Lysosomal proteases as potential targets for the induction of apoptotic cell death in human neuroblastomas.
Neuroblastoma is the most common type of cancer in infants. In children this tumor is particularly aggressive; despite various new therapeutic approaches, it is associated with poor prognosis. Given the importance of endosomal-lysosomal proteolysis in cellular metabolism, we hypothesized that inhibition of lysosomal protease would impact negatively on neuroblastoma cell survival. Treatment with E-64 or CA074Me (2 specific inhibitors of cathepsin B) or with pepstatin A (a specific inhibitor of cathepsin D) was cytotoxic for 2 neuroblastoma cell lines having different degrees of malignancy. Cell death was associated with condensation and fragmentation of chromatin and externalization of plasma membrane phosphatidylserine, 2 hallmarks of apoptosis. Concomitant inhibition of the caspase cascade protected neuroblastoma cells from cathepsin inhibitor-induced cytotoxicity. These data indicate that prolonged inhibition of the lysosomal proteolytic pathway is incompatible with cell survival, leading to apoptosis of neuroblastoma cells, and that the cathepsin-mediated and caspase-mediated proteolytic systems are connected and cooperate in the regulation of such an event. Since modern antitumor chemotherapy is aimed at restoring the normal rate of apoptosis in neoplastic tissues, the demonstration that endosomal-lysosomal cathepsins are involved in this process may constitute a basis for novel strategies that include cathepsin inhibitors in the therapeutic regimen.
Castino
Roberta
R
Dipartimento di Scienze Mediche, Laboratorio di Patologia Molecolare, Università A. Avogadro, Novara, Italy.
Pace
Deborah
D
Démoz
Marina
M
Gargiulo
Marco
M
Ariatta
Chiara
C
Raiteri
Elisabetta
E
Isidoro
Ciro
C
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D001932:Brain Neoplasms / Q000201:enzymology / Q000473:pathology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002401:Cathepsin B / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D002402:Cathepsin D / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000187:drug effects / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D006801:Humans; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008247:Lysosomes / Q000201:enzymology*; D009447:Neuroblastoma / Q000201:enzymology / Q000473:pathology*; D010436:Pepstatins / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000590:Amino Acid Chloromethyl Ketones; C400541:CA 074 methyl ester; D061945:Caspase Inhibitors; D002843:Chromatin; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D010436:Pepstatins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases; D002401:Cathepsin B; D002402:Cathepsin D; D007930:Leucine; C024974:E 64; C031375:pepstatin