Inhibition of cell adhesion by proteolytic fragments of type V collagen.

Type V collagen inhibits the cell-substratum adhesion of many types of cells. In this study, inhibitory effects of type V collagen on the adhesion of mouse melanoma B16-F10 cells to fibronectin, laminin and vitronectin were investigated. When the culture dishes were coated with a mixture of fibronectin and type V collagen, adhesion of the cells was inhibited by 50% at a fibronectin/collagen molar ratio of 10/1. At a similar molar ratio, adhesion of the cells to laminin was inhibited moderately, but that to vitronectin was not significantly affected. Type V collagen added into culture medium was less effective in inhibiting cell adhesion. The antiadhesive activity of type V collagen was partially retained in the alpha 1 (V) chain of heat-denatured collagen. The alpha 1 (V) chain was split into two large fragments, 90 kDa and 60 kDa, by limited digestion with Staphylococcus aureus V8 proteinase. The 90-kDa fragment, which was derived from the C-terminal half of the alpha 1 (V) chain, inhibited the cell adhesion more profoundly than alpha 1 (V). However, little fibronectin bound to the 90-kDa fragment, while fibronectin bound to the 60-kDa fragment, which was less antiadhesive than the 90-kDa fragment, with the same extent as alpha 1 (V). We therefore concluded that the antiadhesive effect of type V collagen was not due to its specific binding to the fibronectin molecule.