Inhibition Of Breast Cancer Metastasis And Angiogenesis By Anti-osteopontin Single Chain Fv-Fc Fusion Protein

Osteopontin (OPN) has been associated with tumor growth and metastasis. In order to study the function of anti-OPN antibodies in inhibiting tumor metastasis, we have raised several anti-OPN single-chain Fv (scFv) antibodies from phage antibody library and expressed them as scFv-Fc fusion proteins. We studied their anti-tumor effects in vitro and in vivo. Two anti-OPN scFv-Fc fusion proteins 1A12 and 2H8 were able to inhibit MDA-MB-435s breast cancer cell attachment, invasion, migration and colony formation in soft agar. 1A12 and 2H8 showed markedly inhibitory effects toward angiogenesis, and this inhibitory effect was achieved by inhibiting NF-kB mediated cell survival pathway and increasing endothelial cell apoptosis. In vivo studies showed 1A12 and 2H8 delayed primary tumor growth and reduced spontaneous lung metastasis in breast cancer xenograft model; furthermore, they reduced tumor microvessel density and increased tumor endothelial cell apoptosis. The present study has demonstrated OPN is an effective target in the treatment of tumor, and anti-OPN scFv-Fc fusion proteins could inhibit tumor metastasis by inhibiting angiogenesis and breast cancer cell migration.