Immunodetection of cathepsins B and L present in and secreted from human pre-malignant and malignant colorectal tumour cell lines.
Pre-malignant and malignant human colorectal tumour epithelial cell lines both secreted precursor forms of the 2 cysteine proteinases, cathepsins B and L. The amount of proteinases secreted by these cell lines varied according to the cell density. Comparison at similar cell densities showed that the pre-malignant, adenoma-derived cell line (PC/AA) secreted as much, or more, of both cathepsin B and L precursors as did the malignant, carcinoma-derived cell line (PC/JW/FI). However, mature forms of cathepsins B and L were detected in the culture media of only the carcinoma-derived cell line, thus indicating that the invasive potential of a tumour may be related to its ability to process extracellularly the secreted precursor enzyme to a mature and consequently active enzyme, rather than to the amount of proteinase synthesized and/or secreted. Similar results were obtained using 2 other epithelium-derived tumour cell lines, HT/29 (carcinoma) and SP/AN (adenoma). Immunolocation studies showed that cathepsin B was lysosomal while cathepsin L appeared to have a distribution more consistent with a plasma membrane association. Purified human cathepsins B and L (mature form) were capable of solubilizing an isolated basement membrane matrix (bovine anterior lens capsule) in vitro, thus indicating that the secreted mature enzymes and the membrane-associated cathepsin L could potentially degrade basal laminae or sub-endothelial basement membranes in vivo.
Maciewicz
R A
RA
AFRC Institute of Food Research-Bristol Laboratory, Langford, Bristol, Avon, UK.
Wardale
R J
RJ
Etherington
D J
DJ
Paraskeva
C
C
D000236:Adenoma / Q000201:enzymology*; D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D002277:Carcinoma / Q000201:enzymology*; D002401:Cathepsin B / Q000378:metabolism*; D056668:Cathepsin L; D002403:Cathepsins / Q000378:metabolism*; D002417:Cattle; D003094:Collagen / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000201:enzymology*; D003546:Cysteine Endopeptidases; D003593:Cytoplasm / Q000201:enzymology; D010450:Endopeptidases; D004792:Enzyme Precursors / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D008247:Lysosomes / Q000201:enzymology; D014407:Tumor Cells, Cultured
D004792:Enzyme Precursors; D003094:Collagen; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L