ATF4 expression through m1A demethylation, and the knockdown of ATF4 resulted in increased ferrous iron content; TFR1, ACSL4, and PTGS2 expression; and ROS and MDA levels, whereas SOD and GSH levels and the expression levels of ATF4, SLC7A11, GPX4, and FTH1 decreased in KG-1 cells, thereby promoting ferroptosis. Mechanistically, ALKBH3-mediated m1A demethylation suppressed ferroptosis in KG-1 cells by increasing ATF4 expression, thereby promoting the development of AML.Conclusions: Our study indicated that reducing the expression of ALKBH3 might be a potential target for improving AML symptoms.

tRNA modifications: greasing the wheels of translation and beyond

Transfer RNA (tRNA) is one of the most abundant RNA types in cells, acting as an adaptor to bridge the genetic information in mRNAs with the amino acid sequence in proteins. Both tRNAs and small fragments processed from them play many nonconventional roles in addition to translation. tRNA molecules undergo various types of chemical modifications to ensure the accuracy and efficiency of translation and regulate their diverse functions beyond translation. In this review, we discuss the biogenesis and molecular mechanisms of tRNA modifications, including major tRNA modifications, writer enzymes, and their dynamic regulation. We also summarize the state-of-the-art technologies for measuring tRNA modification, with a particular focus on 2'-O-methylation (Nm), and discuss their limitations and remaining challenges. Finally, we highlight recent discoveries linking dysregulation of tRNA modifications with genetic diseases.

Emerging importance of m6A modification in liver cancer and its potential therapeutic role

Liver cancer refers to malignant tumors that form in the liver and is usually divided into several types, the most common of which is hepatocellular carcinoma (HCC), which originates in liver cells. Other rare types of liver cancer include intrahepatic cholangiocarcinoma (iCCA). m6A modification is a chemical modification of RNA that usually manifests as the addition of a methyl group to adenine in the RNA molecule to form N6-methyladenosine. This modification exerts a critical role in various biological processes by regulating the metabolism of RNA, affecting gene expression. Recent studies have shown that m6A modification is closely related to the occurrence and development of liver cancer, and m6A regulators can further participate in the pathogenesis of liver cancer by regulating the expression of key genes and the function of specific cells. In this review, we provided an overview of the latest advances in m6A modification in liver cancer research and explored in detail the specific functions of different m6A regulators. Meanwhile, we deeply analyzed the mechanisms and roles of m6A modification in liver cancer, aiming to provide novel insights and references for the search for potential therapeutic targets. Finally, we discussed the prospects and challenges of targeting m6A regulators in liver cancer therapy.

RNA methylation: A new promising biomaker in cancer liquid biopsy

RNA methylation is a vital epigenetic modification that regulates gene expression by influencing RNA processes such as transcription, degradation, translation, and transport. Aberrant methylation, including modifications like m6A, m5C, m1A, m7G, and m3C, is closely linked to tumorigenesis and progression. Liquid biopsy, a non-invasive technique analyzing tumor markers in body fluids, offers significant potential for early diagnosis and dynamic monitoring. In this context, RNA methylation, due to its tumor-specific properties, is emerging as a valuable marker. However, significant challenges remain in its clinical application. This review explores the roles of RNA methylation in cancer, recent advances in detection technologies, and its potential as a liquid biopsy marker in tumor management. It highlights its promising applications in cancer diagnosis, prognosis, and personalized treatment in the era of precision oncology.

Role, mechanism, and application of N6-methyladenosine in hepatobiliary carcinoma

Hepatobiliary carcinoma is a frequently occurring and highly invasive cancer within the digestive tract, known for its rapid progression. Due to its difficult diagnosis and treatment in clinical practice, hepatobiliary carcinoma is a serious threat to human life and health. In recent years, the incidence of hepatobiliary carcinoma has gradually increased. N6-methyladenosine (m6A) modification, as a reversible post-transcriptional modification of the adenosine N6 site, is one of the most important RNA modifications in eukaryotes. Emerging research indicates that m6A affects the biological process of cells through the regulation of gene expression. m6A modification also plays a key role in the occurrence and development of various cancers. This review summarizes the role and mechanism of m6A modification in hepatobiliary carcinoma, and discussed its potential clinical application, so as to provide a theoretical reference for the individualized treatment of hepatobiliary carcinoma.

RNA epigenetic modifications as dynamic biomarkers in cancer: from mechanisms to clinical translation

RNA modifications are crucial for post-transcriptional gene regulation. Research on RNA modifications has become a novel frontier of epitranscriptomics. Up to now, over 170 kinds of modifications have been identified on mRNA and diverse non-coding RNA. Three classes of proteins (writers, erasers, and readers) regulate the addition, removal, and identification of epigenetic marks, thus affecting RNA biological functions. Increasing evidence identifies the dysregulation of RNA modifications in different cancer types and the therapeutic potential of targeting RNA-modifying enzymes. The ability of RNA modifications to improve mRNA stability and translation efficacy and decrease immunogenicity has been exploited for the clinical use of mRNA cancer vaccines. This review aims to shed light on several vital cap, tail, and internal modifications of RNA with a focus on the connection between RNA epigenetic pathways and cancer pathogenesis. We further explore the clinical potential of RNA modifications as dynamic biomarkers for cancer diagnosis, prognosis, and therapeutic response prediction, addressing both technological challenges and translational opportunities. Finally, we analyze the limitations of current studies and discuss the research focus in the future.

PUS10-induced tRNA fragmentation impacts retrotransposon-driven inflammation

Pseudouridine synthases (PUSs) catalyze the isomerization of uridine (U)-to-pseudouridine (Ψ) and have emerging roles in development and disease. How PUSs adapt gene expression under stress remains mostly unexplored. We identify an unconventional role for the Ψ "writer" PUS10 impacting intracellular innate immunity. Using Pus10 knockout mice, we uncover cell-intrinsic upregulation of interferon (IFN) signaling, conferring resistance to inflammation in vivo. Pus10 loss alters tRNA-derived small RNAs (tdRs) abundance, perturbing translation and endogenous retroelements expression. These alterations promote proinflammatory RNA-DNA hybrids accumulation, potentially activating cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING). Supplementation with selected tdR pools partly rescues these effects through interactions with RNA processing factors that modulate immune responses, revealing a regulatory circuit that counteracts cell-intrinsic inflammation. By extension, we define a PUS10-specific molecular fingerprint linking its dysregulation to human autoimmune disorders, including inflammatory bowel diseases. Collectively, these findings establish PUS10 as a viral mimicry modulator, with broad implications for innate immune homeostasis and autoimmunity.

Genetic variants of m1A modification genes and the risk of neuroblastoma: novel insights from a Chinese case-control study

BACKGROUND

The N1-adenosine methylation (m1A) modification plays a significant role in various cancers. However, the functions of m1A modification genes and their variants in neuroblastoma remain to be elucidated.

METHODS

We conducted a case-control study involving 402 neuroblastoma patients and 473 cancer-free controls from China via the TaqMan genotyping method to evaluate m1A modification gene polymorphisms. Multivariate logistic regression analysis was conducted to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Additionally, expression quantitative trait locus (eQTL) analysis utilizing the Genotype-Tissue Expression database was performed to investigate the impacts of significant polymorphisms on gene expression. The relationships between gene expression and the risk and prognosis of neuroblastoma patients were further examined via publicly available datasets by using the R2 platform.

