Extract from Zanthoxylum piperitum Induces Apoptosis of AGS Gastric Cancer Cells Through Akt/MDM2/p53 Signaling Pathway

Objective: To determine the effect of Zanthoxylum piperitum extracet (ZPE) on apoptosis and analyze anticancer substances in ZPE, changes in proteins related to apoptosis, and pathological changes in tumors in mouse. Methods: Fifteen 4-week-old female BALB/c nu/nu mice were divided into 3 groups depending on ZPE dose, with 5 in each group. AGS gastric carcinoma cells (1x10(6) cells/200 mu L) were subcutaneously injected into the flank of each mouse. One week after the injection of AGS cells, ZPE was administered to the skin tissue [10 or 50 mg/(kg.d)] in the low- and high-dose groups, respectively for 20 days. Control animals were injected with vehicle only. After 3 weeks, the tumor was extracted and carried out for immunohistochemistry, the tendency of apoptosis and p53 in the body was checked using TdT-mediated dUTP nick-end labeling (TUNEL) assay. For 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, annexin V dead cell staining, cell cycle arrest and Western blotting, AGS gastric carcinoma cells were incubated with various concentrations of ZPE for 24 h. Cell survival rates were analyzed by MTT assays. Apoptosis was analyzed using annexin V dead cell staining and cell cycle arrest and measured using Muse cell analyzer. Results: High performance liquid chromatography (HPLC) analysis showed that ZPE contained organic sulfur compounds such as alliin and S-allylcysteine. MTT assay results revealed that ZPE (10-85 mu g/mL) could effectively inhibit the growth of AGS gastric cancer cells at higher concentrations ( P<0.05, P<0.01). The annexin V & dead cell staining assay and cell cycle arrest assay confirmed a dose-dependent increase in the apoptosis rate and G(1) phase in ZPE (10-70 mu g/mL) groups. ZPE decreased the expression of anti-apoptotic proteins (p-Akt, p-MDM2, Bcl-2), while increased pro-apoptotic proteins (cleaved PARP, p53, pro-Caspase 3, Bax). TUNEL assays revealed an increase in cell apoptosis. Immunohistochemistry staining confirmed the involvement of p53. Conclusion: ZPE decreases AGS cell proliferation and induces apoptosis by inhibiting Akt and MDM2 expression.