• Radiation Oncology Journal
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• v.21 no.4
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• pp.306-314
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• 2003

Purpose : In our Previous study, we have shown the main cel1 death pattern Induced by irradiation or protein tyrosine kinase (PTK) inhibitors in K562 human myeiogenous leukemic cell line. Death of the cells treated with irradiation alone was characterized by mitotic catastrophe and typical radiation-induced apoptosis was accelerated by herblmycin A (HMA). Both types of cell death were inhibited by genistein. In this study, we investigated the effects of HMA and genistein on cell cycle regulation and its correlation with the alterations of radiation-induced cell death. Materials and Methods: K562 cells In exponential growth phase were used for this study. The cells were Irradiated with 10 Gy using 6 MeV Linac (200-300 cGy/min). Immediately after irradiation, cells were treated with 250 nM of HMA or 25 $\mu$N of genistein. The distributions of cell cycle, the expressions of cell cycle-related protein, the activities of cyclin-dependent kinase, and the yield of senescence and differentiation were analyzed. Results: X-irradiated cells were arrested In the G2 phase of the cell cycle but unlike the p53-positive cells, they were not able to sustain the cell cycle arrest. An accumulation of cells in G2 phase of first ceil-cycle post-treatment and an increase of cyclin Bl were correlated with spontaneous, premature, chromosome condensation and mitotic catastrophe. HMA induced rapid G2 checkpoint abrogation and concomitant p53-independent Gl accumulation. HMA-induced cell cycle modifications correlated with the increase of CDK2 kinase activity, the decrease of the expressions of cyclins I and A and of CDK2 kinase activity, and the enhancement of radiation-induced apoptosis. Genistein maintained cells that were arrested in the G2-phase, decreased the expressions of cyclin Bl and cdc25c and cdc25C kinase activity, increased the expression of pl6, and sustained senescence and megakaryocytic differentiation. Conclusion: The effects of HMA and genistein on the radiation-induced cell death of KS62 cells were closely related to the cell cycle regulatory activities. In this study, we present a unique and reproducible model in which for investigating the mechanisms of various, radiation-induced, cancer cell death patterns. Further evaluation by using this model will provide a potent target for a new strategy of radiotherapy.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5753-5757
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• 2012

Apoptosis, also known as cell suicide or programmed cell death, removes unwanted and genetically damaged cells from the body. Evasion of apoptosis is one of the major characteristic features of rapidly proliferating tumor cells. Chemopreventive agents inhibit or suppress tumor formation through apoptotic induction in target tissues. The aim of the present study was to investigate the pro-apoptotic potential of lupeol during 7,12-dimethylbenz(a) anthracene (DMBA) induced hamster buccal pouch carcinogenesis. Topical application of 0.5% DMBA three times a week for 14 weeks in the buccal pouches of golden Syrian hamsters resulted in oral squamous cell carcinoma. The expression pattern of apoptotic markers was analyzed using immunohistochemistry (p53, Bcl-2, Bax) and ELISA reader (caspase 3 and 9). In the present study, 100% tumor formation with defects in apoptotic markerexpression pattern was noticed in hamsters treated with DMBA alone. Oral administration of lupeol at a dose of 50mg/kg bw completely prevented the formation oral tumors as well as decreased the expression p53 and Bcl-2, while increasing the expression of Bax and the activities of caspase 3 and 9. The present study thus indicated that lupeol might inhibit DMBA-induced oral tumor formation through its pro-apoptotic potential in golden Syrian hamsters.

• Development and Reproduction
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• v.1 no.1
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• pp.79-89
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• 1997

Recent studies have demonstrated that apoptotic cell death plays an important role in the mechanism underlying follicular atresia and luteolysis. However, the mechanisms responsible for initiating these processes have not been elucidated. In in vitro fertilization (IVF) programs, it is highly possible that continuous and repeated administration of FSH/hMG and GnRH agonists for the usage of ovarian hyperstimulation may induce apoptotic death of granulosa cells leading to atresia in the human ovarian follicles. The present study was performed to investigate whether FSH/hMG and GnRh agonists used for a longer period in controlled ovarian hyperstimulation has any effect on the apoptosis of granulosa-luteal (GL) cells obtained from hyperstimulated ovaries. To examine apoptotic cell death in the GL cells, cells were stained with acridie orange followed by observed in some of GL cells. Similar but distinct staining of apoptotic GL cells was observed when the cells were examined by using in situ TUNEL method. The healthy-looking cells with normal nuclear morphology were not stained, whereas cells with pyknotic nuclei or with apoptotic nuclei were intensively stained. After examining the ultrastructural features of GL cells by TEM, it was confirmed that the majority of cells seemed to have normal nuclei while GL cells undergoing apoptotic cel death were rarely found. The DNA extracted from GL cells showed a typical pattern of fragmentation following DNA electrophoretic analysis. We have confirmed that the apoptosis occurs in granulosa-luteal cells obtained from hyperstimulated ovaries. Technically, in situ apoptosis detection method is simple and reproducible and is well suited to identify the quality of oocytes retrieved from hyperstimulated ovaries.

