m6 A-mediated regulation of PBX1-GCH1 axis promotes gastric cancer proliferation and metastasis by elevating tetrahydrobiopterin levels

METTL5 promotes gastric cancer progression via sphingomyelin metabolism

BACKGROUND

The treatment of gastric cancer (GC) has caused an enormous social burden worldwide. Accumulating studies have reported that N6-methyladenosine (m6A) is closely related to tumor progression. METTL5 is a m6A methyltransferase that plays a pivotal role in maintaining the metabolic stability of cells. However, its aberrant regulation in GC has not been fully elucidated.

AIM

To excavate the role of METTL5 in the development of GC.

METHODS

METTL5 expression and clinicopathological characteristics were analyzed via The Cancer Genome Atlas dataset and further verified via immunohistochemistry, western blotting and real-time quantitative polymerase chain reaction in tissue microarrays and clinical samples. The tumor-promoting effect of METTL5 on HGC-27 and AGS cells was explored in vitro by Cell Counting Kit-8 assays, colony formation assays, scratch healing assays, transwell assays and flow cytometry. The tumor-promoting role of METTL5 in vivo was evaluated in a xenograft tumor model. The EpiQuik m6A RNA Methylation Quantification Kit was used for m6A quantification. Next, liquid chromatography-mass spectrometry was used to evaluate the association between METTL5 and sphingomyelin metabolism, which was confirmed by Enzyme-linked immunosorbent assay and rescue tests. In addition, we investigated whether METTL5 affects the sensitivity of GC cells to cisplatin via colony formation and transwell experiments.

RESULTS

Our research revealed substantial upregulation of METTL5, which suggested a poor prognosis of GC patients. Increased METTL5 expression indicated distant lymph node metastasis, advanced cancer stage and pathological grade. An increased level of METTL5 correlated with a high degree of m6A methylation. METTL5 markedly promotes the proliferation, migration, and invasion of GC cells in vitro. METTL5 also promotes the growth of GC in animal models. METTL5 knockdown resulted in significant changes in sphingomyelin metabolism, which implies that METTL5 may impact the development of GC via sphingomyelin metabolism. In addition, high METTL5 expression led to cisplatin resistance.

CONCLUSION

METTL5 was found to be an oncogenic driver of GC and may be a new target for therapy since it facilitates GC carcinogenesis through sphingomyelin metabolism and cisplatin resistance.

Effects of CASZ1, WNT2B and PTPRG SNPs on stroke susceptibility in the Chinese Han population

BACKGROUND

Stroke is an important cause of death and disability worldwide, ranking second in the cause of death, and it is thought to be related to genetic factors. The purpose of our study is to investigate the association between CASZ1, WNT2B and PTPRG single nucleotide polymorphisms (SNPs) and stroke risk in the Chinese population.

METHODS

We recruited 1418 volunteers, comprised of 710 stroke cases and 708 controls in this study. We used MassARRAY iPLEX GOLD method to genotype the three SNPs on CASZ1, WNT2B and PTPRG. Logistic regression was used to analyse the association between these SNPs and stroke, and odds ratios (ORs) and 95% confidence intervals (CIs) were then calculated. What's more, the interactions among SNPs were predicted by multi-factor dimensionality reduction (MDR) analysis.

RESULTS

This research demonstrated that CASZ1 rs880315 and PTPRG rs704341 were associated with reduced stroke susceptibility. More precisely, CASZ1 rs880315 was associated with reduced stroke susceptibility in people aged ≤64 years and women. PTPRG rs704341 was associated with reduced stroke susceptibility in people aged >64 years, women, non-smokers and non-drinkers. Conversely, WNT2B rs12037987 was related to elevated stroke susceptibility in people aged >64 years, women and non-smokers. In addition, CASZ1 rs880315, WNT2B rs12037987 and PTPRG rs704341 had a strong redundancy relationship.

CONCLUSION

Our study concludes that CASZ1 rs880315, WNT2B rs12037987 and PTPRG rs704341 are associated with stroke, and the study provides a basis for assessing genetic variants associated with stroke risk in the Han Chinese population.

