Ceramide accumulation is independent of camptothecin-induced apoptosis in prostate cancer LNCaP cells.
We have investigated to determine the source of ceramide produced during the genotoxic apoptosis induced by the anti-cancer drug, camptothecin (CPT), in human prostate cancer LNCaP cells by measuring the activities of acid and neutral sphingomyelinases (SMase) and by using fumonisinB(1) (FB(1)), the inhibitor of ceramide synthase involving de novo synthesis of ceramide. In contrast to time-dependent elevation of intracellular ceramide level after CPT-treatment, the activities of both SMases were not increased but rather decreased. Instead, pretreatment for 3 h with FB(1) (100 microM), an inhibitor of ceramide synthase, almost completely abrogated ceramide accumulation observed in cells exposed to CPT for 18 h. These results indicate that ceramide is produced via de novo pathway but not via sphingomyelin hydrolysis pathway. Furthermore, it is to be noted that the pretreatment with FB(1) did not affect the CPT-induced apoptosis as assessed by DNA ladder formation, Hoechst 33342 staining, flow cytometry, and mitochondrial potential thereby leading us to propose that ceramide accumulation is independent of apoptosis in this system.
Akao
Yukihiro
Y
Gifu International Institute of Biotechnology, Mitake-cho 2193-128, Kani-gun, Gifu 505-0116, Japan.
Kusakabe
Suzuno
S
Banno
Yoshiko
Y
Kito
Mariko
M
Nakagawa
Yoshihito
Y
Tamiya-Koizumi
Keiko
K
Hattori
Masnori
M
Sawada
Motoshi
M
Hirabayasi
Yoshio
Y
Ohishi
Nobuko
N
Nozawa
Yoshinori
Y
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001562:Benzimidazoles; D002166:Camptothecin / Q000494:pharmacology*; D002264:Carboxylic Acids / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism*; D053938:DNA Fragmentation; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D037341:Fumonisins; D006801:Humans; D008297:Male; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D001562:Benzimidazoles; D002264:Carboxylic Acids; D002518:Ceramides; D004791:Enzyme Inhibitors; D037341:Fumonisins; D013109:Sphingomyelins; C056933:fumonisin B1; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; D013108:Sphingomyelin Phosphodiesterase; D020169:Caspases; C017807:bisbenzimide ethoxide trihydrochloride; D002166:Camptothecin