Identification of genetic variants in m6A modification genes associated with pancreatic cancer risk in the Chinese population

N6-methyladenosine-associated genetic variants in NECTIN2 and HPCAL1 are risk factors for abdominal aortic aneurysm

Although N6-methyladenosine (m6A) modification has been implicated in the pathogenesis of abdominal aortic aneurysm (AAA), the relationship between m6A-associated single nucleotide polymorphisms (m6A-SNPs) and AAA remains unknown. This study used integrative multi-omics analysis and clinical validation approaches to systematically identify potential m6A-SNPs connected with AAA risk. We found that rs6859 and rs10198139 could modulate the expression of local genes, NECTIN2 and HPCAL1, respectively, which exhibited upregulation in AAA tissues, and their risk variants were significantly correlated with an increased susceptibility to AAA. Incorporating rs6859 and rs10198139 improved the efficiency of AAA risk prediction compared to the model considering only conventional risk factors. Additionally, these two SNPs were predicted to be located within the regulatory sequences, and rs6859 showed a substantial impact on m6A modification levels. Our findings suggest that m6A-SNPs rs6859 and rs10198139 confer an elevated risk of AAA, possibly by promoting local gene expression through an m6A-mediated manner.

Integrative analyses of N6-methyladenosine-associated single-nucleotide polymorphisms (m6A-SNPs) identify tumor suppressor gene AK9 in lung cancer

N6 -methyladenosine (m6 A) modification has been identified as one of the most important epigenetic regulation mechanisms in the development of human cancers. However, the association between m6 A-associated single-nucleotide polymorphisms (m6 A-SNPs) and lung cancer risk remains largely unknown. Here, we identified m6 A-SNPs and examined the association of these m6 A-SNPs with lung cancer risk in 13,793 lung cancer cases and 14,027 controls. In silico functional annotation was used to identify causal m6 A-SNPs and target genes. Furthermore, methylated RNA immunoprecipitation and quantitative real-time polymerase chain reaction (MeRIP-qPCR) assay was performed to assess the m6 A modification level of different genotypes of the causal SNP. In vitro assays were performed to validate the potential role of the target gene in lung cancer. A total of 8794 m6 A-SNPs were detected, among which 397 SNPs in nine susceptibility loci were associated with lung cancer risk, including six novel loci. Bioinformatics analyses indicated that rs1321328 in 6q21 was located around the m6 A modification site of AK9 and significantly reduced AK9 expression (β = -0.15, p = 2.78 × 10-8 ). Moreover, AK9 was significantly downregulated in lung cancer tissues than that in adjacent normal tissues of samples from the Cancer Genome Atlas and Nanjing Lung Cancer Cohort. MeRIP-qPCR assay suggested that C allele of rs1321328 could significantly decrease the m6 A modification level of AK9 compared with G allele. In vitro assays verified the tumor-suppressing role of AK9 in lung cancer. These findings shed light on the pathogenic mechanism of lung cancer susceptibility loci linked with m6 A modification.

A genetic variant in gene NDUFAF4 confers the risk of non-small cell lung cancer by perturbing hsa-miR-215 binding

Hsa-microRNA-215 (hsa-miR-215) plays multiple roles in carcinogenesis through regulating its target genes. Genetic variants in hsa-miR-215 target sites thus may affect hsa-miR-215-mRNA interactions, result in altered expression of target genes and even influence cancer susceptibility. This study aimed to investigate the associations of genetic variants which located in the binding sites of hsa-miR-215 with non-small cell lung cancer (NSCLC) susceptibility in the Chinese population and reveal the potential regulatory mechanism of functional variants in NSCLC development. The candidate genetic variants were predicted and screened through bioinformatics analysis based on the degree of complementarity of hsa-miR-215 sequences. The potential effects of genetic variants on the binding ability of hsa-miR-215 and target genes were also predicted. A case-control study with 932 NSCLC patients and 1036 healthy controls was conducted to evaluate the association of candidate genetic variants with NSCLC susceptibility, and an independent case-control study with 552 NSCLC cases and 571 controls were used to further validate the promising associations. Dual luciferase reporter gene assay was applied to explore the regulation of the genetic variants on transcription activity of target gene. Cell phenotyping experiments in vitro and RNA sequencing (RNA-seq) were then carried out to preliminarily explore the potential regulatory mechanisms of the target genes in NSCLC. A total of five candidate genetic variants located in the binding sites of hsa-miR-215 were screened. The two-stage case-control study showed that a variant rs1854268 A > T, which located in the 3' untranslated (3'UTR) region of NDUFAF4 gene, was associated with decreased risk of NSCLC (additive model, odds ratio [OR] = 0.83, 95% confidence interval [CI]: 0.75-0.92, p < 0.001). Functional annotation displayed that rs1854268 A > T might downregulate the expression of NDUFAF4 by enhancing the binding affinity of hsa-miR-215-5p to NDUFAF4 mRNA. Additionally, transient knockdown of the NDUFAF4 could inhibit lung cancer cell migration and promote lung cancer cell apoptosis. Further RNA-seq analysis revealed that the knockdown of NDUFAF4 may affect NSCLC development by downregulating the nuclear factor kappa B (NF-κB) and phosphoinositide 3 kinase-AKT (PI3K-AKT) signaling pathways. Moreover, the overexpression of CCND1 could partially attenuate the effects of NDUFAF4 knock down on lung cancer cell migration and apoptosis, indicating that CCND1 may be involved in the tumor-promoting effects of NDUFAF4 as a downstream molecule of NDUFAF4 gene. In conclusion, the genetic variant rs1854268 (A > T) on NDUFAF4 confers NSCLC susceptibility by altering the binding affinity of hsa-miR-215-5p, thus regulating the expression of NDUFAF4 and subsequently influencing downstream tumor molecules and pathways such as CCND1, NF kappa B, and PI3K-AKT signaling pathways.

