Methylation In Ovarian Cancer Research Articles

Current data and future perspectives on DNA methylation in ovarian cancer (Review).

Ovarian cancer (OC) represents the most prevalent malignancy of the female reproductive system. Its distinguishing features include a high aggressiveness, substantial morbidity and mortality, and a lack of apparent symptoms, which collectively pose significant challenges for early detection. Given that aberrant DNA methylation events leading to altered gene expression are characteristic of numerous tumor types, there has been extensive research into epigenetic mechanisms, particularly DNA methylation, in human cancers. In the context of OC, DNA methylation is often associated with the regulation of critical genes, such as BRCA1/2 and Ras‑association domain family 1A. Methylation modifications within the promoter regions of these genes not only contribute to the pathogenesis of OC, but also induce medication resistance and influence the prognosis of patients with OC. As such, a more in‑depth understanding of DNA methylation underpinning carcinogenesis could potentially facilitate the development of more effective therapeutic approaches for this intricate disease. The present review focuses on classical tumor suppressor genes, oncogenes, signaling pathways and associated microRNAs in an aim to elucidate the influence of DNA methylation on the development and progression of OC. The advantages and limitations of employing DNA methylation in the diagnosis, treatment and prevention of OC are also discussed. On the whole, the present literature review indicates that the DNA methylation of specific genes could potentially serve as a prognostic biomarker for OC and a therapeutic target for personalized treatment strategies. Further investigations in this field may yield more efficacious diagnostic and therapeutic alternatives for patients with OC.

Abstract A008: Characterizing the role of somatic and constitutional methylation in ovarian cancer

Abstract A008: Characterizing the role of somatic and constitutional methylation in ovarian cancer

71P Single nucleotide polymorphisms in the folate metabolic pathway genes and global DNA methylation in ovarian cancer

71P Single nucleotide polymorphisms in the folate metabolic pathway genes and global DNA methylation in ovarian cancer

LncRNA CACNA1G-AS1 up-regulates FTH1 to inhibit ferroptosis and promote malignant phenotypes in ovarian cancer cells.

Previous study revealed that ferritin heavy chain-1 (FTH1) could regulate ferritinophagy and affect intracellular Fe2+ content in various tumors, while its N6-methyladenosine (m6A) RNA methylation was closely related the prognosis of ovarian cancer patients. However, little is known about the role of FTH1 m6A methylation in ovarian cancer (OC) and its possible action mechanisms. In this study we constructed FTH1 m6A methylation regulatory pathway (LncRNA CACNA1G-AS1/IGF2BP1) according to related bioinformatics analysis and research, through clinical sample detections we found that these pathway regulatory factors were significantly up-regulated in ovarian cancer tissues, and their expression levels were closely related to the malignant phenotype of ovarian cancer. In vitro cell experiments showed that LncRNA CACNA1G-AS1 could up-regulate FTH1 expression through IGF2BP1 axis, thus inhibited ferroptosis by regulating ferritinophagy, and finally promoted proliferation and migration in ovarian cancer cells. Tumor-bearing mice studies showed that the knock-down of LncRNA CACNA1G-AS1 could inhibited the tumorigenesis of ovarian cancer cells in vivo condition. Our results demonstrated that LncRNA CACNA1G-AS1 could promote the malignant phenotypes of ovarian cancer cells through FTH1-IGF2BP1 regulated ferroptosis.

Integration of Transcriptome and Epigenome to Identify and Develop Prognostic Markers for Ovarian Cancer.

