The m6A methyltransferase METTL3 aggravates the progression of nasopharyngeal carcinoma through inducing EMT by m6A-modified Snail mRNA

METTL14 contributes to the progression of nasopharyngeal carcinoma through regulating the stability of AOC1 mRNA

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor of the nasopharyngeal mucosa with a high incidence rate all over the world. Methyltransferase-like 14 (METTL14) is a major RNA N6-adenosine methyltransferase implicated in tumor progression by regulating RNA function. This study is designed to explore the biological function and mechanism of METTL14 in NPC.

METHODS

METTL14 and Amine oxidase copper containing 1 (AOC1) expression were detected by real-time quantitative polymerase chain reaction (RT-qPCR). The protein levels of METTL14, AOC1, Cyclin D1, B-cell lymphoma-2 (Bcl-2), and N-cadherin were measured using western blot. Cell proliferation, cycle progression, apoptosis, migration, and invasion were assessed using 5-ethynyl-2'-deoxyuridine (EdU), Colony formation, flow cytometry, wound scratch, and transwell assays. The interaction between METTL14 and AOC1 was verified using RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation (MeRIP), and dual-luciferase reporter assays. The biological role of METTL14 on NPC tumor growth was examined by the xenograft tumor model in vivo.

RESULTS

METTL14 and AOC1 were highly expressed in NPC tissues and cells. Moreover, METTL14 knockdown might block NPC cell proliferation, migration, invasion, and induce cell apoptosis in vitro. In mechanism, METTL14 might enhance the stability of AOC1 mRNA via m6A methylation. METTL14 silencing might repress NPC tumor growth in vivo.

CONCLUSION

METTL14 might boosted the development of NPC cells partly by regulating the stability of AOC1 mRNA, which provided a promising therapeutic target for NPC treatment.

LINC00313 suppresses autophagy and promotes stemness of nasopharyngeal carcinoma cells through PTBP1/STIM1 axis

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a kind of malignant head and neck tumor with high mortality. lncRNAs are valuable diagnostic biomarkers and therapeutic targets for various tumors. This study investigated the effects and mechanism of LINC00313 in nasopharyngeal carcinoma.

METHODS

Cell Counting Kit-8 (CCK-8) and immunohistochemistry were used for assessing cell proliferation. The levels of autophagy-related proteins, and stem cell markers were detected. Immunofluorescence assay was used for LC3 detection. Methylated RNA Immunoprecipitation (meRIP) of LINC00313 in NPC cells was assessed. The localization of LINC00313 was verified by luorescence in situ hybridization (FIHS). The interaction between LINC00313 and the downstream targets were analyzed and confirmed by immunoprecipitation (RIP). Besides, the tumorigenesis roles of LINC00313 were confirmed in tumor growth mice model.

RESULTS

LINC00313 was increased in NPC tissues and cells. LINC00313 knockdown enhanced autophagy, and decreased stemness and cell viability of NPC cells through regulating STIM1. METTL3/IGF2BP1-mediated m6A modification promoted the stabilization and up-regulation of LINC00313. LINC00313 activated AKT/mTOR pathway in NPC cells through PTBP1/STIM1 axis. Moreover, LINC00313 promoted tumor growth and metastasis in xenograft model.

CONCLUSION

Upregulation of LINC00313 suppressed autophagy and promoted stemness of NPC cells through PTBP1/STIM1 axis.

m 6 A reader IGF2BP1 reduces the sensitivity of nasopharyngeal carcinoma cells to Taxol by upregulation of AKT2

