Osteosarcoma (OS) is a primary malignant bone tumor with a high propensity for local recurrence and distant metastasis. We
previously showed a secreted, dominant-negative LRP5 receptor (DNLRP5) suppressed in vitro migration and invasion of the OS
cell line SaOS-2. Therefore, we hypothesized DNLRP5 also has in vivo antitumor activity against OS. We used the 143B cell
line as a model to study the effect of DNLRP5 by stable transfection. Inhibition of Wnt signaling by DNLRP5 was verified by
a reduction in TOPFLASH luciferase activity. In soft agar, DNLRP5-transfected 143B cells formed fewer and smaller colonies
than control transfected cells. DNLRP5 transfection reduced in vivo tumor growth of 143B cells in nude mice. DNLRP5 also decreased
in vitro cellular motility in a scratch wound assay. In a spontaneous pulmonary metastasis model, DNLRP5 reduced both the
size and number of lung metastatic nodules. The reduction in cellular invasiveness by DNLRP5 was associated with decreased
expression of matrix metalloproteinase-2, N-cadherin, and Snail. Our data suggest canonical Wnt/LRP5 signaling reflects an
important underlying mechanism of OS progression. Therefore, strategies to suppress LRP5-mediated signaling in OS cells may
lead to a reduction in local or systemic disease burden.
One or more of the authors has received funding from the Aircast Foundation, the Orthopaedic Research and Education Foundation,
and National Institutes of Health CA116003 (BHH); and the Neil Chamberlain Research Fund and National Institutes of Health
CA109428 (XZ).
Each author certifies that his or her institution has approved the human and animal protocols for this investigation for this
investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed
consent for participation in the study was obtained.