• Molecules and Cells
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• v.24 no.3
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• pp.431-436
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• 2007

Stem cell-based therapy is being considered as an alternative treatment for cardiomyopathy. Hence understanding the basic molecular mechanisms of cardiomyocyte differentiation is important. Besides BMP or Wnt family proteins, $TGF-{\beta}$ family members are thought to play a role in cardiac development and differentiation. Although $TGF-{\beta}$ has been reported to induce cardiac differentiation in embryonic stem cells, the differential role of $TGF-{\beta}$ isoforms has not been elucidated. In this study, employing the DMSO-induced cardiomyocyte differentiation system using P19CL6 mouse embryonic teratocarcinoma stem cells, we investigated the $TGF-{\beta}$-induced signaling pathway in cardiomyocyte differentiation. $TGF-{\beta}1$, but not the other two isoforms of $TGF-{\beta}$, was induced at the mRNA and protein level at an early stage of differentiation, and Smad2 phosphorylation increased in parallel with $TGF-{\beta}1$ induction. Inhibition of $TGF-{\beta}1$ activity with $TGF-{\beta}1$-specific neutralizing antibody reduced cell cycle arrest as well as expression of the CDK inhibitor $p21^{WAF1}$. The antibody also inhibited induction of the cardiac transcription factor Nkx2.5. Taken together, these results suggest that $TGF-{\beta}1$ is involved in cardiomyocyte differentiation by regulating cell cycle progression and cardiac gene expression in an autocrine or paracrine manner.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.4
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• pp.1186-1191
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• 2004

The root of Saussurea lappa includes sesquiterpene lactones such as costunolide and dehydrocostus lactone, and has been shown to be anti-tumorigenic with being used in traditional medicinal therapy in the Eastern Asia. However, the molecular basis of the effects of Saussurea lappa on fate of gastric carcinoma, which incur very frequently in the area, has not been well identified. In this study, the cytostatic effects of Saussurea lappa were examined using gastric AGS cancer cells. Cell viability was dramatically reduced by Saussurea lappa, in a dose-dependent manner. As time passed after its treatment, apoptotic population was increased and clearly showed G2-arrest. Being consistent, its treatment resulted in maintaining of G1 and S-phase cyclins D1, E, and A even until a significant apoptotic population was observed, for example, at 24h after treatment. However, G2/M phase cyclin B1 was reduced even at 12 h after treatment. In addition, its treatment increased expression of p53, p21/sup Wafl / cyclin dependent kinase inhibitor (CKI), and Bax, resulted in cleavages of procaspase 3 and poly ADP-ribose polymerase(PARP), indicating that such G2 arrest- and apoptosis-related molecules are involved. Therefore, these suggest that extracts of Saussurea lappa root may be a safer and effective reagent to deal with gastric cancers either by traditional herbal therapy or combinational therapy with conventional chemotherapy.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.273-276
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• 2014

Ellagic acid has been shown to inhibit tumor cell growth. However, the underlying molecular mechanisms remain elusive. In this study, our aim was to investigate whether ellagic acid inhibits the proliferation of MCF-7 human breast cancer cells via regulation of the TGF-${\beta}$/Smad3 signaling pathway. MCF-7 breast cancer cells were transfected with pEGFP-C3 or pEGFP-C3/Smad3 plasmids, and treated with ellagic acid alone or in combination with SIS3, a specific inhibitor of Smad3 phosphorylation. Cell proliferation was assessed by MTT assay and the cell cycle was detected by flow cytometry. Moreover, gene expression was detected by RT-PCR, real-time PCR and Western blot analysis. The MTT assay showed that SIS3 attenuated the inhibitory activity of ellagic acid on the proliferation of MCF-7 cells. Flow cytometry revealed that ellagic acid induced G0/G1 cell cycle arrest which was mitigated by SIS3. Moreover, SIS3 reversed the effects of ellagic acid on the expression of downstream targets of the TGF-${\beta}$/Smad3 pathway. In conclusion, ellagic acid leads to decreased phosphorylation of RB proteins mainly through modulation of the TGF-${\beta}$/Smad3 pathway, and thereby inhibits the proliferation of MCF-7 breast cancer cells.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.12
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• pp.5071-5076
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• 2014

