Calcium influx modulates expression of matrix metalloproteinase-2 (72-kDa type IV collagenase, gelatinase A).

Abstract

Altered regulation of metalloproteinases may play a role in a variety of pathologic conditions including cancer. Previous studies have demonstrated transforming growth factor-beta 1 (TGF-beta 1)-mediated stimulation of expression and activation, and phorbol ester-mediated inhibition of matrix metalloproteinase (MMP)-2 (72-kDa type IV collagenase/gelatinase A), indicating a role for transmembrane signal transduction in MMP-2 regulation. We now describe a role for calcium mobilization in the regulation of MMP-2 expression. Receptor-operated calcium influx has been shown to be inhibited by a novel synthetic inhibitor, carboxy amido-triazole (CAI). Incubation of A2058 human melanoma, HT-1080 human fibrosarcoma, and OVCAR3 human ovarian cancer cells with CAI (0-10 microM) resulted in a dose-dependent reduction in MMP-2 latent and activated species activity by zymogram analysis of conditioned medium. This reduction is not due to direct inhibition of the enzyme by CAI or CAI-induced MMP-2 degradation. Decreased quantity of secreted MMP-2 protein in CAI-treated cells was shown by immunoblot and pulse-chase analysis of newly synthesized MMP-2. Cell coincubation with CAI (2 microM) and TGF-beta 1 (5 ng/ml) caused a decrease in the overall amount of latent and activated MMP-2 by zymogram and immunoblot analysis and showed that CAI inhibited TGF-beta 1 stimulation of MMP-2 production at the level of RNA expression. This was confirmed by Northern analysis of A2058 cells treated with CAI (2 microM) for 24 and 48 h and demonstrated a 55% reduction in message for MMP-2 and a 61% reduction in message for MMP-1, 54-kDa interstitial collagenase. Specificity for CAI action was demonstrated by equivalent MMP-2 inhibitory activity from analogs of CAI that retained the ability to inhibit calcium influx and by lack of inhibition by exposure to inactive CAI analogs that could not inhibit calcium influx. As an independent verification of specificity, a marked reduction in MMP-2 gelatinase activity by zymogram was shown after treatment of A2058 cells with SK&F 96365, an unrelated inhibitor of receptor-operated calcium influx. These results suggest a role for calcium-mediated signal transduction in the expression of metalloproteinases.