Analysis of Promoter Methylation in Breast Cancer
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ABSTRACT:
ORGANISM(S): Homo sapiens
SUBMITTER: Sproul D
PROVIDER: S-ECPF-GEOD-26990 | biostudies-other | 2011 Mar
REPOSITORIES: biostudies-other
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Project description:Promoter methylation was assayed in a number of breast cancer and control normal samples along with the effects of 5'-aza-2'-deoxycytidine on breast cancer cell line transcriptomes. Aberrant promoter hypermethylation is frequently observed in cancer. The potential for this to contribute to tumour development depends on whether the genes affected are repressed because of their methylation. Many aberrantly methylated genes play important roles in development and are bivalently marked in ES cells suggesting that their aberrant methylation may reflect developmental processes. We investigated this possibility by analysing promoter methylation in 19 breast cancer cell lines, 10 normal tissues and 47 primary breast tumours. In order to determine the role of DNA methylation in silencing genes in breast cancer, we also examined the effects of the demethylating agent 5-aza-2?-deoxycytidine on gene expression in 3 breast cancer cell lines and HCT116 cells. Gene expression changes were also assayed in the DNA methyltransferase deficient HCT116 DKO cell line. Our findings implicate aberrant DNA methylation as a marker of cell lineage rather than tumour progression and suggest that, in most cases, it does not cause the repression with which it is associated. A number of human breast cancer cell lines, breast tumours and normal tissues were analysed on Illumina Infinium Methylation27 Beadchips to assay promoter methylation. Selected cell lines were analysed on expression arrays before and after treatment with 5-aza-2'-deoxycytidine.
2011-03-07 | E-GEOD-26990 | biostudies-arrayexpress
Project description:Promoter methylation was assayed in a number of breast cancer and control normal samples along with the effects of 5'-aza-2'-deoxycytidine on breast cancer cell line transcriptomes. Aberrant promoter hypermethylation is frequently observed in cancer. The potential for this to contribute to tumour development depends on whether the genes affected are repressed because of their methylation. Many aberrantly methylated genes play important roles in development and are bivalently marked in ES cells suggesting that their aberrant methylation may reflect developmental processes. We investigated this possibility by analysing promoter methylation in 19 breast cancer cell lines, 10 normal tissues and 47 primary breast tumours. In order to determine the role of DNA methylation in silencing genes in breast cancer, we also examined the effects of the demethylating agent 5-aza-2?-deoxycytidine on gene expression in 3 breast cancer cell lines and HCT116 cells. Gene expression changes were also assayed in the DNA methyltransferase deficient HCT116 DKO cell line. Our findings implicate aberrant DNA methylation as a marker of cell lineage rather than tumour progression and suggest that, in most cases, it does not cause the repression with which it is associated.
2011-03-07 | GSE26990 | GEO
Project description:BackgroundBreast cancer is one of the most common malignancies among women. Recent studies revealed that differentially methylated regions (DMRs) are implicated in regulating gene expression. The goal of this research was to determine which genes and pathways are dysregulated in breast cancer when their promoters are methylated in an abnormal way, leading to differential expression. Whole-genome bisulfite sequencing was applied to analyze DMRs for eight peripheral blood samples collected from five Saudi females diagnosed with stages I and II of breast cancer aligned with three normal females. Three of those patients and three normal samples were used to determine differentially expressed genes (DEG) using Illumina platform NovaSeq PE150.ResultsBased on ontology (GO) and KEGG pathways, the analysis indicated that DMGs and DEG are closely related to associated processes, such as ubiquitin-protein transferase activity, ubiquitin-mediated proteolysis, and oxidative phosphorylation. The findings indicated a potentially significant association between global hypomethylation and breast cancer in Saudi patients. Our results revealed 81 differentially promoter-methylated and expressed genes. The most significant differentially methylated and expressed genes found in gene ontology (GO) are pumilio RNA binding family member 1 (PUM1) and zinc finger AN1-type containing 2B (ZFAND2B) also known as (AIRAPL).ConclusionThe essential outcomes of this study suggested that aberrant hypermethylation at crucial genes that have significant parts in the molecular pathways of breast cancer could be used as a potential prognostic biomarker for breast cancer.
