Silibinin induced autophagic and apoptotic cell death in HT1080 cells through a reactive oxygen species pathway

Hepatoprotectant silibinin has anticancer and chemo-preventive effects. in this study,silibinin showed significant inhibitory effect on human fibroblast ht 1080 cell growth cultured in media containing 10% fetal bovine serum or in serum free media,and in the latter case,silibinin exerted a more significant effect. silibinin induced autophagy at 12 h,confirmed by monodansylcadervarine (mdc) staining,up-regulation of beclin 1 (initiation factor for autophagosome formation),and conversion of lc3 i to lc3 ii (autophagosome marker). it also induced apoptosis at 24 h,proved by observation of apoptotic body and activation of caspase-3. 3-methyladenine (3-ma) inhibited silibinin-induced autophagy and promoted cell survival,suggesting that autophagy enhanced silibinin-induced apoptosis in ht1080 cells. silibinin generated reactive oxygen species (ros) in ht1080 cells,and the ros scavenger n -acetylcysteine (nac) reversed the cytotoxicity of silibinin,resulting in cell survival by inhibition of autophagic and apoptotic pathways. application of specific antioxidants demonstrated that h2 o2 was a major factor in silibinin-induced ros since the h2 o2 scavenger catalase reduced both autophagy and cell death. o2 • - also contributed to silibinin-induced cell death. © 2010 the japanese pharmacological society.