PT - JOURNAL ARTICLE AU - Chiung-Huei Peng AU - Chien-Ning Huang AU - Shu-Ping Hsu AU - Chau-Jong Wang TI - Penta-Acetyl Geniposide Induce Apoptosis in C6 Glioma Cells by Modulating the Activation of Neutral Sphingomyelinase-Induced p75 Nerve Growth Factor Receptor and Protein Kinase Cδ Pathway AID - 10.1124/mol.106.022178 DP - 2006 Sep 01 TA - Molecular Pharmacology PG - 997--1004 VI - 70 IP - 3 4099 - http://molpharm.aspetjournals.org/content/70/3/997.short 4100 - http://molpharm.aspetjournals.org/content/70/3/997.full SO - Mol Pharmacol2006 Sep 01; 70 AB - In our previous studies, we demonstrated the apoptotic cascades protein kinase C (PKC) δ/c-Jun NH2-terminal kinase (JNK)/Fas/caspases induced by penta-acetyl geniposide [(Ac)5GP]. However, the upstream signals mediating PKCδ activation have not yet been clarified. Ceramide, mainly generated from the degradation of sphingomyelin, was hypothesized upstream above PKCδ in (Ac)5GP-transduced apoptosis. Furthermore, nerve growth factor (NGF)/p75 is supposed to be involved because(Ac)5GP-induced apoptosis was demonstrated previously in glioma cells. In the present study, (Ac)5GP was shown to activate neutral sphingomyelinase (N-SMase) immediately, with its maximum at 15 min. The NGF and p75 enhanced by (Ac)5GP was inhibited when added with GW4869, the N-SMase inhibitor, indicating NGF/p75 as the downstream signals of N-SMase/ceramide. To investigate whether N-SMase is involved in (Ac)5GP-transduced apoptotic pathway, cells were treated with (Ac)5GP added with or without GW4869. It showed that N-SMase inhibition blocked FasL expression and caspase 3 activation. Likewise, p75 antagonist peptide attenuated the FasL/caspase 3 expression. The PKCδ translocation induced by (Ac)5GP was also eliminated by GW4869 and p75 antagonist peptide. To further confirm whether N-SMase activation plays an important role in (Ac)5GP-induced apoptosis, cells were analyzed the apoptotic rate by 4′, 6-diamidino-2-phenylindole (DAPI) staining. (Ac)5GP-induced apoptosis was reduced 40 and 80% by 10 and 20 μM GW4869, respectively. It indicated that N-SMase activation is pivotal in (Ac)5GP-mediated apoptosis. In conclusion, SMase and NGF/p75 are suggested to mediate upstream above PKCδ, thus transducing FasL/caspase cascades in (Ac)5GP-induced apoptosis. The American Society for Pharmacology and Experimental Therapeutics