Fig. 5: Autophagy promoted silibinin-induced cystine depletion and p53 phosphorylation.

a Cysteine assay showed that silibinin induced time-dependent depletion of cysteine. b, c Western blotting analysis proved that silibinin downregulated xCT, but upregulated p53 and phospho-p53 in a time-dependent manner. These were all prevented in the presence of 3MA or bafilomycin A1. d Cysteine assay demonstrated that silibinin-induced depletion of cysteine was prevented in the presence of 3MA or bafilomycin A1. e Western blotting demonstrated that knockdown of ATG5 with SiRNA prevented silibinin-induced downregulation of CT and upregulation of p53 and phospho-p53. f Cysteine assay proved that silibinin-induced depletion of cysteine was inhibited when ATG5 was knocked down with SiRNA. #p < 0.05 versus control group; *p < 0.01 versus control group. The values are expressed as mean ± SEM (n = 5 per group).