• Journal of Korean Neurosurgical Society
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• 제59권3호
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• pp.259-268
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• 2016

Objective : Accumulation of advanced glycation end-products (AGE) and mitochondrial glycation is importantly implicated in the pathological changes of the brain associated with diabetic complications, Alzheimer disease, and aging. The present study was undertaken to determine whether sildenafil, a type 5 phosphodiesterase type (PDE-5) inhibitor, has beneficial effect on neuronal cells challenged with AGE-induced oxidative stress to preserve their mitochondrial functional integrity. Methods : HT-22 hippocampal neuronal cells were exposed to AGE and changes in the mitochondrial functional parameters were determined. Pretreatment of cells with sildenafil effectively ameliorated these AGE-induced deterioration of mitochondrial functional integrity. Results : AGE-treated cells lost their mitochondrial functional integrity which was estimated by their MTT reduction ability and intracellular ATP concentration. These cells exhibited stimulated generation of reactive oxygen species (ROS), disruption of mitochondrial membrane potential, induction of mitochondrial permeability transition, and release of the cytochrome C, activation of the caspase-3 accompanied by apoptosis. Western blot analyses and qRT-PCR demonstrated that sildenafil increased the expression level of the heme oxygenase-1 (HO-1). CoPP and bilirubin, an inducer of HO-1 and a metabolic product of HO-1, respectively, provided a similar protective effects. On the contrary, the HO-1 inhibitor ZnPP IX blocked the effect of sildenafil. Transfection with HO-1 siRNA significantly reduced the protective effect of sildenafil on the loss of MTT reduction ability and MPT induction in AGE-treated cells. Conclusion : Taken together, our results suggested that sildenafil provides beneficial effect to protect the HT-22 hippocampal neuronal cells against AGE-induced deterioration of mitochondrial integrity, and upregulation of HO-1 is involved in the underlying mechanism.

• BMB Reports
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• 제52권7호
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• pp.469-474
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• 2019

Kruppel-like factor 2 (KLF2) has been implicated in the regulation of cell proliferation, differentiation, and survival in a variety of cells. Recently, it has been reported that KLF2 regulates the p65-mediated transactivation of $NF-{\kappa}B$. Although the $NF-{\kappa}B$ pathway plays an important role in the differentiation of osteoclasts and osteoblasts, the role of KLF2 in these bone cells has not yet been fully elucidated. In this study, we demonstrated that KLF2 regulates osteoclast and osteoblast differentiation. The overexpression of KLF2 in osteoclast precursor cells inhibited osteoclast differentiation by downregulating c-Fos, NFATc1, and TRAP expression, while KLF2 overexpression in osteoblasts enhanced osteoblast differentiation and function by upregulating Runx2, ALP, and BSP expression. Conversely, the downregulation of KLF2 with KLF2-specific siRNA increased osteoclast differentiation and inhibited osteoblast differentiation. Moreover, the overexpression of interferon regulatory protein 2-binding protein 2 (IRF2BP2), a regulator of KLF2, suppressed osteoclast differentiation and enhanced osteoblast differentiation and function. These effects were reversed by downregulating KLF2. Collectively, our data provide new insights and evidence to suggest that the IRF2BP2/KLF2 axis mediates osteoclast and osteoblast differentiation, thereby affecting bone homeostasis.

• BMB Reports
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• 제49권1호
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• pp.57-62
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• 2016

Up-regulation of adhesion molecules plays an important role in the infiltration of leukocytes into the skin during the development of various inflammatory skin diseases, such as atopic dermatitis. In this study, we investigated the modulatory effects of 2,3-dimethoxy-2′-hydroxychalcone (DMHC) on tumor necrosis factor (TNF)-α-induced intercellular adhesion molecule-1 (ICAM-1) expression and monocyte adhesiveness, as well as the molecular mechanisms underlying its action in the HaCaT human keratinocyte cell line. Pre-treating HaCaT cells with DMHC significantly suppressed TNF-α-induced ICAM-1 expression and subsequent monocyte adhesiveness. DMHC inhibited TNF-α-induced activation of NF-ᴋB. In addition, DMHC induced HO-1 expression as well as NRF2 activation. Furthermore, HO-1 knockdown using siRNA reversed the inhibitory effect of DMHC on TNF-α-induced ICAM-1 expression and adhesion of monocytes to keratinocytes. These results suggest that DMHC may inhibit TNF-α-induced ICAM-1 expression and adhesion of monocytes to keratinocytes by suppressing the signaling cascades leading to NF-ᴋB activation and inducing HO-1 expression in keratinocytes. [BMB Reports 2016; 49(1): 57-62]

• Journal of Ginseng Research
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• 제37권3호
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• pp.315-323
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• 2013

