Dataset Information

Pure Estrogen Receptor Antagonists Potentiate Capecitabine Activity in ESR1-mutant Breast Cancer

ABSTRACT: The ESR1 ligand binding domain activating mutations are the most prevalent genetic mechanism of acquired endocrine resistance in metastatic hormone receptor-positive breast cancer. These mutations confer endocrine resistance that remains estrogen receptor (ER) dependent. We hypothesized that in the presence of the ER mutations, continued ER blockade with endocrine therapies that target mutant ER is essential for tumor suppression even with chemotherapy treatment. Here, we conducted comprehensive pre-clinical in vitro and in vivo experiments testing the efficacy of adding fulvestrant to fluorouracil (5FU) and the 5FU pro-drug, capecitabine, in models of wild-type (WT) and mutant ER. Our findings revealed that while this combination had an additive effect in the presence of WT-ER, in the presence of the Y537S ER mutation there was synergy. Notably, these effects were not seen with the combination of 5FU and selective estrogen receptor modulators, such as tamoxifen, or in the absence of intact P53. Likewise, in a patient derived xenograft (PDX) harboring a Y537S ER mutation the addition of fulvestrant to capecitabine potentiated tumor suppression. Moreover, multiplex immunofluorescence revealed that this effect was due to decreased cell proliferation in all cells expressing ER and was not dependent on the degree of ER expression. Taken together, these results support the clinical investigation of the combination of ER antagonists with capecitabine in patients with metastatic hormone receptor-positive breast cancer who have experienced progression on endocrine therapy and targeted therapies, particularly in the presence of an ESR1 activating mutation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE266932 | GEO | 2024/06/01

REPOSITORIES: GEO

ACCESS DATA

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

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.

Dataset Information

Pure Estrogen Receptor Antagonists Potentiate Capecitabine Activity in ESR1-mutant Breast Cancer

Dataset's files

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets