Lycopene inhibits growth of human colon cancer cells via suppression of the Akt signaling pathway

The aberrant regulation of the phosphoinositide 3-kinase/Akt survival signaling pathway in cancer has prompted significant interest in suppression of this pathway to treat cancer. Previous studies identified an important role for phosphoinositide 3-kinase/Akt in colon cancer progression. Lycopene, a major component in tomato, exhibited potential anti-carcinogenic activity. Consumption of tomato has been associated with reduced risk of several types of human cancer. However, the inhibitory mechanisms of lycopene on the proliferation of human colon cancer have not been studied well yet. Thus we investigated the inhibitory effects of lycopene on the Akt signaling pathway in human colon cancer HT-29 cells. Lycopene inhibited cell proliferation in human colon cancer HT-29 cells with a IC(50) value of 10 microM. Lycopene treatment suppressed Akt activation and non-phosphorylated beta-catenin protein level in human colon cancer cells. Immunocytochemical results indicated that lycopene increased the phosphorylated form of beta-catenin proteins. These effects were also associated with reduced promoter activity and protein expression of cyclin D1. Furthermore, lycopene significantly increased nuclear cyclin-dependent kinase inhibitor p27(kip)abundance and inhibited phosphorylation of the retinoblastoma tumor suppressor protein in human colon cancer cells. In conclusion, lycopene inhibited cell proliferation of human colon cancer cells via suppression of the Akt signaling pathway and downstream targeted molecules.     

Modulation of the superoxide anion production and MMP-9 expression in PMA stimulated THP-1 cells by olive oil minor components: Tyrosol and hydroxytyrosol

Extra virgin olive oil has been associated with a reduced incidence of risk factors for coronary heart disease also owing to the presence of antioxidant biophenols. Reactive oxygen species (ROS) and matrix metalloproteinase-9 (MMP-9) have been implicated in numerous somatic illnesses, including cardiovascular disorders and cancer. The aim of this work was to study the capacity of virgin olive oil tyrosol (T) and hydroxytyrosol (HT) at impairing superoxide production and MMP-9 expressions in monocyte cells (THP-1) conveniently differentiated into adherent macrophages, taken as a model of human macrophages implicated in atheroma.O₂⁻ production was evaluated in THP-1 cells by using lucigenin as a specific chemiluminescent probe. Cells, after differentiation for 72 h, were preincubated in the presence of HT and T at increasing concentrations for 4, 15 and 24 h, and then, monocyte-like cells were stimulated by phorbol myristate acetate (PMA) and the O₂⁻-dependent luminescence was immediately recorded at 37 °C by means of a Luminometer. Enzymatic activity of MMP-9 derived from a medium of cells preincubated, or not, with T or HT was tested by zymography.As compared to the cells without treatment, cells preincubated with HT, showed a decrease of O₂⁻ production (50%) at 1 ??M for 15 h of preincubation time. Tyrosol fully prevented ROS overproduction at 15 h and, like HT displayed a high degree of protection but at higher concentrations and later time points (24 h). Gelatin zymograms revealed a reduction of the expression of MMP-9 in conditioned medium derived from T and HT-treated cells. These findings give further evidence in favour of olive oil consumption to counteract cardiovascular diseases.     

Tannin 1-alpha-O-galloylpunicalagin induces the calcium-dependent activation of endothelial nitric-oxide synthase via the phosphatidylinositol 3-kinase/Akt pathway in endothelial cells

