Ein neuer Angiogenese-Inhibitor (DBP-maf) inhibiert die Endothelzell-Biologie und das Tumorwachstum im Maus-Model

Abstract

Background: Tumor growth is dependent upon the balance of positive and negative regulators of angiogenesis. At least three antiangiogenic molecules have been previously isolated from conditioned media of tumors where these tumors have shown antiangiogenic potential in a mouse model. Methods and Results: BxPc-3 conditioned media (containing 5% fetal calf serum) was applied to a heparin Sepharose column and eluted with a 0.5 M NaCl steps. Fractions that inhibited capillary endothelial cell proliferation were further purified using Q-Sepharose and monoQ anion exchange chromatography. The inhibitory activity was associated with a protein of 53 kD. Sequence analysis revealed identity to Vitamin D binding protein (DBP). Purified DBP itself had no significant effect on endothelial cell proliferation. Therefore we tested the ability of serum free conditioned media from BxPC3 cells to process DBP by incubating DBP in conditioned media. The converted DBP specifically inhibited endothelial proliferation and was able to stimulate macrophages. Vitamin D binding protein-macrophage activating factor (DBP-maf) was able to suppress tumor growth in a dose dependent manner significantly. Immunhistological analysis showed a significantly reduced micovessel density and a elevated apoptotic rate and an unchanged proliferation rate. Conclusions: Human pancreatic cancer cell line express enzymatic activity which converts DPB to DBP-maf. This molecule inhibits endothelial cell biology in vitro and angiogenesis in vivo and is therefore a new candidate for antiangiogenic tumor therapy.