Discovering interactions among BRCA1 and other candidate genes associated with sporadic breast cancer.
Ontology highlight
ABSTRACT:
SUBMITTER: Lo SH
PROVIDER: S-EPMC2517604 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:BackgroundPromoter methylation is a common epigenetic mechanism to silence tumor suppressor genes during breast cancer development. We investigated whether BRCA1-associated breast tumors show cancer-predictive methylation patterns similar to those found in sporadic tumors.Patients and methodsQuantitative multiplex methylation-specific PCR of 11 genes involved in breast carcinogenesis (RARB, RASSF1, TWIST1, CCND2, ESR1, SCGB3A1, BRCA1, BRCA2, CDKN2A, APC, CDH1) was carried out on 32 BRCA1-associated and 46 sporadic breast carcinomas and on normal breast tissue from seven BRCA1 mutation carriers and 13 non-carriers.ResultsThe extent of cumulative methylation increased with age (P < 0.001). The median cumulative methylation index (CMI) of all studied genes was significantly higher in tumors (89) than in normal tissue (13, P < 0.001). The median CMI was significantly lower in BRCA1-associated (59) than in sporadic breast tumors (122, P = 0.001), in estrogen receptor (ER)-negative tumors (73) than in ER-positive tumors (122, P = 0.005) and in lymph node-negative (77) compared with lymph node-positive tumors (137, P = 0.007). In subgroup analysis, the effect of a BRCA1 germline mutation on methylation proved to be independent of ER status, lymph node status and age.ConclusionsThese data indicate that BRCA1-associated breast cancers show less promoter methylation compared with sporadic breast carcinomas indicating a difference in disease etiology.
| S-EPMC2733079 | biostudies-literature
Project description:To test the hypothesis that altered expression of BRCA1 protein may play an important role in sporadic breast cancer development, 50 randomly selected primary breast cancers (frozen sections, 5 years' median follow-up) were immunolabelled with two monoclonal BRCA1 antibodies (MS110 and MS13). MS110 labelling was exclusively nuclear showing no relation to outcome or tumour pathology. Western blotting demonstrated crossreactivity, suggesting antibody nonspecificity. MS13 labelling was predominantly cytoplasmic. Intense labelling predicted decreased overall survival (P=0.012), disease-free survival (P=0.029), oestrogen receptor negativity (P=0.0004) and c-erbB-2 overexpression (P=0.006). Western blotting detected a 110 kDa molecule consistent with BRCA1 delta11b splice variant. BRCA1 protein is postulated to function as a tumour suppressor. We demonstrate cytoplasmic localisation in sporadic breast cancer suggesting excess delta11b splice variant production, reduced production of full-length BRCA1 and thus postulate reduced tumour suppressor activity. BRCA1 protein appears to have a significant role in both sporadic and hereditary breast cancers.
| S-EPMC2747570 | biostudies-other
Project description:Inherited BRCA1 mutations confer elevated cancer risk. Recent studies have identified genes that encode proteins that interact with BRCA1 as modifiers of BRCA1-associated breast cancer. We evaluated a comprehensive set of genes that encode most known BRCA1 interactors to evaluate the role of these genes as modifiers of cancer risk. A cohort of 2,825 BRCA1 mutation carriers was used to evaluate the association of haplotypes at ATM, BRCC36, BRCC45 (BRE), BRIP1 (BACH1/FANCJ), CTIP, ABRA1 (FAM175A), MERIT40, MRE11A, NBS1, PALB2 (FANCN), RAD50, RAD51, RAP80, and TOPBP1, and was associated with time to breast and ovarian cancer diagnosis. Statistically significant false discovery rate (FDR) adjusted P values for overall association of haplotypes (P(FDR)) with breast cancer were identified at ATM (P(FDR) = 0.029), BRCC45 (P(FDR) = 0.019), BRIP1 (P(FDR) = 0.008), CTIP (P(FDR) = 0.017), MERIT40 (P(FDR) = 0.019), NBS1 (P(FDR) = 0.003), RAD50 (P(FDR) = 0.014), and TOPBP1 (P(FDR) = 0.011). Haplotypes at ABRA1 (P(FDR) = 0.007), BRCC45 (P(FDR) = 0.016 and P(FDR) = 0.005 in two haplotype blocks), and RAP80 (P(FDR) < 0.001) were associated with ovarian cancer risk. Overall, the data suggest that genomic variation at multiple loci that encode proteins that interact biologically with BRCA1 are associated with modified breast cancer and ovarian cancer risk in women who carry BRCA1 mutations.
