Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA397578 | ENA |
REPOSITORIES: ENA
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Project description:c-Jun/AP-1 overexpression reprograms ERα signaling related to tamoxifen response in ERα-positive breast cancer [ChIP-seq]
| PRJNA397714 | ENA
Project description:A critical mechanism that has been proposed for transcription regulation by estrogen receptor α (ER) is the tethering of ER to DNA via other transcription factors, such as AP-1. However, genome-wide assessment of the overlap in chromatin binding repertoires of these two transcription factors has not been reported. Here, we show that the AP-1 transcription factor c-Jun interacts with ER and that c-Jun chromatin binding shows extensive overlap with ER binding at the global level. Further, we show that c-Jun overexpression reprograms ER chromatin binding and modulates ER-mediated gene regulation. Our data are consistent with a mechanism where estrogen/ER-dependent crosstalk with AP-1 at the transcriptional level is mediated through the tethering of ER to DNA bound AP-1. Additionally, in our system c-Jun overexpression causes reduced sensitivity to tamoxifen in ER+ breast cancer cells. Integrated cistrome, transcriptome, and clinical data reveal TGFBI as a candidate gene which may confer tamoxifen resistance by ER and AP-1 crosstalk. Further, we show that TGFBI expression is elevated in breast cancer compared to normal breast. Together, our data provide a novel genome-wide footprint of ER and AP-1 crosstalk and suggest AP-1 and TGFBI signaling as potential therapeutic targets in AP-1-overexpressing ER-positive breast tumors.
2018-03-02 | GSE102367 | GEO
Project description:Estrogen receptor alpha (ERα) is highly expressed in most breast cancers. Consequently, ERα modulators, such as tamoxifen, are successful in breast cancer treatment, although tamoxifen resistance is commonly observed. While tamoxifen resistance may be caused by altered ERα signaling, the molecular mechanisms regulating ERα signaling and tamoxifen resistance are not entirely clear. Here, we found that PAK4 expression was consistently correlated to poor patient outcome in endocrine treated and tamoxifen-only treated breast cancer patients. Importantly, while PAK4 overexpression promoted tamoxifen resistance in MCF-7 human breast cancer cells, pharmacological treatment with a group II PAK (PAK4, 5, 6) inhibitor, GNE-2861, sensitized tamoxifen resistant MCF-7/LCC2 breast cancer cells to tamoxifen. Mechanistically, we identified a regulatory positive feedback loop, where ERα bound to the PAK4 gene, thereby promoting PAK4 expression, while PAK4 in turn stabilized the ERα protein, activated ERα transcriptional activity and ERα target gene expression. Further, PAK4 phosphorylated ERα-Ser305, a phosphorylation event needed for the PAK4 activation of ERα-dependent transcription. In conclusion, PAK4 may be a suitable target for perturbing ERα signaling and tamoxifen resistance in breast cancer patients.
2015-12-12 | GSE73320 | GEO
Project description:ERα and AP-1 coordinate transcription and tamoxifen response in ERα-positive breast cancer
| PRJNA397705 | ENA
Project description:A critical mechanism for transcription regulation by estrogen receptor α (ER) is the tethering of ER to DNA via other transcription factors, such as AP-1. However, genome-wide assessment of the overlap in chromatin binding repertoires of these two transcription factors has not been reported. Here, we show that the AP-1 transcription factor c-Jun interacts with ER and is recruited globally to ER binding regions. Interestingly, we identify differential motif enrichment between unique ER binding regions and unique c-Jun binding regions, with FoxA1 motif enriched in both sets of binding regions, whereas GATA3 motif only specifically enriched in the unique ER binding regions but not in the unique Jun binding regions. We demonstrate that the primary mechanism for estrogen/ER-dependent transcriptional responses is the tethering of ER to DNA under conditions where it cooperates with AP-1. We provide evidence that c-Jun overexpression causes reduced sensitivity to tamoxifen in ER+ breast cancer cells. Integrated omics data reveal TGFBI as one of the most perturbed genes regulated by c-Jun. TGFBI knockdown suppresses the growth of breast cancer cells and is critical for increasing the sensitivity of tamoxifen-resistant cells to tamoxifen. We show that TGFBI expression is elevated in breast cancer than in normal breast and the basal-like tumors express high levels of TGFBI. TGFBI expression is associated with poor patient survival in ER+ breast cancer receiving endocrine therapy, highlighting a role of AP-1 via TGFBI signaling as a major determinant of endocrine response in ER+ breast tumor.
