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Endocrine response in invasive lobular carcinoma is characterized by unique estrogen-mediated gene expression and de novo tamoxifen resistance (SUM44)

ABSTRACT: Invasive lobular carcinoma (ILC) is a histological subtype of breast cancer that is frequently associated with favorable outcomes, as ~90% of ILC express the estrogen receptor (ER). However, recent retrospective analyses suggest that ILC patients receiving adjuvant endocrine therapy may not benefit from improved outcomes versus other breast cancer patients. Based on these observations, we characterized ER function and endocrine response in ILC models. The ER-positive ILC cell lines MDA MB 134VI (MM134) and SUM44PE were used to examine the ER-regulated transcriptome in vitro via gene expression microarray analyses and ER ChIP-Seq. In parallel, estrogen response was assessed in vivo in the patient-derived ILC xenograft HCI-013. Response to endocrine therapy was also examined in ILC cell lines. We identified 915 genes that were uniquely E2-regulated in ILC cell lines versus other breast cancer cell lines, and a subset of these genes were also regulated in vivo in HCI-013. We observed that MM134 were de novo tamoxifen resistant, and were induced to grow by 4-hydroxytamoxifen, as well as other anti-estrogens, as partial agonists. Growth was accompanied by agonist activity of tamoxifen on ER-mediated gene expression. Though tamoxifen induced cell growth, MM134 cells required FGFR1 signaling to maintain viability and were sensitive to combined endocrine therapy and FGFR1 inhibition. Our observation that ER drives a unique program of gene expression in ILC cells correlates with the ability of tamoxifen to induce growth in these cells. Targeting growth factors using FGFR1 inhibitors may block survival pathways required by ILC and reverse tamoxifen resistance.

ORGANISM(S): Homo sapiens

PROVIDER: GSE50694 | GEO | 2014/01/16

SECONDARY ACCESSION(S): PRJNA218517

REPOSITORIES: GEO

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Project description:Invasive lobular carcinoma (ILC) is a histological subtype of breast cancer that is frequently associated with favorable outcomes, as ~90% of ILC express the estrogen receptor (ER). However, recent retrospective analyses suggest that ILC patients receiving adjuvant endocrine therapy may not benefit from improved outcomes versus other breast cancer patients. Based on these observations, we characterized ER function and endocrine response in ILC models. The ER-positive ILC cell lines MDA MB 134VI (MM134) and SUM44PE were used to examine the ER-regulated transcriptome in vitro via gene expression microarray analyses and ER ChIP-Seq. In parallel, estrogen response was assessed in vivo in the patient-derived ILC xenograft HCI-013. Response to endocrine therapy was also examined in ILC cell lines. We identified 915 genes that were uniquely E2-regulated in ILC cell lines versus other breast cancer cell lines, and a subset of these genes were also regulated in vivo in HCI-013. We observed that MM134 were de novo tamoxifen resistant, and were induced to grow by 4-hydroxytamoxifen, as well as other anti-estrogens, as partial agonists. Growth was accompanied by agonist activity of tamoxifen on ER-mediated gene expression. Though tamoxifen induced cell growth, MM134 cells required FGFR1 signaling to maintain viability and were sensitive to combined endocrine therapy and FGFR1 inhibition. Our observation that ER drives a unique program of gene expression in ILC cells correlates with the ability of tamoxifen to induce growth in these cells. Targeting growth factors using FGFR1 inhibitors may block survival pathways required by ILC and reverse tamoxifen resistance. Cells were hormone deprived by replacing growth medium with IMEM+2% charcoal stripped serum for 3 days. Following deprivation, cells were treated for 3 or 24 hours with 1nM E2 or vehicle (0.01% EtOH) in biological quadruplicate. Following treatment, cells were lysed and RNA was harvested using the Illustra RNAspin Mini kit (GE Health). cRNA synthesis and labeling was performed using the Ambion MessageAmp Premier Kit (Life Technologies), and cRNA was hybridized to U133A 2.0 arrays (Affymetrix, Santa Clara, CA). cRNA synthesis and labeling, hybridization, and scanning were performed by the University of Pittsburgh Cancer Biomarkers Facility.

