Differences in secretion of the proteinase cathepsin B at the edges of human breast carcinomas and fibroadenomas

TLDR: This study reports here the study of possible differences in the secretion of the lysosomal proteinases, cathepsin D and cat hepsin B, from explants of human tumours, both malignant and non-malignant and from normal breast tissue, as previously suggested.

Abstract: IN 1925 Fischer1 observed that pieces of explanted chicken tumours, unlike normal tissue, caused the lysis of plasma clots. Since then, there have been several investigations into the secretion of degradative enzymes by tumours. An increased extracellular activity of enzymes capable of the destruction of extracellular substances has long been an attractive concept for facilitating the infiltration of normal tissue by tumour cells2–9. Proteinases are natural candidates for study, as extracellular macromolecules and cell surfaces are rich in proteins and glycoproteins. We report here our study of possible differences in the secretion of the lysosomal proteinases, cathepsin D and cathepsin B, from explants of human tumours, both malignant (breast carcinomas) and non-malignant (breast fibroadenomas) and from normal breast tissue, as previously suggested3. Cathepsin B secretion was significantly higher for malignant than non-malignant tissue (fibroadenomas and normal breast tissue). Such a difference in the secretion and extracellular activity of this enzyme might help to explain further the ability of malignant tumours to infiltrate and metastasise.