Ginseng is known to have antistress effects. Previously, red ginseng (RG) was shown to repress stress-induced peptidyl arginine deiminase type IV (PADI4) via estrogen receptor ${\beta}$ ($ER{\beta}$) in the brain, thus inhibiting brain cell apoptosis. Moreover, tumor necrosis factor (TNF)-${\alpha}$ plays a critical role in immobilization (IMO) stress. However, the signaling pathway of RG-mediated repressesion of inflammation is not completely understood. In this study, we determined how RG modulated gene expression in stressed brain cells. Since secretion of TNF-${\alpha}$ is modulated via TNF-${\alpha}$ converting enzyme (TACE) and nuclear factor (NF)-${\kappa}B$, we examined the inflammatory pathway in stressed brain cells. Immunohistochemistry revealed that TACE was induced by IMO stress, but RG repressed TACE induction. Moreover, PADI4 siRNA repressed TACE expression compared to the mock transfected control suggesting that PADI4 was required for TACE expression. A reporter assay also revealed that $H_2O_2$ oxidative stress induced NF-${\kappa}B$ in neuroblastoma SK-N-SH cells, however, RG pretreatment repressed NF-${\kappa}B$ induction. These findings were supported by significant induction of nitric oxide and reactive oxygen species (ROS) by oxidative stress, which could be repressed by RG administration. Taken together, RG appeared to repress stress-induced PADI4 via TACE and NF-${\kappa}B$ in brain cells thus preventing production of ROS and subsequently protecting brain cells from apoptosis.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.6117-6121
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• 2015

Background: Most northeast Thai vegetables may play roles in human health by acting as antioxidant and anticancer agents. Recent study showed that Cratoxylum formosum subsp. pruniflorum (Kurz.) Gogel. (Teawdang) could inhibit growth of liver cancer cell lines. Cervical cancer, which has human papilloma virus as its main cause, is found at high incidence in Thailand. Due to increasing drug resistance, searches for potential anticancer compounds from natural source are required. Therefore, our purpose was to evaluate the cytotoxicity of Teawdang extracts in cervical cancer cell lines. Materials and Methods: Teawdang edible parts, purchased from Khon Kaen market during July-October 2013 was extracted with organic solvent. Phenolic profiles of crude hexane (CHE), ethyl acetate (CEE), methanol (CME) and water (CWE) extracts were performed by high performance liquid chromatographic (HPLC) techniques. Their cytotoxic effects on cervical cancer cells were investigated with HPV-non infected (C-33A) and HPV-infected (HeLa and SiHa) cell lines. Results: HPLC profiles showed that all crude extracts contained caffeine, ferulic acid and resveratrol. CME and CEE had high contents of gallic acid and quercetin. Catechin was found only in CWE. Cytotoxicity test showed that CEE had the lowest IC50 on HeLa ($143.18{\pm}13.35 {\mu}g/mL$) and SiHa cells ($106.45{\pm}15.73{\mu}g/mL$). C-33A cells were inhibited by CWE ($IC50=130.95{\pm}3.83{\mu}g/mL$). Conclusions: There were several phenolic compounds in Teawdang extracts which may have cytotoxic effects on cervical cancer cell lines. Investigation of these bioactive compounds as new sources of anticancer agents is recommended.

• Asian Pacific Journal of Cancer Prevention
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• 제16권16호
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• pp.7155-7159
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• 2015

Background: Oral cancer is a health problem in Thailand. Cratoxylum formosum subsp. pruniflorum Gogel (Teawdang), normally consumed in northeast Thailand, has proven cytotoxic to cervical cancer cell lines including HeLa, SiHa and C-33A. Recently, Asian oral cancer cell lines, ORL-48 and ORL-136, were established. Therefore, we aimed to study cytotoxicity of Teawdang in these. Total phenolic (TPC) and flavonoid content (TFC), and antioxidant activity of Teawdang were also determined. Materials and Methods: Teawdang was purchased from Khon Kaen market during June-October 2013. Hexane (CHE), ethyl acetate (CEE) and methanol (CME) extracts of its edible part were analyzed for TPC by the folin-ciocalteau method and for TFC by an aluminium colorimetric method. Antioxidant activity and cytotoxicity in normal Vero cells and oral cancer cells were investigated. Cell viability was assessed using 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Results: CME and CEE had higher TPC and TFC and antioxidant activity than CHE. Both CME and CEE, at $200{\mu}g$ dry wt/mL, were cytotoxic to the studied oral cancer cell lines. However, CME was cytotoxic to Vero cells whereas CEE was not. Compared to Vero cells, CEE significantly inhibited ORL-48 and ORL-136 growth (p=0.03 and p=0.02, respectively). Conclusions: CEE exhibited cytotoxic effects on the studied oral cancer cell lines but not normal Vero cells. The bioactive compounds in CEE should be further purified and elucidated for their mechanisms of action for development as anticancer agents.

