ABSTRACT: Expression profile of the endocrine therapy resistant breast cancer cells LTED depleted of PBX1 or treated with the gamma-secretase inhibitor MRK003
Project description:The estrogen receptor alpha (ERa) drives the growth of two-thirds of all breast cancers. Endocrine therapy impinges on estrogen-induced ERa activation to block tumor growth. However, half of ERa-positive breast cancers are tolerant or acquire endocrine therapy resistance. Here we demonstrate that breast cancer cells undergo genome-wide reprogramming of their chromatin landscape, defined by epigenomic maps and chromatin openness, as they acquire resistance to endocrine therapy. This reveals a role for the Notch pathway while excluding classical ERa signaling. In agreement, blocking Notch signaling, using gamma-secretase inhibitors, or targeting its downstream gene PBX1 abrogates growth of endocrine therapy-resistant breast cancer cells. Moreover Notch signaling through PBX1 directs a transcriptional program predictive of tumor outcome and endocrine therapy response. Comparing histone modifications (H3K4me2 and H3K36me3), chromatin openness (FAIRE) and PBX1 binding between endocrine therapy sensitive MCF7 and resistant MCF7-LTED cells.
Project description:Analysis of the response to PBX1 deprivation either using an siRNA approach or using a chemicalcompound indirectly targeting it. Deprivation of PBX1 is hypothesized to be essential for the growth of endocrine therapy resistant breast cancer cells (LTED)
Project description:The estrogen receptor alpha (ERa) drives the growth of two-thirds of all breast cancers. Endocrine therapy impinges on estrogen-induced ERa activation to block tumor growth. However, half of ERa-positive breast cancers are tolerant or acquire endocrine therapy resistance. Here we demonstrate that breast cancer cells undergo genome-wide reprogramming of their chromatin landscape, defined by epigenomic maps and chromatin openness, as they acquire resistance to endocrine therapy. This reveals a role for the Notch pathway while excluding classical ERa signaling. In agreement, blocking Notch signaling, using gamma-secretase inhibitors, or targeting its downstream gene PBX1 abrogates growth of endocrine therapy-resistant breast cancer cells. Moreover Notch signaling through PBX1 directs a transcriptional program predictive of tumor outcome and endocrine therapy response.
Project description:Analysis of the response to PBX1 deprivation either using an siRNA approach or using a chemicalcompound indirectly targeting it. Deprivation of PBX1 is hypothesized to be essential for the growth of endocrine therapy resistant breast cancer cells (LTED) Total RNA was obtained from cells treated with siPBX1 or a control siRNA. The second set contains RNA from cells treated with MRK003 or a control (DMSO).
Project description:A significant fraction of breast cancers exhibit de novo or acquired resistance to estrogen deprivation. To model resistance to aromatase inhibitor (AI) therapy, long-term estrogen-deprived (LTED) derivatives of MCF-7 and HCC-1428 cells were generated through culture for 3 and 7 months under hormone-depleted conditions, respectively. These LTED cells showed sensitivity to the ER downregulator fulvestrant under hormone-depleted conditions, suggesting continued dependence upon ER signaling for hormone-independent growth. To evaluate the role of ER in hormone-independent growth, LTED cells were treated +/- 1 uM fulvestrant x 48 h before RNA was harvested for gene expression analysis.
