[Activity of cathepsin D in some neoplasms of the gastrointestinal tract].

In the present paper we analyzed cathepsin D activity in digestive tract cancers. Cathepsin D activity was estimated in 10% homogenates of oesophageal cancer, gastric cancer and colon cancer tissues and in the blood serum and expressed as the amount of liberated tyrosine which was assayed acc. to Folin-Ciocalteau. Mean cathepsin D activities in neoplastic tissues and normal counterparts were as follows: oesophaged cancer (218.5 mM Tyr/1/2 h vs 145.0 mM Tyr/1/2 h), gastric cancer (285.4 mM Tyr/1/2 h vs 142.3 mM Tyr/1/2 h) and colon cancer (233.7 mM Tyr/1/2 h vs 159.5 mM Tyr/1/2 h). In all examined neoplastic tissues cathepsin D activity was almost too-fold higher than in the normal counterparts. Cathepsin D activity in the sera of cancer patients was too a lesser degree higher than in the sera of normal subjects. The data indicate that estimating of cathepsin D activity in the neoplastic tissues homogenates and in the blood serum may be of diagnostic value and may constitute an information which is complementary to the analysis of other tumor markers and histopathologic examination.