2018-03-02 | GSE102410 | GEO
Project description:In this study, we probed the importance of OGT activity for the survival of Tamoxifen-sensitive (TamS) and Tamoxifen-resistant (TamR) breast cancer cells. Tamoxifen is an antagonist of estrogen receptor (ERα), a transcription factor expressed in over half of all breast cancers, and the defining characteristic of the ERα-positive disease. ERα-positive breast cancers are successfully treated with Tamoxifen; however, a significant number of patients develops Tamoxifen-resistant disease. We show here that in vitro development of Tamoxifen-resistance results in acquired sensitivity to OGT small molecule inhibitor OSMI-1. Global transcriptome profiling revealed that TamS cells adapt to OSMI-1 treatment by undergoing significant chromatin compaction. In the TamR cells, however, OGT inhibition induces ERRFI1 tumor-suppressor gene expression. ERRFI1 is an endogenous inhibitor of ERBB-signaling, while activation of the ERBB-signaling is one of the best understood mechanism for Tamoxifen-resistance. We show that ERRFI1 is selectively downregulated in ERα-positive breast cancers and breast cancers driven by ERBB2, and provide data to support that this occurs through promoter methylation. Finally, we show that increased ERRFI1 expression is associated with extended survival in patients with ERα-positive tumors (p=9.2e-8). In summary, we show that Tamoxifen-resistance is associated with acquired sensitivity to OSMI-1, and propose that this is explained in part through an epigenetic activation of the tumor-suppressor ERRFI1 in response to OSMI-1 treatment.
2020-10-22 | GSE148186 | GEO
Project description:Estrogen receptor α (ERα) is a key transcriptional regulator in the majority of breast cancers. ERα-positive patients are frequently treated with tamoxifen, but resistance is common. In this study, we refined a previously identified 111-gene outcome prediction-classifier, revealing FEN1 as the strongest determining factor in ERα-positive patient prognostication. FEN1 levels were predictive of outcome in tamoxifen-treated patients, and FEN1 played a causal role in ERα-driven cell growth. FEN1 impacted the transcriptional-activity of ERα by facilitating coactivator recruitment to the ERα transcriptional complex. FEN1 blockade induced proteasome-mediated degradation of activated ERα, resulting in loss of ERα-driven gene expression and eradicated tumor cell proliferation. Finally, a high-throughput 465,195 compound screen identified a novel FEN1 inhibitor, which effectively blocked ERα-function and inhibited proliferation of tamoxifen-resistant cell lines as well as ex-vivo cultured ERα-positive breast tumors. Collectively, these results provide therapeutic proof-of-principle for FEN1 blockade in tamoxifen-resistant breast cancer.
