Fig. 3
From: Sur-X, a novel peptide, kills colorectal cancer cells by targeting survivin-XIAP complex
Sur-X induced apoptosis in colorectal cancer cells by promoting the degradation of survivin and XIAP. a The real-time detection of RLU (phosphatidylserine and Annexin V binding, apoptosis) in HCT116 cells over 6 h with indicated concentrations of Sur-X. NT, no treatment. Three independent experiments were performed. b The activity of Caspase 3 in HCT116 and RKO with or without treatment of 10 μM Sur-X or Con for 1 h. The relative Caspase 3 activity was presented as percentage of untreated group, mean and SD of three independent experiments are shown. NT, no treatment. c HCT116 and RKO cells were treated by 10 μM of Sur-X (0.5, 1, 3 and 6 h) or Con (6 h), the expression levels of apoptosis-related proteins were detected by Western blot analysis. GAPDH was used as a loading control. NT, no treatment. Three independent experiments were performed. d The effect of Sur-X on the mRNA expression of survivin and XIAP in HCT116 cells. The expression value was presented as fold change of untreated group, mean and SD of three independent experiments are shown. NT, no treatment. ns, not significant. e The protein expression of survivin and XIAP in HCT116 cells with the treatment of 10 μM Sur-X or Con in combination with 10 μg/ml CHX for indicated time. GAPDH was used as a loading control. Three independent experiments were performed. f The effect of Sur-X on the ubiquitination of survivin and XIAP. After pretreated by MG132 (10 μM) for 8 h, HCT116 cells were treated by 10 μM Sur-X for 1 h. Three independent experiments were performed. g-h Effect of z-VAD-pretreatment on Sur-X-induced cell death in HCT116 (top) and RKO (bottom) assessed by Annexin V/7-AAD assay (g). Quantification of Annexin V positive cells, mean and SD of three independent experiments are shown. NT, no treatment; z-VAD, cells were treated only by z-VAD; Sur-X, cells were treated by Sur-X (10 μM) for 6 h; z-VAD + Sur-X, cells were pretreated by z-VAD (50 μM) for 12 h and then treated by Sur-X in combination with z-VAD for another 6 h (h). *, p < 0.05; **, p < 0.01; ***, p < 0.001; ****, p < 0.0001; ns, not significant