Cholangiocarcinoma (CCA) is one of the aggressive cancers with a very poor prognosis. Several efforts have been made to identify and develop new agents for prevention and treatment of this deadly disease. In the present study, we examined the anticancer effect of luteolin on human CCA, KKU-M156 cells. Sulforhodamine B assays showed that luteolin had potent cytotoxicity on CCA cells with IC50 values of $10.5{\pm}5.0$ and $8.7{\pm}3.5{\mu}M$ at 24 and 48 h, respectively. Treatment with luteolin also caused a concentration-dependent decline in colony forming ability. Consistent with growth inhibitory effects, luteolin arrested cell cycle progression at the G2/M phase in a dose-dependent manner as assessed by flow cytometry analysis. Protein expression of cyclin A and Cdc25A was down-regulated after luteolin treatment, supporting the arrest of cells at the G2/M boundary. Besides evident G2/M arrest, luteolin induced apoptosis of KKU-M156 cells, demonstrated by a distinct sub-G1 apoptotic peak and fluorescent dye staining. A decrease in the level of anti-apoptotic Bcl-2 protein was implicated in luteolin-induced apoptosis. We further investigated the effect of luteolin on JAK/STAT3, which is an important pathway involved in the development of CCA. The results showed that interleukin-6 (IL-6)-induced JAK/STAT3 activation in KKU-M156 cells was suppressed by treatment with luteolin. Treatment with a specific JAK inhibitor, AG490, and luteolin diminished IL-6-stimulated CCA cell migration as assessed by wound healing assay. These data revealed anticancer activity of luteolin against CCA so the agent might have potential for CCA prevention and therapy.

• The Korean Journal of Food And Nutrition
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• v.25 no.1
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• pp.64-68
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• 2012

It has been suggested that Helicobacter pylori(H. pylori) infections can promote the development and progression of gastric cancer through the modulation of cell cycle regulators such as $p27^{Kip1}$ and Skp2. $p27^{Kip1}$ is a cyclin-dependent kinase (CDK) inhibitor that blocks the G1/S transition necessary for cell cycle progression. Skp2 is a component of the ubiquitin ligase complex called $SCF^{Skp2}$(SKP1-Cullin-F-box), which specifically binds and promotes the degradation of $p27^{Kip1}$. A low level of $p27^{Kip1}$ and a high level of Skp2 have been reported in many types of cancers, including gastric cancer. In addition, a decrease in $p27^{Kip1}$ has been reported in H. pylori-infected specimens. However, data on Skp2 in H. pylori infections are limited. This study examines the changes in the status of Skp2 in H. pylori-infected gastric epithelial AGS cells. For this, we stimulated AGS cells with H. pylori(NCTC 11637) at the ratio of 300:1(bacterium:cell) for 6 hours. The results of an immunoprecipitation analysis, followed by a western blot, indicate that the interaction between Skp2 and 14-3-3 was elevated 3 hours after the H. pylori treatment. In addition, there was an increase in cytoplasmic Skp2 after 3 hours, whereas there was no change in the nuclear level. Since it has been reported that interaction with 14-3-3 and the subsequent cytoplasmic translocation of Skp2 can increase its protein stability, increases in the interaction with 14-3-3 and the cytoplasmic Skp2 after the H. pylori treatment can increase the level of Skp2 in AGS cells. This phenomenon may explain, at least to some extent, the mechanism underlying the relationship between H. pylori infections and gastric carcinogenesis.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.4
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• pp.243-251
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• 2006

Dideoxypetrosynol A, a polyacetylene from the marine sponge Petrosia sp., is known to exhibit significant selective cytotoxic activity against a small panel of human tumor cell lines, however, the mechanisms of which are poorly understood. In the present study, it was investigated the further possible mechanisms by which dideoxytetrosynol A exerts its anti-proliferative action in cultured human leukemia cell line U937. We observed that the proliferation-inhibitory effect of dideoxypetrosynol A was due to the induction of G1 arrest of the cell cycle and apoptosis, which effects were associated with up-regulation of cyclin D1 and down-regulation of cyclin E without any change in cyclin-dependent-kinases (Cdks) expression. Dideoxypetrosynol A markedly induced the levels of Cdk inhibitor p16/INK4a expression. Furthermore, down-regulation of phosphorylation of retinoblastoma protein (pRB) by this compound was associated with enhanced binding of pRB and the transcription factor E2F-1. The increase in apoptosis was associated with a dose-dependent up-regulation in pro-apoptotic Bax expression and activation of caspase-3 and caspase-9. Dideoxytetrosynol A decreased the levels of cyclooxygenase (COX)-2 mRNA and protein expression without significant changes in the levels of COX-1, which was correlated with a decrease in prostaglandin E2 (PGE2) synthesis. Furthermore, dideoxytetrosynol A treatment markedly inhibited the activity of telomerase, and the expression of human telomerase reverse transcriptase (hTERT), a main determinant of the telomerase enzymatic activity, was progressively down-regulated by dideoxytetrosynol A treatment in a dose-dependent fashion. Taken together, these findings provide important new insights into the possible molecular mechanisms of the anti-cancer activity of dideoxytetrosynol A.

