angiogenin and arginyl-glycyl-aspartyl-serine

Human angiogenin is an excellent substrate for the adhesion of HT-29 human colon adenocarcinoma cells. These cells adhere more quickly to human angiogenin than to fibronectin, laminin, collagen I, and collagen IV. Anti-angiogenin antibodies and the angiogenesis inhibitors platelet factor-4 and placental ribonuclease inhibitor prevent adhesion of HT-29 cells to angiogenin. Calcium and magnesium ions are not required for adhesion and Arg-Gly-Asp-Ser has no effect, indicating that the interaction is integrin-independent. Instead, adhesion seems to involve a heparan/chondroitin sulfate proteoglycan. Treatment of the cells with heparinase or heparitinase decreases HT-29 cell adhesion onto angiogenin but not onto collagen I. Moreover, cell adhesion is decreased by the presence of heparin or chondroitin sulfates and by preincubation of the cells with inhibitors of proteoglycan synthesis or secretion. In addition, angiogenin binds tightly to heparin-Sepharose, requiring 0.78 M NaCl for elution. Angiogenin-affinity chromatography of a 35S-, 3H-labeled HT-29 cell fraction enriched in cell-surface proteoglycans yields a single, heparinase-sensitive component of apparent molecular mass > 200 kDa, as detected by autoradiography after SDS-polyacrylamide gel electrophoresis. These results suggest that angiogenin could be an effective substrate for tumor cell adhesion during metastasis and may provide a basis for the design of inhibitors of this process.

Topics: Adenocarcinoma; Calcium; Cell Adhesion; Cell Adhesion Molecules; Colonic Neoplasms; Glycosaminoglycans; Humans; In Vitro Techniques; Magnesium; Neovascularization, Pathologic; Oligopeptides; Proteins; Proteoglycans; Ribonuclease, Pancreatic; Tumor Cells, Cultured

When coated on bacteriological plastic at doses greater than or equal to 0.1 microgram/cm2, human and bovine angiogenin support calf pulmonary artery endothelial and Chinese hamster fibroblast cell adhesion and spreading, but do not affect cell adhesion when in solution. The kinetics of endothelial cell attachment to angiogenin are indistinguishable from those in the presence of gelatin. Calcium and/or magnesium ions are critical for cell adhesion or spreading onto angiogenin but protein synthesis and glycoprotein secretion are not necessary. Adhesion to angiogenin is not altered by the addition to the incubation solution of fibronectin, fibrinogen, laminin, collagen I and IV, or vitronectin. The peptide Arg-Gly-Asp-Ser inhibits endothelial cell response to angiogenin whereas the reverse peptide Ser-Asp-Gly-Arg-Gly has no effect. These findings show that angiogenin can serve as an effective substratum for cell adhesion by inducing an interaction similar to but independent from that of other extracellular matrix molecules. Induction of cell adhesion and subsequent migration may be critical steps in the process of angiogenesis.

Topics: Amino Acid Sequence; Angiogenesis Inducing Agents; Animals; Calcium Chloride; Cattle; Cell Adhesion; Cell Line; Dose-Response Relationship, Drug; Endothelium, Vascular; Fibroblasts; Humans; Kinetics; Magnesium Chloride; Molecular Sequence Data; Oligopeptides; Proteins; Pulmonary Artery; Recombinant Proteins; Ribonuclease, Pancreatic