• Journal of Life Science
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• v.19 no.1
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• pp.1-8
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• 2009

In this paper, to elucidate the further mechanisms of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced growth arrest, we investigated the effect of MNNG on cell cycle and proliferation in U937 cells, a p53-null human myeloid leukemia cell line. It was found that MNNG causes an arrest at the G2/M phase of the cell cycle and induces apoptosis, which is closely correlated to inhibition of cyclin B1 and cyelin-dependent kinase (Cdk) 2-associated kinase activities. MNNG treatment in. creased protein and mRNA levels of the Cdk inhibitor p21(WAF1/CIP1), and activated the reporter construct of a p21 promoter. By using p21 promoter deletion constructs, the MNNG-responsive element was mapped to a region between 113 and 61 relative to the transcription start site. These data indicate that in U937 cells MNNG can circumvent the loss of wild-type p53 function and induce critical downstream regulatory events leading to transcriptional activation of p21. Present results indicate that the p53-independent up-regulation of p21 by MNNG is likely responsible for the inhibition of cyclin/Cdk complex kinase activity rather than the down-regulation of cyclins and Cdks expression. These novel phenomena have not been previously described and provide important new insights into the possible biological effects of MNNG.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.91.2-91.2
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• 2003

Cyclin-dependent kinases (CDKs) regulate the cell division cycle, apoptosis, transcription and differentiation. Inhibition of CDK is a promising target in development of anti-cancer agents. An indirubin analog (AGM01l), a CDK inhibitor, is a synthetic compound that inhibits human cancer cell growth in vitro. AGM01l showed a potent cytotoxicity in cultured human cancer cell lines (IC$\sub$50/ = 5.43 ${\mu}$M for A549, human colon cancer cell; IC$\sub$50/ = 1.21 ${\mu}$M for SNU-638, human stomach cancer cell; IC$\sub$50/ 9.23 ${\mu}$M for HL-60, human leukemia cell). (omitted)

• BMB Reports
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• v.44 no.8
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• pp.553-557
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• 2011

We previously reported that CDK2/Cyclin A can phosphorylate and activate the transcription factor NF-Y. In this study, we investigated a potential regulatory role for NF-Y in the transcription of Cyclin A and other cell cycle regulatory genes. Gel-shift assays demonstrate that NF-Y binds to CCAAT sequences in the Cyclin A promoter, as well as to those in the promoters of cell cycle G2 regulators such as CDC2, Cyclin B and CDC25C. Furthermore, expression of Cyclin A increases NF-Y's affinity for CCAAT sequences in the CDC2 promoter; however, Cyclin A's induction of CDC2 transcription is antagonized by p21, an inhibitor of CDK2/Cyclin A. These results suggest a model wherein NF-Y binds to and activates transcription from the Cyclin A promoter, increasing cellular levels of Cyclin A/CDK2 and potentiating NF-Y's capacity for transcriptional transactivation, and imply a positive feedback loop between NF-Y and Cyclin A/CDK2. Our findings are additionally indicative of a role for Cyclin A in activating Cyclin B/CDK1 through promoting NF-Y dependent transcription of Cyclin B and CDC2; NF-Y mediated crosstalk may therefore help to orchestrate cell-cycle progression.

• Journal of Life Science
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• v.14 no.5
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• pp.800-808
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• 2004

Resveratrol, a phytoalexin found at high levels in grapes and in grape products such as red wine, has been reported to possess a wide range of biological and pharmacological activities including antioxident, anti-inflammatory, anti-mutagenic, and anti-carcinogenic effects. According to recent studies, this compound is an effective inhibitor of cell growth in general, triggers partial arrest of the cell cycle and induce apoptosis. In this study, the anti-proliferative effects of resveratrol in A549 human lung carcinoma cells were investigated. It is shown that resveratrol induced the growth inhibition in a time-dependent manner and morphological changes of A549 cells, which were associated with induction of S phase arrest of the cell cycle and apoptotic cell death. The Bcl-$X_L$levels were markedly down-regulated in resveratrol treated cells, however, Bax and Bcl-2 were remained unchanged. Resveratrol treatment induced the proteolytic degradation of Sp-l and proliferating cell nuclear antigen protein, and inhibited the expression of $\beta$-catenin protein. Resveratrol treatment also induced a marked up-regulation of cyclin-dependent kinase (Cdk) inhibitor p21 and inhibited the kinase activities of Cdk2 and Cdk4. In addition, resveratrol treatment inhibited the levels of cyclooxygenase (COX)-2 mRNA and protein, and the release of prostagladin E2 without alteration of COX-1 expression. Taken together, these findings suggest that resveratrol may be a potential chemotherapeutic agent for the control of human lung carcinorma cells.

• Environmental Analysis Health and Toxicology
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• v.27
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• pp.10.1-10.7
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• 2012

Objectives: In recent years, a number of structurally diverse Histone deacetylase (HDAC) inhibitors have been identified and these HDAC inhibitors induce growth arrest, differentiation and/or apoptosis of cancer cells in vitro and in vivo. This study aimed at investigating the antitumor activity of newly synthesized HDAC inhibitor, 3-(4-dimethylamino phenyl)-N-hydroxy-2-propenamide (IN-2001) using human breast cancer cells. Methods: We have synthesized a new HDAC inhibitor, IN-2001, and cell proliferation inhibition assay with this chemical in estrogen receptor-positive human breast cancer MCF-7 cells. Cell cycle analysis on MCF-7 cells treated with IN-2001 was carried out by flow cytometry and gene expression was measured by RT-PCR. Results: In MCF-7 cells IN-2001 showed remarkable anti-proliferative effects in a dose- and time-dependent manner. In MCF-7 cells, IN-2001 showed a more potent growth inhibitory effect than that of suberoylanilide hydroxamic acid. These growth inhibitory effects were related to the cell cycle arrest and induction of apoptosis. IN-2001 showed accumulation of cells at $G_2$/M phase and of the sub-$G_1$ population in a time-dependent manner, representing apoptotic cells. IN-2001-mediated cell cycle arrest was associated with HDAC inhibitor-mediated induction of CDK inhibitor expression. In MCF-7 cells, IN-2001 significantly increased $p21^{WAF1}$ expression. Conclusions: In summary, cyclin-dependent kinase (CDK) induced growth inhibition, possibly through modulation of cell cycle and apoptosis regulatory proteins, such as CDK inhibitors, and cyclins. Taken together, these results provide an insight into the utility of HDAC inhibitors as a novel chemotherapeutic regime for hormone-sensitive and insensitive breast cancer.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.151-152
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• 2001

