Transforming growth factor-beta- and tumor necrosis factor-alpha-mediated induction and proteolytic activation of MMP-9 in human skin

Both cytokines and matrix metalloproteinases (MMPs) are active during physi ologic and pathologic processes such as cancer metastasis and wound repair. We have systematically studied cytokine-mediated MMP regulation. Cytokine- mediated proteinase induction and activation were initially investigated in organ-cultured human skin followed by determination of underlying cellular and molecular mechanisms using isolated skin cells. In this report we demo nstrate that tumor necrosis factor-alpha (TNF-alpha) and transforming growt h factor-beta (TGF-beta) synergistically induce pro-MMP-9 in human skin as well as isolated dermal fibroblasts and epidermal keratinocytes. Furthermor e, TNF-alpha promotes proteolytic activation of pro-MMP-9 by conversion of the 92-kDa pro-MMP-9 to the 82-kDa active enzyme. This activation occurred only in skin organ culture and not by either isolated fibroblasts or kerati nocyte, although the pro-MMP-9 activation could be measured in a cell-free system derived from TNF-alpha -activated skin. The cytokine-mediated induct ion of pro-MMP-9 in dermal fibroblasts was evident by increased mRNA At the transcription level, we examined the cytokine-mediated transactivation of the 5'-region promoter of the human MMP 9 in dermal fibroblasts. The result s demonstrated that TNF-alpha and TGF-beta could independently stimulate th e 5'-flanking 670-base pair promoter. A TGF-beta -response element (-474) a nd an NF-kappaB-binding site (-601) were identified to be the cis-elements for TGF-P or TNF-alpha activation, respectively. Taken together, these find ings suggest a specific mechanism whereby multiple cytokines can regulate M MP-9 expression/activation in the cells of human skin. These results imply roles for these cytokines in the regulation of MMP-9 in physiologic and pat hologic tissue remodeling.