RESULTS

We found that TRMT10C rs4618204 C > T significantly decreased neuroblastoma risk (CT/TT vs. CC: adjusted OR = 0.74, 95% CI = 0.56-0.97, P = 0.030). Moreover, polymorphisms of the TRMT10C (rs3762735), TRMT6 (rs451571 and rs236110), and ALKBH3 (rs10768993 and rs2292889) genes were associated with neuroblastoma risk in specific subgroups. Complete linkage disequilibrium and eQTL analysis revealed a significant association between rs4618204 C > T and reduced expression of the TRMT10C gene. Additionally, higher expression levels of the TRMT10C gene were observed to be linked to increased risk, malignancy, and poorer prognosis in neuroblastoma patients.

CONCLUSIONS

TRMT10C rs4618204 C > T was demonstrated to be significantly associated with an increased risk of neuroblastoma and may serve as a potential molecular marker for early diagnosis. Further studies are warranted to fully elucidate the specific molecular mechanisms involved in this effect.

CLINICAL TRIAL NUMBER

Not applicable.

Targeting tRNA methyltransferases: from molecular mechanisms to drug discovery

Transfer RNA methyltransferases (tRNA MTases) catalyze site-specific methylation on tRNAs, a critical process that ensures the stability and functionality of tRNA molecules, thereby maintaining cellular homeostasis of tRNA methylation. Recent studies have illuminated the structural diversity, specific substrate recognition, and conserved catalytic mechanisms of tRNA MTases, revealing how their dysregulation contributes to various diseases, including cancers and neurodevelopmental disorders. This review integrates these advances, exploring the challenges of achieving precise substrate recognition and modification in the context of complex and specific tRNA modification landscape, while emphasizing the crucial role of tRNA MTases in disease pathogenesis. The identification of small-molecule inhibitors targeting specific tRNA MTases marks a promising step toward the development of novel therapies. With continued research into the broader biological functions and regulatory mechanisms of tRNA MTases, these insights hold great potential to drive clinical advancements and therapeutic innovations.

Cancer-Specific RNA Modifications in Tumour-Derived Extracellular Vesicles Promote Tumour Growth

RNA modifications are crucial in cellular processes, and their dysregulation is linked to diseases like cancer. Extracellular vesicles (EVs) contain various RNAs and might be susceptible to modifications, but detecting these modifications has been challenging due to the small amount of RNA in EVs. We successfully detected 22 RNA modifications in EVs using a proprietary ultra-HPLC MS/MS system. We identified reduced levels of N6-methyladenosine (m6A) in EVs derived from colon cancer tissues, which correlated with cancer recurrence. Increasing m6A levels via m6A demethylase Alkbh5 knockout suppressed the tumour-promoting effects of colorectal cancer EVs. Mechanistically, colorectal cancer-derived EVs increased tumour necrotic factor α and interleukin-6 secretion by macrophages via Toll-like receptor 8 in an m6A-dependent manner, promoting cancer cell proliferation. RNA-sequencing analysis showed that the levels of 5'-half-tRNA fragment (5'-half)-GlyGCC as well as those of m6A-modified 5'-half-GlyGCC were higher and lower, respectively, in colorectal cancer EVs than in normal colon tissue EVs. Cancer-derived EVs containing 5'-half-GlyGCC significantly promoted tumour growth, which was impeded by macrophage depletion. These findings provide evidence that cancer-specific RNA modifications are present in EVs, promoting tumour progression by regulating immune cells.

RNA modifications and their role in gene expression

Post-transcriptional RNA modifications have recently emerged as critical regulators of gene expression programs. Understanding normal tissue development and disease susceptibility requires knowledge of the various cellular mechanisms which control gene expression in multicellular organisms. Research into how different RNA modifications such as in N6-methyladenosine (m6A), inosine (I), 5-methylcytosine (m5C), pseudouridine (Ψ), 5-hydroxymethylcytosine (hm5C), N1-methyladenosine (m1A), N6,2'-O-dimethyladenosine (m6Am), 2'-O-methylation (Nm), N7-methylguanosine (m7G) etc. affect the expression of genes could be valuable. This review highlights the current understanding of RNA modification, methods used to study RNA modification, types of RNA modification, and molecular mechanisms underlying RNA modification. The role of RNA modification in modulating gene expression in both physiological and diseased states is discussed. The potential applications of RNA modification in therapeutic development are elucidated.

The role of tRNA-Derived small RNAs (tsRNAs) in pancreatic cancer and acute pancreatitis

tRNA-derived small RNAs (tsRNAs), encompassing tRNA fragments (tRFs) and tRNA-derived stress-induced RNAs (tiRNAs), represent a category of non-coding small RNAs (sncRNAs) that are increasingly recognized for their diverse biological functions. These functions include gene silencing, ribosome biogenesis, retrotransposition, and epigenetics. tsRNAs have been identified as key players in the progression of various tumors, yet their specific roles in pancreatic cancer (PC) and acute pancreatitis (AP) remain largely unexplored. Pancreatic cancer, particularly pancreatic ductal adenocarcinoma, is notorious for its high mortality rate and extremely low patient survival rate, primarily due to challenges in early diagnosis. Similarly, acute pancreatitis is a complex and significant disease. This article reviews the roles of 18 tsRNAs in PC and AP, focusing on their mechanisms of action and potential clinical applications in these two diseases. These tsRNAs influence the progression of pancreatic cancer and acute pancreatitis by modulating various pathways, including ZBP1/NLRP3, Hippo, PI3K/AKT, glycolysis/gluconeogenesis, and Wnt signaling. Notably, the dysregulation of tsRNAs is closely linked to critical clinical factors in pancreatic cancer and acute pancreatitis, such as lymph node metastasis, tumor-node-metastasis (TNM) stage, overall survival (OS), and disease-free survival (DFS). This article not only elucidates the mechanisms by which tsRNAs affect pancreatic cancer and acute pancreatitis but also explores their potential as biomarkers and therapeutic targets for pancreatic cancer. The insights provided here offer valuable references for future research, highlighting the importance of tsRNAs in the diagnosis and treatment of these challenging diseases.

The Secret Life of N1-methyladenosine: A Review on its Regulatory Functions

N1-methyladenosine (m1A) is a conserved modification on house-keeping RNAs, including tRNAs and rRNAs. With recent advancement on m1A detection and mapping, m1A is revealed to have a secret life with regulatory functions. This includes the regulation of its canonical substrate tRNAs, and expands into new territories such as tRNA fragments, mRNAs and repeat RNAs. The dynamic regulation of m1A has been shown in different biological contexts, including stress response, diet, T cell activation and aging. Interestingly, m1A can also be installed by non-enzymatic mechanisms. However, technical challenges remain in m1A site mapping; as a result, controversies have been observed across different labs or different methods. In this review we will summarize the recent development of m1A detection, its dynamic regulation, and its biological functions on diverse RNA substrates.

The functions and modifications of tRNA-derived small RNAs in cancer biology

Recent progress in noncoding RNA research has highlighted transfer RNA-derived small RNAs (tsRNAs) as key regulators of gene expression, linking them to numerous cellular functions. tsRNAs, which are produced by ribonucleases such as angiogenin and Dicer, are classified based on their size and cleavage positions. They play diverse regulatory roles at the transcriptional, post-transcriptional, and translational levels. Furthermore, tRNAs undergo various modifications that influence their biogenesis, stability, functionality, biochemical characteristics, and protein-binding affinity. tsRNAs, with their aberrant expression patterns and modifications, act as both oncogenes and tumor suppressors. This review explores the biogenetic pathways of tsRNAs and their complex roles in gene regulation. We then focus on the importance of RNA modifications in tsRNAs, evaluating their impact on the biogenesis and biological functions on tsRNAs. Furthermore, we summarize recent data indicating that tsRNAs exhibit varied expression profiles across different cancer types, highlighting their potential as innovative biomarkers and therapeutic targets. This discussion integrates both existing and new knowledge about tsRNAs, emphasizing their importance in cancer biology and clinical advancement.