| S-EPMC10332364 | biostudies-literature
Project description:Telomeres at the ends of eukaryotic chromosomes play a critical role in tumorgenesis. Using microfluidic PCR and next-generation bisulfite sequencing technology, we investigated the promoter methylation of 29 telomere related genes in paired tumor and normal tissues from 184 breast cancer patients. The expression of significantly differentially methylated genes was quantified using qPCR method.We observed that the average methylation level of the 29 telomere related genes was significant higher in tumor than that in normal tissues (P = 4.30E-21). A total of 4 genes (RAD50, RTEL, TERC and TRF1) showed significant hyper-methylation in breast tumor tissues. RAD51D showed significant methylation difference among the four breast cancer subtypes. The methylation of TERC showed significant association with ER status of breast cancer. The expression profiles of the 4 hyper-methylated genes showed significantly reduced expression in tumor tissues. The integration analysis of methylation and expression of these 4 genes showed a good performance in breast cancer prediction (AUC = 0.947).Our results revealed the methylation pattern of telomere related genes in breast cancer and suggested a novel 4-gene panel might be a valuable biomarker for breast cancer diagnosis.
| S-EPMC5421942 | biostudies-literature
Project description:ER? and PR levels are critical determinants for breast cancer prognosis and response to endocrine therapy. Although PR is known to be silenced by methylation of its promoter, few studies have correlated methylation with PR levels and outcome in breast cancer. There is only one previous small study comparing methylation of the two PR isoforms, PRA and PRB, which are expressed from different promoters, and finally, there is no prior knowledge of associations between isoform-specific methylation and outcome.We conducted a cohort-based study to test for associations between PRA and PRB methylation, expression, and clinical outcome in tamoxifen-treated patients (n = 500), and in patients who underwent surgery only (n = 500). Methylation and PR levels were measured by bisulfite pyrosequencing and ligand-binding assay, respectively.Low PR levels were significantly associated with worse outcome in all patients. PRA and PRB promoters were methylated in 9.6% and 14.1% of the breast tumors, respectively. The majority (74%) of PR-negative tumors were not methylated despite the significant inverse correlation of methylation and PR levels. PRA methylation was significantly associated with PRB methylation, although a subset of tumors had PRA only (3.9%) or PRB only (8.3%) methylated. Methylation of PRA, but not PRB was significantly associated with worse outcome in the tamoxifen-treated group.Mechanisms other than promoter methylation may be more dominant for loss of PR. Isoform-specific methylation events suggest independent regulation of PRA and PRB. Finally, this article shows for the first time that PRA methylation plays a unique role in tamoxifen-resistant breast cancer.
| S-EPMC3955277 | biostudies-literature
Project description:Recent microarray profiling studies on breast cancer have identified distinct subtypes that are associated with different clinical outcomes. Promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of breast cancer. We proposed that immunohistopathologic subtypes of breast cancer are likely to contain distinct promoter methylation patterns. A panel of 10 gene promoters was assessed by quantitative multiplex methylation-specific PCR in 114 invasive ductal carcinomas from Korea representing the three major subtypes [57 luminal, 24 human epidermal growth factor 2 (HER2), and 33 basal-like] based on immunohistochemical findings of estrogen receptor, progesterone receptor, HER2, cytokeratin 5/6 and epidermal growth factor receptor. The median methylation levels of HIN1, RASSF1A and TWIST, and the average methylation ratio were significantly lower in basal-like subtype compared to luminal or HER2 subtypes. In contrast, BRCA1 methylation level was significantly higher in basal-like subtype than in luminal subtype. The methylation status of a panel of four genes (APC1, CDH, BRCA1 and RAR-β) in luminal and HER2 subtypes were dissimilar, where HER2 tumors showed a significantly higher level of methylation compared to luminal tumors. These results suggest that gene methylation in breast cancer can potentially serve as epigenetic biomarkers and may contribute further to current breast cancer classification.
