• Asian Pacific Journal of Cancer Prevention
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• 제14권2호
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• pp.685-689
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• 2013

Objective: To study the effects of down-regulation of HDAC6 expression on proliferation, cell cycling and migration of esophageal squamous cell carcinoma (ESCC) cells and related molecular mechanisms. Methods: ESCC cell line EC9706 cells were randomly divided into untreated (with no transfection), control siRNA (transfected with control siRNA) and HDAC6 siRNA (transfected with HDAC6 small interfering RNA) groups. Effects of HDAC6 siRNA interference on expression of HDAC6 mRNA and protein in EC9706 cells were investigated by semi-quantitative RT-PCR, Western blotting and immunocytochemistry methods. Effects of down-regulation of HDAC6 expression on cell proliferation, cell cycle, and cell migration were studied using a CCK-8 kit, flow cytometry and Boyden chambers, respectively. Changes of mRNA and protein expression levels of cell cycle related factor (p21) and cell migration related factor (E-cadherin) were investigated by semi-quantitative RT-PCR and Western blotting methods. Results: After transfection of HDAC6 siRNA, the expression of HDAC6 mRNA and protein in EC9706 cells was significantly downregulated. In the HDAC6 siRNA group, cell proliferation was markedly inhibited, the percentage of cells in G0/G1 phase evidently increased and the percentage of cells in S phase decreased, and the number of migrating cells significantly and obviously decreased. The mRNA and protein expression levels of p21 and E-cadherin in the HDAC6 siRNA group were significantly higher than those in the untreated group and the control siRNA group, respectively. Conclusions: HDAC6 siRNA can effectively downregulate the expression of HDAC6 mRNA and protein in EC9706 cells. Down-regulation of HDAC6 expression can obviously inhibit cell proliferation, arrest cell cycling in the G0/G1 phase and reduce cell migration. The latter two functions may be closely related with the elevation of mRNA and protein expression of p21 and E-cadherin.

• 한국통신학회논문지
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• 제25권5B호
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• pp.974-984
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• 2000

전압 강하 변환기의 구동 회로를 제안하였다. 구동 회로의 load regulation 특성을 개선하기 위하여 적응 바이어스(adaptive biasing) 개념을 제안하였고 이 개념을 도입한 NMOS 구동 회로를 설계하였다. 적응 바이어스 전류 구동 개념이 적용된 NMOS 구동 회로는 구동단에서의 밀러(Miller) 효과가 없으므로 위상 여유가 크고 안정된 주파수 특성을 보여주고 있다. NMOS 구동단은 같은 구동 전류를 흘려줄 경우 PMOS 구동단에 비해 훨씬 적은 트랜지스터 크기 비로 설계 제작이 가능하므로 칩 면적을 크게 줄일 수 있으며 PMOS 구동단에서의 같은 보상 커패시터나 보상 추로 회로가 없다. 제안된 회로는 0.8 $\mu\textrm{m}$ CMOS 공정 기술을 이용하여 구현되었으며 설계가 간단하고, 대기 전력(quiescent power)이 60 ㎼로 측정되었다. 전체 크기는 150 $\mu\textrm{m}$$\times$ 360 $\mu\textrm{m}$이고 100$\mu\textrm{A}$부터 50 ㎃ 까지의 구동 전류 변화 조건하에서 5.6 ㎷의 load regulation 값을 얻었다.

• Biomolecules & Therapeutics
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• 제23권1호
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• pp.31-38
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• 2015