DNA methylation is a widely researched epigenetic modification. It is associated with the occurrence and development of cancer and has helped evaluate patients' prognoses. However, most existing DNA methylation prognosis models have not simultaneously considered the changes of the downstream transcriptome. Methods. The RNA-Sequencing data and DNA methylation omics data of ovarian cancer patients were downloaded from The Cancer Genome Atlas (TCGA) database. The Consensus Cluster Plus algorithm was used to construct the methylated molecular subtypes of the ovary. Lasso regression was employed to build a multi-gene signature. An independent data set was applied to verify the prognostic value of the signature. The Gene Set Variation Analysis (GSVA) was used to carry out the enrichment analysis of the pathways linked to the gene signature. The IMvigor 210 cohort was used to explore the predictive efficacy of the gene signature for immunotherapy response. Results. We distinguished ovarian cancer samples into two subtypes with different prognosis, based on the omics data of DNA methylation. Differentially expressed genes and enrichment analysis among subtypes indicated that DNA methylation was related to fatty acid metabolism and the extracellular matrix (ECM)-receptor. Furthermore, we constructed an 8-gene signature, which proved to be efficient and stable in predicting prognostics in ovarian cancer patients with different data sets and distinctive pathological characteristics. Finally, the 8-gene signature could predict patients' responses to immunotherapy. The polymerase chain reaction experiment was further used to verify the expression of 8 genes. Conclusion. We analyzed the prognostic value of the related genes of methylation in ovarian cancer. The 8-gene signature predicted the prognosis and immunotherapy response of ovarian cancer patients well and is expected to be valuable in clinical application.

Identifying BRCA wild-type ovarian cancers with a homologous recombination deficiency phenotype (101)

<b>Objectives:</b> It is unknown how best to evaluate <i>BRCA</i> wild-type ovarian carcinomas for homologous recombination deficiency (HRD), and previous studies did not show a survival advantage for <i>BRCA1</i> methylation. We sought to further characterize <i>BRCA1/RAD51C</i> promoter methylation in ovarian cancer (OC). We hypothesized that a combined assay with quantitative methylation and mutation assessment would identify <i>BRCA</i> wild-type ovarian carcinomas with an HRD phenotype. <b>Methods:</b> Digital droplet PCR primers and probes were designed to target CpG sites in the promoter regions of <i>BRCA1</i> and <i>RAD51C</i> known to be associated with transcriptional repression. Multiple aspects of the assay were tested and optimized in a CLIA environment. The fraction of methylated alleles was corrected for neoplastic cellularity and ≥60% was considered highly methylated. The methylated ddPCR (MddPCR) assay was then applied to DNA from banked epithelial ovarian cancer specimens previously assessed by methylation-sensitive PCR (MSP) and BROCA next-generation sequencing. RNA expression of a subset of <i>BRCA1</i> methylated samples was determined using RNA-seq, and expression was compared with methylation using LOESS regression. Clinical characteristics were then compared between highly methylated and unmethylated samples using a t-test for continuous variables, Fisher's exact test for categorical variables, and the log-rank test for overall survival (OS). Additional cases with germline/somatic mutations in homologous recombination repair (HRR) genes identified by BROCA sequencing were included in an overall survival analysis using the log-rank test. <b>Results:</b> Total 370 epithelial OC specimens were tested by MddPCR. MddPCR had 100% concordance with MSP. Among the samples, 9.5% were positive for <i>BRCA1</i> promoter methylation, and 3% were positive for <i>RAD51C</i> promoter methylation ≥5%. RNA expression analysis of a sub-set of <i>BRCA1</i> methylated samples demonstrated that the degree of <i>BRCA1</i> methylation was negatively correlated with <i>BRCA1</i> expression levels (r=-0.82, p<0.001). There were 26 highly methylated neoplastic <i>BRCA1</i> or <i>RAD51C</i> samples, 14 samples with low methylation (5-59% methylated alleles), and 294 samples with no methylation or HRR mutation. The median overall survival was 76 months for highly methylated cases compared to 50 months for unmethylated cases (HR: 0.66, p=0.20). Highly methylated samples were significantly less likely to have had prior chemotherapy exposure (12% vs 31%, <i>p</i>=0.04). Paired primary/recurrent samples were evaluated, two of which contained a highly methylated initial sample and showed a decrease in methylation at the time of recurrence. In the expanded cohort including HRR mutated OC, median OS was 80 months in cases with either high methylation or a non-<i>BRCA</i> HRR mutation compared to 50 months in unmethylated wild-type samples (HR: 0.63, p=0.02), with a survival curve similar to <i>BRCA</i> mutated samples (median OS: 66 months, HR: 0.76, p=0.01). <b>Conclusions:</b> Ovarian cancer that was either highly methylated or had a non-<i>BRCA</i> HRR mutation was associated with increased OS compared to unmethylated/wild-type cases, suggesting an HRD phenotype. Methylated samples had similar OS to HRR mutated cancers; however, survival analysis was limited by the low total number of highly methylated samples. Exposure to chemotherapy may decrease promoter methylation, and analysis of additional paired samples is ongoing. Quantitative methylation analysis could augment tumor sequencing in identifying OC with a favorable response to PARP inhibitors.Fig. 1

Decreased EMILIN2 correlates to metabolism phenotype and poor prognosis of ovarian cancer.

