• Macromolecular Research
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• 제8권6호
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• pp.276-284
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• 2000

A wettability chemogradient on poly(L-lactide-co-glycolide) (PLGA) films was prepared by treating the films in air with corona from a knife-type electrode whose power increases gradually along the sample length. The PLGA surfaces oxidized gradually with the increasing corona power, and the wettability chemogradient was created on the surfaces as evidenced by the measurement of water contact angles and electron spectroscopy for chemical analysis. The wettability chemogradient PLGA surfaces were used to investigate the interaction of four different types of cells such as hepatoma (Hep G2), osteoblast (MG 63), bovine aortic endothelial (CPAE), and fibroblast (NIH/3T3) cells in terms of the surface hydrophilicity/hydrophobicity of PLGA. The cells adhered and grown on the chemogradient surface along the sample length were counted and observed by scanning electron microscopy. It was observed that the cells were adhered, spread, and grown more onto the positions with moderate hydrophilicity of the wettability chemogradient PLGA surface than the more hydrophobic or hydrophillic positions, regardless of the cell types used. The maximum adhesion and growth of the cells appeared at around water contact angles of 53～55°. This result seems closely related with the serum protein adsorption on the surface; the serum proteins were also adsorbed more onto the positions with moderate hydrophilicity of the wettability chemogradient surface. It seems that the wettability plays important roles for cell adhesion, spreading and growth on the PLGA surface. The surface modification technique used in this study may be applicable tothe area of tissue engineering for the improvement of tissue compatibility of films- or scaffold-type substrates.

• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.749-755
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• 2001

High Electromagnetic Field (EMF) with an intensity of 1 mT (Tesla) inhibited the growth of both human normal lung and immune T cell down to $20-30\%$, compared to that of an unexposed case. The human T-cells, Jurkat, were more severely affected by EMF than the human lung cells, which showed a relatively slow cell growth and substantial releas of $Ca^+2$ (3.5 times higher than the human T-cells). However, the growth of hepatoma carcinoma, Hep3B, was enhanced by twice that of an unexposed case. The EMF intensity and exposure time did not affect the growth of the cancer cells very much, while it significantly affected the growth of normal cells. Accordingly, it is possible that EMFs may play a role in the initiation of cancer. The EMFs disturbed the signal transduction and membrane systems, such that a five times higher amount of PKC-${\alpha}$ was released from the cell membrane than in the control. Extended exposure to EMFs, for more than 48 hours, also led to 1 $90\%$ necrotic death pattern from apoptotic cell death. Finally, EMF at an intensity of 1mT with a 24-T exposure promoted the differentiation of HL-60 cells to monocytes/macrophages, possibly causing potential acute leukemia.

• 생명과학회지
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• 제15권1호
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• pp.38-44
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• 2005

B형 간염 바이러스(HBV)에 의한 감염은 인류의 보건에 대단히 중요한 문제이며, 따라서 HBV에 대한 많은 연구가 수행되어져 왔다. 그러나 HBV 연구에 있어서의 주된 장애요인은 그 감염이 사람과 일부 영장류에 국한된다는 점이다. 본 연구에서는 마우스 간암 세포주인 Hepa-1c1c7 세포를 이용하여 HBV의 감염성 및 그에 따른 염증성 사이토카인인 TNF-a의 발현의 변화를 측정하였다. HBV의 표면항원(HBsAg)분비는 microparticle enzyme immunoassay를 사용하여 측정하였고, TNF-a mRNA 발현 측정에는 quantitative competitive RT-PCR 방법을 사용하였다. HBV 발현 벡터를 Hepa-1clc7 세포에 도입시켰을 경우뿐만 아니라 HBV 비리온을 갖고 있는 혈청을 사용하여 Hepa-lc1c7 세포를 감염시켰을 때에도 HBV mRNA 발현 및 HBsAg 분비가 측정되었다. 또한 두 상황 모두에서 TNF-a mRNA발현이 증가됨을 알 수 있었다. 이러한 결과는 사람과 영장류에 특이적인 HBV가 마우스 간암 세포주인 Hepa-lclc7 세포도 감염시킬 수 있다는 가능성을 제시한다. 또한 마우스 기원의 Hepa-lclc7 세포에서도 HBV의 유전자 발현에 필요한 여러 인자들이 존재하며, TNF-a와 같은 사이토카인 유전자 발현을 조절하는 세포 내 기전에 HBV가 영향을 미친다고 할 수 있다. 따라서 마우스 간암 세포주인 Hepa-lclc7 세포는 HBV 연구를 위한 시험 관내 모델로서 사용되어질 수 있을 것으로 보인다.