Many polyphenols have been found to increase endothelial nitric oxide (NO) production. In our present study, we investigated the effects of 1-alpha-O-galloylpunicalagin upon endothelial nitric oxide synthase (eNOS) activity in endothelial cells (ECs). Both 1-alpha-O-galloylpunicalagin and punicalagin induced NO production in a dose-dependent manner in ECs. Despite having similar chemical structures, punicalagin induced lower levels of NO production than 1-alpha-O-galloylpunicalagin. After 1-alpha-O-galloylpunicalagin addition, a rise in the intracellular Ca(2+) concentration preceded NO production. The Ca(2+) ionophore A23187 stimulated eNOS phosphorylation and augmented NO production. Pretreatment with Ca(2+) chelators inhibited 1-alpha-O-galloylpunicalagin-induced eNOS phosphorylation and NO production. Treatment with 1-alpha-O-galloylpunicalagin did not alter the eNOS protein levels but, unlike punicalagin, induced a sustained activation of eNOS Ser(1179) phosphorylation. 1-alpha-O-galloylpunicalagin was also found to activate ERK1/2, JNK and Akt in ECs. Moreover, simultaneous treatment of these cells with specific phosphatidylinositol-3-kinase inhibitors significantly inhibited the observed increases in eNOS activity and phosphorylation levels. In contrast, the inhibition of (ERK)1/2, JNK and p38 had no influence on eNOS Ser(1179) phosphorylation. Our present results thus indicate that the 1-alpha-O-galloylpunicalagin-induced calcium-dependent activation of eNOS is primarily mediated via a phosphatidylinositol 3-kinase/Akt-dependent increase in eNOS activity, and occurs independently of the eNOS protein content.     

Ursolic acid,a naturally occurring triterpenoid,suppresses migration and invasion of human breast cancer cells by modulating c‐Jun N‐terminal kinase,Akt and mammalian target of rapamycin signaling

Metastasis is one of the most important factors related to breast cancer therapeutic efficacy. Ursolic acid, a naturally occurring triterpenoid, has various anticancer activities. In this study, we first observed that ursolic acid exerted a dose‐ and time‐dependent inhibitory effect on the migration and invasion of highly metastatic breast MDAMB231 cells at non‐cytotoxic concentrations. This effect was associated with reduced activities of metalloproteinase‐2 (MMP‐2) and u‐PA, which correlated with enhanced expression of tissue inhibitor of MMP‐2 and plasminogen activator inhibitor‐1, respectively. Ursolic acid suppressed the phosphorylation of Jun N‐terminal kinase, Akt and mammalian target of rapamycin, but had no effect on the phosphorylation of ERK and p38. Ursolic acid also strongly reduced the levels of NFκB p65, c‐Jun and c‐Fos proteins in the nucleus of MDAMB231 cells. A time‐dependent inhibition of the protein levels of Rho‐like GTPases, growth factor receptor‐bound protein 2, Ras and vascular endothelial growth factor in cytosol by ursolic acid treatment was also observed. In conclusion, we demonstrated that the anti‐invasive effects of ursolic acid on MDAMB231 cells might be through the inhibition of Jun N‐terminal kinase, Akt and mammalian target of rapamycin phosphorylation and a reduction of the level of NFκB protein in the nucleus, ultimately leading to downregulation of MMP‐2 and u‐PA expression. These results suggest that ursolic acid has potential as a chemopreventive agent for metastatic breast cancer.     

Suppression of EGF-induced tumor cell migration and matrix metalloproteinase-9 expression by capsaicin via the inhibition of EGFR-mediated FAK/Akt, PKC/Raf/ERK, p38 MAPK, and AP-1 signaling

