Cathepsin B in tumors, normal tissue and isolated cells from the human lung

Anticancer Res. May-Jun 1994;14(3A):1169-76.


Human lung tumors of different histologic cell types and adjacent normal lung parenchyma, purified lung parenchyma, purified lung macrophages and three human lung-derived cell lines were investigated in an attempt to identify tumor specific premature and mature cathepsin B species. By polyacrylamide gel electrophoresis and immunoblotting techniques with specific antibodies we detected mature cathepsin B forms with molecular masses of 31 kDa and 32 kDa in tissues. Reductive conditions revealed in these populations single and double chain 31/32 kDa forms. The latter were recognized by their heavy part, the 26/27 kDa molecule forms. Qualitative differences in the pattern of cathepsin B species between tumor and corresponding normal material or between different histologies of lung tumors were not found. However, tumor material is considerably richer in cathepsin B activity than normal material. Isolated alveolar macrophage populations and established cell lines showed the same cathepsin B pattern as tissues. All these cells released cathepsin B proforms of 44 to 46 kDa into the culture medium, indicating that the release of pro-cathepsin B cannot be considered a tumor-specific mechanism. The secreted proforms were sensitive to in vitro activation by pepsin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cathepsin B / analysis*
  • Cathepsin B / genetics
  • Cathepsin B / metabolism
  • Cell Line
  • Enzyme Precursors / metabolism
  • Humans
  • Lung / enzymology*
  • Lung Neoplasms / enzymology*
  • Macrophages, Alveolar / enzymology
  • Molecular Weight


  • Enzyme Precursors
  • procathepsin B
  • Cathepsin B