C10ORF10-DEPP-mediated ROS accumulation is a critical modulator of FOXO3-induced autophagyReportar como inadecuado

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Molecular Cancer

, 16:95

First Online: 25 May 2017Received: 25 November 2016Accepted: 15 May 2017DOI: 10.1186-s12943-017-0661-4

Cite this article as: Salcher, S., Hermann, M., Kiechl-Kohlendorfer, U. et al. Mol Cancer 2017 16: 95. doi:10.1186-s12943-017-0661-4


BackgroundNeuroblastoma is the most common solid tumor in childhood and develops from undifferentiated progenitor cells of the sympathetic nervous system. In neuronal tumor cells DNA-damaging chemotherapeutic agents activate the transcription factor FOXO3 which regulates the formation of reactive oxygen species ROS and cell death as well as a longevity program associated with therapy resistance.

We demonstrated before that C10ORF10-DEPP, a transcriptional target of FOXO3, localizes to peroxisomes and mitochondria and impairs cellular ROS detoxification. In the present study, we investigated the impact of FOXO3 and DEPP on the regulation of autophagy. Autophagy serves to reduce oxidative damage as it triggers a self-degradative process for the removal of aggregated or misfolded proteins and damaged organelles.

MethodsThe effect of FOXO3 and DEPP on autophagy induction was analyzed using live cell fluorescence microscopy and immunoblot analyses of SH-EP cells transfected with a plasmid for EYFP-LC3 and with siRNAs specific for LC3, respectively. ROS steady-state levels were measured with reduced MitoTrackerRed CM-H2XROS. Cellular apoptosis was analyzed by flow cytometry and the caspase 3-7 assay.

ResultsWe report for the first time that DEPP induces ROS accumulation and thereby mediates the formation of autophagosomes as inhibition of ROS formation by N-acetyl-cysteine completely blocks autophagy. We further demonstrate that H2O2-treatment triggers autophagy-induction by FOXO3-mediated DEPP expression. Importantly, knockdown of DEPP was sufficient to efficiently inhibit autophagy-induction under different stress conditions such as serum starvation and genotoxic stress, suggesting that DEPP expression is critical for the initiation of autophagy in neuroblastoma. FOXO3-triggered autophagy partially protects neuroblastoma cells from cell death. Consistent with this concept, we demonstrate that inhibition of autophagy by LC3-knockdown significantly increased etoposide- and doxorubicin-induced apoptosis. These results were also confirmed by the use of the autophagy-inhibitor chloroquine that significantly enhanced the chemotherapeutic effect of etoposide and doxorubicin in neuronal tumor cells.

ConclusionTargeting FOXO3-DEPP-triggered autophagy is a promising strategy to sensitize neuroblastoma cells to chemotherapy.

KeywordsDEPP FOXO3 Autophagy Reactive oxygen species Electronic supplementary materialThe online version of this article doi:10.1186-s12943-017-0661-4 contains supplementary material, which is available to authorized users.

Autor: S. Salcher - M. Hermann - U. Kiechl-Kohlendorfer - M. J. Ausserlechner - P. Obexer

Fuente: https://link.springer.com/

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