Chunbo Wang

Effect of Purple Sweet Potato Anthocyanins on β-Amyloid-Mediated PC-12 Cells Death by Inhibition of Oxidative Stress

Amyloid-beta peptide (Aβ) is known to induce the redox imbalance, mitochondrial dysfunction and caspase activation, resulting in neuronal cell death. Treatment with antioxidants provided a new therapeutic strategy for Alzheimer’s disease (AD) patients. Here we investigate the effects of purple sweet potato anthocyanins (PSPA), the known strong free radical scavengers, on Aβ toxicity in PC12 cells. The results showed that pretreatment of PC12 cells with PSPA reduced Aβ-induced toxicity, intracellular reactive oxygen species (ROS) generation and lipid peroxidation dose-dependently. In parallel, cell apoptosis triggered by Aβ characterized with the DNA fragmentation and caspase-3 activity were also inhibited by PSPA. The concentration of intracellular Ca2+ and membrane potential loss associated with cell apoptosis were attenuated by PSPA. These results suggested that PSPA could protect the PC-12 cell from Aβ-induced injury through the inhibition of oxidative damage, intracellular calcium influx, mitochondria dysfunction and ultimately inhibition of cell apoptosis. The present study indicates that PSPA may be a promising approach for the treatment of AD and other oxidative-stress-related neurodegenerative diseases.

Marine lysozyme from a marine bacterium that inhibits angiogenesis and tumor growth.

Recent studies suggest that lysozyme, rich in hen egg, has an antitumor function. In the present study, we investigated the antitumor and antiangiogenesis effects of a newly isolated marine lysozyme both in vitro and in vivo. First, we showed that this marine-derived lysozyme specifically inhibits the proliferation of endothelial cells (ECV304) in a dose-dependent manner with no cytotoxicity (IC50u2009=u20093.64xa0μM). Second, we showed that this marine lysozyme directly suppresses neovascularization in chicken embryos using chorioallantoic membrane assay. Third, we demonstrated that this marine lysozyme markedly inhibits tumor growth in mice bearing either sarcoma 180 or hepatoma 22. Unexpectedly, hen egg lysozyme has no effects on the proliferation of endothelial cells in vitro or neovascularization in chicken embryos or tumor growth in nude mice at the same dosage range. Taken together, our studies clearly show that the newly identified marine lysozyme is a potent antitumor molecule, which may inhibit tumor growth and inhibit angiogenesis. We believe that this marine lysozyme may have a therapeutic value in antitumor drug development.

Cytoprotective effect of polypeptide from Chlamys farreri on neuroblastoma (SH-SY5Y) cells following H2O2 exposure involves scavenging ROS and inhibition JNK phosphorylation

Oxidative stress has long been linked to cell death in many neurodegenerative conditions. Treatment with antioxidants is a promising approach for slowing disease progression. In this study, we used the neuroblastoma SH‐SY5Y cells as an in vitro model to first assess the effect of polypeptide from Chlamys farreri (PCF), a natural marine antioxidant, on H2O2‐induced neuronal cell death. Pre‐treatment of SH‐SY5Y cells with PCF inhibited H2O2‐induced cell death in a concentration‐dependent manner. In parallel, intracellular reactive oxygen species generation and lipid peroxidation were inhibited by PCF. Under severe H2O2 insult, PCF promoted endogenous antioxidant defense components including glutathione peroxidase, catalase, superoxide dismutase, and glutathione. PCF also protected DNA from oxidative damage and enhanced the removal of 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine from DNA. Further, we found that PCF potentially prevented H2O2–induced cell apoptosis. When investigated mitogen‐activated protein kinase signaling pathway, we found that pre‐treatment of cells with PCF significantly blocked H2O2–induced phosphorylation of c‐Jun N‐terminal kinase of the mitogen‐activated protein kinase family. However, PCF had little inhibitory effect on the H2O2–induced activation of extracellular signal‐regulated kinase. Taken together, these data demonstrate that PCF prevents oxidative stress‐induced reactive oxygen species production and c‐Jun N‐terminal kinase activation and may be useful in the treatment of neurodegenerative diseases.

Physcion inhibits the metastatic potential of human colorectal cancer SW620 cells in vitro by suppressing the transcription factor SOX2

Aim:Physcion, an anthraquinone derivative, exhibits hepatoprotective, anti-inflammatory, anti-microbial and anti-cancer activities. In this study we examined whether and how physcion inhibited metastatic potential of human colorectal cancer cells in vitro.Methods:Human colorectal cancer cell line SW620 was tested. Cell migration and invasion were assessed using a wound healing and Transwell assay, respectively. The expression levels of transcription factor SOX2 in the cells were modulated with shRNA targeting SOX2 and SOX2 overexpressing plasmid. The expression of target molecules involved in epithelial-mesenchymal transition (EMT) process and the signaling pathways was determined with Western blots or qRT-PCR. ROS levels were measured using DCF-DA.Results:Physcion (2.5, 5 mol/L) did not affect the cell viability, but dose-dependently inhibited the cell adhesion, migration and invasion. Physcion also inhibited the EMT process in the cells, as evidenced by the increased epithelial marker E-cadherin expression, and by decreased expression of mesenchymal markers N-cadherin, vimentin, fibronectin and α-SMA, as well as transcriptional repressors Snail, Slug and Twist. Physcion suppressed the expression of SOX2, whereas overexpression of SOX2 abrogated the inhibition of physcion on metastatic behaviors. Physcion markedly increased ROS production and phosphorylation of AMPK and GSK3β in the cells, whereas the AMPK inhibitor compound C or the ROS inhibitor NAC abolished the inhibition of physcion on metastatic behaviors.Conclusion:Physcion inhibits the metastatic potential of human colorectal cancer cells in vitro via activating ROS/AMPK/GSK3β signaling pathways and suppressing SOX2.