Emerging function of main RNA methylation modifications in the immune microenvironment of digestive system tumors

Digestive system tumors have been reported in more than 25% of all cancer cases worldwide, bringing a huge burden on the healthcare system. RNA methylation modification-an important post-transcriptional modification-has become an active research area in gene regulation. It is a dynamic and reversible process involving several enzymes, such as methyltransferases, demethylases, and methylation reader proteins. This review provides insights into the role of three major methylation modifications, namely m6A, m5C, and m1A, in the development of digestive system tumors, specifically in the development of tumor immune microenvironment (TIME) of these malignancies. Abnormal methylation modification affects immunosuppression and antitumor immune response by regulating the recruitment of immune cells and the release of immune factors. Understanding the mechanisms by which RNA methylation regulates digestive system tumors will be helpful in exploring new therapeutic targets.

Ferroptosis: a new hunter of hepatocellular carcinoma

Ferroptosis is an iron ion-dependent, regulatory cell death modality driven by intracellular lipid peroxidation that plays a key role in the development of HCC. Studies have shown that various clinical agents (e.g., sorafenib) have ferroptosis inducer-like effects and can exert therapeutic effects by modulating different key factors in the ferroptosis pathway. This implies that targeting tumor cell ferroptosis may be a very promising strategy for tumor therapy. In this paper, we summarize the prerequisites and defense systems for the occurrence of ferroptosis and the regulatory targets of drug-mediated ferroptosis action in HCC, the differences and connections between ferroptosis and other programmed cell deaths. We aim to summarize the theoretical basis, classical inducers of ferroptosis and research progress of ferroptosis in HCC cells, clued to the treatment of HCC by regulating ferroptosis network. Further investigation of the specific mechanisms of ferroptosis and the development of hepatocellular carcinoma and interventions at different stages of hepatocellular carcinoma will help us to deepen our understanding of hepatocellular carcinoma, with a view to providing new and more precise preventive as well as therapeutic measures for patients.

PBX1 as a novel master regulator in cancer: Its regulation, molecular biology, and therapeutic applications

PBX1 is a critical transcription factor at the top of various cell fate-determining pathways. In cancer, PBX1 stands at the crossroads of multiple oncogenic signaling pathways and mediates responses by recruiting a broad repertoire of downstream targets. Research thus far has corroborated the involvement of PBX1 in cancer proliferation, resisting apoptosis, tumor-associated neoangiogenesis, epithelial-mesenchymal transition (EMT) and metastasis, immune evasion, genome instability, and dysregulating cellular metabolism. Recently, our understanding of the functional regulation of the PBX1 protein has advanced, as increasing evidence has depicted a regulatory network consisting of transcriptional, post-transcriptional, and post-translational levels of control mechanisms. Furthermore, accumulating studies have supported the clinical utilization of PBX1 as a prognostic or therapeutic target in cancer. Preliminary results showed that PBX1 entails vast potential as a targetable master regulator in the treatment of cancer, particularly in those with high-risk features and resistance to other therapeutic strategies. In this review, we will explore the regulation, protein-protein interactions, molecular pathways, clinical application, and future challenges of PBX1.

Endogenous chemicals guard health through inhibiting ferroptotic cell death

Ferroptosis is a new form of regulated cell death caused by iron-dependent accumulation of lethal polyunsaturated phospholipids peroxidation. It has received considerable attention owing to its putative involvement in a wide range of pathophysiological processes such as organ injury, cardiac ischemia/reperfusion, degenerative disease and its prevalence in plants, invertebrates, yeasts, bacteria, and archaea. To counter ferroptosis, living organisms have evolved a myriad of intrinsic efficient defense systems, such as cyst(e)ine-glutathione-glutathione peroxidase 4 system (cyst(e)ine-GPX4 system), guanosine triphosphate cyclohydrolase 1/tetrahydrobiopterin (BH4) system (GCH1/BH4 system), ferroptosis suppressor protein 1/coenzyme Q10 system (FSP1/CoQ10 system), and so forth. Among these, GPX4 serves as the only enzymatic protection system through the reduction of lipid hydroperoxides, while other defense systems ultimately rely on small compounds to scavenge lipid radicals and prevent ferroptotic cell death. In this article, we systematically summarize the chemical biology of lipid radical trapping process by endogenous chemicals, such as coenzyme Q10 (CoQ10), BH4, hydropersulfides, vitamin K, vitamin E, 7-dehydrocholesterol, with the aim of guiding the discovery of novel ferroptosis inhibitors.