New insights into tRNA-derived small RNAs in human digestive diseases

tRNA-derived small RNAs (tsRNAs) is a type of non-coding RNA that is present in large quantities in humans and exhibits high stability. It plays a crucial role in various physiological processes and diseases. In recent years, research on tsRNAs in tumors has expanded significantly, revealing its regulatory effects in non-neoplastic diseases as well. Additionally, tsRNAs has been extensively studied in the context of digestive system diseases, encompassing both digestive system tumors and non-tumor conditions. It is believed to influence the biological characteristics of diseases as well as clinical pathological features. Given its potential, tsRNAs is anticipated to have broad applications in disease diagnosis and prognosis prediction, and it is expected to emerge as a new class of biomarkers. Nevertheless, numerous issues remain that require in-depth discussion. This article presents an overview of the characteristics and roles of tsRNAs in digestive system diseases, aiming to provide a comprehensive perspective and to inspire new ideas for the diagnosis and treatment of these conditions.

Transcriptome-wide mapping of N3-methylcytidine modification at single-base resolution

3-Methylcytidine (m3C), a prevalent modification of transfer RNAs (tRNAs), was recently identified in eukaryotic messenger RNAs (mRNAs). However, its precise distribution and formation mechanisms in mRNAs remain elusive. Here, we develop a novel approach, m3C immunoprecipitation and sequencing (m3C-IP-seq), utilizing antibody enrichment to profile the m3C methylome at single-nucleotide resolution. m3C-IP-seq captures 12 cytoplasmic tRNA isoacceptors and 2 mitochondrial tRNA isoacceptors containing m3C modifications. Moreover, m3C-IP-seq permits the comprehensive profiling of m3C sites in mRNAs and long noncoding RNAs, with their presence reliant on a nuclear isoform of METTL8. A significant proportion of m3C sites is concentrated in the 3' untranslated region (3' UTR) of mRNAs and is associated with mRNA degradation. Additionally, m3C methylation is dynamic and responds to hypoxia. Collectively, our data demonstrate the widespread presence of m3C modification in the human transcriptome and provide a resource for functional studies of m3C-mediated RNA metabolism.

The Role of tRNA-Derived Small RNAs (tsRNAs) in Regulating Cell Death of Cardiovascular Diseases

Transfer RNA is a class of non-coding RNA that plays a role in amino acid translocation during protein synthesis. After specific modification, the cleaved fragment is called tRNA-derived small RNA. The advancement of bioinformatics technology has led to an increase in the visibility of small RNA derived from tRNA, and their functions in biological processes are being revealed. These include gene silencing, transcription and translation, epigenetics, and cell death. These properties have led to the implication of tsRNAs in various diseases. Although the current research mainly focuses on the role of tRNA-derived small RNA in cancer, there is mounting evidence that they are also strongly associated with cardiovascular disease, including cardiac hypertrophy, atrial fibrillation, heart failure, and myocarditis. Therefore, the regulatory role of tRNA-derived small RNA in cardiovascular disease will become an emerging therapeutic strategy. This review succinctly summarizes the characteristics, classification, and regulatory effect of tsRNA. By exploring the mechanism of tsRNA, it will provide a new tool for the diagnosis and prognosis of cardiovascular disease.

Association between TRMT61B gene polymorphism and Wilms tumor susceptibility in Chinese children

BACKGROUND

Wilms tumor is among the most common pediatric malignant tumors. Although m1A modification influences the structure and function of RNA and participates in tumorigenesis, the relationship between m1A methyltransferase TRMT61B gene polymorphisms and Wilms tumor susceptibility is unclear.

METHODS

We examined the relationship between TRMT61B gene rs4563180 G > C polymorphism (detected by TaqMan probe method) in 414 children with Wilms tumor and 1199 healthy controls. The relationship between the genotype of each sublayer and the risk of Wilms tumor was studied by stratified analysis. The GTEx database was used to analyze the influence of TRMT61B rs4563180 G > C polymorphism on mRNA expression.

RESULTS

The TRMT61B gene polymorphism significantly reduced the susceptibility to Wilms tumor (GC vs. GG: adjusted odds ratio [AOR] = 0.72, 95% confidence interval [CI] = 0.56-0.93, P = 0.012; GC/CC vs. GG: AOR = 0.76, 95% CI = 0.60-0.96, P = 0.021). GC/CC genotype had a protective effect in boys and children with stage III tumors compared with rs4563180 GG genotype. Additionally, the C allele was significantly associated with decreased mRNA expression of TRMT61B gene compared with rs4563180G allele in cultured fibroblasts (P = 3.3e - 80), EBV-transformed lymphocytes (P = 9.5e - 14), and whole blood (P = 6.0e - 12).

CONCLUSIONS

Our results confirm that TRMT61B gene is associated with the development of Wilms tumors, but its underlying mechanism requires further exploration.

RNA modification writer-based immunological profile and genomic landscape of tumor microenvironment in lung adenocarcinoma

BACKGROUND

Recent studies have highlighted the role of RNA modification, that is, the dysregulation of epitranscriptomics, in tumorigenesis and progression. The potential for undoing epigenetic changes may develop novel therapeutic and prognostic approaches. However, the roles of these RNA modifications in the tumor microenvironment (TME) are still unknown.

METHODS

We assessed the expression properties and genetic alterations of 26 RNA modification writers, including adenosine-to-inosine RNA editing, alternative polyadenylation, m1A, and m6A in 502 lung adenocarcinoma (LUAD) samples from the Cancer Genome Atlas (TCGA) datasets. Then, we used differentially expressed gene (DEGs) to develop a signature for predicting patient outcomes, which was dubbed the "writer score" for RNA-modified writers. In addition, we analyzed the association between TME features, molecular subtypes, treatment sensitivity, and immunotherapy efficacy.

RESULTS

We comprehensively evaluated the changes in multilayer RNA modification writers and identified the role of RNA modification writer expression imbalances in LUAD emergence and progression. Additionally, we constructed a risk-score model based on six LUAD prognosis-associated differentially expressed RNA modification writer genes. Kaplan-Meier (K-M) analyses revealed that the low risk-score signature had high overall patient survival. The predictive significance of the risk-score model was demonstrated using both univariate and multivariate Cox analyses. The risk-score model was positively correlated with the immune- and proliferation-related pathways. In response to anti-cancer treatment, high-risk score is related with high TMB, which has been discovered to correlate with immunotherapy effectiveness.

CONCLUSION

This study showed a strong correlation between the TME variety, level of complexity, and the four types of RNA modification writers. In addition, this scoring system could potentially predict effective immunotherapy and deepens our understanding of TME characteristics.