This study aimed to explore the function and related mechanisms of elastin microfibril interfacer 2 (EMILIN2) in ovarian cancer. First, the expression level of EMILIN2 was detected in patient tissues and its correlation with overall survival rate was analysed. Then, EMILIN2 was overexpressed in ovarian cancer cell lines to observe its function and effect on Warburg effect. By detecting its promoter region methylation, the epigenetic regulatory role was explored. Finally, through the luciferase reporter assay and siRNA tools, the regulatory mechanism of p53 on EMILIN2 was investigated. It was detected in clinical samples that down-regulated EMILIN2 was associated with poor prognosis of ovarian cancer. It was further found that EMILIN2 regulated the metabolic phenotype of ovarian cancer cells. The expression of EMILIN2 was epigenetically regulated by its promoter methylation. Also, it was found that p53 regulated the expression of EMILIN2 and the p53/EMILIN2 axis regulated the Warburg effect in ovarian cancer cells. EMILIN2 was inhibited by methylation in ovarian cancer. In summary, p53 can promote and regulate its transcription by binding to the promoter region of EMILIN2, thereby affecting the Warburg effect and inhibiting tumours. Therefore, EMILIN2 might be a potential target for clinical diagnosis and treatment of ovarian cancer.

Sesquiterpene Lactones Modulated DNA Methylation through Inhibition of DNMTs in Ovarian Cancer Cells

Inappropriate DNA methylation of tumour suppressor genes can affect their expression and function, and as such, DNA methylation has been a promising target for anti-cancer therapy. In gynaecological malignancy, ovarian cancer has the highest associated rate of mortality. This study investigated the in vitro cytotoxicity of four sesquiterpene lactones (SLs), including dehydroleucodine (Deh), alantolactone (Ala), costunolide (Cos), and parthenolide (Pat), and their effect on DNA methylation in ovarian cancer. The binding of the SLs with DNA methyltransferases (DNMTs) were studied using molecular docking. The in vitro antiproliferative activity was evaluated in human ovarian cancer cell lines. SL-induced pro-apoptotic activity and effect on cell cycles was evaluated using enzymatic assays and flow cytometry. Global DNA methylation and DNMTs activity by SLs were measured using ELISA assays. DNA methylation and expression of tumour suppressor genes MHL1 and PTEN were quantified using pyrosequencing and RT-qPCR, respectively. SLs displayed strong binding to DNMT1, 3A and 3B in silico, with Deh exhibiting the strongest binding. SLs showed cytotoxicity in the order of Deh ≈ Ala > Pat > Cos, induced apoptosis, and arrested cell cycle at G2/M phase. Deh and Ala possessed DNMT inhibitory activity, reduced global and gene-specific DNA methylation, and increased expression of notable MHL1 and PTEN, which could contribute to the induction of apoptosis and cell death. In conclusion, Deh and Ala, possess strong cytotoxicity and hold the exciting potential as novel therapeutic agents in ovarian cancer.

Leptin Protein Expression and Promoter Methylation in Ovarian Cancer: A Strong Prognostic Value with Theranostic Promises.

