The aim of this study was to identify aberrantly expressed
proteins in pediatric
primitive neuroectodermal tumors (
PNETs) and
ependymomas.
Tumor tissue of 29
PNET and 12
ependymoma patients was subjected to 2-dimensional difference gel electrophoresis. Gel analysis resulted in 79
protein spots being differentially expressed between
PNETs and
ependymomas (p < 0.01, fold change difference in expression >2). Three
proteins,
stathmin,
annexin A1, and calcyphosine, were chosen for validation by immunohistochemistry.
Stathmin was expressed 2.6-fold higher in
PNETs than in
ependymomas, and
annexin A1 and calcyphosine were expressed 2.5- and 37.6-fold higher, respectively, in
ependymomas. All
PNETs showed strong staining for
stathmin, and all
ependymomas were strongly positive for
annexin A1, whereas control tissues were negative. Calcyphosine immunoreactivity was observed in 59% of the
ependymomas and was most profound in
ependymoma tissue showing epithelial differentiation.
mRNA expression levels of
stathmin,
annexin A1, and calcyphosine significantly correlated (Rs = 0.65 [p < 0.0001], Rs = 0.50 [p = 0.001], and Rs = 0.72 [p < 0.0001], respectively) with
protein expression levels. In conclusion, using a
proteome-wide approach,
stathmin,
annexin A1, and calcyphosine were successfully identified as
tumor-specific
proteins in pediatric
PNETs and
ependymomas. Ongoing studies are focused on characterizing the role of these
proteins as
tumor markers and potential drug targets in pediatric
brain tumors.