• The Journal of Korean Medicine
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• v.25 no.2
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• pp.138-150
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• 2004

Objectives : Alzheimer's disease (AD) is a geriatric dementia that is widespread in old age. In the near future AD will be the biggest problem in public health service. Although a variety of oriental prescriptions, including Sesim-tang, have been traditionally utilized for the treatment of AD, their pharmacological effects and action mechanisms have not yet been fully elucidated. The present study investigated the effects of Sesim-tang on apoptotic cell death induced by CT105 (carboxy terminal 105 amino acid peptide fragment of APP) overexpression in SK-N-SH neuroblastoma cell lines. Methods: We studied the regenerative and inhibitory effects on Alzheimer's disease in CT105-induced SK-N-SH cell lines by Sesim-tang water extract. We examined for cell morphological pattern, DNA fragmentation, LDH activity assay, zymography assay, and immunohistochemistric analysis. Additionally, we investigated the association between the CT105 and neurite degeneration caused by CT105-induced apoptotic response in neurone cells. Results: Findings from our experiments have shown that Sesim-tang inhibits the synthesis or activities of CT105, which has neurotoxicities and apoptotic activities in the cell line. In addition, pretreatment with Sesim-tang ($>50\mu\textrm{g}/ml$ for 12 hours) partially prevented CT105-induced cytotoxicity in SK-N-SH cell lines. SK-N-SH cell lines overexpressed with CT105 exhibited remarkable apoptotic cell damage. Based on morphological observations by phase-contrast microscope and LDH activity measurements in the culture media, the CT105-induced cell death was significantly inhibited by Sesim-tang water extract. Sesim-tang was found to reduce the expression of APP and caspase-3 induced by CT105 in SK-N-SH cell lines and in rat hippocampus. Conclusions: As the result of this study, in the Sesim-tang group, apoptosis in the nervous system is inhibited, the repair against the degeneration of SK-N-SH cell lines by CT105 expression is promoted. Hence, Sesim-tang may be beneficial for the treatment of AD.

• The Korean Journal of Food And Nutrition
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• v.25 no.4
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• pp.863-870
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• 2012

Though hydrogen peroxide ($H_2O_2$) causes a deleterious effect to cells with its reactive oxygen species resulting in cell death, S-allyl cysteine (SAC, a bioactive organosulfur compound of aged garlic extract) has been known to have a cytoprotective effect. Few reported profiles of gene expression of $H_2O_2$ and SAC treated human cord blood derived mesenchymal stem cells (MSC). This study revealed changes in the profile of twenty-one genes grouped by oxidative stress, antioxidant, cell death, anti-apoptosis and anti-aging by quantitative real time PCR. A concentration of $100{\mu}M$ of SAC or $50{\mu}M$ of $H_2O_2$ was applied to MSC which show moderate growth and apoptosis pattern. $H_2O_2$ treatment enhanced expression of eleven genes out of twenty-one genes compared with that of control group, on the contrary SAC suppressed expression of eighteen genes out of twenty-one genes except C ros oncogene. SAC decreased expression of oxidative stress genes such as SOD1, CAT and GPX. These results seemed consistent with reports which elucidated over-expression of NF-${\kappa}$B by $H_2O_2$, and suppression of it by SAC. This study will confer basic information for further experiments regarding the effects of SAC on gene levels.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.6
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• pp.565-570
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• 1999

Intracellular accumulation of bile acids in the hepatocytes during cholestasis is thought to be pathogenic in cholestatic liver injury. Due to the detergent-like effect of the hydrophobic bile acids, hepatocellular injury has been attributed to direct membrane damage. However histological findings of cholestatic liver diseases suggest apoptosis can be a mechanism of cell death during cholestatic liver diseases instead of necrosis. To determine the pattern of hepatocellular toxicity induced by bile acid, we incubated primary cultured rat hepatocytes with a hydrophobic bile acid, Glycochenodeoxycholate (GCDC), up to 5 hours. After 5 hours incubation with $400\;{\mu}M$ GCDC, lactate dehydrogenase released significantly. Cell viability, quantitated in propidium iodide stained cells concomitant with fluoresceindiacetate was decreased time- and dose-dependently. Most nuclei with condensed chromatin and shrunk cytoplasm were heavily labelled time- and dose-dependently by a positive TUNEL reaction. These findings suggest that both apoptosis and necrosis are involved in hepatocytes injury caused by GCDC.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.643-654
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• 2021

