Calcium-Dependent and-Independent Adhesion of Normal and Transformed BHK Cells

Abstract

The adhesive properties of normal BHK cells and of their transformed derivatives (pyBHK) were studied by examining the aggregation kinetics after different treatments for cell dispersion. Cells dispersed with 0.005 % trypsin with EDTA slowly aggregated only in medium with Ca²⁺. This aggregation was inhibited by cycloheximide. These cells acquired the ability to aggregate in medium without Ca²⁺ after preincubation in medium with Ca²⁺. Cells dispersed with lower trypsin concentrations (below 0.001 %) with EDTA aggregated rapidly in the absence, as well as in the presence of divalent cations. Cells prepared by the above two methods did not require Ca²⁺ for the adhesion process per se (Ca²⁺-independent adhesion), but did require this cation for recovery of adhesiveness damaged by the earlier trypsin treatment. Cells dispersed with 0.005 % trypsin solution containing Ca²⁺ aggregated rapidly in the medium with Ca²⁺, but did not aggregate in medium without Ca²⁺. The aggregation in Ca²⁺ was not inhibited by cycloheximide and required the continuous presence of Ca²⁺ in the assay medium. In this case, the mechanism must have required Ca²⁺ for adhesion per se (Ca²⁺-dependent adhesion). Both the Ca²⁺-independent and-dependent adhesion properties were found also in pyBHK cells, although the degree of Ca²⁺-independent aggregation was less in pyBHK than BHK cells.