Wen-Juan Li

(−)-Epigallocatechin-3-gallate Induces Apoptosis of Human Hepatoma Cells by Mitochondrial Pathways Related to Reactive Oxygen Species

The aim of this study was to investigate the effects of (-)-epigallocatechin-3-gallate (EGCG) on the induction of apoptosis in hepatocarcinoma cell lines in vitro and further examine the molecular mechanisms of EGCG-induced apoptosis. In the present study, it was observed that EGCG rapidly induced apoptosis in hepatocarcinoma SMMC7721 cells. EGCG-induced apoptosis was in association with the attenuation of mitochondrial transmembrane potentials (Deltapsi(m)), the alteration of Bcl-2 family proteins, the release of cytochrome c from mitochondria into the cytosol, and the activation of caspase-3 and caspase-9. Elevation of intracellular reactive oxygen species (ROS) production was also shown during EGCG-induced apoptosis of hepatocarcinoma SMMC7721 cells. The antioxidant N-acetyl-l-cysteine (NAC) significantly reduced ROS production and EGCG-induced apoptosis, suggesting that ROS plays a key role in EGCG-induced apoptosis in hepatocarcinoma SMMC7721 cells. In summary, EGCG-induced apoptosis through mitochondrial pathways, and ROS affected EGCG-induced apoptosis in hepatocarcinoma SMMC7721 cells.

Immunomodulatory effect of Ganoderma atrum polysaccharide on CT26 tumor-bearing mice

Ganoderma atrum has attracted great attention for its antitumor activity. However, the mechanism remains unclear. A G. atrum polysaccharide (PSG-1) showed pronounced antitumor activity in this study. PSG-1 did not kill CT26 cells directly, but inhibited the proliferation of CT26 cells via the activation of peritoneal macrophages (MΦ). In vivo, PSG-1 significantly suppressed the tumor growth in CT26 tumor-bearing mice. The treatment caused a significant increase in the immune organ index and the phagocytosis of macrophages. The production of TNF-α, IL-1β and nitric oxide also increased. Furthermore, we found that PSG-1 acted on Toll-like receptor (TLR) 4, signaled through p38 MAPK pathway, then activated NF-κB and stimulated TNF-α production. We further found that PSG-1 increased the expression of TLR4 and NF-κB, the degradation of IκBα and the phosphorylation of p38 MAPK. In summary, we have demonstrated that PSG-1 could activate macrophages via TLR4-dependent signaling pathways, improve immunity and inhibit tumor growth.

Enhancement of Cyclophosphamide-Induced Antitumor Effect by a Novel Polysaccharide from Ganoderma atrum in Sarcoma 180-Bearing Mice

The aim of this study was to investigate the enhancement of Ganoderma atrum polysaccharide (PSG-1) on cyclophosphamide (CTX)-induced antitumor effect in sarcoma 180 (S-180)-bearing mice. Results showed that both CTX and PSG-1 delayed tumor growth and resulted in tumor apoptosis. The combined regimen was superior to either modality alone. Moreover, the combined treatment-induced apoptosis was mediated via mitochondrial pathway, as evidenced by alterations of Bcl-2 family proteins, loss of mitochondrial membrane potential (Δψ(m)), cytochrome c release, and caspases activation. Our results also showed that thymus and spleen indexes, lymphocytes proliferation, and concentrations of cytokine in the CTX group were decreased, which were alleviated by PSG-1. Additionally, the combined treatment ameliorated oxidative stress as compared with CTX alone. Taken together, we conclude that PSG-1 improved the antitumor effect of CTX, possibly in part mediated by enhancing the induction of apoptosis via mitochondrial pathways, activating host immune function, and modifying the redox system in S-180-bearing mice.

