Figure 4

ASS1 expression during cisplatin and ADI-PEG 20 combination treatment in HCC cells. Cells were simultaneously treated with a cisplatin concentration of either 5 μM or 7.5 μM and increasing concentrations of ADI-PEG 20: 0.5, 1, 2, 4 and 8 nM in the same well. After 72 h, triplicate samples were assessed for cell viability by reading the luminescence and lysates were made out of the remaining identical rows. Luminescence values were used to load equal amounts of protein and ASS1 levels were assessed by western blot. ASS1 levels were normalized to GAPDH at each treatment condition and expressed relative to zero drug (100%). The data are representative of two to three independent experiments. Error bars represent S.D. An unpaired t-test was conducted to determine the significance of the change in ASS1 protein levels after each cisplatin and ADI-PEG 20 combination treatment as compared to the untreated, or zero drug sample (*p < 0.05, **p < 0.005, ***p < 0.001, ****p < 0.0001). (A) HepG2 cells. (B) HCC36 cells. (C) SNU182 cells.