• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.3
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• pp.900-907
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• 2004

The antiproliferative effect of the water extract of the branch and root bark of Ulmi Pumilae Cortex(WEUPC) was investigated on the p53-negative human leukemia cell line (HL-60). A dose- and time-dependent inhibition of cell growth was observed; this effect appears to be due to induction of apoptosis. Involvement of oxidative stress is indicated by a dose-dependent increase in intracellular reactive oxygen species levels. In addition. anti-apoptic effect was observed in the cells simultaneously treated with WEUPC and the anti-oxidant N-acetylcysteine. WEUPC did not affect the anti-apoptotic Bcl-2 and the pro-apoptotic Bax, whereas p21/sup WAF1/CIPl/ was enhanced in a dose- and time-dependent fashion; this effect was partially inhibited by N-acetylcysteine. The increase in p21/sup WAF1/CIPl/ was accompanied by a parallel accumulation of cells in the G1 phase of the cycle. These results suggest that the p53-independent induction of p21/sup WAF1/CIP/ and the induction of apoptosis may mediate the anti proliferative effect of WEUPC at least in this study; on the basis of this observation, WEUPC could be proposed as an useful adjunct to the treatment of p53-deficient tumors, which are often refractory to standard chemotherapy.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.19
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• pp.8225-8228
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• 2014

Glioma is one of the most common tumors in China and chemotherapy is critical for its treatment. Recent studies showed that benzyl isothiocyanate (BITC) could inhibit the growth of glioma cells, but the mechanisms are not fully understood. This study explored the inhibitory effect of BITC on invasion and angiogenesis of U87MG human glioma cells in vitro and in vivo, as well as potential mechanisms. It was found that BITC could inhibit invasion and angiogenesis of human glioma U87MG cells by inducing cell cycle arrest at phase G2/M. It also was demonstrated that BITC decreased expression of cyclin B1, p21, MMP-2/9, VE-cadherin, CD44, CXCR4 and MTH1, the activity of the telomerase and $PKC{\zeta}$ pathway. Microarray analysis was thus useful to explore the potential target genes related to tumorigenic processes. BITC may play important roles in the inhibition of invasion and angiogenesis of human glioma cells.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.287-294
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• 2014

The transcription factor E2F1 is active during G1 to S transition and is involved in the cell cycle and progression. A recent study reported that increased E2F1 is associated with DNA damage and tumor development in several tissues using transgenic models. Here, we show that E2F1 expression is regulated by tristetraprolin (TTP) in prostate cancer. Overexpression of TTP decreased the stability of E2F1 mRNA and the expression level of E2F1. In contrast, inhibition of TTP using siRNA increased the E2F1 expression. E2F1 mRNA contains three AREs within the 3'UTR, and TTP destabilized a luciferase mRNA that contained the E2F1 mRNA 3'UTR. Analyses of point mutants of the E2F1 mRNA 3'UTR demonstrated that ARE2 was mostly responsible for the TTP-mediated destabilization of E2F1 mRNA. RNA EMSA revealed that TTP binds directly to the E2F1 mRNA 3'UTR of ARE2. Moreover, treatment with siRNA against TTP increased the proliferation of PC3 human prostate cancer cells. Taken together, these results demonstrate that E2F1 mRNA is a physiological target of TTP and suggests that TTP controls proliferation as well as migration and invasion through the regulation of E2F1 mRNA stability.

• Proceedings of the KSAR Conference
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• 2001.03a
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• pp.16-16
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• 2001

