Determination of cysteine peptidases-like activity and their inhibitors in the serum of patients with ovarian cancer treated by conventional chemotherapy and vitamin E.

Enzymatic activity of cysteine peptidases (cathepsins B and L) --associated with carcinogenesis is controlled by their specific inhibitors. The study was objected to the effects enhanced by taxol and cisplatin in patients pretreated with the vitamin E, by determining the levels of cathepsins B and L in sera of patients with ovarian cancer. The activity of cysteine peptidase (CP) and their inhibitors (CPI) in serum from patients with ovarian cancer and noncancerous patients were measured by using fluorogenic substrate before and after the routine anticancer chemotherapy, and a complementary combination of chemotherapy with vitamin E. The cat B and L activities were significantly higher in patient sera with ovarian cancer than non-cancerous patients (0.0001 pounds sterling). The results shows that, inhibitory activity of CPI and complex form were significantly decreased from 4.6 mEU/mg protein in a group of non-cancerous patients to 0.7 mEU/mg protein in a group of patients with ovarian cancer (p < or = 0.0001). Supplementation with vitamin E after a cycle of therapy with toxic drugs caused a decrease of the cysteine peptidases activities, that is 2.8-fold in patients to whom 40 0mg of vitamin E per day was given in comparison with control, and 6-fold after the third course. The CPI and DCPI complex increased 3-fold and 2.3 fold respectively, as compared to a group of patients were vitamin E was not administered. We observed that vitamin E administered to the patients with ovarian cancer in periods between anticancer drugs therapy courses decreases the cysteine peptidases activity and increases the enzyme-inhibitor complexes level