Taxol is widely used in the treatment of nasopharyngeal carcinoma (NPC); nevertheless, the acquired resistance of NPC to Taxol remains one of the major obstacles in clinical treatment. In this study, we aimed to investigate the role and mechanism of insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) in Taxol resistance of NPC. Taxol-resistant NPC cell lines were established by exposing to gradually increased concentration of Taxol. Relative mRNA and protein levels were tested using qRT-PCR and western blot, respectively. NPC cell viability and apoptosis were assessed by cell counting kit-8 and flow cytometry analysis, respectively. Cell migration and invasion capacities were measured using transwell assay. Interaction between IGF2BP1 and AKT2 was examined by RNA immunoprecipitation assay. The N6-methyladenosine level of AKT2 was tested using methylated RNA immunoprecipitation-qPCR. IGF2BP1 expression was enhanced in Taxol-resistant NPC cell lines. Knockdown of IGF2BP1 strikingly enhanced the sensitivity of NPC cells to Taxol and repressed the migration and invasion of NPC cells. Mechanistically, IGF2BP1 elevated the expression of AKT2 by increasing its mRNA stability. Furthermore, overexpression of AKT2 reversed the inhibitory roles of IGF2BP1 silence on Taxol resistance and metastasis. Our results indicated that IGF2BP1 knockdown enhanced the sensitivity of NPC cells to Taxol by decreasing the expression of AKT2, implying that IGF2BP1 might be promising candidate target for NPC treatment.

The m6A demethylases FTO and ALKBH5 aggravate the malignant progression of nasopharyngeal carcinoma by coregulating ARHGAP35

N6-methyladenosine (m6A) is an RNA modification that can be removed by demethylases [fat mass and obesity-associated protein (FTO) and AlkB homolog 5 (ALKBH5)], which regulate gene expression and cell function. We show that m6A levels and m6A demethylase levels are altered in nasopharyngeal carcinoma (NPC) tissues vs. normal tissues. High FTO and ALKBH5 predict a poor prognosis in NPC patients. Silencing FTO and ALKBH5 inhibited the malignant behavior of patient-derived NPC cells in a short time. However, as time progressed, the inhibitory effect of FTO or ALKBH5 was weakened, and the cosilencing of FTO and ALKBH5 maintained a better inhibitory effect. Combined transcriptome and m6A-seq analysis revealed a downstream target gene that was jointly regulated by FTO and ALKBH5 in NPC, and ARHGAP35 was chosen to do further study. The synergistic silencing of FTO and ALKBH5 increased the methylation level on the mRNA CDS of a new transcription factor (ARHGAP35) and positively regulate the protein coding capacity and mRNA stability of ARHGAP35, thus leading to increased expression of ARHGAP35 and inhibition of the malignant phenotype of tumor cells. Our study revealed that the growth and metastasis of NPC can be stably inhibited through synergistic silencing of the demethylases FTO and ALKBH5, which play a positive role in the treatment of NPC by regulating the downstream transcript ARHGAP35 and increasing its m6A level.

Epigenetic regulation of epithelial-mesenchymal transition during cancer development

Epithelial-mesenchymal transition (EMT) plays essential roles in promoting malignant transformation of epithelial cells, leading to cancer progression and metastasis. During EMT-induced cancer development, a wide variety of genes are dramatically modified, especially down-regulation of epithelial-related genes and up-regulation of mesenchymal-related genes. Expression of other EMT-related genes is also modified during the carcinogenic process. Especially, epigenetic modifications are observed in the EMT-related genes, indicating their involvement in cancer development. Mechanically, epigenetic modifications of histone, DNA, mRNA and non-coding RNA stably change the EMT-related gene expression at transcription and translation levels. Herein, we summarize current knowledge on epigenetic regulatory mechanisms observed in EMT process relate to cancer development in humans. The better understanding of epigenetic regulation of EMT during cancer development may lead to improvement of drug design and preventive strategies in cancer therapy.

