• Molecules and Cells
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• 제26권5호
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• pp.462-467
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• 2008

TPA is known to cooperate with an activated Ras oncogene in the transformation of rodent fibroblasts, but the biochemical mechanisms responsible for this effect have not been established. In the present study we used c-fos promoter-luciferase constructs as reporters, in transient transfection assays, in NIH3T3 cells to assess the mechanism of this cooperation. We found a marked synergistic interaction between TPA and a transfected v-Ha-ras oncogene in the activation of c-fos promoter and SRE. SRE has binding sites for TCF and SRF. A dominant-negative Ras (ras-N17) inhibited the TPA-Ras synergy by blocking the PKC-MAPK-TCF pathway. Dominant-negative RhoA and Rac1 (but not Cdc42Hs) inhibited the TPA-Ras synergy by blocking the Ras-Rho-SRF signaling pathway. Constitutively active $PKC{\alpha}$ and $PKC{\varepsilon}$ showed synergy with v-Ras. These results suggest that the activation of two distinct pathways such as Ras-Raf-ERK-TCF pathway and Rho-SRF pathway are responsible for the induction of c-fos by TPA and Ras in mitogenic signaling pathways.

• 생명과학회지
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• 제5권3호
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• pp.105-116
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• 1995

To investigate genomic changes in c-myc gene by a chemical carcinogen, human lymphoblast NC-37 cells were exposed to benzo(a)pyrene(BP) and dimethylbenzanthracene(DMBA), and the c-myc gene expression was evaluated by Northern and Southern blot hybridization techniques. The results are as follows: When the genomic DNA of NC-37 cells exposed to several concentrations(1.25, 2.5 and 5ug/ml) of BP concentration. However, the c-myc gene was most significantly enhanced with 2.5ug/ml of BP. The expressions of c-myc gene in NC-37 cells was stimulated by BP and DMBA. Addition of TPA reduced the gene expression BP-treated cells, whereas it enhanced the gene expression in DMBA-treated cells. The expression of c-H-ras gene was slightly increased by treatment with BP and DMBA alone and in combination with TPA, however the magnitude of increase was not significantly different between each other. The expressions of c-myc c-H-ras genes in Burkitt's lymphoma cells were greater than those in NC-37 cells. When the DNA extracted from NC-37 cells exposed to various concentrations of BP were amplified by polymerase chain reaction using a primer set containing c-myc exon I, the amplified products were of the same size in all groups. To evaluate the BP toxicity in E.coli to which human c-myc gene-cloned pBR322 vector was inserted, Southern blot hybridization was conducted on c-myc genes digested with EcoRI/HindIII and Smal/Xbal restriction enzymes, and observing that in 2 ug/ml BP-treated cells a 3.5kb fragment was generated in addition to 1.3kb fragment which can be observed in normal cells. Direct nucleotide sequence analysis of polymerase chain reaction products showed a mutation of G$\longrightarrow$A transition at the Smal recognition site.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.107-107
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• 2001

During the last decade, enormous progress has been made on the biological significance of apoptosis. Since ras is among the most central molecule in signaling, we asked if ras regulates apoptotic pathway. We have previously shown that H-ras, but not N-ras, induces an invasiveness and motility in human breast epithelial cells (MCF10A), while both H-ras and N-ras induce transformed phenotype. In this study, we wished to seek a chemopreventive agent that effectively induces apoptosis in H-ras-activated cells. Here we show that capsaicin, the major pungent phytochemical in red pepper, induces caspase 3-involved apoptosis selectively in H-ras activated MCF10A cells while the parental MCF10A cells are not effected. In order to study the molecular mechanisms for the increased sensitivity of H-ras MCF10A cells to capsaicin-induced apoptosis, activation of ras downstream signaling molecules, mitogen-activated protein kinases (MAPKinases), upon capsaicin treatment was investigated. Phosphorylated forms of JNK1 and p38 MAPKinase were prominently increased whereas activated ERK-1/2 was decreased by capsaicin in ras-activated cells. The parental cells did not respond to capsaicin, suggesting that capsaicin selectively induces apoptosis through modulating activities of ras downstream signaling molecules in H-ras-activated cells. Studies using chemical inhibitors (CPT-cAMP, SB203580 and PD98059) and dominant negative constructs of JNKl, p38 and MEK show that activation of JNK1 and p38 MAPKinase, but not ERK-1/2, is critical for ras-mediated apoptosis by capsaicin.