Project description:Invasive lobular carcinoma (ILC) is a histological subtype of breast cancer that is frequently associated with favorable outcomes, as ~90% of ILC express the estrogen receptor (ER). However, recent retrospective analyses suggest that ILC patients receiving adjuvant endocrine therapy may not benefit from improved outcomes versus other breast cancer patients. Based on these observations, we characterized ER function and endocrine response in ILC models. The ER-positive ILC cell lines MDA MB 134VI (MM134) and SUM44PE were used to examine the ER-regulated transcriptome in vitro via gene expression microarray analyses and ER ChIP-Seq. In parallel, estrogen response was assessed in vivo in the patient-derived ILC xenograft HCI-013. Response to endocrine therapy was also examined in ILC cell lines. We identified 915 genes that were uniquely E2-regulated in ILC cell lines versus other breast cancer cell lines, and a subset of these genes were also regulated in vivo in HCI-013. We observed that MM134 were de novo tamoxifen resistant, and were induced to grow by 4-hydroxytamoxifen, as well as other anti-estrogens, as partial agonists. Growth was accompanied by agonist activity of tamoxifen on ER-mediated gene expression. Though tamoxifen induced cell growth, MM134 cells required FGFR1 signaling to maintain viability and were sensitive to combined endocrine therapy and FGFR1 inhibition. Our observation that ER drives a unique program of gene expression in ILC cells correlates with the ability of tamoxifen to induce growth in these cells. Targeting growth factors using FGFR1 inhibitors may block survival pathways required by ILC and reverse tamoxifen resistance. Cells were hormone deprived by replacing growth medium with IMEM+10% charcoal stripped serum for 3 days. Following deprivation, cells were treated for 3 or 24 hours with 1nM E2 or vehicle (0.01% EtOH) in biological quadruplicate. Following treatment, cells were lysed and RNA was harvested using the Illustra RNAspin Mini kit (GE Health). cRNA synthesis and labeling was performed using the Ambion MessageAmp Premier Kit (Life Technologies), and cRNA was hybridized to U133A 2.0 arrays (Affymetrix, Santa Clara, CA). cRNA synthesis and labeling, hybridization, and scanning were performed by the University of Pittsburgh Cancer Biomarkers Facility.

Project description:Background: Up to 40% of patients with estrogen receptor positive (ER+) breast cancer experience treatment resistance and disease recurrence, often caused by the upregulation of growth factor receptors. Understanding the mechanisms of resistance, and the identification of novel therapeutic targets is, therefore, of vital importance if breast cancer prognosis is to be further improved. Fibroblast growth factor receptor 1 (FGFR1) is a potential driver of endocrine resistance; however, clinically successful attempts at targeting FGFR1 activity in breast cancer are rare and may result from an inability to correctly identify patients that could benefit from such treatment. The identification of additional genes associated with an FGFR1-mediated mechanism of resistance will provide a more precise classification scheme for FGFR1-dependency in breast cancer. Methods: Live cell imaging and RNA sequencing of ER+ breast cancer cell lines (CAMA1, T47D, tamoxifen resistant T47D) were used to investigate FGFR1-dependency in breast cancer, mechanisms of endocrine resistance and the effects of treatment with tamoxifen and erdafitinib. An FGFR1-amplified ER+ breast cancer patient-derived xenograft (PDX) model was used to assess the effects of targeting FGFR1 in vivo. Gene expression analysis of human breast cancer from The Cancer Genome Atlas (TCGA) was used for clinical validation. Results: We evaluated the effects of targeting FGFR1 in ER+/HER2- breast cancer with aberrant FGFR1 amplification and/or overexpression. We found that the FGFR tyrosine kinase inhibitor (TKI) erdafitinib inhibited cell proliferation of FGFR1-amplified CAMA1 cells in vitro. Additionally, erdafitinib significantly enhanced the anti-proliferative effect of 4-hydroxytamoxifen (4-OHT) and its anti-tumor effect was also demonstrated in vivo. Further, we demonstrated that the proliferation of FGFR1-overexpressing tamoxifen-resistant T47D (TR-T47D) cells is dependent on FGFR1 activity. Moreover, these TR-T47D cells are re-sensitized to tamoxifen upon treatment with erdafitinib. Finally, we found that upregulation of genes related to epithelial-mesenchymal-transition (EMT) correlates with FGFR1 overexpression, and is reversed by FGFR inhibition. Conclusions: In this study we demonstrated that targeting FGFR1 in ER+/HER2- breast cancer with aberrant FGFR1 activity has the potential to inhibit tumor growth and to re-sensitize resistant tumors to tamoxifen. Furthermore, we identified a functional relationship between EMT, FGFR activity and endocrine resistance in breast tumorigenesis.

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Endocrine response in invasive lobular carcinoma is characterized by unique estrogen-mediated gene expression and de novo tamoxifen resistance (SUM44)

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