http://clincancerres.aacrjournals.org/cgi/content/abstract/11/8/3136
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=15837770&dopt=Abstract
Clinical Cancer Research Vol. 11, 3136-3148, April 15, 2005
© 2005 American Association for Cancer Research
Cancer Therapy: Preclinical
p38MAPK-Dependent Sensitivity of Ewing's Sarcoma Family of Tumors to
Fenretinide-Induced Cell Death
Stephen S. Myatt1, Christopher P.F. Redfern2 and Susan A. Burchill1
Authors' Affiliations: 1 Candlelighter's Children's Cancer Research
Laboratory, Cancer Research UK Clinical Centre, Leeds, United Kingdom
and 2 Northern Institute for Cancer Research, University of Newcastle
upon Tyne, Newcastle upon Tyne, United Kingdom
Requests for reprints: Susan A. Burchill, Candlelighter's Children's
Cancer Research Laboratory, Cancer Research UK Clinical Centre, St.
James's University Hospital, Beckett Street, Leeds LS9 7TF, United
Kingdom. Phone: 44-113-2065873; Fax: 44-113-2429886; E-mail:
S.A.Burchill@leeds.ac.uk.
Purpose: There is an urgent need for new therapeutic strategies in
Ewing's sarcoma family of tumors (ESFT). In this study, we have
evaluated the effect of fenretinide [N-(4-hydroxyphenyl)retinamide] in
ESFT models.
Experimental Design: The effect of fenretinide on viable cell number and
apoptosis of ESFT cell lines and spheroids and growth of s.c. ESFT in
nu/nu mice was investigated. The role of the stress-activated kinases
p38MAPK and c-Jun NH2-terminal kinase in fenretinide-induced death was
investigated by Western blot and inhibitor experiments. Accumulation of
reactive oxygen species (ROS) and changes in mitochondrial transmembrane
potential were investigated by flow cytometry.
Results: Fenretinide induced cell death in all ESFT cell lines examined
in a dose- and time-dependent manner. ESFT cells were more sensitive to
fenretinide than the neuroblastoma cell lines examined. Furthermore,
fenretinide induced cell death in ESFT spheroids and delayed s.c. ESFT
growth in mice. p38MAPK was activated within 15 minutes of fenretinide
treatment and was dependent on ROS accumulation. Inhibition of p38MAPK
activity partially rescued fenretinide-mediated cell death in ESFT but
not in SH-SY5Y neuroblastoma cells. c-Jun NH2-terminal kinase was
activated after 4 hours and was dependent on ROS accumulation but not on
activation of p38MAPK. After 8 hours, fenretinide induced mitochondrial
depolarization ({Delta}{psi}m) and release of cytochrome c into the
cytoplasm in a ROS- and p38MAPK-dependent manner.
Conclusions: These data show that the high sensitivity of ESFT cells to
fenretinide is dependent in part on the rapid and sustained activation
of p38MAPK. The efficacy of fenretinide in preclinical models demands
the evaluation of fenretinide as a potential therapeutic agent in ESFT.
Key Words: stress-activated kinases • retinamides • ESFT • neuroblastoma