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DNA methylation profiling in the Carolina Breast Cancer Study

ABSTRACT: A microarray targeting promoters of cancer-related genes was used to evaluate DNA methylation at 935 CpG sites in 517 invasive breast tumors from the Carolina Breast Cancer Study (CBCS), a population-based study of invasive breast cancer. Concensus clustering using methylation (β) values for the 167 most variant CpG loci defined 4 clusters differing most distinctly in hormone receptor (HR) status, intrinsic subtype (luminal versus basal-like) and p53 mutation status. Supervised analyses for HR status, subtype, and p53 status identified differentially methylated CpG loci with considerable overlap (n=266). Concensus clustering also defined a hypermethylated luminal-enriched tumor cluster 3; gene ontology analysis of cluster 3 hypermethylated loci revealed enrichment for developmental genes, including homeobox domain genes (HOXB13, PAX6, IPF1, EYA4, DLK1, IHH, ISL1, TBX1, SOX1, SOX17). The hypermethylated luminal-enriched cluster 3 independently predicted poorer survival in multivariate Cox proportional hazard analysis, and this finding was confirmed in analysis of luminal A tumors. This study demonstrates epigenetic heterogeneity among breast tumors of a single intrinsic subtype, and shows that epigenetic patterns are strongly associated with HR status, subtype, and p53 mutation status. Among HR+ tumors, a gene signature characterized by hypermethylation of developmental genes may have prognostic value. Genes differentially methylated between clinically-important tumor subsets have roles in differentiation, development, and tumor growth and may be critical to inducing and maintaining tumor phenotypes and clinical outcomes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE51557 | GEO | 2015/04/07

SECONDARY ACCESSION(S): PRJNA223415

REPOSITORIES: GEO

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DNA methylation profiling in the Carolina Breast Cancer Study

Project description:A microarray targeting promoters of cancer-related genes was used to evaluate DNA methylation at 935 CpG sites in 517 invasive breast tumors from the Carolina Breast Cancer Study (CBCS), a population-based study of invasive breast cancer. Concensus clustering using methylation (β) values for the 167 most variant CpG loci defined 4 clusters differing most distinctly in hormone receptor (HR) status, intrinsic subtype (luminal versus basal-like) and p53 mutation status. Supervised analyses for HR status, subtype, and p53 status identified differentially methylated CpG loci with considerable overlap (n=266). Concensus clustering also defined a hypermethylated luminal-enriched tumor cluster 3; gene ontology analysis of cluster 3 hypermethylated loci revealed enrichment for developmental genes, including homeobox domain genes (HOXB13, PAX6, IPF1, EYA4, DLK1, IHH, ISL1, TBX1, SOX1, SOX17). The hypermethylated luminal-enriched cluster 3 independently predicted poorer survival in multivariate Cox proportional hazard analysis, and this finding was confirmed in analysis of luminal A tumors. This study demonstrates epigenetic heterogeneity among breast tumors of a single intrinsic subtype, and shows that epigenetic patterns are strongly associated with HR status, subtype, and p53 mutation status. Among HR+ tumors, a gene signature characterized by hypermethylation of developmental genes may have prognostic value. Genes differentially methylated between clinically-important tumor subsets have roles in differentiation, development, and tumor growth and may be critical to inducing and maintaining tumor phenotypes and clinical outcomes. 517 breast tumors, 9 normal breast tissues

2015-04-07 | E-GEOD-51557 | biostudies-arrayexpress

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Gene expression patterns associated with p53 status in breast cancer

Project description:Breast cancer subtypes identified in genomic studies have different underlying genetic defects. Mutations in the tumor suppressor p53 occur more frequently in estrogen receptor (ER) negative, basal-like and HER2-amplified tumors than in luminal, ER positive tumors. Thus, because p53 mutation status is tightly linked to other characteristics of prognostic importance, it is difficult to identify p53's independent prognostic effects. The relation between p53 status and subtype can be better studied by combining data from primary tumors with data from isogenic cell line pairs (with and without p53 function). In this study, the p53-dependent gene expression signatures of four cell lines (MCF-7, ZR-75-1, and two immortalized human mammary epithelial cell lines) were identified by comparing p53-RNAi transduced cell lines to their parent cell lines. Cell lines were treated with vehicle only or doxorubicin to identify p53 responses in both non-induced and induced states. Each cell line displayed unique patterns of gene expression, but cell type specific trends were evident. A common gene expression signature associated with p53 loss across all four cell lines was identified. This signature showed overlap with the signature of p53 loss in primary breast tumors and predicted relapse-free survival and overall survival in independent test data sets. Keywords: untreated x treated

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Characterizing of Breast Cancer translational PEARL clinical trial

