• Biomolecules & Therapeutics
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• v.28 no.2
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• pp.163-171
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• 2020

Silibinin exhibits antidiabetic potential by preserving the mass and function of pancreatic β-cells through up-regulation of estrogen receptor-α (ERα) expression. However, the underlying protective mechanism of silibinin in pancreatic β-cells is still unclear. In the current study, we sought to determine whether ERα acts as the target of silibinin for the modulation of antioxidative response in pancreatic β-cells under high glucose and high fat conditions. Our in vivo study revealed that a 4-week oral administration of silibinin (100 mg/kg/day) decreased fasting blood glucose with a concurrent increase in levels of serum insulin in high-fat diet/streptozotocin-induced type 2 diabetic rats. Moreover, expression of ERα, NF-E2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in pancreatic β-cells in pancreatic islets was increased by silibinin treatment. Accordingly, silibinin (10 μM) elevated viability, insulin biosynthesis, and insulin secretion of high glucose/palmitate-treated INS-1 cells accompanied by increased expression of ERα, Nrf2, and HO-1 as well as decreased reactive oxygen species production in vitro. Treatment using an ERα antagonist (MPP) in INS-1 cells or silencing ERα expression in INS-1 and NIT-1 cells with siRNA abolished the protective effects of silibinin. Our study suggests that silibinin activates the Nrf2-antioxidative pathways in pancreatic β-cells through regulation of ERα expression.

• Parasites, Hosts and Diseases
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• v.52 no.5
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• pp.459-469
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• 2014

Entamoeba histolytica is a tissue-invasive protozoan parasite causing dysentery in humans. During infection of colonic tissues, amoebic trophozoites are able to kill host cells via apoptosis or necrosis, both of which trigger IL-8-mediated acute inflammatory responses. However, the signaling pathways involved in host cell death induced by E. histolytica have not yet been fully defined. In this study, we examined whether calpain plays a role in the cleavage of pro-survival transcription factors during cell death of colonic epithelial cells, induced by live E. histolytica trophozoites. Incubation with amoebic trophozoites induced activation of m-calpain in a time- and dose-dependent manner. Moreover, incubation with amoebae resulted in marked degradation of STAT proteins (STAT3 and STAT5) and NF-${\kappa}B$ (p65) in Caco-2 cells. However, $I{\kappa}B$, an inhibitor of NF-${\kappa}B$, was not cleaved in Caco-2 cells following adherence of E. histolytica. Entamoeba-induced cleavage of STAT proteins and NF-${\kappa}B$ was partially inhibited by pretreatment of cells with a cell-permeable calpain inhibitor, calpeptin. In contrast, E. histolytica did not induce cleavage of caspase-3 in Caco-2 cells. Furthermore, pretreatment of Caco-2 cells with a calpain inhibitor, calpeptin (but not the pan-caspase inhibitor, z-VAD-fmk) or m-calpain siRNA partially reduced Entamoeba-induced DNA fragmentation in Caco-2 cells. These results suggest that calpain plays an important role in E. histolytica-induced degradation of NF-${\kappa}B$ and STATs in colonic epithelial cells, which ultimately accelerates cell death.

• Journal of Ginseng Research
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• v.35 no.3
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• pp.352-359
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• 2011

Korean red ginseng (KRG) is used worldwide as a popular traditional herbal medicine. KRG has shown beneficial effects on cardiovascular diseases, such as atherosclerosis, diabetes, and hypertension. Up-regulation of a cytoprotective protein, heme oxygenase (HO)-1, is considered to augment the cellular defense against various agents that may induce cytotoxic injury. In the present study, we demonstrate that KRG water extract induces HO-1 expression in human umbilical vein endothelial cells (HUVECs) and possible involvement of the anti-oxidant transcription factor nuclear factor-eythroid 2-related factor 2 (Nrf2). KRG-induced HO-1 expression was examined by western blots, reverse transcriptase polymerase chain reaction and immunofluorescence staining. Specific silencing of Nrf2 genes with Nrf2-siRNA in HUVECs abolished HO-1 expression. In addition, the HO inhibitor zinc protoporphyrin blunted the preventive effect of KRG on $H_2O_2$-induced cell death, as demonstrated by terminal transferase dUTP nick end labeling assay. Taken together, these results suggest that KRG may exert a vasculoprotective effect through Nrf2-mediated HO-1 induction in human endothelial cell by inhibition of cell death.

