Penta-acetyl geniposide-induced C6 glioma cell apoptosis was associated with the activation of protein kinase C-delta

Abstract

Herbal medicine has been utilized to treat a variety of diseases, including cancer. On the other hand, disturbance of apoptosis is often observed in cancer cells. It has been reported that protein kinase C (PKC) isoforms are involved in the signaling of apoptosis. In the present study, we investigate the antitumor effect and possible mechanism of a herbal-originated product, (Ac) 5GP. We demonstrate that (Ac) 5GP treatment results in DNA fragmentation of C6 glioma cells dose-dependently. Stimulated by (Ac) 5GP, PKCδ and PKCζ were activated and translocated to the cell membrane fraction. Flow cytometry analysis showed that PKCδ, but not PKCζ inhibition blocks the (Ac) 5GP-induced apoptosis by decreasing the cell population of sub G1 peak. However, the mRNA levels of PKCδ and PKCζ were not altered by (Ac) 5GP-induced glioma cell apoptosis. These results suggested that the treatment of (Ac) 5GP induces apoptosis of tumor cells through the activation but not the synthesis of PKCδ.