β-elemene Induces Caspase-dependent Apoptosis in Human Glioma Cells in vitro through the Upregulation of Bax and Fas/ FasL and Downregulation of Bcl-2

Background: β-elemene, extracted from herb medicine Curcuma wenyujin has potent anti-tumor effects invarious cancer cell lines. However, the activity of β-elemene against glioma cells remains unclear. In the presentstudy, we assessed effects of β-elemene on human glioma cells and explored the underlying mechanism. Materialsand
Methods: Human glioma U87 cells were used. Cell proliferation was determined with MTT assay andcolony formation assay to detect the effect of β-elemene at different doses and times. Fluorescence microscopywas used to observe cell apoptosis with Hoechst 33258 staining and change of glioma apoptosis and cell cyclingwere analyzed by flow cytometry. Real-time quantitative PCR and Western-blotting assay were performed toinvestigated the influence of β-elemene on expression levels of Fas/FasL, caspase-3, Bcl-2 and Bax. The experimentwas divided into two groups: the blank control group and β-elemne treatment group.
Results: With increase inthe concentration of β-elemene, cytotoxic effects were enhanced in the glioma cell line and the concentrationof inhibited cell viability (IC50) was 48.5 μg/mL for 24h. β-elemene could induce cell cycle arrest in the G0/G1phase. With Hoechst 33258 staining, apoptotic nuclear morphological changes were observed. Activation ofcaspase-3,-8 and -9 was increased and the pro-apoptotic factors Fas/FasL and Bax were upregulated, whilethe anti-apoptotic Bcl-2 was downregulated after treatment with β-elemene at both mRNA and protein levels.Furthermore, proliferation and colony formation by U87 cells were inhibited by β-elemene in a time and doesdependentmanner.
Conclusions: Our results indicate that β-elemene inhibits growth and induces apoptosis ofhuman glioma cells in vitro. The induction of apoptosis appears to be related with the upregulation of Fas/FasLand Bax, activation of caspase-3,-8 and -9 and downregulation of Bcl-2, which then trigger major apoptoticcascades.