Histone acetylation plays a critical role in the regulation of transcription by altering the structure of chromatin, and it may influence the resistance of some tumor cells to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) by regulating the gene expression of components of the TRAIL signaling pathway. In this study, we investigated the effects and molecular mechanisms of trichostatin A (TSA), a histone deacetylase inhibitor, in sensitizing TRAIL-induced apoptosis in Caki human renal carcinoma cells. Our results indicate that nontoxic concentrations of TSA substantially enhance TRAIL-induced apoptosis compared with treatment with either agent alone. Cotreatment with TSA and TRAIL effectively induced cleavage of Bid and loss of mitochondrial membrane potential (MMP), which was associated with the activation of caspases (-3, -8, and -9) and degradation of poly (ADP-ribose) polymerase (PARP), contributing toward the sensitization to TRAIL. Combined treatment with TSA and TRAIL significantly reduced the levels of the cellular Fas-associated death domain (FADD)-like interleukin-$1{\beta}$-converting enzyme (FLICE) inhibitory protein (c-FLIP), whereas those of death receptor (DR) 4, DR5, and FADD remained unchanged. The synergistic effect of TAS and TRAIL was perfectly attenuated in c-$FLIP_L$-overexpressing Caki cells. Taken together, the present study demonstrates that down-regulation of c-FLIP contributes to TSA-facilitated TRAIL-induced apoptosis, amplifying the death receptor, as well as mitochondria-mediated apoptotic signaling pathways.

• 정신신체의학
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• 제20권2호
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• pp.135-138
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• 2012

기능성 위장관 장애(functional gastrointestinal disorder, FGID)의 생물학적 병태생리는 아직 명확하지 않은 실정이나 최근에 뇌-장관 축(brain-gut axis, BGA) 모델이 각광받고 있다. BGA 모델은 중추신경계(CNS)와 장관신경계(ENS)가 신경계, 신경내분비계, 신경면역계 등으로 밀접하게 연계되어 양방향성으로 항상성을 유지한다는 이론이다. 또한 BGA는 FGID에 대한 항우울제 효과의 이론적 근거를 제공한다. 저자들은 세로토닌 노르에프네프린 재흡수 차단제인 duloxetine이 목 이물감, 우울감을 보이는 환자와 상부 위장관 팽만감, 건강염려증적 불안을 보이는 환자에서 위장관 증상 및 정신의학적 증상에 효과적이었음을 경험하였다. 이에 두 증례보고를 통하여 BGA에 대해서 간략히 검토하고 duloxetine의 효과를 BGA의 측면에서 고찰하였다. 이 두 증례에서 duloxetine의 장관에서 뇌로의 영향(bottom-up regulation)으로는 세로토닌 수용체, 노르에피네프린 수용체 그리고 부신피질자극호르몬방출인자(CRF) 길항효과를 통해서 내장과민성(visceral hypersensitivity) 및 정신의학적 증상을 호전시키고, 뇌에서 장관으로의 영향(top-down regulation)으로는 우울과 불안을 호전시킴으로 위장관 증상에 영향을 미친 것으로 추정해 볼 수 있다.

• Journal of Microbiology and Biotechnology
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• 제25권3호
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• pp.413-417
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• 2015

Recently, we isolated HY253, a novel decahydrofluorene analog with a molecular structure of 7,8a-divinyl-2,4a,4b,5,6,7,8,8a,9,9a-decahydro-1H-fluorene-2,4a,4b,9a-tetraol from the roots of Aralia continentalis, which is known as Dokwhal (獨活), a traditional medicinal herb. Moreover, we previously reported its cytotoxic activity on cancer cell proliferation in human lung cancer A549 and cervical cancer HeLa cells. The current study aimed to evaluate its detailed molecular mechanisms in cell cycle arrest and apoptotic induction in human hepatocellular carcinoma HepG2 cells. Flow cytometric analysis of HepG2 cells treated with $60{\mu}M$ HY253 revealed appreciable cell cycle arrest at the G1 phase via inhibition of Rb phosphorylation and down-regulation of cyclin D1. Furthermore, using western blots, we found that up-regulation of cyclin-dependent kinase inhibitors, such as p21^CIP1 and p27^KIP1, was associated with this G₁ phase arrest. Moreover, TUNEL assay and immunoblottings revealed apoptotic induction in HepG2 cells treated with $60{\mu}M$ HY253 for 24 h, which is associated with cytochrome c release from mitochondria, via down-regulation of anti-apoptotic Bcl-2 protein, which in turn resulted in activation of caspase-9 and -3, and proteolytic cleavage of poly(ADP-ribose) polymerase (PARP). Accordingly, we suggest that HY253 may be a potent chemotherapeutic hit compound for treating human liver cancer cells via up-regulation and activation of the p53 gene.

