Inhibitory effects of petasin on human colon carcinoma cells mediated by inactivation of Akt/mTOR pathway.

BACKGROUND: Colorectal cancer is the third most common cancer worldwide and still lack of effective therapy so far. Petasin, a natural product found in plants of the genus Petasites, has been reported to possess anticancer activity. The present study aimed to investigate the anticolon cancer activity of petasin both in vitro and in vivo. The molecular mechanism of petasin was also further explored. METHODS: Caco-2, LoVo, SW-620, and HT-29 cell lines were used to detect the inhibitory effect of petasin on colon cancer proliferation. Cell viability was determined using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Cell apoptosis was analyzed by flow cytometry. Hoechst 33258 staining was used to visualize morphological changes. Cell migration was assessed using a wound-healing migration assay, and cell invasion was investigated using Transwell chambers. Western blotting assays were employed to evaluate the expression levels of proteins in the protein kinase B/mammalian target of rapamycin (Akt/mTOR) signaling pathway. Finally, in vivo activity of petasin was evaluated using the SW-620 subcutaneous tumor model established in Balb/c nude mice. Twelve rats were randomly divided into control group and 10 mg/kg petasin group. The tumor volume was calculated every 7 days for 28 days. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay was performed to assess the apoptotic effect of petasin. Differences between two groups were assessed by analysis of independent-sample t tests. RESULTS: Petasin significantly inhibited the proliferation of human colon carcinoma cell lines, induced apoptosis, and suppressed migration and invasion in SW-620 cells. Western blotting results showed that petasin decreased the phosphorylation of Akt (1.01 ±â€Š0.16 vs. 0.74 ±â€Š0.06, P = 0.042), mTOR (0.71 ±â€Š0.12 vs. 0.32 ±â€Š0.11, P = 0.013), and P70S6K (1.23 ±â€Š0.21 vs. 0.85 ±â€Š0.14, P = 0.008), elevated the expression of caspase-3 (0.41 ±â€Š0.09 vs. 0.74 ±â€Š0.12, P = 0.018) and caspase-9 (1.10 ±â€Š0.27 vs. 1.98 ±â€Š0.22, P = 0.009), decreased the Bcl-2 protein (2.75 ±â€Š0.47 vs. 1.51 ±â€Š0.36, P = 0.008), downregulated the expression of matrix metalloproteinase (MMP)-3 (1.51 ±â€Š0.31 vs. 0.82 ±â€Š0.11, P = 0.021) and MMP-9 (1.56 ±â€Š0.32 vs. 0.94 ±â€Š0.15, P = 0.039) in SW-620 cell. In vivo, 10 mg/kg petasin inhibited tumor growth in Balb/c nude mice (924.18 ±â€Š101.23 vs. 577.67 ±â€Š75.12 mm at day 28, P = 0.001) and induced apoptosis (3.6 ±â€Š0.7% vs. 36.0 ±â€Š4.9%, P = 0.001) in tumor tissues. CONCLUSIONS: Petasin inhibits the proliferation of colon cancer SW-620 cells via inactivating the Akt/mTOR pathway. Our findings suggest petasin as a potential candidate for colon cancer therapy.

Euphornin reduces proliferation of human cervical adenocarcinoma HeLa cells through induction of apoptosis and G2/M cell cycle arrest.

