Geun-Tae Park

The neuroprotective effects of cordycepin inhibit glutamate-induced oxidative and ER stress-associated apoptosis in hippocampal HT22 cells

Glutamate toxicity increases the formation of reactive oxygen species (ROS) and intracellular calcium levels, resulting in neuronal dysfunction, neurodegenerative disorders, and death. Cordycepin is a derivative of the nucleoside adenosine, and is believed to exert neuroprotective effects against glutamate-induced oxidative toxicity in HT22 neuronal cells. Excessive glutamate induces oxidative and endoplasmic reticulum (ER) stress, gradually increasing ER-related pro-apoptotic transcription factor C/EBP homologous protein (CHOP) expression, and eventually up-regulating expression of the pro-apoptotic factor Bax. Cordycepin inhibits CHOP and Bax expressions, as well as p-ERK, p-JNK, and p-p38, all of which are involved in oxidative or ER stress-induced apoptosis. In addition, the increased production of ROS from excessive glutamate leads to elevation of mitochondrial membrane potential (MMP), a hallmark of mitochondrial dysfunction. Cordycepin retains MMP and reduces the elevated levels of ROS and Ca(2+) induced by glutamate. Caspases are crucial mediators involved in mitochondrial apoptosis, and while glutamate disrupts mitochondrial function, it does not change expression levels of caspase 3 and caspase 9. Similarly, cordycepin has no effect on caspase 3 and caspase 9 expressions; however, it decreases the expression of ER stress-specific caspase 12, which plays a key role in the initiation of ER stress-induced apoptosis. Finally, we found that the anti-apoptotic effects of cordycepin are partially dependent on activation of the adenosine A1 receptor, whereas an antagonist selectively attenuated the neuroprotective effects of cordycepin. Collectively, these results suggest that cordycepin could be a potential future therapeutic agent for neuronal disorders.

Influence of glycerol on production and structural-physical properties of cellulose from Acetobacter sp. V6 cultured in shake flasks.

Cost-effective production of bacterial cellulose (BC) by Acetobacter sp. V6 was investigated in shake culture using glycerol as carbon source and its structural and physical properties were determined. In medium containing 3% (w/v) glycerol, BC production was 4.98+/-0.03g/l after 7 days. This value was 3.8-fold higher than the yield in the glucose medium. FT-IR spectra revealed that all the BC samples were highly crystalline and were cellulose type capital I, Ukrainian. The crystallinity index value of the BC produced was 9% higher in the glycerol medium than in the glucose medium. Scanning electron micrographs showed that BC from the glycerol medium was more compact than that from the glucose medium. Water-holding capacity and viscosity of BC from the glycerol medium had 61.3% and 22.4% lower values than those from the glucose medium. These results suggest that glycerol could be a potential low-cost substrate for BC production by Acetobacter sp. V6, leading to the reduction in the production cost.

Growth-associated production of poly-β-hydroxybutyrate from glucose or alcoholic distillery wastewater by Actinobacillus sp. EL-9

SummaryThe characteristics of poly-β-hydroxybutyrate (PHB) production from glucose or alcoholic distillery wastewater by isolated Actinobacillus sp. EL-9 were investigated. PHB production was not dependent on nutrients limitation in Actinobacillus sp. EL-9. The PHB accumulation of Actibobacillus sp. EL-9 followed a growth-associated type where the cell growth and PHB accumulation were carried out simultaneously. The Actinobacillus sp. EL-9 was shown to synthesize and accumulate PHB from alcoholic distillery wastewater during growth. The best growth and PHB production were obtained with enzyme-hydrolyzed alcoholic distillery wastewater.

Halofuginone induces the apoptosis of breast cancer cells and inhibits migration via downregulation of matrix metalloproteinase-9

Halofuginone (HF) is extracted from Dichroa febrifuga, a plant used in traditional medicine. We report that the HF extract inhibits the growth of breast cancer cells and induces the generation of reactive oxygen species (ROS) and apoptosis, an important feature of potential anticancer agents. In addition, HF significantly reduces the migration and invasion of MCF-7 and MDA-MB-231 human breast cancer cells after 12-O-tetraecanoylphorbol-13-acetate (TPA) stimulation. As matrix metalloproteinase-9 plays a critical role in tumor metastasis, we analyzed its expression with the HF extract treatment. Western blot analysis and gelatin zymography showed that HF suppresses MMP-9 expression and activity concentration-dependently. HF also decreases the nuclear protein levels of nuclear factor kappa B (NF-κB) and c-fos (AP-1), critical transcription factors regulating MMP-9 expression through binding the MMP-9 promoter region. Luciferase assays showed that HF decreases TPA-induced MMP-9 promoter binding activities of NF-κB and AP-1. Taken together, these are the first results indicating that halofuginone may represent a promising new agent for breast cancer chemotherapy.

