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Project description:Three-dimensional (3D) epigenome remodeling is an important mechanism of gene deregulation in cancer. However, its potential as a target to counteract therapy resistance remains largely unaddressed. Here, we show that epigenetic therapy with decitabine (5-Aza-mC) suppresses tumor growth in xenograft models of pre-clinical metastatic estrogen receptor positive (ER+) breast tumor. Decitabine-induced genome-wide DNA hypomethylation results in large-scale 3D epigenome deregulation, including de-compaction of higher-order chromatin structure and loss of boundary insulation of topologically associated domains. Significant DNA hypomethylation associates with ectopic activation of ER-enhancers, gain in ER binding, creation of new 3D enhancer-promoter interactions and concordant up-regulation of ER-mediated transcription pathways. Importantly, long-term withdrawal of epigenetic therapy partially restores methylation at ER-enhancer elements, resulting in a loss of ectopic 3D enhancer-promoter interactions and associated gene repression. Our study illustrates the potential of epigenetic therapy to target ER+ endocrine-resistant breast cancer by DNA methylation-dependent rewiring of 3D chromatin interactions, which are associated with the suppression of tumor growth.
| S-EPMC10948365 | biostudies-literature
Project description:Here we investigate the impact of epigenetic therapy with Decitabine in endocrine-resistant ER+ breast cancer by using patient-derived xenograft (PDX) models. Decitabine treatment restrained tumour growth, inhibited cell proliferation and resulted in significant loss of DNA methylation, particularly at enhancers and repetitive elements. Systematic integration of matched in situ Hi-C / PCHi-C, EPIC, RNA-seq and ChIP–seq datasets revealed widespread differences in epigenome regulation and enhancer-promoter communication with Decitabine. We find that loss of DNA methylation with Decitabine strongly affects the open (A) and closed (B) compartment structure and TAD boundary insulation. Our study identified and focused on key DNA methylation-dependent, enhancer ER binding sites that are activated in Decitabine-treated PDX tumours, enabling direct interactions between promoters and multiple distal enhancers, inducing expression of ER target genes and pathways. Overall, we demonstrate that epigenetic therapy inhibits tumour progression through to rewiring of ER-mediated 3D chromatin interactions and transcriptome programs. Our findings suggest that targeting the 3D epigenome with epigenetic therapies represents a promising strategy for anti-cancer treatment in ER+ endocrine resistant breast cancer patients.
2023-07-24 | GSE237768 | GEO
Project description:Here we investigate the impact of epigenetic therapy with Decitabine in endocrine-resistant ER+ breast cancer by using patient-derived xenograft (PDX) models. Decitabine treatment restrained tumour growth, inhibited cell proliferation and resulted in significant loss of DNA methylation, particularly at enhancers and repetitive elements. Systematic integration of matched in situ Hi-C / PCHi-C, EPIC, RNA-seq and ChIP–seq datasets revealed widespread differences in epigenome regulation and enhancer-promoter communication with Decitabine. We find that loss of DNA methylation with Decitabine strongly affects the open (A) and closed (B) compartment structure and TAD boundary insulation. Our study identified and focused on key DNA methylation-dependent, enhancer ER binding sites that are activated in Decitabine-treated PDX tumours, enabling direct interactions between promoters and multiple distal enhancers, inducing expression of ER target genes and pathways. Overall, we demonstrate that epigenetic therapy inhibits tumour progression through to rewiring of ER-mediated 3D chromatin interactions and transcriptome programs. Our findings suggest that targeting the 3D epigenome with epigenetic therapies represents a promising strategy for anti-cancer treatment in ER+ endocrine resistant breast cancer patients.
2023-07-24 | GSE237769 | GEO
Project description:The potential of epigenetic therapy to target the 3D epigenome in endocrine-resistant breast cancer
| PRJNA718298 | ENA
Project description:Epigenetic therapy targets the 3D epigenome in endocrine-resistant breast cancer [WGBS]
| PRJNA996580 | ENA
Project description:Epigenetic therapy targets the 3D epigenome in endocrine-resistant breast cancer [CUT&RUN]
| PRJNA996581 | ENA
Project description:Abstract Several endocrine therapy (ET) resistance mechanisms for ER-positive (ER+) breast cancer (BC) have been proposed, including acquired ESR1 (ERα gene) mutations. The two most common ESR1 mutations are Y537S and D538G, which give rise to a constitutively active receptor with reduced affinity for agonists and antagonists. The discovery of new effective therapies remains a significant challenge in treating mutated ER+ BC. In this context, Poly (ADP-ribose) polymerase-1 (PARP-1) has captured considerable interest as a target for therapeutic inhibitors in specific types of cancers. Here, we report that crosstalk between PARP-1 and ERα may represent a novel therapeutic approach for ER+ BC. We have demonstrated that the up-regulation of PARP-1 expression, stimulated by 17-β estradiol (E2), was blocked by treatment with fulvestrant (Ful), a potent ERα antagonist, or ESR1 siRNA in ER+ MCF7 and T47D BC cell models that express both wild type ERα and the Y537S mutation, indicating that ERα regulates the expression of PARP-1. In addition, ERα-mediated transcriptional activity depended on PARP-1 activity in these models, as confirmed by ERα target gene expression and ERE reporter gene analyses +/- niraparib (Nira). Notably, PARP-1 modulates the estrogen-dependent genomic binding of ERα and FoxA1, which play a crucial role in the proliferation of ER+ BC. We also showed that PARP-1 inhibition prevented proliferation and cell cycle activities of ERα WT and ERα Y537S cells upon ERα activation. In vivo, Nira and lasofoxifene (Laso), an ERα antagonist, significantly reduced primary tumor growth versus vehicle, both as single agents and in combination. Moreover, RNA-seq analyses demonstrated the downregulation of ERα signaling in the mammary glands of mice treated with Nira versus Vehicle. Our results provide novel insights into the molecular events through which PARP-1 may serve as a more comprehensive therapeutic approach to target ET BC resistance in women with advanced ER+ BC.
