Unknown,Transcriptomics,Genomics,Proteomics

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Drug specific epigenetic reprogramming leads to increased cellular invasion in ERÎ± positive breast cancer via de novo cholesterol biosynthesis.

ABSTRACT: Endocrine therapy resistance remains a critical problem in the treatment of estrogen receptor alpha (ERÎ±) breast cancer. Endocrine therapies target ERÎ± 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.

ORGANISM(S): Homo sapiens

SUBMITTER: Luca Magnani

PROVIDER: E-GEOD-60517 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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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

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Drug specific epigenetic reprogramming leads to increased cellular invasion in ERÎ± positive breast cancer via de novo cholesterol biosynthesis.

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