Diagnostic Value of a Group of MicroRNA Genes Hypermethylated in Ovarian Carcinoma

MicroRNA-9 inhibits proliferation and progression in retinoblastoma cells by targeting PTEN

BACKGROUND

Retinoblastoma (RB) is the most prevalent primary intraocular malignancy, which commonly occurs during infant and childhood.

OBJECTIVE

Our study aimed to investigate whether microRNA-9 (miR-9) could regulate RB cells and its mechanism.

METHODS

qRT-PCR analysis was used to detect the expression of miR-9. In addition, to detect the migration of RB cells, wound healing assay was conducted. Xenograft tumor models in nude mice were also established, in order to assess the effects of miR-9 on tumor growth. qRT-PCR, luciferase reporter assay and western blot analysis were used to detect the target of miR-9.

RESULTS

Initially, the expression level of miR-9 was significantly decreased in the RB tissues and blood samples from patients with RB. qRT-PCR, luciferase reporter assay and western blot analysis were used to confirm that PTEN was the target genes of miR-9 and it was negatively regulated by miR-9. When the expression of miR-9 was up-regulated, the cell viability, proliferation, migration and tumor formation were significantly suppressed. Furthermore, the expression level of PTEN was decreased after transfection of miR-9 mimic. Taken together, these results indicated that miR-9 might suppress the cell viability, proliferation, migration and tumor formation in RB by inhibiting PTEN.

CONCLUSION

The in vitro and in vivo experiments demonstrated that miR-9 acts as a tumor suppressor function in RB cells and might serve as novel therapeutic targets for the treatment of RB.

Role of hsa‑miR‑105 during the pathogenesis of paclitaxel resistance and its clinical implication in ovarian cancer

More than 70% of patients with epithelial ovarian cancer (EOC), one of the leading cause of gynecological cancer-related deaths worldwide, are diagnosed at an advanced stage of the disease. Currently, the mainstay for treatment of advanced EOC is tumor debulking surgery followed by combined platinum- and paclitaxel (PTX)-based chemotherapy. However, most patients eventually develop chemoresistance, which remains a major obstacle to successful treatment. Herein, by using clinical specimens and experimentally induced cell models, we found that the expression levels of hsa-miR-105 were significantly decreased in PTX-resistant EOC tissues and cell lines. Follow-up functional experiments demonstrated that repression of hsa-miR-105 conferred resistance to paclitaxel in EOC cells, whereas restoration of hsa-miR-105 expression in situ via intratumoral injection of hsa-miR-105 micrON™ agomir potentiated in vivo sensitivity to PTX and thereafter significantly inhibited tumor growth in a PTX-challenged xenograft model. Mechanistically, hsa-miR-105 exerted its tumor suppressor function by directly inhibiting the zinc and ring finger 2 (ZNRF2) signaling pathway. Importantly, aberrant expression of hsa-miR-105 in both tumor and circulating samples predicted a poor post-chemotherapy prognosis in EOC patients. These findings collectively suggest that hsa-miR-105 may act as a potent tumor suppressor miRNA during the progression of EOC, likely affecting cell proliferation, invasiveness and chemosensitivity to PTX, and functioning at least in part via inhibition of ZNRF2 signaling. The stability and availability and ease in measurement of circulating hsa-miR-105 make it a valuable diagnostic/prognostic biomarker candidate for chemotherapy of EOC.

MicroRNA: A signature for cancer progression

MicroRNAs (miRNAs) are a group of small non-coding RNAs that post-transcriptionally control expression of genes by targeting mRNAs. miRNA alterations partake in the establishment and progression of different types of human cancer. Consequently, expression profiling of miRNA in human cancers has correlations with cancer detection, staging, progression, and response to therapies. Particularly, amplification, deletion, abnormal pattern of epigenetic factors and the transcriptional factors that mediate regulation of primary miRNA frequently change the landscape of miRNA expression in cancer. Indeed, changes in the quantity and quality of miRNAs are associated with the initiation of cancer, its progression and metastasis. Additionally, miRNA profiling has been used to categorize genes that can affect oncogenic pathways in cancer. Here, we discuss several circulating miRNA signatures, their expression profiles in different types of cancer and their impacts on cellular processes.