• Molecules and Cells
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• 제39권8호
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• pp.631-638
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• 2016

Glutathione peroxidase 3 (GPx3), an antioxidant enzyme, acts as a modulator of redox signaling, has immunomodulatory function, and catalyzes the detoxification of reactive oxygen species (ROS). GPx3 has been identified as a tumor suppressor in many cancers. Although hyper-methylation of the GPx3 promoter has been shown to down-regulate its expression, other mechanisms by which GPx3 expression is regulated have not been reported. The aim of this study was to further elucidate the mechanisms of GPx3 regulation. GPx3 gene analysis predicted the presence of ten glucocorticoid response elements (GREs) on the GPx3 gene. This result prompted us to investigate whether GPx3 expression is regulated by the glucocorticoid receptor (GR), which is implicated in tumor response to chemotherapy. The corticosteroid dexamethasone (Dex) was used to examine the possible relationship between GR and GPx3 expression. Dex significantly induced GPx3 expression in H1299, H1650, and H1975 cell lines, which exhibit low levels of GPx3 expression under normal conditions. The results of EMSA and ChIP-PCR suggest that GR binds directly to GRE 6 and 7, both of which are located near the GPx3 promoter. Assessment of GPx3 transcription efficiency using a luciferase reporter system showed that blocking formation of the GR-GRE complexes reduced luciferase activity by 7-8-fold. Suppression of GR expression by siRNA transfection also induced down-regulation of GPx3. These data indicate that GPx3 expression can be regulated independently via epigenetic or GR-mediated mechanisms in lung cancer cells, and suggest that GPx3 could potentiate glucocorticoid (GC)-mediated anti-infla-mmatory signaling in lung cancer cells.

• Molecules and Cells
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• 제28권6호
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• pp.565-573
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• 2009

The pig could be a useful model to characterize molecular aspects determining several delicate phenotypes because they have been bred for those characteristics. The Korean native pig (KNP) is a regional breed in Korea that was characterized by relatively high intramuscular fat content and reddish meat color compared to other western breeds such as Yorkshire (YS). YS grew faster and contained more lean muscle than KNP. We compared the KNP to Yorksire to find molecular clues determining muscle characteristics. The comparison of skeletal gene expression profiles between these two breeds showed molecular differences in muscle. We found 82 differentially expressed genes (DEGs) defined by fold change (more than 1.5 fold difference) and statistical significance (within 5% of false discovery rate). Functional analyses of these DEGs indicated up-regulation of most genes involved in cell cycle arrest, down-regulation of most genes involved in cellular differentiation and its inhibition, down-regulation of most genes encoding component of muscular-structural system, and up-regulation of most genes involved in diverse metabolism in KNP. Especially, DEGs in above-mentioned categories included a large number of genes encoding proteins directly or indirectly involved in p53 pathway. Our results indicated a possible role of p53 to determine muscle characteristics between these two breeds.

• Journal of Ginseng Research
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• 제31권1호
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• pp.1-13
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• 2007

We found that the main bacterial metabolite M1 is an active component of orally administered protopanxadiol-type ginsenosides, and that the anti-metastatic effect by oral administration of ginsenosides may be primarily mediated through the inhibition of tumor invasion, migration and growth of tumor cells by their metabolite M1. Pharmacokinetic study after oral administration of ginsenoside Rb1 revealed that M1 was detected in serum for 24 h by HPLC analysis but Rb1 was not detected. M1, with anti-metastatic property, inhibited the proliferation of murine and human tumor cells in a time- and concentration-dependent manner in vitro, and also induced apoptotic cell death (the ladder fragmentation of the extracted DNA). The induction of apoptosis by M1 involved the up-regulation of the cyclin-dependent kinase(CDK) inhibitor $p27^{Kip1}$ as well as the down-regulation of a proto-oncogene product c-Myc and cyclin D1 in a time-dependent manner. Thus, M1 might cause the cell-cycle arrest (G1 phase arrest) in honor cells through the up/down-regulation of these cell-growth related molecules, and consequently induce apoptosis. The nucleosomal distribution of fluorescence-labeled M1 suggests that the modification of these molecules is induced by transcriptional regulation. Tumor-induced angiogenesis (neovascularization) is one of the most important events concerning tumor growth and metastasis. Neovascularization toward and into tumor is a crucial step for the delivery of nutrition and oxygen to tumors, and also functions as the metastatic pathway to distant organs. M1 inhibited the tube-like formation of hepatic sinusoidal endothelial (HSE) cells induced by the conditioned medium of colon 26-L5 cells in a concentration-dependent manner. However, M1 at the concentrations used in this study did not affect the growth of HSE cells in vitro.

