Role of caspase 3-dependent Bcl-2 cleavage in potentiation of apoptosis by Bcl-2.
Previous studies from our laboratory have demonstrated that Bcl-2 has a proapoptotic effect on neocarzinostatin (NCS)-treated PC12 pheochromocytoma cells. In the present study, we examine the mechanisms of this effect and demonstrate its relevance for the in vivo situation. Four hours after NCS treatment, a 23-kDa cleavage product of Bcl-2 was detected in whole cell lysates of bcl-2-transfected PC12 cells. In contrast, bcl-2 transfection protected PC12 cells from cisplatin-induced apoptosis, and cisplatin treatment did not result in Bcl-2 cleavage. Similarly, Bcl-2 cleavage did not occur and Bcl-2-mediated protection from, rather than potentiation of apoptosis was observed after NCS treatment of MCF-7 breast cancer cells. The caspase 3-specific inhibitor Ac-DEVD-CHO prevented Bcl-2 cleavage and attenuated NCS-induced apoptosis in bcl-2-transfected PC12 cells, whereas it had no effect on NCS-induced apoptosis in mock-transfected PC12 cells. Furthermore, MCF-7 cells do not express caspase 3, a finding in concert with the lack of Bcl-2 cleavage in this line. In in vivo experiments, xenografts of bcl-2-transfected PC12 cells were more susceptible to NCS toxicity than were xenografts of mock-transfected PC12 cells. Caspase 3-mediated Bcl-2 cleavage therefore plays an important role in the potentiation by Bcl-2 of NCS-induced apoptosis.
Liang
Ye
Y
The Pediatric Center for Neuroscience, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Nylander
Karen D
KD
Yan
Chaohua
C
Schor
Nina Felice
NF
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002945:Cisplatin / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004195:Disease Models, Animal; D004347:Drug Interactions; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009842:Oligopeptides / Q000494:pharmacology; D016716:PC12 Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D014162:Transfection; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D009353:Zinostatin / Q000494:pharmacology
D000970:Antineoplastic Agents; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D009842:Oligopeptides; D019253:Proto-Oncogene Proteins c-bcl-2; C099158:acetyl-aspartyl-glutamyl-valyl-aspartal; D009353:Zinostatin; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D002945:Cisplatin