Detection of cathepsin B in tumor cytosol and urine of breast cancer patients
Dengler, R.; Lah, T.; Gabrijelcic, D.; Turk, V.; Fritz, H.; Emmerich, B.
Biomedica Biochimica Acta 50(4-6): 555-560
1991
ISSN/ISBN: 0232-766X PMID: 1801722 Document Number: 367738
In order to evaluate the role of cathepsin B (CB) as a proteinase involved in mammary tumor progression and its potential role as a tumor marker, we have measured the CB activity in cytosols of breast cancer tumor tissue using Z-Arg-Arg-AMC as the substrate and found a 23fold increase when compared to distantly located breast tissue from the same patient. In addition, urine of breast cancer patients under adjuvant chemotherapy was screened for CB immunoreactivity with a sandwich type enzyme immunoassay which revealed significant interindividual differences in concentrations with some urines containing immunoreactivity comparable to healthy controls. The urines were also investigated for CB activity but no differences between patients and controls were observed. However, urine contains thiol activatable proteinases causing substrate hydrolysis, which is to a varying extent inhibited by E-64 or Z-Phe-Phe-CHN2.