GROWTH FACTOR-INDUCED EPIDERMAL INVASION OF THE DERMIS IN HUMAN SKIN ORGAN-CULTURE - EXPRESSION AND ROLE OF MATRIX METALLOPROTEINASES

Matrix metalloproteinase activity was assessed in culture fluids of or gan-cultured human skin by gelatin zymography. Both the 92-kD gelatina se/type IV collagenase and the 72-kD gelatinase-type IV collagenase we re detected. Production of the 92-kD enzyme was substantially increase d in the presence of epidermal growth factor (EGF) and hepatocyte grow th factor (HGF) as compared to control but not in the presence of insu lin-like growth factor-1 (IGF-1) or keratinocyte growth factor (KGF). This is of interest because our recent studies have shown that EGF and HGF induce the epithelial cells to invade the underlying stroma while normal architecture is maintained in the presence of IGF-1 and KGF. A ddition of tissue inhibitor of metalloproteinase-2 to the organ cultur e fluids blocked expression of the active forms of both enzymes and co ncomitantly blocked invasion. Epidermal keratinocytes, dermal fibrobla sts and dermal endothelial cells were grown in monolayer culture and e xamined for matrix metalloproteinase production. The 92-kD enzyme acco unted for most of the gelatinase activity in keratinocyte culture flui ds while the 72-kD enzyme accounted for most of the activity in the de rmal fibroblast and endothelial cell culture fluids. Increased product ion of the 92-kD enzyme was seen in keratinocytes upon exposure to the growth factors that induced invasion (EGF and HGF) while the two fact ors that did not induce invasion (IGF-1 and KGF) were much less effect ive. Production of the 72-kD enzyme in fibroblasts and endothelial cel ls was not upregulated by any of the four growth factors. Taken togeth er, these data indicate that matrix metalloproteinase activity is incr eased in the epithelium under the influence of invasion-inducing growt h factors and contributes to invasion.