Unknown,Transcriptomics,Genomics,Proteomics

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Microarray-based gene expression data from BPLER tumor explants.

ABSTRACT: The gene expression of 6 different mouse xenografts initiated by BPLER cells analyzed by microarray. Basal-like triple negative breast cancers (TNBC) have poor prognosis. To study the basal-like transcriptional profile of tumors transformed by defined genetic elements, the human breast epithelial cell line BPLER was injected into NOD/SCID mice. The resulting tumors were excised for expression analysis. Keywords: breast cancer, BPLER, metastasis, tumor stem cells, tumor initiating cells, breast adenocarcinoma BPLER cells were derived from human primary breast epithelial cells propagated in WIT medium (Ince et al, Cancer Cell, 2007). These cells were transformed with hTERT, SV40 early region and hRASV12 by retroviral transduction. BPLER have a TNBC-like phenotype in vitro and are highly enriched for tumor-initiating cells. To define the phenotype of BPLER-derived tumors in vivo, BPLER cells were injected in the mammary fat-pad of 6 NOD/SCID mice. Once tumors were palpable, mice were sacrificed and tumors excised. Total RNA was extracted using Trizol. The gene expression profile of each tumor was assessed by mRNA microarray analysis. Based on histology and principal component analysis of microarray data, BPLER tumors were remarkably similar to human primary TNBC encountered in the clinic (Petrocca et al, Cancer Cell, 2013).

ORGANISM(S): Homo sapiens

SUBMITTER: Tan Ince

PROVIDER: E-GEOD-48444 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The breast tumor microenvironment plays an active role in tumorigenesis. Molecular alterations, including epigenetic modifications to DNA, and changes in RNA and protein expression have been identified in tumor-associated stroma; however, there is considerable debate as to whether the stroma is characterized by genomic instability or whether detection of chromosomal alterations in the breast stroma is a reflection of technological artifact rather than the true genomic content of the tumor microenvironment. Methods: Surgically-removed breast stroma specimens from 112 women undergoing reductive mammoplasty (n=15), prophylactic mastectomy (N=6) or mastectomy for a diagnosis of breast disease (n=92) were frozen in optimal cutting temperature medium. Allelic imbalance (AI) analysis was performed in 484 stromal specimens from 98 women using a panel of 52 microsatellite markers; SNP data was generated from a subset of 86 stromal specimens using 250K SNP arrays (Affymetrix). Copy number alterations were identified using Partek Genomics Suite. Results: AI was not detected in 92% (444/484) of stroma specimens. When compared to previously generated AI data from 77 formalin-fixed, paraffin-embedded stroma specimens (Ellsworth et al., Ann Surg Oncol 2004), 32 (42%) of which harbored at least one detectable AI event, the frequency of AI in the FFPE specimens (4.62%) was significantly higher (P<0.0001) than that found in frozen specimens (0.45%). Of the stroma specimens assayed using SNP arrays 95% (82/86) had no detectable alterations and the 11 copy number changes were small and not shared between specimens. Conclusions: The data presented here support a model in which the tumor microenvironment is genetically stable. The direct comparison of copy number alterations between FFPE and frozen research-grade specimens using identical methodologies suggests that past reports of significant AI in breast stroma, both adjacent to and distant from the tumor, reflects artifact in the archival specimens caused by formalin-fixation, paraffin-embedding and tissue storage. 250K STY data was generated for 86 breast stromal specimens. The tissue specimens were analyzed by paired analysis to the SNP data from matched genomic (blood) DNAs

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Microarray-based gene expression data from BPLER tumor explants.

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