Phytophthora capsici is one of the most destructive hemibiotrophic pathogens; it can cause blight in chili peppers, and secrete various effector proteins to infect the plants. These effectors contain an N-terminal conserved RXLR motif. Here, we generated full-length RXLR effector coding genes using primer pairs, and cloned them into the pGR106 vector for in planta expression. Two of these genes, PcREK6 and PcREK41 (P. capsici RXLR effector from the Korea isolate), were further characterized. PcREK6 and PcREK41 genes showed that they encode effector proteins with a general modular structure, including the N-terminal conserved RXLR-DEER motif and signal peptide sequences. PcREK6 and PcREK41 expressions were strongly induced when the chili pepper plants (Capsicum annuum) were challenged with P. capsici. These results provide molecular evidence to elucidate the virulence or avirulence factors in chili pepper. Our results also showed that two effectors induce hypersensitive response (HR) cell death when expressed in chili leaves. Cell death suppression assays in Nicotiana benthamiana revealed that most effectors could not suppress programmed cell death (PCD) triggered by Bcl-associated X (BAX) or Phytophthora infestans elicitin (INF1). However, PcREK6 fully suppressed PCD triggered by BAX, while PcREK41 partially suppressed PCD triggered by INF1 elicitin. These results suggest that PcREK effectors from P. capsici interact with putative resistance (R) proteins in planta, and different effectors may target different pathways in a plant cell to suppress pattern-triggered immunity (PTI) or effector-triggered immunity (ETI).

• BMB Reports
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• v.38 no.4
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• pp.391-398
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• 2005

3-hydrogenwadaphnin (3-HK) is a new daphnane-type diterpene ester isolated from Dendrostellera lessertii with strong anti-tumoral activity in animal models and in cultures. Here, prolonged effects of this new agent on proliferation and viability of several different cancerous cell lines were evaluated. Using [$^3H$]thymidine incorporation, it was found that the drug inhibited cell proliferation and induced G1/S cell cycle arrest in leukemic cells 24 h after a single dose treatment. The cell viability of Jurkat cells was also decreased by almost 10%, 31% and 40% after a single dose treatment (7.5 nM) at 24, 48 and 72 h, respectively. The drug-treated cells were stained with acridine orange/ethidium bromide to document the chromatin condensation and DNA fragmentation. These observations were further confirmed by detection of DNA laddering pattern in the agarose gel electrophoresis of the extracted DNA from the treated cells. Treatment of K562 cells with the drug at 7.5, 15 and 30 nM caused apoptosis in 25%, 45% and 65% of the cells, respectively. Exogenous addition of $25-50\;{\mu}M$ guanosine and/or deoxyguanosine to the cell culture of the drug-treated cells restored DNA synthesis, released cell arrest at G1/S checkpoint and decreased the apoptotic cell death caused by the drug. These observations were not made using adenosine. However, the drug effects on K562 cells were potentiated by hypoxanthine. Based on these observations, perturbation of GTP metabolism is considered as one of the main reasons for apoptotic cell death by 3-HK.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.749-755
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• 2001

High Electromagnetic Field (EMF) with an intensity of 1 mT (Tesla) inhibited the growth of both human normal lung and immune T cell down to $20-30\%$, compared to that of an unexposed case. The human T-cells, Jurkat, were more severely affected by EMF than the human lung cells, which showed a relatively slow cell growth and substantial releas of $Ca^+2$ (3.5 times higher than the human T-cells). However, the growth of hepatoma carcinoma, Hep3B, was enhanced by twice that of an unexposed case. The EMF intensity and exposure time did not affect the growth of the cancer cells very much, while it significantly affected the growth of normal cells. Accordingly, it is possible that EMFs may play a role in the initiation of cancer. The EMFs disturbed the signal transduction and membrane systems, such that a five times higher amount of PKC-${\alpha}$ was released from the cell membrane than in the control. Extended exposure to EMFs, for more than 48 hours, also led to 1 $90\%$ necrotic death pattern from apoptotic cell death. Finally, EMF at an intensity of 1mT with a 24-T exposure promoted the differentiation of HL-60 cells to monocytes/macrophages, possibly causing potential acute leukemia.

• BMB Reports
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• v.40 no.2
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• pp.277-285
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• 2007

PCD (programmed cell death) is important mechanism for development, homeostasis and disease. To analyze the gene expression pattern in brain cells undergoing PCD in response to serum deprivation, we analyzed the cDNA microarray consisting of 2,300 genes and 7 housekeeping genes of cortical cells derived from mouse embryonic brain. Cortical cells were induced apoptosis by serum deprivation for 8 hours. We identified 69 up-regulated genes and 21 down-regulated genes in apoptotic cells. Based on the cDNA microarray data four genes were selected and analyzed by RT-PCR and northern blotting. To characterize the role of UNC-51-like kinase (ULK2) gene in PCD, we investigated cell death effect by ULK2. And we examined expression of several genes that related with PCD. Especially GAPDH was increased by ULK2. Theses findings indicated that ULK2 is involved in apoptosis through p53 pathway.