Crosstalk between m6A regulators and mRNA during cancer progression

m⁶A modification, the most abundant and widespread RNA modification, is present and involved in the occurrence and development of various cancers. To date, most studies have mainly focused on the roles of a single m⁶A regulator (writer/eraser/reader) in various cancers, but cumulative evidence shows that aberrant m⁶A regulators and m⁶A levels exert dual effects (promoting and/or inhibiting roles) in cancer progression. Recently, studies have investigated the direct interactions between different m⁶A regulators (writer/eraser and reader) and mRNAs in a variety of cancers. In this review, we summarize the functions of m⁶A regulators and their roles in various types of cancers. We further propose the possible crosstalk mechanisms (Writer-m⁶A-Reader-mRNA axis and Eraser-m⁶A-Reader-mRNA axis) between different m⁶A regulators and mRNAs during cancer progression. We also discuss the clinical potential of m⁶A regulator‑targeting strategies.

Role of m6A writers, erasers and readers in cancer

The N(6)-methyladenosine (m6A) modification is the most pervasive modification of human RNAs. In recent years, an increasing number of studies have suggested that m6A likely plays important roles in cancers. Many studies have demonstrated that m6A is involved in the biological functions of cancer cells, such as proliferation, invasion, metastasis, and drug resistance. In addition, m6A is closely related to the prognosis of cancer patients. In this review, we highlight recent advances in understanding the function of m6A in various cancers. We emphasize the importance of m6A to cancer progression and look forward to describe future research directions.

miR-212-5p inhibits nasopharyngeal carcinoma progression by targeting METTL3

This study was conducted to investigate the effect of microRNA-212-5p (miR-212-5p) on the proliferation and apoptosis of nasopharyngeal carcinoma (NPC) cells. Microarray datasets (EXP00394 and EXP00660) were downloaded from the dbDEMC database, and the differentially expressed microRNAs between high-grade and low-grade NPC were analyzed. miR-212-5p and methyltransferase like 3 (METTL3) expression levels in NPC tissues and cells were determined by the quantitative real-time polymerase chain reaction and Western blot. Besides, the relationship between miR-212-5p expression and clinicopathological characteristics of patients was analyzed by the Chi-square test. Cell counting kit-8 assay, 5-ethynyl-2-deoxyuridine (EdU) assay, and flow cytometry were adopted to detect the effect of miR-212-5p on the cell proliferation and apoptosis. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analysis were performed to explore the potential biological functions and the signal pathways related to the target genes of miR-212-5p. Bioinformatics prediction and dual luciferase reporter gene assay were used to verify the relationship between miR-212-5p and METTL3 3' untranslated region. Besides, western blot was adopted to detect the expression of METTL3. Gene set enrichment analysis was performed to analyze the downstream pathways in which METTL3 was enriched. It was found that miR-212-5p was downregulated in NPC tissues, and the low miR-212-5p expression was associated with lymph node metastasis and poor differentiation. miR-212-5p overexpression inhibited the growth and promoted apoptosis of NPC cells; miR-212-5p inhibition functioned oppositely. Mechanistically, miR-212-5p inhibited the proliferation and promoted apoptosis of NPC cells via suppressing METTL3 expression. miR-212-5p/METTL3 was associated with processes of RNA transport and cell cycle. In conclusion, miR-212-5p inhibits the progression of NPC by targeting METTL3.

METTL3-mediated m6A modification promotes processing and maturation of pri-miRNA-19a to facilitate nasopharyngeal carcinoma cell proliferation and invasion

The interplay between N6-methyladenosine (m6A) modification and microRNAs (miRs) participates in cancer progression. This study is conducted to explore the role of miR-19a-3p in nasopharyngeal carcinoma (NPC) cell proliferation and invasion. RT-qPCR and western blot showed that miR-19a-3p was upregulated in NPC tissues and cells and related to poor prognosis, methyltransferase-like 3 (METTL3) was highly expressed while BMP and activin membrane-bound inhibitor (BAMBI) was weakly expressed in NPC tissues and cells. miR-19a-3p downregulation inhibited cell proliferation and invasion while miR-19a-3p overexpression played an opposite role. m6A quantification and m6A RNA immunoprecipitation assays showed that METTL3-mediated m6A modification promoted the processing and maturation of pri-miR-19a via DGCR8. Dual-luciferase assay showed that BAMBI was a target of miR-19a-3p. The rescue experiments showed that BAMBI downregulation reversed the role of miR-19a-3p inhibition in NPC cells. A xenograft tumor model showed that METTL3 downregulation inhibited tumor growth via the miR-19a-3p/BAMBI in vivo. Overall, our findings elicited that METTL3-mediated m6A modification facilitated the processing and maturation of pri-miR-19a via DGCR8 to upregulate miR-19a-3p, and miR-19a-3p inhibited BAMBI expression to promote NPC cell proliferation and invasion, thus driving NPC progression.

