Celastrus Orbiculatus Extracts Inhibit the Metastasis through Attenuating PI3K/Akt/mTOR Signaling Pathway in Human Gastric Cancer.

BACKGROUND: Rapamycin receptor inhibitors have been applied in the clinic and achieved satisfactory therapeutic effect recently. The mechanisms did not clearly show how the Celastrus Orbiculatus Extracts (COE) inhibited the expression of the mammalian Target of Rapamycin (mTOR) in human gastric cancer cells. The aim of this study was to investigate whether the COE inhibited the metastasis through the mTOR signaling pathway in human gastric cancer MGC-803 cells. METHODS: The abnormal expression level of mTOR protein was detected by immunohistochemistry in human gastric cancer tissue. The MGC-803/mTOR- cells were constructed by knockdown of mTOR using lentivirus infection technique. The human gastric cancer MGC-803/mTOR- cells were treated with different concentrations (20, 40, 80 µg/ml) of COE for 24 hours. The ability of cell metastasis was analyzed by the cell invasion and migration assay. The expression levels of PI3K/Akt/mTOR signaling pathway were detected by Western Blotting. RESULTS: COE inhibited the proliferation, invasion and migration of MGC-803/mTOR- cells in a concentrationdependent manner. The expression of E-cadherin protein increased, and the expression of N-cadherin and Vimentin decreased simultaneously in the MGC-803/mTOR- cells. 4EBP1, p-4EBP1, P70S6k, p-P70S6k, mTOR, p-mTOR, PI3K and Akt proteins in MGC-803/mTOR- cells were reduced in a dose-dependent manner. CONCLUSION: COE could not only inhibit cell growth, invasion and migration, but also inhibit the epithelialmesenchymal transition of gastric cancer cells. The molecular mechanism of COE inhibited the metastasis which may be related to the PI3K/Akt/mTOR signal pathway. This study provides ideas for the development of new anti-gastric cancer drugs.

Celastrus orbiculatus Extracts Inhibit Human Hepatocellular Carcinoma Growth by Targeting mTOR Signaling Pathways.

OBJECTIVE: To characterize the molecular mechanism underlying the antineoplastic activity of Celastrus orbiculatus Thunb. extracts (COE). METHODS: The human hepatocellular carcinoma HepG2 cells with mammalian target of rapamycin (mTOR) knockdown expressed (HepG2/mTOR) were constructed using molecular biological technology. In vitro, the HepG2/mTOR- cells were treated with COE at various concentrations (10, 20, 40, 80, 160 and 320 µ g/mL). Cell viability was determined using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays. According to the half-maximal inhibitory concentration (IC50) value (140 mg/L), the concentrations of COE in the subsequent experiment was set to alleviate cytotoxicity. The HepG2/mTOR- cells were divided into 5 groups: negative control (untreated), COE treatment groups (40, 80, 120 mg/L COE) and positive control group (cisplatin, DDP, 2 mg/L), respectively. Wild-type HepG2 cells were used as a blank control. The effects of COE on the cell apoptosis were analyzed by flow cytometry and transmission electronic microscopy (TEM), respectively. The protein expression levels of mTOR signal pathways were determined by Western blotting. In vivo, HepG2/mTOR- cells (2 × 106 cell/mice) were subcutaneously injected into the right flank of nude mice. Thirty-six female nude mice were randomly assigned to 6 groups according to body weight (6 mice per group) as follows: solvent vehicle control, Banmao Capsule treated group (BM, 195 mg/kg), Tegafur, Gimeracil and Oteracil Potassium Capsules (10 mg/kg) treated group, and different dosages of COE (10, 20, 40 mg/kg) groups. Tumor growth was monitored and immunohistochemical staining was used to examine the expression of apoptosis-related proteins in tumor tissues. RESULTS: COE inhibited the proliferation significantly in a concentration-dependent manner in HepG2/mTOR- cells (P<0.01). COE significantly induced the apoptosis of HepG2/mTOR- cells (P<0.01), and the apoptotic bodies can be observed under TEM. COE significantly inhibits the proteins expression of mTOR-related signal pathways. In vivo, COE significantly inhibited tumor growth in nude mice (P<0.01). Moreover, the results showed that COE down-regulated the expression of Bcl-2 and Bcl-xL, and up-regulated the levels of Bax and caspase-3 protein (P<0.01). CONCLUSION: COE was a potential chemotherapeutic drug in HCC treatments via targeting mTOR signal pathway.

Celastrus orbiculatus extracts induce apoptosis in mTOR-overexpressed human hepatocellular carcinoma HepG2 cells.

BACKGROUND: Celastrus orbiculatus (Celastraceae) are used as traditional Chinese medicine to treat inflammation and cancer. This study aims to evaluate the effect of Celastrus orbiculatus extract (COE) on the apoptosis in human hepatic carcinoma HepG2 cells with mTOR overexpression. METHODS: The stable expression of mTOR in HepG2 cells (HepG2/mTOR+) were established by lipofectin transfection of GV238-mTOR recombinant plasmids and further antibiotic selection. Human hepatic carcinoma HepG2/mTOR+ cells were treated with different concentrations (20, 40, 80, 160, and 320 µg/mL) of COE for 24 h. The cell proliferation upon COE treatment was detected by MTT. Apoptosis was measured by Flow Cytometry. The activity of mTOR signaling pathway was detected by Western Blotting. RESULTS: COE significantly inhibited the proliferation of HepG2/mTOR+ cells. The expression levels of Bax and Caspase-3 protein were increased in the HepG2/mTOR+ cells in a dose-dependent manner. The proteins expression of Bcl2, Bcl-2 L12, mTOR, phospho-mTOR, 4EBP1, phospho-4EBP1, P70S6k, and phospho-P70S6k in HepG2/mTOR+ cells were reduced in dose-dependent manners. Furthermore, COE and mTOR inhibitor rapamycin (RAPA) synergistically induced apoptosis in HepG2/mTOR+ cells by regulating apoptosis-related proteins and inhibiting mTOR signaling pathways. CONCLUSION: COE could inhibit the proliferation of HepG2/mTOR+ cells, and induce the cell apoptosis. The mechanisms may be related to the regulation of the expression of Bcl-2, Bcl-2 L12, and mTOR signaling pathways. These data suggest that COE may be a potential treatment for human hepatocellular carcinoma.