• 한국수의병리학회:학술대회논문집
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• 한국수의병리학회 2001년도 추계학술대회 및 정기총회
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• pp.13-15
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• 2001

발암성시험연구에 사용되고 있는 형질전환 동물들은 랫드와 마우스 등이 있는데, 그 중 c-Ha-ras proto-oncogene 마우스 (ras H2 mice), v-Ha-ras 형질전환 마우스 (Tg.AC mice), pim-1 형질전환 마우스 및 p53 knockout 마우스 등이 발암유발물질에 감수성이 높아 현재 중기발암성시험에 이용되고 있다. (중략)

• Toxicological Research
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• 제17권
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• pp.293-297
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• 2001

The international pharmaceutical and regulatory communities had been recognizing the limited utility of conventional rodent carcinogenicity study particularly on the second species, mouse, after intense investigation of carcinogenicity data base worldwide, and a new scheme for carcinogenicity testing for pharmaceuticals was proposed at the Expert Working Group on Safety in the International Conference on Harmonization (ICH) in 1996. CB6F 1-Tg rasH2 mouse carrying human prototype c-Ha-ras gene with its own promoter/enhancer is one oj the new carcinogenicity assay model for human cancer risk assessment. Studies have been conducted since 1992 to validate the transgenic (Tg) mice for rapid carcinogenicity test-ing, short term (26 weeks) studies with genotoxic (by Salmonella), non-genotoxic carcinogens, genotoxic non-carcinogens, non-genotoxic non-carcinogens revealed relatively high concordance oj the response of the Tg mouse with classical bioassay across classes of carcinogenic agents. Mechanistic basis for carcinogensis in the model are being elucidated in terms of the role of overexpression and/or point mutation of the transgene. This report review the initial studies of validation of the model and preliminary results of on-going ILSI HESI ACT project will be presented.

• Bulletin of the Korean Chemical Society
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• 제19권11호
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• pp.1202-1206
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• 1998

We have explored the impact of altering the Ras-cAMP pathway on cell survival upon oxidative exposures. A hyperactivated Ras mutant of Saccharomyces cerevisiae, intrinsically more sensitive to heat shock than the wild type, was investigated with regard to oxidative stress. In this paper we report that the response of iral, ira2-deleted mutant (IR2.53) to an oxidant, such as hydrogen peroxide (H2O2) or menadione is more sensitive than that of the wild type. IR2.53 showed a dramatic decrease in survival rate when challenged with 0.1 mM H2O2 for 30 min. The greater sensitivity of IR2.53 was also noticed with treatment of 0.01 mM menadione. Prior to oxidative stresses by these oxidants, both the wild type and the mutant were preconditioned with a mild heat shock (37 ℃, 30 min), resulting in improved survivals against oxidative stresses. Rescue of IR2.53 from menadione stress by heat pretreatment was more clearly demonstrated than that from H2O2 treatment. On the other hand, no significant difference was observed between the wild type and the IR2.53 mutant in their survival rates upon paraquat treatments. These findings imply that the mechanism by which H2O2 and menadione put forth their oxidative effects may be closely associated with the cAMP-Ras pathway whereas that of paraquat is independent of the Ras pathway. Finally, the level of glutathione (GSH) was measured enzymatically as an indicator of antioxidation and compared with the survival rate. Taken all these together, this study provides an insight into a mechanism of the Ras pathway regulated by several oxidants and suggests that the Ras pathway plays a crucial role in protection of cell damage following oxidative stress.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제26권3호
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• pp.254-261
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• 2000