m6A Regulators Mediated Methylation Modification Patterns and Tumor Microenvironment Infiltration Characterization In Nasopharyngeal Carcinoma

Background

The role of RNA N6-methyladenosine (m6A) modification in tumor progression and metastasis has been demonstrated. Nonetheless, potential biological function of m6A modification patterns in nasopharyngeal carcinoma (NPC) remains unknown.

Methods

The m6A modification patterns were comprehensively evaluated based on 26 m6A regulators in NPC, and m6A subtype and also m6A score were identified and systematically correlated with representative tumor characteristics.

Results

Two distinct m6A subtypes were determined and were highly consistent with immune activated and immune suppressed phenotypes, respectively. More representative m6A scores of individual tumors could predict tumor microenvironment (TME) infiltration, mRNA based stemness index (mRNAsi), EBV gene expression, genetic variation, and prognosis of NPC patients. Low m6A score, characterized by activation of immunity and suppression of mRNAsi and EBV gene, indicated an activated TME phenotype and better PFS and also lower risk of recurrence and metastasis. High m6A score, characterized by activation of Wnt and NF-κB signaling pathway and lack of effective immune infiltration, indicated an immune suppressed TME phenotype and poorer survival. Low m6A score was also correlated with increased tumor mutation burden (TMB) and better response to immunotherapy, and vice versa. A significant therapeutic advantage in patients with low m6A score was confirmed with an anti-PDL1 immunotherapy cohort.

Conclusions

m6A patterns played an important role in the diversity and complexity of TME. m6A score could be used to evaluate the m6A pattern of individual tumor to enhance our understanding of TME infiltration and guide more effective immunotherapy strategies.

A Prognostic Risk Score Based on Hypoxia-, Immunity-, and Epithelialto-Mesenchymal Transition-Related Genes for the Prognosis and Immunotherapy Response of Lung Adenocarcinoma

Background: Lung adenocarcinoma (LUAD), the most common subtype of non-small cell lung cancer (NSCLC), is associated with poor prognosis. However, current stage-based clinical methods are insufficient for survival prediction and decision-making. This study aimed to establish a novel model for evaluating the risk of LUAD based on hypoxia, immunity, and epithelial-mesenchymal transition (EMT) gene signatures.

Methods: In this study, we used data from TCGA-LUAD for the training cohort and GSE68465 and GSE72094 for the validation cohorts. Immunotherapy datasets GSE135222, GSE126044, and IMvigor210 were obtained from a previous study. Using bioinformatic and machine algorithms, we established a risk model based on hypoxia, immune, and EMT gene signatures, which was then used to divide patients into the high and low risk groups. We analyzed differences in enriched pathways between the two groups, following which we investigated whether the risk score was correlated with stemness scores, genes related to m6A, m5C, m1A and m7G modification, the immune microenvironment, immunotherapy response, and multiple anti-cancer drug sensitivity.

