β-Elemene inhibits Hsp90/Raf-1 molecular complex inducing apoptosis of glioblastoma cells

beta-Elemene, an active component of herb medicine Curcuma wenyujin, has been shown to antagonize glioblastoma cells by inducing apoptosis. However, how beta-elemene induces apoptosis of these cells remains unclear. In this study, we report that beta-elemene disrupted the formation of the Hsp90/Raf-1 complex, a key step in maintaining the conformation stability of Raf-1, and caused deactivation of Raf-1 and inhibition of the ERK pathway, thereby leading to apoptosis of glioblastoma cells. Specifically, treatment of glioblastoma cell lines with beta-elemene attenuated phosphorylation of multiple members of the kinase families in the Ras/Raf/MEK/ERK cascade, including Raf-1 and ERK as well as downstream signaling targets such as Bcl-2. These results suggest that the Hsp90/Raf-1 complex could be a promising molecular target for new drug development for the treatment of glioblastoma.