Ovarian cancer (OC) is the deadliest among all gynecological cancers. Epidemiological studies showed that obesity might influence many cancers including OC. One of the key factors that may link obesity and OC is leptin (LEP), known as an adipokine with pleiotropic effects on body homeostasis. This study aims to investigate the expression pattern of LEP, assess the methylation profiles of LEP and their associations with clinicopathological features including survival outcomes of OC patients. The protein expression of LEP was evaluated in 208 samples using both tissue microarray and immunohistochemistry techniques. The methylation profiles of LEP were measured in 63 formalin-fixed, paraffin-embedded tumor tissues by quantitative polymerase chain reaction using a MethyLight assay. Our results showed a significant association of LEP protein overexpression with several clinicopathological variables, mainly tumor subtype, LVI, age of menarche, tumor size and stage (p < 0.04). Kaplan–Meier analysis (using low expression versus high expression as a discriminator) indicated that LEP protein overexpression is a powerful positive prognosticator of both OC recurrence (DFS) and disease-specific survival (DSS) in our OC cohort (log-rank p = 0.01 and p = 0.002, respectively). This implies that patients with high LEP expression profiles live longer with less recurrence rates. Methylation analysis results demonstrated a clear association between no/low LEP protein expression pattern (38%) and LEP promoter CpG island hypermethylation (43%). Results of this study suggest that LEP is a powerful prognosticator of OC recurrence and DSS. LEP expression in OC seems to be regulated by its promoter hypermethylation through gene partial/total silencing. Further multi-institutional studies using larger cohorts are required to demystify the intricate molecular functions of this leptin-driven effects in OC pathophysiology and to accurately assess its theranostic potential and validate its prognostic/predictive power in OC onset, progression towards more effective and personalized management of OC patients.

Multiomics analysis identifies key genes and pathways related to N6-methyladenosine RNA modification in ovarian cancer.

Aims: To explore the pathways and target genes related to N6-methyladenosine (m6A) methylation in ovarian cancer and their effect on patient prognosis. Methods & materials: The Cancer Genome Atlas was used to screen genes related to m6A regulators in terms of gene expression, mutationand copy number variation. These genes were subjected to pathway enrichment analysis. Prognosis-related genes were screened and involved in risk signature construction. Immunohistochemistry was used for verification. Results: We obtained 1408 genes dysregulated in parallel to m6A regulators, which were mainly involved in theplatelet activation pathway. The m6A-related signature was constructed based on the expression of fourprognosis-related genes (RPS6KA2, JUNB, HNF4Aand P2RX1). Conclusion: This work provides new insights into the mechanism of m6A methylation in ovarian cancer.

The Role Caspase-8 and DNA Methylation in patients with Ovarian Cancer: Relationship with Oxidative Stress and Inflammation

Background: Ovarian cancer (OC) is the most common cancer and a leading cause of death in women. It well known that suppress the apoptosis initiates tumor and its development. Oxidative stress, and inflammation showed to have a role in tumorigenesis. However, the mechanism still unclear. Methods: 90 females were involved in the current study. Blood samples were obtained from thirty healthy controls, thirty premenopausal women, and thirty postmenopausal women with primary diagnosis of ovarian cancer. Plasma SOD activity was determined by spectrophotometry method, plasma levels of 8-OHG, IL-8, and Cas-8 were measured by ELISA. methylation specific PCR (MSP PCR) was applied for measurements of un-methylation and methylation levels of Cas-8 gene. Result: The results showed a significant decrease in SOD activity in postmenopausal group compared to premenopausal women and control groups (P &lt; 0.05). A significant increase in 8-OHG and IL-8 levels in both OC groups compared with control group (P &lt; 0.05). Apoptosis were decreased through levels of Cas-8 in patients group compared to control group (P&lt; 0.05). Also a high level methylation of Cas-8 gene was observed in plasma sample of patient groups compared to control group. Conclusions: low levels of Cas-8 and methylation of Cas-8 may be involved in OC carcinogenesis and consider as diagnostic marker. Oxidative stress-mediated inflammatory response and methylation of Cas-8, this may be for promoter hyper methylation in OC. Taken together, the result open new sight in strategy therapy for OC.

