Cytochemical and biochemical evidence of cathepsin B in malignant, transformed and normal breast epithelial cells.
Human breast cancer cell lines, as well as transformed mammary epithelial cells (HBL-100) and growth-stimulated normal breast epithelial cells showed positive cytochemical reaction with the proteinase substrate 2-(N-benzyloxycarbonyl-L-arginyl-L-arginylamido)-4-methoxynapht halene, in the presence of 5-nitrosalicylaldehyde. The reaction product, small fluorescent granules, was distributed throughout the cytoplasm, in the perinuclear zone, in some cytoplasmic projections, and at the cell surface. Using a panel of various proteinase inhibitors, we found that the formation of the reaction product was an enzymic function of a cysteine proteinase. Using the substrate 7-(N-benzyloxycarbonyl-L-arginyl-L-arginylamido)-4-methylcoumarin, we evaluated some biochemical properties of the cysteine proteinase, including pH-activity profile, pH stability, apparent relative molecular mass and sensitivity toward various proteinase inhibitors. We found that the proteinase from the studied breast epithelial cells exhibited characteristics of a mature form of cathepsin B. Taken together, the cytochemical and biochemical data provide evidence that human breast epithelial cells of cancer origin, as well as in the transformed or growth-stimulated state express active cathepsin B and compartmentalize it into specific subcellular sites.
Krepela
E
E
Research Institute of Clinical and Experimental Oncology, Brno, Czechoslovakia.
Bártek
J
J
Skalková
D
D
Vicar
J
J
Rasnick
D
D
Taylor-Papadimitriou
J
J
Hallowes
R C
RC
D001940:Breast / Q000201:enzymology*; D001943:Breast Neoplasms / Q000201:enzymology*; D002401:Cathepsin B / Q000378:metabolism*; D002460:Cell Line; D002471:Cell Transformation, Neoplastic / Q000201:enzymology*; D002850:Chromatography, Gel; D004848:Epithelium / Q000201:enzymology; D006801:Humans; D008856:Microscopy, Fluorescence
D002401:Cathepsin B