Author/Editor		Erdel, M; Trefz, G; Spiess, E; Habermaas, S; Spring, H; Lah, T; Ebert, W
Title		Localization of cathepsin B in two human lung cancer cell lines
Type		članek
Source		J Histochem Cytochem
Vol. and No.		Letnik 38, št. 9
Publication year		1990
Volume		str. 1313-21
Language		eng
Abstract		We demonstrated the cysteine proteinase cathepsin B in two human lung tumor cell lines by cytochemical and immunocytochemical methods. The cell lines were derived 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). For comparison 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 effective; 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. With specific 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.
Descriptors		ADENOCARCINOMA CARCINOMA, SQUAMOUS CELL CATHEPSIN B LUNG NEOPLASMS ADENOCARCINOMA CARCINOMA, SQUAMOUS CELL CELL LINE CELL MEMBRANE FIBROBLASTS FLUORESCENT ANTIBODY TECHNIQUE IMMUNOHISTOCHEMISTRY LUNG NEOPLASMS LYSOSOMES TUMOR CELLS, CULTURED