Project description:This SuperSeries is composed of the following subset Series: GSE25314: FoxA1 is a critical determinant of Estrogen Receptor function and endocrine response (part I) GSE25315: FoxA1 is a critical determinant of Estrogen Receptor function and endocrine response (part II) Refer to individual Series
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts. breast cancer MCF-7 cell lines were treaated in the presence of Estrogen, Estrogen plus Tamoxifen, Tamoxifen or a vehicle. MCF-7 cells were hormone-depleted for 3 d and treated with 100 nM estrogen or 1 microM Tamoxifen for 6 h. There were four biological replicates for each of the four different groups.
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts. FoxA1 silenced breast cancer MCF-7 cell lines or control siRNA in the presence of Estrogen or a vehicle. MCF-7 cells were hormone-depleted for 3 d and treated with 100 nM estrogen for 6 h. There were three biological replicates for each of the four different groups.
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts.
Project description:Estrogen Receptor-a (ER) is the key feature in the majority of breast cancers and ER binding to the genome correlates with the Forkhead protein FOXA1 (HNF3a), but mechanistic insight is lacking. We now show that FOXA1 is the defining factor that governs differential ER-chromatin interactions. We show that almost all ER-chromatin interactions and gene expression changes are dependent on the presence of FOXA1 and that FOXA1 dictates genome-wide chromatin accessibility. Furthermore, we show that CTCF is an upstream negative regulator of FOXA1-chromatin interactions. In ER responsive breast cancer cells, the dependency on FOXA1 for tamoxifen-ER activity is absolute and in tamoxifen resistant cells, ER binding occurs independently of ligand, but in a FOXA1 dependent manner. Importantly, expression of FOXA1 in non-breast cancer cells is sufficient to alter ER binding and response to endocrine treatment. As such, FOXA1 is the primary determinant that regulates estrogen-ER activity and endocrine response in breast cancer cells and is sufficient to program ER functionality in non-breast cancer contexts.
Project description:<p>The genomic evolution of breast cancers exposed to systemic therapy and its effects on clinical outcome have not been broadly characterized. We integrated the genomic sequencing of 1918 breast cancers, including 1501 hormone receptor-positive tumors, with detailed clinical information and treatment outcomes. Functional mutations in ERBB2 and loss-of-function mutations in NF1 were more than twice as common in post-endocrine therapy tumors compared to treatment-naive tumors. Additional alterations in the MAPK pathway (EGFR, KRAS among others) and in estrogen receptor transcriptional regulators (MYC, CTCF, FOXA1 and TBX3) were also more common compared to hormonal therapy-naive tumors.</p> <p>To determine whether candidate genomic lesions in the MAPK pathway and estrogen receptor transcriptional regulators were present prior to therapy or whether such lesions arose under the selective pressure of therapy, we performed whole-exome sequencing in select patients who had adequate samples acquired prior to and after progression on endocrine therapy. In total, 95 specimens corresponding to 30 treatment-naive primary tumors, 35 post-treatment tumors, and 30 normal samples were sequenced from 30 patients with endocrine-resistant metastatic breast cancer.</p>
Project description:Aberrant activation of the forkhead protein FOXA1 is observed in advanced hormone-related cancers. However, to date, key mediators of high FOXA1 signaling remain elusive. We demonstrate that ectopic high FOXA1 (H-FOXA1) expression promotes estrogen receptor-positive (ER+) breast cancer (BC) metastasis in a xenograft mouse model. Mechanistically, H-FOXA1 reprograms ER-chromatin binding to elicit a core gene signature (CGS) highly enriched in ER+ endocrine-resistant (EndoR) cells. We identified Secretome14, a CGS subset encoding ER-dependent cancer secretory proteins, strongly predicts poor outcomes of ER+ BC and is elevated in ER+ metastases vs. primary tumors, irrespective to the ESR1 mutations. Parental (P) ER+ BC cells and their endocrine-resistant (EndoR) derivatives, and ER+ BC cells expressing doxycycline (Dox)-inducible ectopic FOXA1 were used in this study. Differential gene expression analysis was performed in EndoR vs. P cells and P cells +Dox vs. -Dox. We found that the FOXA1-CGS was highly enriched in the altered transcriptomes of two ER+ BC cell models (ZR75-1 and T47D) expressing ectopic H-FOXA1. The enriched hallmark gene sets, shared by the H-FOXA1 cell models, include “inflammatory response”, “complement”, and “interferon gamma response” for the H-FOXA1-induced, and “estrogen response early” and “estrogen response late” for the H-FOXA1-repressed genes. These findings point to the common transcriptional profile exhibiting an immune- over estrogen-responsive signature induced by H-FOXA1. In addition, we found that both the tamoxifen-resistant (TamR) and estrogen deprivation-resistant (EDR) derivatives of the 600MPE P cells were enriched for the H-FOXA1-induced CGS and FOXA1/ER-activated Secretome14. Our findings uncover H-FOXA1-induced ER reprogramming driving EndoR and metastasis, possibly via a H-FOXA1/ER-dependent secretome that warrants further studies to clarify its involvement in disease progression of ER+ metastatic BC.
Project description:We report that the winged helix transcription factor FOXA1 is unexpectedly associated with components of single and double stranded-DNA repair complexes. Biochemical studies and high-throughput approaches validated the hierarchical composition of this FOXA1-nucleated machinery and revealed the dependency on FOXA1 for global targeting of the key repair polymerase POLB. Genome-wide DNA methylomes at single-base resolution demonstrated that FOXA1-DNA repair complex is functionally linked to DNA demethylation in a lineage specific fashion. Loss-of-function studies indicate that a significant portion of FOXA1-bound regions display localized reestablishment of methylation and that the subsets with most consistent hypermethylation are represented by active promoters and enhancers that also exhibit the greatest depletion of POLB following FOXA1 removal. Consistently, forced expression of FOXA1 commits its binding sites to an active DNA demethylation in a POLB dependent manner. Finally, we showed that FOXA1-associated DNA demethylation is tightly coupled with genomic targeting of estrogen receptor and estrogen responsiveness. Together, our results link FOXA1-associated DNA demethylation to its transcriptional pioneering.