LAMA3 DNA methylation and transcriptome changes associated with chemotherapy resistance in ovarian cancer

ObjectiveLAMA3 is a widely studied methylated gene in multiple tumors, but the relationship between chemotherapy resistance in ovarian cancer is unclear. In this study, LAMA3 methylation was predicted by bioinformatics, and the ability of LAMA3 methylation to predict the chemotherapy resistance and prognosis of ovarian cancer was confirmed in experiments.MethodsMultiple databases have performed the bioinformatics analysis of methylation and transcription factor binding site (TFBS) on the promoter region of LAMA3 gene. Pyrosequencing detected the methylation of LAMA3. QRT-PCR and immunohistochemistry detected the expression of LAMA3. Real Time Cell Analyzer (RTCA) detects changes in cell proliferation, migration and invasion ability. Flow cytometry was used to detect apoptosis.ResultsCPG islands of 176 bp, 134 bp, 125 bp and 531 bp were predicted in the promoter region of LAMA3 gene. The 4 prediction results are basically overlapped. 7 transcription factor binding sites were predicted, and the one with the highest score was on the predicted CpG island located in the proximal promoter region. LAMA3 hypermethylation and low expression are both associated with chemotherapy resistance and poor prognosis in ovarian cancer. LAMA3 methylation was negatively correlated with expression. After upregulation of LAMA3, the proliferation ability of chemoresistant ovarian cancer cell decreased, while the ability of apoptosis, invasion and migration increased.ConclusionLAMA3 hypermethylation is associated with chemotherapy resistance and poor prognosis. As a typical CpG island gene, LAMA3(cg20937934) and LAMA3(cg13270625) hypermethylation is negatively correlated with low expression. LAMA3 promotes the invasion, migration and apoptosis of SKOV3DDP. In the future, the mechanism of LAMA3 methylation in ovarian cancer will need to be further studied.

Novel miRNAs as Potential Regulators of PD-1/PD-L1 Immune Checkpoint, and Prognostic Value of MIR9-1 and MIR124-2 Methylation in Ovarian Cancer

Novel miRNAs as Potential Regulators of PD-1/PD-L1 Immune Checkpoint, and Prognostic Value of MIR9-1 and MIR124-2 Methylation in Ovarian Cancer

Abstract 130: CpG binding protein promotes cell proliferation through H3K4 methylation in ovarian cancer

Abstract E3 ubiquitin ligase CRL4 complex activation requires cullin neddylation. MLN4924, a NEDD8-activating enzyme (NAE) inhibitor, reportedly blocked cullin neddylation and inactivated cullin (CUL)-RING E3 ligases (CRLs). Studies have shown that MLN4924 inhibits cell proliferation and survival. We examined the oncostatic and cytotoxic properties of MLN4924 in ovarian cancer. MLN4924 blocked human cancer cell proliferation in nude mice by inhibiting CpG binding protein CFP1 expression. Loss of CFP1 reduced cell growth, promoted apoptosis, and increased senescence. CFP1-dependent H3K4 trimethylation is necessary to maintain the expression of target genes in ovarian cancer cells. We identified bone marrow stromal cell antigen 2 (BST2) and noggin (NOG) as direct targets of CFP1. Their expression was selectively induced by CFP1 deletion. Furthermore, deletion of NOG and overexpression of BST2 prevented the growth-inhibitory effect of CFP1 loss. Our study further demonstrated that CRL4 inactivation reduced CFP1 transcription and trimethylation on lysine 4 of histone H3, which in turn inhibited cell proliferation and induced apoptosis. Therefore, CRL4 constitutes a druggable target in ovarian cancer. Citation Format: Liu-qing Yang, Han-yin Hu, Yao Han, Heng-Yan Zhu, Xiao-min Wang, Lei Ao, Ying Xu, Xuan Huang, Xuan Che, Li-Zhong Wang, Ya-Bo Jiang, Chun-wei Xu, Shu-Qun Cheng, Michal Heger, Wei-wei Pan. CpG binding protein promotes cell proliferation through H3K4 methylation in ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 130.