Macrophage Immunomodulatory Activity of a Purified Polysaccharide Isolated from Ganoderma atrum

The objective of this study was to evaluate the immunomodulatory effects of the purified Ganoderma atrum polysaccharide (PSG‐1) on murine macrophage cell line RAW264.7. Phagocytotic assay by fluorescein isothiocyanate‐dextran internalization showed that PSG‐1 stimulated the phagocytosis of macrophages. G. atrum polysaccharide increased the production of NO, and the level of mRNA expression of inducible nitric oxide synthase in a dose–response manner. G. atrum polysaccharide also dose‐dependently induced the release of TNF‐α and interleukin‐1β. Generation of reactive oxygen species was promoted by PSG‐1, as determined by flow cytometry. Moreover, PSG‐1 induced nuclear factor‐κB activation by elevation of p65 nuclear translocation, suggesting that PSG‐1 probably stimulated macrophage activities by activating the nuclear factor‐κB pathway. Copyright

Ganoderma atrum polysaccharide induces anti‐tumor activity via the mitochondrial apoptotic pathway related to activation of host immune response

Ganoderma atrum polysaccharide (PSG‐1), the major active ingredient isolated from Ganoderma atrum, has been suggested as a candidate for cancer therapy. The aim of this study was to investigate the anti‐tumor effect of PSG‐1 using sarcoma 180 (S‐180) transplanted mice and further to examine the molecular mechanisms of PSG‐1‐induced anti‐tumor effect. Results showed that PSG‐1 significantly inhibited tumor growth in S‐180‐bearing mice. PSG‐1‐induced tumor apoptosis was associated with the alteration of Bcl‐2 family proteins, increase of reactive oxygen species generation, loss of mitochondrial membrane potential (Δψm), release of cytochrome c from the mitochondria into cytosol, and activation of caspase‐3 and ‐9. Elevation of immune function was also shown during PSG‐1‐induced tumor apoptosis, as evidenced by increase of spleen and thymus indexes, lymphocyte proliferation, concentrations of tumor necrosis factor (TNF)‐α, and interleukin‐2 in serum. Furthermore, the combined treatment of PSG‐1 and cyclophosphamide (CTX) results in an enhancement of the anti‐tumor effect of CTX alone via increased host immune response. These results suggested that PSG‐1 had a potent anti‐tumor activity by induction of tumor apoptosis through mitochondrial pathways, and immunoenhancement effect of PSG‐1 was related to its anti‐tumor effect. In addition, PSG‐1 enhanced CTX‐induced anti‐tumor activity in S‐180‐bearing mice. J. Cell. Biochem. 112: 860–871, 2011.

A newly identified polysaccharide from Ganoderma atrum attenuates hyperglycemia and hyperlipidemia

A polysaccharide from Ganoderma atrum (PSG-1) was purified and characterized, and its hypoglycemic and hypolipidemic effects were investigated in high fat diet- and streptozotocin-induced type 2 diabetic rats. Oral administration of PSG-1 at 200 or 400 mg/kg body weight significantly reduced fasting blood glucose and serum insulin levels. PSG-1 significantly decreased the levels of serum total cholesterol, triglyceride, low-density lipoprotein cholesterol, free fatty acid and insulin resistance, and increased high-density lipoprotein cholesterol level and insulin sensitivity. In addition, PSG-1 inhibited the expression of pro-apoptotic protein, Bax and increased the expression of anti-apoptotic protein, Bcl-2 in pancreatic cells, suggesting that PSG-1 exerted a protective role in the pancreas of diabetic rats. These results indicated that PSG-1 may have a potential for the treatment of hyperglycemia, hyperlipidemia, hyperinsulinemia and insulin resistance in type 2 diabetes.

Ganoderma atrum polysaccharide protects cardiomyocytes against anoxia/reoxygenation-induced oxidative stress by mitochondrial pathway.

It is now well established that oxidative stress plays a causative role in the pathogenesis of anoxia/reoxygenation (A/R) injury. Ganoderma atrum polysaccharide (PSG‐1), the most abundant component isolated from G. atrum, has been shown to possess potent antioxidant activity. The goals of this study were to investigate the effect of PSG‐1 against oxidative stress induced by A/R injury and the possible mechanisms in cardiomyocytes. In this work, primary cultures of neonatal rat cardiomyocytes pretreated with PSG‐1 were subjected to A/R and subsequently monitored for cell viability by the 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) assay. The levels of intracellular reactive oxygen species (ROS), apoptosis, and mitochondrial membrane potential (Δψm) were determined by flow cytometry. Western blot analysis was used to measure the expression of cytochrome c, Bcl‐2 family, and manganese superoxide dismutase (MnSOD) proteins, and the activities of caspase‐3 and caspase‐9 were determined by a colorimetric method. The results showed that PSG‐1 protected against cell death caused by A/R injury in cardiomyocytes. PSG‐1 reduced the A/R‐induced ROS generation, the loss of mitochondrial membrane potential (Δψm), and the release of cytochrome c from the mitochondria into cytosol. PSG‐1 inhibited the A/R‐stimulated activation of caspase‐9 and caspase‐3 and alteration of Bcl‐2 family proteins. Moreover, PSG‐1 significantly increased the protein expression of MnSOD in cardiomyocytes. These findings suggest that PSG‐1 significantly attenuates A/R‐induced oxidative stress and improves cell survival in cardiomyocytes through mitochondrial pathway. J. Cell. Biochem. 110: 191–200, 2010.

