Costunolide-induced apoptosis is caused by receptor-mediated pathway and inhibition of telomerase activity in NALM-6 cells.
Costunolide, isolated from the stem bark of Magnolia sieboldii, is a sesquiterpene lactone that exhibits various biological and immunological actions. We investigated the induction mechanism of apoptosis by costunolide in a human B cell leukemia NALM-6 cell culture system. Costunolide (10 microM)-induced apoptosis time-dependently increased, estimated by nuclear damage observation and flow cytometric analysis. Costunolide did not change Fas-associated factor 1 (FAF1), but the phosphorylation of Fas-associated death domain (FADD) at serine 194 increased from early treatment. The activation of caspase-8 and -9 and degradation of poly-(ADP-ribose) polymerase (PARP) was time-dependently detected by incubation with costunolide. Pretreatment of cells with caspase-3, -8 and broad spectrum caspase inhibitors significantly blocked costunolide-induced apoptosis, but caspase-9 inhibitor failed to block apoptosis. Telomerase activity was significantly suppressed after treatment with costunolide, and human telomerase reverse transcriptase (hTERT), a critical determinant of the enzyme activity of telomerase, decreased the expression of both mRNA and protein levels by costunolide. Costunolide-induced repression of telomerase was prevented by pretreatment of cells with caspase-3, -8 and broad spectrum caspase inhibitors, but caspase-9 inhibitor was no effect. These data suggest that one of the costunolide-induced apoptotic mechanisms is that the receptor-mediated pathway precedes the mitochondria-dependent pathway, caused by the inhibition of telomerase activity via suppression of hTERT in NALM-6 cells.
Kanno
Syu-ichi
S
Department of Clinical Pharmacotherapeutics, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan. syu-kan@tohoku-pharm.ac.jp
Kitajima
Yasue
Y
Kakuta
Mai
M
Osanai
Yuu
Y
Kurauchi
Kaori
K
Ujibe
Mayuko
M
Ishikawa
Masaaki
M
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000502:physiology; D015153:Blotting, Western; D020169:Caspases / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D011955:Receptors, Drug / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012717:Sesquiterpenes / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects*; D019098:Telomerase / Q000037:antagonists & inhibitors*; D007783:Lactones
D000972:Antineoplastic Agents, Phytogenic; D051017:Apoptosis Regulatory Proteins; D020169:Caspases; D004791:Enzyme Inhibitors; D012313:RNA; D011955:Receptors, Drug; D012717:Sesquiterpenes; D019098:Telomerase; C002602:costunolide; D007783:Lactones