| S-EPMC3094906 | biostudies-literature
Project description:BackgroundAfrican American (AA) women are diagnosed with more advanced breast cancers and have worse survival than white women, but a comprehensive understanding of the basis for this disparity remains unclear. Analysis of DNA methylation, an epigenetic mechanism that can regulate gene expression, could help to explain racial differences in breast tumor clinical biology and outcomes.MethodsDNA methylation was evaluated at 1,287 CpGs in the promoters of cancer-related genes in 517 breast tumors of AA (n = 216) or non-AA (n = 301) cases in the Carolina Breast Cancer Study (CBCS).ResultsMultivariable linear regression analysis of all tumors, controlling for age, menopausal status, stage, intrinsic subtype, and multiple comparisons [false discovery rate (FDR)], identified seven CpG probes that showed significant (adjusted P < 0.05) differential methylation between AAs and non-AAs. Stratified analyses detected an additional four CpG probes differing by race within hormone receptor-negative (HR(-)) tumors. Genes differentially methylated by race included DSC2, KCNK4, GSTM1, AXL, DNAJC15, HBII-52, TUSC3, and TES; the methylation state of several of these genes may be associated with worse survival in AAs. TCGA breast tumor data confirmed the differential methylation by race and negative correlations with expression for most of these genes. Several loci also showed racial differences in methylation in peripheral blood leukocytes (PBL) from CBCS cases, indicating that these variations were not necessarily tumor-specific.ConclusionsRacial differences in the methylation of cancer-related genes are detectable in both tumors and PBLs from breast cancer cases.ImpactEpigenetic variation could contribute to differences in breast tumor development and outcomes between AAs and non-AAs.
| S-EPMC4452445 | biostudies-literature
Project description:BackgroundCDH13 (cadherin 13) is a special cadherin cell adhesion molecule, and the methylation of its promoter causes inactivation in a considerable number of human cancers. To explore the association between CDH13 promoter methylation and breast cancer risk and prognosis, we systematically integrated published articles to investigate the diagnostic performance of the CDH13 methylation test for breast cancer. An independent DNA methylation microarray dataset from The Cancer Genome Atlas project (TCGA) project was used to validate the results of the meta-analysis.MethodsThe relevant literature was searched using the PubMed, Cochrane Library, Web of Science and Google Scholar databases for articles published in English up to May 2015. Data were analyzed using random effect or fixed effect models. The effect sizes were estimated by measuring an odds ratio (OR) or hazard ratio (HR) with a 95% confidence interval (CI). A chi-squared based Q test and sensitivity analysis were performed to examine the between-study heterogeneity and the contribution of single studies to the final results, respectively. Funnel plots were constructed to evaluate publication bias.ResultsSeven hundred and twenty-six breast tumor samples and 422 controls were collected from 13 published studies. The data from the TCGA set include both tumor and normal samples. A significant association was observed between CDH13 promoter methylation and breast cancer, with an aggregated OR equal to 13.73 (95%CI: 8.09~23.31, z = 9.70, p<0.0001) as measured using the fixed effect model and 14.23 (95%CI: 5.06~40.05, z = 5.03, p<0.0001) as measured using a random effect model. The HR values were calculated as 0.77 (95%CI: 0.27~2.21, z = -0.49, p = 0.622) and 0.38 (95%CI: 0.09~1.69, z = -1.27, p = 0.20) for overall survival (OS) and disease-free survival (DFS), respectively, using the random effect model. This result indicated that breast cancer patients with CDH13 promoter methylation correlated non-significantly with prognosis and is therefore similar to the findings of the TCGA project.ConclusionsThe methylation status of CDH13 promoter was strongly associated with breast cancer risk. However, CDH13 promoter methylation was not significantly related to the OS and DFS of breast cancer and may have limited prognostic value for breast cancer patients.
