Cysteine peptidases and their inhibitors in breast and genital cancer

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

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.

Cystatin D locates in the nucleus at sites of active transcription and modulates gene and protein expression

Cystatin D is an inhibitor of lysosomal and secreted cysteine proteases. Strikingly, cystatin D has been found to inhibit proliferation, migration, and invasion of colon carcinoma cells indicating tumor suppressor activity that is unrelated to protease inhibition. Here, we demonstrate that a proportion of cystatin D locates within the cell nucleus at specific transcriptionally active chromatin sites. Consistently, transcriptomic analysis show that cystatin D alters gene expression, including that of genes encoding transcription factors such as RUNX1, RUNX2, and MEF2C in HCT116 cells. In concordance with transcriptomic data, quantitative proteomic analysis identified 292 proteins differentially expressed in cystatin D-expressing cells involved in cell adhesion, cytoskeleton, and RNA synthesis and processing. Furthermore, using cytokine arrays we found that cystatin D reduces the secretion of several protumor cytokines such as fibroblast growth factor-4, CX3CL1/fractalkine, neurotrophin 4 oncostatin-M, pulmonary and activation-regulated chemokine/CCL18, and transforming growth factor B3. These results support an unanticipated role of cystatin D in the cell nucleus, controlling the transcription of specific genes involved in crucial cellular functions, which may mediate its protective action in colon cancer.