Gene Signatures and Prognostic Values of m6A RNA Methylation Regulators in Ovarian Cancer

Research Advances in the Roles of N6-Methyladenosine Modification in Ovarian Cancer

Ovarian cancer (OC) is the most lethal gynecological tumor, characterized by its insidious and frequently recurring metastatic progression. Owing to limited early screening methods, over 70% of OC cases are diagnosed at advanced stages, typically stage III or IV. Recently, N6-methyladenosine (m6A) modification has emerged as a hotspot of epigenetic research, representing a significant endogenous RNA modification in higher eukaryotes. Numerous studies have reported that m6A-related regulatory factors play pivotal roles in tumor development through diverse mechanisms. Moreover, recent studies have indicated the aberrant expression of multiple regulatory factors in OC. Therefore, this paper comprehensively reviews research advancements concerning m6A in OC, aiming to elucidate the regulatory mechanism of m6A-associated regulators on pivotal aspects, such as proliferation, invasion, metastasis, and drug resistance, in OC. Furthermore, it discusses the potential of m6A-associated regulators as early diagnostic markers and therapeutic targets, thus contributing to the diagnosis and treatment of OC.

RNA epigenetic modifications in ovarian cancer: The changes, chances, and challenges

Ovarian cancer (OC) is the most common female cancer worldwide. Patients with OC have high mortality because of its complex and poorly understood pathogenesis. RNA epigenetic modifications, such as m6 A, m1 A, and m5 C, are closely associated with the occurrence and development of OC. RNA modifications can affect the stability of mRNA transcripts, nuclear export of RNAs, translation efficiency, and decoding accuracy. However, there are few overviews that summarize the link between m6 A RNA modification and OC. Here, we discuss the molecular and cellular functions of different RNA modifications and how their regulation contributes to the pathogenesis of OC. By improving our understanding of the role of RNA modifications in the etiology of OC, we provide new perspectives for their use in OC diagnosis and treatment. This article is categorized under: RNA Processing > RNA Editing and Modification RNA in Disease and Development > RNA in Disease.

Modifications of noncoding RNAs in cancer and their therapeutic implications

In the last 50 years, over 150 various chemical modifications on RNA molecules, including mRNAs, rRNAs, tRNAs, and other noncoding RNAs (ncRNAs), have been identified and characterized. These RNA modifications regulate RNA biogenesis and biological functions and are widely involved in various physiological processes and diseases, including cancer. In recent decades, broad interest has arisen in the epigenetic modification of ncRNAs due to the increased knowledge of the critical roles of ncRNAs in cancer. In this review, we summarize the various modifications of ncRNAs and highlight their roles in cancer initiation and progression. In particular, we discuss the potential of RNA modifications as novel biomarkers and therapeutic targets in cancer.

WTAP dysregulation-mediated HMGN3-m6A modification inhibited trophoblast invasion in early-onset preeclampsia

Early-onset preeclampsia (ePE) originates from abnormal implantation and placentation that involves trophoblast invasion, but its pathophysiology is not entirely understood. N6-methyladenosine (m6A) regulators mediate the progression of various cancers. The invasiveness of trophoblast cells is similar to that of tumor cells. However, little is known regarding the potential role of m6A modification in ePE and the underlying mechanism. This study aimed to explore the m6A level in placental tissue samples collected from ePE patients and to investigate whether m6A modification was an essential part of PE pathogenesis. The m6A level in placental tissue samples of 80 PE participants was examined. MeRIP-microarray, RNA-Seq, luciferase reporter assay, and RNA immunoprecipitation chip (RIP) assay were performed. The m6A level in the ePE group was significantly reduced compared with the control group. Wilms' tumor 1-associating protein (WTAP) regulated trophoblast cell migration and invasion. Mechanistically, the high mobility group nucleosomal binding domain 3 (HMGN3) gene was a target gene of WTAP in trophoblast (p < .05). WTAP enhanced the stability of HMGN3 mRNA through binding with its 3'-UTR m6A site(+485A, +522A). HMGN3 was recognized by m6A recognition protein insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), which was inhibited when knocking down WTAP. Both m6A and WTAP levels were downregulated in ePE. The m6A modification mediated by WTAP/IGF2BP1/HMGN3 axis might contribute to abnormal trophoblast invasion. Our work provided a foundation for further exploration of RNA epigenetic regulatory patterns in ePE, and indicated a new treatment strategy for ePE.

Roles of N6-methyladenosine (m6A) modifications in gynecologic cancers: mechanisms and therapeutic targeting

Uterine and ovarian cancers are the most common gynecologic cancers. N6−methyladenosine (m6A), an important internal RNA modification in higher eukaryotes, has recently become a hot topic in epigenetic studies. Numerous studies have revealed that the m6A-related regulatory factors regulate the occurrence and metastasis of tumors and drug resistance through various mechanisms. The m6A-related regulatory factors can also be used as therapeutic targets and biomarkers for the early diagnosis of cancers, including gynecologic cancers. This review discusses the role of m6A in gynecologic cancers and summarizes the recent advancements in m6A modification in gynecologic cancers to improve the understanding of the occurrence, diagnosis, treatment, and prognosis of gynecologic cancers.