• 대한핵의학회지
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• 제38권1호
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• pp.62-73
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• 2004

목적: 단순 헤르페스 제 1형 티미딘 키나제(herpes simplex virus type 1 thymidine kinase gene: HSV1-tk)는 GCV와 함께 유전자치료의 한 방법으로서 가장 활발하게 연구되어왔으며, HSV1-tk 효소에 대한 다양한 기질들이 연구되어서 이를 보고 기질로 한 비침습적인 HSV1-tk 유전자 영상시스템에서 가장 널리 사용되고 있다. 본 연구에서는 보고기질로서 방사성 요오드가 표지된 5-iodovinyl-2-deoxyuridine (IVDU) and 5 -iodovinyl-2-fluoro-2-deoxyuridine (IVFRU)를 보고 기질로 하여 HSV1-tk 유전자 영상시스템에서의 유용성을 확인하고자 하였다. 대상 및 방법 HSV1-tk 유전자 영상을 위하여 HSV1-tk 유전자를 레트로 바이러스 벡터를 이용하여 Morris hepatoma 세포주(MCA-tk)에 이입한 세포주를 제조하였으며, HSV1-tk 유전자의 발현을 확인하기 위하여 Northern blotting과 Western Blotting을 시행하였다. 대조세포주인 MCA와 제조된 MCA-tk 세포주에 방사표지 IVDU와 IVFRU를 이용하여 480분까지 세포내 섭취율을 평가하였으며, 또한 MCA-tk 세포주의 백분율을 증가시키면서 이에 따른 IVDU와 IVFRU의 섭취율을 평가함으로서 섭취율과 세포수와의 상관관계를 평가하였다. 결과: MCA-tk 세포주에서 HSV1-tk의 mRNA의 발현과 HSV1-TK 단백질의 발현을 확인하였다. 방사성 요오드 표지 IVDU와 IVFRU 모두는 MCA 세포주에서는 아주 낮은 섭취율을 나타내었으며, MCA-tk 세포주에서는 모두 증가된 섭취를 보였다. IVDU가 480분에서 IVFRU보다 4배 높은 섭취를 나타내었다(p<0.01). 방사표지 IVDU와 IVFRU 모두에서 MCA-tk의 백분율의 증가에 따라서 직선적인 상관관계($R^2>0.96$)를 나타내었다. 결론: 방사성 요오드 표지 IVDU와 IVFRU는 HSV1-tk유전자가 이입된 간암세포주에서 모두 특이적인 높은 섭취율을 나타내고 직선적인 상관관계가 나타나서 두 기질 모두 HSV1-tk유전자 영상시스템에서 보고 기질로서 유용하게 사용될 수 있을것으로 기대된다.

