Assessment of cathepsin L activity by use of the inhibitor CA-074 compared to cathepsin B activity in human lung tumor tissue

Biol Chem Hoppe Seyler. 1995 Mar;376(3):157-64. doi: 10.1515/bchm3.1995.376.3.157.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma / enzymology
  • Adult
  • Aged
  • Amino Acid Sequence
  • Blotting, Western
  • Carcinoma, Squamous Cell / enzymology
  • Cathepsin B / analysis*
  • Cathepsin B / antagonists & inhibitors
  • Cathepsin B / metabolism
  • Cathepsin L
  • Cathepsins / analysis*
  • Cathepsins / antagonists & inhibitors
  • Cathepsins / isolation & purification
  • Cysteine Endopeptidases / analysis*
  • Cysteine Endopeptidases / isolation & purification
  • Cysteine Proteinase Inhibitors / analysis
  • Cysteine Proteinase Inhibitors / isolation & purification
  • Dipeptides*
  • Electrophoresis, Polyacrylamide Gel
  • Endopeptidases*
  • Humans
  • Kininogens / metabolism
  • Lung / enzymology
  • Lung Neoplasms / enzymology*
  • Middle Aged
  • Molecular Sequence Data


  • Cysteine Proteinase Inhibitors
  • Dipeptides
  • Kininogens
  • N-(3-propylcarbamoyloxirane-2-carbonyl)-isoleucyl-proline
  • Cathepsins
  • Endopeptidases
  • Cysteine Endopeptidases
  • Cathepsin B
  • CTSL protein, human
  • Cathepsin L