SCAIF80, a Novel Inhibitor of Angiogenesis, and Its Effect on Tumor Growth.

A novel inhibitor of angiogenesis named SCAIF80 (shark cartilage-derived angiogenesis inhibitory factor) from shark cartilage has been isolated and characterized. SDS-PAGE analysis followed by silver staining revealed a single band with molecular weight (M(r)) of 80 kD. To determine whether this protein was capable of inhibiting angiogensis, it was assayed in endothelial cell (EC) proliferation and migration assay. The results showed that SCAIF80 significantly suppressed EC proliferation and migration in a dose-dependent manner. In the chick chorioallantoic membrane (CAM) assay, SCAIF80 also showed a potent inhibitory activity on angiogenesis in vivo. In animal tests, the growth of tumor was potently suppressed by SCAIF80 therapy. Lewis lung carcinoma was inhibited by 93.83 % at a dose of 5 mg/(kg.d). These findings suggest that shark cartilage may produce a novel protein with anti-angiogenic and anti-tumor activity.

Purification and Functional Characterization of a Shark Cartilage Factor Inhibitory to Angiogenesis.

SCAIF-I, an inhibitor of angiogenesis from shark cartilage was purified to homogeneity. The 4 mol/L guanidinium chloride extract of shark cartilage was fractionally precipitated with 35%-65% acetone, then purified by Resource Q ion exchange chromatography, Sephacryl S-300 gel filtration, and reverse-phase high performance liquid chromatography. The pure inhibitor was homogeneous as a single band on a silver-stained 15% sodium dodecyl sulfate-polyacrylamide gel. SCAIF-I had an molecular weight of 18 kD. It specifically inhibited proliferation of endothelial cells, and strongly blocked endothelial cell movement and angiogenesis in the chorioallantoic membrane of chick embryos. Systemic administration of SCAIF-I at the dose of 5 mg/kg.d suppressed 87.93% of the growth of Lewis lung carcinoma implanted in C57BL/6 mice.