Studies on Inhibition of Juglone on Sarcoma 180 in Mice

To study the anti-tumor effect and mechanism of juglone on the mice xenotransplant model of sarcoma 180 in vivo. S₁₈₀ tumor-bearing mice were set up to investigate the effects of juglone on tumor growth. After HE staining, the pathomorphologic changes of tumor cells were observed by optical microscope. The ultrastructural changes of tumor cells were observed by transmission electron microscopy. Flow cytometry was used to observe the apoptosis rate and cell cycle arrest in S₁₈₀ cells. The experimental results showed that the tumor inhibition rate at the dosage of 2, 4 and 8 mumol/kg of juglone was 29.04%, 37.33%, 52.66% respectively. The tumor weight of all dose groups of juglone were lower significantly than that in blank control group (P<0.01). Under the optical microscope, the necrosis degree of the tumor cells increased significantly as the concentration of juglone increased compared with the blank control group. The typical morphological changes of apoptosis were observed, such as chromatin condensation, margination against nuclear envelope and formation of apoptotic bodies by transmission electron microscopy. The subdiploid peak was found and the apoptosis rate of juglone at the dosage of 2, 4 and 8 mumol/kg was 5.58plusmn0.63%, 6.66plusmn0.85%, 10.27plusmn1.05% respectively. The percentage of cells in G₁ phase of the cell cycle was decreased, whereas the amount of cells in the G₂/M phase was increased. Juglone perhaps induced G₂/M cell cycle arrest, which needs further research. Inducing apoptosis and G₂/M phase cycle arrest play important roles in the anti-tumor effect of juglone.