• Nutrition Research and Practice
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• v.4 no.4
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• pp.276-282
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• 2010

The principal objective of this study was to evaluate the chemopreventive and therapeutic effects of a combination of all-trans-retinoic acid (RA) and knockdown of delta-like 1 homologue (Drosophila) (DLK1) on neuroblastoma, the most common malignant disease in children. As unfavorable neuroblastoma is poorly differentiated, neuroblastoma cell was induced differentiation by RA or DLK1 knockdown. Neuroblastoma cells showed elongated neurite growth, a hallmark of neuronal differentiation at various doses of RA, as well as by DLK1 knockdown. In order to determine whether or not a combination of RA and DLK1 knockdown exerts a greater chemotherapeutic effect on neuroblastoma, cells were incubated at 10 nM RA after being transfected with SiRNA-DLK1. Neuronal differentiation was increased more by a combination of RA and DLK1 knockdown than by single treatment. Additionally, in order to assess the signal pathway of neuroblastoma differentiation induced by RA and DLK1 knockdown, treatment with the specific MEK/ERK inhibitors, U0126 and PD 98059, was applied to differentiated neuroblastoma cells. Differentiation induced by RA and DLK1 knockdown increased ERK phosphorylation. The MEK/ERK inhibitor U0126 completely inhibited neuronal differentiation induced by both RA and DLK1 knockdown, whereas PD98059 partially blocked neuronal differentiation. After the withdrawal of inhibitors, cellular differentiation was fully recovered. This study is, to the best of our knowledge, the first to demonstrate that the specific inhibitors of the MEK/ERK pathway, U0126 and PD98059, exert differential effects on the ERK phosphorylation induced by RA or DLK1 knockdown. Based on the observations of this study, it can be concluded that a combination of RA and DLK1 knockdown increases neuronal differentiation for the control of the malignant growth of human neuroblastomas, and also that both MEK1 and MEK2 are required for the differentiation induced by RA and DLK1 knockdown.

• BMB Reports
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• v.45 no.11
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• pp.659-664
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• 2012

Extracellular superoxide dismutase (EC-SOD) overexpression modulates cellular responses such as tumor cell suppression and is induced by $IFN{\gamma}$. Therefore, we examined the role of EC-SOD in $IFN{\gamma}$-mediated tumor cell suppression. We observed that the dominant-negative protein kinase C delta ($PKC{\delta}$) suppresses $IFN{\gamma}$-induced EC-SOD expression in both keratinocytes and melanoma cells. Our results also showed that $PKC{\delta}$-induced EC-SOD expression was reduced by pretreatment with a PKC-specific inhibitor or a siRNA against $PKC{\delta}$. $PKC{\delta}$-induced EC-SOD expression suppressed cell proliferations by the up-regulation of p21 and Rb, and the downregulation of cyclin A and D. Finally, we demonstrated that increased expression of EC-SOD drastically suppressed lung melanoma proliferation in an EC-SOD transgenic mouse via p21 expression. In summary, our findings suggest that $IFN{\gamma}$-induced EC-SOD expression occurs via activation of $PKC{\delta}$. Therefore, the upregulation of EC-SOD may be effective for prevention of various cancers, including melanoma, via cell cycle arrest.

• BMB Reports
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• v.45 no.11
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• pp.647-652
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• 2012

We previously reported that MSTO-211H cells have a higher capacity to regulate Nrf2 activation in response to changes in the cellular redox environment. To further characterize its biological significance, the response of Nrf2, a transcription factor that regulates ARE-containing genes, on the synergistic cytotoxic effect of clofarabine and resveratrol was investigated in mesothelioma cells. The combination treatment showed a marked growth-inhibitory effect, which was accompanied by suppression of Nrf2 activation and decreased expression of heme oxygenase-1 (HO-1). While transient overexpression of Nrf2 conferred protection against the cytotoxicity caused by their combination, knockdown of Nrf2 expression using siRNA enhanced their cytotoxic effect. Pretreatment with Ly294002, a PI3K inhibitor, augmented the decrease in HO-1 level by their combination, whereas no obvious changes were observed in Nrf2 levels. Altogether, these results suggest that the synergistic cytotoxic effect of clofarabine and resveratrol was mediated, at least in part, through suppression of Nrf2 signaling.