| S-EPMC3170727 | biostudies-literature
Project description:BackgroundWhile a number of studies have examined miRNA profiles across the molecular subtypes of breast cancer, it is unclear whether BRCA1 basal-like cancers have a specific miRNA profile. This study aims to compare grade independent miRNA expression in luminal cancers, sporadic and BRCA1 basal-type breast cancers. It also aims to ascertain an immunohistochemical profile regulated by BRCA1 specific miRNAs for potential diagnostic use.MethodsmiRNA expression was assessed in 11 BRCA1 basal, 16 sporadic basal, 17 luminal grade 3 cancers via microarrays. The expression of Cyclin D1, FOXP1, FIH-1, pan-ERβ, NRP1 and CD99, predicted to be regulated by BRCA1 specific miRNAs by computer prediction algorithms, was assessed via immunohistochemistry in a cohort of 35 BRCA1 and 52 sporadic basal-like cancers. Assessment of cyclin D1, FOXP1, NRP1 and CD99 expression was repeated on a validation cohort of 82 BRCA1 and 65 sporadic basal-like breast cancers.ResultsUnsupervised clustering of basal cancers resulted in a "sporadic" cluster of 11 cancers, and a "BRCA1" cluster of 16 cancers, including a subgroup composed entirely of 10 BRCA1 cancers. Compared with sporadic basal cancers, BRCA1 cancers showed reduced positivity for proteins predicted to be regulated by miRNAs: FOXP1 (6/20[30 %] vs. 37/49[76 %], p < 0.001), cyclin D1 (8/22[36 %] vs. 30/46[65 %], p = 0.025), NRP1 (2/20[10 %] vs. 23/46[50 %], p = 0.002). This was confirmed in the validation cohort (all p < 0.001). Negative staining for 2 or more out of FOXP1, cyclin D1 and NRP1 predicts germline BRCA1 mutation with a sensitivity of 92 %, specificity of 44 %, positive predictive value of 38 % and a negative predictive value of 94 %.ConclusionSporadic and BRCA1 basal-like cancers have grade independent miRNA expression profiles. Furthermore miRNA driven differences in the expression of proteins in BRCA1 basal cancers may be detected via immunohistochemistry. These findings may have important diagnostic implications, as immunohistochemical assessment of basal cancers, in addition to the patient's family and clinical history, may potentially identify patients who may benefit from BRCA1 gene testing.
| S-EPMC4494690 | biostudies-literature
Project description:Analysis of miRNA expression in grade 3 luminal, sporadic and BRCA1 associated basal-like breast cancers 44 primary grade III breast cancer (11 BRCA1 basal, 16 sporadic basal, 17 luminal) and 13 normal breast FFPE (formalin fixed, paraffin embedded) specimens, plus 7 controls and 5 cell lines were analysed. The aim of the study was to derive grade-specific miRNA signatures for sporadic and BRCA1 basal-like breast cancers, and to ascertain an immunohistochemical profile regulated by BRCA1 specific miRNAs for potential diagnostic uses.
