CATHEPSIN-B AND CATHEPSIN-D EXPRESSION IN SQUAMOUS-CELL CARCINOMA

To elucidate involvement of proteinases in malignancy of keratinocytes , expression of cathepsin B, a cysteine proteinase, and cathepsin D, a n aspartic proteinase, was ascertained in formalin-fixed paraffin-embe dded specimens of normal skin, squamous cell carcinoma (SCC), Bowen's disease, seborrhoeic keratosis and basal cell carcinoma (BCC). Presenc e of procathepsin B and an intermediate form of cathepsin D was confir med by Western blotting and enzyme activity analysis. Cathepsin B stai ned more intensely in SCC tumour cells than in normal epidermis; stain ing patterns were diffuse, granular or both. Diffuse and granular patt erns (procathepsin B and mature enzyme, respectively) appeared in inne r and outer parts of tumour islands, respectively. Five of 20 cases of Bowen's disease showed diffuse enhanced cathepsin B expression; 20 ca ses of seborrhoeic keratosis or BCC did not. Cathepsin D stained inten sely in tumour cells of half the SCC cases. The staining manner and di stribution of cathepsins B and D was similar in the cytoplasm of cance r cells. No enhanced staining of cathepsin D was seen in any cases of Bowen's disease, seborrhoeic keratosis, or BCC. Coexistence and locali zation of active mature forms of cathepsins B and D suggests that coop eration between the two enzymes may play an important part in invasion of SCC.