The therapeutic targets of N6-methyladenosine (m6A) modifications on tumor radioresistance

Radiation therapy is an important tool for malignant tumors, and its tolerance needs to be addressed. In recent years, several studies have shown that regulators of aberrant m6A methylation play an important role in the formation, development and invasion and metastasis of tumors. A large number of studies have confirmed aberrant m6A methylation as a new target for tumour therapy, but research on whether it can play a role in tumor sensitivity to radiotherapy has not been extensive and thorough enough. Recent studies have shown that all three major enzymes of m6A methylation have significant roles in radioresistance, and that the enzymes that play a role differ in different tumor types and by different mechanisms, including regulating tumor cell stemness, affecting DNA damage and repair, and controlling the cell cycle. Therefore, elucidating the mechanisms of m6A methylation in the radiotherapy of malignant tumors is essential to counteract radioresistance, improve the efficacy of radiotherapy, and even propose targeted treatment plans for specific tumors. The latest research progress on m6A methylation and radioresistance is reviewed in this article.

N6-methyladenosine-related single-nucleotide polymorphism analyses identify oncogene RNFT2 in bladder cancer

Background

Single-nucleotide polymorphisms (SNPs) in N6-methyladenosine (m6A) related genetic locus play significant roles in tumorigenesis and development. The expression level of many oncogenes and tumour suppressor genes changed because of m6A-associated SNPs. In addition, the relationship between m6A-SNP and bladder cancer (BCa) has not been well studied.

Methods

We screened m6A-SNPs in BCa by combining m6A-SNPs data and GWAS-SNPs data. Expression quantitative trait loci (eQTL) and differential expression gene (DEGs) analyses were performed. In ring finger protein, transmembrane 2 (RNFT2), rs3088107 (C  > G) was found to have significant eQTL signals and make RNFT2 gene differentially-regulated mostly in BCa. We validated the expression level of RNFT2 in 32 pairs of BCa tissues and eight BCa cell lines by quantitative real-time PCR (qRT-PCR). Functional assays were performed to investigate the role of rs3088107 and RNFT2 in BCa in vitro.

Results

We identified 673 m6A-SNPs, which were associated with BCa. Of these m6A-SNPs, 221 showed eQTL signals, amongst which, rs3088107 in RNFT2 showed significant eQTL signals. Results of bioinformatic analyses showed that 11 genes with m6A-SNPs had a differential expression level in BCa. RNFT2 was predicted to be significantly up-regulated in BCa. The qRT-PCR results validated that RNFT2 was highly expressed in our own BCa tissues and cell lines. High expression of RNFT2 also indicated a worse overall survival. We also revealed that rs3088107 (C  > G) could inhibit the expression and m6A modification of RNFT2 by qRT-PCR, western-blot and m6A-RIP assays. Moreover, the results of functional assays indicated that RNFT2 promoted BCa cell proliferation and migration.

Conclusion

This research found that m6A-SNPs were associated with oncogene RNFT2 in BCa. Furthermore, m6A-SNPs showed great application potential as a new BCa diagnostic biomarker and prognostic indicator.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02701-z.

