Assessment of cathepsin L activity by use of the inhibitor CA-074 compared to cathepsin B activity in human lung tumor tissue.
In a series of pairs of lung tumor tissue and non-tumor lung parenchyma from 50 patients, the activity of cathepsin L was measured with Z-Phe-Arg-AMC using the inhibitor CA-074 to delimitate from cathepsin B activity also present in the tissue extracts. Cathepsin B was assessed in the same samples with its specific substrate Z-Arg-Arg-AMC. It was found that in tumor tissue the median activities of cathepsin L and cathepsin B were increased 1.6-fold and 4.9-fold, respectively. The levels of activity of both enzymes did not correlate with TNM stages nor with cell differentiation of bronchial carcinomas. Cathepsin L activity was found to be insignificantly higher in adenocarcinoma compared to squamous cell carcinoma, while cathepsin B activity did not vary across the histologies. The activities of both enzymes were low in pulmonary carcinoids, which are known to be low-grade malignant neoplasms. The amount of cathepsin B activity exceeded by far that of cathepsin L activity as proven by measurement with Z-Phe-Arg-AMC in the presence of the inhibitor Z-Phe-Phe-CHN2:95-98% of cathepsin B activity vs 2-5% of cathepsin L activity were determined. By SDS-PAGE separation and immunoblot analysis, it could be demonstrated that significant amount of cathepsin L is complexed with the cysteine proteinase inhibitor kininogen. This explains the rather low cathepsin L activity values in the tissue extracts.
Werle
B
B
Thoraxklinik Heidelberg-Rohrbach, Germany.
Ebert
W
W
Klein
W
W
Spiess
E
E
D000230:Adenocarcinoma / Q000201:enzymology; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000201:enzymology; D002401:Cathepsin B / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D056668:Cathepsin L; D002403:Cathepsins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000302:isolation & purification; D003546:Cysteine Endopeptidases / Q000032:analysis* / Q000302:isolation & purification; D015853:Cysteine Proteinase Inhibitors / Q000032:analysis / Q000302:isolation & purification; D004151:Dipeptides; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases; D006801:Humans; D007704:Kininogens / Q000378:metabolism; D008168:Lung / Q000201:enzymology; D008175:Lung Neoplasms / Q000201:enzymology*; D008875:Middle Aged; D008969:Molecular Sequence Data
D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D007704:Kininogens; C068250:N-(3-propylcarbamoyloxirane-2-carbonyl)-isoleucyl-proline; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L