CELL-CELL AND CELL-COLLAGEN INTERACTIONS INFLUENCE GELATINASE PRODUCTION BY HUMAN BREAST-CARCINOMA CELL-LINE 8701-BC

We previously produced evidence that the human mammary-carcinoma cell line 8701-BC expresses several metalloproteinases (MMP-1, -2, -9, and -10) and their tissue inhibitors). In order to obtain a better underst anding of the environmental control over gelatinolytic activities, we have tested the enzyme production of 8701-BC cells, at time intervals after plating on different collagen substrates, i.e., types I, III, IV , V and OF/LB, used as films in culture dishes. Proteinase activities, released in the conditioned culture media, were tested by zymography on SDS-PAGE, and by quantificative analyses, using C-14 carboxymethyla ted transferrin as substrate in a liquid incubation medium. Enzymatic activities varied with time and were inversely related to cell densiti es, with minimum values at cell confluence. The enzymatic activity was positively supported by collagen substrates, with a maximal increase in activity when OF/LB collagen was used. In addition to the known MMP s, we found a proteinase with an M(r) of about 20 kDa, which displayed higher activity at 48 hr after cell plating and gradually decreased w ith cell increment. In contrast to the other MMPs, this proteinase is inhibited by soybean trypsin inhibitor, but it does not display a comp lete identity with trypsin, since it does not digest casein and is not inhibited by other serine proteinase inhibitors. (C) 1995 Wiley-Liss, Inc.