• Journal of Oral Medicine and Pain
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• v.34 no.3
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• pp.261-276
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• 2009

Lactacystin, a microbial natural product synthesized by Streptomyces, has been commonly used as a selective proteasome inhibitor in many studies. Proteasome inhibitors is known to be preventing the proliferation of cancer cells in vivo as well as in vitro. Furthermore, proteasome inhibitors, as single or combined with other anticancer agents, are suggested as a new class of potential anticancer agents. This study was undertaken to examine in vitro effects of cytotoxicity and growth inhibition, and the molecular mechanism underlying induction of apoptosis in SCC25 human tongue sqaumous cell carcinoma cell line treated with lactacystin. The viability of SCC25 cells, human normal keratinocytes (HaCaT cells) and human gingiva fibroblasts (HGF-1 cells), and the growth inhibition of SCC25 cells were assessed by MTT assay and clonogenic assay respectively. The hoechst staining, hemacolor staining and TUNEL staining were conducted to observe SCC25 cells undergoing apoptosis. SCC25 cells were treated with lactacystin, and Western blotting, immunocytochemistry, confocal microscopy, FAScan flow cytometry, MMP activity, and proteasome activity were performed. Lactacystin treatment of SCC25 cells resulted in a time- and does-dependent decrease of cell viability and a does-dependent inhibition of cell growth, and induced apoptotic cell death. Interestingly, lactacytin remarkably revealed cytotoxicity in SCC25 cells but not normal cells. And tested SCC25 cells showed several lines of apoptotic manifestation such as nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, the decrease of DNA contents, the release of cytochrome c into cytosol, the translocation of AIF and DFF40 (CAD) onto nuclei, the up-regulation of Bax, and the activation of caspase-7, caspase-3, PARP, lamin A/C and DFF45 (ICAD). Flow cytometric analysis revealed that lactacystin resulted in G1 arrest in cell cycle progression which was associated with up-regulation in the protein expression of CDK inhibitors, $p21^{WAF1/CIP1}$ and $p27^{KIP1}$. We presented data indicating that lactacystin induces G1 cell cycle arrest and apoptois via proteasome, mitochondria and caspase pathway in SCC25 cells. Therefore our data provide the possibility that lactacystin could be as a novel therapeutic strategy for human tongue squamous cell carcinoma.

• Journal of Life Science
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• v.17 no.7 s.87
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• pp.976-982
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• 2007

The purpose of this study was to determine the modulating effects of histone deacetylase inhibitor, trichostatin A, on the differentiation of mouse C2C12 myoblasts. We demonstrated that trichostatin A induced morphological changes of C2C12 myoblasts into smooth muscles and significantly increased the gene expression of smooth muscle markers including smooth muscle ${\alpha}-actin$ and transgelin. These results were due to the change in the expression level of cell cycle regulators in trichostatin A-treated C2C12 cells. Real-time PCR data revealed that cyclin dependent kinase inhibitor, p21, mRNA expression was significantly increased in trichostatin A-treated C2C12 cells. However, trichostaDn A rapidly decreased cyclin Dl mRNA expression necessary for cell cycle progression in 24hr after treatment. In conclusion, the strong inhibitory effects of trichostatin A on histone deacetylation induced transdifferentiation of C2C12 myoblasts into smooth muscle cells and these results are partly due to the changes in the expression of cell cycle regulators such as p21 and cyclin D1.

• Biomolecules & Therapeutics
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• v.19 no.2
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• pp.187-194
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• 2011

Atherosclerosis and post-angiography restenosis are associated with intimal thickening and concomitant vascular smooth muscle cell (VSMC) proliferation. Obovatol, a major biphenolic component isolated from the Magnolia obovata leaf, is known to have anti-inflammatory and anti-tumor activities. The goal of the present study was to enhance the inhibitory effects of obovatol to improve its potential as a preventive or therapeutic agent in atherosclerosis and restenosis. Platelet-derived growth factor (PDGF)-BB-induced proliferation of rat aortic smooth muscle cells (RASMCs) was examined in the presence or absence of a newly synthesized obovatol derivative, OD78. The observed anti-proliferative effect of OD78 was further investigated by cell counting and [$^3H$]-thymidine incorporation assays. Treatment with 1-4 ${\mu}M$ OD78 dose-dependently inhibited the proliferation and DNA synthesis of 25 ng/ml PDGF-BB-stimulated RASMCs. Accordingly, OD78 blocked PDGF-BB-induced progression from the $G_0/G_1$ to S phase of the cell cycle in synchronized cells. OD78 decreased the expression levels of CDK4, cyclin E, and cyclin D1 proteins, as well as the phosphorylation of retinoblastoma protein and proliferating cell nuclear antigen; however, it did not change the CDK2 expression level. In addition, OD78 inhibited downregulation of the cyclin-dependent kinase inhibitor (CKI) $p27^{kip1}$. However, OD78 did not affect the CKI $p21^{cip1}$ or phosphorylation of early PDGF signaling pathway. These results suggest that OD78 may inhibit PDGF-BB-induced RASMC proliferation by perturbing cell cycle progression, potentially through $p27^{kip1}$ pathway activation. Consequently, OD78 may be developed as a potential anti-proliferative agent for the treatment of atherosclerosis and angioplasty restenosis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.7
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• pp.907-913
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• 2012