RNA modifications in cancer

RNA modifications are emerging as critical cancer regulators that influence tumorigenesis and progression. Key modifications, such as N6-methyladenosine (m6A) and 5-methylcytosine (m5C), are implicated in various cellular processes. These modifications are regulated by proteins that write, erase, and read RNA and modulate RNA stability, splicing, translation, and degradation. Recent studies have highlighted their roles in metabolic reprogramming, signaling pathways, and cell cycle control, which are essential for tumor proliferation and survival. Despite these scientific advances, the precise mechanisms by which RNA modifications affect cancer remain inadequately understood. This review comprehensively examines the role RNA modifications play in cancer proliferation, metastasis, and programmed cell death, including apoptosis, autophagy, and ferroptosis. It explores their effects on epithelial-mesenchymal transition (EMT) and the immune microenvironment, particularly in cancer metastasis. Furthermore, RNA modifications' potential in cancer therapies, including conventional treatments, immunotherapy, and targeted therapies, is discussed. By addressing these aspects, this review aims to bridge current research gaps and underscore the therapeutic potential of targeting RNA modifications to improve cancer treatment strategies and patient outcomes.

tRNA-derived small RNAs in disease immunity

Recently, members of a unique species of non-coding RNA, known as transfer RNA-derived small RNAs (tsRNAs) have been reported to serve multiple molecular functions, including in cells that mediate immunity. Because of their low molecular weights, tsRNAs were previously difficult to detect and were thus overlooked, until now. In this review, we delve into the biogenesis of tsRNAs and their diverse biological functions, ranging from transcriptional regulation to modulation of mRNA translation. We highlight the current evidence demonstrating their involvement in the immune response, as well as how tsRNAs modulate immunity to influence tumor growth and spread, autoimmune disease pathology and infection by pathogens. We surmise that tsRNAs are likely informative as diagnostic markers of cellular homeostasis and disease, and that therapeutic targeting of tsRNAs could be beneficial for a range of human diseases. Improved knowledge on the functions for tsRNAs in the mammalian immune system will enable us to leverage tsRNAs for their effective clinical use as treatments for human health challenges.

Synergistic combination effect of the PCA-1/ALKBH3 inhibitor HUHS015 on prostate cancer drugs in vitro and in vivo

Prostate cancer antigen-1/ALKBH3, a DNA/RNA demethylase of 3-methylcytosine, 1-methyladenine (1-meA), and 6-meA, was found in prostate cancer as an important prognostic factor. Additionally, 1-meA has been associated with other cancers. The ALKBH3 inhibitor HUHS015 was found to be effective against prostate cancer both in vitro and in vivo . Herein, we investigated the effect of HUHS015 in combination with drugs for prostate cancer approved in Japan (including bicalutamide, cisplatin, mitoxantrone, prednisolone, ifosfamide, tegafur/uracil, docetaxel, dacarbazine, and estramustine) by treating DU145 cells with around IC 50 value concentrations of these drugs for 3 days. Additionally, the cells were observed for additional 9 days after drug removal. Combination treatment with dacarbazine, estramustine, tegafur/uracil, and HUHS015 showed a slight additive effect after 3 days. After drug washout of them and mitoxantrone, the combined effects and levels were enhanced and sustained, although the effects of each treatment alone declined. HUHS015 combined with cisplatin or docetaxel elicited synergistic and sustained effects. In vivo , combining HUHS015 and docetaxel, the first chemotherapeutic agent for castration-resistant prostate cancer, showed notable effects in the DU145 xenograft model. In conclusion, HUHS015 exhibited a synergistic effect with docetaxel and drugs acting on DNA in vitro , even after drug removal. Since cancer chemotherapy is typically administered during rest periods due to its high toxicity, combining it with an ALKBH3 inhibitor could be a promising strategy for enhancing cancer treatment, as it can elicit an additive effect during treatment, allowing dosage reduction, and synergistically sustain the effect after drug washout during rest periods.

Evaluation of ALKBH2 and ALKBH3 gene regulation in patients with adult T-cell leukemia/lymphoma

BACKGROUND

Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic virus that causes malignant adult T-cell leukemia/lymphoma (ATL). Patients infected with HTLV-1 are considered HTLV-1 carriers, and a small proportion of patients progress to life-threatening ATL after a long asymptomatic phase. No antiviral agent or preventive vaccine specific for HTLV-1 infection is established in current situation. For development of countermeasures to combat HTLV-1 infection and ATL, it is essential to expand our knowledge about their pathogenesis. Recently, AlkB homolog (ALKBH) family have been shown to participate in the oncogenesis of various cancer types.

METHODS

To investigate the potential role of ALKBH family members in the pathogenesis of ATL, we analyzed their gene expression dynamics in HTLV-1-infected T-cell lines and peripheral blood mononuclear cell-derived clinical specimens obtained from asymptomatic HTLV-1 carriers and patients with acute-type ATL. Epigenetic analysis was performed to dissect the mechanisms of ALKBH3 gene regulation using cultivated cells and a public dataset.

RESULTS

The mRNA expression levels of ALKBH2 and ALKBH3 were significantly or suggestively decreased in asymptomatic HTLV-1 carriers, but reverted in acute-type ATL patients, correlating with HTLV-1 basic leucine zipper factor gene expression. Intriguingly, the pre-mRNA expression of ALKBH2 and ALKBH3 was significantly suppressed in patients infected with HTLV-1, but not in healthy controls. Epigenetic analysis was performed to dissect the mechanisms of ALKBH3 gene regulation. In vitro analysis suggested a possible relationship between DNA methylation and ALKBH3 gene expression. Investigation of a public dataset revealed that specific CpG sites exhibited characteristically regulated methylation states in HTLV-1-infected T-cell subsets.

CONCLUSION

We discovered dynamically regulated patterns of ALKBH2 and ALKBH3 gene expression in patients infected with HTLV-1, and specific CpG sites epigenetically regulated by HTLV-1 infection. This study provides novel insights into HTLV-1 infection and contributes to the elucidation of ATL pathogenesis.

Harnessing m1A modification: a new frontier in cancer immunotherapy

N1-methyladenosine (m1A) modification is an epigenetic change that occurs on RNA molecules, regulated by a suite of enzymes including methyltransferases (writers), demethylases (erasers), and m1A-recognizing proteins (readers). This modification significantly impacts the function of RNA and various biological processes by affecting the structure, stability, translation, metabolism, and gene expression of RNA. Thereby, m1A modification is closely associated with the occurrence and progression of cancer. This review aims to explore the role of m1A modification in tumor immunity. m1A affects tumor immune responses by directly regulating immune cells and indirectly modulating tumor microenvironment. Besides, we also discuss the implications of m1A-mediated metabolic reprogramming and its nexus with immune checkpoint inhibitors, unveiling promising avenues for immunotherapeutic intervention. Additionally, the m1AScore, established based on the expression patterns of m1A modification, can be used to predict tumor prognosis and guide personalized therapy. Our review underscores the significance of m1A modification as a burgeoning frontier in cancer biology and immuno-oncology, with the potential to revolutionize cancer treatment strategies.

Transfer RNAs and transfer RNA-derived small RNAs in cerebrovascular diseases

This article explores the important functions of transfer RNA and - transfer RNA derived small RNAs (tsRNAs) in cellular processes and disease pathogenesis, with a particular emphasis on their involvement in cerebrovascular disorders. It discusses the biogenesis and structure of tsRNAs, including types such as tRNA halves and tRNA-derived fragments, and their functional significance in gene regulation, stress response, and cell signaling pathways. The importance of tsRNAs in neurodegenerative diseases, cancer, and cardiovascular diseases has already been highlighted, while their role in cerebrovascular diseases is in early phase of exploration. This paper presents the latest advancements in the field of tsRNAs in cerebrovascular conditions, such as ischemic stroke, intracerebral hemorrhage, and moyamoya disease. Furthermore, revealing the aptitude of tsRNAs as biomarkers for the prediction of cerebrovascular diseases and as targets for therapeutic intervention. It provides insights into the role of tsRNAs in these conditions and proposes directions for future research.

