title: Cathepsin B in tumors, normal tissue and isolated cells from the human lung.
abstract: 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.
authors.affiliation: Thoraxklinik Heidelberg-Rohrbach, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Werle
authors.forename: W
authors.initials: W
authors.lastname: Ebert
authors.forename: W
authors.initials: W
authors.lastname: Klein
authors.forename: E
authors.initials: E
authors.lastname: Spiess
mesh_terms: D002401:Cathepsin B / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000201:enzymology*; D008175:Lung Neoplasms / Q000201:enzymology*; D016676:Macrophages, Alveolar / Q000201:enzymology; D008970:Molecular Weight
chemical_list: D004792:Enzyme Precursors; C057832:procathepsin B; D002401:Cathepsin B