BACKGROUND: The plant Euphorbia helioscopia L. has been used in traditional Chinese medicine for treating various disorders such as tuberculosis and edema. The aim of this study was to investigate the effect of euphornin, a bioactive compound isolated from E. helioscopia, on proliferation of human cervical adenocarcinoma HeLa cells by analyzing cell viability, rate of apoptosis, and cell cycle progression. MATERIALS AND METHODS: The sulforhodamine B assay was used to study the effect of euphornin on the proliferation of HeLa cells. Morphological changes to cell nuclei were identified after Hoechst 33342 staining. Mitochondrial membrane depolarization (MMP) was analyzed after staining with JC-1 dye. The influence of euphornin on the apoptosis rate was analyzed by Annexin V/propidium iodide double staining. Fluorescence-activated cell sorting was applied to investigate the influence of euphornin on cell cycle progression. Proteins were obtained from HeLa cells and analyzed by Western blots. RESULTS: A cell viability assay showed that euphornin inhibited proliferation of HeLa cells in a dose-dependent and time-dependent manner. Euphornin also induced apoptosis in a concentration-dependent manner, with the rates of apoptosis ranging from 25.3% to 52.6%. A high concentration of euphornin was found to block HeLa cells at the G2/M stage. A Western blot analysis suggested that euphornin might exhibit antitumor activity by inducing apoptosis. Euphornin treatment altered the ratio of Bax/Bcl-2 in HeLa cells, which led to the release of cytochrome complex. The levels of cleaved caspase-3, caspase-8, caspase-9, and caspase-10 were also markedly increased by euphornin treatment. Analysis of cell cycles indicated that euphornin induced cell cycle arrest by increasing the level of the phospho-CDK1 (Tyr15) protein. The various assays demonstrated that euphornin treatment resulted in a significant suppression of cell growth accompanied by G2/M cell cycle arrest and increased rate of apoptosis via mitochondrial and caspase pathways. CONCLUSION: Our findings suggest that euphornin has the potential to be used as a cancer therapeutic agent against human cervical adenocarcinoma.

In vitro study of the cytotoxicities of two mixed-ligand oxovanadium complexes on human hepatoma cells.

The cytotoxicities of two oxovanadium complexes, VOI [VO(satsc)(phen)] (satsc = salicylaldehyde thiosemicarbazone, phen = 1,10-phenanthroline) and VOII [VO(3,5-dibrsatsc)(phen)](3,5-dibrsatsc = 3,5-dibromosalicylaldehyde thiosemicarbazone), were studied by performing MTT assays on human hepatoma cell lines BEL-7402, HUH-7 and HepG2. The results showed that both the VOI and VOII complexes possess significant anti-proliferative effects. In addition, the anti-proliferative mechanism of the complexes was analyzed by cell cycle analysis and an apoptosis assay and by detecting the mitochondrial membrane potential (delta psi m). The experimental results showed that the complexes can cause a G0/G1 phase cell cycle arrest and can significantly decrease delta psi m, causing depolarization of the mitochondrial membrane. Notably, the two complexes induced apoptosis in BEL-7402 cells and displayed typical morphological apoptotic characteristics. The cytotoxicities of the VOII complex are significantly stronger than that of the VOI complex, suggesting that the cytotoxic effects of oxovanadium complexes may be associated with the electronic effects of the complexes.

A comparison of the effects of digoxin, ouabain and milrinone on naloxone-precipitated withdrawal syndrome in mice.

Modulation of Na(+), K(+)-ATPase activity by acute and chronic opiates has been established for many years. However, the effects of digoxin, a putative inhibitor of Na(+), K(+)-ATPase, on naloxone-precipitated morphine withdrawal syndrome are unknown. In the present study, a digoxin dose-response curve was conducted to observe the effects on naloxone-precipitated withdrawal and locomotor activity in mice. Higher doses of digoxin (1.0 and 2.5 mg/kg) inhibited locomotor activity and naloxone-precipitated withdrawal jumping and weight loss, while lower doses of digoxin (0.1 and 0.25 mg/kg) inhibited withdrawal weight loss precipitated by naloxone without affecting locomotor activity and naloxone-precipitated withdrawal jumping. To explore the possible mechanisms underlying this behavior, another Na(+), K(+)-ATPase inhibitor ouabain, which does not cross the blood brain barrier, and another cardiotonic drug milrinone, a non-inhibitor of Na(+), K(+)-ATPase, were also included in the present study. Both milrinone and ouabain inhibited, in a dose-dependent manner, naloxone-precipitated weight loss while neither affected naloxone-precipitated withdrawal jumping nor locomotor activity in mice. These results indicate that both the cardiotonic effects and central inhibition of Na(+), K(+)-ATPase contribute to the inhibitory effects of digoxin on morphine withdrawal syndrome in mice.