| S-ECPF-GEOD-61438 | biostudies-other
Project description:BRCA1 mutation carriers have an 85% risk of developing breast cancer but the risk of developing non-hereditary breast cancer is difficult to assess. Our objective is to test whether a DNA methylation (DNAme) signature derived from BRCA1 mutation carriers is able to predict non-hereditary breast cancer.In a case/control setting (72 BRCA1 mutation carriers and 72 BRCA1/2 wild type controls) blood cell DNA samples were profiled on the Illumina 27 k methylation array. Using the Elastic Net classification algorithm, a BRCA1-mutation DNAme signature was derived and tested in two cohorts: (1) The NSHD (19 breast cancers developed within 12 years after sample donation and 77 controls) and (2) the UKCTOCS trial (119 oestrogen receptor positive breast cancers developed within 5 years after sample donation and 122 controls).We found that our blood-based BRCA1-mutation DNAme signature applied to blood cell DNA from women in the NSHD resulted in a receiver operating characteristics (ROC) area under the curve (AUC) of 0.65 (95% CI 0.51 to 0.78, P?=?0.02) which did not validate in buccal cells from the same individuals. Applying the signature in blood DNA from UKCTOCS volunteers resulted in AUC of 0.57 (95% CI 0.50 to 0.64; P?=?0.03) and is independent of family history or any other known risk factors. Importantly the BRCA1-mutation DNAme signature was able to predict breast cancer mortality (AUC?=?0.67; 95% CI 0.51 to 0.83; P?=?0.02). We also found that the 1,074 CpGs which are hypermethylated in BRCA1 mutation carriers are significantly enriched for stem cell polycomb group target genes (P <10(-20)).A DNAme signature derived from BRCA1 carriers is able to predict breast cancer risk and death years in advance of diagnosis. Future studies may need to focus on DNAme profiles in epithelial cells in order to reach the AUC thresholds required of preventative measures or early detection strategies.
| S-EPMC4110671 | biostudies-literature
Project description:IntroductionBRCA1 or BRCA2 germline mutations increase the risk of developing breast cancer. Tumour cells from germline mutation carriers have frequently lost the wild-type allele. This is predicted to result in genomic instability where cell survival depends upon dysfunctional checkpoint mechanisms. Tumorigenic potential could then be acquired through further genomic alterations. Surprisingly, somatic BRCA mutations are not found in sporadic breast tumours. BRCA1 methylation has been shown to occur in sporadic breast tumours and to be associated with reduced gene expression. We examined the frequency of BRCA1 methylation in 143 primary sporadic breast tumours along with BRCA1 copy number alterations and tumour phenotype.MethodsPrimary sporadic breast tumours were analysed for BRCA1alpha promoter methylation by methylation specific PCR and for allelic imbalance (AI) at BRCA1 and BRCA2 loci by microsatellite analysis and TP53 (also known as p53) mutations by constant denaturing gel electrophoresis. The BRCA1 methylated tumours were analysed for BRCA1 copy alterations by fluorescence in situ hybridisation and BRCA1 expression by immunostaining.ResultsBRCA1 methylation was found in 13/143 (9.1%) sporadic breast tumours. The BRCA1 methylated tumours were significantly associated with estrogen receptor (ER) negativity (P = 0.0475) and displayed a trend for BRCA1 AI (P = 0.0731) as well as young-age at diagnosis (< or = 55; P = 0.0898). BRCA1 methylation was not associated with BRCA2 AI (P = 0.5420), although a significant association was found between BRCA1 AI and BRCA2 AI (P < 0.0001).Absent/markedly reduced BRCA1 expression was observed in 9/13 BRCA1 methylated tumours, most of which had BRCA1 deletion. An elevated TP53 mutation frequency was found among BRCA1 methylated tumours (38.5%) compared with non-methylated tumours (17.2%). The BRCA1 methylated tumours were mainly of tumour grade 3 (7/13) and infiltrating ductal type (12/13). Only one methylated tumour was of grade 1.ConclusionBRCA1 methylation is frequent in primary sporadic breast tumours. We found an indication for BRCA1 methylation to be associated with AI at the BRCA1 locus. Almost all BRCA1 methylated tumours with absent/markedly reduced BRCA1 expression (8/9) displayed BRCA1 deletion. Thus, epigenetic silencing and deletion of the BRCA1 gene might serve as Knudson's two 'hits' in sporadic breast tumorigenesis. We observed phenotypic similarities between BRCA1 methylated and familial BRCA1 tumours, based on BRCA1 deletion, TP53 mutations, ER status, young age at diagnosis and tumour grade.