MCS-5A, novel Cdk inhibitor, has been reported that it has exerted cell cycle arrest action and apoptotic effect to the human promyelocytic leukemias cell. The purpose of this study is to verify these effects of MCS-5A on human promyelocytic leukemia (HL-60) cells and to clarify the action of mechanism on MCS-5A-inducing apoptosis.(omitted)

• BMB Reports
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• v.44 no.8
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• pp.529-534
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• 2011

Ribosomal protein S3 (rpS3) is a multifunctional protein involved in translation, DNA repair, and apoptosis. The relationship between rpS3 and cyclin-dependent kinases (Cdks) involved in cell cycle regulation is not yet known. Here, we show that rpS3 is phosphorylated by Cdk1 in G2/M phase. Co-immunoprecipitation and GST pull-down assays revealed that Cdk1 interacted with rpS3. An in vitro kinase assay showed that Cdk1 phosphorylated rpS3 protein. Phosphorylation of rpS3 increased in nocodazole-arrested mitotic cells; however, treatment with Cdk1 inhibitor or Cdk1 siRNA significantly attenuated this phosphorylation event. The phosphorylation of a mutant form of rpS3, T221A, was significantly reduced compared with wild-type rpS3. Decreased phosphorylation and nuclear accumulation of T221A was much more pronounced in G2/M phase. These results suggest that the phosphorylation of rpS3 by Cdk1 occurs at Thr221 during G2/M phase and, moreover, that this event is important for nuclear accumulation of rpS3.

• Journal of Life Science
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• v.16 no.5
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• pp.828-833
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• 2006

Maize (Zea mays L.) pistil cell death and stamen cell arrest are pivotal process on the sex determination, which diverges from bisexual state of floral meristem to unisexual state in staminate or pistillate floret. We investigated the temporal and spatial distribution of cell cycle gene expression during maize sex determination. The positive regulatory genes of cell cycle, cyclin A, cyclin B, cyclin dependent kinase (CDK) and Mad2 were highly expressed in the developing pistil and stamen but the expression was disappeared in the dying pistil and arresting stamens. In contrast, the negative regulatory genes of cell cycle, Wee1 and CDK inhibitor (CKI) were expressed in the arresting stamens in the wild-type ear and tasselseed2 mutant tassel, however, these genes were not detected in dying pistil although the cyclin B gene expression was disappeared. These results suggest that both the pistil cell death and stamen cell arrest process in maize sex determination are involved in cell cycle regulation, but the different expression patterns of negative regulatory cell cycle genes in the arresting stamens and aborting pistils suggest that the two processes may have distinctive modes of action.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.1
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• pp.213-219
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• 2003

We investigated the effects of Insamsapye-tang (ISSPT) water extract on the cell proliferation of human lung carcinoma A549 cells. ISSPT treatment resulted in the inhibition of cell proliferation in a concentration-dependent manner. This anti-proliferative effect of A549 cells by ISSSPT treatment was associated with morphological changes such as membrane shrinking and cell rounding up. DNA flow cytometric histograms showed that population of G1 phase of the cell cycle was increased by ISSPT treatment in a concentration-dependent manner. ISSPT treatment induced the levels of tumor suppressor p53 protein and cyclin-dependent kinase (Cdk) inhibitor p27 without significant alteration of cyclins and Cdks expression. In addition, ISSPT treatment resulted in down-regulation of phosphorylated retinoblastoma protein (pRB). However, the levels of p130, the pRB family protein, and transcription factors. E2F-1 and E2F-4. were remained unchanged. The present results indicated that ISSPT-induced inhibition of lung cancer cell proliferation is associated with the blockage of G1/S progression and the induction of apoptosis, and we suggest that ISSPT will be an effective therapeutic agent on human lung cancer.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.1
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• pp.167-173
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• 2005

To investigate the possible molecular mechanism (s) of bee venom as a candidate of anti-cancer drug, we examined the effects of the compound on the growth of human lung carcinoma cell line A549. Bee venom treatment declined the cell growth and viability of A549 cells in a concentration-dependent manner, which was associated with induction of apoptotic cell death. Bee venom down-regulated the levels of anti-apoptotic genes such as Bcl-2 and Bcl-XS/L, however, the levels of Bax, a pro-apoptotic gene, were up-regulated. Bee venom treatment induced not only tumor suppressor p53 but also cyclin-dependent kinase inhibitor p21WAF1/CIP1 expression in a dose-dependent manner. Furthermore, bee venom treatment induced the down-regulation of telomerase reverse transcriptase mRNA and telomeric repeat binding factor expression of A549 cells, however, the levels of telomerase-associated protein-1 and c-myc were not affected. Taken together, these findings suggest that bee venom-induced inhibition of human lung cancer cell growth is associated with the induction of apoptotic cell death via regulation of several major growth regulatory gene products, and bee venom may have therapeutic potential in human lung cancer.