Blockage of Autophagy Increases Timosaponin AIII-Induced Apoptosis of Glioma Cells In Vitro and In Vivo

Abstract

Timosaponin AIII (TSAIII), a saponin isolated from Anemarrhena asphodeloides and used in traditional Chinese medicine, exerts antitumor, anti-inflammatory, anti-angiogenesis, and pro-apoptotic activity on a variety of tumor cells. This study investigated the antitumor effects of TSAIII and the underlying mechanisms in human glioma cells in vitro and in vivo. TSAIII significantly inhibited glioma cell viability in a dose- and time-dependent manner but did not affect the growth of normal astrocytes. We also observed that in both glioma cell lines, TSAIII induces cell death and mitochondrial dysfunction, consistent with observed increases in the protein expression of cleaved-caspase-3, cleaved-caspase-9, cleaved-PARP, cytochrome c, and Mcl-1. TSAIII also activated autophagy, as indicated by increased accumulation of the autophagosome markers p62 and LC3-II and the autolysosome marker LAMP1. LC3 silencing, as well as TSAIII combined with the autophagy inhibitor 3-methyladenine (3MA), increased apoptosis in GBM8401 cells. TSAIII inhibited tumor growth in xenografts and in an orthotopic GBM8401 mice model in vivo. These results demonstrate that TSAIII exhibits antitumor effects and may hold potential as a therapy for glioma.

Keywords

• glioma
• timosaponin AIII
• apoptosis
• autophagy
• LC3-II