| S-EPMC4859545 | biostudies-literature
Project description:PurposeEpigenetic alterations have been investigated as prognostic indicators in breast cancer but their translation into clinical practice has been impeded by a lack of appropriate validation. We present the results of a meta-analysis of the associations between RASSF1A promoter methylation status and both disease free survival (DFS) and overall survival (OS) in female breast cancer.MethodsEligible studies were identified through searching the PubMed, Web of Science and Embase databases. Studies were pooled and summary hazard ratios (HR) with corresponding confidence intervals (CIs) were calculated. Funnel plots were also carried out to evaluate publication bias.ResultsA total of 1795 patients from eight studies were included in the meta-analysis. There are eight studies which investigated DFS in 1795 cases. The relative hazard estimates ranged from 1.77-5.64 with a combined HR of 2.75 (95%CI 1.96-3.84). The HR of RASSF1A promoter methylation on DFS adjusted for other potential prognostic factors was 2.54 (95%CI 1.77-3.66). There has been five trials which analyzed the associations of RASSF1A promoter methylation status with OS in 1439 patients. The hazard estimates ranged from 1.21-6.90 with a combined random-effects estimates of 3.47 (95%CI 1.44-8.34). OS reported in multivariate analysis was evaluated in four series comprising 1346 cases and the summarized random-effects HR estimate was 3.35 (95%CI 1.14-9.85). Additionally, no publication bias was detected for both OS and DFS.ConclusionThe results of this meta-analysis suggest that RASSF1A promoter hypermethylation confers a higher risk of relapse and a worse survival in patients with breast cancer. Large prospective studies are now needed to establish the clinical utility of RASSF1A promoter methylation.
| S-EPMC3355150 | biostudies-literature
Project description:BackgroundAs downstream mediators of PI3K /PTEN /AKT /mTORC1 pathway, the AKT isoforms play critical roles in tumorgenesis. Although the pleiotropic effects of AKT1 in breast cancer have been reported, the genetic and epigenetic characteristics of AKT1 promoter region in breast cancer remains to be identified. In this study we aimed to investigate the promoter mutation spectrum, methylation and gene expression pattern of AKT1 and their relationship with breast cancer.MethodsBy using PCR target sequence enrichment and next-generation sequencing technology, we sequenced AKT1 promoter region in pairs of breast tumor and normal tissues from 95 unselected Chinese breast cancer patients. The methylation of the promoter region and the expression profile of AKT1 in the same cohort were detected with bisulfite next-generation sequencing and qPCR, respectively.ResultsWe identified 28 somatic mutations in 23 of the 95 (24.2%) breast cancer samples. And 19 of the 28 mutations were located in transcription factor (TF) binding sites. In the 23 patients with somatic mutations, no significant change of methylation or expression was found comparing with other patients. AKT1 promoter region was significantly hypo-methylated in tumor compared with matched normal tissue (P = 0.0014) in the 95 patients. The expression of AKT1 was significantly suppressed in tumor tissue (P = 0.0375). In clinicopathological factor analysis, AKT1 showed significant hypo-methylation (P = 0.0249) and suppressed expression (P = 0.0375) in HER2 negative subtype. And a trend of decrease in expression level (P = 0.0624) of AKT1 in the ER negative subtype was observed, which is significantly decreased in basal-like breast tumor (P = 0.0328).ConclusionsHypo-methylation and suppressed expression of AKT1 was observed to be associated with breast cancer in our cohort. The methylation and expression of AKT1 were both significantly associated with HER2 status. The promoter mutation of AKT1 did not show significant association with its methylation and expression status. These results suggested that the promoter mutation, methylation and gene expression of AKT1 may play distinct roles in tumorgenesis of breast cancer and the integrated analysis of methylation and expression of AKT1 might serve as potential biomarkers for diagnosis and classification of breast cancer.
| S-EPMC5354459 | biostudies-literature