2020-06-01 | GSE95302 | GEO
Project description:Approximately 40% ERα-positive breast cancer patients suffer from therapeutic resistance to tamoxifen. Although reduced ERα level is the major cause of tamoxifen resistance, the underlying mechanisms remain elusive. Here, we report that FRMD8 raises the level of ERα at both transcriptional and post-translational layers. FRMD8 deficiency in MMTV-Cre+; Frmd8fl/fl; PyMT mice accelerates mammary tumor growth and loss of luminal phenotype, and confers tamoxifen resistance. Single-cell RNA profiling reveals that Frmd8 loss decreases the proportion of hormone-sensing differentiated epithelial cells and downregulates the levels of ERα. Mechanically, on one hand, loss of FRMD8 inhibits ESR1 transcription via suppressing the expression of FOXO3A, a transcription factor of ESR1. On the other hand, FRMD8 interacts both with ERα and UBE3A, and disrupts the interaction of UBE3A with ERα, thereby blocking UBE3A-mediated ERα degradation. In breast cancer patients, FRMD8 gene promoter is found hypermethylated and low level of FRMD8 predicts poor prognosis. Therefore, FRMD8 is an important regulator of ERα and may control therapeutic sensitivity to tamoxifen in ERα-positive breast cancer patients.
2025-04-09 | GSE244582 | GEO
Project description:Estrogen and estrogen receptor (ER) signaling play critical roles in the development of ER-positive breast cancer, and endocrine therapy is the frontline treatment for ER-positive breast cancer patients. However, the primary and acquired resistance to endocrine therapy including tamoxifen and fulvestrant remains as the major challenge in the clinic. Here, we identified an estrogen-induced lncRNA, LINC02568, through transcriptomic analysis, which is highly expressed in ER-positive breast cancer. LINC02568 is functional important in ER-positive breast cancer cell growth in vitro and tumorigenesis in vivo as well as endocrine therapy resistance. Mechanically, we demonstrated that LINC02568 regulates, in trans, estrogen/ERα-induced gene transcriptional activation by sponging miR-1233-5p to stabilize ESR1 mRNA in the cytoplasm. Meanwhile, LINC02568 contributes to tumor-specific pH homeostasis in breast cancer cells by regulating CA12 in cis in the nucleus. The dual functions of LINC02568 together contribute to breast cancer cell growth and tumorigenesis as well as endocrine therapy resistance. Antisense oligonucleotides (ASO) targeting LINC02568 significantly inhibits ER-positive breast cancer cell growth in vitro and tumorigenesis in vivo as well as resensitize tamoxifen-resistant cells to tamoxifen. Furthermore, combination treatment with ASO targeting LINC02568 and tamoxifen exhibits synergistic effect on tumor growth. Taken together, our findings revealed dual mechanisms of LINC02568 in regulating ERα signaling and pH homeostasis in ER-positive breast cancer, and indicated that targeting LINC02568 might represent a potential therapeutic avenue in clinic.
2023-09-13 | GSE217190 | GEO
Project description:Rationale: Tamoxifen prevents the recurrence of breast cancer and is also beneficial against bone demineralization and arterial diseases, as it acts as an Estrogen Receptor (ER) α antagonist in ER-positive breast cancers, whereas it mimics the protective action of 17β-estradiol (E2) in other tissues such as arteries. However, the mechanisms of these tissue-specific actions remain unclear. Objective: Here we tested whether tamoxifen is able to accelerate endothelial healing and analyzed the underlying mechanisms. Methods and Results: Using three complementary mouse models of carotid artery injury, we demonstrated that both tamoxifen and estradiol accelerated endothelial healing, but only tamoxifen required the presence of the underlying medial smooth muscle cells. Chronic treatment with E2 and tamoxifen elicited differential gene expression profiles in the carotid artery. The use of transgenic models mouse targeting either whole ERα in a cell-specific manner or ERα subfunctions (membrane/extra-nuclear versus genomic/transcriptional) demonstrated that E2-induced acceleration of endothelial healing is mediated by membrane ERα in endothelial cells, while the effect of tamoxifen is mediated by the nuclear actions of ERα in smooth muscle cells. Conclusion: Whereas tamoxifen acts as an anti-estrogen and ERα antagonist in breast cancer, but also on the membrane ERα of endothelial cells, it accelerates endothelial healing through activation of nuclear ERα in smooth muscle cells, inviting to revisit the mechanisms of action of selective modulation of ERα.
2023-04-12 | GSE154268 | GEO