Mechanistic insight into taxol-induced cell death.
We analysed the involvement of proteases during taxol-mediated cell death of human A549 non-small-cell lung carcinoma cells using a proteomics approach that specifically targets protein N termini and further detects newly formed N termini that are the result of protein processing. Our analysis revealed 27 protease-mediated cleavages, which we divided in sites C-terminal to aspartic acid (Asp) and sites C-terminal to non-Asp residues, as the result of caspase and non-caspase protease activities, respectively. Remarkably, some of the former were insensitive to potent pancaspase inhibitors, and we therefore suggest that previous inhibitor-based studies that report on the caspase-independent nature of taxol-induced cell death should be judged with care. Furthermore, many of the sites C-terminal to non-Asp residues were also uniquely observed in a model of cytotoxic granule-mediated cell death and/or found by in vitro cataloging human mu-calpain substrates using a similar proteomics technique. This thus raises the hypothesis that killing tumor cells by chemotherapy or by immune cells holds similar non-Asp-specific proteolytic components with strong indications to calpain activity.
Impens
F
F
Department of Medical Protein Research, VIB, Ghent, Belgium.
Van Damme
P
P
Demol
H
H
Van Damme
J
J
Vandekerckhove
J
J
Gevaert
K
K
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology* / Q000627:therapeutic use; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000201:enzymology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D006801:Humans; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology* / Q000627:therapeutic use; D040901:Proteomics / Q000379:methods
D000972:Antineoplastic Agents, Phytogenic; D061945:Caspase Inhibitors; D009363:Neoplasm Proteins; D002154:Calpain; D020169:Caspases; C484806:CAPN1 protein, human; D017239:Paclitaxel