Scope: Capsaicin is a cancer‐suppressing agent. The aim of our study was to determine the effect of capsaicin on tumor invasion and migration; the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma cells. Methods and results: We employed invasion, migration and gelatin zymography assays to characterize the effect of capsaicin on HT‐1080 cells. Transient transfection assays and immunoblot analysis were performed to study its molecular mechanisms of action. Capsaicin inhibited the epidermal growth factor (EGF)‐induced activation of matrix metalloproteinase (MMP)‐9 and MMP‐2, and further inhibited cell invasion and migration. Capsaicin decreased the EGF‐induced expression of MMP‐9, MMP‐2, and MT1‐MMP, but did not alter TIMP‐1 and TIMP‐2 levels. Capsaicin suppressed EGF‐induced c‐Jun and c‐Fos nuclear translocation, and also abrogated the EGF‐induced phosphorylation of EGF receptor (EGFR), focal adhesion kinase (FAK), protein kinase C (PKC), phosphatidylinositol 3‐Kinase (PI3K)/Akt, extracellular regulated kinase (ERK)1/2, and JNK1/2, an upstream modulator of AP‐1. Furthermore, the EGFR inhibitor inhibited EGF‐induced MMP‐9 expression, as well as AP‐1 activity and cell migration. Conclusion: Capsaicin inhibited the EGF‐induced invasion and migration of human fibrosarcoma cells via EGFR‐dependent FAK/Akt, PKC/Raf/ERK, p38 mitogen‐activated protein kinase (MAPK), and AP‐1 signaling, leading to the down‐regulation of MMP‐9 expression. These results indicate the role of capsaicin as a potent anti‐metastatic agent, which can markedly inhibit the metastatic and invasive capacity of fibrosarcoma cells.     

Anti-inflammatory effect of the hexane fraction from Orostachys japonicus in RAW 264.7 cells by suppression of NF-κB and PI3K-Akt signaling

We investigated the anti-inflammatory effect of the hexane fraction from Orostachys japonicus (OJH) in LPS (lipopolysaccharide)-stimulated RAW 264.7 cells. Pretreatment with OJH dose-dependently reduced the cellular NO (nitric oxide) concentration and also inhibited expression of iNOS (inducible nitric oxide synthase) protein and mRNA. By the prevention of IκBα (inhibitory factor kappa B alpha) phosphorylation and degradation, OJH inhibited LPS-induced NF-κB (nuclear factor-kappa B) activation. OJH had no effect on the LPS-induced phosphorylation of ERK (extracellular signal-regulated kinase), JNK (c-Jun N-terminal kinase), or p38, whereas it attenuated the phosphorylation of Akt in a dose-dependent manner. In addition, OJH suppressed the LPS-induced expression of LPS receptors CD14 and TLR4 (toll like receptor 4). These results suggest that OJH may interrupt LPS-induced pro-inflammatory cascades through inhibition of NF-κB and Akt activation.     

Sesamin attenuates intercellular cell adhesion molecule‐1 expression in vitro in TNF‐α‐treated human aortic endothelial cells and in vivo in apolipoprotein‐E‐deficient mice

Sesame lignans have antioxidative and anti‐inflammatory properties. We focused on the effects of the lignans sesamin and sesamol on the expression of endothelial‐leukocyte adhesion molecules in tumor necrosis factor‐α (TNF‐α)‐treated human aortic endothelial cells (HAECs). When HAECs were pretreated with sesamin (10 or 100 μM), the TNF‐α‐induced expression of intercellular cell adhesion molecule‐1 (ICAM‐1) was significantly reduced (35 or 70% decrease, respectively) by Western blotting. Sesamol was less effective at inhibiting ICAM‐1 expression (30% decrease at 100 μM). Sesamin and sesamol reduced the marked TNF‐α‐induced increase in human antigen R (HuR) translocation and the interaction between HuR and the 3'UTR of ICAM‐1 mRNA. Both significantly reduced the binding of monocytes to TNF‐α‐stimulated HAECs. Sesamin significantly attenuated TNF‐α‐induced ICAM‐1 expression and cell adhesion by downregulation of extracellular signal‐regulated kinase 1/2 and p38. Furthermore, in vivo, sesamin attenuated intimal thickening and ICAM‐1 expression seen in aortas of apolipoprotein‐E‐deficient mice. Taken together, these data suggest that sesamin inhibits TNF‐α‐induced extracellular signal‐regulated kinase/p38 phosphorylation, nuclear translocation of NF‐κB p65, cytoplasmic translocalization of HuR and thereby suppresses ICAM‐1 expression, resulting in reduced adhesion of leukocytes. These results also suggest that sesamin may prevent the development of atherosclerosis and inflammatory responses.