Interplay between epigenetics, senescence and cellular redox metabolism in cancer and its therapeutic implications

There is accumulating evidence indicating a close crosstalk between key molecular events regulating cell growth and proliferation, which could profoundly impact carcinogenesis and its progression. Here we focus on reviewing observations highlighting the interplay between epigenetic modifications, irreversible cell cycle arrest or senescence, and cellular redox metabolism. Epigenetic alterations, such as DNA methylation and histone modifications, dynamically influence tumour transcriptome, thereby impacting tumour phenotype, survival, growth and spread. Interestingly, the acquisition of senescent phenotype can be triggered by epigenetic changes, acting as a double-edged sword via its ability to suppress tumorigenesis or by facilitating an inflammatory milieu conducive for cancer progression. Concurrently, an aberrant redox metabolism, which is a function of the balance between reactive oxygen species (ROS) generation and intracellular anti-oxidant defences, influences signalling cascades and genomic stability in cancer cells by serving as a critical link between epigenetics and senescence. Recognizing this intricate interconnection offers a nuanced perspective for therapeutic intervention by simultaneously targeting specific epigenetic modifications, modulating senescence dynamics, and restoring redox homeostasis.

Connecting the dots: Involvement of methyltransferase-like 3, N6-methyladenosine modification, and ferroptosis in the pathogenesis of intracerebral hemorrhage pathogenesis

Intracerebral hemorrhage is a profoundly detrimental acute cerebrovascular condition with a low overall survival rate and a high post-onset disability rate. Secondary brain injury that ensues post-ICH is the primary contributor to fatality and disability. Hence, the mitigation of brain injury during intracerebral hemorrhage progression has emerged as a crucial aspect of clinical management. N6-methyladenosine is the most pervasive, abundant, and conserved internal co-transcriptional modification of eukaryotic ribonucleic acid and is predominantly expressed in the nervous system. Methyltransferase-like 3 is a key regulatory protein that is strongly associated with the development of the nervous system and numerous neurological diseases. Ferroptosis, a form of iron-associated cell death, is a typical manifestation of neuronal apoptosis in neurological diseases and plays an important role in secondary brain damage following intracerebral hemorrhage. Therefore, this review aimed to elucidate the connection between m6A modification (particularly methyltransferase-like 3) and ferroptosis in the context of intracerebral hemorrhage to provide new insights for future intracerebral hemorrhage management approaches.

Regulatory roles of RNA methylation in vascular lesions in ocular and cardiopulmonary diseases

RNA methylation is a widespread regulatory mechanism that controls gene expression in physiological processes. In recent years, the mechanisms and functions of RNA methylation under diseased conditions have been increasingly unveiled by RNA sequencing technologies with large scale and high resolution. In this review, the fundamental concept of RNA methylation is introduced, and the common types of transcript methylation and their machineries are described. Then, the regulatory roles of RNA methylation, particularly N6-methyladenosine and 5-methylcytosine, in the vascular lesions of ocular and cardiopulmonary diseases are discussed and compared. The ocular diseases include corneal neovascularization, retinopathy of prematurity, diabetic retinopathy, and pathologic myopia; whereas the cardiopulmonary ailments involve atherosclerosis and pulmonary hypertension. This review hopes to shed light on the common regulatory mechanisms underlying the vascular lesions in these ocular and cardiopulmonary diseases, which may be conducive to developing therapeutic strategies in clinical practice.

tRNA-derived small RNAs (tsRNAs): establishing their dominance in the regulation of human cancer

The main function of transfer RNAs (tRNAs) is to carry amino acids into the ribosome and synthesize proteins under the guidance of messenger RNAs (mRNAs). In addition to this, it has been observed that tRNAs undergo precise cleavage at specific loci, giving rise to an extensive array of distinct small RNAs, termed tRNA-derived small RNAs (tsRNAs). Existing studies have shown that tsRNAs are widely present across various organisms and comprehensively regulate gene expression, aberrant expression of tsRNAs is inextricably linked to tumorigenesis and development, thus, a systematic understanding of tsRNAs is necessary. This review aims to comprehensively delineate the genesis and expression patterns of tsRNAs, elucidate their diverse functions and emphasize their prospective clinical application as biomarkers and targets for therapy. It is noteworthy that we innovatively address the roles played by tsRNAs in human cancers at the level of the hallmarks of tumorigenesis proposed by Hanahan in anticipation of a broad understanding of tsRNAs and to guide the treatment of tumors.

RNA modifications: emerging players in the regulation of reproduction and development

The intricate world of RNA modifications, collectively termed the epitranscriptome, covers over 170 identified modifications and impacts RNA metabolism and, consequently, almost all biological processes. In this review, we focus on the regulatory roles and biological functions of a panel of dominant RNA modifications (including m 6A, m 5C, Ψ, ac 4C, m 1A, and m 7G) on three RNA types-mRNA, tRNA, and rRNA-in mammalian development, particularly in the context of reproduction as well as embryonic development. We discuss in detail how those modifications, along with their regulatory proteins, affect RNA processing, structure, localization, stability, and translation efficiency. We also highlight the associations among dysfunctions in RNA modification-related proteins, abnormal modification deposition and various diseases, emphasizing the roles of RNA modifications in critical developmental processes such as stem cell self-renewal and cell fate transition. Elucidating the molecular mechanisms by which RNA modifications influence diverse developmental processes holds promise for developing innovative strategies to manage developmental disorders. Finally, we outline several unexplored areas in the field of RNA modification that warrant further investigation.

Comprehensive analysis of the relationship between RNA modification writers and immune microenvironment in head and neck squamous cell carcinoma

OBJECTIVES

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Four types of RNA modification writers (m6A, m1A, A-I editing, and APA) are widely involved in tumorigenesis and the TME. We aimed to comprehensively explore the role of the four RNA modification writers in the progression and immune microenvironment of HNSCC.

MATERIALS AND METHODS

We first obtained transcription profile data and transcriptional variation of the four types of RNA modification writers from The Cancer Genome Atlas (TCGA) database. HNSCC patients in TCGA dataset were divided into different clusters based on the four types of RNA modification writers. Univariate Cox and Least absolute shrinkage and selection operator (LASSO) analyses were performed to conduct a Writer-score scoring system, which was successfully verified in the GSE65858 dataset and our clinical sample dataset. Finally, we evaluated the relationship between different RNA modification clusters (Writer-score) and immunological characteristics of HNSCC.

RESULTS

Two different RNA modification clusters (A and B) were obtained. These RNA modification clusters (Writer-score) were strongly associated with immunological characteristics (immunomodulators, cancer immunity cycles, infiltrating immune cells (TIICs), inhibitory immune checkpoints, and T cell inflamed score (TIS)) of HNSCC.

CONCLUSIONS

This study identified two different RNA modification clusters and explored the potential relationship between RNA modification clusters (Writer-score) and immunological characteristics, offering a new theoretical basis for precision immunotherapy in patients with HNSCC.

Development of a novel disulfidptosis-correlated m6A/m1A/m5C/m7G gene signature to predict prognosis and therapeutic response for lung adenocarcinoma patients by integrated machine-learning

BACKGROUND

Lung adenocarcinoma (LUAD) represents a significant global health burden, necessitating advanced prognostic tools for improved patient management. RNA modifications (m6A, m1A, m5C, m7G), and disulfidptosis, a novel cell death mechanism, have emerged as promising biomarkers and therapeutic targets in cancer.

METHODS

We systematically compiled disulfidptosis-correlated genes and RNA modification-related genes from existing literature. A novel disulfidptosis-correlated m6A/m1A/m5C/m7G riskscore was computed using integrated machine-learning algorithms. Transcriptomic data from TCGA and GEO databases were downloaded analyzed. Single-cell RNA-sequencing data from the TISCH database was processed using the Seurat package. Genes' protein-protein interaction network was constructed using the String database. Functional phenotype analysis was performed using GSVA, ClusterProfiler, and IOBR packages. Consensus clustering divided patients into two distinct groups. Drug sensitivity predictions were obtained from the GDSC1 database and predicted using the Oncopredict package.

