• Journal of Life Science
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• v.22 no.6
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• pp.760-771
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• 2012

Marine triterpene glycosides are physiologically active natural compounds isolated from sea cucumbers(holothurians). It was demonstrated that they have a wide range of biological activities, including antifungal, cytotoxic, and antitumor effects. A previous study showed that stichoposide C (STC) isolated from Thelenota anax induces apoptosis through generation of ceramide by activation of acid sphingomyelinase (SMase) and neutral SMase in human leukemia cells. In this study, we investigated whether STD, a structural analog of STC, can induce apoptosis and examined the molecular mechanisms for its activity. It was found that STC and STD induce apoptosis in a dose- and time-dependent manner and lead to the activation of caspase-8, mitochondrial damage, activation of caspase-9, and activation of caspase-3 in K562 and HL-60 cells. STC activates acid SMase and neutral SMase, which results in the generation of ceramide. Specific inhibition of acid SMase or neutral SMase partially blocked STC-induced apoptosis, but not STD-induced apoptosis. In contrast, STD generates ceramide through the activation of ceramide synthase. Specific inhibition of ceramide synthase partially blocked STD-induced apoptosis, but not STC-induced apoptosis. Moreover, STC and STD markedly reduced tumor growth of HL-60 xenograft tumors and increased ceramide generation in vivo. These results indicate that STC and STD can induce apoptosis and have antitumor activity through the different molecular mechanisms, because they have a different sugar residue attached to aglycones. Thus, these results suggest that their actions are affected by a sugar residue attached to aglycones and they can be used as anticancer agents in the treatment of leukemia.