Chemical factors in the mutual adhesiveness of epithelial cells.

A method has recently been described for measuring the mutual adhesiveness of epithelial cells (3). It was found that cells of squamous cell carcinomas adhered to each other less strongly than did homologous normal epithelial cells. As the cause of this reduction in adhesiveness is not known, it seemed important to seek for an explanation of adhesiveness in normal cclls, and to learn what changes would reduce their adhesiveness. If similar changes should be found in cancers, the reduced adhesiveness of their cells might be explained. Until now, most of the work on cell adhesiveness has been limited to lower forms of animal life, and has been largely qualitative. In such studies it has been shown that calcium is essential for stability of the intercellular matrix (1). In calcium-free solution, blastolneres of marine eggs separate (8,12,13), and restoration of calcium to the fluid medium does not restore their adhesiveness (4). Adhesiveness of larval cells of sponges becomes reduced in calcium-free solution (11), and the 1host complete coalescence of dissociated sponge cells occurs only in the presence of calcium, magnesium and at least one univalent cation, sodimn or potassium (5). The same cations maintain stability of the intercellular matrix in the gill cells of the mussel, Mytilus edulis (6); alkalies facilitate separation of these cells. Thus, in various lower forlns of animal life, calcium and magnesium are important ill maintaining adhesiveness of cells (14). In view of investigations such as those cited above, cxpcrilncnts were designed to determine the cffcct of calcimn and magnesium on adhesiveness of human epithelial cells. If lack of calcium lessened adhesiveness, the decreased adhesiveness observed in cancer might thereby be explained since cancer cells have bccn reported (2) to be deficient in calcium.