RESULTS

The disulfidptosis-correlated m6A/m1A/m5C/m7G risk score effectively stratified LUAD patients into prognostically distinct groups, demonstrating superior predictive accuracy compared to conventional clinical parameters. Patients in different risk groups exhibited significant molecular and clinical differences. Subsequent analyses identified two molecular subtypes associated with RNA modification and disulfidptosis, revealing differences in immune infiltration and prognosis. Functional enrichment analyses highlighted pathways involving RNA modification and disulfidptosis, underscoring their roles in LUAD pathogenesis. Single-cell analysis revealed distinct features between high- and low-risk status cells.

CONCLUSION

This study introduces a novel disulfidptosis-correlated m6A/m1A/m5C/m7G risk score as a robust prognostic tool for LUAD, integrating insights from RNA modifications and cell death mechanisms. The risk score enhances prognostic stratification and identifies potential targets for personalized therapeutic strategies in LUAD. This comprehensive approach emphasizes the critical roles of RNA modifications and disulfidptosis in LUAD biology, paving the way for future research and clinical applications aimed at improving patient outcomes.

Recent insights into RNA m5C methylation modification in hepatocellular carcinoma

RNA 5-methylcytosine (m5C) methylation involves the addition of a methyl (-CH3) group to the cytosine (C) base within an RNA molecule, forming the m5C modification. m5C plays a role in numerous essential biological processes, including the regulation of RNA stability, nuclear export, and protein translation. Recent studies have highlighted the importance of m5C in the pathogenesis of various diseases, particularly tumors. Emerging evidence indicates that RNA m5C methylation is intricately implicated in the mechanisms underlying hepatocellular carcinoma (HCC). Dysregulation of m5C-associated regulatory factors is common in HCC and shows significant associations with prognosis, treatment response, and clinicopathological features. This review provides an in-depth analysis of the components and functions of m5C regulators, particularly emphasizing their research advancements in the context of HCC.

5'-tRNAGly(GCC) halves generated by IRE1α are linked to the ER stress response

Transfer RNA halves (tRHs) have various biological functions. However, the biogenesis of specific 5'-tRHs under certain conditions remains unknown. Here, we report that inositol-requiring enzyme 1α (IRE1α) cleaves the anticodon stem-loop region of tRNAGly(GCC) to produce 5'-tRHs (5'-tRH-GlyGCC) with highly selective target discrimination upon endoplasmic reticulum (ER) stress. Levels of 5'-tRH-GlyGCC positively affect cancer cell proliferation and modulate mRNA isoform biogenesis both in vitro and in vivo; these effects require co-expression of two nuclear ribonucleoproteins, HNRNPM and HNRNPH2, which we identify as binding proteins of 5'-tRH-GlyGCC. In addition, under ER stress in vivo, we observe simultaneous induction of IRE1α and 5'-tRH-GlyGCC expression in mouse organs and a distantly related organism, Cryptococcus neoformans. Thus, collectively, our findings indicate an evolutionarily conserved function for IRE1α-generated 5'-tRH-GlyGCC in cellular adaptation upon ER stress.

Decoding the epitranscriptome: a new frontier for cancer therapy and drug resistance

As the role of RNA modification in gene expression regulation and human diseases, the "epitranscriptome" has been shown to be an important player in regulating many physiological and pathological processes. Meanwhile, the phenomenon of cancer drug resistance is becoming more and more frequent, especially in the case of cancer chemotherapy resistance. In recent years, research on relationship between post-transcriptional modification and cancer including drug resistance has become a hot topic, especially the methylation of the sixth nitrogen site of RNA adenosine-m6A (N6-methyladenosine). m6A modification is the most common post-transcriptional modification of eukaryotic mRNA, accounting for 80% of RNA methylation modifications. At the same time, several other modifications of RNA, such as N1-methyladenosine (m1A), 5-methylcytosine (m5C), 3-methylcytosine (m3C), pseudouridine (Ψ) and N7-methylguanosine (m7G) have also been demonstrated to be involved in cancer and drug resistance. This review mainly discusses the research progress of RNA modifications in the field of cancer and drug resistance and targeting of m6A regulators by small molecule modulators, providing reference for future study and development of combination therapy to reverse cancer drug resistance.

tRNA and tsRNA: From Heterogeneity to Multifaceted Regulators

As the most ancient RNA, transfer RNAs (tRNAs) play a more complex role than their constitutive function as amino acid transporters in the protein synthesis process. The transcription and maturation of tRNA in cells are subject to stringent regulation, resulting in the formation of tissue- and cell-specific tRNA pools with variations in tRNA overall abundance, composition, modification, and charging levels. The heterogeneity of tRNA pools contributes to facilitating the formation of histocyte-specific protein expression patterns and is involved in diverse biological processes. Moreover, tRNAs can be recognized by various RNase under physiological and pathological conditions to generate tRNA-derived small RNAs (tsRNAs) and serve as small regulatory RNAs in various biological processes. Here, we summarize these recent insights into the heterogeneity of tRNA and highlight the advances in the regulation of tRNA function and tsRNA biogenesis by tRNA modifications. We synthesize diverse mechanisms of tRNA and tsRNA in embryonic development, cell fate determination, and epigenetic inheritance regulation. We also discuss the potential clinical applications based on the new knowledge of tRNA and tsRNA as diagnostic and prognostic biomarkers and new therapeutic strategies for multiple diseases.

Eight types of RNA modification regulators define clinical outcome and immune response in gastric cancer

Background

RNA modifications represent a novel category of biological molecule alterations, characterized by three primary classes of proteins: writers, erasers, and readers. Numerous studies indicate that the dysregulation of these RNA modifications is linked to cancer development and may offer new therapeutic avenues for treatment. In our research, we focused on eight specific genes associated with RNA modifications (RMRGs) to comprehensively analyze their distinct functions in gastric cancer (GC). Furthermore, we aimed to elucidate the roles of RMRGs concerning clinicopathological characteristics, tumor microenvironment, and patient prognosis.

Methods

In this study, we examined the expression and mutations of RMRGs in gastric cancer (GC) using data from TCGA-STAD (The Cancer Genome Atlas; Stomach adenocarcinoma) and the gene expression omnibus (GSE66229). We identified two subtypes of RMRGs and three gene clusters through consensus clustering analysis, assessing their differences in prognosis and immune cell infiltration patterns. Subsequently, we developed an RMRGs score to evaluate GC prognosis and highlight general immune features within the tumor microenvironment (TME). Lastly, we focused on MAMDC2 to validate its expression in GC and explore the effects of a MAMDC2 inhibitor on GC tumor cells.

Results

We discovered 94 differentially expressed RMRGs common to both the TCGA-STAD and GEO datasets. Notable differences in prognosis and immune cell infiltration were observed between the two RMRGs subtypes and three gene clusters. The RMRGs score emerged as an independent prognostic factor related to the tumor microenvironment (TME) characteristics in gastric cancer (GC). Reducing MAMDC2 levels enhanced cell migration and invasion while decreasing proliferation in vitro.

Conclusions

In conclusion, this study comprehensively analyzed the role of RMRGs on GC. Our study firstly proposed RMRGs score and demonstrated its potential to be biomarkers for prognosis and immune characteristics. Consequently, RMRGs score is of great clinical significance and can be utilized to develop individualized.