• Biomolecules & Therapeutics
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• v.27 no.3
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• pp.283-289
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• 2019

Brain aging induces neuropsychological changes, such as decreased memory capacity, language ability, and attention; and is also associated with neurodegenerative diseases. However, most of the studies on brain aging are focused on neurons, while senescence in astrocytes has received less attention. Astrocytes constitute the majority of cell types in the brain and perform various functions in the brain such as supporting brain structures, regulating blood-brain barrier permeability, transmitter uptake and regulation, and immunity modulation. Recent studies have shown that SIRT1 and SIRT2 play certain roles in cellular senescence in peripheral systems. Both SIRT1 and SIRT2 inhibitors delay tumor growth in vivo without significant general toxicity. In this study, we investigated the role of tenovin-1, an inhibitor of SIRT1 and SIRT2, on rat primary astrocytes where we observed senescence and other functional changes. Cellular senescence usually is characterized by irreversible cell cycle arrest and induces senescence- associated ${\beta}$-galactosidase (SA-${\beta}$-gal) activity. Tenovin-1-treated astrocytes showed increased SA-${\beta}$-gal-positive cell number, senescence-associated secretory phenotypes, including IL-6 and IL-$1{\beta}$, and cell cycle-related proteins like phospho-histone H3 and CDK2. Along with the molecular changes, tenovin-1 impaired the wound-healing activity of cultured primary astrocytes. These data suggest that tenovin-1 can induce cellular senescence in astrocytes possibly by inhibiting SIRT1 and SIRT2, which may play particular roles in brain aging and neurodegenerative conditions.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.181-181
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• 2003

We have studied the mechanism of action of TCDD on CYP1A1 promoter activity in both Hepa Ⅰ and MCF-7 cells using transient transfection system with p1A1-Luc reporter gene. When HDAC inhibitors, such as trichostatin A, HC toxin and a novel HDAC inhibitor, IN2001 were cotreated with TCDD to the cells transfected with plAt-Luc reporter gene, the basal promoter activity of CYP1A1 was increased by HBAC inhibitors. Also, in MCF-7 human breast cancer cells, HDAC inhibitors, such as IN2001 and trichostatin A increased the basal activity of CYP1A1 promoter but TCDD stimulated CYP1A1 promoter activity was not changed by HDAC inhibitors. And, in stably-transfected Hepa Ⅰ cells with p1A1-Luc, HDAC inhibitors increased the basal promoter activity only Also, we have investigated the effects of HDAC inhibitors on the human breast and prostate cancer cells in terms of cell proliferation and apoptosis based on SRB assay. IN2001 as well as trichostatin A inhibited the MCF-7, MDA-MB-231, MDA-MB-468, T47D, ZR75-1, PC3 cell growth dose-dependently. The growth inhibition of these cells with HDAC inhibitors was associated with profound morphological change, which suggests the HDAC inhibitors induced apoptosis of cells. The result of cell cycle analysis after 24h exposure of IN2001 showed G2/M cell cycle arrest in MCF-7 cells and apoptosis in T47D and MDA-MB-231 cells.

• Molecules and Cells
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• v.19 no.3
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• pp.334-341
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• 2005

Plants are sessile and rely on a wide variety of growth hormones to adjust growth and development in response to internal and external stimuli. We have identified a gene, designated NAN, encoding a basic helix-loop-helix (bHLH) transcription factor that regulates cell elongation and seed germination in plants. NAN has an HLH motif in its C-terminal region but does not have any other discernible homologies to bHLH proteins. A bipartite nuclear localization signal is located close to the HLH motif. An Arabidopsis mutant, nan-1D, in which NAN is activated by the insertion of the 35S enhancer, exhibits growth retardation with short hypocotyls and curled leaves. It is also characterized by reduced seed germination and apical hook formation, symptomatic of GA deficiency or disrupted GA signaling. The phenotypic effects of nan-1D were increased by treatment with paclobutrazol (PAC), an inhibitor of gibberellic acid (GA) biosynthesis. NAN is constitutively expressed throughout the life cycle. Our observations indicate that NAN has a housekeeping role in plant growth and development, particularly in seed germination and cell elongation, and that it may modulate GA signaling.

• BMB Reports
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• v.53 no.12
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• pp.646-651
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• 2020

Bone resorption is linked to bone formation via temporal and spatial coupling within the remodeling cycle. Several lines of evidence point to the critical role of coupling factors derived from pre-osteoclasts (POCs) during the regulation of bone marrow-derived mesenchymal stem cells (BMMSCs). However, the role of glial cell-derived neurotrophic factor (GDNF) in BMMSCs is not completely understood. Herein, we demonstrate the role of POC-derived GDNF in regulating the migration and osteogenic differentiation of BMMSCs. RNA sequencing revealed GDNF upregulation in POCs compared with monocytes/macrophages. Specifically, BMMSC migration was inhibited by a neutralizing antibody against GDNF in pre-osteoclast-conditioned medium (POC-CM), whereas treatment with a recombinant GDNF enhanced migration and osteogenic differentiation. In addition, POC-CM derived from GDNF knock-downed bone marrow macrophages suppressed BMMSC migration and osteogenic differentiation. SPP86, a small molecule inhibitor, inhibits BMMSC migration and osteogenic differentiation by targeting the receptor tyrosine kinase RET, which is recruited by GDNF into the GFRα1 complex. Overall, this study highlights the role of POC-derived GDNF in BMMSC migration and osteogenic differentiation, suggesting that GDNF regulates bone metabolism.