The cell surface hyaluronate binding sites of invasive human bladder carcinoma cells

High-affinity, cell surface binding sites for hyaluronate were demonstrated on highly invasive human bladder carcinoma cells. These binding sites were shown to be specific for hyaluronate, saturable and exhibit a Km of 0.94 x 10(-9) M and a Bmax of 65 ng hyaluronate/10(6) cells. The binding of 3H]hyaluronate to a fixed cell-affinity column was competed with unlabeled hyaluronate and hyaluronate-hexasaccharide but not with hyaluronate-tetrasaccharide, chondroitin sulfate, heparin or non-sulfated dextran. Pre-treatment of cells with protease destroyed the binding activity whereas pretreatment with Streptomyces hyaluronidase to reveal occupied binding sites had no effect. No hyaluronate-binding activity was observed on normal human fibroblasts.