Clinician's Guide to Epitranscriptomics: An Example of N1-Methyladenosine (m1A) RNA Modification and Cancer

Epitranscriptomics is the study of modifications of RNA molecules by small molecular residues, such as the methyl (-CH3) group. These modifications are inheritable and reversible. A specific group of enzymes called "writers" introduces the change to the RNA; "erasers" delete it, while "readers" stimulate a downstream effect. Epitranscriptomic changes are present in every type of organism from single-celled ones to plants and animals and are a key to normal development as well as pathologic processes. Oncology is a fast-paced field, where a better understanding of tumor biology and (epi)genetics is necessary to provide new therapeutic targets and better clinical outcomes. Recently, changes to the epitranscriptome have been shown to be drivers of tumorigenesis, biomarkers, and means of predicting outcomes, as well as potential therapeutic targets. In this review, we aimed to give a concise overview of epitranscriptomics in the context of neoplastic disease with a focus on N1-methyladenosine (m1A) modification, in layman's terms, to bring closer this omics to clinicians and their future clinical practice.

Dealkylation of Macromolecules by Eukaryotic α-Ketoglutarate-Dependent Dioxygenases from the AlkB-like Family

Alkylating modifications induced by either exogenous chemical agents or endogenous metabolites are some of the main types of damage to DNA, RNA, and proteins in the cell. Although research in recent decades has been almost entirely devoted to the repair of alkyl and in particular methyl DNA damage, more and more data lately suggest that the methylation of RNA bases plays an equally important role in normal functioning and in the development of diseases. Among the most prominent participants in the repair of methylation-induced DNA and RNA damage are human homologs of Escherichia coli AlkB, nonheme Fe(II)/α-ketoglutarate-dependent dioxygenases ABH1-8, and FTO. Moreover, some of these enzymes have been found to act on several protein targets. In this review, we present up-to-date data on specific features of protein structure, substrate specificity, known roles in the organism, and consequences of disfunction of each of the nine human homologs of AlkB. Special attention is given to reports about the effects of natural single-nucleotide polymorphisms on the activity of these enzymes and to potential consequences for carriers of such natural variants.

The physiological and pathological roles of RNA modifications in T cells

RNA molecules undergo dynamic chemical modifications in response to various external or cellular stimuli. Some of those modifications have been demonstrated to post-transcriptionally modulate the RNA transcription, localization, stability, translation, and degradation, ultimately tuning the fate decisions and function of mammalian cells, particularly T cells. As a crucial part of adaptive immunity, T cells play fundamental roles in defending against infections and tumor cells. Recent findings have illuminated the importance of RNA modifications in modulating T cell survival, proliferation, differentiation, and functional activities. Therefore, understanding the epi-transcriptomic control of T cell biology enables a potential avenue for manipulating T cell immunity. This review aims to elucidate the physiological and pathological roles of internal RNA modifications in T cell development, differentiation, and functionality drawn from current literature, with the goal of inspiring new insights for future investigations and providing novel prospects for T cell-based immunotherapy.

tRNA modifications and tRNA-derived small RNAs: new insights of tRNA in human disease

tRNAs are codon decoders that convert the transcriptome into the proteome. The field of tRNA research is excited by the increasing discovery of specific tRNA modifications that are installed at specific, evolutionarily conserved positions by a set of specialized tRNA-modifying enzymes and the biogenesis of tRNA-derived regulatory fragments (tsRNAs) which exhibit copious activities through multiple mechanisms. Dysregulation of tRNA modification usually has pathological consequences, a phenomenon referred to as "tRNA modopathy". Current evidence suggests that certain tRNA-modifying enzymes and tsRNAs may serve as promising diagnostic biomarkers and therapeutic targets, particularly for chemoresistant cancers. In this review, we discuss the latest discoveries that elucidate the molecular mechanisms underlying the functions of clinically relevant tRNA modifications and tsRNAs, with a focus on malignancies. We also discuss the therapeutic potential of tRNA/tsRNA-based therapies, aiming to provide insights for the development of innovative therapeutic strategies. Further efforts to unravel the complexities inherent in tRNA biology hold the promise of yielding better biomarkers for the diagnosis and prognosis of diseases, thereby advancing the development of precision medicine for health improvement.

tsRNA modifications: An emerging layer of biological regulation in disease

BACKGROUND

Transfer RNA (tRNA)-derived small RNA (tsRNA) represents an important and increasingly valued type of small non-coding RNA (sncRNA). The investigation of tRNA and tsRNA modification crosswalks has not only provided novel insights into the information and functions of tsRNA, but has also expanded the diversity and complexity of the tsRNA biological regulation network.

AIM OF REVIEW

Comparing with other sncRNAs, tsRNA biogenesis show obvious correlation with RNA modifications from mature tRNA and harbor various tRNA modifications. In this review, we aim to present the current aspect of tsRNA modifications and that modified tsRNA shape different regulatory mechanisms in physiological and pathological processes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Strategies for studying tsRNA mechanisms include its specific generation and functional effects induced by sequence/RNA modification/secondary structure. tsRNAs could harbor more than one tRNA modifications such as 5-methylcytosine (m5C), N1-methyladenosine (m1A), pseudouridine (Ψ) and N7-methylguanosine (m7G). This review consolidates the current knowledge of tRNA modification regulating tsRNA biogenesis, outlines the functional roles of various modified tsRNA and highlights their specific contributions in various disease pathogenesis. Therefore, the improvement of tsRNA modification detection technology and the introduction of experimental methods of tsRNA modification are conducive to further broadening the understanding of tsRNA function at the level of RNA modification.

The landscape of epigenetic regulation and therapeutic application of N6-methyladenosine modifications in non-coding RNAs

RNA N6-methyladenosine (m6A) methylation is the most abundant and conserved RNA modification in eukaryotes. It participates in the regulation of RNA metabolism and various pathophysiological processes. Non-coding RNAs (ncRNAs) are defined as small or long transcripts which do not encode proteins and display numerous biological regulatory functions. Similar to mRNAs, m6A deposition is observed in ncRNAs. Studying RNA m6A modifications on ncRNAs is of great importance specifically to deepen our understanding of their biological roles and clinical implications. In this review, we summarized the recent research findings regarding the mutual regulation between RNA m6A modification and ncRNAs (with a specific focus on microRNAs, long non-coding RNAs, and circular RNAs) and their functions. We also discussed the challenges of m6A-containing ncRNAs and RNA m6A as therapeutic targets in human diseases and their future perspective in translational roles.

RNA modifications in physiology and pathology: Progressing towards application in clinical settings

The potential to modify individual nucleotides through chemical means in order to impact the electrostatic charge, hydrophobic properties, and base pairing of RNA molecules is harnessed in the medical application of stable synthetic RNAs like mRNA vaccines and synthetic small RNA molecules. These modifications are used to either increase or decrease the production of therapeutic proteins. Additionally, naturally occurring biochemical alterations of nucleotides play a role in regulating RNA metabolism and function, thereby modulating essential cellular processes. Research elucidating the mechanisms through which RNA modifications govern fundamental cellular functions in multicellular organisms has enhanced our comprehension of how irregular RNA modification profiles can lead to human diseases. Collectively, these fundamental scientific findings have unveiled the molecular and cellular functions of RNA modifications, offering new opportunities for therapeutic intervention and paving the way for a variety of innovative clinical strategies.

Methylation modifications in tRNA and associated disorders: Current research and potential therapeutic targets

High-throughput sequencing has sparked increased research interest in RNA modifications, particularly tRNA methylation, and its connection to various diseases. However, the precise mechanisms underpinning the development of these diseases remain largely elusive. This review sheds light on the roles of several tRNA methylations (m1A, m3C, m5C, m1G, m2G, m7G, m5U, and Nm) in diverse biological functions, including metabolic processing, stability, protein interactions, and mitochondrial activities. It further outlines diseases linked to aberrant tRNA modifications, related enzymes, and potential underlying mechanisms. Moreover, disruptions in tRNA regulation and abnormalities in tRNA-derived small RNAs (tsRNAs) contribute to disease pathogenesis, highlighting their potential as biomarkers for disease diagnosis. The review also delves into the exploration of drugs development targeting tRNA methylation enzymes, emphasizing the therapeutic prospects of modulating these processes. Continued research is imperative for a comprehensive comprehension and integration of these molecular mechanisms in disease diagnosis and treatment.