Piceatannol (trans-3,4,3',5'-tetrahydroxystilbene) is a polyphenol detected in grapes, rhubarb, and sugarcane. Although recent experimental data revealed that this compound is known to exhibit immunosuppressive and antitumorigenic activities in several cell lines, the molecular mechanisms underlying anticancer activity are poorly understood. In the present study, we investigated possible further mechanisms by which piceatannol exerts its anti-proliferative action in cultured human gastric cancer AGS cells. Piceatannol treatment resulted in the inhibition of growth and G1 arrest of the cell cycle in a concentration-dependent manner, as determined by MTT assay and flow cytometry analysis. The induction of G1 arrest by piceatannol was associated with the modulation of cyclin-dependent kinases (Cdks) and cyclins, up-regulation of the expression of Cdk inhibitor p21 (WAF1/CIP1) in both transcriptional and translational levels, and the inhibition of phosphorylation of retinoblastoma proteins and E2F1 expression. In addition, piceatannol treatment caused a progressive decrease in the expression levels of cyclooxygenase (COX)-2 without significant changes in the levels of COX-1, which was correlated with a decrease in prostaglandin $E_2$ synthesis.

• Journal of Life Science
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• v.29 no.1
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• pp.105-111
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• 2019

In recent years, progress has been made in the search for the development of new anti-cancer agents by employing specific inhibitors of histone deacetylase (HDAC)-6 to block signal transduction pathways in cancer cells. This study examined the effects of tubastatin A (TubA), an HDAC-6 inhibitor, on the growth and development of immature oocytes in murine ovaries using RNA sequencing analysis. The results from a gene set enrichment analysis (GSEA) indicated that the expression of most of the gene sets involved in the cell cycle and control and progression of meiosis decreased in the TubA-treated group as compared with that in germinal vesicle (GV) stage oocytes. In addition, an ingenuity pathway analysis (IPA) suggested that TubA not only caused increased expression of p53 and pRB and decreased expression of CDK4/6 and cyclin D but also caused elevated expression of genes involved in the control of the DNA check point in G2/M stage oocytes. These results suggest that TubA may induce cell cycle arrest and apoptosis through the induction of changes in the expression of genes involved in signal transduction pathways associated with DNA damage and the cell cycle of immature oocytes in the ovary.

• Journal of Life Science
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• v.22 no.12
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• pp.1688-1696
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• 2012

Oenanthe javanica has been used as a food source and also in traditional folk medicine for its detoxifying properties and anti-microbial effects since ancient times. In this study, we evaluated the effect and mechanism of O. javanica seed methanol extract (OJSE) on adipocyte differentiation by 3T3-L1 preadipocytes. Under non-toxic conditions, OJSE treatment resulted in a dose-dependent inhibition of lipid droplet generation and triglyceride accumulation by suppressing adipocyte differentiation, which are associated with the decreased expression of key proadipogenic transcription factors including CCAAR/enhancer binding protein ${\alpha}$, ${\beta}$ ($C/EBP{\alpha}$, $C/EBP{\beta}$) and peroxisome proliferator-activated receptor ${\gamma}$ ($PPAR{\gamma}$). OJSE also significantly inhibited proliferation and differentiation of 3T3-L1 preadipocytes through G1-phase arrest, indicating that OJSE blocked mitotic clonal expansion during adipocyte differentiation. Investigation of the alteration of G1 phase arrest-related proteins indicated a dose-dependent increase in the expression of p21 and reduction in expression of cyclin E, Cdk2, E2F-1 and phospho-Rb by OSJE. Taken together, these results suggest that OJSE inhibits adipocyte differentiation by blocking the mitotic clonal expansion, which is accompanied by preadipocyte cell cycle arrest.

