• Biomolecules & Therapeutics
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• 제19권2호
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• pp.174-180
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• 2011

Experiments were carried out to determine the role of Raf-1 kinase in the development of drug resistance to paclitaxel in v-H-ras transformed NIH 3T3 fibroblasts (Ras-NIH 3T3). We established a multidrug-resistant cell line (Ras-NIH 3T3/Mdr) from Ras-NIH 3T3 cells by stepwise increases in paclitaxel. Drug sensitivity assays indicated that the $IC_{50}$ value for drug-resistant Ras-NIH 3T3/Mdr cells was more than 1 ${\mu}M$ paclitaxel, 10- or more-fold higher than for the parental Ras-NIH 3T3 cells. Western blot and RT-PCR analysis showed that the drug efflux pump a P-glycoprotein were highly expressed in Ras-NIH 3T3/Mdr cells, while not being detectable in Ras-NIH 3T3 cells. Additionally, verapamil, which appears to inhibit drug efflux by acting as a substrate for P-glycoprotein, completely reversed resistance to paclitaxel in Ras-NIH 3T3/Mdr cell line, indicating that resistance to paclitaxel is associated with overexpression of the multidrug resistance gene. Interestingly, Ras-NIH 3T3/Mdr cells have higher basal Raf-1 activity compared to Ras-NIH 3T3 cells. Unexpectedly, however, the colocalization of Raf-1 and its negative regulator Spry2 was less observed in cytoplasm of Ras-NIH 3T3/Mdr cells due to translocation of Spry2 around the nucleus in the perinuclear zone, implying that Raf-1 may be released from negative feedback inhibition by interacting with Spry2. We also showed that shRNA-mediated knockdown of Raf-1 caused a moderate increase in cell susceptibility to paclitaxel. Thus, the results presented here suggest that a Raf-1-dependent pathway plays an important role in the development of acquired drug-resistance.

• Archives of Pharmacal Research
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• 제27권8호
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• pp.845-849
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• 2004

Many studies have focused on the anticarcinogenic, antimutagenic or chemopreventive activi-ties of capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) which is a major pungent ingredient in red pepper. We have previously shown that capsaicin selectively induces apoptosis in H-ras-transformed MCF10A human breast epithelial cells but not in their normal cell counter-parts (Int. J. Cancer, 103, 475-482,2003). In this study, we investigated the possible roles of reactive oxygen species (ROS) and Rac1 in capsaicin-induced apoptosis of H-ras MCF10A cells. Selective induction of ROS generation by capsaicin treatment was observed only in H-ras MCF10A cells. Pretreatment of H-ras MCF10A cells with an antioxidant N-acetylcysteine(NAC) significantly reversed capsaicin-induced growth inhibition, suggesting that ROS may mediate the apoptosis of H-ras-transformed cells induced by capsaicin. Rac1 was prominently activated by H-ras in MCF10A cells. Based on the studies using a wild type Rac1 and a domi-nant negative Rac1 constructs, we propose that Rac1 activity is critical for inhibitory effect of capsaicin on growth of H-ras-transformed MCF10A cells possibly through ROS generation.

• The Korean Journal of Physiology and Pharmacology
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• 제7권5호
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• pp.289-293
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• 2003

Mutations in the NF2 tumor suppressor gene cause neurofibromatosis type 2, an autosomal dominant inherited syndrome predisposed to the multiple tumors of the nervous system. Merlin, the NF2 gene product was reported to block Ras-mediated cell transformation and represses Ras-induced expression of cyclin D1. However, the potential mechanism underlying the anti-Ras function of merlin on the cyclin D1 is still unclear. In this study, we investigated whether merlin decreases Ha-ras-induced accumulation of cyclin D1 at the transcriptional level, and demonstrated that merlin suppressed Ras-induced cyclin D1 promoter activity mediated by the cyclic AMP-responsive element (CRE) in SK-N-BE(2)C neuroblastoma cells. Furthermore, we found that merlin attenuated active Ras and forskolin-induced CRE-driven promoter activity. These results suggest that the transcriptional repression of the cyclin D1 expression by merlin may contribute to the inhibition of Ras-induced cell proliferation.

• 생명과학회지
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• 제17권3호통권83호
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• pp.375-380
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• 2007

Dynamin은 여러 종류의 endocytosis 과정에서 최종적으로 endocytic vesicle을 membrane으로부터 분리하는데 중요한 역할을 하는 단백질이다. 이전의 보고에 의하면 dynamin-2는 Ras에 의해 암화된 세포에서 Ras signal의 신호 전달 단백질인 Grb2의 SH3 domain과 결합한다고 알려져 있다. 하지만 정상적인 세포 (NIH3T3)에 비해 Ras에 의해 암화된 세포 (NIH3T3(Ras))에서 이들 단백질의 발현이 높아지는지에 대해서는 아직 알려진 바가 없다. 본 연구에서는 먼저 NIH3T3 세포와 NIH3T3(Ras) 세포에서 dynamin-2와 Grb2의 단백질 발현을 보았는데, dynamin-2의 경우 NIH3T3 세포에 비해 NIH3T3(Ras) 세포에서 그 발현이 현저히 증가함을 볼 수 있었지만 Grb2의 경우 두 세포에서 발현의 차이를 관찰할 수 없었다. Competitive PCR을 이용하여 mRNA의발현정도를 확인하였을 때, 단백질 발현 정도와 마찬가지로 dynamin-2의 경우 NIH3T3(Ras) 세포에서 약 100배의 증가를 확인하였지만 Grb2의 경우 차이를 볼 수 없었다. Dynamin-2의 promoter 활성을 NIH3T3(Ras) 세포에서 관찰한 결과 start codon으로부터 300 bp에서 200 bp upstream에 dynamin-2의 promoter 활성을 조절하는 부위가 존재함을 확인할 수 있었다.

