The role of cathepsin B and cystatin C in the mechanisms of invasion by ovarian cancer.

OBJECTIVE

The aim of this study was to investigate the contribution of cathepsin B and cystatin C to the mechanisms of invasion by ovarian cancer.

MATERIALS AND METHODS

Using surgical materials from patients with ovarian cancer, immunohistochemistry, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting analysis were performed using antibodies against cathepsin B or cystatin C. Serum levels of cathepsin B and cystatin C in patients with benign and malignant ovarian lesions were determined by enzyme-linked immunosorbent assay (ELISA). An invasion assay using an ovarian cancer cell line was performed by addition of cystatin C or specific inhibitors of cathepsin B.

RESULTS

While immunohistochemical staining of cathepsin B and cystatin C was evident in cancer cells and associated stromal tissue, this was not the case in benign tumors. The malignancies were also found to be positive for cathepsin B and cystatin C by SDS-PAGE and Western blotting analysis. No significant difference in serum cathepsin B levels was observed between patients with benign and malignant disease. However, the concentration of cystatin C in cases with ovarian cancer was significantly higher in benign cases (P<0.0001) and in healthy controls (P<0.0001). Invasion by cancer cells was dose-dependently suppressed by cystatin C and cathepsin B inhibitors.

CONCLUSION

The results provided convincing evidence that cathepsin B and cystatin C may contribute to the mechanisms of invasion of ovarian cancer.