Apoptosis로 일컬어지는 예정된 세포사멸(programmed cell death)은 개별 세포의 입장에서는 곧바로 사멸을 의미하지만, 정상적인 고등 생물의 입장에서는 개체의 발생과 분화하는데 프로그램된 과정이다. 자발적 세포사멸은 다른 조직에 비해 생식 조직인 난소나 정소에서 복잡한 apoptosis 기작들을 가지리라 사료된다. 본 연구는 Bcl-2 family중 apoptotic protein인 Bax에 대해 suppression하는 유전자를 yeast system을 활용하여 돼지 정소와 난소로부터 각각 cDNA library를 구축한 후 탐색하였다. 탐색에 활용된 cDNA library는 돼지의 정소와 난소로부터 mRNA를 분리하여 yeast vector인 pAD-GAL4-2.1에 구축하였고, 마우스 bax 유전자는 gal 1 promoter의 조절 하에 glucose 배지에서는 유도되지 않고, galactose 배지에서만 선택적으로 Bax를 발현할 수 있는 효모 vector(pL19-bax)를 구축하였다. Bax에 의한 apoptosis suppressor를 탐색하기 위해 우선 효모 W303에 pL19-bax를 transform하여 glucose 배지에서 Bax의 발현을 억제하였다. pL19-bax를 가진 효모에 정소와 난소로부터 구축된 cDNA library를 transform 시키고, transform된 효모는 각각 Bax에 의한 toxicity를 저해하는 유전자를 찾기 위해 스크린되었다. 이러한 방법으로 정소 cDNA library 탐색에서는 5 $\times$ $10^{6}$ transformant중 39개, 난소cDNA library 탐색에서는 2 $\times$ $10^{6}$ transformant중 26개의 콜로니가 생존하였다. 이들 콜로니로부터 유전자를 분리하여 분석해 본 결과 여러 그룹으로 분류할 수 있었다. 각 그룹의 관련 유전자는 protein synthesis/degradation 12종, oxidation/reductation 5종, detoxin/ cell cycle promoter 3종, signal transduction/growth factor 5종, 그리고 알려지지 않은 유전자 9종이었다. 그 중, bax-toxicity inhibition에 강력한 survival phenotype을 가지는 유전자(pSEDL)를 동정하였다. 이것은 T3-4-1 콜로니로부터 분리하였는데 140개 아미노산으로 이루어진 인간 SEDL(GenBank, XM_013096) 유전자와 매우 유사한 homology를 가지며, bax와 관련된 기능은 밝혀져 있지 않다. 이외에도 분리된 유전자에는 NADH, thioreduction, 그리고 cytochrome oxidase와 같은 positive 유전자 군이 크로닝되어, Bax를 이용한 효모에서 apoptosis suppressor에 관련된 유전자를 손쉽게 스크린하는 것이 가능하고, 분리된 유전자의 기능을 예측할 수 있어 지금까지 보고된 유전자 크로닝법 보다는 강력한 수단으로 활용될 수 있다는 사실을 시사하였다. 그러나, ORF에 관계없이 Bax 발현에 저항하는 유전자군이 선발된다든지 하는 문제점은 금후 검토가 필요하리라 사료된다.

• Reproductive and Developmental Biology
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• v.38 no.2
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• pp.79-84
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• 2014

MicroRNAs (miRNAs) are approximately 22 nucleotides of small noncoding RNAs that control gene expression at the posttranscriptional level through translational inhibition and destabilization of their target mRNAs. The miRNAs are phylogenetically conserved and have been shown to be instrumental in a wide variety of key biological processes including cell cycle regulation, apoptosis, metabolism, imprinting, and differentiation. Recently, a paper has shown that expression of the miRNA-302/367 cluster expressed abundantly in mouse and human embryonic stem cells (ESCs) can directly reprogram mouse and human somatic cells to induced pluripotent stem cells (iPSCs) efficiently in the absence of any of the four factors, Oct4, Sox2, c-Myc, and Klf4. To apply this efficient method to porcine, we analyzed porcine genomic sequence containing predicted porcine miRNA-302/367 cluster through ENSEMBL database, generated a non-replicative episomal vector system including miRNA-302/367 cluster originated from porcine embryonic fibroblasts (PEF), and tried to make porcine iPSCs by transfection of the miRNA-302/367 cluster. Colonies expressing EGFP and forming compact shape were found, but they were not established as iPSC lines. Our data in this study show that pig miRNA-302/367 cluster could not satisfy requirement of PEF reprogramming conditions for pluripotency. To make pig iPSC lines by miRNA, further studies on the role of miRNAs in pluripotency and new trials of transfection with conventional reprogramming factors are needed.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8079-8083
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• 2016

Metformin is an oral anti-hyperglycemic agent, which is the most commonly prescribed medication in the treatment of type-2 diabetes mellitus. It is purportedly associated with a reduced risk for various cancers, mainly exerting anti-proliferation effects on various human cancer cell types, such as pancreas, prostate, breast, stomach and liver. This mini-review highlights the risk and benefit of metformin used for cholangiocarcinoma (CCA) prevention and therapy. The results indicated metformin might be a quite promising strategy CCA prevention and treatment, one mechanism being inhibition of CCA tumor growth by cell cycle arrest in both in vitro and in vivo. The AMPK/mTORC1 pathway in intrahepatic CCA cells is targeted by metformin. Furthermore, metformin inhibited CCA tumor growth via the regulation of Drosha-mediated expression of multiple carcinogenic miRNAs. The use of metformin seems to be safe in patients with cirrhosis, and provides a survival benefit. Once hepatic malignancies are already established, metformin does not offer any therapeutic potential. Clinical trials and epidemiological studies of the benefit of metformin use for CCA should be conducted. To date, whether metformin as a prospective chemotherapeutic for CCA is still questionable and waits further atttention.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.3711-3719
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• 2016

Drawbacks of conventional cancer treatments, with lack of specificity and cytotoxicity using current approaches, underlies the necessity for development of a novel approach, gene-directed cancer therapy. This has provided novel technological opportunities in vitro and in vivo. This review focuses on a member of an apoptosis inhibitor family, survivin, as a valuable target. Not only the gene but also its promoter are applicable in this context. This article is based on a literature survey, with especial attention to RNA interference as well as tumor-specific promoter action. The search engine and databases utilized were Science direct, PubMed, MEDLINE and Google. In addition to cell-cycle modulation, apoptosis inhibition, interaction in cell-signaling pathways, cancer-selective expression, survivin also may be considered as specific target through its promoter as a novel treatment for cancer. Our purpose in writing this article was to create awareness in researchers, emphasizing relation of survivin gene expression to potential cancer treatment. The principal result and major conclusion of this manuscript are that survivin structure, biological functions and applications of RNA interference systems as well as tumor-specific promoter activity are of major interest for cancer gene therapy.