In vitro selection of N 1-methyladenosine-sensitive RNA-cleaving deoxyribozymes with 105-fold selectivity over unmethylated RNA

RNA-cleaving DNAzymes (RCDs) are catalytically active DNA molecules that cleave a wide range of RNA targets with extremely high sequence-selectivity, but none is able to faithfully discriminate methylated from unmethylated RNA (typically <30-fold). We report the first efforts to isolate RCDs from a random-sequence DNA pool by in vitro selection that cleave RNA/DNA chimera containing N 1-methyladenosine (m1A), one of the most prevalent RNA modifications that plays important regulatory roles in gene expression and human cancers. A cis-acting deoxyribozyme, RCD1-S2m1A, exhibits an observed rate constant (k obs) of 5.3 × 10-2 min-1, resulting in up to 105-fold faster cleavage of the m1A-modified versus unmethylated RNA. Furthermore, a trans-acting fluorogenic deoxyribozyme was constructed by labeling a fluorophore and a quencher at the 5' and 3' ends of the chimeric substrate, respectively. It permits the synchronization of RNA-cleaving with real-time fluorescence signaling, thus allowing the selective monitoring of ALKBH3-mediated demethylation and inhibitor screening in living cells.

TRMT10C gene polymorphisms confer hepatoblastoma susceptibility: evidence from a seven-center case-control study

N1-methyladenosine (m1A) is a reversible epigenetic modification of RNAs. Aberrant m1A modification levels due to dysregulation of m1A regulators have been observed in multiple cancers. tRNA methyltransferase 10C (TRMT10C) can install m1A in RNAs; however, its role in hepatoblastoma remains unknown. We conducted this study to identify causal polymorphisms in the TRMT10C gene for hepatoblastoma susceptibility in a cohort of Chinese children (313 cases vs. 1446 controls). The genotypes of four potential functional polymorphisms (rs7641261 C>T, rs2303476 T>C, rs4257518 A>G, and rs3762735 C>G) were determined in participants using TaqMan real-time PCR. The associations of these polymorphisms with hepatoblastoma susceptibility were estimated by logistic regression analysis adjusted for age and sex. All four polymorphisms were significantly associated with hepatoblastoma risk. In particular, under the recessive genetic model, these polymorphisms conferred an increased risk of hepatoblastoma: rs7641261 C>T [adjusted odds ratio (OR)=1.64, 95% confidence interval (CI)=1.04-2.58, P=0.033], rs2303476 T>C (adjusted OR=1.87, 95% CI=1.16-3.02, P=0.010), rs4257518 A>G (adjusted OR=1.45, 95% CI=1.09-1.94, P=0.012), and rs3762735 C>G (adjusted OR=3.83, 95% CI=2.15-6.82, P<0.0001). Combined analysis revealed that kids had an increased risk of developing hepatoblastoma if they harbored at least one risk genotype (adjusted OR=1.94, 95% CI=1.48-2.54, P<0.0001). In addition, the combined risk effects of the four SNPs persisted across all the subgroups. We identified four hepatoblastoma susceptibility loci in the TRMT10C gene. Identifying more disease-causing loci may facilitate the development of genetic marker panels to predict individuals' hepatoblastoma predisposition.

The potential of RNA methylation in the treatment of cardiovascular diseases

RNA methylation has emerged as a dynamic regulatory mechanism that impacts gene expression and protein synthesis. Among the known RNA methylation modifications, N6-methyladenosine (m6A), 5-methylcytosine (m5C), 3-methylcytosine (m3C), and N7-methylguanosine (m7G) have been studied extensively. In particular, m6A is the most abundant RNA modification and has attracted significant attention due to its potential effect on multiple biological processes. Recent studies have demonstrated that RNA methylation plays an important role in the development and progression of cardiovascular disease (CVD). To identify key pathogenic genes of CVD and potential therapeutic targets, we reviewed several common RNA methylation and summarized the research progress of RNA methylation in diverse CVDs, intending to inspire effective treatment strategies.

Regulations of m6A and other RNA modifications and their roles in cancer

RNA modification is an essential component of the epitranscriptome, regulating RNA metabolism and cellular functions. Several types of RNA modifications have been identified to date; they include N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N6,2'-O-dimethyladenosine (m6Am), N4-acetylcytidine (ac4C), etc. RNA modifications, mediated by regulators including writers, erasers, and readers, are associated with carcinogenesis, tumor microenvironment, metabolic reprogramming, immunosuppression, immunotherapy, chemotherapy, etc. A novel perspective indicates that regulatory subunits and post-translational modifications (PTMs) are involved in the regulation of writer, eraser, and reader functions in mediating RNA modifications, tumorigenesis, and anticancer therapy. In this review, we summarize the advances made in the knowledge of different RNA modifications (especially m6A) and focus on RNA modification regulators with functions modulated by a series of factors in cancer, including regulatory subunits (proteins, noncoding RNA or peptides encoded by long noncoding RNA) and PTMs (acetylation, SUMOylation, lactylation, phosphorylation, etc.). We also delineate the relationship between RNA modification regulator functions and carcinogenesis or cancer progression. Additionally, inhibitors that target RNA modification regulators for anticancer therapy and their synergistic effect combined with immunotherapy or chemotherapy are discussed.

PUS7-dependent pseudouridylation of ALKBH3 mRNA inhibits gastric cancer progression

BACKGROUND

RNA pseudouridylation is a critical post-transcriptional modification that influences gene expression and impacts various biological functions. Despite its significance, the role of mRNA pseudouridylation in cancer remains poorly understood. This study investigates the impact of pseudouridine synthase 7 (PUS7)-mediated pseudouridylation of Alpha-ketoglutarate-dependent Dioxygenase alkB Homolog 3 (ALKBH3) mRNA in gastric cancer.

METHODS

Immunohistochemistry and Western blotting were used to assess PUS7 protein levels in human gastric cancer tissues. The relationship between PUS7 and gastric cancer progression was examined using 3D colony formation assays and subcutaneous xenograft models. Real-time quantitative PCR (RT-qPCR), Western blotting, and polysome profiling assays were conducted to investigate how PUS7 regulates ALKBH3. A locus-specific pseudouridine (Ψ) detection assay was used to identify Ψ sites on ALKBH3 mRNA.

RESULTS

Our findings indicate a significant reduction of PUS7 in gastric cancer tissues compared to adjacent non-tumour tissues. Functional analyses reveal that PUS7 inhibits gastric cancer cell proliferation and tumour growth via its catalytic activity. Additionally, PUS7 enhances the translation efficiency of ALKBH3 mRNA by modifying the U696 site with pseudouridine, thereby attenuating tumour growth. Importantly, ALKBH3 functions as a tumour suppressor in gastric cancer, with its expression closely correlated with PUS7 levels in tumour tissues.

CONCLUSIONS

PUS7-dependent pseudouridylation of ALKBH3 mRNA enhances its translation, thereby suppressing gastric cancer progression. These findings highlight the potential significance of mRNA pseudouridylation in cancer biology and suggest a therapeutic target for gastric cancer.

HIGHLIGHTS

PUS7 enhances the translation efficiency of ALKBH3 through its pseudouridylation activity on ALKBH3 mRNA, thereby inhibiting gastric tumourigenesis. The expression levels of PUS7 and ALKBH3 are significantly correlated in gastric tumours, which may be potential prognostic predictors and therapeutic targets for patients with gastric cancer.