Genome-wide analysis of RNAs translationally regulated upon BRCA1 depletion in human mammary epithelial cells
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE40730 | GEO | 2013/12/31
SECONDARY ACCESSION(S): PRJNA174769
REPOSITORIES: GEO
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Project description:Loss of function of the tumor suppressor BRCA1 (Breast Cancer 1) protein is responsible for numerous familial and sporadic breast cancers. We previously identified PABP1 as a novel BRCA1 partner and showed that BRCA1 modulates translation through its interaction with PABP1. We showed that the global translation was diminished in BRCA1-depleted cells and increased in BRCA1-overexpressing cells. Our findings raised the question whether BRCA1 affects translation of all cytoplasmic cellular mRNAs or whether it specifically targets a subset of mRNAs. In the present study, we investigated which mRNAs are regulated by BRCA1 using a microarray analysis of polysome-associated RNAs from BRCA1-depleted MCF7 cells, a human breast cancer cell line. We isolated mRNAs from the high-molecular-weight polysomes (fractions 12 to 18) and total cellular cytoplasmic mRNAs from the cytoplasmic fraction of MCF7 cells transiently expressing either siRNA directed against BRCA1 or control siRNA. Since we were interested in identifying the mRNAs that were translationally regulated by BRCA1, we determined the relative translatability of each mRNA. The relative translatability of an mRNA was determined by normalizing the change in abundance in polysomal mRNA to the change in abundance in total cytoplasmic mRNA for each mRNA.
2013-12-31 | E-GEOD-40730 | biostudies-arrayexpress
Project description:BRCA1 inactivation is a hallmark of familial breast cancer, often encountered in aggressive triple negative breast cancers. BRCA1 is a tumor suppressor with known functions in DNA repair, transcription regulation, cell cycle control, and apoptosis. In the present study, we demonstrate that BRCA1 is also a translational regulator. Based on the combination of RNA-binding protein immunoprecipitation and microarray analysis, as well as polysome profiling, we identified a subset of mRNAs translationally regulated by BRCA1 and coding for proteins whose functions play major role in cancer. We found that the level of these key proteins is similarly controlled in human mammary tumors according to their BRCA1-status. Therefore, our results propose translational control as a novel molecular mechanism with clinical relevance through which BRCA1 is a tumor suppressor.
2020-05-21 | GSE119886 | GEO
Project description:While new defects in BRCA1 are still being found, it is unclear whether current breast cancer diagnostics misses many BRCA1-associated cases. A reliable test that is able to indicate the involvement of BRCA1 deficiency in cancer genesis could support decision making in genetic counselling and clinical management. To find BRCA1-specific markers and explore the effectiveness of the current diagnostic strategy, we designed a classification method, validated it and examined whether we could find BRCA1-like breast tumours in a group of patients initially diagnosed as non-BRCA1/2 mutation carriers. A classifier was built based on array-CGH profiles of 18 BRCA1-related and 32 control breast tumours, and validated on independent sets of 16 BRCA1-related and 16 control breast carcinomas. Subsequently, we applied the classifier to 48 breast tumours of patients from Hereditary Breast and Ovarian Cancer (HBOC) families in whom no germ line BRCA1/BRCA2 mutations were identified. The classifier showed an accuracy of 91% when applied to the validation sets. In 48 non-BRCA1/2 patients, only two breast tumours presented a BRCA1-like CGH profile. Additional evidence for BRCA1 dysfunction was found in one of these tumours. We here describe the specific chromosomal aberrations in BRCA1-related breast carcinomas. We developed a predictive genetic test for BRCA1-association and show that BRCA1-related tumours can still be identified in HBOC families after routine DNA diagnostics.