본 연구는 인체암 발생과 밀접한 관련을 가지고 있는 ras 종양 유전자의 발암화기전을 인체상피세포모델을 이용하여 규명하고자 SV40-Ad12 hybrid virus에 의해 불멸화된 인체상피세포모델에 H-ras 종양유전자을 함유하는 $pSV_2-ras$를 transfection하여 H-ras에 의한 세포발암화를 평가하였다. ras를 함유하는 세포군은 대조세포군에 비해 saturation density, soft-agar colony formation, cell aggregation 등의 세포 발암화지표가 유의한 수준으로 높게 나타나 H-ras에 의한 인체상피세포의 발암화를 확인하였다. 또한 H-ras에 의한 인체세포 발암화는 hydrocortisone과 같은 glucocorticoid에 의해 촉진되어 saturation density, soft-agar colony formation의 증가 및 foci의 출현시기의 단축을 나타내었다. H-ras 종양 유전자에 의한 인체세포발암화 과정에 관여하는 신호전달기작의 영향을 평가하기 위해 효현제 처리 후 세포내 칼슘농도변화를 측정한 결과 발암세포의 세포내 칼슘농도변화가 낮게 나타났으며 특히 이러한 반응차이는 세포외 칼슘의 존재하에서 더욱 뚜렷이 나타났다. 따라서 세포외부로부터 칼슘의 세포내 이동이 발암화에 의해 억제되고 있음을 보였다. 또한 효현제 처리후 $IP_3$ 농도의 변화를 측정한 결과 발암세포의 $IP_3$ 증가폭이 대조군 세포보다 훨씬 낮았다. 이러한 결과는 H-ras에 의한 세포 발암화에 phospholipase C와 관련한 신호전달기작의 down-regulation이 관여하고 있음을 보여주고 있다. 성장조절인자의 mRNA 발현을 평가한 결과 $TGF-{\beta}_1$ 및 PAI-2의 발현은 발암세포에서 낮게 나타난 반면 fibronectin의 경우는 발암세포의 발현이 높게 나타났다. 이러한 결과는 H-ras 종양유전자에 의한 발암화 과정에 성장조절인자의 변화가 관여하고 있으며 이러한 성장조절인자의 확인은 암발생의 생물학적 지표를 선별하는 데 기여할 것으로 사료된다. 본 연구는 H-ras 종양유전자에 의한 인체세포 발암화의 확인과 발암화 과정에 관여하는 신호전달기작의 변화 및 성장조절인자의 확인을 통하여 상피세포에서 나타나는 구강암 등의 발생기전 이해 뿐만 아니라 생체지표의 개발에 필요한 기초자료를 마련하는 데 기여할 것으로 사료된다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.816-820
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• 2005

본 연구에서는 해안 도시 하천의 범람으로 인한 홍수 재해 발생시 예상될 수 있는 피해에 대해 적절한 홍수예경보 및 피난대책을 수립하고자 대표적인 해안 도시 하천의 특성을 가지는 부산시 온천천 유역을 대상으로 수치지도에서 각종 지형자료를 추출하였고 수문 GIS 자료를 구축하였다. 그리고, 하천 수리 분석을 위한 한계유출량 산정을 위해 HEC-RAS 모형을 이용 조위의 영향을 고려하여 홍수위 및 한계유출량을 산정하였고 수문 분석을 위한 도시 돌발 홍수 기준 우량 산정을 위해 PCSWMM 2002를 이용하여 기준 우량을 산정하였다. 전형적인 해안 도시 지역 유역 특성을 나타내는 부산시 온천천 유역에 대한 경보발령 기준을 설정하기 위하여 선정지점 세 곳의 한계수심 $H_{c1},\;H_{c2},\;H_{c3},\;H_{c4}$가 발생할 수 있는 강우량(위험 홍수량을 유발하는 위험 강우량(Trigger Rainfall))을 산정하였고 PCSWMM을 이용한 모형화 기법으로 해안 도시 돌발 홍수 기준 우량을 산정하였다. 산정 결과 온천천 유역의 홍수예경보 시스템과 이에 따른 홍수예경보 발령흐름도, 운영체계가 결정되어 해안 도시 돌발 홍수예경보 방안이 구축되었다. 해안 도시의 홍수 관리는 도시 우수 시스템, 하천, 해안 특성이 복합된 문제이다. 현재 해안 도시 지역의 홍수예경보 시스템 구축 실적이 전무한 실정임을 볼 때 현실적으로 실용화 할 수 있는 시스템 개발을 해내는 것이 무엇보다도 시급하고 중요한 문제이다. 앞으로 더욱 심도있게 연구하여 주요 하천에 대한 홍수예경보 시스템 구축이 절실히 요구된다.

• 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.

• 한국분말재료학회지
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• 제18권3호
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• pp.297-302
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• 2011

Colloidal stability is one of crucial factors for many applications of nanodiamond. Despite recent development, nanodiamonds available on the market often exhibit a high impurity content, wide size distribution of aggregates and low resistance to sedimentation. In the current study, four commercial nanodiamond powders synthesized by detonation synthesis were surface modified and then separated with respect to the size into six fractions by centrifugation. The fractions were evaluated by zeta potential, particle size distribution and elemental composition. The results showed that the modified nanodiamonds form stable colloidal suspensions without sedimentation for a long time.