CATHEPSIN-B, CATHEPSIN-H AND CATHEPSIN-L IN HUMAN BREAST-CARCINOMA

We have measured the activity of the cysteine proteinase cathepsin B, the inhibitory activity of cysteine proteinase inhibitors and the amou nts of cathepsins B, H and L in normal sera and sera from patients wit h breast cancer, as well as in tissue homogenates of tumorous and non- tumorous samples. The amounts of cathepsin B, determined by ELISA in t umour sera (n = 17) were significantly higher than the amounts determi ned in normal sera (n = 20). On the other hand, the differences in the amounts measured in tumour sera were not significant when compared wi th the known histopathological characteristics. In cytosols of breast cancer tumour tissue in general, the level of cathepsin H was higher t han those of cathepsins B and L in all samples tested. In the same sam ples, at least a 10-fold increase of cathepsin B (activity and quantit y) was detected in matched pairs (n = 20) of carcinoma and normal tiss ue of the same breast (p < 0.01). The amount of cathepsin B correlated with the degree of malignancy inside the histological subtypes of inv asive ductal carcinoma (n = 90, p < 0.01). In addition, a negative cor relation of values for cathepsin B with the involvement of regional ly mph nodes (n = 75, p < 0.01) was found inside the same group. In contr ast, the activities of cysteine proteinase inhibitors did not correlat e with any of the known clinical data. Our data provide further indire ct evidence for the involvement of cathepsin B in the processes of tum our growth and metastasis in breast carcinoma. The follow-up studies w ill verify the prognostic value of these findings.