Project description:Introduction In HR+/HER2- metastatic breast cancer (MBC) is imperative to identify patients who respond poorly to CDK4/6i and to discover therapeutic targets to reverse this resistance. Non-luminal breast cancer subtype and high levels of CCNE1 are candidate biomarkers in this setting but further validation is needed. Methods We performed mRNA gene expression profiling and correlation with progression-free-survival (PFS) on 455 tumor samples included in the phase III PEARL study, that assigned HR+/HER2- MBC patients to receive palbociclib+ET vs capecitabine. ER+/HER2- breast cancer cell lines were used to generate and characterize resistance to palbociclib+ET. Results Non-luminal subtype was more prevalent in metastatic (14%) than in primary tumor samples (4%). Patients with non-luminal tumors had median PFS of 2.4months (m) with palbociclib+ET and 9.3m with capecitabine; HR:4.16, adjusted p-value<0.0001. Tumors with high CCNE1 expression (above median) had also worse median PFS with palbociclib+ET (6.2m) than with capecitabine (9.3m); HR:1.55, adjusted p-value=0.0036. In patients refractory to palbociclib+ET (PFS in the lower quartile) we found higher levels of Polo Like Kinase 1 (PLK1). In an independent data set (PALOMA3), tumors with high PLK1 show worse median PFS than those with low PLK1 expression under palbociclib+ET treatment. In ER+/HER2- cell line models we show that PLK1 inhibition reverses resistance to palbociclib+ET. Conclusion We confirm the association of non-luminal subtype and CCNE1 with resistance to CDK4/6i+ET in HR+ MBC. High levels of PLK1 mRNA identify patients with poor response to palbociclib, suggesting PLK1 could also play a role in the setting of resistance to CDK4/6i.

2023-01-26 | GSE223700 | GEO

Over-expression of miR-146a in basal-like breast cancer cells confers enhanced tumorigenic potential in association with altered p53 status

Project description:The tumor suppressor p53 is the most frequently mutated gene in human cancers, mutated in 25-30% of breast cancers. However, mutation rates differ according to breast cancer subtype, being more prevalent in aggressive estrogen receptor (ER) negative tumors, basal-like and HER2 amplified subtypes. This heterogeneity suggests that p53 may function differently across breast cancer subtypes. We used RNAi-mediated p53 knockdown (KD) and antagomir-mediated KD of microRNAs to study how gene expression and cellular response to p53 loss differ in luminal vs. basal-like breast cancer. As expected, p53 loss caused down regulation of established p53 targets (e.g. p21 and miR-34 family) and increased proliferation in both luminal and basal-like cell lines. However, some p53-dependent changes were subtype-specific, including expression of miR-134, miR-146a, and miR-181b. To study the cellular response to miR-146a upregulation in p53-impaired basal-like lines, antagomir knockdown of miR-146a was performed. KD of miR-146a caused decreased proliferation and increased apoptosis, effectively ablating the effects of p53 loss. Furthermore, we found that miR-146a upregulation decreased NF-kB expression and downregulated the NF-kB-dependent extrinsic apoptotic pathway (including TNF, FADD, and TRADD) and antagomir-mediated miR-146a KD restored expression of these components, suggesting a plausible mechanism for miR-146a-dependent cellular responses. These findings are relevant to human basal-like tumor progression in vivo, since miR-146a is highly expressed in p53-mutant basal-like breast cancers. These findings suggest that targeting miR-146a expression may have value for altering the aggressiveness of p53 mutant basal-like tumors. reference x sample

2014-06-30 | E-GEOD-52783 | biostudies-arrayexpress

Vimentin DNA Methylation Predicts Survival in Breast Cancer

Project description:Purpose:The Vimentin gene plays a pivotal role in epithelial-to-mesenchymal transition (EMT) and is known to be over-expressed in the prognostically poor basal-like breast cancer subtype. Recent studies have reported Vimentin DNA methylation in association with poor clinical outcomes in other solid tumors, but not in breast cancer. We therefore quantified Vimentin DNA methylation in breast tumors and matched normal pairs in association with gene expression and survival in a cohort of 83 breast cancer patients. Materials and Methods:Vimentin methylation was quantified in 14 breast cell lines, 83 breast tumors, and 57 matched normal pairs using MALDI-TOF mass spectrometry. Gene expression data via qRT-PCR in cell lines, and oligo microarray data from breast tissues was correlated with percent methylation in the Vimentin promoter. A threshold of 20 percent average methylation was set for bivariate and multivariate tests of association between methylation and tumor subtype, tumor histopathology, and survival. Results:Vimentin was differentially methylated in luminal breast cancer cell lines, and in luminal A, luminal B and HER2+ breast tumor subtypes, but was rare in basal-like cell lines and tumors. Increased methylation was strongly correlated with decreased mRNA expression in cell lines, and had a moderate inverse correlation in breast tumors. Importantly, Vimentin methylation predicted poor overall survival independent of race, subtype, stage, nodal status or estrogen receptor positivity. Conclusion:Vimentin methylation predicts overall survival in breast cancer patients and holds promise as a prognostic biomarker for guiding treatment and prophylaxis. reference x sample