Results: Overall survival differed significantly between the high-risk and low-risk groups (HR = 4.26). The AUCs for predicting 1-, 3-, and 5-year survival were 0.763, 0.766, and 0.728, respectively. In the GSE68465 dataset, the HR was 2.03, while the AUCs for predicting 1-, 3-, and 5-year survival were 0.69, 0.651, and 0.618, respectively. The corresponding values in the GSE72094 dataset were an HR of 2.36 and AUCs of 0.653, 0.662, and 0.749, respectively. The risk score model could independently predict OS in patients with LUAD, and highly correlated with stemness scores and numerous m6A, m5C, m1A and m7G modification-related genes. Furthermore, the risk model was significantly correlated with multiple immune microenvironment characteristics. In the GSE135222 dataset, the HR was 4.26 and the AUC was 0.702. Evaluation of the GSE126044 and IMvigor210 cohorts indicated that PD-1/PD-LI inhibitor treatment may be indicated in patients with low risk scores, while anti-cancer therapy with various drugs may be indicated in patients with high risk scores.

Conclusion: Our novel risk model developed based on hypoxia, immune, and EMT gene signatures can aid in predicting clinical prognosis and guiding treatment in patients with LUAD.

m6A Modification in Non-Coding RNA: The Role in Cancer Drug Resistance

Cancer drug resistance has always been a major difficulty in cancer therapy. In the face of drug pressure, resistant cancer cells show complex molecular mechanisms including epigenetic changes to maintain survival. Studies prove that cancer cells exhibit abnormal m6A modification after acquiring drug resistance. m6A modification in the target RNA including non-coding RNA can be a controller to determine the fate and metabolism of RNA by regulating their stability, subcellular localization, or translation. In particular, m6A-modified non-coding RNA plays multiple roles in multiple drug-resistant cancer cells, which can be a target for cancer drug resistance. Here, we provide an overview of the complex regulatory mechanisms of m6A-modified non-coding RNA in cancer drug resistance, and we discuss its potential value and challenges in clinical applications.

RNA m6A methyltransferase METTL3 promotes colorectal cancer cell proliferation and invasion by regulating Snail expression

Nitrogen 6-methyladenosine (m⁶A) is the result of methylation of nitrogen-6 on adenosine, and is the most abundant chemical modification of eukaryotic mRNA. Dysregulation of m⁶A methylation has been implicated in cancer development and progression through various mechanisms. This type of methylation is primarily regulated by methyltransferase-like 3 (METTL3). However, the molecular mechanisms underlying the role of METTL3 in colorectal cancer (CRC) have not been extensively elucidated. The present study explored m⁶A modification and the underlying mechanism of m⁶A, which serve regulatory roles in the development of CRC. It was found that METTL3 is upregulated in CRC cell lines and tissues, and its expression positively correlated with poor overall survival (OS). Mechanistically, the present study demonstrated that METTL3 methylates Snail mRNA, thus stabilizing it to promote CRC malignancy. The present findings indicate that m⁶A modification is involved in CRC tumorigenesis, and highlight its potential as a therapeutic target against CRC.

YTHDF1 promotes hepatocellular carcinoma progression via activating PI3K/AKT/mTOR signaling pathway and inducing epithelial-mesenchymal transition

BACKGROUND

N⁶-methyladenosine (m⁶A) modification, as the most abundant RNA modification, widely participates in the physiological process and is involved in multiple disease progression, especially cancer. YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) is a pivotal m⁶A "reader" protein, which has been reported in multiple cancers. However, the role and molecular mechanism of YTHDF1 in HCC are still not fully elucidated.

METHODS

Based on various bioinformatics databases, q-RT PCR, western blot, and a tissue microarray containing 90 HCC samples, we examined the expression of YTHDF1 in HCC. Then, we applied the loss-of-function experiments to explore the role of YTHDF1 in HCC by in vitro and in vivo assays. Finally, we performed the gene set enrichment analysis (GSEA) to predict the potential signaling pathway of YTHDF1 involved in HCC and further verified this prediction.