• Journal of Yeungnam Medical Science
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• v.22 no.2
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• pp.166-182
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• 2005

Background: Cyclin-dependent kinase (CDK) inhibitors are family of molecules that regulate the cell cycle. The CDKN2, a CDK4 inhibitor, also called p16, has been implicated in human tumorigenesis. The CDKN2 inhibits the cyclin/CDK complexes which regulate the transition from G1 to S phase of cell cycle. There is a previous report that homozygous deletion of CDKN2 region on chromosome 9p21 was detected frequently in astrocytoma, glioma and osteosarcoma, less frequently in lung cancer, leukemia and ovarian cancer, but not detected in colon cancer and neuroblastoma. However, little is known about the relationship between CDKN2 and laryngeal cancer. Therefore this study was initiated to investigate the role of CDKN2 in human laryngeal squamous cell carcinoma development.1) Materials and methods: We used 5 human laryngeal carcinoma cell lines whether they have deletions or losses of CDKN2 gene expression by DNA-PCR or RT-PCR, respectively. We examined 8 fresh frozen human laryngeal cancer tissues to detect the loss of heterozygosity (LOH) of CDKN2. PCR was performed by using microsatellite markers of short arm of human chromosome 9 (D9S126, D9S144, D9S156, D9S161, D9S162, D9S166, D9S171, D9S200 and D9SIFNA). For informative cases, allelic loss was scored if the signal of one allele was significantly decreased in tumor DNA when compared to the same allele in normal DNA. Results: The CDKN2 DNA deletion was observed in 3 cell lines. The CDKN2 mRNA expression was observed in only one cell line, which was very weak. LOH was detected in 7 cases (87.5%). Conclusion: These results suggest that CDKN2 plays a role in the carcinogenesis of human laryngeal squamous cell carcinoma.

• 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 Life Science
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• v.23 no.6
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• pp.832-837
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• 2013

In this study, it was investigated the possible mechanisms by which glutamine deprivation exerts its anti-proliferative action in cultured human prostate carcinoma PC3 cells. Glutamine deprivation resulted in inhibition of growth and G2/M arrest of the cell cycle in a time-dependent manner without apoptosis induction, as determined by MTT assay, DAPI staining and flow cytometry analyses. The induction of G2/M arrest by glutamine deprivation was associated with the inhibition of expression of Cdc2, cyclin A and cyclin B1, and up-regulation of the expression of cyclin-dependent kinase (Cdk) inhibitor p21(WAF1/CIP1) in both transcriptional and translational levels. Moreover, glutamine deprivation increased the phosphorylation of checkpoint kinase (Chk)1 and Chk2; however, the levels of Cdc25C phosphorylation were decreased in response to glutamine deprivation in a time-dependent manner. Our data provide a first biochemical evidence that glutamine deprivation suppresses cell viability through G2/M phase arrest without induction of apoptosis in PC3 cells.

• The Korea Journal of Herbology
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• v.22 no.2
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• pp.35-43
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• 2007

Objectives : The purpose of this study was to investigate the effect of Bo-du-san (BOS) on apoptosis in human gastric cancer cells, SNU-l cells. BOS, a drug preparation consisting of two herbs, that is, Crotonis Fructus (Strychni ignatii Semen, bodu in Korean) and Glycyrrhizae Radix (Glycyrrhizae uralensis FISCH, Gamcho in Korean). Methodss : In this study, methanol extract of BOS was examined for cytotoxic activity on human gastric cancer cells, SNU-1 cells, using XTT assay, with an IC50 value was 0.7 mg/ml and 0.3 mg/ml at 24 hrs and 48 hrs, respectively. Apoptosis induction by BDS in SNU-l cells was verified by the induction of DNA fragmentation, cleavage of poly ADP-ribose polymerase (PARP), and activation of caspase-3, -8 and -9. Inhibitors of caspase-3, -8 and -9 (Ac-DEVD-CHO, Z-IETD-FMK and Z-LEHD-FMK) efficiently blocked BOS-induced cell death of SNU-l. Resultss : BOS-induced cell death was via caspase dependent apoptosis. Moreover, treatment of BOS result in the decrease the G1/S cycle regulation proteins (cyclin D1 and E) expression and increase CDK inhibitor proteins (p21 and p27) expression, and increase apoptotic protein, p53 expression. Thus, BOS induces apoptosis in SNU-1 cells via cell cycle arrested in G1 phase. Conclusions : These results indicated that BOS has some potential for use as an anti-cancer agent.