Prognostic value of RNA methylation-related genes in gastric adenocarcinoma based on bioinformatics

Background

Gastric cancer (GC) is a malignant tumor that originates from the epithelium of the gastric mucosa and has a poor prognosis. Stomach adenocarcinoma (STAD) covers 95% of total gastric cancer. This study aimed to identify the prognostic value of RNA methylation-related genes in gastric cancer.

Methods

In this study, The Cancer Genome Atlas (TCGA)-STAD and GSE84426 cohorts were downloaded from public databases. Patients were classified by consistent cluster analysis based on prognosis-related differentially expressed RNA methylation genes Prognostic genes were obtained by differential expression, univariate Cox and least absolute shrinkage and selection operator (LASSO) analyses. The prognostic model was established and validated in the training set, test set and validation set respectively. Independent prognostic analysis was implemented. Finally, the expression of prognostic genes was affirmed by reverse transcription quantitative PCR (RT-qPCR).

Results

In total, four prognostic genes (ACTA2, SAPCD2, PDK4 and APOD) related to RNA methylation were identified and enrolled into the risk signature. The STAD patients were divided into high- and low-risk groups based on the medium value of the risk score, and patients in the high-risk group had a poor prognosis. In addition, the RNA methylation-relevant risk signature was validated in the test and validation sets, and was authenticated as a reliable independent prognostic predictor. The nomogram was constructed based on the independent predictors to predict the 1/3/5-year survival probability of STAD patients. The gene set enrichment analysis (GSEA) result suggested that the poor prognosis in the high-risk subgroup may be related to immune-related pathways. Finally, the experimental results indicated that the expression trends of RNA methylation-relevant prognostic genes in gastric cancer cells were in agreement with the result of bioinformatics.

Conclusion

Our study established a novel RNA methylation-related risk signature for STAD, which was of considerable significance for improving prognosis of STAD patients and offering theoretical support for clinical therapy.

N6-methylation in the development, diagnosis, and treatment of gastric cancer

Gastric cancer (GC) ranks third among cancers in terms of mortality rate worldwide. A clear understanding of the mechanisms underlying the genesis and progression of GC will contribute to clinical decision making. N6-methyladenosine (m6A) is the most abundant among diverse mRNA modification types and regulates multiple facets of RNA metabolism. In recent years, emerging studies have shown that m6A modifications are involved in gastric carcinoma tumorigenesis and progression and can potentially be valuable new prospects for diagnosis and prognosis. This article reviews the recent progress regarding m6A in GC.

Effects of N6-methyladenosine modification on metabolic reprogramming in digestive tract tumors

N6-methyladenosine (m6A), the most abundant RNA modification within cells, participates in various biological and pathological processes, including self-renewal, invasion and proliferation, drug resistance, and stem cell characteristics. The m6A methylation plays a crucial role in tumors by regulating multiple RNA processes such as transcription, processing, and translation. Three protein types are primarily involved in m6A methylation: methyltransferases (such as METTL3, METTL14, ZC3H13, and KIAA1429), demethylases (such as FTO, ALKBH5), and RNA-binding proteins (such as the family of YTHDF, YTHDC1, YTHDC2, and IGF2BPs). Various metabolic pathways are reprogrammed in digestive tumors to meet the heightened growth demands and sustain cellular functionality. Recent studies have highlighted the extensive impact of m6A on the regulation of digestive tract tumor metabolism, further modulating tumor initiation and progression. Our review aims to provide a comprehensive understanding of the expression patterns, functional roles, and regulatory mechanisms of m6A in digestive tract tumor metabolism-related molecules and pathways. The characterization of expression profiles of m6A regulatory factors and in-depth studies on m6A methylation in digestive system tumors may provide new directions for clinical prediction and innovative therapeutic interventions.

