Figure 6.

JS‐K down‐regulates mitochondria respiratory chain (MRC) complex I and IV core proteins, as well as antioxidant enzymes. A, The effect of JS‐K on MRC complex activities in SGC7901 cells. Cells were treated with JS‐K at the indicated concentration for 12 h and then harvested to measure MRC complex activities using specific assay kits. The relative activities of the MRC complexes were calculated by normalizing the MRC complex activities in all the groups with the activity of a negative control group. **P < 0.01. B, N‐acetyl‐L‐cysteine (NAC) partially reversed the reduction of MRC complex I and IV activity induced by JS‐K. SGC7901 cells were treated with JS‐K in the absence or presence of NAC for 12 h, and the MRC complex I and IV activity was measured using specific kits. **P < 0.01. C, JS‐K decreased MRC complex I and IV activity in gastric cancer xenografts. The isolated gastric tumour tissues were lysed by homogenization and sonication, and the activities of MRC complex I and IV in the lysates were measured with specific assay kits. The relative MRC complex activities were calculated by normalizing the activities of MRC complex I and IV in all the groups with those in a negative control group. **P < 0.01. D, JS‐K down‐regulates Ndufs4 and COX2 in SGC7901 cells. Cells were treated with JS‐K at the indicated time‐points and then collected to determine the protein level of Ndufs4 and COX2 by Western blot. Actin was used as a loading control. E, JS‐K administration suppresses Ndufs4 and COX2 expression in tumour tissues. The tumour tissues isolated from the mice used in Figure 5C were minced and lysed, and Western blot assays were used to determine the protein levels of Ndfus4 and COX2 in the tumour tissue lysates. GAPDH was used as a loading control. F, JS‐K decreases SOD1 and catalase activity in SGC7901 cells. Cells were treated with JS‐K at the indicated concentration for 12 h and collected to measure SOD1 and catalase activity using specific assay kits. The activity in JS‐K‐treated groups was normalized to that in the control group. *P < 0.05, **P < 0.01. G, JS‐K decreases SOD1 and catalase activity in gastric tumour tissues. The lysates of isolated gastric tumour tissues (Figure 5A) were used to measure the activities of SOD1 and catalase using specific assay kits, and the relative activities were normalized by comparing the activities of SOD1 and catalase in all groups with those in a negative control group. **P < 0.01. H, JS‐K down‐regulates SOD1 and catalase in SGC7901 cells. Cells were treated with JS‐K at the indicated concentrations for 12 h and then harvested to detect the protein levels of SOD1 and catalase with Western blot analysis. Actin was used as a loading control. I, JS‐K administration suppresses SOD1 and catalase expression in gastric tumour tissues. Tumour tissues were isolated from the negative control and JS‐K‐treated mice used in Figure 5C and minced and lysed to determine SOD1 and catalase protein levels using Western blot. Actin was used as a loading control