[Digestion in vitro of basal membrane, bovine lens capsule, by human liver lysosome cathepsins B, H and L and ascitic fluid tumor cathepsin B from ovarian adenocarcinoma].

Lysosomal cysteine proteinases, cathepsins B, H and L, and tumor cathepsin-B-like protease, are capable of digesting bovine lens capsule, a typical basement membrane, in vitro. Cathepsins L and H proved most active in the pH range 5.0-7.0, whereas cathepsin B and cathepsin B-like protease showed greatest activity at pH 3.0. The process was slow and involved binding of the proteases to the basement membrane. These proteases, of which some are produced by malignant cells, may contribute to tumor spread and progression to metastatic disease.