Immunolocalizations of human gelatinase (type IV collagenase, MMP-9) and TIMP (tissue inhibitor of metalloproteinases) in normal epidermis and some epidermal tumors.

The matrix metalloproteinases (MMPs) MMP-2 and MMP-9 (gelatinases) have been suggested as serving an important role in cleaving the basement membrane structure. Tissue inhibitors of metalloproteinases TIMPs (particularly TIMP-1) are known to inhibit MMPs. Based on this background, we raised monoclonal antibodies against human gelatinase (MMP-9) and human recombinant TIMP (TIMP-1), and immunostained these two components in skin from patients with squamous cell carcinoma (SCC), Bowen's disease (BD) and keratoacanthoma (KA). MMP-9 showed positive staining mainly in the granular layer of normal epidermis. In some cases of SCC and BD, MMP-9 showed positive staining in the dysplastic lesions even in the basal layer. TIMP showed a thorough positivity in normal epidermis. Unstained regions with this antibody were observed in SCC and BD. These results suggest that an altered staining pattern for MMP-9 and TIMP may be closely related to the malignant transformation of SCC and BD.