2024-09-30 | GSE277883 | GEO
Project description:Endocrine therapy resistance frequently develops in estrogen receptor positive (ER+) breast cancer, but the underlying molecular mechanisms are largely unknown. Here, we show that 3-dimensional (3D) chromatin interactions both within and between topologically associating domains (TADs) frequently change in ER+ endocrine-resistant breast cancer cells and that the differential interactions are enriched for resistance-associated genetic variants at CTCF-bound anchors. Ectopic chromatin interactions are preferentially enriched at active enhancers and promoters and ER binding sites, and are associated with altered expression of ER-regulated genes, consistent with dynamic remodelling of ER pathways accompanying the development of endocrine resistance. We observe that loss of 3D chromatin interactions often occurs coincidently with hypermethylation and loss of ER binding. Alterations in active A and inactive B chromosomal compartments are also associated with decreased ER binding and atypical interactions and gene expression. Together, our results suggest that 3D epigenome remodelling is a key mechanism underlying endocrine resistance in ER+ breast cancer.
| S-EPMC6965612 | biostudies-literature
Project description:Resistance to aromatase inhibitors (AIs) is a major clinical problem in the treatment of estrogen receptor (ER)-positive breast cancer. In two breast cancer cell line models of AI resistance, we identified widespread DNA hyper- and hypomethylation, with enrichment for promoter hypermethylation of developmental genes. For the homeobox gene HOXC10, methylation occurred in a CpG shore, which overlapped with a functional ER binding site, causing repression of HOXC10 expression. Although short-term blockade of ER signaling caused relief of HOXC10 repression in both cell lines and breast tumors, it also resulted in concurrent recruitment of EZH2 and increased H3K27me3, ultimately transitioning to increased DNA methylation and silencing of HOXC10. Reduced HOXC10 in vitro and in xenografts resulted in decreased apoptosis and caused antiestrogen resistance. Supporting this, we used paired primary and metastatic breast cancer specimens to show that HOXC10 was reduced in tumors that recurred during AI treatment. We propose a model in which estrogen represses apoptotic and growth-inhibitory genes such as HOXC10, contributing to tumor survival, whereas AIs induce these genes to cause apoptosis and therapeutic benefit, but long-term AI treatment results in permanent repression of these genes via methylation and confers resistance. Therapies aimed at inhibiting AI-induced histone and DNA methylation may be beneficial in blocking or delaying AI resistance.
| S-EPMC4277862 | biostudies-literature
Project description:Despite the effectiveness of endocrine therapies in estrogen receptor positive (ER+) breast cancer, approximately 40% of patients relapse. Previously, we identified the Focal-adhesion kinase canonical pathway as a major contributor of resistance to estrogen deprivation and cellular-sarcoma kinase (c-src) as a dominant gene in this pathway. Dasatinib, a pan-src inhibitor, has recently been used in clinical trials to treat ER+ patients but has shown mixed success. In the following study, using isogenic cell line models, we provide a potential explanation for these findings and suggest a sub-group that may benefit. A panel of isogenic cell lines modelling resistance to aromatase inhibitors (LTED) and tamoxifen (TAMR) were assessed for response to dasatinib ± endocrine therapy. Dasatinib caused a dose-dependent decrease in proliferation in MCF7-TAMR cells and resensitized them to tamoxifen and fulvestrant but not in HCC1428-TAMR. In contrast, in estrogen-deprived conditions, dasatinib increased the proliferation rate of parental-MCF7 cells and had no effect on MCF7-LTED or HCC1428-LTED. Treatment with dasatinib caused a decrease in src-phosphorylation and inhibition of downstream pathways, including AKT and ERK1/2 in all cell lines tested, but only the MCF7-TAMR showed a concomitant decrease in markers of cell cycle progression. Inhibition of src also caused a significant decrease in cell migration in both MCF7-LTED and MCF7-TAMR cells. Finally, we showed that, in MCF7-TAMR cells, in contrast to tamoxifen sensitive cell lines, ER is expressed throughout the cell rather than being restricted to the nucleus and that treatment with dasatinib resulted in nuclear shuttling of ER, which was associated with an increase in ER-mediated transcription. These data suggest that src has differential effects in endocrine-resistant cell lines, particularly in tamoxifen resistant models, with low ER genomic activity, providing further evidence of the importance of patient selection for clinical trials testing dasatinib utility in ER+ breast cancer.
| S-EPMC4911087 | biostudies-literature