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

Background:N6-methyladenosine (m6A) is the most common form of mRNA modification under the field of “RNA epigenetics.” However, its role in ovarian cancer (OC) development is poorly understood. In the current study, we aimed to identify gene signatures and prognostic values of m6A RNA methylation regulators.Method:Specifically, we downloaded Mutations and Copy number variant (CNV) data from the TCGA database for 579 OC patients, then analyzed gene expression and prognosis value using integrative bioinformatics. Thereafter, we verified the related biological processes of Wilms’ tumor 1-associating protein (WTAP) gene using Gene set enrichment analysis (GSEA).Results:Results showed that almost all ovarian cancer patients (99.31%) have CNVs with at least 1 m6A regulatory gene, whereas 83.76% of cases exhibited concurrence of CNVs in more than 4 m6A regulatory genes. Additionally, alteration of m6A regulators was associated with historical grade, whereas integrative bioinformatics and Cox multivariate model analysis revealed a significant correlation between high WTAP expression and worse ovarian cancer outcomes. Moreover, GSEA revealed that high WTAP expression was associated with cell cycle regulation and MYC targets.Conclusion:Overall, our findings demonstrate the significance of high-frequency genetic alterations of m6A RNA methylation regulators and WTAP’s poor prognosis value in OC. These findings provide valuable insights into the role of m6A methylation in OC, and will be vital in guiding development of novel treatment therapies.

PRMT1 Is Recruited via DNA-PK to Chromatin Where It Sustains the Senescence-Associated Secretory Phenotype in Response to Cisplatin

Protein arginine methyltransferase 1 (PRMT1) is overexpressed in various human cancers and linked to poor response to chemotherapy. Various PRMT1 inhibitors are currently under development; yet, we do not fully understand the mechanisms underpinning PRMT1 involvement in tumorigenesis and chemoresistance. Using mass spectrometry-based proteomics, we identified PRMT1 as regulator of arginine methylation in ovarian cancer cellstreated with cisplatin. We showed that DNA-dependent protein kinase (DNA-PK) binds to and phosphorylates PRMT1 in response to cisplatin, inducing its chromatin recruitment and redirecting its enzymatic activity toward Arg3 of histone H4 (H4R3). On chromatin, the DNA-PK/PRMT1 axis induces senescence-associated secretory phenotype through H4R3me2a deposition at pro-inflammatory gene promoters. Finally, PRMT1 inhibition reduces the clonogenic growth of cancer cells exposed to low doses of cisplatin, sensitizing them to apoptosis. While unravelling the role of PRMT1 in response to genotoxic agents, our findings indicate the possibility of targeting PRMT1 to overcome chemoresistance in cancer.

Novel miRNAs as Potential Regulators of PD-1/PD-L1 Immune Checkpoint, and Prognostic Value of MIR9-1 and MIR124-2 Methylation in Ovarian Cancer

Ovarian cancer (OC) is mostly detected at late stages weighed down with metastasis, and the five-year survival rate of patients is only 30%, which dictates the necessity to develop gentler and more selectively targeted drugs that current chemotherapeutic agents. The search for factors that can influence on the activity of the PD-1/PD-L1 immune checkpoint signaling pathway in tumors is relevant, and micro RNAs (miRNAs) play an important role in it. Over the past 5 years, only a few miRNAs (miR-34a, miR-145, and miR-424), which have a regulatory effect on the PD-1/PD-L1 system in OC patients, have been discovered. In present work, the methylation levels of 13 miRNA genes in 26 primary tumors and 19 peritoneal metastases of OC patients were determined and compared with the level of the soluble form of PD-L1 (sPD-L1) in the blood plasma of the same patients. It was shown that the methylation levels of five miRNA genes (MIR124-2, MIR34B/C, MIR9-1, MIR9-3, and MIR339) in tumors are in direct correlation with the sPD-L1 level in the blood plasma. In addition, when analyzing these five genes, a significant association of the methylation level of the MIR9-1 gene with a decrease in the three-year relapse-free survival, and a trend for decrease in the three-year survival rate with the methylation level of the MIR124-2 gene of OC patients were determined. Thus, the first data suggesting the role of inhibitors of the sPD-L1 immune checkpoint for five miRNAs (miR-124, miR-34b, miR-34c, miR-9, miR-339) and the possibility of using hypermethylated MIR9-1 and, presumably, MIR124-2 genes as independent prognostic markers of poor disease-free survival in OC patients were obtained.