2013-02-19 | E-GEOD-35629 | biostudies-arrayexpress

Transcription profiling of human breast cancer cell lines to investigate p53 status in breast cancer

2008-06-12 | E-GEOD-3178 | biostudies-arrayexpress

Rb deletion in mammary stem/progenitor epithelium induces tumors with features of luminal-B or basal-like breast cancer

Project description:The retinoblastoma tumor suppressor, Rb, is implicated in luminal-B and basal-like breast carcinomas, yet its effect on mammary gland development and causal role in breast cancer subtypes remain undefined. Here we show that conditional deletion of Rb in mouse mammary epithelium led to expansion of the stem/progenitor cells and to focal acinar hyperplasia with squamous metaplasia. These uniform lesions progressed into histologically diverse, transplantable mammary adenocarcinomas and adenosquamous carcinomas with features of luminal-B or basal-like carcinomas. A subset of basal-like but none of the luminal-B tumors expressed mutant p53. These results demonstrate a causative role for Rb in the etiology of breast cancer subtypes and implicate p53 status as a determinant of tumor phenotype after Rb loss. Keywords: reference x sample Will be updated soon

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Project description:The claudin-low subtype is a recently identified rare molecular subtype of human breast cancer that expresses low levels of tight and adherens junction genes and shows high expression of epithelial-to-mesenchymal transition (EMT) genes. These tumors are enriched in gene expression signatures derived from human tumor initiating cells (TIC) and human mammary stem cells. Through cross-species analysis, we discovered mouse mammary tumors that have similar gene expression characteristics as human claudin-low tumors and were also enriched for the human TIC signature. Such claudin-low tumors were similarly rare, but came from a number of distinct mouse models including the p53 null transplant model. Here we present a molecular characterization of fifty p53 null mammary tumors as compared to other mouse models and human breast tumor subtypes. Similar to human tumors, the murine p53 null tumors fell into multiple molecular subtypes including two basal-like, a luminal, a claudin-low, and a subtype unique to this model. The claudin-low tumors also showed high gene expression of EMT inducers, low expression of the miR-200 family, and low to absent expression of both claudin 3 and E-cadherin. These murine subtypes also contained distinct genomic DNA copy number changes some of which are similarly altered in their cognate human subtype counterpart. Finally, limiting dilution transplantation revealed that p53 null claudin-low tumors are highly enriched for TICs as compared to the more common adenocarcinomas arising in the same model, thus providing a novel preclinical mouse model to investigate the therapeutic response of TICs. 107 Agilent CGH and expression microarrays

2011-08-14 | E-GEOD-27101 | biostudies-arrayexpress

The retinoblastoma gene is targeted for rearrangements in BRCA1-deficient basal-like breast cancer.

Project description:Breast tumors from BRCA1 germ line mutation carriers typically exhibit features of the basal-like molecular subtype. However, the specific genes recurrently mutated as a consequence of BRCA1 dysfunction have not been fully elucidated. In this study, we utilized gene expression profiling to molecularly subtype 577 breast tumors, including 73 breast tumors from BRCA1/2 mutation carriers. Focusing on the RB1 locus, we analyzed 33 BRCA1-mutated, 36 BRCA2-mutated and 48 non-BRCA1/2-mutated breast tumors using a custom-designed high-density oligomicroarray covering the RB1 gene. We found a strong association between the basal-like subtype and BRCA1-mutated breast tumors and the luminal B subtype and BRCA2-mutated breast tumors. RB1 was identified as a major target for genomic disruption in tumors arising in BRCA1 mutation carriers and in sporadic tumors with BRCA1 promoter-methylation, but rarely in other breast cancers. Homozygous deletions, intragenic breaks, or microdeletions were found in 33% of BRCA1-mutant tumors, 36% of BRCA1 promoter-methylated basal-like tumors, 13% of non-BRCA1 deficient basal-like tumors, and 3% of BRCA2-mutated tumors. In addition, RB1 was frequently inactivated by gross gene disruption in BRCA1-related hereditary breast cancer and BRCA1-methylated sporadic basal-like breast cancer, but rarely in BRCA2-hereditary breast cancer and non-BRCA1-deficient sporadic breast cancers. Together, our findings demonstrate the existence of genetic heterogeneity within the basal-like breast cancer subtype that is based upon BRCA1-status. Gene expression profiling of breast tumors. Dual color common reference gene expression study using 55K oligonucleotide microarrays.

2012-06-26 | E-GEOD-25307 | biostudies-arrayexpress

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