Research advances of N6-methyladenosine in diagnosis and therapy of pancreatic cancer

BACKGROUND

N6-methyladenosine (m6A) is the addition of a methyl group on the N6 position of adenosine and is the most prevalent and abundant epigenetic modification in eukaryote mRNA. m6A marks are added to mRNA by the m6A methyltransferase complex ("writers"), removed by m6A demethylases ("erasers"), and recognized by m6A-binding proteins ("readers"). Recent evidence has shown that the m6A modification plays a crucial role in the pathogenic mechanism and malignant progression of pancreatic cancer, with roles in cell survival, proliferation, migration, invasion, tumor metastasis, and drug resistance.

METHODS

Literature was searched in Pubmed and Web of Science for the following keywords: "N6-methyladenosine", "pancreatic cancer", "epigenetic modification", "immunotherapy".

RESULTS

Among classical m6A regulators, while METTL3, METTL14, WTAP, FTO, YTHDF2, IGF2BP1-3, hnRNPC, and NKAP are upregulated in pancreatic cancer, METTL16 and ALKBH5 are downregulated in pancreatic cancer. m6A modification has been investigated in pancreatic cancer therapy.

CONCLUSION

Dysregulated m6A and its related factors in pancreatic cancer cells and patients indicate their potential values as novel biomarkers in pancreatic cancer diagnosis and targeted therapy.

Association of N6-methyladenosine readers' genes variation and expression level with pulmonary tuberculosis

N6-Methyladenosine (m6A) is associated with many biological processes and the development of multiple diseases. The aim of this study was to analyze the association of m6A readers' genes variation, as well as their expression levels, with pulmonary tuberculosis (PTB). A total of 11 single-nucleotide polymorphisms (SNPs) in m6A readers' genes (i.e., YTHDF1 rs6122103, rs6011668, YTHDF2 rs602345, rs3738067, YTHDF3 rs7464, rs12549833, YTHDC1 rs3813832, rs17592288, rs2293596, and YTHDC2 rs6594732, and rs2416282) were genotyped by SNPscan™ technique in 457 patients with PTB and 466 normal controls. The m6A readers' genes expression levels in peripheral blood mononuclear cells (PBMCs) from 78 patients with PTB and 86 normal controls were detected by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). There was no significant association between all SNPs in YTHDF1, YTHDF2, YTHDF3, YTHDC1, and YTHDC2 genes and PTB susceptibility. The increased frequencies of YTHDF2 rs3738067 GG genotype and YTHDC1 rs3813832 CC genotype, C allele, were, respectively, found in PTB patients with hypoproteinemia and fever. YTHDC2 rs6594732 variant was significantly associated with drug-induced liver damage and sputum smear-positive, and the rs2416282 variant was significantly associated with fever in patients with PTB. Compared with controls, the YTHDF1, YTHDF2, YTHDF3, YTHDC1, and YTHDC2 mRNA levels were significantly decreased in PTB. Moreover, YTHDF1 level was negatively associated with erythrocyte sedimentation rate (ESR), and YTHDF3 and YTHDC1 levels were negatively related to alanine aminotransferase (ALT) in patients with PTB. Our results demonstrated that YTHDF1, YTHDF2, YTHDF3, YTHDC1, and YTHDC2 genes SNPs did not contribute to PTB susceptibility, while their decreased levels in patients with PTB suggested that these m6A readers might play significant roles in PTB.

Role of main RNA modifications in cancer: N6-methyladenosine, 5-methylcytosine, and pseudouridine

Cancer is one of the major diseases threatening human life and health worldwide. Epigenetic modification refers to heritable changes in the genetic material without any changes in the nucleic acid sequence and results in heritable phenotypic changes. Epigenetic modifications regulate many biological processes, such as growth, aging, and various diseases, including cancer. With the advancement of next-generation sequencing technology, the role of RNA modifications in cancer progression has become increasingly prominent and is a hot spot in scientific research. This review studied several common RNA modifications, such as N⁶-methyladenosine, 5-methylcytosine, and pseudouridine. The deposition and roles of these modifications in coding and noncoding RNAs are summarized in detail. Based on the RNA modification background, this review summarized the expression, function, and underlying molecular mechanism of these modifications and their regulators in cancer and further discussed the role of some existing small-molecule inhibitors. More in-depth studies on RNA modification and cancer are needed to broaden the understanding of epigenetics and cancer diagnosis, treatment, and prognosis.