2010-12-02 | GSE9021 | GEO
Project description:Most BRCA1-associated breast tumors are basal-like yet originate from luminal progenitor cells. BRCA1 is best known for its functions in DNA repair and resolution of DNA replication stress. However, it is unclear whether loss of these ubiquitously important functions of BRCA1 fully explains the cell lineage-specific increase in breast tumor development. Cell culture-based studies implicate BRCA1 in elimination of R-loops, DNA-RNA hybrid structures involved in transcriptional regulation and genetic instability. We found that BRCA1 mutation-associated R-loop accumulates preferentially in luminal epithelial cells of cancer-free human breast tissue, and at the 5' end of those genes that experience promoter-proximal RNA polymerase II (Pol II) pausing. Genetic ablation of mouse NELF-B/COBRA1, a Pol II-pausing factor and BRCA1-binding protein, in Brca1 knockout mouse mammary epithelium ameliorates R-loop accumulation and reduces mammary tumorigenesis. Our studies show that Pol II pausing is a previously unappreciated contributor to BRCA1-associated R-loop accumulation and breast cancer development.
2017-06-27 | GSE96672 | GEO
Project description:Purpose: As estrogen receptor (ER)-positive breast cancer in BRCA1 mutation carriers arises at an older age with less aggressive tumor characteristics than ER negative BRCA1 mutated breast cancer, it has been suggested that these tumors are ?sporadic? and not BRCA1-driven. With the introduction of targeted treatments specific for tumors with a non-functioning BRCA1 or BRCA2 gene, the question whether the BRCA genes are impaired in the tumor, is highly relevant. Therefore, we performed genomic profiling of BRCA1-mutated ER+ tumors. Experimental design: Genomic profiling, BRCA1 promoter methylation assessment, and loss of heterozygosity analysis were done on 16 BRCA1-mutated ER+ tumors. Results were compared with 57 BRCA1-mutated ER- tumors, 36 BRCA2-mutated ER+ associated tumors, and 182 sporadic ER+ tumors [GSE9021, GSE9114, GSE16511, GSE50407] Results: The genomic profile of BRCA1-mutated ER+ tumors was different from BRCA1-mutated ER- breast tumors, but highly similar to BRCA2-mutated ER+ tumors. In 83% of the BRCA1-mutated ER+ tumors, loss of the wildtype BRCA1 allele was observed. In addition, clinico-pathological variables in BRCA1-mutated ER+ cancer were also more similar to BRCA2-mutated ER+ and sporadic ER+ breast cancer than to BRCA1 mutated ER- cancers. Conclusions: As BRCA1-mutated ER+ tumors show a BRCAness copy number profile and LOH, it is likely that the loss of a functional BRCA1 protein plays a role in tumorigenesis in BRCA1-mutated ER+ tumors. Therefore, we hypothesize that these tumors are sensitive to drugs targeting the BRCA1 gene defect, providing new targeted treatment modalities for advanced BRCA-deficient, ER-positive breast cancer.
2016-10-01 | GSE77603 | GEO
Project description:Inactivating germline BRCA1 and BRCA2 mutations confer a defect in homologous recombination DNA repair which was found to leave traces in tumor DNA copy number aberration (CNA) profiles. In analogy to previously trained breast cancer CNA classifiers that predicted association with BRCA1 and BRCA2 mutated cancer and benefit of high dose double strand break inducing chemotherapy, we trained BRCA1 and BRCA2 classifiers on CNA profiles of 50 BRCA1 mutated, 10 BRCA2 mutated and 13 non-familial ovarian cancers and investigated whether tumor type and mutation type independent classifiers could be trained. The cross validated area under the curve of the receiver/operator characteristic curve of ovarian cancer BRCA1 and BRCA2 classifiers were 0.67 (95% CI: 0.55-0.78) and 0.91 (95% CI: 0.79-1). These classifiers identified the majority of the samples with germline and somatic BRCA1 and BRCA2 mutations and BRCA1 promoter hypermethylation in the Cancer Genome Atlas (TCGA) dataset. Combining tumor type or mutated gene did not yield higher AUCs than single gene classifiers, although the ovarian BRCA1+BRCA2 classifier identified most BRCA1 and -2 mutated cases, including those in the TCGA dataset, and a combined breast and ovarian cancer BRCA1 classifier may improve response prediction to double strand break inducing chemotherapy.
