Unknown,Transcriptomics,Genomics,Proteomics

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

ABSTRACT: 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

ORGANISM(S): Mus musculus

SUBMITTER: Charles Perou

PROVIDER: E-GEOD-14457 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Rb deletion in mouse mammary progenitors induces luminal-B or basal-like/EMT tumor subtypes depending on p53 status.

Jiang Zhe Z Deng Tao T Jones Robert R Li Huiqin H Herschkowitz Jason I JI Liu Jeff C JC Weigman Victor J VJ Tsao Ming-Sound MS Lane Timothy F TF Perou Charles M CM Zacksenhaus Eldad E

The Journal of clinical investigation 20100802 9

Breast cancer is a highly heterogeneous disease, with several different subtypes being characterized by distinct histology, gene expression patterns, and genetic alterations. The tumor suppressor gene retinoblastoma 1 (RB1) is frequently lost in both luminal-B and triple-negative tumor (TNT; i.e., estrogen receptor-, progesterone receptor-, and human epidermal growth factor receptor 2-negative) breast cancer subtypes. However, a causal role for RB1 loss in different subtypes remains undefined. H ...[more]

PMID: 20679727

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Project description:Metaplastic breast cancers (MBC) are aggressive, chemoresistant tumors characterized by lineage plasticity. To advance understanding of their pathogenesis and relatedness to other breast cancer subtypes, 28 MBCs were compared with common breast cancers using comparative genomic hybridization, transcriptional profiling, and reverse-phase protein arrays and by sequencing for common breast cancer mutations. MBCs showed unique DNA copy number aberrations compared with common breast cancers. PIK3CA mutations were detected in 9 of 19 MBCs (47.4%) versus 80 of 232 hormone receptor-positive cancers (34.5%; P = 0.32), 17 of 75 HER-2-positive samples (22.7%; P = 0.04), 20 of 240 basal-like cancers (8.3%; P < 0.0001), and 0 of 14 claudin-low tumors (P = 0.004). Of 7 phosphatidylinositol 3-kinase/AKT pathway phosphorylation sites, 6 were more highly phosphorylated in MBCs than in other breast tumor subtypes. The majority of MBCs displayed mRNA profiles different from those of the most common, including basal-like cancers. By transcriptional profiling, MBCs and the recently identified claudin-low breast cancer subset constitute related receptor-negative subgroups characterized by low expression of GATA3-regulated genes and of genes responsible for cell-cell adhesion with enrichment for markers linked to stem cell function and epithelial-to-mesenchymal transition (EMT). In contrast to other breast cancers, claudin-low tumors and most MBCs showed a significant similarity to a "tumorigenic" signature defined using CD44(+)/CD24(-) breast tumor-initiating stem cell-like cells. MBCs and claudin-low tumors are thus enriched in EMT and stem cell-like features, and may arise from an earlier, more chemoresistant breast epithelial precursor than basal-like or luminal cancers. PIK3CA mutations, EMT, and stem cell-like characteristics likely contribute to the poor outcomes of MBC and suggest novel therapeutic targets. Comparison of reference samples against treatment

Project description:Introduction: In breast cancers, the basal-like subtype has high levels of genomic instability relative to other breast cancer subtypes with many basal-like-specific regions of aberration. There is evidence that this genomic instability extends to smaller scale genomic aberrations as well, as shown by a previously described micro-event in the PTEN gene in the Basal-like SUM149 breast cancer cell line. Methods: We sought to identify if small regions of genomic change exist by using a high density, gene centric Comparative Genomic Hybridizations (CGH) array on both cell lines and primary tumors. A custom Agilent tiling array for CGH (244,000 probes, 200bp tiling resolution) was created to identify small regions of genomic change and was focused on previously identified basal-like-specific, and general cancer genes. Tumor genomic DNA from 94 patients and 2 breast cancer cell lines was labeled and hybridized to these arrays. Aberrations were called using SWITCHdna and the smallest 25% of SWITCHdna-defined genomic segments being called micro-aberrations (<64 contiguous probes, ~ <15kb). Results: Our data showed that primary tumor breast cancer genomes frequently contained areas of small-scale copy number gains and losses, termed micro-aberrations, which are undetectable using lower-density genome-wide platforms. The basal-like subtype exhibited the highest incidence of these events. These micro-aberrations sometimes altered expression of the involved gene as suggested by data from microarray and mRNA-seq studies. We confirmed the presence of the PTEN micro-amplification in SUM149 and by mRNA-seq showed that this resulted in loss of expression of all exons downstream of this event. Micro-aberrations disproportionately affected the 5’ regions of the affected genes, including the promoter region, and a high frequency of micro-aberrations was associated with poor survival outcomes. Conclusion: Using a high probe density, gene-centric aCGH microarray, we present evidence of small-scale genomic aberrations that contribute to gene inactivation, and thus, genomic instability and tumor formation through a mechanism not detected using conventional copy number analyses. reference x sample

Dataset Information

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

Publications

Rb deletion in mouse mammary progenitors induces luminal-B or basal-like/EMT tumor subtypes depending on p53 status.

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