• Animal cells and systems
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• 제13권4호
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• pp.399-403
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• 2009

$p19^{ras}$ is an alternative splicing variant of the proto-oncogene c-H-ras pre-mRNA of $p21^{ras}$. In contrast to $p21^{ras}$, $p19^{ras}$ does not have a C-terminal CAAX motif that targets the plasma membrane and is localized to both the cytoplasm and nucleus. We found that $p19^{ras}$ activated the transcriptional activity of $p73{\beta}$ through protein-protein interactions in the nucleus. p73 is known to play an important role in cellular damage responses such as apoptosis. Although p73 is a structural and functional homologue of p53, p73-mediated apoptosis has not yet been clearly elucidated. In this study, we demonstrate that the interaction between $p19^{ras}$ and $p73{\beta}$ accelerated $p73{\beta}$-induced apoptosis through a caspase-3 dependent pathway. Treatment with DEVD-CHO, a caspase inhibitor, also strengthened $p73{\beta}$-mediated apoptosis through a caspase-3 dependent pathway. Furthermore, the enhanced transcriptional activity of endogenous $p73{\beta}$ by treatment with Taxol was amplified by $p19^{ras}$ overexpression, which markedly increased caspase-3 dependent apoptosis in the p53-null SAOS2 cancer cell line. Our findings indicate a functional linkage between $p19^{ras}$ and p73 in caspase-3 mediated apoptosis of cancer cells.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.737-741
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• 2004

본 연구에서는 지리정보시스템을 이용한 홍수범람에 대한 변화, 홍수범람면적, 홍수범람 위험지역을 산정하기 위해 HEC-GeoRAS 와 HEC-RAS 및 GIS Tool인 ArcView를 이용하여 경안천 유역에 이를 적용하였다. 1:5000 DEM과 경안천 수계 하천정비 기본계획상의 부도를 바탕으로 HEC-GeoRAS를 이용하여 HEC-RAS로 입력하기 위한 기하학적인 자료를 추출하였으며, 추출된 단면을 보정하기 위해 경안천 수계 하천정비기본계획상의 하천단면자료을 이용하였다. 그리고 20년, 30년, 50년, 80년, 100년 빈도별 홍수량자료를 사용하여 경안천 유역의 홍수범람을 모의하였다. 그 결과 빈도별 홍수량에 따른 홍수범람면적과 범람위험지역을 파악할 수 있었다.

• Advances in nano research
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• 제2권1호
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• pp.69-76
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• 2014

We have obtained opal-like photonic crystals based on opals and inverted opals exhibiting a shift of the selective reflection band toward longer and shorter wavelengths with respect to the diffraction band of the initial opal consisting of $SiO_2$ spheres. The contribution of frames forming three-dimensional periodic structures and that of fillers to the spectral arrangement of the diffraction bands has been determined.

• 한국환경과학회지
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• 제13권9호
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• pp.759-765
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• 2004

HEC-RAS model is used for estimation of rating-curve of Musung in Wi stream. Discharge is computed from stage estimated by HEC-RAS model, is compared with the discharge of water surface slope method. The relative deviation of observed and computed discharge is 5.37%, and shows as a good results. A rating-curve by HEC-RAS model shows better results than by water surface slope method.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.140-140
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• 2003

• Applied Microscopy
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• 제35권3호
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• pp.121-128
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• 2005

Ras 신호전달체계는 세포내 다양한 결합 분자들과 더불어 세포의 분열과 세포의 이동에 관여한다. Dynamin 단백질은 endocytosis와 분비과정에서 vesicle를 분리하는데 관여하는 것으로 알려져 있으며, 3가지 아형으로 구분된다. Dynamin I은 신경조직에서 만 발현되고, dynamin II는 모든 조직에서 발현되지만 dynamin III는 정소를 포함한 생식기계에서만 발현된다. 선행된 연구에서 NIH3T3 세포를 이용하여 ras과발현 세포주를 만들었으며, dynamin II와 ras의 신호전달체계에 있는 Grb2가 결합한다는 것을 보고하였다. 따라서, 본 연구는 ras 단백질이 과발현되는 세포 (NIH3T3 (ras))와 대조세포인 NIH3T3의 형태학적인 차이점을 분석하고, 이 두 세포들에서 dynamin II 단백질의 발현의 차이를 비교하고자 하였다. Dynamin II의 발현차이를 분석하기 위해 형광염색을 하여 공초점 레이저현미경으로 세포내 분석을 하였으며, western blot을 시행하여 생화학적인 발현차이를 보았다. 또한, 두 세포의 미세구조적인 분석을 위하여 SEM과 TEM을 사용하였다. Dynamin II는 NIH3T3 (ras) 세포에서 발현이 증가 하였으며, NIH3T3 세포에 비하여 좀더 방추형이 었으며, 작은 세포질 돌기가 세포막을 따라 다수 신장되어있음이 관찰되었다. 또한, NIH3T3 (ras) 세포의 endocytotic vesicle이 형성되는 부위에서 dynamin II의 발현이 증가하였다. 이러한 결과로 dynamin II는 ras신호전달체계의한 신호전달분자로서 작용을 할 것으로 사료된다.