| S-EPMC1779478 | biostudies-literature
Project description:BackgroundThe role of somatic BRCA1/2 gene mutations in breast cancer is getting increasing attention in view of hereditary disease. The medullary phenotype and triple negative intrinsic subtypes are often, but not exclusively encountered in BRCA1 germline mutated breast cancer, whilst for BRCA2, no association to specific histological features are known. In this study, we addressed the relationship between morphological medullary phenotype and BRCA1/2 somatic mutations in breast cancer without known positive family anamnesis.Methods32 clinically sporadic breast cancers with medullary features were analyzed for somatic BRCA1/2 mutations (all coding exons) with next-generation sequencing technology. Paraffin-embedded formalin-fixed breast cancer samples from all patients were analyzed.ResultsThree of 32 tumors (9%) had pathogenic (ARUP class-5) BRCA1 gene alterations. Two of these pathogenic variants exhibited deletions leading to frameshift mutations (p.Glu23fs, p.Val1234fs), and the remaining single-nucleotid-variant resulted in premature STOP codon (p.Glu60Ter). In one patient, the same pathogenic BRCA1 mutation was detected (p.Glu23fs) in normal breast tissue. Retrospective follow-up in two patients revealed a positive family history for breast cancer and consecutive germline mutation testing confirmed presence of BRCA1 mutations. No somatic pathogenic BRCA2 mutations were detected.ConclusionsBRCA1 mutation testing may be useful in clinically sporadic breast cancer patients with medullary features to identify potential mutation carriers independently from intrinsic molecular subtype. Formalin-fixed paraffin-embedded cancer tissue can undergo testing within a routine molecular-diagnostic setting as a clinical BRCA1/2 mutation screening strategy.
| S-EPMC5916977 | biostudies-literature
Project description:One of the greatest challenges facing human geneticists is the identification and characterization of susceptibility genes for common complex multifactorial human diseases. This challenge is partly due to the limitations of parametric-statistical methods for detection of gene effects that are dependent solely or partially on interactions with other genes and with environmental exposures. We introduce multifactor-dimensionality reduction (MDR) as a method for reducing the dimensionality of multilocus information, to improve the identification of polymorphism combinations associated with disease risk. The MDR method is nonparametric (i.e., no hypothesis about the value of a statistical parameter is made), is model-free (i.e., it assumes no particular inheritance model), and is directly applicable to case-control and discordant-sib-pair studies. Using simulated case-control data, we demonstrate that MDR has reasonable power to identify interactions among two or more loci in relatively small samples. When it was applied to a sporadic breast cancer case-control data set, in the absence of any statistically significant independent main effects, MDR identified a statistically significant high-order interaction among four polymorphisms from three different estrogen-metabolism genes. To our knowledge, this is the first report of a four-locus interaction associated with a common complex multifactorial disease.
| S-EPMC1226028 | biostudies-literature
Project description:When triple negative breast cancer (TNBC) are analyzed by gene expression profiling different subclasses are identified, at least one characterized by genes related to immune signaling mechanisms supporting the role of these genes in the cancers. In an earlier study we observed differences in TNBC cell lines with respect to their expression of the cytokine IL32. Our analyses showed that certain cell lines expressed higher levels of the cytokine compared to others. Because TNBC are heterogeneous and immune-related genes appear to play a pivotal role in these cancers, we chose to examine the transcriptomes of the different cell lines based on IL32 expression. We performed group analyses of TNBC cell lines demonstrating high IL32 compared to low IL32 levels and identified IL32, GATA3, MYBL1, ETS1, PTX3 and TMEM158 as differentially associated with a subpopulation of TNBC. The six candidate genes were validated experimental and in different patient datasets. The genes distinguished a subset of TNBC from other TNBC, and TNBC from normal, luminal A, luminal B, and HER2 patient samples. The current project serves as a preliminary study in which we outline the discovery and validation of our list of six candidate genes.
| S-EPMC5620011 | biostudies-literature