Collagenase activity in rabbit carcinoma: cell source and cell interactions.

Fibroblast-like cells (F-cells) and epithelial-like (E-cells) derived from cultures of rabbit VX-2 carcinoma released collagenase in both active and latent forms in serum-free medium at a level higher than that of normal rabbit fibroblast cultures. The enhanced capacity of the F-cells to release the enzyme, however, continued only for a few passages and then decreased significantly to a low level similar to that of the normal fibroblasts. The enzyme-release by the E-cells continued for a few more passages at a relatively moderate level, higher than that of normal fibroblasts. The release of collagenase in cultures of F-cells was enhanced by the presence of E-cells in mixed cultures as well as by medium conditioned by the E-cells type. Addition of cytochalasin B at 2 micrograms/ml did not significantly effect the enzyme activity released in the cultures. Serum from tumor-bearing rabbits appeared to stimulate the release of enzyme activity in cultures of either cell type.