Inhibitory effect of polypeptide from Chlamys farreri on UVA-induced apoptosis in human keratinocytes.

Polypeptide from Chlamys farreri (PCF, Mr = 879) is a novel marine active product isolated from gonochoric Chinese scallop Chlamys farreri which has been served as sea food for several thousand years. As an octapeptide, PCF consists of 8 amino acids, namely, Pro, Asn, Ser, Thr, Arg, Hyl, Cys, and Gly. PCF had been identified as a marine chemopreventive drug that protected hairless mices epidermis against UV-induced damage in our previous study. However, the molecular mechanisms that underlie the effect of PCF on ultraviolet A-induced apoptosis in ketatinocytes are not well understood yet. In the present study, PCF was investigated as a potential inhibitory agent for UVA-induced apoptosis in a human keratinocyte cell line, HaCaT. The effects of PCF on UVA-induced generation of ROS and MDA, DNA damage, apoptosis rate were examined. We also investigated whether PCF could inhibit UVA-induced decreasing of mitochondrial membrane potential and the changing of morphology of the cells. We found that, compared with UVA only group, PCF attenuated UVA-induced generation of ROS and MDA, increased the mitochondrial membrane potential, and decreased the apoptosis rate. These results indicate that PCF may protect HaCaT keratinocytes against UVA-induced apoptosis.

Purple sweet potato pigments protect murine thymocytes from 60Co γ-ray-induced mitochondria-mediated apoptosis

Purpose:u2003Purple sweet potato (PSP) pigments have been widely accepted as antioxidants but their radioprotective effect still remains unclear. In this study we investigated the effect of PSP pigments on 60Co γ-ray-induced mitochondria-mediated apoptosis in murine thymocytes. Materials and methods:u2003The murine thymocytes were pretreated by PSP pigments before exposure to 4 Gy 60Co γ-rays. Flow cytometry analysis was used to measure apoptotic cells and mitochondrial membrane potential. Reactive oxygen species (ROS) were detected using 2′,7′,-dichlorofluorescein diacetate (DCFH-DA) probe and the activity of antioxidant enzymes was tested by biochemical assay after irradiation. Cytochrome c, caspase-3 and poly ADP-ribose polymerase (PARP) were measured by Western blotting. Results:u2003After treatment with PSP pigments and exposure to 4 Gy radiation the apoptosis of thymocytes was reduced and the mitochondrial transmembrane potential was maintained compared to control cells. In the presence of PSP pigments, ROS were reduced and the activities of glutathione peroxidase (GSH-px) and superoxide dismutase (SOD) were protected and in some cases increased. All the pro-apoptotic proteins (cytochrome oxidase, caspase 3 and PARP) decreased in PSP pigments pretreated thymocytes compared to irradiated cells in the absence of PSP pigments. Conclusions:u2003Pre-treatment with PSP pigments significantly inhibited 60Co γ-ray-induced mitochondria-mediated apoptosis. This radioprotective effect might be related to ROS scavenging, the enhancement of the activity of antioxidant enzymes, the maintenance of mitochondrial transmembrane potential, and the sequential inhibition of cytochrome c release and downstream caspase and PARP cleavage.

Polypeptide from Chlamys farreri attenuates murine thymocytes damage induced by ultraviolet B.

AbstractAim:Polypeptide from Chlamys farreri (PCF, molecular mass is 879) is a new marine polypeptide compound isolated from Chlamys farreri. This study investigates the possible protective roles and the mechanism of PCF against ultraviolet B (UVB)-induced apoptosis in murine thymocytes.Methods:The rate of apoptosis and caspase-3 activation was measured by flow cytometry. The expression of stress-response genes c-fos and c-jun was observed by RT—PCR. Western blot analysis was performed to determine the release of cytochrome c.Results:It was found that UVB induced murine thymocyte death. The cells treated with UVB showed an increase in cytochrome c release, caspase-3 activity, as well as in the expression of c-fos and c-jun. In addition, all were involved in UVB-induced cell apoptosis.Conclusion:Our present observations pointed to the ability of PCF to avert UVB-induced apoptosis in thymocytes by modulating c-fos and c-jun expression, cytochrome c release, and the consequent activation of caspase-3, which were essential components of the UV-induced cell apoptotic pathway. The results suggested that PCF is a promising protective substance against UV radiation.

In vitro anti— irradiation effects of a polypeptide from Chlamys farreri

ObjectiveTo investigate the anti—irradiation effects of a polypeptide fromChlamys farreri (PCF) on y-ray induced damage to mouse thymocytes.MethodsThymocytes were randomly divided into 6 groups including an untreated control, a model group, groups treated with 5, 2.5 and 1.25 mg PCF/ml and a 0.1% vitamin C group. Cell viability, morphology, nucleic acid and enzymatic changes of the cells 3 h after 3 Gy γ—ray irradiation at a dose rate of 0.6 Gy/min were determined.Resultsγ— Fiay irradiation decreased the cell viability and SOD activity and increased MDA levels and the apoptotic number of cells. PCF increased cell viability and SOD activity and decreased MDA levels and the apoptotic number of the cells in a dose-dependant manner.ConclusionPCF pretreatment can attenuate cytotoxicity, inhibit apoptosis, reduce the level of MDA and maintain the activity of SOD. Therefore PCF has anti—irradiation effects on γ—ray induced damage of mouse thymocytes.