Project description:RUNX1 is a transcription factor functioning both as an oncogene and a tumor suppressor in breast cancer. RUNX1 alters chromatin structure in cooperation with chromatin modifier and remodeling enzymes. In this study, we examined the relationship between RUNX1-mediated transcription and genome organization. We characterized genome-wide RUNX1 localization and performed RNA-seq and Hi-C in RUNX1-depleted and control MCF-7 breast cancer cells. RNA-seq analysis showed that RUNX1 depletion led to up-regulation of genes associated with chromatin structure and down-regulation of genes related to extracellular matrix biology, as well as NEAT1 and MALAT1 lncRNAs. Our ChIP-Seq analysis supports a prominent role for RUNX1 in transcriptional activation. About 30% of all RUNX1 binding sites were intergenic, indicating diverse roles in promoter and enhancer regulation and suggesting additional functions for RUNX1. Hi-C analysis of RUNX1-depleted cells demonstrated that overall three-dimensional genome organization is largely intact, but indicated enhanced association of RUNX1 near Topologically Associating Domain (TAD) boundaries and alterations in long-range interactions. These results suggest an architectural role for RUNX1 in fine-tuning local interactions rather than in global organization. Our results provide novel insight into RUNX1-mediated perturbations of higher-order genome organization that are functionally linked with RUNX1-dependent compromised gene expression in breast cancer cells. Hi-C and RNA-seq experiments were conducted in MCF-7 shNS and shRUNX1 cells. RUNX1 ChIP-seq was conducted in wildtype MCF-7 cells.
Project description:RUNX1 is a transcription factor functioning both as an oncogene and a tumor suppressor in breast cancer. RUNX1 alters chromatin structure in cooperation with chromatin modifier and remodeling enzymes. In this study, we examined the relationship between RUNX1-mediated transcription and genome organization. We characterized genome-wide RUNX1 localization and performed RNA-seq and Hi-C in RUNX1-depleted and control MCF-7 breast cancer cells. RNA-seq analysis showed that RUNX1 depletion led to up-regulation of genes associated with chromatin structure and down-regulation of genes related to extracellular matrix biology, as well as NEAT1 and MALAT1 lncRNAs. Our ChIP-Seq analysis supports a prominent role for RUNX1 in transcriptional activation. About 30% of all RUNX1 binding sites were intergenic, indicating diverse roles in promoter and enhancer regulation and suggesting additional functions for RUNX1. Hi-C analysis of RUNX1-depleted cells demonstrated that overall three-dimensional genome organization is largely intact, but indicated enhanced association of RUNX1 near Topologically Associating Domain (TAD) boundaries and alterations in long-range interactions. These results suggest an architectural role for RUNX1 in fine-tuning local interactions rather than in global organization. Our results provide novel insight into RUNX1-mediated perturbations of higher-order genome organization that are functionally linked with RUNX1-dependent compromised gene expression in breast cancer cells.
Project description:Background: Higher-order chromatin structure is often perturbed in cancer and other pathological states. Although several genetic and epigenetic differences have been charted between normal and breast cancer tissues, changes in higher-order chromatin organization during tumorigenesis have not been fully explored. To probe the differences in higher-order chromatin structure between mammary epithelial and breast cancer cells, we performed Hi-C analysis on MCF-10A mammary epithelial and MCF-7 breast cancer cell lines. Results: Our studies reveal that the small, gene-rich chromosomes chr16 through chr22 in the MCF-7 breast cancer genome display decreased interaction frequency with each other compared to the inter-chromosomal interaction frequency in the MCF-10A epithelial cells. Interestingly, this finding is associated with a higher occurrence of open compartments on chr16-22 in MCF-7 cells. Pathway analysis of the MCF-7 up-regulated genes located in altered compartment regions on chr16-22 reveals pathways related to repression of WNT signalling. There are also differences in intra-chromosomal interactions between the cell lines; telomeric and sub-telomeric regions in the MCF-10A cells display more frequent interactions than are observed in the MCF-7 cells. Conclusions: We show evidence of an intricate relationship between chromosomal organization and gene expression between epithelial and breast cancer cells. Importantly, this work provides a genome-wide view of higher-order chromatin dynamics and a resource for studying higher-order chromatin interactions in two cell lines commonly used to study the progression of breast cancer. Hi-C experiments were conducted in MCF-7 and MCF-10A parental cells. The RNA-seq data associated with this study is deposited under the GEO accession number GSE71862.
Project description:Background: Higher-order chromatin structure is often perturbed in cancer and other pathological states. Although several genetic and epigenetic differences have been charted between normal and breast cancer tissues, changes in higher-order chromatin organization during tumorigenesis have not been fully explored. To probe the differences in higher-order chromatin structure between mammary epithelial and breast cancer cells, we performed Hi-C analysis on MCF-10A mammary epithelial and MCF-7 breast cancer cell lines. Results: Our studies reveal that the small, gene-rich chromosomes chr16 through chr22 in the MCF-7 breast cancer genome display decreased interaction frequency with each other compared to the inter-chromosomal interaction frequency in the MCF-10A epithelial cells. Interestingly, this finding is associated with a higher occurrence of open compartments on chr16-22 in MCF-7 cells. Pathway analysis of the MCF-7 up-regulated genes located in altered compartment regions on chr16-22 reveals pathways related to repression of WNT signalling. There are also differences in intra-chromosomal interactions between the cell lines; telomeric and sub-telomeric regions in the MCF-10A cells display more frequent interactions than are observed in the MCF-7 cells. Conclusions: We show evidence of an intricate relationship between chromosomal organization and gene expression between epithelial and breast cancer cells. Importantly, this work provides a genome-wide view of higher-order chromatin dynamics and a resource for studying higher-order chromatin interactions in two cell lines commonly used to study the progression of breast cancer.