2021-12-31 | GSE111688 | GEO
Project description:Purpose: As estrogen receptor (ER)-positive breast cancer in BRCA1 mutation carriers arises at an older age with less aggressive tumor characteristics than ER negative BRCA1 mutated breast cancer, it has been suggested that these tumors are ?sporadic? and not BRCA1-driven. With the introduction of targeted treatments specific for tumors with a non-functioning BRCA1 or BRCA2 gene, the question whether the BRCA genes are impaired in the tumor, is highly relevant. Therefore, we performed genomic profiling of BRCA1-mutated ER+ tumors. Experimental design: Genomic profiling, BRCA1 promoter methylation assessment, and loss of heterozygosity analysis were done on 16 BRCA1-mutated ER+ tumors. Results were compared with 57 BRCA1-mutated ER- tumors, 36 BRCA2-mutated ER+ associated tumors, and 182 sporadic ER+ tumors [GSE9021, GSE9114, GSE16511, GSE50407]. Results: The genomic profile of BRCA1-mutated ER+ tumors was different from BRCA1-mutated ER- breast tumors, but highly similar to BRCA2-mutated ER+ tumors. In 83% of the BRCA1-mutated ER+ tumors, loss of the wildtype BRCA1 allele was observed. In addition, clinico-pathological variables in BRCA1-mutated ER+ cancer were also more similar to BRCA2-mutated ER+ and sporadic ER+ breast cancer than to BRCA1 mutated ER- cancers. Conclusions: As BRCA1-mutated ER+ tumors show a BRCAness copy number profile and LOH, it is likely that the loss of a functional BRCA1 protein plays a role in tumorigenesis in BRCA1-mutated ER+ tumors. Therefore, we hypothesize that these tumors are sensitive to drugs targeting the BRCA1 gene defect, providing new targeted treatment modalities for advanced BRCA-deficient, ER-positive breast cancer.
2016-10-01 | GSE77604 | GEO
Project description:Gene expression profiles of normal human mammary tissue from BRCA1 mutation carriers, non-BRCA1/2 mutation carriers and normal women. RNA was prepared from normal breast tissue (confirmed by pathology) from reduction mammoplasties (n=5) and prophylactic mastectomies of known BRCA1 (n=7) and non-BRCA1/2 mutation carriers (n=8). non-BRCA1/2 carriers were individuals with a strong family history of breast cancer (kConFab Category 1 (http://www.kconfab.org/Collection/Eligibility.shtml) where no mutation in BRCA1 or BRCA2 has been identified in the family by high sensitivity testing (http://www.kconfab.org/Progress/Sensitivity.shtml) of any individual affected by breast or ovarian cancer. Normal breast samples refer to reduction mammoplasty specimens, where family history is generally not known.
2009-08-01 | GSE17072 | GEO
Project description:Female BRCA1 mutation carriers have a nearly 80% probability of developing breast cancer during their life-time. We hypothesized that the breast epithelium at risk in BRCA1 mutation carriers harbors mammary epithelial cells (MECs) with altered proliferation and differentiation properties. Microarray studies revealed that PMEC colonies from BRCA1 mutation carriers anticipate expression profiles found in BRCA1-related tumors, and that the EGFR pathway is upregulated in BRCA1 mutation carriers compared ton non BRCA1 mutation carriers. Keywords: Class comparison and pathway analysis
2008-11-20 | GSE13671 | GEO
Project description:Germline and somatic mutations in BRCA1predispose to breast cancer. We found that proteasome inhibitors can selectively kill BRCA1-depleted cells. The toxic response involves a deregulation of the G1/S cell cycle checkpoint via hyperphosphorylation of RB1, 53BP1-mediated arrest at G2/M checkpoint, and ERN1-mediated unfolded protein response, culminating in a TNF receptor-mediated apoptosis. The study new unexpected molecular functions for BRCA1 protein and opens a novel possibility for the treatment of BRCA1-deficient cancers. We used microarrays to detail the global programme of gene expression underlying the response of BRCA1-deficient cells to proteasome inhibitor bortezomib.
2015-01-01 | GSE56280 | GEO