Abstract
The Ewing's sarcoma family of tumours (ESFT) are small round cell tumours characterized by the non-random EWS-ETS gene rearrangements. We have previously demonstrated that ESFT are highly sensitive to fenretinide-induced death, effected in part through a reactive oxygen species (ROS)-dependent pathway. Here, we demonstrate for the first time that the sensitivity of ESFT cells to fenretinide-induced cell death is decreased following downregulation of the oncogenic fusion protein EWS-Fli1; siRNA targeting EWS-Fli1 attenuated fenretinide-induced cell death in cell lines expressing EWS-Fli1, but not EWS-ERG. This decrease in cell death was independent of the level of ROS produced following exposure to fenretinide, but was effected through EWS-Fli1-dependent modulation of p38(MAPK) activity. Furthermore, inhibition of p38(MAPK) activity and knockdown of EWS-Fli1 reduced fenretinide-induced mitochondrial permeabilization, cytochrome c release, caspase and PARP cleavage, consistent with the hypothesis that p38(MAPK) is critical for activation of the death cascade by fenretinide in ESFT cells. These data demonstrate that expression of EWS-Fli1 enhances fenretinide-induced cell death in ESFT and that this is effected at least in part through modulation of p38(MAPK) activity.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Antineoplastic Agents / pharmacology*
-
Apoptosis / drug effects*
-
Blotting, Western
-
Caspases / metabolism
-
Cell Proliferation / drug effects
-
Cytochromes c / metabolism
-
Down-Regulation
-
Electroporation
-
Fenretinide / pharmacology*
-
Flow Cytometry
-
Gene Expression Regulation, Enzymologic*
-
Humans
-
Membrane Potentials / drug effects
-
Mitochondria / drug effects
-
Mitochondria / metabolism
-
Oncogene Proteins, Fusion / antagonists & inhibitors
-
Oncogene Proteins, Fusion / genetics
-
Oncogene Proteins, Fusion / metabolism*
-
Poly(ADP-ribose) Polymerases / metabolism
-
Proto-Oncogene Protein c-fli-1 / antagonists & inhibitors
-
Proto-Oncogene Protein c-fli-1 / genetics
-
Proto-Oncogene Protein c-fli-1 / metabolism*
-
RNA, Small Interfering / pharmacology
-
RNA-Binding Protein EWS
-
Reactive Oxygen Species / metabolism
-
Reverse Transcriptase Polymerase Chain Reaction
-
Sarcoma, Ewing / drug therapy*
-
Sarcoma, Ewing / metabolism
-
Sarcoma, Ewing / pathology
-
Transcription Factors / metabolism
-
Tumor Cells, Cultured
-
p38 Mitogen-Activated Protein Kinases / metabolism*
Substances
-
Antineoplastic Agents
-
EWS-ERG fusion protein, human
-
EWS-FLI fusion protein
-
Oncogene Proteins, Fusion
-
Proto-Oncogene Protein c-fli-1
-
RNA, Small Interfering
-
RNA-Binding Protein EWS
-
Reactive Oxygen Species
-
Transcription Factors
-
Fenretinide
-
Cytochromes c
-
Poly(ADP-ribose) Polymerases
-
p38 Mitogen-Activated Protein Kinases
-
Caspases