To identify molecular therapeutic targets for
glioma, we performed gene expression profiling by using a
complementary DNA (
cDNA) microarray method and identified the
urokinase plasminogen activator receptor-associated
protein (uPARAP/
Endo180) as a gene expressed highly in
glioma tissue compared with the normal brain tissue. The uPARAP is an endocytic receptor for
collagen. In certain cell types, uPARAP occurs in a complex with the
urokinase plasminogen activator receptor (uPAR) where it fulfills other functions in addition to collagenolysis. Quantitative PCR analysis using a
cDNA panel revealed higher expression levels of uPARAP in
glioma tissue compared with normal brain tissue. Western blot analysis revealed that the uPARAP
protein was expressed in
glioma samples and two
glioma cell lines, KNS42 and KNS81, but not expressed in control tissue from the normal brain. Introduction of
small interfering RNA-targeted uPARAP into the two different
glioma cell lines, KNS42 and KNS81, resulted in downregulation of uPARAP expression, and it significantly suppressed
glioma cell migration and invasion in vitro. Control
glioma cells showed small cell bodies, whereas uPARAP
siRNA-treated
glioma cells exhibited large and flat morphology. Most of the polymeric actin in the control
glioma cells was concentrated in the lamellipodia that are observed in mobile cells. In contrast, in the uPARAP
siRNA-treated
glioma cells, polymeric actin became organized in stress fibers and the lamellipodia disappeared, characteristic of immobile cells. Our present study suggests that uPARAP may be involved in
glioma cell invasiveness through actin cytoskeletal rearrangement. downregulation of uPARAP may be a novel anti-invasion therapeutic strategy for
malignant gliomas.