• 대한한방내과학회지
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• 제22권1호
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• pp.87-93
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• 2001

A human hepatoma cell line, Hep G2 cells, is reliable for the study of alcohol-induced hepatotoxicity. The aim of this study is to determine the relationship between TNF-${\alpha}$, IL-$1{\alpha}$ production and EtOH-induced cytotoxicity on Hep G2 cells. The cells were incubated with EtOH in the presence of Artemisia Capillaris Herba(AC) for 24 hours and in the absence of AC for 48 hours. Cytoviability and cytokines release were analyzed by MTT assay and enzyme linked immunosorbent assay (ELISA), respectively. After 24 hours of EtOH exposure, the cytoviability had markedly decreased, and the release of cytokines had increased. The increased amount of cytokines contributed to EtOH-induced cytotoxicity. Anti-TNF-${\alpha}$ and IL-$1{\alpha}$ antibodies almost abolished it. Interestingly, EtOH-induced cytotoxicity and cytokines production were inhibited by AC. Moreover, when AC was used in combination with antibodies, there was a marked inhibition of EtOH-induced cytotoxicity. These results suggest that EtOH-induced cytotoxicity may regulate, by various factors, and AC may prevent the cytotoxicity through partial inhibition of the $TNF-{\alpha}$ and IL-$1{\alpha}$ secretion.

• 생명과학회지
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• 제22권1호
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• pp.117-125
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• 2012

본 연구는 굴 가수분해물의 간 보호 효과를 확인하는 것을 목표로 하였다. 굴은 많은 기능적 요소를 가지고 있다고 알려져 있으며 특히, 효소에 의해 생산된 가수분해물은 우수한 기능적 물질을 포함한다. 타크린으로 유발한 간세포 독성에 대한 효소별 굴 가수분해물의 보호 효과를 확인하기 위하여 HepG2세포를 이용하여 in vitro상에서 확인하였다. 사용한 샘플은 Neutrase, Flavourzyme, Protamex을 이용하여 효소 가수분해한 것이다. 타크린으로 손상을 유발한 간세포에서는 GOT와 LDH가 증가하게 된다. 굴 효소 가수분해물을 처리한 실험군에서는 아무런 처리를 하지 않은 실험군에 비하여 높은 세포 생존율을 확인할 수 있었다. 또한 GOT와 LDH 역시 감소하는 것을 알 수 있었다. 본 연구를 통하여 타크린 독성에 대한 신약, 식품의 기초 자료를 제공할 수 있을 것으로 기대된다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6433-6438
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• 2013

In hepatocellular cancer (HCC), lack of response to chemotherapy and radiation treatment can be caused by a loss of epigenetic modifications of cancer cells. Methionine adenosyltransferase 1A is inactivated in HCC and may be stimulated by an epigenetic change involving promoter hypermethylation. Therefore, drugs releasing epigenetic repression have been proposed to reverse this process. We studied the effect of the demethylating reagent 5-aza-2'-deoxycitidine (5-Aza-CdR) on MAT1A gene expression, DNA methylation and S-adenosylmethionine (SAMe) production in the HCC cell line Huh7. We found that MAT1A mRNA and protein expression were activated in Huh7 cells with the treatment of 5-Aza-CdR; the status of promoter hypermethylation was reversed. At the same time, MAT2A mRNA and protein expression was significantly reduced in Huh7 cells treated with 5-Aza-CdR, while SAMe production was significantly induced. However, 5-Aza-CdR showed no effects on MAT2A methylation. Furthermore, 5-Aza-CdR inhibited the growth of Huh7 cells and induced apoptosis and through down-regulation of Bcl-2, up-regulation of Bax and caspase-3. Our observations suggest that 5-Aza-CdR exerts its anti-tumor effects in Huh7 cells through an epigenetic change involving increased expression of the methionine adenosyltransferase 1A gene and induction of S-adenosylmethionine production.

• Archives of Pharmacal Research
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• 제27권3호
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• pp.305-313
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• 2004

