Affiliation:
1. Cancer Center Karolinska, Department of Oncology-Pathology, Karolinska Institute and Hospital, S-171 76 Stockholm, Sweden
Abstract
ABSTRACT
Calpain is a ubiquitous protease with potential involvement in apoptosis. We report that in human melanoma cells, cisplatin-induced calpain activation occurs early in apoptosis. Calpain activation and subsequent apoptosis were inhibited by calpeptin and PD150606, two calpain inhibitors with different modes of action. Furthermore, cisplatin induced cleavage of the BH3-only protein Bid, yielding a 14-kDa fragment similar to proapoptotic, caspase-cleaved Bid. However, Bid cleavage was inhibited by inhibitors of calpain, but not by inhibitors of caspases or of cathepsin L. Recombinant Bid was cleaved in vitro by both recombinant calpain and by lysates of cisplatin-treated cells. Cleavage was calpeptin sensitive, and the cleavage site was mapped between Gly70 and Arg71. Calpain-cleaved Bid induced cytochrome
c
release from isolated mitochondria. While calpeptin did not affect cisplatin-induced modulation of Bak to its proapoptotic conformation, a dominant-negative mutant of MEKK1 (dnMEKK) inhibited Bak modulation. dnMEKK did not, however, block Bid cleavage. The combination of dnMEKK and calpeptin had an additive inhibitory effect on apoptosis. In summary, calpain-mediated Bid cleavage is important in drug-induced apoptosis, and cisplatin induces at least two separate apoptotic signaling pathways resulting in Bid cleavage and Bak modulation, respectively.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
217 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献