Project description:ChIP followed by deep sequencing was performed with antibodies to ERalpha in U2OS-ERalpha cells treated with 17beta-estradiol. Examination of Eralpha binding sites in U2OS-Eralpha cells. Sequenced input was used as a control
Project description:The forkhead transcription factor FOXM1 is a key regulator of the cell cycle and is overexpressed in cancer. Increased levels of FOXM1 are associated with both poor prognosis and oestrogen receptor (ERalpha) status in primary breast cancer. In this study, we map FOXM1 binding genome wide in both ERalpha-positive (MCF-7) and -negative (MDA-MB-231) breast cancer cells. We identify a common set of FOXM1 binding events at cell cycle-regulating genes, but in addition, in MCF-7 cells we find a high level of concordance with ERalpha-binding regions. FOXM1 binding at these co-binding sites is dependent on ERalpha binding, as depletion of ER protein levels reduced FOXM1 binding. FOXM1 interacts directly with both ERalpha co-activator CARM1 and is required for H3 arginine methylation at the ERalpha complex. Inhibition of FOXM1 activity with the ligand thiostrepton resulted in decreased FOXM1 binding at cca. 1400 sites genome wide and reduced expression of genes correlated with poor prognosis in ERalpha-positive tumour samples. These data demonstrate a novel role for the forkhead protein FOXM1 as an ERalpha cofactor and provide insight into the role of FOXM1 in ERalpha-positive breast cancer.
Project description:The forkhead transcription factor FOXM1 is a key regulator of the cell cycle and is overexpressed in cancer. Increased levels of FOXM1 are associated with both poor prognosis and oestrogen receptor (ERalpha) status in primary breast cancer. In this study, we map FOXM1 binding genome wide in both ERalpha-positive (MCF-7) and -negative (MDA-MB-231) breast cancer cells. We identify a common set of FOXM1 binding events at cell cycle-regulating genes, but in addition, in MCF-7 cells we find a high level of concordance with ERalpha-binding regions. FOXM1 binding at these co-binding sites is dependent on ERalpha binding, as depletion of ER protein levels reduced FOXM1 binding. FOXM1 interacts directly with both ERalpha co-activator CARM1 and is required for H3 arginine methylation at the ERalpha complex. Inhibition of FOXM1 activity with the ligand thiostrepton resulted in decreased FOXM1 binding at cca. 1400 sites genome wide and reduced expression of genes correlated with poor prognosis in ERalpha-positive tumour samples. These data demonstrate a novel role for the forkhead protein FOXM1 as an ERalpha cofactor and provide insight into the role of FOXM1 in ERalpha-positive breast cancer.
Project description:Using a chromatin immunoprecipitation-paired end diTag cloning and sequencing strategy, we mapped estrogen receptor alpha (ERalpha) binding sites in MCF-7 breast cancer cells. We identified 1,234 high confidence binding clusters of which 94% are projected to be bona fide ERalpha binding regions. Only 5% of the mapped estrogen receptor binding sites are located within 5 kb upstream of the transcriptional start sites of adjacent genes, regions containing the proximal promoters, whereas vast majority of the sites are mapped to intronic or distal locations (>5 kb from 5' and 3' ends of adjacent transcript), suggesting transcriptional regulatory mechanisms over significant physical distances. Of all the identified sites, 71% harbored putative full estrogen response elements (EREs), 25% bore ERE half sites, and only 4% had no recognizable ERE sequences. Genes in the vicinity of ERalpha binding sites were enriched for regulation by estradiol in MCF-7 cells, and their expression profiles in patient samples segregate ERalpha-positive from ERalpha-negative breast tumors. The expression dynamics of the genes adjacent to ERalpha binding sites suggest a direct induction of gene expression through binding to ERE-like sequences, whereas transcriptional repression by ERalpha appears to be through indirect mechanisms. Our analysis also indicates a number of candidate transcription factor binding sites adjacent to occupied EREs at frequencies much greater than by chance, including the previously reported FOXA1 sites, and demonstrate the potential involvement of one such putative adjacent factor, Sp1, in the global regulation of ERalpha target genes. Unexpectedly, we found that only 22%-24% of the bona fide human ERalpha binding sites were overlapping conserved regions in whole genome vertebrate alignments, which suggest limited conservation of functional binding sites. Taken together, this genome-scale analysis suggests complex but definable rules governing ERalpha binding and gene regulation. Keywords: time course