ALKBH5-mediated CHAC1 depletion promotes malignant progression and decreases cisplatin-induced oxidative stress in gastric cancer

The m6a demethyltransferase ALKBH5 dynamically modulates gene expression and intracellular metabolic molecules by modifying RNA m6a in cancer cells. However, ALKBH5's function in gastric cancer (GC) has remained controversial. This study demonstrates that ALKBH5 is highly expressed in GC. Silencing ALKBH5 hampers proliferation, and metastatic potential, and induces cell death in GC cells. Through a comprehensive analysis of the transcriptome and m6A sequencing, alterations in certain ALKBH5 target genes, including CHAC1, were identified. ALKBH5's demethylation effect regulates CHAC1 RNA stability, leading to reduced CHAC1 expression. Moreover, CHAC1 modulates intracellular ROS levels, influencing the chemotherapy sensitivity of gastric cancer. In summary, our study unveils the pivotal role of the ALKBH5-CHAC1-ROS axis and highlights the significance of m6A methylation in gastric cancer.

The emerging role of m6A modification of non-coding RNA in gastrointestinal cancers: a comprehensive review

Gastrointestinal (GI) cancer is a series of malignant tumors with a high incidence globally. Although approaches for tumor diagnosis and therapy have advanced substantially, the mechanisms underlying the occurrence and progression of GI cancer are still unclear. Increasing evidence supports an important role for N6-methyladenosine (m6A) modification in many biological processes, including cancer-related processes via splicing, export, degradation, and translation of mRNAs. Under distinct cancer contexts, m6A regulators have different expression patterns and can regulate or be regulated by mRNAs and non-coding RNAs, especially long non-coding RNAs. The roles of m6A in cancer development have attracted increasing attention in epigenetics research. In this review, we synthesize progress in our understanding of m6A and its roles in GI cancer, especially esophageal, gastric, and colorectal cancers. Furthermore, we clarify the mechanism by which m6A contributes to GI cancer, providing a basis for the development of diagnostic, prognostic, and therapeutic targets.

Role of N6-methyladenosine RNA modification in gastric cancer

N6-methyladenosine (m6A) RNA methylation is the most prevalent internal modification of mammalian messenger RNA. The m6A modification affects multiple aspects of RNA metabolism, including processing, splicing, export, stability, and translation through the reversible regulation of methyltransferases (Writers), demethylases (Erasers), and recognition binding proteins (Readers). Accumulating evidence indicates that altered m6A levels are associated with a variety of human cancers. Recently, dysregulation of m6A methylation was shown to be involved in the occurrence and development of gastric cancer (GC) through various pathways. Thus, elucidating the relationship between m6A and the pathogenesis of GC has important clinical implications for the diagnosis, treatment, and prognosis of GC patients. In this review, we evaluate the potential role and clinical significance of m6A-related proteins which function in GC in an m6A-dependent manner. We discuss current issues regarding m6A-targeted inhibition of GC, explore new methods for GC diagnosis and prognosis, consider new targets for GC treatment, and provide a reasonable outlook for the future of GC research.

TRIM26 promotes non-small cell lung cancer survival by inducing PBX1 degradation

The transcription factor PBX1 is regarded as an oncogene in various cancers, but its role in non-small cell lung cancer (NSCLC) and the detailed mechanism is not known. In the present study, we found that PBX1 is downregulated in NSCLC tissues and inhibits NSCLC cell proliferation and migration. Subsequently, we performed an affinity purification-coupled tandem mass spectrometry (MS/MS) and found the ubiquitin ligase TRIM26 in the PBX1 immunoprecipitates. Moreover, TRIM26 binds to and mediates PBX1 for K48-linked polyubiquitination and proteasomal degradation. Noticeably, TRIM26 activity depends on its C-terminal RING domain when it is deleted TRIM26 loses its function towards PBX1. TRIM26 further inhibits PBX1 transcriptional activity and downregulates the PBX1 downstream genes, such as RNF6. Moreover, we found that overexpression of TRIM26 significantly promotes NSCLC proliferation, colony formation, and migration in contradiction to PBX1. TRIM26 is highly expressed in NSCLC tissues and predicts poor prognosis. Lastly, the growth NSCLC xenografts is promoted by overexpression of TRIM26 but is suppressed by TRIM26 knockout. In conclusion, TRIM26 is a ubiquitin ligase of PBX1 and it promotes while PBX1 inhibits NSCLC tumor growth. TRIM26 might be a novel therapeutic target for the treatment of NSCLC.

