Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Chromosome as oncogenic organizer: functional consequences of structural mutations in breast cancer (RNA-Seq)

ABSTRACT: Chromosomal structural mutations play an important role in determining the transcriptional landscape of human breast cancers. To assess the nature of these structural mutations, we analyzed a representative sampling of the major types of breast tumor samples for detailed structural mutations using paired-end tag sequencing of long-insert genomic DNA (DNA-PET) with matched transcriptome ascertainment by RNA-seq. Compared with other structural mutations, tandem duplications are enriched around partners of fusion transcripts and demarcate regions of high gene expression. Moreover tandem duplications appear to be early events in tumor evolution by facilitating subsequent downstream amplification and deletion of important adjacent cancer associated genes. In a detailed reconstruction of events in chr17, we found large unpaired-inversions connect a duplicated ERBB2 with neighboring 17q21.3 amplicons while simultaneously deleting the intervening BRCA1 tumor suppressor locus. Using siRNAs in breast cancer cell lines, we showed that the 17q21.3 amplicon harbored a significant number of weak oncogenes that appeared consistently co-amplified in primary tumors. Down-regulation of BRCA1 expression augmented the cell proliferation in human normal mammary epithelial cells. Finally, using in silico approaches, we determined that genes whose expression in breast tumors are associated with either poor or good clinical prognosis appear clustered together in segments of frequent amplification or deletion, suggesting that structural abnormalities induce the loss or gain of blocks of adjacent genes with oncogenic or growth suppressor function. These analyses suggest that structural mutations efficiently orchestrate the gain and loss of cancer gene cassettes that engage many oncogenic pathways simultaneously. RNA sequencing of four primary breast cancer RNA samples (SOLiD, Applied Biosystems).

ORGANISM(S): Homo sapiens

SUBMITTER: Edison Liu

PROVIDER: E-GEOD-57914 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:We obtained peripheral blood samples for women from Utah (USA) and Ontario (Canada) who had a family history of breast cancer (or did not), who carried a BRCA1/2 mutation (or did not), and who had developed breast cancer (or had not). We classified the women into two groups: [1] those who had a family history of breast cancer (irrespective of BRCA1/2 mutation status) and had developed an early-onset breast tumor and [2] those who had a family history of breast cancer but had not developed a breast tumor or who did not have a family history of breast cancer (some of whom had developed sporadic breast cancer and and others who had not). We then used machine-learning methods to assess how well we could classify these women into either group. The Utah samples served as a training set, and the Ontario samples served as an independent validation set from a geographically distinct population. For the Utah cohort, there are 124 samples total: 16 who had a family history of breast cancer and carried a BRCA mutation and had developed breast cancer, 23 with a family history of breast cancer but did not carry a BRCA1/2 mutation and had developed breast cancer, 22 with a family history of breast cancer and carried a BRCA1/2 mutation but had not developed breast cancer, 22 with a family history of breast cancer but did not carry a BRCA1/2 mutation and had not developed breast cancer, 22 with no family history of breast cancer and had developed breast cancer, and 19 with no family history of breast cancer and had not developed breast cancer. The Ontario cohort included 73 samples: 11 who had a family history of breast cancer and carried a BRCA mutation and had developed breast cancer, 17 with a family history of breast cancer but did not carry a BRCA1/2 mutation and had developed breast cancer, 14 with a family history of breast cancer and carried a BRCA1/2 mutation but had not developed breast cancer, 18 with a family history of breast cancer but did not carry a BRCA1/2 mutation and had not developed breast cancer, 8 with no family history of breast cancer and had developed breast cancer, and 5 with no family history of breast cancer and had not developed breast cancer. 36 of the Ontario samples were scanned and processed at Duke University; the remaining 37 samples were handled at Boston University. The batch-adjustment process was repeated twice independently: [1] all 124 Utah samples were adjusted jointly with the 36 Ontario samples that had been processed at Duke University (set 1) and [2] all 124 Utah samples were adjusted jointly with the 37 Ontario samples that had been processed at Boston University (set 2). This dataset represents set 1.

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Chromosome as oncogenic organizer: functional consequences of structural mutations in breast cancer (RNA-Seq)

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