Bibliometric analysis of N6-methyladenosine in cancer: landscapes, highlights and trending topics

Background: N6-methyladenosine (m⁶A) is crucial in cancer and is being intensively studied. Aim: This bibliometric analysis seeks a broad picture of the role of m⁶A in cancer to guide and broaden future research. Methods: Publications were retrieved from Web of Science Core Collection and PubMed from 2000 to 2021, with keywords 'm⁶A' and 'cancer', and analyzed in biblioshiny and VOSviewer. Results: A total of 1013 documents were included, and China and the USA were the top countries with close collaboration. Mechanisms and predictive biomarkers of m⁶A regulator genes were highlighted. Cross-integration of m⁶A and other research hot spots, including 'immunotherapy', 'hypoxia' and 'polymorphism', were frontiers of m⁶A in cancer. Conclusion: This bibliometric study offered an updated perspective on m⁶A in cancer.

Construction and validation of a novel prognostic model for lung squamous cell cancer based on N6-methyladenosine-related genes

Background

N6-methyladenosine (m6A) is the most prevalent modification in mRNA in biological processes and associated with various malignant tumor initiation and progression. The present study aimed to construct a prognostic risk model based on m6A-related genes (the downstream genes influenced by m6A modulators) for LUSC.

Methods

Based on TCGA, we stratified LUSC patients with and without genetic alteration of m6A modulators into altered and unaltered groups. Using univariate Cox and Lasso regression analyses, we identified prognostic m6A-related genes to construct a prognostic risk model. We then applied a multivariate Cox proportional regression model and the survival analysis to evaluate the risk model. Moreover, we performed the Receiver operating characteristic curve to assess the efficiency of the prognostic model based on TCGA and GSE43131. We analyzed the characteristics of tumor-associated immune cell infiltration in LUSC through the CIBERSORT method.

Results

Three m6A-related genes (FAM71F1, MT1E, and MYEOV) were identified as prognostic genes for LUSC. A novel prognostic risk model based on the three m6A-related genes was constructed. The multivariate Cox analysis showed that the prognostic risk model was an independent risk factor (HR = 2.44, 95% CI = 1.21~3.56, p = 0.029). Patients with a high-risk group had worse overall survival both in TCGA (p = 0.018) and GSE43131 (p = 0.00017). The 1, 2, and 3-year AUC value in TCGA was 0.662, 0.662, and 0.655, respectively; The 1, 2, and 3-year AUC value in GSE43131 was 0.724, 0.724, and 0.722, respectively. The proportion of infiltrated neutrophils in the high-risk group was higher than that in the low-risk group (p = 0.028), whereas that of resting NK cells (p = 0.002) was lower.

Conclusion

A novel prognostic risk model based on three m6A-related genes for LUSC was generated in this study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02509-1.

The Interaction Between N6-Methyladenosine Modification and Non-Coding RNAs in Gastrointestinal Tract Cancers

N⁶-methyladenosine (m⁶A) is the most common epigenetic modification of eukaryotic RNA, which can participate in the growth and development of the body and a variety of physiological and disease processes by affecting the splicing, processing, localization, transport, translation, and degradation of RNA. Increasing evidence shows that non-coding RNAs, particularly microRNA, long non-coding RNA, and circular RNA, can also regulate the RNA m⁶A modification process by affecting the expression of m⁶A-related enzymes. The interaction between m⁶A modification and non-coding RNAs provides a new perspective for the exploration of the potential mechanism of tumor genesis and development. In this review, we summarize the potential mechanisms and effects of m⁶A and non-coding RNAs in gastrointestinal tract cancers.

Aerial View of the Association Between m6A-Related LncRNAs and Clinicopathological Characteristics of Pancreatic Cancer

Pancreatic cancer is a highly malignant tumor with a poor survival prognosis. We attempted to establish a robust prognostic model to elucidate the clinicopathological association between lncRNA, which may lead to poor prognosis by influencing m6A modification, and pancreatic cancer. We investigated the lncRNAs expression level and the prognostic value in 440 PDAC patients and 171 normal tissues from GTEx, TCGA, and ICGC databases. The bioinformatic analysis and statistical analysis were used to illustrate the relationship. We implemented Pearson correlation analysis to explore the m6A-related lncRNAs, univariate Cox regression and Kaplan-Meier methods were performed to identify the seven prognostic lncRNAs signatures. We inputted them in the LASSO Cox regression to establish a prognostic model in the TCGA database, verified in the ICGC database. The AUC of the ROC curve of the training set is 0.887, while the validation set is 0.711. Each patient has calculated a risk score and divided it into low-risk and high-risk subgroups by the median value. Moreover, the model showed a robust prognostic ability in the stratification analysis of different risk subgroups, pathological grades, and recurrence events. We established a ceRNA network between lncRNAs and m6A regulators. Enrichment analysis indicated that malignancy-associated biological function and signaling pathways were enriched in the high-risk subgroup and m6A-related lncRNAs target mRNA. We have even identified small molecule drugs, such as Thapsigargin, Mepacrine, and Ellipticine, that may affect pancreatic cancer progression. We found that seven lncRNAs were highly expressed in tumor patients in the GTEx-TCGA database, and LncRNA CASC19/UCA1/LINC01094/LINC02323 were confirmed in both pancreatic cell lines and FISH relative quantity. We provided a comprehensive aerial view between m6A-related lncRNAs and pancreatic cancer’s clinicopathological characteristics, and performed experiments to verify the robustness of the prognostic model.