Comprehensive overview of the role of PBX1 in mammalian kidneys

Pre-B-cell leukemia homeobox transcription factor 1 (PBX1) is a member of the TALE (three-amino acid loop extension) family and functions as a homeodomain transcription factor (TF). When dimerized with other TALE proteins, it can act as a pioneer factor and provide regulatory sequences via interaction with partners. In vertebrates, PBX1 is expressed during the blastula stage, and its germline variations in humans are interrelated with syndromic anomalies of the kidney, which plays an important role in hematopoiesis and immunity among vertebrates. Herein, we summarize the existing data on PBX1 functions and the impact of PBX1 on renal tumors, PBX1-deficient animal models, and blood vessels in mammalian kidneys. The data indicated that the interaction of PBX1 with different partners such as the HOX genes is responsible for abnormal proliferation and variation of the embryonic mesenchyme, while truncating variants were shown to cause milder phenotypes (mostly cryptorchidism and deafness). Although such interactions have been identified to be the cause of many defects in mammals, some phenotypic variations are yet to be understood. Thus, further research on the TALE family is required.

Spindle function and Wnt pathway inhibition by PBX1 to suppress tumor progression via downregulating DCDC2 in colorectal cancer

PBX1 is a transcription factor that regulates a variety of genes, involved in intracellular lipid metabolism, cell proliferation, and other pathways. The promoting and inhibiting function of PBX1 in various cancer types was extensively discussed, however, there have been no studies on PBX1 proteins in colorectal cancer (CRC). This study aimed to reveal the anti-tumor function of PBX1 in CRC and the underlying molecular mechanism. Bioinformatics analysis revealed that PBX1 is downregulated in CRC, indicating that is a potential antioncogene in CRC. Overexpression of PBX1 suppresses tumor growth and metastasis in vitro and in vivo. Mechanistically, we found that PBX1 acted as a transcription factor that suppressed DCDC2 expression and inhibited spindle function. Moreover, the PBX1-DCDC2 axis controlled the Wnt pathway in CRC cells. Overexpression of DCDC2 restored CRC proliferation, metastasis abilities and Wnt pathway. In conclusion, this study suggests that PBX1 acts as a transcription factor to suppress DCDC2 expression and inhibit cell proliferation and metastasis by disrupting spindle function and the Wnt pathway in CRC.

In Silico Investigation of the Human GTP Cyclohydrolase 1 Enzyme Reveals the Potential of Drug Repurposing Approaches towards the Discovery of Effective BH4 Therapeutics

The GTP cyclohydrolase 1 enzyme (GTPCH1) is the rate-limiting enzyme of the tetrahydrobiopterin (BH₄) biosynthetic pathway. Physiologically, BH₄ plays a crucial role as an essential cofactor for the production of catecholamine neurotransmitters, including epinephrine, norepinephrine and dopamine, as well as the gaseous signaling molecule, nitric oxide. Pathological levels of the cofactor have been reported in a number of disease states, such as inflammatory conditions, neuropathic pain and cancer. Targeting the GTPCH1 enzyme has great potential in the management of a number of disease pathologies associated with dysregulated BH₄ physiology. This study is an in silico investigation of the human GTPCH1 enzyme using virtual screening and molecular dynamic simulation to identify molecules that can be repurposed to therapeutically target the enzyme. A three-tier molecular docking protocol was employed in the virtual screening of a comprehensive library of over 7000 approved medications and nutraceuticals in order to identify hit compounds capable of binding to the GTPCH1 binding pocket with the highest affinity. Hit compounds were further verified by molecular dynamic simulation studies to provide a detailed insight regarding the stability and nature of the binding interaction. In this study, we identify a number of drugs and natural compounds with recognized anti-inflammatory, analgesic and cytotoxic effects, including the aminosalicylate olsalazine, the antiepileptic phenytoin catechol, and the phlorotannins phlorofucofuroeckol and eckol. Our results suggest that the therapeutic and clinical effects of hit compounds may be partially attributed to the inhibition of the GTPCH1 enzyme. Notably, this study offers an understanding of the off-target effects of a number of compounds and advocates the potential role of aminosalicylates in the regulation of BH₄ production in inflammatory disease states. It highlights an in silico drug repurposing approach to identify a potential means of safely targeting the BH₄ biosynthetic pathway using established therapeutic agents.