Clinical and prognostic effects of CDKN2A, CDKN2B and CDH13 promoter methylation in ovarian cancer: a study using meta-analysis and TCGA data

Background: Promoter methylation of tumour suppressor genes (TSGs) CDKN2A, CDKN2B and CDH13 has been reported in ovarian cancer. However, the clinicopathological characteristics and prognostic role of CDKN2A, CDKN2B and CDH13 promoter methylation in ovarian carcinoma remained unclear.Methods: The pooled odds ratio (OR) or hazard ratios (HRs) with their 95% confidence intervals (95% CIs) were calculated in this meta-analysis. The Cancer Genome Atlas data were obtained to confirm the role of CDKN2A, CDKN2B and CDH13 methylation in ovarian cancer.Results: CDKN2A, CDKN2B and CDH13 promoter methylation was higher in ovarian cancer than in normal ovarian tissues. CDH13 promoter methylation was correlated with tumour histology (serous vs. non-serous type: OR = 0.33, p = 0.031). CDKN2A promoter methylation was not linked to overall survival (OS), but it was correlated with a poor prognosis in progression-free survival (HR = 1.55, p = 0.004). TCGA data showed no correlation between CDKN2A, CDKN2B and CDH13 methylation and OS as well as disease-free survival (DFS).Conclusions: CDKN2A, CDKN2B and CDH13 promoter methylation may correlate with the increased risk of ovarian cancer. CDKN2A promoter methylation may be an independent prognostic biomarker for predicting progression-free survival.

Importance of Cadherins Methylation in Ovarian Cancer: a Next Generation Sequencing Approach.

Epigenetic aberrations are well known to play an important role in carcinogenesis, and also have a great potential to serve as biomarkers in many types of cancers, including ovarian cancer in which sensitive and specific biomarkers and detection methods are critically needed. The aim of this study was to investigate methylation of cadherin genes CDH10, CDH13 and CDH18 in ovarian cancer tissue by comparison with control tissue. The study group consisted of 38 patients with ovarian cancer and 25 control patients. For detection of epigenetic events we used next generation sequencing, the most important data were confirmed using high-resolution melting analysis and real-time PCR. We observed significantly higher methylation in CDH13, sporadic methylation in CDH10 and loss of methylation in CDH18 in the ovarian cancer group compared with the control group. These observations suggest that changes in methylation of cadherin genes may be one of the major mechanisms associated with ovarian cancer progression. In addition, because of the high frequency of methylation of the CDH13 gene in the early stages of ovarian cancer, the analyzed CpG sites might be good targets for next study of potential ovarian cancer screening biomarkers.

Quantitative assessment of aberrant P16INK4a methylation in ovarian cancer: a meta-analysis based on literature and TCGA datasets.

Epigenetic alteration of P16INK4a is conventionally thought to induce the initiation of carcinoma. However, the role of P16INK4a methylation in ovarian cancer still remains controversial. Therefore, we performed a meta-analysis to further elucidate the relationship between P16INK4a promoter methylation and ovarian cancer. A total of 24 studies, including 20 on risk, 10 on clinicopathological features, and 3 on prognosis, were included in our meta-analysis. Our results indicated that the frequency of P16INK4a methylation in cancer tissues was significantly higher than normal tissues and low malignant potential tumor tissues (odds ratio [OR] =5.01, 95% CI=1.55–16.14; OR =1.88, 95% CI=1.10–3.19, respectively), but similar to benign tissues (OR =1.18, 95% CI=0.52–2.65). Furthermore, P16INK4a promoter methylation was not strongly correlated with age, clinical stage, tumor differentiation, or histological subtype in patients with ovarian cancer. Additionally, survival analysis showed that patients with P16INK4a promoter methylation had a shorter progression-free survival in univariate and multivariate Cox regression models (hazard ratio =1.68, 95% CI=1.26–2.24; hazard ratio =1.55, 95% CI=1.15–2.08; respectively). In The Cancer Genome Atlas datasets, the methylation levels of seven out of nine CpG sites were significantly increased in the ovarian tumor tissues compared with the normal tissues. In conclusion, the present meta-analysis suggests that P16INK4a promoter methylation may be useful in distinguishing malignant cancer from healthy ovarian tissues, and it may be a potential predictive marker for prognosis in patients with ovarian cancer.