PROTEIN-KINASE-C ISOTYPES REQUIRED FOR PHORBOL-ESTER INDUCTION OF STROMELYSIN-1 IN RAT FIBROBLASTS

The phorbol-ester tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) is a potent inducer of the metalloproteinase stromelysin in fibr oblasts in vivo and in several cultured cell lines. Rat-1 and Rat-2 fi broblasts, however, do not respond to TPA stimulation by induction of stromelysin gene activity, although collagenase promoter-mediated acti vity is induced threefold by TPA treatment in these cells. We determin ed that rat fibroblasts expressed protein kinase C (PKC) alpha, PKC de lta, PKC epsilon, and PKC zeta but neither the mRNA nor the protein fo r PKC beta. When Rat-2 fibroblasts were stably transfected with an exp ression vector producing PKC beta, however, TPA treatment of these var iants resulted in a 3.1-fold induction of stromelysin promoter-mediate d luciferase activity compared with a 1.3-fold induction in parental R at-2 cells (P < 0.002). Transient transfection of PKC epsilon produced a small but significant increase in TPA-stimulation of both stromelys in- and collagenase-mediated gene expression. These results suggest th at there are PKC isotype-specific signaling pathways that can differen tially regulate matrix metalloproteinase gene expression. (C) 1996 Wil ey-Liss, Inc.