• BMB Reports
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• v.36 no.2
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• pp.223-229
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• 2003

The product of a tree (Tabebuia avellanedae) from South America, $\beta$-lapachone, is known to exhibit various pharmacological properties, the mechanisms of which are poorly understood. The aim of the present study was to further elucidate the possible mechanisms by which $\beta$-lapachone exerts its anti-proliferative action in cultured human prostate cancer cells. We observed that the proliferation-inhibitory effect of $\beta$-lapachone was due to the induction of apoptosis, which was confirmed by observing the morphological changes and cleavage of the poly(ADP-ribose) polymerase protein. A DNA flow cytometric analysis also revealed that $\beta$-lapachone arrested the cell cycle progression at the G1 phase. The effects were associated with the down-regulation of the phosphorylation of the retinoblastoma protein (pRB) as well as the enhanced binding of pRB and the transcription factor E2F-1. Also, $\beta$-lapachone suppressed the cyclindependent kinases (Cdks) and cyclin E-associated kinase activity without changing their expressions. Furthermore, this compound induced the levels of the Cdk inhibitor $p21^{WAF1/CIP1}$ expression in a p53-independent manner, and the p21 proteins that were induced by $\beta$-lapachone were associated with Cdk2. $\beta$-lapachone also activated the reporter construct of a p21 promoter. Overall, our results demonstrate a combined mechanism that involves the inhibition of pRB phosphorylation and induction of p21 as targets for $\beta$-lapachone. This may explain some of its anticancer effects.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.17
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• pp.7043-7048
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• 2014

Inhibition of heat shock protein 90 (Hsp90) leads to inappropriate processing of proteins involved in DNA damage repair pathways after DNA damage and may enhance tumor cell radio- and chemotherapy sensitivity. To investigate the potentiation of antitumor efficacy of lidamycin (LDM), an enediyne agent by the Hsp90 inhibitorgeldanamycin (GDM), and possible mechanisms, we have determined effects on ovarian cancer SKOV-3, hepatoma Bel-7402 and HepG2 cells by MTT assay, apoptosis assay, and cell cycle analysis. DNA damage was investigated with H2AX C-terminal phosphorylation (${\gamma}H2AX$) assays. We found that GDM synergistically sensitized SKOV-3 and Bel-7402 cells to the enediyne LDM, and this was accompanied by increased apoptosis. GDM pretreatment resulted in a greater LDM-induced DNA damage and reduced DNA repair as compared with LDM alone. However, in HepG2 cells GDM did not show significant sensitizing effects both in MTT assay and in DNA damage repair. Abrogation of LDM-induced $G_2/M$ arrest by GDM was found in SKOV-3 but not in HepG2 cells. Furthermore, the expression of ATM, related to DNA damage repair responses, was also decreased by GDM in SKOV-3 and Bel-7402 cells but not in HepG2 cells. These results demonstrate that Hsp90 inhibitors may potentiate the antitumor efficacy of LDM, possibly by reducing the repair of LDM-induced DNA damage.

• Atmosphere
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• v.24 no.4
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• pp.457-470
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• 2014

Thermodynamic conditions related with localized torrential rainfall in the middle west region of Korean peninsula are examined using radar rain rate and radiosonde observational data. Localized torrential rainfall events in this study are defined by three criteria base on 1) any one of Automated Synoptic Observing System (ASOS) hourly rainfall exceeds $30mmhr^{-1}$ around Osan, 2) the rain (> $1mmhr^{-1}$) area estimated from radar reflectivity is less than $20,000km^2$, and 3) the rain (> $10mmhr^{-1}$) cell is detected clearly and duration is short than 24 hr. As a result, 13 cases were selected during the summer season of 10 years (2004-13). It was found that the duration, the maximum rain area, and the maximum volumetric rain rate of convective cells (> $30mmhr^{-1}$) are less than 9hr, smaller than $1,000km^2$, and $15,000{\sim}60,000m^3s^{-1}$ in these cases. And a majority of cases shows the following thermodynamic characteristics: 1) Convective Available Potential Energy (CAPE) > $800Jkg^{-1}$, 2) Convective Inhibition (CIN) < $40Jkg^{-1}$, 3) Total Precipitable Water (TPW) ${\approx}$ 55 mm, and 4) Storm Relative Helicity (SRH) < $120m^2s^{-2}$. These cases mostly occurred in the afternoon. These thermodynamic conditions indicated that these cases were caused by strong atmospheric instability, lifting to overcome CIN, and sufficient moisture. The localized torrential rainfall occurred with deep moisture convection result from the instability caused by convective heating.