RESULTS

YTHDF1 was overexpressed in HCC and associated with HCC grade. Depletion of YTHDF1 markedly impaired the proliferation, migration, invasion, and cell cycle process of HCC cells. Mechanistically, YTHDF1 promoted the growth of HCC cells via activating the PI3K/AKT/mTOR signaling pathway. Moreover, we also demonstrated that the epithelial-mesenchymal transition (EMT) mediated the promoting effect of YTHDF1 on the migration and invasion of HCC cells.

CONCLUSIONS

YTHDF1 contributes to the progression of HCC by activating PI3K/AKT/mTOR signaling pathway and inducing EMT.

N6-methyladenosine-dependent signalling in cancer progression and insights into cancer therapies

The N6-methyladenosine (m6A) modification is a dynamic and reversible epigenetic modification, which is co-transcriptionally deposited by a methyltransferase complex, removed by a demethylase, and recognized by reader proteins. Mechanistically, m6A modification regulates the expression levels of mRNA and nocoding RNA by modulating the fate of modified RNA molecules, such as RNA splicing, nuclear transport, translation, and stability. Several studies have shown that m6A modification is dysregulated in the progression of multiple diseases, especially human tumors. We emphasized that the dysregulation of m6A modification affects different signal transduction pathways and involves in the biological processes underlying tumor cell proliferation, apoptosis, invasion and migration, and metabolic reprogramming, and discuss the effects on different cancer treatment.

Novel insights into the m6A-RNA methyltransferase METTL3 in cancer

N6-methyladenosine (m⁶A) is a prevalent internal RNA modification in higher eukaryotic cells. As the pivotal m⁶A regulator, RNA methyltransferase-like 3 (METTL3) is responsible for methyl group transfer in the progression of m⁶A modification. This epigenetic regulation contributes to the structure and functional regulation of RNA and further promotes tumorigenesis and tumor progression. Accumulating evidence has illustrated the pivotal roles of METTL3 in a variety of human cancers. Here, we systemically summarize the interaction between METTL3 and RNAs, and illustrate the multiple functions of METTL3 in human cancer. METLL3 is aberrantly expressed in a variety of tumors. Elevation of METTL3 is usually associated with rapid progression and poor prognosis of tumors. On the other hand, METTL3 may also function as a tumor suppressor in several cancers. Based on the tumor-promoting effect of METTL3, the possibility of applying METTL3 inhibitors is further discussed, which is expected to provide novel insights into antitumor therapy.

Dual effects of N6-methyladenosine on cancer progression and immunotherapy

According to the latest global cancer statistics, cancer has become a major threat to human health, but cancer treatment has encountered many bottlenecks. As an emerging topic in epigenetics, N⁶-methyladenosine (m⁶A) is the most common internal modification on eukaryotic mRNA, which has attracted increasing attention in recent years. Accumulating studies have shown that aberrant m⁶A modifications have profound effects on the characteristics of tumors, which undoubtedly led to a significant breakthrough in cancer treatment. Although m⁶A function as an oncogene or tumor suppressor is not fully revealed, determining its precise function in the development and evolution of malignant tumors is crucial in improving clinical decisions involving targeted therapies. In this review, we briefly introduce the composition of the m⁶A methylation machinery and mainly summarize the biological mechanism of m⁶A in cancer cell death, angiogenesis, epithelial-mesenchymal transition (EMT), and therapeutic resistance. Subsequently, we present the exogenous regulatory factors of m⁶A and highlight the role of m⁶A on immune cells and cancer immunotherapy. The potential therapeutic strategies of m⁶A in human cancer are also discussed, considering research gaps and future applications.

HOXA10 mediates epithelial-mesenchymal transition to promote gastric cancer metastasis partly via modulation of TGFB2/Smad/METTL3 signaling axis

Background

Homeobox A10 (HOXA10) belongs to the HOX gene family, which plays an essential role in embryonic development and tumor progression. We previously demonstrated that HOXA10 was significantly upregulated in gastric cancer (GC) and promoted GC cell proliferation. This study was designed to investigate the role of HOXA10 in GC metastasis and explore the underlying mechanism.

