BAG3 overexpression and cytoprotective autophagy mediate apoptosis resistance in chemoresistant breast cancer cells

Target-specific treatment modalities are currently not available for triple-negative breast cancer (TNBC), and acquired chemotherapy resistance is a primary obstacle for the treatment of these tumors. Here we employed de
Target-specific treatment modalities are currently not available for triple-negative breast cancer (TNBC), and acquired chemotherapy resistance is a primary obstacle for the treatment of these tumors. Here we employed derivatives of BT-549 and MDA-MB-468 TNBC cell lines that were adapted to grow in the presence of either 5-Fluorouracil, Doxorubicin or Docetaxel in an aim to identify molecular pathways involved in the adaptation to drug-induced cell killing. All six drug-adapted BT-549 and MDA-MB-468 cell lines displayed cross resistance to chemotherapy and decreased apoptosis sensitivity. Expression of the anti-apoptotic co-chaperone BAG3 was notably enhanced in two thirds (4/6) of the six resistant lines simultaneously with higher expression of HSP70 in comparison to parental controls. Doxorubicin-resistant BT-549 (BT-549rDOX20) and 5-Fluorouracil-resistant MDA-MB-468 (MDA-MB-468r5-FU2000) cells were chosen for further analysis with the autophagy inhibitor Bafilomycin A1 and lentiviral depletion of ATG5, indicating that enhanced cytoprotective autophagy partially contributes to increased drug resistance and cell survival. Stable lentiviral BAG3 depletion was associated with a robust down-regulation of Mcl-1, Bcl-2 and Bcl-xL, restoration of drug-induced apoptosis and reduced cell adhesion in these cells, and these death-sensitizing effects could be mimicked with the BAG3/Hsp70 interaction inhibitor YM-1 and by KRIBB11, a selective transcriptional inhibitor of HSF-1. Furthermore, BAG3 depletion was able to revert the EMT-like transcriptional changes observed in BT-549rDOX20 and MDA-MB-468r5-FU2000 cells. In summary, genetic and pharmacological interference with BAG3 is capable to resensitize TNBC cells to treatment, underscoring its relevance for cell death resistance and as a target to overcome therapy resistance of breast cancer.
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Metadaten
Author:Chandan Kanta Das, Benedikt Linder, Florian Bonn, Florian Rothweiler, Ivan Dikic, Martin Michaelis, Jindrich Cinatl, Mahitosh Mandal, Donat Kögel
URN:urn:nbn:de:hebis:30:3-457787
DOI:http://dx.doi.org/10.1016/j.neo.2018.01.001
ISSN:1476-5586
ISSN:1522-8002
Pubmed Id:http://www.ncbi.nlm.nih.gov/pubmed?term=29462756
Parent Title (English):Neoplasia
Publisher:Stockton Press
Place of publication:Basingstoke
Document Type:Article
Language:English
Year of Completion:2018
Date of first Publication:2018/02/22
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2018/03/01
Volume:20
Issue:3
Pagenumber:17
First Page:263
Last Page:279
Note:
© 2018 The Authors. Published by Elsevier Inc. on behalf of Neoplasia Press, Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
HeBIS PPN:432033912
Institutes:Medizin
Exzellenzcluster Makromolekulare Komplexe
Dewey Decimal Classification:610 Medizin und Gesundheit
Sammlungen:Universitätspublikationen
Open-Access-Publikationsfonds:Medizin
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell - Keine Bearbeitung 4.0

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