• Molecules and Cells
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• 제24권2호
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• pp.224-231
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• 2007

$H_2O_2$, as an example of oxidative stress, induces cardiac myocyte apoptosis. Bcl-2 family proteins are key regulators of the apoptotic response while their functions can be regulated by post-translational modifications including phosphorylation, dimerization or proteolytic cleavage. In this study, we examined the role of various protein kinases in regulating total BAD protein levels in adult rat cardiac myocytes undergoing apoptosis. Stimulation with 0.1 mM $H_2O_2$, which induces apoptosis, resulted in a marked down-regulation of BAD protein, which is attributed to cleavage by caspases since it can be restored in the presence of a general caspase inhibitor. Inhibition of PKC, p38-MAPK, ERK1/2 and PI-3-K did not influence the reduced BAD protein levels observed after stimulation with $H_2O_2$. On the contrary, inhibition of PKA or specifically $PKC{\delta}$ resulted in up-regulation of BAD. Decreased caspase 3 activity was observed in $H_2O_2$ treated cells after inhibition of PKA or $PKC{\delta}$ whereas inhibition of PKA also resulted in improved cell survival. Furthermore, addition of okadaic acid to inhibit selected phosphatases resulted in enhanced BAD cleavage. These data suggest that, during oxidative stress-induced cardiac myocyte apoptosis, there is a caspase-dependent down-regulation of BAD protein, which seems to be regulated by coordinated action of PKA, $PKC{\delta}$ and phosphatases.

• 대한화장품학회지
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• 제28권1호
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• pp.135-149
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• 2002

To date, research on the regulation of melanogenesis has focused on factors which affect tyrosinase, the rate-limiting enzyme in the melanogenic pathway, by searching for chemicals which competitively inhibit tyrosinase function. Many types of tyrosinase inhibitors have been developed, but no satisfactory results have been made clinically until now, To find a new whitening agent, which effectively inhibits melanogenesis, we synthesized several compounds and selected compounds by cell-based assay system. Finally, 3, 4, 5-trimethoxy cinnamaie thymol ester(TCTE, Melasolv) was selected and the effects of TCTE on melanogenesis were investigated. Treatment of mouse-derived melanocyte melan-a cells with TCTE results in a marked down-regulation of tyrosinase activity. 80% decrease of tyrosinase activity occurs with 30uM TCTE treatment for 72 hours without affecting cell growth. The inhibition of tyrosinase activity is dose-dependent and melanin content was also decreased to 40%. From the in vitro tyrosinase assay using cell extract, TCTE does not act as a direct inhibitor of the enzyme. Treatment of melan-a cultures with TCTE blocks the increase in tyrosinase activity by either forskolin, 3-isobutyl-1-methtyl-xanthine. TCTE decreased the expression of tyrosinase, TRP-1 without effects on TRP-2 protein expression through the down regulation of tyrosinase and TRP-1 mRNA. From the results of cAMP immunoassays, intracellular levels of the cyclin nucleotide are unaffected in cells treated with TCTE. The inhibitory effects of melanin synthesis were also shown in reconstitute human epidermis model by topical application. These findings suggest that TCTE can be used for studying the regulation of melanogenesis and depigmenting agent.