Non-Coding RNA m6A Modification in Cancer: Mechanisms and Therapeutic Targets

Recently, N6-methyl-adenosine (m6A) ribonucleic acid (RNA) modification, a critical and common internal RNA modification in higher eukaryotes, has generated considerable research interests. Extensive studies have revealed that non-coding RNA m6A modifications (e.g. microRNAs, long non-coding RNAs, and circular RNAs) are associated with tumorigenesis, metastasis, and other tumour characteristics; in addition, they are crucial molecular regulators of cancer progression. In this review, we discuss the relationship between non-coding RNA m6A modification and cancer progression from the perspective of various cancers. In particular, we focus on important mechanisms in tumour progression such as proliferation, apoptosis, invasion and metastasis, tumour angiogenesis. In addition, we introduce clinical applications to illustrate more vividly that non-coding RNA m6A modification has broad research prospects. With this review, we aim to summarize the latest insights and ideas into non-coding RNA m6A modification in cancer progression and targeted therapy, facilitating further research.

Genome-Wide Identification of m6A-Associated Single-Nucleotide Polymorphisms in Colorectal Cancer

Background

N6-methyladenosine (m6A)-associated single-nucleotide polymorphisms (SNPs) play important roles in cancers, with previous research suggesting potential associations between m6A-SNPs and cancer. However, the relationship between the genetic determinants of m6A modification and colorectal cancer (CRC) remains unclear.

Methods

An integrative method combining raw data and summary statistics of genome-wide association studies with expression quantitative trait loci (eQTL) and differential expression data was applied to screen potential candidate CRC-associated m6A-SNPs.

Results

A total of 402 m6A-SNPs were identified as being associated with CRC (p < 0.001), with 98 showing eQTL signals. In particular, three genes were found to harbor CRC-associated m6A-SNPs: rs178184 in NOVA1, rs35782901 in HTR4, and rs60571683 in SLCO1B3. These genes were differentially expressed in at least one publicly available dataset (p < 0.05), with NOVA1 (p = 3.41×10^-11) and HTR4 (p = 5.56×10^-7) being significantly downregulated in CRC (dataset: GSE89076), and SLCO1B3 was significantly overexpressed (datasets: GSE32323 [p = 3.27×10^-5], GSE21510 [p = 1.09×10^-6], and GSE89076 [p = 7.63×10^-6]).

Conclusion

This study identified three m6A-SNPs (rs178184, rs35782901, and rs60571683) that may be associated with CRC. However, the lack of analysis of primary CRC samples in order to further elucidate the underlying pathogenesis is a major limitation of this study. Future investigations are needed to validate these CRC-associated m6A-SNPs and explore the m6A-mediated pathogenic mechanism in CRC.

N6-methyladenosine (m6A) in pancreatic cancer: Regulatory mechanisms and future direction

N6-methyladenosine (m6A), the most abundant RNA modification in eukaryotes, plays a pivotal role in regulating many cellular and biological processes. Aberrant m6A modification has recently been involved in carcinogenesis in various cancers, including pancreatic cancer. Pancreatic cancer is one of the deadliest cancers. It is a heterogeneous malignant disease characterized by a plethora of diverse genetic and epigenetic events. Increasing evidence suggests that dysregulation of m6A regulatory factors, such as methyltransferases, demethylases, and m6A-binding proteins, profoundly affects the development and progression of pancreatic cancer. In addition, m6A regulators and m6A target transcripts may be promising early diagnostic and prognostic cancer biomarkers, as well as therapeutic targets. In this review, we highlight the biological functions and mechanisms of m6A in pancreatic cancer and discuss the potential of m6A modification in clinical applications.