Regulation of Tumor Cell Chemotaxis by Type IV Collagen Is Mediated by a Ca2+-dependent Mechanism Requiring CD47 and the Integrin αVβ3

Studies from our laboratories demonstrated that synthetic peptides from the non-collagenous (NC-1) domain of the α3 (IV) chain of type IV collagen (COL IV) enhanced tumor cell adhesion (Han, J., Ohno, N., Monboisse, J. C., Pasco, S., Borel, J. P., and Kefalides, N. A. (1997) J. Biol. Chem. 272, 20395–20401). We have isolated the receptors for the α3(IV)185–203 peptide from melanoma and prostate tumor cells and identified them as CD47/integrin-associated protein and the integrin αVβ3 (Shahan, T. A., Ziaie, Z., Pasco, S., Fawzi, A., Bellon, G., Monboisse, J. C., and Kefalides, N. A. (1999) Cancer Res. 59, 4584–4590). In the present study we have examined the effect of CD47 and the integrin αVβ3 on in vitro tumor cell chemotaxis and Ca2+imodulation in response to COL IV, from the anterior lens capsule (ALC-COL IV) and peptides from its NC-1 domain. COL IV as well as the α3(IV) peptide promoted tumor cell chemotaxis with an immediate increase in intracellular [Ca2+]. Treating tumor cells with CD47 and integrin αVβ3-reactive antibodies reduced chemotaxis as well as the rise in [Ca2+]i in response to ALC-COL IV or the α3(IV)185–203 peptide but not to Engelbreth-Holm-Swarm-COL IV or fibronectin. The α3(IV)185–203 synthetic peptide stimulated an increase in calcium from intracellular stores exclusively, whereas ALC-COL IV, Engelbreth-Holm-Swarm-COL IV, and fibronectin stimulated Ca2+ flux from both internal and external stores. Furthermore, treatment of the cells with Ca2+ chelator bis-(O-aminophenoxyl)ethane-N,N,N′,N′-tetraaceticacid-acetomethoxy ester inhibited chemotaxis toward both ALC-COL IV and the α3(IV)185–203 peptide. These data indicate that CD47 and integrin αVβ3 regulate tumor cell chemotaxis in response to COL IV and the α3(IV)185–203 peptide through a Ca2+-dependent mechanism.