Effects of N6-Methyladenosine Modification on Cancer Progression: Molecular Mechanisms and Cancer Therapy

N⁶-methyladenosine (m⁶A) is a major internal epigenetic modification in eukaryotic mRNA, which is dynamic and reversible. m⁶A is regulated by methylases (“writers”) and demethylases (“erasers”) and is recognized and processed by m⁶A-binding proteins (“readers”), which further regulate RNA transport, localization, translation, and degradation. It plays a role in promoting or suppressing tumors and has the potential to become a therapeutic target for malignant tumors. In this review, we focus on the mutual regulation of m⁶A and coding and non-coding RNAs and introduce the molecular mechanism of m⁶A methylation involved in regulation and its role in cancer treatment by taking common female malignant tumors as an example.

A Panel of E2F Target Gene Signature Predicting the Prognosis of Hepatocellular Carcinoma

Hepatocellular carcinoma is one of the most malignant tumors, and the therapeutic effects of traditional treatments are poor. It is urgent to explore and identify new biomarkers and therapeutic targets to develop novel treatments which are individualized and effective. Three hallmarks, including E2F targets, G2M checkpoint and DNA repair, were collected by GSEA analysis. The panel of E2F-related gene signature consisted of five genes: HN1, KIF4A, CDCA3, CDCA8 and SSRP1. They had various mutation rates ranging from 0.8 to 5% in hepatocellular carcinoma, and patients with gene mutation had poorer prognosis. Among these genes, HN1 has the greatest mutation rate, and SSRP1 has the greatest impact on the model with a B (COX) value of 0.8842. Patients with higher expression of these genes had poorer prognosis. Kaplan-Meier curves in stratified survival analysis confirmed that patients with high risk scores had poor prognosis (p < 0.05). The results of univariate and multivariate COX survival analysis showed that risk score was closely related to the overall survival of patients with hepatocellular carcinoma. For clinical validation, we found that all the genes in the model were upregulated in hepatocellular carcinoma tissues compared to normal liver tissues, which was consistent with the previous results we obtained. Our study demonstrated that a panel of E2F target genes signature including five genes could predict the prognosis of hepatocellular carcinoma. This panel gene signature can facilitate the development of individualized and effective treatment for hepatocellular carcinoma.

The emerging roles of the interaction between m6A modification and c-Myc in driving tumorigenesis and development

N6-methyladenosine (m6A) is an extremely common and conservative posttranscriptional modification, that can specifically target and regulate the expression or stability of a series of tumor-related genes, thus playing critical roles in the occurrence and development of tumors. c-Myc is an important tumorigenic transcription factor that promotes tumorigenesis and development by mainly regulating the expression of downstream target genes. Increasing evidence shows that m6A modification, as well as abnormal expression and regulation of c-Myc, is critical molecular mechanisms driving tumorigenesis and development. Although more evidence has been uncovered about the individual roles of m6A modification or c-Myc in tumors, the interaction between m6A modification and c-Myc in tumorigenesis and development has not been systematically summarized. Therefore, this review is focused on the mutual regulation between m6A modification and c-Myc expression and stability as well as its roles in tumorigenesis and development. We also summarized the potential value of the interaction between m6A modification and m6A expression and stability in tumor diagnosis and treatment, which provides a specific reference for revealing the mechanism of tumor occurrence and development as well as clinical diagnosis and treatment.

Emerging Roles of m6A RNA Methylation Regulators in Gynecological Cancer

Gynecological cancers seriously affect the reproductive system of females; diseases include ovarian tumors, uterine tumors, endometrial cancers, cervical cancers, and vulva and vaginal tumors. At present, the diagnosis methods of gynecological cancer are insufficiently sensitive and specific, leading to failure of early disease detection. N⁶-methyladenosine (m⁶A) plays various biological functions in RNA modification and is currently studied extensively. m⁶A modification controls the fate of transcripts and regulates RNA metabolism and biological processes through the interaction of m⁶A methyltransferase (“writer”) and demethylase (“erasers”) and the binding protein decoding m⁶A methylation (“readers”). In the field of epigenetics, m⁶A modification is a dynamic process of reversible regulation of target RNA through its regulatory factors. It plays an important role in many diseases, especially cancer. However, its role in gynecologic cancers has not been fully investigated. Thus, we review the regulatory mechanism, biological functions, and therapeutic prospects of m⁶A RNA methylation regulators in gynecological cancers.

