Hwan-Suck Chung

Expression of proinflammatory cytokines via HIF-1α and NF-κB activation on desferrioxamine-stimulated HMC-1 cells

Abstract We investigated the expression and the role of hypoxia-inducible factor 1α (HIF-1α) on the desferrioxamine (DFX)-induced cytokine production in human mast cells, HMC-1 cells. HIF-1α mRNA was constitutively expressed in mast cell lines including the P815, RBL-2H3, and HMC-1. DFX (100xa0μM) resulted in a great increase in protein levels of HIF-1α in HMC-1 cells, but it did not affect HIF-1α mRNA expression. Iron (HIF-1 inhibitor) inhibited increase of HIF-1α and NF-κB protein levels. Pyrriolidine-dithiocarbamate (PDTC, NF-κB inhibitor) inhibited increase of NF-κB protein levels, but it slightly increased HIF-1α protein levels. In addition, DFX significantly increased the production of IL-6, IL-8, and TNF-α in HMC-1 ( P P

Antiproliferative effects of alkaloids from Sedum sarmentosum on murine and human hepatoma cell lines.

The whole plant of Sedum sarmentosum (SS) has been traditionally used for the treatment of chronic viral hepatitis in China and South Korea. Certain hepatitis virus causes acute and chronic hepatitis and induces hepatocellular carcinoma (HC). In the present study, we examined whether the crude alkaloid fraction (CAF) of SS had any anticancer effects on hepatoma cell lines. Murine hepatoma (BNL CL. 2) and human hepatoma (HepG2) cell lines were cultured in the presence of CAF of SS at various doses (50-150 microg/ml) for 24 or 48 h. CAF caused a dose-dependent inhibition of cell proliferation without necrosis or apoptosis. Antiproliferative effects of CAF of SS were associated with an increase in the number of cells in the G1 phase of cell cycle. This study suggests that SS may improve survival of hepatoma patients via the inhibition of excessive growth of tumor cells.

The aqueous extract of Rhodiola sachalinensis root enhances the expression of inducible nitric oxide synthase gene in RAW264.7 macrophages

In the present study, we examined the effects of the aqueous extract of Rhodiola sachalinensis root (RSE) on the expression of inducible nitric oxide (NO) synthase (iNOS) gene in RAW264.7 macrophages. RSE synergistically increased NO synthesis in interferon-gamma-primed macrophages. Reverse transcriptase polymerase chain reaction and Northern blotting analysis revealed that RSE may provide a second triggering signal for the synergistic induction of iNOS mRNA expression. Thus, iNOS-mediated NO synthesis in response to RSE may be one mechanism whereby this herbal medicine elicits its therapeutic effects.

Induction of apoptosis by 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol from Isaria japonica Yasuda through intracellular reactive oxygen species formation and caspase-3 activation in human leukemia HL-60 cells

Recently we have reported that the trichothecene mycotoxin 4-acetyl-12,13-epoxyl-9-trichothecene-3,15-diol (AETD) from the fruiting bodies of Isaria japonica Yasuda is a potent inducer of apoptosis in human promyelocytic HL-60 cells. The present study aims to characterize the molecular events leading to AETD-induced apoptosis in HL-60 cells. The percentage of apoptotic cells (annexin-V-positive cell population) increased dose- and time-dependently after AETD exposure. Apoptosis of HL-60 cells by AETD was associated with the formation of intracellular reactive oxygen species (ROS), the depletion of intracellular glutathione (GSH) and the activation of caspase-3. Pretreating the cells with the antioxidant N-acetyl-L-cystein (NAC) and the caspase-3 inhibitor Z-DEVD-fmk abrogated AETD-induced apoptosis and caspase-3 activation. NAC blocked intracellular ROS formation and GSH depletion, but Z-DEVD-fmk did not. These results indicate that AETD induces apoptosis in HL-60 cells by causing intracellular ROS formation and GSH depletion followed by the downstream event of caspase-3 activation.

Dehydrocostus lactone enhances tumor necrosis factor-α-induced apoptosis of human leukemia HL-60 cells

Sesquiterpene lactones have raised considerable interest because of their ability to block the activation of nuclear transcription factor‐κB (NF‐κB). NF‐κB plays an important role in the resistance of cancer cells to the induction of apoptosis by anticancer drugs and tumor necrosis factor‐α (TNF‐α). Pharmacological inhibition of NF‐κB offers the promise of enhancing the efficacy of anticancer therapies. Here, we demonstrate that dehydrocostus lactone (DL), the major sesquiterpene lactone isolated from the roots of Saussurea lappa, inhibits NF‐κB activation by preventing TNF‐α‐induced degradation and phosphorylation of its inhibitory protein I‐κBα in human leukemia HL‐60 cells and that DL renders HL‐60 cells susceptible to TNF‐α‐induced apoptosis by enhancing caspase‐8 and caspase‐3 activities.