• Parasites, Hosts and Diseases
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• v.56 no.2
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• pp.121-127
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• 2018

To survey the prevalence of Sarcocystis infections, 210 heart samples were collected from Korean native cattle (Bos taurus coreanae) at an abattoir in Daejeon Metropolitan City, Republic of Korea. Sarcocysts were detected form 31 specimens (14.8%) and identified as Sarcocystis cruzi via transmission electron microscopy. The wall of S. cruzi has flattened protrusions that did not contain fibrils or microfilaments. The protrusions arose irregularly from the base, contained a fine granular substance, lacked internal microfilaments, and measured approximately $0.21-1.25{\mu}m$ in length and $0.05-0.07{\mu}m$ in width. Sequence analysis revealed 99.5% homology to S. cruzi. This is the first report on the prevalence of S. cruzi in native cattle from the Republic of Korea.

• Journal of Microbiology and Biotechnology
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• v.30 no.2
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• pp.196-205
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• 2020

In this study, the acidic lipase from Aspergillus niger (ANL) was homologously expressed in A. niger. The expression of ANL was significantly improved by the expression of the native ANL with the introns, the addition of the Kozak sequence and the optimization of the signal sequences. When the cDNA sequence of ANL fused with the glaA signal was expressed under the gpdA promoter in A. niger, no lipase activity could be detected. We then tried to improve the expression by using the full-length ANL gene containing three introns, and the lipase activity in the supernatant reached 75.80 U/ml, probably as a result of a more stable mRNA structure. The expression was further improved to 100.60 U/ml by introducing a Kozak sequence around the start codon due to a higher translation efficiency. Finally, the effects of three signal sequences including the cbhI signal, the ANL signal and the glaA signal on the lipase expression were evaluated. The transformant with the cbhI signal showed the highest lipase activity (314.67 U/ml), which was 1.90-fold and 3.13-fold higher than those with the ANL signal and the glaA signal, respectively. The acidic lipase was characterized and its highest activity was detected at pH 3.0 and a temperature of 45℃. These results provided promising strategies for the production of the acidic lipase from A. niger.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.22
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• pp.10015-10020
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• 2014

Background: Fentanyl is used as an analgesic to treat pain in a variety of patients with cancer and recently it has become considered to also act as an antitumor agent. The study present was designed to investigate the effects of fentanyl on colorectal cancer cell growth and plausible mechanisms. Materials and Methods: The human colorectal carcinoma cell line HCT116 was subcutaneously injected into nude mice. The viability of HCT116 was tested by MTT assay, and apoptosis by flow cytometry and caspase-3 activity. The expression of Sirt1 and NF-${\kappa}B$ were evaluated by Western blotting and the levels of Sirt1 and NF-${\kappa}B$ by fluorescence method. SiRNA was used to silence and Ad-Sirt1 to overexpress Sirt1. Results: Our data showed that fentanyl could inhibit tumor growth, with increased expression of Sirt1 and down-regulation of Ac-p65 in tumors. Compared with control cells without treatment, HCT116 cells that were incubated with fentanyl had a higher apoptotic rate. Moreover, fentanyl could increase expression and activity of Sirt1 and inhibitor expression and activity of NF-${\kappa}B$, which might be mechanisms of fentanyl action. Conclusions: Fentanyl increased colorectal carcinoma cell apoptosis by inhibition of NF-${\kappa}B$ activation in a Sirt1-dependent manner.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7137-7141
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• 2013

Several studies have shown that nemo-like kinase (NLK) plays a vital role in apoptosis of cancer cells. The present research concerned effects and mechanisms of Taxol on NLK knockdown human laryngeal cancerHep-2 cell lines in vitro. Using RNAi, methyl-thiazoltetrazolium (MTT) assays, real-time RT-PCR, Western blotting and flow cytometry analysis, growth and the cell cycle progression of NLK knockdown Hep-2 cells and expression of downstream molecules were observed. Cell growth was obviously suppressed in the Taxol treated group (P<0.001, 48 hours). Cell numbers of combined Taxol-based chemotherapy with lentivirus mediated RNAi treatment group (Lv-shNLK+Taxol goup) were significantly different from NLK-specific siRNA lentivirus infected group (Lv-shNLK group) (p<0.001). Flow cytometry analysis revealed that Lv-shNLK+Taxol caused the G0/G1-phase DNA content to decrease from 44.1 to 3.33% (p<0.001) and the S-phase DNA content to increase from 38.4 to 82.0% (p<0.001), in comparison with the Lv-shNLK+Taxol group. Immunoblot analysis showed that knockdown of NLK led to significant reduction in the levels of cyclin D1, PCNA and PARP, whereas cyclin B1 was elevated in. Cell growth was also obviously suppressed in the Hep-2 cell line, knockdown of NLK making them more sensitive to Taxol treatment. NLK is expected to become a target of new laryngeal cancer gene therapies.