Methods

Immunohistochemistry (IHC) was used to evaluate the expression of HOXA10 in GC. In vitro cell migration and invasion assays as well as in vivo mice metastatic models were utilized to investigate the effects of HOXA10 on GC metastasis. GSEA, western blot, qRT-PCR and confocal immunofluorescence experiments preliminarily analyzed the relationship between HOXA10 and EMT. ChIP-qPCR, dual-luciferase reporter (DLR), co-immunoprecipitation (CoIP), colorimetric m⁶A assay and mice lung metastasis rescue models were performed to explore the mechanism by which HOXA10 accelerated the EMT process in GC.

Results

In this study, we demonstrated HOXA10 was upregulated in GC patients and the difference was even more pronounced in patients with lymph node metastasis (LNM) than without. Functionally, HOXA10 promoted migration and invasion of GC cells in vitro and accelerated lung metastasis in vivo. EMT was an important mechanism responsible for HOXA10-involved metastasis. Mechanistically, we revealed HOXA10 enriched in the TGFB2 promoter region, promoted transcription, increased secretion, thus triggered the activation of TGFβ/Smad signaling with subsequent enhancement of Smad2/3 nuclear expression. Moreover, HOXA10 upregulation elevated m⁶A level and METTL3 expression in GC cells possible by regulating the TGFB2/Smad pathway. CoIP and ChIP-qPCR experiments demonstrated that Smad proteins played an important role in mediating METTL3 expression. Furthermore, we found HOXA10 and METTL3 were clinically relevant, and METTL3 was responsible for the HOXA10-mediated EMT process by performing rescue experiments with western blot and in vivo mice lung metastatic models.

Conclusions

Our findings indicated the essential role of the HOXA10/TGFB2/Smad/METTL3 signaling axis in GC progression and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01859-0.

The m6A methylation landscape stratifies hepatocellular carcinoma into 3 subtypes with distinct metabolic characteristics

Objective

Epigenetic aberration plays an important role in the development and progression of hepatocellular carcinoma (HCC). However, the alteration of RNA N6-methyladenosine (m6A) modifications and its role in HCC progression remain unclear. We therefore aimed to provide evidence using bioinformatics analysis.

Methods

We comprehensively analyzed the m6A regulator modification patterns of 605 HCC samples and correlated them with metabolic alteration characteristics. We elucidated 390 gene-based m6A-related signatures and defined an m6Ascore to quantify m6A modifications. We then assessed their values for predicting prognoses and therapeutic responses in HCC patients.

Results

We identified 3 distinct m6A modification patterns in HCC, and each pattern had distinct metabolic characteristics. The evaluation of m6A modification patterns using m6Ascores could predict the prognoses, tumor stages, and responses to sorafenib treatments of HCC patients. A nomogram based on m6Ascores showed high accuracy in predicting the overall survival of patients. The area under the receiver operating characteristic curve of predictions of 1, 3, and 5-year overall survivals were 0.71, 0.69, and 0.70 in the training cohort, and in the test cohort it was 0.74, 0.75, and 0.71, respectively. M6Acluster C1, which corresponded to hypoactive mRNA methylation, lower expression of m6A regulators, and a lower m6Ascore, was characterized by metabolic hyperactivity, lower tumor stage, better prognosis, and lower response to sorafenib treatment. In contrast, m6Acluster C3 was distinct in its hyperactive mRNA methylations, higher expression of m6A regulators, and higher m6Ascores, and was characterized by hypoactive metabolism, advanced tumor stage, poorer prognosis, and a better response to sorafenib. The m6Acluster, C2, was intermediate between C1 and C3.

Conclusions

HCCs harbored distinct m6A regulator modification patterns that contributed to the metabolic heterogeneity and diversity of HCC. Development of m6A gene signatures and the m6Ascore provides a more comprehensive understanding of m6A modifications in HCC, and helps predict the prognosis and treatment response.