Anti-neuroinflammatory Effect of Emodin in LPS-Stimulated Microglia: Involvement of AMPK/Nrf2 Activation

AMPK/Nrf2 signaling regulates multiple antioxidative factors and exerts neuroprotective effects. Emodin is one of the main bioactive components extracted from Polygonum multiflorum, a plant possessing important activities for human health and for treating a variety of diseases. This study examined whether emodin can activate AMPK/Nrf2 signaling and induce the expression of genes targeted by this pathway. In addition, the anti-neuroinflammatory properties of emodin in lipopolysaccharide (LPS)-stimulated microglia were examined. In microglia, the emodin treatment increased the levels of LKB1, CaMKII, and AMPK phosphorylation. Emodin increased the translocation and transactivity of Nrf2 and enhanced the levels of HO-1 and NQO1. In addition, the emodin-mediated expression of HO-1 and NQO1 was attenuated completely by an AMPK inhibitor (compound C). Moreover, emodin decreased dramatically the LPS-induced production of NO and PGE2 as well as the protein expression and promoter activity of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In addition, emodin effectively inhibited the production of pro-inflammatory cytokines, TNF-α and IL-6, and reduced the level of IκBα phosphorylation, leading to the suppression of the nuclear translocation, phosphorylation, and transactivity of NF-κB. Emodin also suppressed the LPS-stimulated activation of STATs, JNK, and p38 MAPK. The anti-inflammatory effects of emodin were reversed by transfection with Nrf-2 and HO-1 siRNA and by a co-treatment with an AMPK inhibitor. These results suggest that emodin isolated from P. multiflorum can be used as a natural anti-neuroinflammatory agent that exerts its effects by inducing HO-1 and NQO1 via AMPK/Nrf2 signaling in microglia.

Sanguinarine inhibits invasiveness and the MMP-9 and COX-2 expression in TPA-induced breast cancer cells by inducing HO-1 expression.

Most complications of breast cancer are attributed to metastasis to distant organs, including lymph nodes, bone, lung and liver. Metastasis is considered the leading cause of mortality in patients with breast cancer. The emergence of anti-metastatic properties in breast cancer is an important clinical phenomenon affecting long-term survival. In the present study, we investigated the anti-invasive mechanism of sanguinarine by focusing on its role in inducing HO-1 in breast cancer cells. The results showed that sanguinarine inhibited TPA-induced MMP-9 and COX-2 mRNA and protein expression in a dose-dependent manner at non-cytotoxic concentrations. Similarly, the MMP-9 enzymatic activity and the PGE2 levels significantly decreased in MCF-7 breast cancer cells. TIMP-1 and TIMP-2, specific endogenous inhibitors of MMP-9, were slightly induced by sanguinarine. Subsequent studies revealed that sanguinarine suppressed TPA-induced NF-κB and AP-1 activation, as well as the phosphorylation of Akt and ERK. Furthermore, sanguinarine significantly inhibited TPA-induced invasion and migration in breast cancer cells. We also demonstrated that sanguinarine induced HO-1 expression, and that the inhibition of MMP-9 and COX-2 expression and the enzymatic activity of sanguinarine were abrogated by siRNA-mediated knockdown of HO-1 expression. Thus, knockdown of endogenous HO-1 decreased TPA-induced cell invasion. Overall, the results of the present study demonstrate that HO-1 plays a pivotal role in the anti-invasive response of sanguinarine in TPA-stimulated breast cancer cells.

Acanthopanax senticosus has a heme oxygenase-1 signaling-dependent effect on Porphyromonas gingivalis lipopolysaccharide-stimulated macrophages.

ETHNOPHARMACOLOGICAL RELEVANCE Acanthopanax senticosus (Rupr. & Maxim.) Harms (AS) has been used as a traditional medicine for the treatment of hypertension, rheumatism, ischemic heart disease, diabetes, and hepatitis in East Asia. This herb has been reported to possess anti-cancer, anti-diabetes, and anti-inflammatory properties. AIM OF THE STUDY To examine the anti-inflammatory activity of AS extract (ASE) and its mechanism of action in Porphyromonas gingivalis lipopolysaccharide (P. gingivalis LPS)-stimulated macrophages. MATERIALS AND METHODS P. gingivalis LPS was used to induce an inflammatory response in the murine macrophage cell line RAW 264.7. Pro-inflammatory cytokines were measured by using an enzyme-linked immunosorbent assay. We used western blot assays and real-time quantitative polymerase chain reaction to detect protein and mRNA expression, respectively. Luciferase assays were performed to determine the transactivity of transcription factors. Nuclear translocation of nuclear factor (NF)-κB was assessed by confocal microscopy. RESULTS ASE significantly induced the expression and activity of heme oxygenase-1 (HO-1), which is known to produce an anti-inflammatory effect, in RAW 264.7 cells, through NF-E2-related factor 2 (Nrf-2), Janus kinase, and extracellular signal-regulated kinase activation. ASE also effectively suppressed the production of pro-inflammatory cytokines, tumor necrosis factor α, interleukin (IL)-1β, and IL-6, and decreased the nuclear translocation and transactivity of activator protein-1 (AP-1) and NF-κB by inhibiting the phosphorylation of IκB-α in P. gingivalis LPS-stimulated macrophage cells. Furthermore, ASE inhibits signal transducer and activator of transcription (STAT)1 phosphorylation while it activates STAT3 phosphorylation in P. gingivalis LPS-stimulated RAW 264.7 cells. CONCLUSIONS Our study suggests that ASE produces anti-inflammatory effects on P. gingivalis LPS-stimulated macrophages through a reduction in AP-1 and NF-κB activity, modulation of STAT1 and STAT3 phosphorylation, and upregulation of HO-1 expression through the activation of mitogen-activated protein kinase and Nrf-2 signaling pathways. Therefore, ASE could be a candidate for the prevention and treatment of periodontal diseases that involve excessive inflammation.

