Sugiol Suppresses the Proliferation of Human U87 Glioma Cells via Induction of Apoptosis and Cell Cycle Arrest

The diterpenoid, sugiol, has been reported to exert anticancer effects against a number of human cancers. However, the anticancer effects of sugiol have not been evaluated against the human glioma cells. The present study was designed to examine the effects of sugiol on the proliferation of human U87 glioma cells. The results showed that sugiol significantly (P < 0.05) suppressed the viability of the U87 cells in a concentration dependent manner and exhibited an IC(50) value of 15 μM. On the other hand, the growth inhibitory effects of sugiol were minimal on the normal human astrocytes. Acridine orange and ethidium bromide staining (AO/EB) staining revealed that sugiol induces apoptosis which was further confirmed by Western blot analysis, wherein upregulation of Bax and downregulation of Bcl-2 were observed in U87 cells. Flow cytometry showed that sugiol causes cell cycle arrest at the G(0)/G(1) stage. The relative percentage of G1 phase was found to be increased from 26.58% at 0 μM to 70.96% at 30 μM sugiol. Taken together, the results suggest sugiol inhibits the growth of glioma cells and may prove to be a lead molecule in the management of human glioma.