• Biomolecules & Therapeutics
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• 제24권5호
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• pp.501-509
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• 2016

Shikonin, which derives from Lithospermum erythrorhizon, has been traditionally used against a variety of diseases, including cancer, in Eastern Asia. Here we determined that shikonin inhibits proliferation of gastric cancer cells by inducing apoptosis. Shikonin's biological activity was validated by observing cell viability, caspase 3 activity, reactive oxygen species (ROS) generation, and apoptotic marker expressions in AGS stomach cancer cells. The concentration range of shikonin was 35-250 nM with the incubation time of 6 h. Protein levels of Nrf2 and p53 were evaluated by western blotting and confirmed by real-time PCR. Our results revealed that shikonin induced the generation of ROS as well as caspase 3-dependent apoptosis. c-Jun-N-terminal kinases (JNK) activity was significantly elevated in shikonin-treated cells, thereby linking JNK to apoptosis. Furthermore, our results revealed that shikonin induced p53 expression but repressed Nrf2 expression. Moreover, our results suggested that there may be a co-regulation between p53 and Nrf2, in which transfection with siNrf2 induced the p53 expression. We demonstrated for the first time that shikonin activated cell apoptosis in AGS cells via caspase 3- and JNK-dependent pathways, as well as through the p53-Nrf2 mediated signal pathway. Our study validates in partly the contribution of shikonin as a new therapeutic approaches/agent for cancer chemotherapy.

• Molecules and Cells
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• 제21권1호
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• pp.121-128
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• 2006

Maitotoxin (MTX) is known as one of the most potent marine toxins involved in Ciguatera poisoning, but intracellular signaling pathways caused by MTX was not fully understood. Thus, we have investigated whether intracellular reactive oxygen species (ROS) are involved in MTX-induced cellular responses in human umbilical vein endothelial cells. MTX induced a dose-dependent increase of intracellular [$Ca^{2+}$]. MTX stimulated the production of intracellular ROS in a dose- and time-dependent manner, which was suppressed by BAPTA-AM, an intracellular $Ca^{2+}$ chelator. Ionomycin also elevated the ROS production in a dose-dependent manner. MTX elevated transamidation activity in a time-dependent manner and the activation was largely inhibited by transfection of tissue transglutaminase siRNA. The activation of tissue transglutaminase and ERK1/2 by MTX was suppressed by BAPTA-AM or ROS scavengers. In addition, MTX-induced cell death was significantly delayed by BAPTA-AM or a ROS scavenger. These results suggest that [$Ca^{2+}$]-dependent generation of intracellular ROS, at least in part, play an important role in MTX-stimulated cellular responses, such as activation of tTGase, ERK phosphorylation, and induction of cell death, in human umbilical vein endothelial cells.

• 마이크로전자및패키징학회지
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• 제24권2호
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• pp.37-41
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• 2017

$Cu_2O$는 초저가 태양전지의 흡수층으로 적용될 수 있는 물질 중 하나로 direct band gap($E_g={\sim}2.1eV$)을 갖고 있으며 최대 650 nm 파장의 빛을 흡수 할 수 있는 높은 흡수율을 가지고 있다. 또한 무독성, 풍부한 매장량으로 낮은 비용 등의 여러 장점을 가지며 간단하고 저렴한 방법으로 대량으로 제작이 가능하다. 본 연구에서 Au가 증착된 $SiO_2/Si$ 기판 위에 전착법을 통해 $Cu_2O$ 박막을 제작하였다. 우리는 용액의 pH와 작업전극에 인가되는 전위, 용액의 온도와 같은 공정조건을 바꾸어주었고 최종적으로 XRD와 SEM 사진 분석을 통해 박막의 특성을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.309-309
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• 2010

We have investigated the effect of $H_2$ plasma treatment on the BZO (ZnO:B, Boron doped ZnO) thin films. The BZO thin films are prepared by LP-MOCVD (Low Pressure Metal Organic Chemical Vapor Deposition) technique and the samples of BZO thin film are performed with $H_2$ plasma treatment by plasma treatment system with 13.56 MHz as RIE (Reactive Ion Etching) type. After exposing $H_2$ plasma treatment, measurement of transmittance, reflectance and haze spectra in 300~1100 nm, electrical properties as resistivity, mobility and carrier concentration and work function was analysed. Regarding the results of the $H_2$ plasma treatment on the BZO thin films are application to the TCO for solar cells, such as the a-Si thin films solar cell.