Tumour suppressor EP300, a modulator of paclitaxel resistance and stemness, is down-regulated in metaplastic breast cancer

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Title: Tumour suppressor EP300, a modulator of paclitaxel resistance and stemness, is down-regulated in metaplastic breast cancer
Authors: Yague, E
Asaduzzaman, M
Constantinou, S
Haoxiang, M
Gallon, J
Lin, ML
Singh, P
Raguz, S
Ali, S
Shousha, S
Coombes, RC
Lam, EWF
Hu, Y
Yague, E
Item Type: Journal Article
Abstract: Purpose We have previously described a novel pathway controlling drug resistance, epithelial-to-mesenchymal transition (EMT) and stemness in breast cancer cells. Upstream in the pathway, three miRs (miR-106b, miR-93 and miR-25) target EP300, a transcriptional activator of E-cadherin. Upregulation of these miRs leads to the downregulation of EP300 and E-cadherin with initiation of an EMT. However, miRs regulate the expression of many genes, and the contribution to EMT by miR targets other than EP300 cannot be ruled out. Methods We used lentiviruses expressing EP300-targeting shRNA to downregulate its expression in MCF-7 cells as well as an EP300-knocked-out colon carcinoma cell line. An EP300-expression plasmid was used to upregulate its expression in basal-like CAL51 and MDA-MB-231 breast cancer cells. Drug resistance was determined by short-term proliferation and long-term colony formation assays. Stemness was determined by tumour sphere formation in both soft agar and liquid cultures as well as by the expression of CD44/CD24/ALDH markers. Gene expression microarray analysis was performed in MCF-7 cells lacking EP300. EP300 expression was analysed by immunohistochemistry in 17 samples of metaplastic breast cancer. Results Cells lacking EP300 became more resistant to paclitaxel whereas EP300 overexpression increased their sensitivity to the drug. Expression of cancer stem cell markers, as well as tumour sphere formation, was also increased in EP300-depleted cells, and was diminished in EP300-overexpressing cells. The EP300-regulated gene signature highlighted genes associated with adhesion (CEACAM5), cytoskeletal remodelling (CAPN9), stemness (ABCG2), apoptosis (BCL2) and metastasis (TGFB2). Some genes in this signature were also validated in a previously generated EP300-depleted model of breast cancer using minimally transformed mammary epithelial cells. Importantly, two key genes in apoptosis and stemness, BCL2 and ABCG2, were also upregulated in EP300-knockout colon carcinoma cells and their paclitaxel-resistant derivatives. Immunohistochemical analysis demonstrated that EP300 expression was low in metaplastic breast cancer, a rare, but aggressive form of the disease with poor prognosis that is characterized by morphological and physiological features of EMT. Conclusions EP300 plays a major role in the reprogramming events, leading to a more malignant phenotype with the acquisition of drug resistance and cell plasticity, a characteristic of metaplastic breast cancer.
Issue Date: 24-Mar-2017
Date of Acceptance: 13-Mar-2017
URI: http://hdl.handle.net/10044/1/45608
DOI: https://dx.doi.org/10.1007/s10549-017-4202-z
ISSN: 1573-7217
Publisher: Springer Verlag (Germany)
Start Page: 461
End Page: 474
Journal / Book Title: Breast Cancer Research and Treatment
Volume: 163
Issue: 3
Copyright Statement: © The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Sponsor/Funder: Breast Cancer Now
Funder's Grant Number: 2014NovPhD326
Keywords: ABCG2
Cancer stem cells
Drug resistance
EP300 signature
Oncology & Carcinogenesis
1112 Oncology And Carcinogenesis
Publication Status: Published
Appears in Collections:Division of Surgery
Division of Cancer
Faculty of Medicine

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