Prospective pathway signaling and prognostic values of MicroRNA-9 in ovarian cancer based on gene expression omnibus (GEO): a bioinformatics analysis

Objective

MicroRNAs (miRNAs) play a vital role in the development of ovarian cancer (OC). The aim of this study to investigate the prognostic value and potential signaling pathways of hsa-miR-9-5p (miR-9) in OC through literature review and bioinformatics methods.

Methods

The expression of miR-9 in OC was assessed using the public datasets from the Gene Expression Omnibus (GEO) database. And a literature review was also performed to investigate the correlation between miR-9 expression and the OC prognosis. Two mRNA datasets (GSE18520 and GSE36668) of OC tissues and normal ovarian tissues (NOTs) were downloaded from GEO to identify the differentially expressed genes (DEGs). The target genes of hsa-miR-9-5p (TG-miR-9-5p) were predicted using miRWALK3.0 and TargetScan. Then the gene overlaps between DEGs in OC and the predicted TG-miR-9-5p were confirmed using a Venn diagram. After that, overlapping genes were subjected to Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Finally, a protein-protein interaction (PPI) network was constructed using STRING and Cytoscape, and the impact of hub genes on OC prognosis was analyzed.

Results

It was found that OC patients with miR-9 low expression had poor prognosis. A total of 107 DEGs related to both OC and miR-9 were identified. Dozens of DEGs were enriched in developmental process, extracellular matrix structural constituent, cell junction, axon guidance. In the PPI network analysis, 5 of the top 10 hub genes was significantly associated with decreased overall survival of OC patients, namely FBN1 (HR = 1.64, P < 0.05), PRRX1 (HR = 1.76, P < 0.05), SMC2 (HR = 1.22, P < 0.05), SMC4 (HR = 1.31, P < 0.05), and VCAN (HR = 1.48, P < 0.05).

Conclusion

Low expression of miR-9 indicates poor prognosis of OC patients. MiR-9 plays a crucial role in the biological process of OC by binding to target genes, thus affecting the prognosis of patients.

The Role of microRNAs in Epithelial Ovarian Cancer Metastasis

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and the major cause of death is mainly attributed to metastasis. MicroRNAs (miRNAs) are a group of small non-coding RNAs that exert important regulatory functions in many biological processes through their effects on regulating gene expression. In most cases, miRNAs interact with the 3′ UTRs of target mRNAs to induce their degradation and suppress their translation. Aberrant expression of miRNAs has been detected in EOC tumors and/or the biological fluids of EOC patients. Such dysregulation occurs as the result of alterations in DNA copy numbers, epigenetic regulation, and miRNA biogenesis. Many studies have demonstrated that miRNAs can promote or suppress events related to EOC metastasis, such as cell migration, invasion, epithelial-to-mesenchymal transition, and interaction with the tumor microenvironment. In this review, we provide a brief overview of miRNA biogenesis and highlight some key events and regulations related to EOC metastasis. We summarize current knowledge on how miRNAs are dysregulated, focusing on those that have been reported to regulate metastasis. Furthermore, we discuss the role of miRNAs in promoting and inhibiting EOC metastasis. Finally, we point out some limitations of current findings and suggest future research directions in the field.

miR-9-1 gene methylation and DNMT3B (rs2424913) polymorphism may contribute to periodontitis

BACKGROUND

Genetic and epigenetic changes have been associated with periodontitis in various genes; however, little is known about genes involved in epigenetic mechanisms and in oxidative stress.

OBJECTIVE

This study aims to investigate the association of polymorphisms C677T in MTHFR (rs1801133) and -149C→T in DNMT3B (rs2424913), as well as the methylation profiles of MTHFR, miR-9-1, miR-9-3, SOD1, and CAT with periodontitis. The association between polymorphisms and DNA methylation profiles was also analyzed.

METHODOLOGY

The population studied was composed of 100 nonsmokers of both sexes, divided into healthy and periodontitis groups. Genomic DNA was extracted from the epithelial buccal cells, which were collected through a mouthwash. Polymorphism analysis was performed through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while methylation-specific PCR (MSP) or combined bisulfite restriction analysis techniques were applied for methylation analysis.

RESULTS

For DNMT3B, the T allele and the TT genotype were detected more frequently in the periodontitis group, as well as the methylated profile on the miR-9-1 promoter region. There was also a tendency towards promoter region methylation on the CAT sequence of individuals with periodontal disease.

