Differences in cysteine peptidases-like activity in sera of patients with breast cancer.

The key role in carcinogenesis with destruction of the extracellular matrix is played by proteases released by invasive cancer cells. Cysteine peptidases, such as cathepsin B and L, take an important role in cancer progression and metastasis.Cysteine peptidase-like activity (CPA) in sera of patients with breast cancer at different stages of disease and the influence of genetic predisposition associated with BRCA-1 gene mutations were analysed.CPA in serum was determined with the spectrofluorometric technique using Z-Phe-Arg-AMC as a substrate. Determination was carried out in 111 breast cancer patients in comparison to a control group of 50 healthy subjects.The highest CPA was found in breast cancer patients with a hereditary predisposition bearing BRCA1 gene mutations, and the lowest activity was found in patients who had a tumour surgically removed and before adjuvant therapy. The differences in the activities between control group and cancer groups were statistically significant (p< 0.05), except from group of cancer patients in complete remission (p< 0.52).Serum CPA in patients with breast cancer differs depending on the cancer stage and treatment methods. Our study demonstrate the correlation between BRCA-1 gene mutations and the increased level of CPA.