RNA m6A methylation regulators in ovarian cancer

N6-methyladenosine (m6A) is the most abundant RNA modification of mammalian mRNAs and plays a vital role in many diseases, especially tumours. In recent years, m6A has become the topic of intense discussion in epigenetics. M6A modification is dynamically regulated by methyltransferases, demethylases and RNA-binding proteins. Ovarian cancer (OC) is a common but highly fatal malignancy in female. Increasing evidence shows that changes in m6A levels and the dysregulation of m6A regulators are associated with the occurrence, development or prognosis of OC. In this review, the latest studies on m6A and its regulators in OC have been summarized, and we focus on the key role of m6A modification in the development and progression of OC. Additionally, we also discuss the potential use of m6A modification and its regulators in the diagnosis and treatment of OC.

Gene Signatures and Prognostic Values of N6-Methyladenosine Related Genes in Ovarian Cancer

N6-Methyladenosine (m6A) is one of the most prominent modification regulating RNA processing and metabolism. Increasing studies have illuminated the vital role of m6A methylation in carcinogenesis. However, little is known about the interaction between m6A-related genes and survival of ovarian cancer (OC) patients. The purpose of this study was to obtain more reliable m6A-related genes that could be used as prognostic markers of OC using bioinformatics analysis performed on the RNA-seq data of OC. Gene expression datasets of all m6A-related genes as well as corresponding clinical data were obtained from the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA) databases. We detected differential expressed m6A-related candidate genes as well as their relationship and interaction. m6A RNA methylation regulator ALKBH5 and 35 m6A-related genes are dysregulated in OC. A gene set that could be used as a potential independent prognostic risk feature was further screened including NEBL, PDGFRA, WDR91, and ZBTB4. The results of mRNA expression analysis by PCR were consistent with those of bioinformatics analysis. We applied consensus clustering analysis on the expression of the four prognostic genes and obtained four OC subgroups TM1-TM4. There were significant differences in age, stage and grade among the subgroups, and the overall survival (OS) as well as Disease-free survival (DFS) of TM2 group were shorter than those of the other three groups. Further GO and KEGG enrichment analysis indicated that these differential genes were closely related to biological processes and key signaling pathways involved in OC. In summary, our study has indicated that m6A-related genes are key factors in the progression of OC and have potential effects on the prognostic stratification of OC and the development of treatment strategies.

Identification and validation of lncRNAs involved in m6A regulation for patients with ovarian cancer

Background

Both N6-methyladenosine (m6A) modification and lncRNAs play an important role in the carcinogenesis and cancer inhibition of ovarian cancer (OC). However, lncRNAs involved in m6A regulation (LI-m6As) have never been reported in OC. Herein, we aimed to identify and validate a signature based on LI-m6A for OC.

Methods

RNA sequencing profiles with corresponding clinical information associated with OC and 23 m6A regulators were extracted from TCGA. The Pearson correlation coefficient (PCC) between lncRNAs and 23 m6A regulators (|PCC|> 0.4 and p < 0.01) was calculated to identify LI-m6As. The LI-m6As with significant prognostic value were screened based on univariate Cox regression analysis to construct a risk model by LASSO Cox regression. Gene Set Enrichment Analysis (GSEA) was implemented to survey the biological functions of the risk groups. Several clinicopathological characteristics were utilized to evaluate their ability to predict prognosis, and a nomogram was constructed to evaluate the accuracy of survival prediction. Besides, immune microenvironment, checkpoint, and drug sensitivity in the two risk groups were compared using comprehensive algorithms. Finally, real-time qPCR analysis and cell counting kit-8 assays were performed on an alternative lncRNA, CACNA1G-AS1.

Results

The training cohort involving 258 OC patients and the validation cohort involving 111 OC patients were downloaded from TCGA. According to the PCC between the m6A regulators and lncRNAs, 129 LI-m6As were obtained to perform univariate Cox regression analysis and then 10 significant prognostic LI-m6As were identified. A prognostic signature containing four LI-m6As (AC010894.3, ACAP2-IT1, CACNA1G-AS1, and UBA6-AS1) was constructed according to the LASSO Cox regression analysis of the 10 LI-m6As. The prognostic signature was validated to show completely opposite prognostic value in the two risk groups and adverse overall survival (OS) in several clinicopathological characteristics. GSEA indicated that differentially expressed genes in disparate risk groups were enriched in several tumor-related pathways. At the same time, we found significant differences in some immune cells and chemotherapeutic agents between the two groups. An alternative lncRNA, CACNA1G-AS1, was proven to be upregulated in 30 OC specimens and 3 OC cell lines relative to control. Furthermore, knockdown of CACNA1G‐AS1 was proven to restrain the multiplication capacity of OC cells.

Conclusions

Based on the four LI-m6As (AC010894.3, ACAP2-IT1, CACNA1G-AS1, and UBA6-AS1), the risk model we identified can independently predict the OS and therapeutic value of OC. CACNA1G‐AS1 was preliminarily proved to be a malignant lncRNA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02076-7.