The effect of diazoxide, a $K^{+}$channel opener, on apoptotic cell death was investigated in HepG2 human hepatoblastoma cells. Diazoxide induced apoptosis in a dose-dependent manner and this was evaluated by flow cytometric assays of annexin-V binding and hypodiploid nuclei stained with propidium iodide. Diazoxide did not alter intracellular $K^{+}$concentration, and various inhibitors of $K^{+}$channels had no influence on the diazoxide-induced apoptosis; this implies that $K^{+}$channels activated by diazoxide may be absent in the HepG2 cells. However, diazoxide induced a rapid and sustained increase in intracellular $Ca^{2+}$ concentration, and this was completely inhibited by the extracellular $Ca^{2+}$ chelation with EGTA, but not by blockers of intracellular $Ca^{2+}$ release (dantrolene and TMB-8). This result indicated that the diazoxide-induced increase of intracellular $Ca^{2+}$ might be due to the activation of a Ca2+ influx pathway. Diazoxide-induced $Ca^{2+}$ influx was not significantly inhibited by either voltage-operative $Ca^{2+}$ channel blockers (nifedipinen or verapamil), or by inhibitors of $Na^{+}$, $Ca^{2+}$-exchanger (bepridil and benzamil), but it was inhibited by flufenamic acid (FA), a $Ca^{2+}$-permeable nonselective cation channel blocker. A quantitative analysis of apoptosis by flow cytometry revealed that a treatment with either FA or BAPTA, an intracellular $Ca^{2+}$ chelator, significantly inhibited the diazoxide-induced apoptosis. Taken together, these results suggest that the observed diazoxide-induced apoptosis in the HepG2 cells may result from a $Ca^{2+}$ influx through the activation of $Ca^{2+}$-permeable non-selective cation channels. These results are very significant, and they lead us to further suggest that diazoxide may be valuable for the therapeutic intervention of human hepatomas.

• Biomolecules & Therapeutics
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• 제12권3호
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• pp.189-193
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• 2004

Over the past several years, research efforts have been directed both at economically producing valuable substances from the wood biomass and at producing lignolytic enzymes at a lower cost. In the present study, we found that Phellinus igniarius, the basidiomycetes, secreted lignin peroxidase as a main lignolytic enzyme, which was detected maximum activity at 16th day of culture and showed 37 kDa of molecular mass in identification by activity assay and purification by anion-exchange chromatography. The Phellinus igniarius-derived lignin peroxidase hydrolyzed steam-exploded wood (Quercus mongolica) powder into small molecules showing cytotoxicity against cancer cel1s (HepG2 hepatoma, SK-N-SH neuroblastoma, B16 melanoma, MBT-2 bladder cancer). In addition, the enzyme hydrlysates of lignins (ELg) that were extracted from the steam-exploded oak showed more potent cytotoxic effects on the cancer cells than the enzyme hydrolysates of wood biomass (EWp), indicating that the cytotoxic effect of EWp may be due to the enzyme-degraded products of lignin among the lignocellulosics. Furthermore, the cytotoxic effect of ELg on Chang, normal liver cells, was much less potent than that of ELg on HepG2 and B16 cancer cells, indicating that the cytotoxic effect of ELg may be specific for cancer cells. The present results suggest that Phellinus igniarius may be a useful resource for the large-scale production of lignin peroxidase and that the lignin peroxidase may be applied for the generation of valuable biodegradation products from wood lignocellulosics for medical use.

• 동의생리병리학회지
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• 제19권6호
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• pp.1594-1598
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• 2005

Scopoletin (6-methoxy-7-hydrorycournarin) is a phenolic coumarin and a member of the phytoalexins. In this study we investigated whether scopoletin causes apoptosis in human hepatoma HepG2 cells and, if so, by what mechanisms. We report that scopoletin induced apoptosis as confirmed by a chromatin condensation. The signal cascade acivated by scopoletin included the activation of caspase-3 as evidenced by increased pretense activity. Activation of caspase-3 resulted in the cleavage of 116 kDa poly(ADP-ribose) polymerase (PARP) to 85 kDa cleavage product in a dose-dependent fashion. Also, scopoletin-induced apoptotic mechanism of HepG2 cells involved the generation of hydrogen peroxide. Taken together, these results suggest that scopgletin induces hydrogen peroxide generation, which, in turn, causes activation of caspase-3, degradation of PARP, and eventually leads to apoptotic cell death in HepG2 cells.