Cell death after co-administration of cisplatin and ethacrynic acid.
Ethacrynic acid (EA) significantly enhances the ototoxic effects of cisplatin. To gain insights into the mechanisms underlying Cis/EA ototoxicity, cochleas were labeled with several apoptotic markers. Cis/EA treatment caused extensive outer hair cell (OHC) and inner hair cell (IHC) damage; OHC lesions decreased from the base towards apex of the cochlea whereas the IHC lesion was relatively constant (25-60%) along the length of the cochlea. Propidium iodide labeled OHC nuclei appeared relatively normal at 6h post-treatment, were condensed and fragmented at 12h post-treatment and were frequently missing 48 h post-treatment. Initiator caspase 8, associated with membrane death receptors, and TRADD, a protein that recruits caspase 8, were present in OHC at 6h post-treatment. Caspase 8 labeling increased from 6 to 24h, but was largely absent at 48 h post-treatment. Executioner caspase 3 and caspase 6, which lie downstream of caspase 8, were expressed in OHC 12-24h post-treatment. Initiator caspase 9, associated with mitochondrial damage, was only expressed at low levels at 48 h post-treatment. These results suggest that the rapid onset of Cis/EA induced programmed cell death is initiated by membrane death receptors associated with TRADD and caspase 8.
Ding
Dalian
D
Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY 14214, USA.
Jiang
Haiyan
H
Wang
Ping
P
Salvi
Richard
R
D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000633:toxicity; D017209:Apoptosis / Q000187:drug effects*; D053181:Caspase 8 / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002682:Chinchilla; D002945:Cisplatin / Q000008:administration & dosage* / Q000633:toxicity*; D004232:Diuretics / Q000008:administration & dosage / Q000633:toxicity; D004357:Drug Synergism; D004976:Ethacrynic Acid / Q000008:administration & dosage* / Q000633:toxicity*; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D008855:Microscopy, Electron, Scanning; D013316:Stria Vascularis / Q000187:drug effects / Q000473:pathology; D053199:TNF Receptor-Associated Death Domain Protein / Q000378:metabolism
D000970:Antineoplastic Agents; D004232:Diuretics; D053199:TNF Receptor-Associated Death Domain Protein; D053181:Caspase 8; D020169:Caspases; D004976:Ethacrynic Acid; D002945:Cisplatin