Project description:Chromosomal structural mutations play an important role in determining the transcriptional landscape of human breast cancers. We determined that pro-oncogenic and anti-oncogenic genes are clustered throughout the genome and that these clusters coincide with regions of segmental amplification and deletion. We constructed detailed structural mutation maps of representative breast cancers and found that tandem duplications appear to nucleate regions for amplification. Subsequent rearrangements link distant pro-oncogenic elements for co-amplification, and are associated with loss of tumor suppressors. We show that genes engaged in co-amplifications or conjoint deletions on 17q and 8q have pro-growth effects that are additive in nature. Our results suggest structural mutations efficiently orchestrate the gain and loss of cancer gene cassettes that engage many oncogenic pathways simultaneously.
Project description:Mutations such as gene fusion, translocation and focal amplification are a frequent cause of proto-oncogene activation during tumorigenesis, but such mutations do not explain all cases of proto-oncogene activation. Here we show that disruption of local chromosome conformation can also activate proto-oncogenes in human cells. We mapped chromosome structures in T-cell acute lymphoblastic leukemia (T-ALL), and found that active oncogenes and silent proto-oncogenes generally occur within insulated neighborhoods formed by the looping of two interacting CTCF sites co-occupied by cohesin. Recurrent microdeletions frequently overlap neighborhood boundary sites in T-ALL genomes, and we demonstrate that site-specific perturbation of loop boundaries is sufficient to activate the respective proto-oncogenes in non-malignant cells. We found somatic genomic rearrangements affecting loop boundaries in many cancers. These results suggest that chromosome structural organization is fundamental to identify functional somatic alterations in cancer genomes.
Project description:Mutations such as gene fusion, translocation and focal amplification are a frequent cause of proto-oncogene activation during tumorigenesis, but such mutations do not explain all cases of proto-oncogene activation. Here we show that disruption of local chromosome conformation can also activate proto-oncogenes in human cells. We mapped chromosome structures in T-cell acute lymphoblastic leukemia (T-ALL), and found that active oncogenes and silent proto-oncogenes generally occur within insulated neighborhoods formed by the looping of two interacting CTCF sites co-occupied by cohesin. Recurrent microdeletions frequently overlap neighborhood boundary sites in T-ALL genomes, and we demonstrate that site-specific perturbation of loop boundaries is sufficient to activate the respective proto-oncogenes in non-malignant cells. We found somatic genomic rearrangements affecting loop boundaries in many cancers. These results suggest that chromosome structural organization is fundamental to identify functional somatic alterations in cancer genomes.
Project description:Mutations such as gene fusion, translocation and focal amplification are a frequent cause of proto-oncogene activation during tumorigenesis, but such mutations do not explain all cases of proto-oncogene activation. Here we show that disruption of local chromosome conformation can also activate proto-oncogenes in human cells. We mapped chromosome structures in T-cell acute lymphoblastic leukemia (T-ALL), and found that active oncogenes and silent proto-oncogenes generally occur within insulated neighborhoods formed by the looping of two interacting CTCF sites co-occupied by cohesin. Recurrent microdeletions frequently overlap neighborhood boundary sites in T-ALL genomes, and we demonstrate that site-specific perturbation of loop boundaries is sufficient to activate the respective proto-oncogenes in non-malignant cells. We found somatic genomic rearrangements affecting loop boundaries in many cancers. These results suggest that chromosome structural organization is fundamental to identify functional somatic alterations in cancer genomes.
Project description:Mutations such as gene fusion, translocation and focal amplification are a frequent cause of proto-oncogene activation during tumorigenesis, but such mutations do not explain all cases of proto-oncogene activation. Here we show that disruption of local chromosome conformation can also activate proto-oncogenes in human cells. We mapped chromosome structures in T-cell acute lymphoblastic leukemia (T-ALL), and found that active oncogenes and silent proto-oncogenes generally occur within insulated neighborhoods formed by the looping of two interacting CTCF sites co-occupied by cohesin. Recurrent microdeletions frequently overlap neighborhood boundary sites in T-ALL genomes, and we demonstrate that site-specific perturbation of loop boundaries is sufficient to activate the respective proto-oncogenes in non-malignant cells. We found somatic genomic rearrangements affecting loop boundaries in many cancers. These results suggest that chromosome structural organization is fundamental to identify functional somatic alterations in cancer genomes.
Project description:Chromosomal structural mutations play an important role in determining the transcriptional landscape of human breast cancers. We determined that pro-oncogenic and anti-oncogenic genes are clustered throughout the genome and that these clusters coincide with regions of segmental amplification and deletion. We constructed detailed structural mutation maps of representative breast cancers and found that tandem duplications appear to nucleate regions for amplification. Subsequent rearrangements link distant pro-oncogenic elements for co-amplification, and are associated with loss of tumor suppressors. We show that genes engaged in co-amplifications or conjoint deletions on 17q and 8q have pro-growth effects that are additive in nature. Our results suggest structural mutations efficiently orchestrate the gain and loss of cancer gene cassettes that engage many oncogenic pathways simultaneously. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from fresh-frozen breast tumors with >80% tumor cell content and their paired peripheral blood samples. Copy number analysis of the SNP arrays was done using the copy number pipeline implemented into Partek software version 6.5
Project description: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).
Project description:The RNA exosome is an evolutionarily conserved exoribonuclease complex that consists of a 3-subunit cap, a 6-subunit barrel-shaped core, and a catalytic base subunit. Missense mutations in genes encoding structural subunits of the RNA exosome cause a growing family of diseases with diverse pathologies, collectively termed RNA exosomopathies. The disease symptoms vary and can manifest as neurological defects or developmental disorders. The diversity of the RNA exosomopathy pathologies suggests that the different missense mutations in structural genes result in distinct in vivo consequences. To investigate these functional consequences and distinguish whether they are unique to each RNA exosomopathy mutation, we generated a collection of in vivo models using budding yeast by introducing pathogenic missense mutations in orthologous S. cerevisiae genes. We then performed a comparative RNA-seq analysis to assess broad transcriptomic changes in each mutant model. Three of the mutant models rrp4-G226D, rrp40-W195R and rrp46-L191H, which model mutations in the genes encoding structural subunits of the RNA exosome, EXOSC2, EXOSC3 and EXOSC5 showed the largest transcriptomic differences. Further analyses revealed shared increased transcripts enriched in translation or ribosomal RNA modification/processing pathways across the three mutant models. Studies of the impact of the mutations on translation revealed shared defects in ribosome biogenesis but distinct impacts on translation. Collectively, our results provide the first comparative analysis of several RNA exosomopathy mutant models and suggest that different RNA exosomopathy mutations result in in vivo consequences that are both unique and shared across each variant, providing more insight into the biology underlying each distinct pathology.
Project description: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.