CONCLUSION

The polymorphism -149C→T in DNMT3B (rs2424913) and the methylated profile of the miR-9-1 promoter region are associated with periodontitis.

System of Markers Based on the Methylation of a Group of Proapoptotic Genes in Combination with MicroRNA in the Diagnosis of Breast Cancer

Systems of markers for the diagnosis of breast cancer based on DNA methylation of a group of suppressor protein-coding genes, hypermethylated microRNA genes, and their combinations were compiled. On a representative sample of 70 paired breast cancer specimens (tumor/normal), MS-PCR analysis revealed a significant increase in the methylation frequency of 5 protein-coding genes: RASSF1A suppressor and apoptosis genes APAF1, BAX, BIM/BCL2L11, and DAPK1 (34-61% vs. 4-24%) and 6 microRNA genes: MIRG124G1, MIRG125bG1, MIRG129G2, MIRG148a, MIRG34b/c, and MIRG9G3 (36-76% vs. 6-27%). ROC-analysis showed that a combination of 4 genes (APAF1, BAX, BIM/BCL2L11, and DAPK1) and MIRG125bG1 gene constitute a highly efficient 5-marker system with 100% specificity and sensitivity of 94-96% at AUC=0.98-0.97, suitable also for patients with stage I and II breast cancer. Detection of methylation of at least one gene in this system in biopsy or postoperative material is sufficient to refer the sample to breast cancer.

Marker Systems Based on MicroRNA Gene Methylation for the Diagnosis of Stage I-II Breast Cancer

Groups of microRNA genes, methylation of which is associated with the initial (I-II) stages of breast cancer, are determined, and new markers and marker systems for the disease diagnosis were created on the basis of these data. A total of 14 genes in which methylation was associated with breast cancer were identified with the use of methyl-specific PCR on a representative sample of 70 tumor specimens. Analysis of 46 specimens from patients with clinical stages I and II detected 9 genes (MIR-124-1, MIR-124-3, MIR-125b-1, MIR-129-2, MIR-132, MIR-148a, MIR-193a, MIR-34b/c, and MIR-9-3), in which methylation was associated with the initial stages of the disease. Using ROC analysis, we formed two systems including 6 markers each and detecting breast cancer at stages I-II with high sensitivity (89 and 91%) and specificity (88%) at AUC=0.92-0.93. These sets were validated on the total sample of 70 specimens including all disease stages; they showed 93 and 94% sensitivities, 88% specificity, and AUC=0.95. Highly sensitive systems of markers, based on microRNA gene methylation, were created for the diagnosis of breast cancer at stages I-II.

Epigenetic Biomarkers in the Management of Ovarian Cancer: Current Prospectives

Ovarian cancer (OC) causes significant morbidity and mortality as neither detection nor screening of OC is currently feasible at an early stage. Difficulty to promptly diagnose OC in its early stage remains challenging due to non-specific symptoms in the early-stage of the disease, their presentation at an advanced stage and poor survival. Therefore, improved detection methods are urgently needed. In this article, we summarize the potential clinical utility of epigenetic signatures like DNA methylation, histone modifications, and microRNA dysregulation, which play important role in ovarian carcinogenesis and discuss its application in development of diagnostic, prognostic, and predictive biomarkers. Molecular characterization of epigenetic modification (methylation) in circulating cell free tumor DNA in body fluids offers novel, non-invasive approach for identification of potential promising cancer biomarkers, which can be performed at multiple time points and probably better reflects the prevailing molecular profile of cancer. Current status of epigenetic research in diagnosis of early OC and its management are discussed here with main focus on potential diagnostic biomarkers in tissue and body fluids. Rapid and point of care diagnostic applications of DNA methylation in liquid biopsy has been precluded as a result of cumbersome sample preparation with complicated conventional methods of isolation. New technologies which allow rapid identification of methylation signatures directly from blood will facilitate sample-to answer solutions thereby enabling next-generation point of care molecular diagnostics. To date, not a single epigenetic biomarker which could accurately detect ovarian cancer at an early stage in either tissue or body fluid has been reported. Taken together, the methodological drawbacks, heterogeneity associated with ovarian cancer and non-validation of the clinical utility of reported potential biomarkers in larger ovarian cancer populations has impeded the transition of epigenetic biomarkers from lab to clinical settings. Until addressed, clinical implementation as a diagnostic measure is a far way to go.