Project description:Phosphoinositide-3-kinase/protein-kinaseB/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling plays an important role in breast cancer (BC). Its interaction with estrogen receptor (ER) signalling becomes more complex and inter-dependent with acquired endocrine resistance. Targeting mTOR combined with endocrine therapy has shown clinical utility, however, a negative feedback-loop exists downstream of PI3K/AKT/mTOR. Direct blockade of AKT together with endocrine therapy may improve BC treatment. AZD5363, a novel pan-AKT kinase catalytic inhibitor, was examined in a panel of ER+ BC cell lines (MCF7, HCC1428, T47D, ZR75.1) adapted to long-term-estrogen-deprivation (LTED) or tamoxifen (TamR). AZD5363 caused a dose-dependent decrease in proliferation in all cell lines tested (GI50<500nM) except HCC1428 and HCC1428-LTED. T47D-LTED and ZR75-LTED were the most sensitive of the lines (GI50~100nM). AZD5363 re-sensitised TamR cells to tamoxifen and acted synergistically with fulvestrant. AZD5363 decreased p-AKT/mTOR targets leading to a reduction in ERα-mediated transcription in a context specific manner and concomitant decrease in recruitment of ER and CREB-binding protein (CBP) to estrogen-response-elements located on the TFF1, PGR and GREB1 promoters. Furthermore, AZD5363 reduced expression of cell-cycle-regulatory proteins. Global gene expression highlighted ERBB2-ERBB3, ERK5 and IGF1 signaling pathways driven by MYC as potential feedback-loops. Combined treatment with AZD5363 and fulvestrant showed synergy in an ER+ patient derived xenograft and delayed tumour progression post-cessation of therapy. These data support the combination of AZD5363 with fulvestrant as a potential therapy for BC that is sensitive or resistant to E-deprivation or tamoxifen and that activated AKT is a determinant of response, supporting the need for clinical evaluation. Cell lines were treated in biological triplicates in the absence of estrogen with or without AZD5363 for 24hours in order to identify gene changes associated with perturbation of AKT signalling
Project description:To explore the mechanism of endocrine resistance development in estrogen receptor positive breast cancer, transcriptome analysis of MCF-7 and its endocrine resistant derivatives, including tamoxifen resistant (TAMR) sub-lines and long-term estrogen deprivation (LTED) sub-lines, were performed using microarray.
Project description:A significant fraction of breast cancers exhibit de novo or acquired resistance to estrogen deprivation. To model resistance to aromatase inhibitor (AI) therapy, long-term estrogen-deprived (LTED) derivatives of MCF-7 and HCC-1428 cells were generated through culture for 3 and 7 months under hormone-depleted conditions, respectively. These LTED cells showed sensitivity to the ER downregulator fulvestrant under hormone-depleted conditions, suggesting continued dependence upon ER signaling for hormone-independent growth. To evaluate the role of ER in hormone-independent growth, LTED cells were treated +/- 1 uM fulvestrant x 48 h before RNA was harvested for gene expression analysis. MCF-7/LTED and HCC-1428/LTED cells were treated with 10% DCC-FBS with or without the estrogen receptor antagonist drug fulvestrant for 48 hrs prior to RNA harvest for array analysis. Three replicates per condition.
Project description:This randomized phase I/II clinical trial is studying the side effects and best dose of gamma-secretase/notch signalling pathway inhibitor RO4929097 when given together with vismodegib and to see how well they work in treating patients with advanced or metastatic sarcoma. Vismodegib may slow the growth of tumor cells. Gamma-secretase/notch signalling pathway inhibitor RO4929097 may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving vismodegib together with gamma-secretase/notch signalling pathway inhibitor RO4929097 may be an effective treatment for sarcoma.
Project description:Endocrine therapy resistance remains a critical problem in the treatment of estrogen receptor alpha (ERα) breast cancer. Endocrine therapies target ERα via different modes of action. Drug resistance involves drug specific remodeling of the transcriptional and regulatory landscape. Using epigenomics and transcriptomics, we demonstrate that resistance to aromatase inhibitors (AI) induces phenotypical changes through epigenetic activation of cholesterol biosynthesis (CB) and keratin 80. Epigenetic activation is stable and involves both large topological domains and punctuated activation of single enhancers and super-enhancers. Specialized cancer cells expressing high levels of keratin 80 lead invasion through the extracellular matrix. Strikingly, we demonstrate that anti-cholesterol strategies can effectively arrest breast cancer invasion. Our work identifies a robust strategy to target resistant invasive breast cancer. All cell lines were grown in their respective media until they reached 70% confluency. Specifically, MCF7 were grown in DMEM+10% FBS and 1% Pen-Sprep-Glutamine. MCF7T as MCF7 with the addition of 100nM Tamoxifen. MCF7F as MCF7 with the addition of 100nM Fulvestrant. LTED were grown in DMEM without phenol + 10% DCS-FBS and1% Pen-Sprep-Glutamine. LTEDT as LTED with the addition of 100nM Tamoxifen. LTEDF as LTED with the addition of 100nM of Fulvestrant. All chemicals are purchased from Sigma. ChIP-seq was performed using Illumina methodology.
