Receptors for hyaluronate on the surface of parent and virus-transformed cell lines : Binding and aggregation studies

Two sets of parent and virus-transformed cell lines (3T3 vs SV-3T3; BHK vs PY-BHK) were compared with respect to the extent of divalentcation independent aggregation which previously has been shown to depend upon the interaction of endogenous hyaluronate with specific receptors on the cell surface. When measured under conditions of physiological ionic strength, a significant amount of hyaluronidase-inhibitable aggregation was found in the virus-transformed cell lines (SV-3T3 and PY-BHK) but not in their parent counterparts (3T3 and BHK). However, when the same experiment was performed in a high ionic strength solution (0.5 M NaCl), the hyaluronidase inhibitable aggregation was detected in all of the cell lines. The differences in the aggregation between the various cell lines was also reflected in the binding of ³H]hyaluronate. In physiological saline, the virus-transformed cells bound greater amounts of hyaluronate (higher B_max) with a greater affinity (lower k_d) than did their untransformed counterparts. Increasing the ionic strength to 0.5 M NaCl increased the binding of ³H]hyaluronate by each cell line; however, the relative differences between the cell lines remained. These results indicate that variations in the ability of the cells to bind hyaluronate can partially account for the differences between the parent and the virus-transformed cells with respect to their ability to aggregate.