Sequential dosing in chemosensitization : targeting the PI3K/Akt/mTOR pathway in neuroblastoma
- Breaking resistance to chemotherapy is a major goal of combination therapy in many tumors, including advanced neuroblastoma. We recently demonstrated that increased activity of the PI3K/Akt network is associated with poor prognosis, thus providing an ideal target for chemosensitization. Here we show that targeted therapy using the PI3K/mTOR inhibitor NVP-BEZ235 significantly enhances doxorubicin-induced apoptosis in neuroblastoma cells. Importantly, this increase in apoptosis was dependent on scheduling: while pretreatment with the inhibitor reduced doxorubicin-induced apoptosis, the sensitizing effect in co-treatment could further be increased by delayed addition of the inhibitor post chemotherapy. Desensitization for doxorubicin-induced apoptosis seemed to be mediated by a combination of cell cycle-arrest and autophagy induction, whereas sensitization was found to occur at the level of mitochondria within one hour of NVP-BEZ235 posttreatment, leading to a rapid loss of mitochondrial membrane potential with subsequent cytochrome c release and caspase-3 activation. Within the relevant time span we observed marked alterations in a ~30 kDa protein associated with mitochondrial proteins and identified it as VDAC1/Porin protein, an integral part of the mitochondrial permeability transition pore complex. VDAC1 is negatively regulated by the PI3K/Akt pathway via GSK3β and inhibition of GSK3β, which is activated when Akt is blocked, ablated the sensitizing effect of NVP-BEZ235 posttreatment. Our findings show that cancer cells can be sensitized for chemotherapy induced cell death – at least in part – by NVP-BEZ235-mediated modulation of VDAC1. More generally, we show data that suggest that sequential dosing, in particular when multiple inhibitors of a single pathway are used in the optimal sequence, has important implications for the general design of combination therapies involving molecular targeted approaches towards the PI3K/Akt/mTOR signaling network.
Author: | Mike-Andrew WesthoffORCiDGND, Najmeh Faham, Daniela Marx, Lisa Nonnenmacher, Claudia Jennewein, Stefanie EnzenmüllerGND, Patrick Gonzalez, Simone FuldaORCiDGND, Klaus-Michael DebatinORCiDGND |
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URN: | urn:nbn:de:hebis:30:3-328782 |
DOI: | https://doi.org/10.1371/journal.pone.0083128 |
ISSN: | 1932-6203 |
Parent Title (English): | PLoS One |
Publisher: | PLoS |
Place of publication: | Lawrence, Kan. |
Document Type: | Article |
Language: | English |
Date of Publication (online): | 2013/12/31 |
Date of first Publication: | 2013/12/31 |
Publishing Institution: | Universitätsbibliothek Johann Christian Senckenberg |
Release Date: | 2014/01/27 |
Volume: | 8 |
Issue: | (12): e83128 |
Page Number: | 14 |
Note: | Copyright: © 2013 Westhoff et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/ , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
HeBIS-PPN: | 363674365 |
Institutes: | Medizin / Medizin |
Dewey Decimal Classification: | 6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit |
Sammlungen: | Universitätspublikationen |
Licence (German): | Creative Commons - Namensnennung 4.0 |