Salidroside from Rhodiola sachalinensis Protects Neuronal PC12 Cells Against Cytotoxicity Induced by Amyloid‐β

Abstract The amyloid β‐peptide (Aβ)‐induced oxidative stress is a well‐established pathway of neuronal cell death in Alzheimers disease (AD). Salidroside, one of the major compounds from the roots of Rhodiola species (Crassulaceae), was investigated in vitro for its cytoprotection against Aβ‐induced toxicity on rat neuronal PC12 cells. Salidroside significantly reduced Aβ‐induced cytotoxicity in a dose‐dependent manner. Salidroside also reduced Aβ‐mediated intracellular accumulation of reactive oxygen species and malondialdehyde (MDA), a product of lipid peroxides, by preventing Aβ‐induced decline of antioxidant enzyme activities. These results suggest that salidroside protects neuronal PC12 cells from Aβ‐induced cytotoxicity via its antioxidant pathway.

Inhibitory effects of the stem bark of Catalpa ovata G. Don. (Bignoniaceae) on the productions of tumor necrosis factor-α and nitric oxide by the lipopolisaccharide-stimulated RAW 264.7 macrophages

In order to validate the use of the stem bark of Catalpa ovata G. Don. (Bignoniaceae) as an anti-inflammatory drug in the traditional Korean medicine, we have investigated the effects of the methanol extract of this folk medicine on the productions of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) on RAW 264.7 macrophages activated with the endotoxin lipopolysaccharide. The extract inhibited the productions of TNF-alpha and NO with significant decreases in mRNA levels of TNF-alpha and inducible NO synthase, suggesting that the stem bark of Catalpa ovata may have therapeutic potential in the control of inflammatory disorders.

p38 MAPK and NF-κB on IL-6 Release in Human Gingival Fibroblasts

The induction of interleukin-6 (IL-6) using a proinflammatory cytokine (IL-1β) was studied in human gingival fibroblasts (HGFs) in relation to p38 MAPK and NF-κB transcription factor. When added to HGFs, IL-1β had a stimulatory effect on the production of IL-6, and this effect was significantly reduced by SB203580, a specific p38 MAPK inhibitor. In addition, the stimulation of IL-6 release also was reduced by the addition of pyrrolidine dithiocarbamate or NF-κB SN50, which has been reported as potent NF-κB inhibitor. Both the NF-κB inhibitors in the presence of SB203580 had more inhibitory effect on IL-6 release. IL-1β stimulated NF-κB binding affinity as well as p38 MAP kinase activation, leading to the release of IL-6. However, a specific inhibitor of p38 MAPK, SB203580, had no effect on the NF-κB activation, and both the NF-κB inhibitors failed to reduce the p38 MAPK activation in the IL-1β-stimulated HGFs. These results strongly suggest that both p38 MAPK and NF-κB are required in IL-1β-induced IL-6 synthesis and that these two IL-1β-activated pathways can be primarily dissociated.

Nitric oxide and tumor necrosis factor-α production by Ixeris dentata in mouse peritoneal macrophages

Abstract Using mouse peritoneal macrophages, we have examined the mechanism by which Ixeris dentata (IXD) regulates nitric oxide (NO) production. When IXD was used in combination with recombinant interferon-γ (rIFN-γ), there was a marked cooperative induction of NO production. However, IXD had no effect on NO production by itself. The increased production of NO from rIFN-γ plus IXD-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-κB). Furthermore, treatment with IXD alone or rIFN-γ plus IXD in peritoneal macrophages caused a significant increase in tumor necrosis factor-α (TNF-α) production. PDTC decreased TNF-α production induced by IXD significantly. These findings demonstrate that IXD increases the production of NO and TNF-α by rIFN-γ-primed macrophages and suggest that NF-κB plays a critical role in mediating these effects of IXD.

Activation of inducible nitric oxide synthase by Euonymus alatus in mouse peritoneal macrophages

BACKGROUNDnEuonymus alatus (EA) has been used for tumor therapy. However, it is still unclear how this herb prevents the diseases in experimental models. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of tumors has received increasing attention.nnnMETHODSnUsing mouse peritoneal macrophages, we have examined the mechanism by which EA regulates NO production.nnnRESULTSnWhen EA was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. However, EA had no effect on NO production by itself. The increased production of NO from rIFN-gamma plus EA-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappaB). Furthermore, treatment of peritoneal macrophages with rIFN-gamma plus EA caused a significant increase in tumor necrosis factor-alpha (TNF-alpha) production. PDTC also decreased the effects of EA on TNF-alpha production significantly.nnnCONCLUSIONSnEA increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of EA.