Inhibitory Effects of Ginkgo biloba Extract on Inflammatory Mediator Production by Porphyromonas gingivalis Lipopolysaccharide in Murine Macrophages via Nrf-2 Mediated Heme Oxygenase-1 Signaling Pathways

Periodontitis is an oral chronic inflammatory disease that influences systemic diseases. Heme oxygenase-1 has several beneficial abilities through Nrf-2 regulation. Ginkgo biloba has been reported to have anti-inflammatory effects associated with heme oxygenase-1 (HO-1) expression. In this study, we investigated whether the anti-inflammatory effects of G. biloba were involved with Nrf-2-mediated HO-1 expression in Porphyromonas gingivalis LPS-stimulated RAW264.7 macrophage cells. G. biloba was extracted with ethyl acetate (EGB). EGB exhibited anti-inflammatory activities, which suppressed the production of pro-inflammatory mediators, the activation of mitogen-activated protein kinases, and nuclear translocation of transcription factors. EGB also up-regulated the HO-1 expression, and the Nrf-2 level in the nucleus and its transactivity. Furthermore, reduced pro-inflammatory mediator levels by EGB were inverted in the presence of SnPP. The collective results suggest that the anti-inflammatory effects of EGB are due to the HO-1 expression via up-regulation of Nrf-2 in RAW 264.7 cells stimulated by P. gingivalis LPS.

Acanthopanax senticosus exerts neuroprotective effects through HO-1 signaling in hippocampal and microglial cells.

Extracts of Acanthopanax senticosus, a traditional herb commonly found in Northeastern Asia, are used for treating neurodegenerative disorders such as ischemia and depression. However, the mechanisms of its neuroinflammatory and cytoprotective effects have not been investigated. We examined the mechanism of A. senticosus activity in anti-neuroinflammatory and neuroprotective processes. HO-1 is an inducible enzyme present in most cell lines. ASE increased HO-1 expression, which reduced LPS-induced nitric oxide/ROS production in BV2 cells. Moreover, the induction of HO-1 expression protected cells against glutamate-induced neuronal cell death. Activation of the p38-CREB pathway and translocation of Nrf2 are strongly involved in ASE-induced HO-1 expression. Our results showed that ASE-induced HO-1 expression through the p38-CREB pathway plays an important role in the generation of anti-neuroinflammatory and neuroprotective responses. ASE also increases the translocation of Nrf2 to regulate HO-1 expression. Furthermore, our results indicate that ASE serves as a potential therapeutic agent for neuronal disorders.

Suppression of α-MSH and IBMX-induced melanogenesis by cordycepin via inhibition of CREB and MITF, and activation of PI3K/Akt and ERK-dependent mechanisms

Cordycepin has been a traditional medicine in China and Korea for centuries. This study explored the inhibitory effect of cordycepin on melanogenesis and the relative molecular mechanisms. Cordycepin inhibited melanin synthesis-related enzymes, such as tyrosinase, tyrosinase-related protein-1 (TRP1) and tyrosinase-related protein-2 (TRP2). α-MSH and IBMX were reported as melanin synthesis enhancers. Both of them could increase intracellular melanin synthesis by activation of the microphthalmia-associated transcription factor (MITF) signaling pathway. In the MITF pathway, the phosphorylation of cAMP related binding protein (CREB) activated the transcription of MITF, resulting in increasing melanin synthesis. Cordycepin also decreased the phosphorylation of CREB induced by α-MSH and IBMX in B16F10 melanoma cells. Accordingly, cordycepin inhibited melanogenesis signaling pathways by activating ERK and AKT signaling pathways to regulate the suppression of MITF and its downstream pathways including tyrosinase, TRP1 and TRP2. These results indicate the role of cordycepin as a potent depigmenting agent for cosmetics.