title: Micro-calpain regulates caspase-dependent and apoptosis inducing factor-mediated caspase-independent apoptotic pathways in cisplatin-induced apoptosis.
abstract: Cisplatin, an effective anticancer agent, can induce tumor cell apoptosis via caspase-dependent and-independent pathways. However, the precise mechanism that regulates the pathways remains unclear. In this study, we showed that micro-calpain mediated both caspase-dependent and-independent pathways during cisplatin-induced apoptosis in human lung adenocarcinoma cells. After cisplatin treatment, calpain activation, as measured by a fluorescent substrate, was an early event, taking place well before apoptosis inducing factor (AIF) release and caspase-9/-3 activation. Confocal imaging of cells transfected with AIF-GFP demonstrated that AIF release occurred about 9 hr after cisplatin treatment. The increase of micro-calpain activity proved to be a crucial event in the apoptotic machinery, as demonstrated by the significant protection of cell death in samples suppressed the endogenous micro-calpain expression level, as well as cotreated with the calpain inhibitors, calpeptin and PD150606. Inhibition of mu-calpain not only significantly reduced caspase-9/-3 activities but also completely blocked AIF redistribution. Our study also showed that endogenous mitochondrial micro-calpain could directly induce the truncation and release of AIF, while caspases and cathepsins were not necessary for this process. In conclusion, the study demonstrated that activation of micro-calpain played an essential role in regulating both caspase-dependent and AIF-mediated caspase-independent apoptotic pathways in cisplatin-induced apoptosis.
authors.affiliation: MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.forename: Da
authors.initials: D
authors.lastname: Xing
authors.forename: Wei R
authors.initials: WR
authors.lastname: Chen
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D015153:Blotting, Western; D002154:Calpain / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism*; D002945:Cisplatin / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D013347:Subcellular Fractions; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D051033:Apoptosis Inducing Factor; D034741:RNA, Small Interfering; D002154:Calpain; D020169:Caspases; C449002:mu-calpain; D002945:Cisplatin