Background: 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.
Objectives: 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.
Methods: 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.
Results: 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).
Conclusions: 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.
Keywords: Breast cancer; cathepsins; cysteine peptidases-like activity; serum biomarkers.