A major green tea component, (-)-Epigallocatechin-3-gallate, ameliorates doxorubicin-mediated cardiotoxicity in cardiomyocytes of neonatal rats.

Cardiac injury is a major complication of the oxidative stress-generating anticancer drug doxorubicin (DOX). The green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) has been reported to play a cardioprotective role in diseases associated with oxidative stress. The objective of this study was to investigate whether EGCG can protect against DOX-induced toxicity in cardiomyocytes. The data showed that EGCG protected the cardiomyocytes from DOX-mediated cardiotoxicity, as evidenced by decreased lactate dehydrogenase (LDH) activity and increased cell viability in a dose-dependent manner. EGCG treatment also decreased malondialdehyde content and increased protein expression and activities of manganese superoxide dismutase (MnSOD), catalase, and glutathione peroxidase. Furthermore, treatment with EGCG decreased reactive oxygen species (ROS) production and apoptosis. This study suggests that EGCG could protect cardiomyocytes from DOX-induced oxidative stress by attenuating ROS production, apoptosis, and increasing activities and protein expression of endogenous antioxidant enzymes.

Chemoprotective effects of Ganoderma atrum polysaccharide in cyclophosphamide-induced mice

In this study, the chemoprotective effects of Ganoderma atrum polysaccharide (PSG-1) in cyclophosphamide (Cy) treated mice were investigated. In Cy-treated mice, PSG-1 treatment accelerated recovery dose-dependently of peripheral red blood cells, white blood cells and platelets, enhanced splenic natural killer cell activity and cytotoxic T lymphocyte activity. In addition, PSG-1 elevated CD4(+) T lymphocyte counts as well as the CD4(+)/CD8(+) ratio dose-dependently. Furthermore, PSG-1 restored the levels of IL-2, INF-γ, IL-10, IgA, IgM and IgG, as well as hemolysin in the sera. Finally, PSG-1 can also significantly increase the total antioxidant capacity, activities of superoxidase dismutase, catalase and glutathione peroxidase, and decrease the malondialdehyde level in vivo. These findings indicate that PSG-1 plays an important role in the protection against myelosuppression and immunosuppression and oxidative stress in Cy-treated mice and could be a potential immunomodulatory agent.

Sulfated polysaccharides from Cyclocarya paliurus reduce H2O2-induced oxidative stress in RAW264.7 cells

In this study, two sulfated polysaccharides (S-CP1-4 and S-CP1-8) from Cyclocarya paliurus were produced by chlorosulfonic acid-pyridine method. Hydrogen peroxide (H2O2) was used to develop an oxidative stress model in the mouse macrophage cell line RAW264.7. Effects of the two sulfated polysaccharides on H2O2-induced oxidative stress were investigated. The results showed that S-CP(1-8) improved the viability of the H2O2-induced stressed RAW264.7 cells, as well as inhibited the lipid oxidation as determined by the level of malondialdehyde (MDA). Meanwhile, treatment with S-CP(1-4) increased superoxide dismutase (SOD) activity in these cells. The sulfated polysaccharides were found to have a better protective effect against H2O2-induced oxidative stress as compared to the native polysaccharide. Scanning electron microscopy also showed a significant change in the surface morphology of sulfated polysaccharides, but the degradation of main chain of polysaccharides was unconspicuous according to the results of monosaccharide composition. In addition, the sulfated polysaccharides had noticeable DPPH radical scavenging activity. In summary, our results demonstrated that H2O2 was able to induce oxidative stress in RAW264.7 cells, and sulfated group might play an important role in resistance to H2O2-induced oxidative damage.