Wnt/Frizzled signaling in Ewing sarcoma.
BACKGROUND
The Ewing sarcoma family of tumors (ESFT) is a set of neuroectodermal malignancies that typically presents in the second decade and has a poor prognosis due to metastatic disease. Wnt signaling has a critical role in the normal development of multiple neuroectodermal tissues and also contributes to the neoplastic properties of tumor cells of neuroectodermal origin.


METHODS
We surveyed the expression of Wnts and their receptors in nine ESFT cell lines by RT-PCR analysis. We also tested biological response of ESFT cell lines to exogenous Wnts in beta-catenin stabilization, actin stress fiber formation, and chemotaxis assays.


RESULTS
We detected Wnt-10b in all the lines, and most also expressed Wnt-5a, Wnt-11, and Wnt-13. Several Frizzleds (Fz) and the Wnt co-receptors, low density lipoprotein-receptor-like proteins 5 and 6 were also expressed. We observed a marked stimulation of the beta-catenin/canonical Wnt pathway in ESFT cells treated with Wnt-3a. Wnt-3a induced morphologic changes characterized by the formation of long cytoplasmic extensions in ESFT cells. We also observed chemotaxis of ESFT cells in response to Wnt-3a.


CONCLUSIONS
These results provide evidence that components of Wnt/Fz pathway are expressed and an intact Wnt/Frizzled signaling pathway exists in ESFT cell lines. Activation of the Wnt pathway in ESFT suggests that Wnt modulates cell motility rather than cell proliferation. Hence, activation of this pathway may influence metastatic potential of ESFT.
Uren
Aykut
A
Georgetown University Medical Center, Lombardi Cancer Center, Research Building, Washington, DC 20057-1469, USA. au26@georgetown.edu
Wolf
Vladimir
V
Sun
Yu-Feng
YF
Azari
Amir
A
Rubin
Jeffrey S
JS
Toretsky
Jeffrey A
JA
D045744:Cell Line, Tumor; D048429:Cell Size / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D003598:Cytoskeletal Proteins / Q000378:metabolism; D051157:Frizzled Receptors; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012512:Sarcoma, Ewing / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators / Q000378:metabolism; D051153:Wnt Proteins; D051176:beta Catenin
C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D051157:Frizzled Receptors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D051153:Wnt Proteins; D051176:beta Catenin