Recent Advances in RNA m6A Modification in Solid Tumors and Tumor Immunity

An analogous field to epigenetics is referred to as epitranscriptomics, which focuses on the study of post-transcriptional chemical modifications in RNA. RNA molecules, including mRNA, tRNA, rRNA, and other non-coding RNA molecules, can be edited with numerous modifications. The most prevalent modification in eukaryotic mRNA is N6-methyladenosine (m6A), which is a reversible modification found in over 7000 human genes. Recent technological advances have accelerated the characterization of these modifications, and they have been shown to play important roles in many biological processes, including pathogenic processes such as cancer. In this chapter, we discuss the role of m6A mRNA modification in cancer with a focus on solid tumor biology and immunity. m6A RNA methylation and its regulatory proteins can play context-dependent roles in solid tumor development and progression by modulating RNA metabolism to drive oncogenic or tumor-suppressive cellular pathways. m6A RNA methylation also plays dynamic roles within both immune cells and tumor cells to mediate the anti-tumor immune response. Finally, an emerging area of research within epitranscriptomics studies the role of m6A RNA methylation in promoting sensitivity or resistance to cancer therapies, including chemotherapy, targeted therapy, and immunotherapy. Overall, our understanding of m6A RNA methylation in solid tumors has advanced significantly, and continued research is needed both to fill gaps in knowledge and to identify potential areas of focus for therapeutic development.

Ferritinophagy, a form of autophagic ferroptosis: New insights into cancer treatment

Ferritinophagy, a form of autophagy, is also an important part of ferroptosis, a type of regulated cell death resulting from abnormal iron metabolism involving the production of reactive oxygen species. As ferroptosis, autophagy and cancer have been revealed, ferritinophagy has attracted increasing attention in cancer development. In this review, we discuss the latest research progress on ferroptosis, autophagy-associated ferroptosis led by ferritinophagy, the regulators of ferritinophagy and promising cancer treatments that target ferritinophagy. Ferritinophagy is at the intersection of ferroptosis and autophagy and plays a significant role in cancer development. The discussed studies provide new insights into the mechanisms of ferritinophagy and promising related treatments for cancer.

Construction of a survival nomogram for gastric cancer based on the cancer genome atlas of m6A-related genes

Objective: Based on TCGA database, a prediction model for 1-, 3-, and 5-year overall survival rates of gastric cancer (GC) patients was constructed by analyzing the critical risk factors affecting the prognosis of gastric cancer patients.

Method: Clinicopathological features as well as gene signature of GC patients were obtained from TCGA database. Patients were randomly divided into a training cohort and an internal validation cohort. Independent predictors of GC prognosis were analyzed by univariate and multivariate Cox analyses to construct nomogram. The accuracy and reliability of the model was further validated by calibration curves, ROC curves, and C-indexes, and the clinical utility of the model was analyzed by decision analysis curves.

Result: Age, sex, N stage, M stage, METTL16, RBM15, FMR1, IGFBP1, and FTO were significantly associated with the prognosis of GC patients, and these predictors were further included in the construction of nomogram. The C-indexes for the training cohort and validation set were 0.735 and 0.688, respectively. The results of the ROC curve analysis indicated that the area under the curve (AUC) exceeded 0.6 in training and validation sets at 1, 3, and 5 years.

Conclusion: We have constructed and validated a nomogram that provides individual survival condition prediction for GC patients. The prognostic model integrating gene signatures and clinicopathological characteristics would help clinicians determine the prognosis of patients with GC and develop individualized treatment plans.