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  • Localization of cathepsin B in two human lung cancer cell lines
    Erdel, M. ...
    We demonstrated the cysteine proteinase cathepsin B in two human lung tumor cell lines by cytochemical and immunocytochemical methods. The cell lines werederived from a squamous cell carcinoma of the ... lung (HS-24) and a metastasis to the adrenal gland from an adenocarcinoma of the lung (SB-3). Forcomparison and control, normal human lung fibroblasts cells (Wi-38) were also investigated. Intracellular cathepsin B activity was detected in all three cell lines. SB-3 and the normal fibroblast cells showed almost equal cathepsin B activity, which was considerably stronger than that in the HS-24 cells. Specific inhibitors for cathepsin B (E64, leupeptin, antipain) suppressed its activity completely. Stefin A, the physiological cathepsin B inhibitor, was less effectiveč this might depend on its limited penetrability into living cells. Localization of the cathepsin B was performed by conventional immunofluorescence microscopy and laser scanning microscopy. Withspecific anti-cathepsin B antibodies, the enzyme was localized in HS-24, SB-3, and Wi-38 fibroblast cells within perinuclear granules representing the lysosomal compartment. In the SB-3 cells, we additionally localized a minor fraction of the enzyme bound to the plasma membrane in a speckled distribution, accessible to the antibodies from the outside. This direct demonstration of cathepsin B distribution supports biochemical data about the dual localization of the enzyme in tumor cells. It also supports the possibility of a direct involvement of cathepsin B in the degradation of the extracellular matrix, and thus a contribution of the enzyme in invasion and metastasis.
    Type of material - article, component part
    Publish date - 1990
    Language - english
    COBISS.SI-ID - 14022183