Proteolysis is an intrinsic component of cutaneous wound repair and several matrix metalloproteinases have been shown to participate in various stages of this process. Therefore, we investigated the expression of a novel metalloproteinase, collagenase-3 (MMP-13), in normally healing cutaneous wounds and chronic venous ulcers. MMP-13 was expressed abundantly by fibroblasts deep in the chronic ulcer bed but was not detected in epidermis and all the acute wounds. The spatial expression of MMP-13 differed from that of collagenase-1 (MMP-1), which was prominently expressed by migrating keratinocytes and dermal cells located just beneath the wound surface. Northern blot hybridization did not reveal expression of MMP-13 by fibroblasts cultured on tissue culture plastic. In accordance with our in vivo findings, however, fibroblasts grown in a collagen gel produced MMP-13 mRNA abundantly. Our results suggest that MMP-13 can be induced in skin during wound repair after altered cell-matrix interactions. Although both MMP-1 and MMP-13 have the unique ability to degrade fibrillar collagens, their regulation and role during wound repair seem different. Collagenase-1 is critical for re-epithelialization, and MMP-13 most likely plays a role in the remodeling of collagenous matrix in chronic wounds.

Controlled degradation of extracellular matrix (ECM) is essential for the growth, invasion, and metastasis of malignant tumors, and for tumor-induced angiogenesis. Matrix metalloproteinases (MMPs) are a family of zinc-dependent neutral endopeptidases collectively capable of degrading essentially all ECM components and they apparently play an important role in all these aspects of tumor development. Furthermore, recent evidence suggests that MMPs also play a role in tumor cell survival. In this review, we discuss the current concept concerning the role of MMPs and their inhibitors in tumor invasion, as a basis for prognosis and targeted therapeutic intervention in cancer.

Co-expression of several members of the matrix metalloproteinase (MMP) family is a characteristic of human carcinomas. To investigate the role of the recently cloned collagenase-3 (MMP-13) in epidermal tumors, we studied samples representing malignant (basal and squamous cell carcinoma, Paget's disease), pre-malignant (Bowen's disease, solar keratosis), and benign (keratoacanthoma, seborrheic keratosis, linear epidermal nevus) tumors. Basal cell carcinomas expressed collagenase-3 mRNA in focal areas of keratinized cells, the squamous differentiation of which was confirmed by positive immunostaining for involucrin. Apoptosis was observed in central parts of these foci. In squamous cell carcinomas, collagenase-3 expression was detected at the epithelial tumor front and less frequently in the surrounding stromal cells. Collagenase-3 mRNA co-localized with immunostaining for laminin-5, an adhesion molecule suggested to participate in the migration of tumor cells. The pre-malignant and benign tumors were mostly negative for collagenase-3. Stromelysin-1, a potential activator of latent collagenases, was frequently expressed by stromal cells surrounding the malignant tumors, and the two MMPs occasionally co-localized in keratotic foci. Our results demonstrate that in basal cell carcinomas, expression of collagenase-3 is associated with terminal differentiation of epithelial cells. Furthermore, the gene is activated during skin carcinogenesis, and we suggest a role for collagenase-3 in degradation of the extracellular matrix associated with malignant epithelial growth.